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Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table. Actinium forms a trivalent cation in water. Actinium salts are generally soluble, although there is not a lot of information available due to its radioactive nature.
A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation. As with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. Actinium is found only in traces in uranium and thorium ores as the isotope 227Ac, which decays with a half-life of 21.772 years, predominantly emitting beta and sometimes alpha particles, and 228Ac, which is beta active with a half-life of 6.15 hours.
Alkalinity is defined as any compound with the ability to neutralize acidity. Although we generally think of alkalinity as being the carbon dioxide, bicarbonate, carbonate species, it also includes ammonia borate and even sulfate.
Aluminium or aluminum (in North American English) is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal. Aluminium is the third most abundant element in the Earth’s crust (after oxygen and silicon) and its most abundant metal.
Aluminium makes up about 8% of the crust by mass, though it is less common in the mantle below. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals. The chief ore of aluminium is bauxite.
Despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of their abundance, the potential for a biological role is of continuing interest and studies continue.Aluminium is remarkable for its low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium is most famously used in aluminum foil and aluminum baking dishes. However, its alloys are vital to the aerospace industry and important in transportation and structures, such as building facades and window frames. Aluminum is a relatively good electrical conductor. The oxides and sulfates are the most useful compounds of aluminium. Aluminum salts such as alum (aluminum sulfate) are widely used as coagulants in the treatment of potable water.
Phosphoric acid is not completely ionized allowing for a few ion exchange reactions to be used. Modest amounts of aluminum can be removed from relatively concentrated solutions and effectively removed using sulfuric acid.
Aluminum in drinking water is often present as a suspended solid rather than as an ion.
Aluminate is a common source of aluminum used as a coagulant in water treatment.
Americium is a man-made element in the actinide series but has properties more similar to the lanthanides than other actinides. It is transmuted from plutonium and uranium in commercial nuclear reactors. Americium 241 is used in smoke detectors and has much longer half life (432 years). Although the +3 valence is most common, Americium also forms +2 and +4 valence depending on matrix effects and redox potential.
At higher concentrations amines are molecular liquids and can be effectively deionized by a combination of hydrogen form cation resins such as CG8-H and CG10-H followed by hydroxide form anion resins (such as SBG1-OH or SBG2-OH). If the amines are anhydrous (without water) they pull water out of the resin. This complicates regenerations because the rewetting process must be done slowly to avoid bead breakage.
Behavior of amines is similar to that of ammonia. At low concentrations amines are ionized as monovalent cations and are removed by hydrogen form cation exchange resins such as CG8-H and CG10-H. Due to the high flow rates and the nature of amines not being fully ionized, the working zone of an ion exchange bed is rather deep and full utilization of the resins capacity is not always obtained.
Behavior of amines is similar to that of ammonia. At low concentrations amines are ionized as monovalent cations and are removed by cation exchange resins such as CG8 and CG10.
Ammonia gas diffuses into the resin beads and then exchanges as ammonium ion. Hydrogen form cation resins have very high capacity for ammonia when regenerated with acid.
Ammonium ion forms when pH is less than 9 (preferably less than 8). Ammonium is a monovalent cation. Cation resins such as CG8 and CG10 have modest selectivity for ammonium ion compared to sodium but poor selectivity compared to hardness ions such as calcium and magnesium. SIR-600 has very high selectivity for ammonium but fairly low capacity and requires a rather large salt dose (typically at least 30 lbs NaCl per cu ft).
Antimony is a chemical element with symbol Sb (from Latin: stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name, kohl. Metallic antimony was also known, but it was erroneously identified as lead upon its discovery. In the West, it was first isolated by Vannoccio Biringuccio and described in 1540.
For some time, China has been the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony are roasting and reduction with carbon or direct reduction of stibnite with iron.
Pure antimony is a soft brittle metal. Antimony forms similar compounds to its sister element arsenic and is most commonly found in its +3 oxidation state. The largest applications for metallic antimony is an alloy with lead and tin and the lead antimony plates in lead–acid batteries. Alloys of lead and tin with antimony have improved properties for solders, bullets and plain bearings.It is also used as a component in fire retardants and in certain organic chemical synthesis.
The iron based strong base anion hybrids are effective to remove antimony from borated waters found in nuclear power plants.
Argon is a chemical element with symbol Ar and atomic number 18. Argon is the third most abundant gas in the Earth’s atmosphere, more than twice as abundant as water vapor, 23 times as abundant as carbon dioxide, and more than 500 times as abundant as neon. Argon is also the most abundant noble gas in Earth’s crust.
Nearly all of the argon in Earth’s atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth’s crust. In the universe, argon-36 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas.
The name “argon” is derived from the Greek word ἀργόν, neuter singular form of ἀργός meaning “lazy” or “inactive”, as a reference to the fact that the element undergoes almost no chemical reactions.
It is used in welding and other applications that require an inert gas. Argon has limited solubility in water and can be removed by a variety of degasification techniques.
Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form is important to industry.
The primary use of metallic arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining, however
A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably many other species, including humans.
Arsenic is notoriously poisonous to multicellular life. Arsenic trioxide compounds are widely used as pesticides, herbicides and insecticides. As a result, arsenic contamination of groundwater supplies is a problem that affects millions of people around the world.
Arsenate is a divalent anion with affinity for anion resins similar to but slightly lower than that of sulfate Arsenate can be exchanged by strong base anion exchange resins and then adsorbed into the iron hybrid adsorbent of ASM-10-HP.
Except for Gallium arsenide (used as a semiconductor), other arsenide compounds are generally only of academic interest. Gallium arsenide is an important semiconductor because it has much lower electrical resistance than silicon and therefore lower power use and less heat generation.
In most cases arsenite should be oxidized to arsenate so that it is converted to a form more easily removed. Oxidation can be accomplished with chlorine or with oxygen catalyzed by various redox medias.
Astatine is a radioactive chemical element with the chemical symbol At and atomic number 85, and is the rarest naturally occurring element on the Earth’s crust. It occurs on Earth as the decay product of various heavier elements. All its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. Elemental astatine has never been viewed because any macroscopic sample would be immediately vaporized by its radioactive heating. It has yet to be determined if this obstacle could be overcome with sufficient cooling.
The bulk properties of astatine are not known with any certainty. Many of these have been estimated based on its periodic table position as a heavier analog of iodine, and a member of the halogens – the group of elements including fluorine, chlorine, bromine, and iodine. It is likely to have a dark or lustrous appearance and may be a semiconductor or possibly a metal; it probably has a higher melting point than that of iodine. Chemically, several anionic species of astatine are known and most of its compounds resemble those of iodine. It also shows some metallic behavior, including being able to form a stable monatomic cation in aqueous solution (unlike the lighter halogens). Astatine has metallic characteristics and can assume many different valances from -1, to +1, to +7 (all odd number valences). Astatine is a beta emitter and decays into Polonium 210.
Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Its hydroxide, known in pre-modern history as baryta, does not occur as a mineral, but can be prepared by heating barium carbonate.
