Pesticide residue removal from vegetables by ozonation Original Research Article

A novel machine was developed to remove pesticide residues from vegetables using ozone. This domestic-scale vegetable cleaner consists of a closed cleaning chamber, an ozone generator, a water recirculation pump, and an oxidation–reduction potential (ORP) electrode. Two vegetables, Chinese white cabbage and green-stem bok choy, and three pesticides, permethrin (trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate), chlorfluazuron (1-[3,5-dichloro-4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenyl]-3-(2,6-difluorobenzoyl) urea), and chlorothalonil (tetrachloroisophthalonitrile) were used in tests. Cleaning for 15 min with pump recirculation removed 51% of chlorfluazuron and 53% of chlorothalonil. When the ozone production rate was 250 mg/h, removal efficiencies were 60% for chlorfluazuron and 55% for chlorothalonil, increases of 2–9% over pump recirculation only. When the ozone production rate was 500 mg/h, removal efficiencies were 75% for chlorfluazuron and 77% for chlorothalonil; increases of 24% over pump recirculation only. After the ozone treatment, all the pesticide residuals met the Standards for Pesticide Residue Limits in Foods.