活性氧降解水中乐果效率及机理分析

Degradation Efficiency and Mechanism Analysis of Dimethoate in Water by Active Oxygen

近年来农药厂搬迁后残留厂区土壤及水体中有机磷农药污染已经成为广泛关注的环境问题,有机磷农药在水体中的毒性持久性、中间产物高毒性等对环境生态和人体健康造成危害。该文采用实验室臭氧高级氧化技术降解水中乐果,由于臭氧在水中与部分有机物等形成多种自由基,该方法降解效率高、无二次污染风险,是绿色高效的降解方式。结果表明,臭氧通入纯水中,可以产生各种自由基等活性氧,通气20 min内可以降解水中近89.72%的乐果,但是过长时间的通气,臭氧降解并不能达到更高的降解率。在乐果污染程度越低的水体中,短时间的臭氧处理即可达到较高的降解效率。根据试验结果推测,臭氧产生的活性氧等对水中乐果的降解过程主要分为4种,包括P=S键的断裂、P-S键的断裂、S-C键的断裂和C-N键的断裂,形成相应的中间产物,再进一步氧化成相应的氧化物,C原子彻底氧化成CO。可以将活性氧用于进一步降解土壤地下水中有机磷农药的降解和污染治理。

Recently with the movement and migration of pesticide factories,the pollution of organophosphorus pesticides in soil and water has attracted a widespread concern.The persistence of organophosphorus pesticides in water and the high toxicity of intermediate products has caused ecological,environmental and human risks.This paper used ozone advanced oxidation technology to degrade dimethoate in water in a lab study.This method has high degradation efficiency and little risk of secondary pollution,green and efficiently degrading.The results showed that aerating ozone into water can produce sorts of free radicals activite oxygen.Ozonization degraded nearly 89.72%of dimethoate in water within 20 minutes,while a higher degradation rate cannot be achieved by the degradation of too long ozone aeration.In a water body with a lower concentration of dimethoate pollution,a short time ozonization treatment reached a higher degradation efficiency.It was speculated from the investigation that The degradation process of dimethoate by ozone in water was mainly divided into three types,including P=S bond and P-S bond breakage,S-C bond breakage and C-N bond breakage,to form responding intermediates and subsequently to produce responding oxidizes.The method could be used in the control and degradation of organophosphous pesticides in soil and groundwater in the future.