The most common naturally occurring minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3), both insoluble in water. The barium name originates from the alchemical derivative “baryta”, from Greek βαρύς (barys), meaning “heavy.” Baric is the adjective form of barium. Barium was identified as a new element in 1774, but not reduced to a metal until 1808 with the advent of electrolysis.
Barium has few commercial uses. Barium salts are used in drilling mud due to high specific gravity of barium solutions, and as pure barium sulfate to enhance X-ray imaging. Barium is also used in making fireworks and occasionally as a getter for high vacuum applications.
Barium has high affinity for cation resins and can be readily removed along with other hardness ions such as calcium and magnesium. Care must be taken during regeneration to limit barium sulfate precipitation or leakage of suspended barium sulfate will occur. Regeneration of weak acid cation resin with hydrochloric acid followed by neutralization with caustic is one way to avoid the precipitation issues.
Berkelium is a transuranic radioactive chemical element with symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the University of California Radiation Laboratory where it was discovered in December 1949. This was the fifth transuranium element discovered after neptunium, plutonium, curium and americium.
The major isotope of berkelium, 249Bk, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the Oak Ridge National Laboratory in Tennessee, USA, and at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. The production of the second-most important isotope 247Bk involves the irradiation of the rare isotope 244Cm with high-energy alpha particles. It has a half life of 330 days and is an alpha emitter. The +3 valence is most likely although Berkelium also forms +2 and +4 valences.
Just over one gram of berkelium has been produced in the United States since 1967. There is no practical application of berkelium outside of scientific research which is mostly directed at the synthesis of heavier transuranic elements and transactinides.
Beryllium is a chemical element with symbol Be and atomic number 4. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars beryllium is depleted as it is fused and creates larger elements.
It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl. As a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal.
Beryllium improves many physical properties when added as an alloying element to aluminium, copper (notably the alloy beryllium copper), iron and nickel. Beryllium does not form oxides until it reaches very high temperatures. Tools made of beryllium copper alloys are strong and hard and do not create sparks when they strike a steel surface. In structural applications, the combination of high flexural rigidity, thermal stability, thermal conductivity and low density (1.85 times that of water) make beryllium metal a desirable aerospace material because it is light weight, high strength, and provides superior structural stability. These traits make it useful in aircraft components, missiles, spacecraft, and satellites.
Beryllium is transparent to ionizing radiation and is useful in certain types of reactor cores and for X-ray generators. Beryllium dust is quite corrosive and is considered toxic.
Bicarbonate alkalinity can be converted to carbon dioxide (gas dissolved in water) by exchanging cations present in the water for hydrogen ion. A variety of hydrogen cation resins can be used for the exchange. The conversion is typically followed by degasification to removed the carbon dioxide formed.
Bicarbonate alkalinity can be removed by various strong base anion resins in the hydroxide form (such as SBG1P-OH and SDBG2-OH), when coupled with hydrogen form cation resins (such as CG8-H or CG10-H). Bicarbonate can also be removed by deionizing mixed bed resins such as MBD-15 and MBD-10.
Bicarbonate alkalinity can be removed by a variety of strong base an ion resin and ionic forms including SBG2 and SBG1 in the chloride or in the hydroxide form.
Bismuth is a chemical element with the symbol Bi and the atomic number 83. Bismuth is a heavy metal that has similar properties to antimony and arsenic. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced but is often seen in air with a pink tinge owing to surface oxidation. Bismuth is the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals.
Bismuth metal has been known since ancient times, although it was often confused with lead and tin, which share some physical properties. The etymology is uncertain, but possibly comes from Arabic bi ismid, meaning having the properties of antimony or the German words weiße Masse or Wismuth (“white mass”), translated in the mid-sixteenth century to New Latin bisemutum.
It has low toxicity and is used in cosmetics, and in diarrhea medications. It is a semiconductor, which, when alloyed with antimony or selenium, is an efficient thermoelectric material for refrigeration or portable power generation. Bismuth is relatively insoluble in water but forms a trivalent cation in acidic solutions and a complex anion in very concentrated acids.
Bohrium is a chemical element with symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. It is a man made transuranic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, 270Bh, has a half-life of approximately 61 seconds.
In the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 7 elements as the fifth member of the 6d series of transition metals. Chemistry experiments have confirmed that bohrium behaves as the heavier homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements.
Its chemical properties are expected to be similar to manganese and technetium but since only a few atoms have ever been made its chemical properties have never been determined. Bohrium decays by alpha emission.
Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth’s crust.
Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known boron deposits are in Turkey, the largest producer of boron minerals.
Elemental boron is a metalloid that is found in small amounts in meteoroids but chemically uncombined boron is not otherwise found naturally on Earth. Industrially, very pure boron is produced with difficulty because of refractory contamination by carbon or other elements. Several allotropes of boron exist: amorphous boron is a brown powder; crystalline boron is silvery to black, extremely hard (about 9.5 on the Mohs scale), and a poor electrical conductor at room temperature. The primary use of elemental boron is as boron filaments with applications similar to carbon fibers in some high-strength materials. Almost all other uses are as boron compounds such as borosilicate glass and as an additive to fiberglass insulation. Boron is also used as a doping agent in semiconductor manufacturing and as a neutron moderator in light water reactors.
Boron (as borate) can be removed from brines of any concentration provided the pH is greater than 3. Flow rates must be kept low.
Bromine is a chemical element with symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. Its properties are thus intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek βρῶμος “stench”, referencing its sharp and disagreeable smell.
Elemental bromine is very reactive and thus does not occur free in nature, but in colourless soluble crystalline mineral halide salts, analogous to table salt. While it is rather rare in the Earth’s crust, the high solubility of the bromide ion (Br−) has caused its accumulation in the oceans. Commercially the element is easily extracted from brine pools, mostly in the United States, Israel and China. The mass of bromine in the oceans is about one three-hundredth of that of chlorine.
Bromine is sparingly soluble in water. Organo bromine compounds are used as biocides, insecticides, and as a component of fire retardants.
Anion resin affinity for bromate increases with increasing size of the amine, therefore resins such as SIR-100 and SIR-110-HP have higher capacity for bromates than type I resins such as SBG1 or type II resins such as SBG2.
Bromide ions are quite soluble. Neutral bromide can be removed with strong base anion resins, acidic bromide solutions can also be removed by weakly basic anion resins such as WBMP.
Cadmium can be removed from plating rinse waters by deionization or by selective ion removal resins such as SIR-300 and WACMP-Na. Ideal pH is slightly acidic.
Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than other transition metals. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth’s crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.
Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange and yellow pigments, to colour glass, and to stabilize plastic. However, its use has fallen into disfavor due to its toxicity. Cadmium forms a divalent cation in water. Cadmium salts are mostly soluble.
At higher TDS, generic softening resins can still be used, albeit with lower capacity and higher leakage. With increasingly brackish feed it becomes necessary to use a worker and polisher arrangement or use a WAC resins such as WACMP instead of a SAC resin such as CG8.
SAC type resins are often effective to remove calcium from oil field produced waters. The customary arrangement is with a worker and polisher such that the brine is throughfared through the polisher first and then back through the worker.
