Removal of Pesticides Residue in Produce withOzonated Water Wash

摘要

The objectives of the present study were to determine the susceptibility of theorganophosphrous pesticides such as malathion to ozonation. An aqueous model system wasdeveloped to study the effects of three pH values and chlorination on malathion degradationover a 30 min treatment period. Aqueous solutions buffered at pH 4.5, 7.0 and 10.7 wereprepared and used during testing. For ozonation study, ozone gas was bubbled into each pHsolutions doped with 4 ppm malathion. For the chlorination study, an appropriate amount ofcalcium hypochlorite stock solution was added to each pH solution to bring final chlorineconcentration to 50ppm. It was found that malathion degrade rapidly at pH 10.7. With the help ofozonation or chlorination, malathion can be completely degraded in strong alkaline solutions in 5min. Chlorination was slightly better than ozonation at pH 4.5. However, at pH 7, a neutral andpractical condition, ozonation performed better than chlorination in degrading malathion. Thetests on grapes indicate that ozonation was effective in removing and decomposing malathionsprayed on grapes.