Arsenic activators

Tanaka-Kagawa, T. et al., Arsenite and arsenate activate extracellular signal-regulated kinases 1/2 by an epidermal growth factor receptor-mediated pathway in normal human keratinocytes, Br. J. Dermatol., 149, 1116, 2003. 

In the patents of Brun (Ref 4), basic LSt was prepd by addg Pb nitrate to styphnic acid in the presence of NaOH. See also prepn reported by Hitchens Garfield (Ref 5) Properties of Basic LSt. Very few expl props of Basic LSt have been detd at Picatinny Arsenal Activation energy is 75.4kcal/mol, Ignition temp 295° for 5 sec value. It might be assumed that the expl props of Basic LSt are similar to those of the normal salt (qv)... 

Arsenic activities In fission products can be rapidly extracted Into benzene as the iodide from hydroiodic acid solution and then easily back extracted into water (l45). Dlls method Is a good, rapid separation from the germanium precursor and makes possible an exact determination of the fission yield of As78. 

Sundaram, S., Rathinasabapathi, B., Ma, L.Q., and Rosen, B.P. 2008. An arsenate-activated glutaredoxin from the arsenic hyperaccumulator fern Pteris vittata L. regulates intracellular arsenite. Journal of Biological Chemistry, 283 6095-101. 

Arsenate Activated No data No data Inhibited Inhibited... 

The Chemical Warfare Center included an Arsenal Operations Department which supervised strictly arsenal activities. As the new arsenals at Huntsville and Pine Bluff and later at Rocky Mountain got into operation, the nature of arsenal activities at Edgewood changed. These new arsenals took over the bulk of the arsenal operations in the CWS, and the Edgewood plants eventually assumed the role of pilot plants, in addition to handling a number of "blitz jobs. 

The chemistry of the H2S removal cycle is uniquely based on an arsenic-activated potassium carbonate solution, and is quite complex. The overall reaction mechanism of the absorption-regeneration cycle can be represented in a simplified form by the following equations ... 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

C. A. L. Westerdahl and co- oSk.cx.s Activated Gas Plasma SuTpace Treatment of Polymers for Adhesive Bonding, Part III, Technical Report 4279, Picatinny Arsenal, Dover, N.J., 1972. 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

Copper sulfate, in small amounts, activates the zinc dust by forming zinc—copper couples. Arsenic(III) and antimony(TTT) oxides are used to remove cobalt and nickel they activate the zinc and form intermetaUic compounds such as CoAs (49). Antimony is less toxic than arsenic and its hydride, stibine, is less stable than arsine and does not form as readily. Hydrogen, formed in the purification tanks, may give these hydrides and venting and surveillance is mandatory. The reverse antimony procedure gives a good separation of cadmium and cobalt. 

Three commercial processes that use these various hot carbonate flow arrangements are the promoted Benfield process, the Catacarb process, and the Giammarco-Vetrocoke process (26—29). Each uses an additive described as a promoter, activator, or catalyst, which increases the rates of absorption and desorption, improves removal efficiency, and reduces the energy requirement. The processes also use corrosion inhibitors, which aHow use of carbon—steel equipment. The Benfield and Catacarb processes do not specify additives. Vetrocoke uses boric acid, glycine, or arsenic trioxide, which is the most effective. 

Catalysts commonly lose activity in operation as a result of accumulation of materials from the reactant stream. Catalyst poisoning is a chemical phenomenon, A catalyst poison is a component such as a feed impurity that as a result of chemisorption, even in smaH amounts, causes the catalyst to lose a substantial fraction of its activity. For example, sulfur compounds in trace amounts poison metal catalysts. Arsenic and phosphoms compounds are also poisons for a number of catalysts. Sometimes the catalyst surface has such a strong affinity for a poison that it scavenges it with a high efficiency. The... 

Product specifications for microbial food enzymes have been estabUshed by JECEA and ECC. They limit or prescribe the absence of certain ubiquitous contaminants such as arsenic, heavy metals, lead, coliforms, E. coli and Salmonella. Furthermore, they prescribe the absence of antibacterial activity and, for fungal enzymes only, mycotoxins. 

Toxic heavy metals and ions, eg, Pb, Hg, Bi, Sn, Zn, Cd, Cu, and Fe, may form alloys with catalytic metals (24). Materials such as metallic lead, ziac, and arsenic react irreversibly with precious metals and make the surface unavailable for catalytic reactions. Poisoning by heavy metals ordinarily destroys the activity of a precious-metal catalyst (8). 

Metals in the platinum family are recognized for their ability to promote combustion at lowtemperatures. Other catalysts include various oxides of copper, chromium, vanadium, nickel, and cobalt. These catalysts are subject to poisoning, particularly from halogens, halogen and sulfur compounds, zinc, arsenic, lead, mercury, and particulates. It is therefore important that catalyst surfaces be clean and active to ensure optimum performance. 

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