The imminodiacetic chelating resin (SIR-300) and the amino phosphonic chelating resin (SIR-500) can be used to remove calcium from brine at any concentration. The amino phosphonic chelating resin is more commonly used for this purpose.
Generic strong acid cation resins are commonly used to remove hardness ions including calcium from potable water. Soft water protects hot water heaters from scale and helps soaps to function without leaving a soap scum. Calcium and other hardness ions are exchanged for sodium (or in some cases potassium). The resins can be used over and over following regeneration with salt brine.
Californium is a radioactive metallic chemical element with symbol Cf and atomic number 98. The element was first made in 1950 at the University of California Radiation Laboratory in Berkeley, by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium). The element was named after the university and the state of California.
Two crystalline forms exist for californium under normal pressure: one above and one below 900 °C (1,650 °F). A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Compounds of californium are dominated by a chemical form of the element, designated californium(III), that can participate in three chemical bonds. The most stable of californium’s twenty known isotopes is californium-251, which has a half-life of 898 years. This short half-life means the element is not found in significant quantities in the Earth’s crust.
Californium is a neutron emitter and is used in certain specialized material testing and as an accelerator for nuclear chain reactions. World supply is approx. 0.25 grams per year.
Carbon (from Latin: carbo “coal”) is a chemical element with symbol C and atomic number 6. It is nonmetallic one of the most versatile of elements due to its propensity to form tetravalent covalent bonds. Three isotopes occur naturally, 12C and 13C being stable while 14C is radioactive, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.
Carbon is the 15th most abundant element in the Earth’s crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon’s abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life. It is the second most abundant element in the human body by mass (about 18.5%) after oxygen.
Pure carbon exists in a variety of forms, from diamond to graphite.
Carbon dioxide gas can be captured by strong base anions in the hydroxide form. Spent resin is regenerated thermally, driving CO2 back off the resin.
Hydroxide for anion resins exchange for carbon dioxide by a neutralization reaction to carbonate, followed by exchange of carbonate.
Carbonate is a form of alkalinity (along with bicarbonate and carbon dioxide). Carbonates readily combine with many divalent cations (especially calcium) to form a precipitant. Calcium carbonate precipitation is quite common in waters where the pH is > 9. Carbonate can be removed by various strong base anion resins and can be neutralized (acidified) by various cation resins.
Cerium is a soft, ductile, silvery-white metallic chemical element with symbol Ce and atomic number 58. Tarnishing rapidly when exposed to air, it is soft enough to be cut with a knife. Cerium is the second element in the lanthanide series, and while it often shows the +3 state characteristic of the series, it also exceptionally has a stable +4 state that does not oxidise water. It is also traditionally considered to be the most abundant of the rare earth elements. Cerium has no biological role, and is not very toxic.
Despite always being found in combination with the other rare earth elements in minerals such as monazite and bastnäsite, cerium is easy to extract from its ores, as it can be distinguished among the lanthanides by its unique ability to be oxidised to the +4 state. It is the most common of the lanthanides, followed by neodymium, lanthanum, and praseodymium. It is the 26th most abundant element, making up 66 ppm of the Earth’s crust, half as much as chlorine and five times as much as lead.
If it is ionized it is typically present as a trivalent cation. Cerium oxide is used as an abrasive, as a redox catalyst, and in advanced oxidation systems. Cerium is also used in various pigments and in catalytic converters.
Trace quantities of cerium can be removed from water effectively with salt regenerated SAC resins such as CGS, CG8, CG10 etc. Brine can be used to effectively regenerate cerium off the resin.
Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28.5 °C (83.3 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is the least electronegative element. It has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especially caesium-137, a fission product, are extracted from waste produced by nuclear reactors.
The German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a “getter” in vacuum tubes and in photoelectric cells. In 1967, acting on Einstein’s proof that the speed of light is the most constant dimension in the universe, the International System of Units used two specific wave counts from an emission spectrum of caesium-133 to co-define the second and the metre. Since then, caesium has been widely used in highly accurate atomic clocks.
Metallic cesium is highly reactive in both air and especially in water, reacting explosively, even temperatures as low as −116 °C (−177 °F). Cesium exclusively forms a monovalent cation. Almost all cesium salts are readily soluble in water.
SIR-600 has extremely high selectivity for cesium. Cesium is captured by molecular sieving in addition to in exchange. Hydrogen form cation resins such as CG8-H can also be used but their ability to remove cesium is limited by other ions in solution. In general when using SAC type resins to remove cesium it is necessary to remove all the other cations along with cesium.
The main source of chlorate in potable water is from the use of sodium hypochlorite bleach as a disinfectant. Chlorate forms as sodium hypochlorite bleach decomposes. Chlorate is strongly preferred by strong base anion resins, particularly those with higher amines. Useful capacities are obtained with chloride form strong base anion resin that are regenerated with salt.
Salt form strong base anion resin can be effectively used for chloride removal. However, as the resin is generally sold in the chloride form the user must either specify bicarbonate form or must regenerate the resin into the chloride form prior to first use.
Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity, behind only oxygen and fluorine.
The most common compound of chlorine, sodium chloride (common salt), has been known since ancient times. Around 1630, chlorine gas was first synthesised in a chemical reaction, but not recognised as a fundamentally important substance. Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be a pure element, and this was confirmed by Sir Humphry Davy in 1810, who named it from Ancient Greek: χλωρός khlôros “pale green” based on its colour.
Chlorine is normally present in water as hypochlorous anion and is removed by strong base anion resins.
(Sodium) hypochlorite is widely used as a bleaching agent; in water treatment as a disinfectant. It is the strongest oxidant among the oxo-chloride series, chlorite, chlorate, or perchlorate.
Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is an oxidizing agent, able to transfer oxygen to a variety of substrates, while gaining one or more electrons via oxidation-reduction (redox). It does not hydrolyze when it enters water, and is usually handled as a dissolved gas in solution in water. Potential hazards with chlorine dioxide include health concerns, explosiveness and fire ignition.
Chlorine dioxide has been widely used for bleaching purposes in the paper industry, and for treatment of drinking water. It is generally more effective than chlorine or hypochlorite bleach because it remains a gas dissolved in water and can diffuse through the cell wall of bio growths where it disrupts the cell itself. More recent developments have extended its application into food processing, disinfection of premises and vehicles, mold eradication, air disinfection and odor control, treatment of swimming pools, dental applications, and wound cleansing.
Sodium chlorite is a powerful oxidizer primarily used as a precursor to producing chlorine dioxide. ClO2 has advantages over hypochlorite because it produces far fewer THMs and also remains a gas when dissolved in water, allowing it to penetrate bio growths by diffusion.
Chromium is a chemical element with symbol Cr and atomic number 24. It is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
Ferrochromium alloy is commercially produced from chromite by silicothermic or aluminothermic reactions; and chromium metal by roasting and leaching processes followed by reduction with carbon and then aluminium. Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating (electroplating with chromium) together comprise 85% of the commercial use.
