| Herbicide Atrazine?ATZ?is one of the most widely used chemical herbicides at home and abroad.In recent years,its role in endocrine disrupting has attracted the attention of many scholars.ATZ began to be used in China's agricultural production around 1980,however,the problem of unreasonable use of pesticides in agricultural production has become increasingly prominent in recent years in our country,arousing close attention of people from all walks of life.ATZ can migrate and transform between different environmental media such as water,atmosphere and soil.It can enter the water through surface runoff,leaching,dry/wet deposition and other ways.Therefore,finding a safe,reliable,rapid and economical method of degradation of ATZ is imminent.In this study,single factor method was used to investigate the effects of ozone?O3?,ozone/peroxy-monosulfate?O3/PMS?and ozone/hydrogen peroxide?O3/H2O2?advanced oxidation technology on degradation of ATZ under different temperature,pH,etc.The effect is selected,the optimal treatment condition is selected and the mechanism analysis and the vertical dynamic analysis are made to provide a theoretical basis for engineering practice.Now come to the following conclusion:The effect of ozone?O3?degradation on atrazine?ATZ?under different conditions was investigated in phosphate buffer and the degradation mechanism was discussed.The results showed that the degradation rate of ATZ was 92.51%when the reaction temperature was20?,O3 concentration was 60?mol/L and ATZ concentration was 2.5?mol/L in pH7phosphate buffer.The mechanism analysis showed that the pH value had a significant effect on the degradation of ATZ,and the degradation efficiency was much better than that under acidic conditions.Under acidic conditions,O3 degrades ATZ process mainly by direct oxidative degradation.Under alkaline and neutral conditions,O3degraded ATZ process with HO·oxidative degradation,O3 direct oxidation degradation accounted for about 10%.The kinetic analysis of O3 degradation ATZ showed that the ATZ kinetics of O3 degradation was more consistent with the quasi-second-order reaction kinetics under different temperature,pH value and O3 concentration.The degradation of atrazine?ATZ?by ozone/peroxy-monosulfate?O3/PMS?under different conditions was investigated in phosphate buffer and the degradation mechanism was discussed.The results showed that 2.5?mol/L ATZ could be completely degraded in O3/PMS system for 5min when the reaction temperature was 20?,the concentration of PMS was 10?mol/L and the concentration of O3 was 20?mol/L in pH8 phosphate buffer.The mechanism analysis showed that phosphate is a high quality buffer during O3/PMS degradation ATZ,the phosphate has the excitation effect to the PMS and the acidic condition is better than the alkaline condition.both under acidic and alkaline condition,O3/PMS degradation of ATZ process are free radical oxidation degradation,O3 direct oxidation degradation accounted for about 6-7%.Specific performance as,SO4-·oxidation degradation is dominated in the acidic condition,HO·and SO4-·are co-oxidized degradation and HO·oxidation degradation is the main way under neutral conditions,HO·and SO4-·are co-oxidized degradation and the HO·and SO4-·oxidation degradation ratios are close to 1:1under alkaline conditions.The kinetic analysis of O3/PMS degradation ATZ showed that the ATZ kinetics of O3/PMS degradation was more consistent with quasi-second-order reaction kinetics under different temperature,pH value and PMS concentration.The effect of ozone/hydrogen peroxide?O3/H2O2?degradation on atrazine?ATZ?under different conditions was investigated in phosphate buffer and the degradation mechanism was discussed.The results showed that the degradation rate of ATZ was 89%and after which the ATZ concentration tends to be stable when the reaction temperature was 20?,O3 concentration was 20?mol/L,H2O2 concentration was 20?mol/L and ATZ concentration was 5?mol/L in pH8 phosphate buffer.The mechanism analysis shows that the addition of H2O2 in O3/H2O2 system can significantly accelerate the chain decomposition of O3 to produce a large amount of HO·.The higher the temperature,the higher the pH value,the better effect of O3/H2O2 degradation on ATZ,the H2O2 concentration from low to high the degradation rate of ATZ was increased first and then decreased by O3/H2O2,the best reaction mole ratio of O3 and H2O2 was 1:2.pH value has a significant effect on O3/H2O2degradation ATZ,and the degradation efficiency is better than acidic condition under alkaline condition.Under the acidic condition,O3/H2O2 degrades O3 direct oxidation degradation and HO·oxidation degradation in the process of ATZ degradation close to 1:1.Under the condition of alkaline and neutral,O3/H2O2 degraded ATZ process dominated by HO·oxidation degradation.The kinetics of degradation of ATZ by O3/H2O2 showed that the ATZ kinetics of O3/H2O2 degradation was more consistent with quasi-second-order reaction kinetics under different temperature,pH value and H2O2 concentration. |
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