Toxicant decomposition kinetics

Dahlin DC, Nelson SD (1982) Synthesis, decomposition kinetics, and preliminary toxicological studies of pure N-acetyl-p-benzoquinone imine, a proposed toxic metabolite of acetaminophen. J Med Chem 25 885-886... 

The kinetics of thermal decomposition and depolymerisation of various polymers is discussed. The aim of the study was to find reaction conditions where different polymers can be separated from mixtures by decomposing them into their monomers or into pyrolysis products and where chlorine and/or nitrogen are eliminated from the polymers without forming toxic compounds. Data are given for PVC, PS, PE, and PR 13 refs. 

Chemical/Physical. Emits toxic fumes of nitrogen oxides, cyanides, and chlorine when heated to decomposition (Sax and Lewis, 1987). Chlorothalonil is resistant to hydrolysis under acidic conditions. At pH 9, chlorothalonil (0.5 ppm) hydrolyzed to 4-hydroxy-2,5,6-trichloroisophthalo-nitrile and 3-cyano-2,4,5,6-tetrachlorobenzamide. Degradation followed first-order kinetics at a rate of 1.8% per day (Szalkowski and Stallard, 1977). 

IV. Characteristics of Steady Detonation V, Initiation Behavior VI. Deflagration-to-Detonation Transition (DDT) and Combustion VII. Decomposition and Kinetics VIII. Analytical Methods IX. Waste Disposal X. Toxicity XI. RDX Detonators XII. Military Specifications and XIII. References. Major emphasis will be placed on Sections IV, V, and VI... 

If similar rates apply to natural water/rock systems, which wilt generally have much longer residence times than considered in this study, we can expect that organic matter similar to G, will have disappeared (fi = 14 days). G2 kinetics will still be important. However, rates of decomposition of more recalcitrant organics (G r), because they include perhaps most of toxic organics, will still be important. 

The deposition of silver sulphide is detrimental as it contaminates the silver deposit and the solution, interferes with the kinetics of silver deposition and tends to cause chemical instability of the fixer. At extremely negative cathode potentials, cathodic decomposition of the fixer may result in emission of toxic hydrogen sulphide ... 

Chemical/Physical. The hydrolysis half-lives of oxamyl in a sterile 1% ethanol/water solution at 25°C and pH values of 4.5, 6.0, 7.0 and 8.0, were 300, 17, 1.6 and 0.20 weeks, respectively (Chapman and Cole, 1982). Under alkaline conditions, oxamyl hydrolyzed following first-order kinetics (Bromilow et al., 1980). Emits toxic finnes of nitrogen and sulfur oxides when heated to decomposition (Sax and Lewis, 1987). 

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