Low levels of chromium can leach out of chrome platings and from stainless steel. Dissolved chromium may be cationic (tri chrome) or an ionic (hex chrome) depending on pH and redox potential.
SIR-700 is best choice provided pH can be reduced, otherwise SBG2 or SBG1 may be better choices. SIR-700 is intended for single use and when pH is lowered to approx. 5.5 the throughput can be 100’s of thousands of bed volumes. SBG1 and SBG2 are brine regenerated and throughput depends primarily on competition from sulfate. * Note that Chromate is often reported “as Cr” which means the mwt is 52 and the equivalent weight is 26.
Divalent metallic contaminants such as copper, iron, zinc etc. can be removed from trivalent chromium (chromic acid) type plating baths, thereby extending the useful life of the bath.
Trivalent chromium is cationic and can be removed by a variety of cation exchange resins.
Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth’s crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought by alchemists to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes upon smelting. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.
Today, some cobalt is produced specifically from various metallic-lustered ores, for example cobaltite (CoAsS), but the main source of the element is as a by-product of copper and nickel mining.
Cobalt primarily forms a divalent cation in water and is relatively soluble. Cobalt readily forms coordinate covalent bonds (chelating type) and is often found in organic complexes or as a zero valent colloidal solid.
Cationic cobalt, used in plating solutions, can be removed by a variety of cation resins, depending on pH and TDS.
Colloidal cobalt is removed by a combination of static attraction and ion exchange.
Copernicium is a chemical element with symbol Cn and atomic number 112. It is an extremely radioactive synthetic element that can only be created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds. Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the astronomer Nicolaus Copernicus.
During reactions with gold, it has been shown to be an extremely volatile metal, so much so that it is probably a gas at standard temperature and pressure.
Copernicium has also been calculated to possibly show the oxidation state +4, while mercury shows it in only one compound of disputed existence and zinc and cadmium do not show it at all, although more recent calculations cast doubt on this possibility. It has also been predicted to be more difficult to oxidize copernicium from its neutral state than the other group 12 elements. Copernicium is so unstable and so little has ever been made that its chemical and physical properties have not been studied.
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a reddish-orange color. It is used as a conductor of heat and electricity, as a building material and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins and constantan used in strain gauges and thermocouples for temperature measurement.
Copper is one of few metals that occur uncombined in nature and this was the first source of the metal to be used by humans, c. 8000 BC. It was the first metal to be smelted from its ore, c. 5000 BC, the first metal to be cast into a shape in a mold, c. 4000 BC and the first metal to be purposefully alloyed with another metal, tin, to create bronze, c. 3,500 BC.
Copper is an essential trace nutrient and an extremely useful metal. Copper primarily forms a divalent cation in water. However copper complexes with ammonia to form a monovalent cation and is also found as a zerovalent species and in organic complexes
Copper is most commonly found in potable water as a divalent cation, the result of corrosion of copper piping. Copper corrosion is exacerbated by the presence of ammonia and also from galvanic cells set up when dissimilar piping materials are directly connected to each other.
Copper chloride forms a complex anion when chloride concentrations are high. Copper chloride can be removed by various strong base anion resins such as SBG1. Regeneration is accomplished with water, which reduces chloride concentration and breaks the complex anion back into cation copper.
Strong base anion resins such as SBG1 have high selectivity for cyanide complexes such as copper cyanide. Removal capacity is often quite high, depending on TDS and mix of other anions present.
Curium is a transuranic radioactive chemical element with symbol Cm and atomic number 96. This element of the actinide series was named after Marie and Pierre Curie – both were known for their research on radioactivity. Curium was first intentionally produced and identified in July 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley. The discovery was kept secret and only released to the public in November 1945. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 20 grams of curium.
Curium is a hard, dense, silvery metal with a relatively high melting point and boiling point for an actinide. Whereas it is paramagnetic at ambient conditions, it becomes antiferromagnetic upon cooling, and other magnetic transitions are also observed for many curium compounds. In compounds, curium usually exhibits valence +3 and sometimes +4, and the +3 valence is predominant in solutions. Curium readily oxidizes, and its oxides are a dominant form of this element.
Curium is primarily used is as a precursor to transmute Pu238 used as a power source for space exploration vehicles ad in spy devices
Free cyanide is readily converted to cyanate (less toxic) with bleach or other oxidants, with more difficulty to carbonate. Combined cyanides have high selectivity for strong base anion resins and can be difficult to remove from resin once they have exchanged.
Dubnium is a chemical element with symbol Db and atomic number 105. A transactinide element, dubnium is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of just above a day. This greatly limits the extent of possible research on dubnium.
Dubnium does not naturally occur on Earth and must be produced artificially. There are no known commercial uses, its manufacture was driven by a desire to find and name remaining elements in the periodic table.
Dysprosium is a chemical element with the symbol Dy and atomic number 66. Dysprosium is never found in nature as a free element, though it is found in various minerals, such as xenotime. Naturally occurring dysprosium is composed of seven isotopes, the most abundant of which is 164Dy.
Dysprosium was first identified in 1886 by Paul Émile Lecoq de Boisbaudran, but was not isolated in pure form until the development of ion exchange techniques in the 1950s. Dysprosium is a rare earth element that has a metallic, bright silver luster. It is soft enough to be cut with a knife, and can be machined without sparking if overheating is avoided. Dysprosium’s physical characteristics can be greatly affected by even small amounts of impurities.
Dysprosium is used, in conjunction with vanadium and other elements, in making laser materials and commercial lighting. Because of dysprosium’s high thermal-neutron absorption cross-section, dysprosium-oxide–nickel cermets are used in neutron-absorbing control rods in nuclear reactors. Dysprosium–cadmium chalcogenides are sources of infrared radiation, which is useful for studying chemical reactions. Because dysprosium and its compounds are highly susceptible to magnetization, they are employed in various data-storage applications, such as in hard disks. Dysprosium is increasingly in demand for the permanent magnets used in electric-car motors and wind-turbine generators. It has high neutron absorption but is less prevalent than gadolinium, ore commonly used for this purpose in nuclear reactors.
Soluble dysprosium salts are mildly toxic, while the insoluble salts are considered non-toxic.
Einsteinium is a synthetic element with symbol Es and atomic number 99. It is the seventh transuranic element, and an actinide.
Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein. Its most common isotope einsteinium-253 (half life 20.47 days) is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. The reactor synthesis is followed by a complex process of separating einsteinium-253 from other actinides and products of their decay. Other isotopes are synthesized in various laboratories, but at much smaller amounts, by bombarding heavy actinide elements with light ions. Owing to the small amounts of produced einsteinium and the short half-life of its most easily produced isotope, there are currently almost no practical applications for it outside of basic scientific research. In particular, einsteinium was used to synthesize, for the first time, 17 atoms of the new element mendelevium in 1955.
It has no known commercial uses.
Erbium is a chemical element with symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements on Earth. As such, it is a rare earth element which is associated with several other rare elements in the mineral gadolinite from Ytterby in Sweden, where yttrium, ytterbium, and terbium were discovered.
