Decomposition chemical contaminants

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials No reactions Stability During Transport Explosive decomposition when contaminated with peroxides formed by reaction with air Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Polymerization inhibited when stabilizer is used Inhibitor of Polymerization tert-Butylcatehol (0.01 -0.02%). 

As discussed above, there are two pathways to carry out HI decomposition, and the respective process steps are listed in table 4.3 and table 4.4. Construction materials development has focused on identifying materials that can withstand the different acids and chemicals at the processing conditions. HI, acid and vapor are present in both distillation processes, whereas H3PO4 is only used in extractive distillation. Hence, the following discussion of candidate construction materials for Section HI will be based on chemical contents instead of processing environment, as was the case for the other two sections. First, data for general corrosion will be reviewed, followed by the effects of stress corrosion and chemical contamination. 

Data on persistence of chemical agents indicate that attention should be given to potential effects on water supplies. Because it is unlikely that such contamination would occur, this is a secondary planning concern. In addition to the potential for water contamination from the primary agents, there is also potential for contamination by toxic decomposition products. Contamination of surface water bodies used as public water supplies would be of immediate concern. Groundwater supplies could also be affected if the agents migrate into the substrata. 

Photolysis has had limited application for treatment of hazardous waste or detoxification of chemically contaminated materials. The susceptibility of chlorinated aromatics, including herbicides such as 2,4-D and 2,4,5-T, to UV-induced decomposition is well established (7,8). Photodecomposition of such compounds leads to successive dechlorination followed by condensation reactions to form phenolic polymers (7,8). Other research has demonstrated that CDD and CDF decompose in the presence of UV light (8,9,10) Development of a photochemical process for destroying 2,3,7,8-TCDD in a waste tar indicated similar dechlorination and condensation reactions and products (8). The high-molecular weight end products, which are similar in structure to humic acids, would be expected to have low toxicity and mobility. Therefore, essentially complete... 

Most aroma chemicals are relatively high boiling (80—160°C at 0.4 kPa = 3 mm Hg) Hquids and therefore are subject to purification by vacuum distillation. Because small amounts of decomposition may lead to unacceptable odor contamination, thermal stabiUty of products and by-products is an issue. Important advances have been made in distillation techniques and equipment to allow routine production of 5000 kg or larger batches of various products. In order to make optimal use of equipment and to standardize conditions for distillations and reactions, computer control has been instituted. This is particulady well suited to the multipurpose batch operations encountered in most aroma chemical plants. In some instances, on-line analytical capabihty is being developed to work in conjunction with computer controls. 

Such solutions are necessarily contaminated with halide ions and with the products of any subsequent decomposition of the hypohalite anions themselves. Alternative routes are the electrochemical oxidation of halides in cold dilute solutions or the chemical oxidation of bromides and iodides ... 

Explosions involving flammable gases, vapours and dusts are discussed in Chapter 5. In addition, certain chemicals may explode as a result of violent self-reaction or decomposition when subjected to mechanical shock, friction, heat, light or catalytic contaminants. Substances containing the atomic groupings listed in Table 6.7 are known from experience to be thermodynamically unstable, or explosive. They include acetylides and acetylenic compounds, particular nitrogen compounds, e.g. azides and fulminates, peroxy compounds and vinyl compounds. These unstable moieties can be classified further as in Table 6.8 for peroxides. Table 6.9 lists a selection of potentially explosive compounds. 

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