Photodegradation of chlorpyrifos, malathion, and dimethoate by sunlight in the Sudan

The potential of sunlight photolysis in remediation of pesticide-polluted soils in Sudan was studied. Chlorpyrifos, malathion and dimethoate, common pollutants, were exposed to sunlight over glass and soil surfaces with periodic samples drawn for GC and GC-MS analysis. Photo-degradation followed a biphasic model. Alpha half-lives of direct photolysis over glass surface range between 1.99 and 9.36days while the range in soil surfaces is 1.88-10.77days. Respective values for indirect photolysis with -carotene are 0.96-2.40days whereas for benzophenone are 0.38-2.37days (not including malathion as starting material was completely lost after 3days). Values for soil -carotene sensitized photolysis are 0.85-4.02days while respective values for soil benzophenone sensitized photolysis are 0.88-3.74days. Metrological factors did not have a significant impact on photolysis rates. No photoproducts detected in direct photolysis. However, many photoproducts were detected on the indirect sets. Photo-degradation efficiency can be ordered as; benzophenone>-carotene>direct exposure.