Erbium’s principal uses involve its pink-colored Er3+ ions, which have optical fluorescent properties particularly useful in certain laser applications. Erbium-doped glasses or crystals can be used as optical amplification media, where Er3+ ions are optically pumped at around 980 or 1480 nm and then radiate light at 1530 nm in stimulated emission. This process results in an unusually mechanically simple laser optical amplifier for signals transmitted by fiber optics. The 1550 nm wavelength is especially important for optical communications because standard single mode optical fibers have minimal loss at this particular wavelength. In water it typically forms a trivalent cation.
Europium is a chemical element with symbol Eu and atomic number 63. It is a moderately hard, silvery metal which readily oxidizes in air and water. Europium usually assumes the oxidation state +3, but the oxidation state +2 is also common. All europium compounds with oxidation state +2 are slightly reducing. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the least abundant elements in the universe; only about 5×10−8% of all matter in the universe is europium.
Europium is a ductile metal with a hardness similar to that of lead. It crystallizes in a body-centered cubic lattice. Europium is relatively non toxic compared to other heavy metals. It is quite rare, has no biological role and few commercial uses.
Fermium is a synthetic element with symbol Fm and atomic number 100. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared.
It was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside of basic scientific research.
Ferrocyanide is relatively non toxic because it is quite stable and does not readily release cyanide. Ferric ferrocyanide forms the intensely blue dye “Prussian blue”. Potassium ferrocyanide is used as an anticaking agent, notably in some pelletized salt products.
Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.
Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the Latin verb fluo meaning “flow” became associated with it. Fluorine was first isolated using low-temperature electrolysis, a process still employed for modern production. Industrial production of fluorine gas for uranium enrichment, its largest application, began during the Manhattan Project in World War II.
Fluorine is never found uncombined and forms hydrofluoric acid when mixed with water.
Fluoride is deliberately added to most potable water supplies in the USA to help prevent dental carries (cavities). Although low concentration protect, higher concentration cause unsightly mottling. The USA MCL for fluoride is 4 mg/L.
Hydrofluoric acid is poorly ionized compared to other strong acids such as hydrochloric, nitric, sulfuric, etc. Very dangerous to handle due to extreme toxicity and adsorption thru the skin. Forms the fluorosilicic anion when sufficient silica is present. Etches glass and can diffuse through some plastics.
Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.
Bulk francium has never been viewed. Because of the general appearance of the other elements in its periodic table column, it is assumed that francium would appear as a highly reflective metal, if enough could be collected together to be viewed as a bulk solid or liquid. Obtaining such a sample is highly improbable, since the extreme heat of decay (the half-life of its longest-lived isotope is only 22 minutes) would immediately vaporize any viewable quantity of the element.
Francium is the second rarest naturally occurring element and was the last element first discovered in nature, rather than by synthesis. Its chemical and physical properties have not been studied.
Gadolinium is a chemical element with symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. It is found in nature only in combined (salt) form.
Gadolinium metal possesses unusual metallurgic properties, to the extent that as little as 1% gadolinium can significantly improve the workability and resistance to high temperature oxidation of iron, chromium, and related alloys. Gadolinium as a metal or salt has exceptionally high absorption of neutrons and therefore is used for shielding in neutron radiography and in nuclear reactors. Like most rare earths, gadolinium forms a trivalent cation in water with fluorescent properties and its salts are generally soluble. Gadolinium(III) salts have therefore been used as green phosphors in various applications.
Gallium is a chemical element with symbol Ga and atomic number 31. It is in group 13 of the periodic table, and thus has similarities to the other metals of the group, aluminium, indium, and thallium. Gallium does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores and in bauxite. Elemental gallium is a soft, silvery blue metal at standard temperature and pressure, a brittle solid at low temperatures, and a liquid at temperatures greater than 29.76 °C (85.57 °F) (slightly above room temperature). The melting point of gallium is used as a temperature reference point. The alloy galinstan (68.5% gallium, 21.5% indium, and 10% tin) has an even lower melting point of −19 °C (−2 °F), well below the freezing point of water.
Since its discovery in 1875, gallium has been used to make alloys with low melting points. It is also used in semiconductors as a dopant in semiconductor substrates.
Gallium is predominantly used in electronics manufacturing, especially LEDs. Gallium arsenide, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Gallium is also used in low melting point alloys and in “Environmentally friendly” thermometers due to its low toxicity.
Gallium arsenide can be decomposed and then the arsenic portion can be removed with arsenic selective medias such as ResinTech ASM-10-HP.
Germanium is a chemical element with symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. Pure germanium is a semiconductor with an appearance similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature. Unlike silicon, it is too reactive to be found naturally on Earth in the free (elemental) state.
Because it seldom appears in high concentration, germanium was discovered comparatively late in the history of chemistry. Germanium ranks near fiftieth in relative abundance of the elements in the Earth’s crust.
Germanium is used instead of silicon in high end semiconductors such as LED’s and solar panels.
Germanium forms covalent compounds that are mostly not ionized. It is a semiconductor in the same group as silicon. Current uses include fiber optics and night vision goggles.
Gold is a chemical element with the symbol Au and the atomic number 79. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable and ductile metal. It is one of the least reactive chemical elements, and is solid under standard conditions. The metal therefore occurs often in free elemental (native) form, as nuggets or grains, in rocks, in veins and in alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum) and also naturally alloyed with copper and palladium. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).
Gold’s atomic number of 79 makes it one of the higher atomic number elements that occur naturally in the universe. It is thought to have been produced in supernova nucleosynthesis and from the collision of neutron stars and to have been present in the dust from which the Solar System formed.
Gold is corrosion resistant and considered a precious meta. It is used primarily in jewelry and as an investment object.
Gold chloride is sometimes used in “electroless” plating applications.
Alkaline cyanide plating is the most common gold plating method.
Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray metal, hafnium has a high neutron capture cross section making it useful in certain nuclear applications. Hafnium is the sister metal of zirconium and has similar properties.
Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.Hafnium’s large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.
If ionized in water, Hafnium forms a tetravalent cation.
Hassium is a chemical element with symbol Hs and atomic number 108. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, 269Hs, has a half-life of approximately 9.7 seconds, although an unconfirmed metastable state, 277mHs, may have a longer half-life of about 130 seconds. More than 100 atoms of hassium have been synthesized to date. It is synthesized by fusing two lighter elements together.
Chemistry experiments have confirmed that hassium behaves as the heavier homologue to osmium. The chemical properties of hassium are characterized only partly, but they compare well with the chemistry of the other group 8 elements. In bulk quantities, hassium is expected to be a silvery metal that reacts readily with oxygen in the air, forming a volatile tetroxide.
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements.
After hydrogen, helium is the second lightest and second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this figure in the Sun and in Jupiter. This is due to the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium.
This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, and is believed to have been formed during the Big Bang. Large amounts of new helium are being created by nuclear fusion of hydrogen in stars.
Helium is used in cryogenics, inert gas welding and in lighter than air balloons and blimps.
