Efficacy evaluation of low-concentration of ozonated water in removal of residual diazinon, parathion, methyl-parathion and cypermethrin on vegetable
2007
Wu, J.G. | Luan, T.G. | Lan, C.Y. | Lo, W.H. | Chan, G.Y.S.
The present study investigated the degradation of four pesticides by low-concentration of dissolved ozone in order to establish the effect of operational parameters. The results indicated that dissolved ozone (initial concentration of 1.4 mg/l) was effective to oxidize 60-99% of 0.1 mg/l aqueous diazinon, parathion, methyl-parathion and cypermethrin shortly within 30 min. The feasibilities of applying low dissolved levels of ozone in water (1.4-2.0 mg/l) to remove the target pesticides residing on vegetable surface (Brassica rapa) were studied. Ozonated water was mostly effective in cypermethrin removal (>60%). The efficacy highly depended on the dissolved ozone levels. Higher temperature enhanced the efficacy in pesticide removal; however, the solubility of ozone in water is inversely proportional to temperature. The maximal efficacy for diazinon removal was detected to be at 15-20 °C. Major limitation factors for residual pesticide removal are temperature, concentration of ozone gas applied and concentration of dissolved ozone established.
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