Behavior in Natural Waters

The production of many organic compounds requires the chlorination of feedstock chemicals (Table 3.3). This yields untreated wastewater that contains significant amounts of chlorinated methanes, ethanes, propanes, ethylenes, and propylenes. Other related processes such as chlorohydrina-tion and oxychlorination result in similar wastewater products. Furthermore, the use of vinyl chloride in the production of acrylic fibers and polyvinyl chloride resins yields chlorinated ethanes and ethylenes, whereas the production of epoxy resins results in the formation of dichloropropane and dichloropropylene through the use of epichlorohydrin (Wise and Fahrent-hold, 1981). 

Evaporation is the primary route of loss of chloromethanes from water. At a concentration of 1 mg L of chloromethane, the half-life in water was determined to be 27 minutes at 200 rpm and 25 C (Dilling et ah, 1975). As expected, the evaporation rate increased with increasing rate of stirring. With occasional stirring, the half-life of structurally similar compounds such as trichloromethane, trichloroethane, 1,1,1-trichloroethane, and 1,1,1-chloromethane was approximately three times greater than that under stirred conditions (Dilling etah, 1975). It has to be emphasized here that extrapolation of laboratory results to natural situations (where the levels of chloromethanes are expected to be far less than 1 mg L ) is valid only for comparing relative rates of volatilization. These data show the preponder- 

Industrial product Industrial process Chemical feedstock Uncreated wastewater composition 

Carbon tetrachloride chlorination methane, ethylene dichloride chloromethanes, chloroethanes, chloroethylene 

Chloroform chlorination methane, methyl chloride chloromethanes, chloroethane, chloroethylenes 

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Applying the foregoing thermodynamic and kinetic information to manganese behavior in natural water systems is considerably limited because the manganese system exemplifies the difficulties discussed earlier. On the thermodynamic side, the kinds of oxide phases in natural waters may not correspond to those for which equilibrium data are available. Also, cation exchange reactions are probably important (21). On the kinetic side, the role of catalysis by various mineral surfaces in suspension or in sediments is not really known. Of considerable importance may be microbial catalysis of the oxidation or reduction processes, as described by Ehrlich (7). With respect to the real systems, relatively... 

Bruno J., Duro L., and Grive M. (2002) The applicability and limitations of thermodynamic geochemical models to stimulate trace element behavior in natural waters lessons from natural analogue studies. Chem. Geol. 190, 371-393. 

Which are the six or seven major elements that exhibit redox behavior in natural waters In what form do they occur under oxidizing and under reduced conditions ... 

Hydrolysis is an inq)ortant factor in actinide behavior in natural waters as the pH is high enough to result in such reactions as ... 

Choppin, GR., and B.E. Stout. 1989. Actinide behavior in natural waters. Sci. Total Environ. 83 203-216. 

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