Holmium is a chemical element with symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a rare earth element. Elemental holmium is a relatively soft and malleable silvery-white metal. It is too reactive to be found uncombined in nature, but when isolated, is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and will also burn in air when heated.
Holmium is found in the minerals monazite and gadolinite, and is usually commercially extracted from monazite using ion exchange techniques. Its compounds in nature, and in nearly all of its laboratory chemistry, form a trivalent cation, containing Ho(III) ions. Trivalent holmium ions have fluorescent properties similar to many other rare earth ions (while yielding their own set of unique emission light lines), and holmium ions are thus used in the same way as some other rare earths in certain laser and glass colorant applications.
Holmium strongly absorbs neutrons and is used as a “burnable poison” in nuclear reactors. Holmium also has the highest magnetic permeability of any element and is used as the polepiece in some static magnets. Most holmium salts are quite soluble.
Hydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest element on the periodic table.
Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. Non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium (name rarely used, symbol 1H), has one proton and no neutrons.
The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H2. Since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms combined with oxygen to form water or with carbon to form organic compounds.
Hydronium (hydrogen) is the acid that forms when water ionizes. Hydrogen ions lower pH. Hydrogen ions take part in many chemical reactions and are useful in ion exchange applications as a source of counter ion for cation resins.
Tritiated water can be removed into the water of hydration by aluminum form strong acid cation resin.
Hydroxide alkalinity is the base that forms when water ionizes. Hydroxide ions increase pH. Hydroxides take part in many chemical reactions and are useful in ion exchange applications as a source of counter ion for anion resins.
Indium is a chemical element with symbol In and atomic number 49. It is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Very soft and malleable, Indium has a melting point higher than sodium and gallium, but lower than lithium or tin. Ferdinand Reich and Hieronymous Theodor Richter discovered it with spectroscopy in 1863, naming it for the indigo blue line in its spectrum. It was isolated the next year.
Chemically, indium is similar to gallium and thallium, and it is largely intermediate between the two in terms of its properties. It is a minor component in zinc sulfide ores and is produced as a byproduct of zinc refinement. It is most notably used in the semiconductor industry, in low-melting-point metal alloys such as solders, in soft-metal high-vacuum seals, and in the production of transparent conductive coatings of indium tin oxide (ITO) on glass. Indium has no biological role, though its compounds are somewhat toxic when injected into the bloodstream. Most occupational exposure is through ingestion, from which indium compounds are not absorbed well, and inhalation, from which they are moderately absorbed.
Radioactive iodine is a manmade isotope with properties similar to other isotopes of iodine. Radio-iodine is present in water as iodide. As a trace ion it can be removed by various types of strong base anion resins, favoring the higher amines. Silver and silver impregnated medias show increased affinity for iodides.
Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas. The elemental form was discovered by the French chemist Bernard Courtois in 1811.
Iodine occurs in many oxidation states, including iodide (I−), iodate (IO−3), and the various periodate anions. It is the least abundant of the stable halogens, being the sixty-first most abundant element. It is even less abundant than the so-called rare earths. It is the heaviest essential element. Iodine is found in the thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.
The dominant producers of iodine today are Chile and Japan. Iodine and its compounds are primarily used in nutrition and sometimes added to water as a disinfectant. Although not present as an ion, iodine complexes with strong base anion resin and is removed. Iodinated anion exchange resin is sometimes used as a controlled release form of iodine as a disinfectant for contaminated water supplies.
Iodate is a highly oxidized form of iodine where the iodine atom has a +5 valence. Iodate is used in titration methods for determination of various redox species.
Iodide preference by strong base anion resins increases with the size of the amine, tributylamine having roughly ten times the preference of trimethylamine.
Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable.
Iridium was discovered in 1803 among insoluble impurities in natural platinum. Smithson Tennant, the primary discoverer, named iridium for the Greek goddess Iris, personification of the rainbow, because of the striking and diverse colors of its salts. Iridium is one of the rarest elements in Earth’s crust, with annual production and consumption of only three tonnes. 191Ir and 193Ir are the only two naturally occurring isotopes of iridium, as well as the only stable isotopes; the latter is the more abundant of the two.
Iridium forms complex anions in the presence of high concentrations of halogens and cyanides but does not react with acids, salts, or bases.
Iron is a chemical element with symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the iron into space.
Like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, exposing fresh surfaces for corrosion.
Iron metal has been widely used since ancient times as a building material. Iron has an important biological role in transport of oxygen via hemoglobin.
Strong base anion resins in the chloride form are effective to remove traces of iron from hydrochloric acid or other solutions with high chloride concentrations.
Ferric iron, most commonly in the insoluble form of Fe2O3 (red) or Fe3O4 (black) can be filtered out of water by a variety of filtration methods. Ferric iron (in the form of ferric chloride) is commonly added to water as a coagulant. Ferric iron precipitants are sometimes used to help remove trace contaminants such as arsenic, selenium, etc.
Ferrous iron (sometimes known as clear water iron) can be removed by a variety of cation resin in either the sodium or hydrogen form.
Krypton (from Greek: κρυπτός kryptos “the hidden one”) is a chemical element with symbol Kr and atomic number 36. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. With rare exceptions, krypton is chemically inert.
Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single spectral line. Krypton fluoride also makes a useful laser. From 1960 to 1983, the official length of a meter was defined by the 605 nm wavelength of the orange spectral line of krypton-86, because of the high power and relative ease of operation of krypton discharge tubes.
Krypton is used in fluorescent lights and high powered lasers.
Lanthanum is a soft, ductile, silvery-white metallic chemical element with symbol La and atomic number 57. It tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. Lanthanum is the lightest of the rare earth elements. The usual oxidation state is +3. Lanthanum has no biological role and is not very toxic.
Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Ancient Greek λανθάνειν (lanthanein), meaning “to lie hidden”. Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth’s crust, almost three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum composes about a quarter of the lanthanide content. It is extracted from those minerals by a process of such complexity that pure lanthanum metal was not isolated until 1923.
Unlike cerium and other rare earths, lanthanum does not form complexes with HCl. Lanthanum compounds are used as catalysts and in a variety of specialty applications including adsorbents for contaminants such as arsenic.
Lawrencium is a synthetic chemical element with chemical symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements.
A radioactive metal, lawrencium is the eleventh transuranic element and is also the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Twelve isotopes of lawrencium are currently known; the most stable is 266Lr with a half-life of 11 hours, but the shorter-lived 260Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale.
Chemistry experiments have confirmed that lawrencium behaves as a heavier homolog to lutetium in the periodic table, and is a trivalent element. It thus could also be classified as the first of the 7th-period transition metals: however, its electron configuration is anomalous for its position in the periodic table, having an s2p configuration instead of the s2d configuration of its homolog lutetium.
Lead (/lɛd/) is a chemical element with atomic number 82 and symbol Pb (from Latin: plumbum). It is a soft, malleable, and heavy metal. Freshly cut solid lead has a bluish-white color that soon tarnishes to a dull grayish color when exposed to air; the liquid metal has shiny chrome-silver luster. Lead’s density of 11.34 g/cm3 exceeds that of most common materials. Lead has the second highest atomic number of all practically stable elements. As such, lead is located at the end of some decay chains of heavier elements, which in part accounts for the relative abundance of lead: it exceeds those of other similarly-numbered elements.
