Removal of Pesticides Residue in Produce with Ozonated Water Wash

摘要

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