Study On Degradation Mechanism Of Organophosphorus Pesticides In Fruits And Vegetables By Electrolyzed Water

Organophosphorus pesticides residues have aroused wide attention of domestic and foreign scientists. The degradation technology of pesticides applied on fruits and vegetables are limited, and there exists many defects which make the application more difficult. This study was carried out with typical organophosphorus pesticides (dimethoate, dichlorvos, chlorpyrifos, parathion and methyl parathion) and chives which have a higher detection rate of pesticide residues as materials, exploring the impact factors and mechanism of eliminating organophosphorus pesticides residual in fruits and vegetables with electrolyzed water (EW). The main findings are as follows:The effect of operating conditions (concentration of hydrochloric acid, sodium chloride concentration, electrolysis voltage, electrolysis current, electrolysis time and the electrode plate distance) of laboratory-made non-barrier type electrolyzed water generator on the pH value and available chlorine concentration(ACC) of EW was investigated. And the rules of preparing EW condition were summarized.The capacity to produce hydroxyl radicals of EW and sodium hypochlorite solution with same physical and chemical indicators, as well as the EW in different storage times were researched, the results showed that in different range of pH and ACC, the capacity to produce hydroxyl radicals of EW were stronger than sodium hypochlorite solution. ACC and pH have a combined effects on the ability to produce hydroxyl radical. EW obtained the maximum hydroxyl radicals when storage time was 5 h.The sensitivity and degradation products of the individual components of chlorpyrifos, parathion, methyl parathion and dimethoate standards were respectively investigated with different EW. When ACC is greater than 5 mg/L, the degradation rates of parathion, dimethoate, chlorpyrifos and methyl parathion reached 100%,100%,99.96%, 99.86%within 30 s respectively. The degradation products and degradation pathways of chlorpyrifos, parathion, dimethoate and methyl parathion were analyzed.EW can effectively remove the dichlorvos, dimethoate and chlorpyrifos residues in leeks, degradation rates reached 98.79%,51.70% and 72.55%, respectively, which were better than that after treatment with NaCIO solution. High ACC enhanced the ability to remove the pesticide residues. At the range of 20-30℃, EW temperature had little effect on the removal of pesticide residues.15:500(g:mL) is the optimum condition of material and EW. The different removal rate of dimethoate and chlorpyrifos using EW illustrated that the ability to remove organophosphorus pesticides residues had a relationship with hydroxyl radicals...