Lead is a post-transition metal, and is relatively inert unless powdered. Its weakened metallic character is illustrated by its general amphoteric nature: it and its oxides react with both acids and bases. It also displays a marked tendency toward covalent bonding. Its compounds are most commonly found in the +2 oxidation state, rather than +4, unlike the lighter group 14 elements.
Lead is the heaviest stable element. At one time lead was widely used in paints and as an octane booster for gasoline. However, issues with toxicity have sharply curtailed its use.
Lead in potable water that is present in its ionic form can be removed by a variety of cation exchange resins including both strong acid and weak acid types. Lead is not soluble in waters with significant alkalinity and at pH above 8. In the environment, lead complexes with naturally occurring organic matter.
Lithium (from Greek: λίθος lithos, “stone”) is a chemical element with the symbol Li and atomic number 3. It is a soft, silver-white metal belonging to the alkali metal group of chemical elements.
Under standard conditions, it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable. For this reason, it is typically stored in mineral oil. When cut open, it exhibits a metallic luster, but contact with moist air corrodes the surface quickly to a dull silvery gray, then black tarnish.
Because of its high reactivity, lithium never occurs freely in nature, and instead, appears only in compounds, which are usually ionic. Lithium occurs in a number of pegmatitic minerals, but due to its solubility as an ion, is present in ocean water and is commonly obtained from brines and clays. On a commercial scale, lithium is isolated electrolytically from a mixture of lithium chloride and potassium chloride.
Lithium’s strong electropositivity make it useful for batteries and in organic synthesis. The largest uses of lithium compounds is as an additive to ceramics and glazes.
Lithium 7 isotope has a very small neutron cross sectional area, making it useful as the counterion for borate salts used in nuclear reactors.
Lithium compounds are widely used in manufacture of high energy density batteries, as well as lubricants and ceramics. Lithium salts have mood stabilizing medicinal properties.
Lutetium is a chemical element with symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry, but not in moist air. It is the last element in the lanthanide series, and is traditionally counted among the rare earths.
Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these researchers found lutetium as an impurity in the mineral ytterbia, which was previously thought to consist entirely of ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain, as he had published his results earlier. He chose the name lutecium for the new element, but in 1949 the spelling of element 71 was changed to lutetium.
Lutetium is sometimes used as a tracer for determining the age of minerals and meteorites.
Magnesium is a chemical element with symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (Group 2, or alkaline earth metals) of the periodic table: all Group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.
Magnesium is the ninth most abundant element in the universe. It is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the interstellar medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earth’s crust and the fourth most common element in the Earth (after iron, oxygen and silicon), making up 13% of the planet’s mass and a large fraction of the planet’s mantle. It is the third most abundant element dissolved in seawater, after sodium and chlorine.
Magnesium metal is a strong and light metal used in manufacturing engine blocks, aircraft parts and in aluminum magnesium alloys.
Magnesium ions can be removed from brine using either the iminodiacetic or aminophosphonic type chelating resins.
Magnesium is readily removed by sodium form strong acid cation resins at modest TDS .
Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as a free element in nature; it is often found in minerals in combination with iron.
Historically, manganese is named for various black minerals (such as pyrolusite) from the same region of Magnesia in Greece which gave names to similar-sounding magnesium, Mg, and magnetite, an ore of the element iron, Fe. By the mid-18th century, Swedish chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite (now known to be manganese dioxide) contained a new element, but they were unable to isolate it. Johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon.
Manganese phosphating is used for rust and corrosion prevention on steel. Ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions.
Although manganese metal is almost never used, manganese is an important alloy in the manufacture of stainless steel. Manganese compounds have wide use and manganese dioxide is a common redox media.
Manganese can be removed by water softening resins, provided oxygen is excluded from the water so that manganese remains a divalent cation.
Manganese dioxide is used as a redox media to enhance the oxidation of iron and (soluble) manganese.
Permanganate is used as a disinfectant in potable waters because it produces much lower levels of disinfection by-products than does chlorine or bleach. Permanganate is also used as an oxidant in redox filters for the removal or iron and manganese.
Mendelevium is a synthetic element with chemical symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities through neutron bombardment of lighter elements. It is the third-to-last actinide and the ninth transuranic element. It can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of sixteen mendelevium isotopes are known, the most stable being 258Md with a half-life of 51 days; nevertheless, the shorter-lived 256Md (half-life 1.27 hours) is most commonly used in chemistry because it can be produced on a larger scale.
Mendelevium was discovered by bombarding einsteinium with alpha particles in 1955, the same method still used to produce it today. It was named after Dmitri Mendeleev, father of the periodic table of the chemical elements. Mendelevium is made by bombarding einsteinium with alpha particles.
Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum. A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element’s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments.
Mercury forms amalgams with many metals and was once used in dental fillings and to extract gold from various ores. Mercury is still used as a preservative in vaccines despite its know toxicity. Commercial uses of mercury have been curtailed, however mercury emissions from coal fired power plants remain a dominant source of mercury in our environment.
Mercury is a potent neurotoxin. Most mercury in our environment currently comes from coal fired power plants. Aerosol mercury emissions remain in the upper atmosphere for long periods of time, making this a global problem. The selective resins with thiol functionality have high affinity for cationic mercury.
Organo mercury compounds, notably methyl mercury form from the reaction of elemental or cationic mercury with organic matter.
Molybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.
Molybdenum does not occur naturally as a free metal on Earth; it is found only in various oxidation states in minerals. The free element, a silvery metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys.
Most molybdenum compounds have low solubility in water, but when molybdenum-bearing minerals contact oxygen and water, the resulting molybdate ion is quite soluble.
Molybdate, although less effective than chromate, is commonly used in closed loop cooling systems, as corrosion inhibitor. Molybdates are also as catalysts and in lubricants.
Neodymium is a chemical element with symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities in the ore minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Although neodymium is classed as a rare earth, it is a fairly common element, no rarer than cobalt, nickel, and copper, and is widely distributed in the Earth’s crust. Most of the world’s commercial neodymium is mined in China.
Neodymium compounds were first commercially used as glass dyes in 1927, and they remain a popular additive in glasses. The color of neodymium compounds—due to the Nd3+ ion—is often a reddish-purple but it changes with the type of lighting, due to the interaction of the sharp light absorption bands of neodymium with ambient light enriched with the sharp visible emission bands of mercury, trivalent europium or terbium. Some neodymium-doped glasses are also used in lasers that emit infrared with wavelengths between 1047 and 1062 nanometers. These have been used in extremely-high-power applications, such as experiments in inertial confinement fusion.
Neodymium readily oxidizes to form a trivalent cation. Most Neodymium salts are water soluble.
