Poisoning silver

Unlabeled Uses Antimony poisoning, bismuth poisoning, selenium poisoning, silver poisoning, vanadium poisoning... 

Cyanide is foimd in many common honsehold items, such as rat and pest poisons, silver and metal polishes, photographic solntions, and fumigating products (Rumack and Lovejoy, in Amdnr et al., 1991, p. 933). Sodium and potassium cyanide can be readily purchased as chemicals, and are nsed in bulk in gold mining and the attendant separation or pniification operations. 

A typical catalyst bed is very shallow (10 to 50 mm) (76,77). In some plants the catalyst is contained in numerous small parallel reactors in others, catalyst-bed diameters up to 1.7 and 2.0 m (77,80) and capacities of up to 135,000 t/yr per reactor are reported (78). The silver catalyst has a useful life of three to eight months and can be recovered. It is easily poisoned by traces of transition group metals and by sulfur. 

Many silver compounds are unstable to light, and are thus shipped ia brown glass or opaque plastic bottles. Silver compounds that are oxidants, eg, silver nitrate and iodate, must be so identified according to U.S. Department of Transportation (DOT) regulations. Compounds such as silver cyanide, which is toxic owiag to its cyanide content, must carry a poison label. However, most silver compounds are essentially nontoxic. 

Catalyst lifetime for contemporary ethylene oxide catalysts is 1—2 years, depending on the severity of service, ie, ethylene oxide production rate and absence of feed poisons, primarily sulfur compounds. A large percentage (>95%) of the silver in spent catalysts can be recovered and recycled the other components are usually discarded because of thek low values. 

The metal-plating baths used are acidic copper sulfate and alkaline silver cyanide. Acid contamination ia the alkaline silver cyanide bath will release extremely poisonous hydrogen cyanide gas. Eor this reason, the two plating setups should be isolated from each other. Both plating baths should be weU... 

Metal compounds, particularly compounds of the heavy metals, have a history of importance as antimicrobial agents. Because of regulations regarding economic poisons in the environment they are no longer widely used in this appHcation. Mercury, lead, cadmium, uranium, and other metals have been imphcated in cases of poisoning that resulted in government response. The metals whose compounds have been of primary interest as antimicrobials are mercury, silver, and copper. 

Silver cyanide [506-64-9] M 133.9, m dec at 320 , d 3.95. POISONOUS white or grayish white powder. Stir thoroughly with H2O, filter, wash well with EtOH and dry in air in the dark. It is very insoluble in H2O (0.000023g in lOOmL H2O) but is soluble in HCN or aqueous KCN to form the soluble Ag(CN) complex. [Chem Ber 72 299 I939 J Am Chem Soc 52 184 1930.]... 

Mercury is used in the manufacture of thermometers, barometers and switchgear, and in the production of amalgams with copper, tin, silver and gold, and of solders. A major use in the chemical industry is in the production of a host of mercury compounds and in mercury cells for the generation of chlorine. Mercury has a significant vapour pressure at ambient temperature and is a cumulative poison. 

Arsen-saure, /, arsenic acid, -silber, n, silver arsenide, -silberblende,/, proustite, -spiegel, m. arsenic mirror, -suifid, n, arsenic sulfide, esp. the pentasulfide. -sulfur, n. arsenic trisulfide, arsenic(III) sulfide, -iir, n, (-ous) arsenide, -verbindung, /. arsenic compound, -vergiftung, /. arsenic poisoning, -wasser-stoff, m. arsenic hydride, arseniuretted hydrogen (specif, arsine, AsHa). -zink, n. zinc arsenide. 

Rausch-gelb, n. orpiment. -gift, n. narcotic poison or drug, -gold, n. Dutch gold, tinsel, -leder, n. chamois (leather), -mittel, n. intoxicant. -rot, n. realgar, -silber, n. imitation silver foil. 

A similar reaction was studied by Kowaka Jfi) who investigated the catalytic activity of palladium and its alloys with silver in the hydrogenation of ethylene. The author alluded to the poisoning effect of hydrogen pretreatment of the palladium catalyst. 

Attention has been given to the synthesis of bimetallic silver-gold clusters [71] due to their effective catalytic properties, resistance to poisoning, and selectivity [72]. Recently molecular materials with gold and silver nanoclusters and nanowires have been synthesized. These materials are considered to be good candidates for electronic nanodevices and biosensors [73]. 

Cadmium (Cd) anode cells are at present manufactured based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples. Thus wastewater streams from cadmium-based battery industries carry toxic metals cadmium, nickel, silver, and mercury, of which Cd is regarded the most hazardous. It is estimated that globally, manufacturing activities add about 3-10 times more Cd to the atmosphere than from natural resources such as forest fire and volcanic emissions. As a matter of fact, some studies have shown that NiCd batteries contribute almost 80% of cadmium to the environment,4,23 while the atmosphere is contaminated when cadmium is smelted and released as vapor into the atmosphere4 Consequently, terrestrial, aquatic, and atmospheric environments become contaminated with cadmium and remain reservoirs for human cadmium poisoning. 

Nowadays, most of the car manufacturers are interested to replace noble metals by cheaper active phases or at least to significantly lower their content without altering their tolerance to poisoning effects. Recent developments using gold and silver as active components specifically for low temperature applications could be promising, but their sulphur tolerance is questionable in those temperature conditions [12-14], Apparently, such an aspect may exclude an extensive development of those silver-based catalysts for NO abatement processes for stationary sources. 

Kachru DN, Tandon SK, Misra UK, et al. 1989. Occupational lead poisoning among silver jewelry workers. Indian J Med Sci 89-91. 

Silver W, Rodriguez-Torres R. 1968. Electrocardiographic studies in children with lead poisoning. Pediatrics 41 1124-1127. 

Yankel AJ, von Lindem IH, Walter SD. 1977. The Silver Valley lead study The relationship of childhood lead poisoning and environmental exposure. J Air Pollut Contr Assoc 27 763-767. 

Promoters may influence selectivity by poisoning undesired reactions or by increasing the rates of desired intermediate reactions so as to increase the yield of the desired product. If they act in the first sense, they are sometimes referred to as inhibitors. An example of this type of action involves the addition of halogen compounds to the catalyst used for oxidizing ethylene to ethylene oxide (silver supported on alumina). The halogens prevent complete oxidation of the ethylene to carbon dioxide and water, thus permitting the use of this catalyst for industrial purposes. 

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