Biodegradable Replacement And Controlled Selfdestruction

Biodegradable substitutes have been developed for some hard pesticides. One approach is to substitute aromatic chlorine atoms in the DDT molecule (Anon., Chemical Week 109:36 1971). The new compounds reportedly do not build up in animal tissue and concentrate at higher levels in the food chain.

A mildly acid reduction by zinc will speed degradation of DDT and other pesticides in natural systems (EPA 1970). A copper catalyst speeds up the reduction. Effective degradation of DDT to bis(p-chlorophenyl) ethane appears possible in soil by using micron-sized particles of the re-ductant in close proximity to the DDT. Thin, slowly soluble wax or silyl coatings on the reductant can delay the reaction. A second technique for delayed reaction involves controlled air oxidation to sulfur to produce the required acidity. Effective degradation of DDT in aqueous systems was also achieved using reduction techniques. The procedure was reported effective in substantially degrading dieldrin, endrin, aldrin, chlordane, toxaphene, Kelthane, methoxychlor, Perthane and lindane.

0 0

Post a comment