Neon is a chemical element with symbol Ne and atomic number 10. It is in group 18 (noble gases) of the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypton and xenon) in 1898 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon and carbon dioxide were removed. Neon was the second of these three rare gases to be discovered, and was immediately recognized as a new element from its bright red emission spectrum. The name neon is derived from the Greek word, νέον, neuter singular form of νέος (neos), meaning new. Neon is chemically inert and forms no uncharged chemical compounds. The compounds of neon include ionic molecules, molecules held together by van der Waals forces and clathrates.
During cosmic nucleogenesis of the elements, large amounts of neon are built up from the alpha-capture fusion process in stars. Although neon is a very common element in the universe and solar system (it is fifth in cosmic abundance after hydrogen, helium, oxygen and carbon), it is very rare on Earth. It composes about 18.2 ppm of air by volume (this is about the same as the molecular or mole fraction), and a smaller fraction in Earth’s crust.
Neon emits and orange/red light when placed in an electric field and is used in lights and lasers.
Neptunium is a chemical element with symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. It is radioactive, poisonous, pyrophoric, and can accumulate in bones, which makes the handling of neptunium dangerous.
Although many false claims of its discovery were made over the years, the element was first synthesized by Edwin McMillan and Philip H. Abelson at the Berkeley Radiation Laboratory in 1940. Since then, most neptunium has been and still is produced by neutron irradiation of uranium in nuclear reactors. The vast majority is generated as a by-product in conventional nuclear power reactors.
Neptunium in acidic solutions form either monovalent or divalent cations. In neutral to basic solutions it forms a trivalent anion or is insoluble.
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile. Pure nickel, powdered to maximize the reactive surface area, shows a significant chemical activity, but larger pieces are slow to react with air under standard conditions because an oxide layer forms on the surface and prevents further corrosion (passivation). Even so, pure native nickel is found in Earth’s crust only in tiny amounts, usually in ultramafic rocks, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth’s atmosphere.
Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth’s inner core.
Use of nickel (as a natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel’s hard, yet ductile, corrosion resistant characteristics make it usefule in high strength steel, copper nickel alloys, and in stainless steel.
Nickel salts are readily electroplated. Nickel sulfate and nickel sulfamate, often with boric acid as a pH stabilizer, are commonly used. Nickel in water is most commonly present as a divalent cation.
Traces of nickel can be found in potable waters as the corrosion product from nickel plated piping and fixtures. However, nickel is expensive and not commonly used.
Nickel production is often associated with solution mining. Nickel is extracted from the ore by acid and then purified by ion exchange.
Niobium, formerly columbium, is a chemical element with symbol Nb (formerly Cb) and atomic number 41. It is a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite. The name comes from Greek mythology: Niobe, daughter of Tantalus since it is so similar to tantalum.
Niobium has physical and chemical properties similar to those of the element tantalum, and the two are difficult to distinguish. The English chemist Charles Hatchett reported a new element similar to tantalum in 1801 and named it columbium. In 1809, the English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. The German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium. In 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element (as distinguished from tantalum), and for a century both names were used interchangeably. Niobium was officially adopted as the name of the element in 1949, but the name columbium remains in current use in metallurgy in the United States.
Niobium does not dissolve as a simple cation or anion and is found only in highly acidic mining wastes. If present in water it is most likely a complex anion.
Strong base anion resin have good affinity for nitrate. The higher amines (triethylamine, tributylamine, etc.) have increased affinity for nitrate and decreased affinity for divalent ions such as sulfate, making them preferred for many applications.
Nitrite is used as an antioxidant to preserve meats and as a pH stabilizer and corrosion inhibitor in cooling loops. Nitrite is removed by strong base anion resin but since its affinity is similar to that of chloride, throughput capacity is usually limited.
Nitrogen is a chemical element with symbol N and atomic number 7. It is the lightest pnictogen, and at room temperature it is a transparent, odorless diatomic gas. Nitrogen is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System.
Nitrogen is the most abundant element in Earth’s atmosphere, making up about 78% of the atmosphere by volume. It is essential to life as we know it. It is also the most common uncombined element on Earth, since all the more common elements occur primarily as compounds. The element nitrogen was discovered as a separable component of air by Scottish physician Daniel Rutherford in 1772.
Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong triple bond in elemental nitrogen (N≡N) dominates nitrogen chemistry, causing difficulty for both organisms and industry in converting the N2 into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds burn, explode, or decay back into nitrogen gas. Synthetically produced ammonia and nitrates are key industrial fertilizers, and fertilizer nitrates are key pollutants in the eutrophication of water systems.
Nitrogen in water is present as a dissolved gas.
Nitrous oxide has been used as an anesthetic and as a aerosol propellent. It is also used as an oxygen source in drag racing as well as a recreational intoxicant.
Nobelium is a synthetic chemical element with symbol No and atomic number 102. It is named in honor of Alfred Nobel, the inventor of dynamite and benefactor of science. A radioactive metal, it is the tenth transuranic element and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of twelve nobelium isotopes are known to exist; the most stable is 259No with a half-life of 58 minutes, but the shorter-lived 255No (half-life 3.1 minutes) is most commonly used in chemistry because it can be produced on a larger scale.
Chemistry experiments have confirmed that nobelium behaves as a heavier homolog to ytterbium in the periodic table. The chemical properties of nobelium are not completely known: they are mostly only known in aqueous solution.
Nobelium is a radioactive transuranic element made by bombarding uranium with neon. It has no commercial uses outside of completing the periodic table.
Naturally occurring organic matter (NOM) is readily removed by strong base anion resins. Acrylic strong base resins and styrenic resins with high porosity work better because they are easier to regenerate.
Osmium (from Greek ὀσμή osme, “smell”) is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3. Its alloys with platinum, iridium, and other platinum-group metals are employed in fountain pen nibs, electrical contacts, and other applications where extreme durability and hardness are needed.
Osmium has a blue-gray tint and is the densest stable element, slightly denser than iridium. Calculations of density from the X-ray diffraction data may produce the most reliable data for these elements, giving a value of 22.562±0.009 g/cm3 for iridium versus 22.587±0.009 g/cm3 for osmium.
Osmium has a very low compressibility. It is a hard but brittle metal that remains lustrous even at high temperatures. Major uses of osmium tetroxide are staining specimens for electron microscopy and oxidation of alkenes in organic synthesis.
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal and oxidizing agent that readily forms oxides with most elements as well as other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20.8% of the Earth’s atmosphere. Additionally, as oxides the element also makes up almost half of the Earth’s crust.
Dioxygen is used in cellular respiration and many major classes of organic molecules in living organisms contain oxygen, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide.
Ozone is one the most powerful oxidizing agents known, far more potent that O2. In water treatment, ozone is used as a disinfectant and to promote oxidation reactions in advanced oxidation systems.
Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.
More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into less noxious substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification, chemical applications, groundwater treatment, and jewelry. Palladium is a key component of fuel cells, which react hydrogen with oxygen to produce electricity, heat, and water.
Palladium is fairly soluble compared to other platinum group metals and dissolves in a variety of acids, notable aqua regia.
Salts containing hexachloroplatinate are used in electroplating platinum.