湿式催化氧化法处理高浓度高盐毒死蜱废水

Treatment of high-concentration and high-salt chlorpyrifos wastewater by catalytic wet air oxidation

以γ-Al_(2)O_(3)为载体,通过超声浸渍法制备了Mn-Ce/γ-Al_(2)O_(3),以其为催化剂采用湿式催化氧化法处理高浓度高盐毒死蜱废水。通过FTIR、XRD、SEM对催化剂进行了表征。通过单因素实验探讨了反应温度、pH、催化剂用量、氧化剂用量对化学需氧量(COD)去除率的影响。采用均匀设计法对湿式催化氧化实验条件进行了优化,在进水COD质量浓度为13550mg/L时,最优处理条件为反应温度230℃,反应时间2h,进水pH=7,质量分数30%过氧化氢5.5mL,Mn-Ce/γ-Al_(2)O_(3)用量0.4g。在该条件下,COD去除率达到90.63%;各因素影响结果的主次顺序为:反应温度>催化剂用量>氧化剂用量>pH>反应时间。采用密度泛函理论(DFT)方法计算了毒死蜱分子的量子化学参数,初步探讨了湿式催化氧化降解毒死蜱的可能机理。结果表明,γ-Al_(2)O_(3)上负载了MnO_(2)、CeO_(2)活性组分,Mn-Ce/γ-Al_(2)O_(3)能较好地促进H_(2)O_(2)产生·OH。湿式催化氧化对废水COD的降解过程符合准二级动力学方程。

Mn-Ce/γ-Al_(2)O_(3) was prepared by ultrasonic impregnation method usingγ-Al_(2)O_(3) as carrier and was used as catalyst to treat chlorpyrifos wastewater with high concentration and high salt by catalytic wet air oxidation.The catalyst was characterized by FTIR,XRD and SEM.By single factor experiment,the effects of reaction temperature,pH,catalyst dosage and oxidant dosage on chemical oxygen demand(COD)removal rate were investigated.Uniform design method was used to optimize the experimental conditions of catalytic wet air oxidation.When the mass concentration of influent COD was 13550 mg/L,the optimal conditions of catalytic wet air oxidation were as follows:reaction temperature of 230℃,reaction time of 2h,influent pH of 7,30%mass fraction hydrogen peroxide of 5.5 mL,Mn-Ce/γ-Al_(2)O_(3) catalyst dosage of 0.4g.Under these conditions,COD removal rate reached 90.63%.The primary and secondary order of various factors affecting the results was reaction temperature>amount of catalyst>amount of oxidant>pH>reaction time.Quantum chemical parameters of chlorpyrifos molecule were calculated by density functional theory method(DFT).Possible mechanism of catalytic wet air oxidation degradation of chlorpyrifos was preliminarily discussed.The results showed that active components MnO_(2) and Ce O_(2) were loaded onγ-Al_(2)O_(3).Mn-Ce/γ-Al_(2)O_(3) could better promote H_(2)O_(2) to produce·OH.The degradation process of wastewater COD by catalystic wet air oxidation was in line with the quasi-second-order kinetic equation.