臭氧/沸石工艺处理水中硝基苯的效能研究

在连续反应器中,考察了臭氧/沸石工艺在不同条件下去除硝基苯的效果.结果表明,臭氧/沸石工艺对硝基苯的去除效率明显高于单纯臭氧氧化,反应7 min后,硝基苯去除率达到100％,并且该反应符合假一级反应动力学.叔丁醇能抑制臭氧/沸石工艺对硝基苯的去除效率,表明在氧化去除硝基苯过程中羟基自由基起主导作用.增加沸石投量和臭氧浓度均能有效地提高臭氧/沸石工艺对硝基苯的去除效率,并且臭氧/沸石工艺对硝基苯的去除速率与沸石投量之间存在1个最优值,与臭氧浓度呈线性关系.臭氧/沸石工艺对硝基苯的去除速率与初始硝基苯浓度无关.离子强度对臭氧/沸石工艺降解硝基苯的效率影响较大,当离子强度从0增加到1×10^-3　mol/L时,臭氧/沸石工艺对硝基苯的去除率从81.2％降低至31.6％.pH值主要影响臭氧的分解能力,随着溶液pH降低,臭氧/沸石工艺对硝基苯的去除效率逐渐下降.沸石具有较长的使用寿命.

Efficiency Study on Nitrobenzene Removal by Ozone/Zeolite Process

Degradation of nitrobenzene by ozone/zeolite process was investigated in a continuous flow reactor. The results showed that nitrobenzene was degraded by ozone/zeolite process efficiently in comparison to ozone alone. The removal of nitrobenzene was 100% in 7 minutes. The reaction followed pseudo-first-order kinetics. By investigating the effect of scavenger on nitrobenzene removal, it is concluded that nitrobenzene was mainly degraded by hydroxyl radicals in solution. Increasing zeolite dosage and ozone concentration also enhanced nitrobenzene removal. However, there was an optimum removal rate among zeolite dosages. The relationship between the ozone concentrations and the kinetic constants was linear. At the same time, nitrobenzene decomposition was independent of influent nitrobenzene concentration during ozone/zeolite process. Additionally, the degradation rate of ozone/zeolite process was inhibited significantly by increasing ionic strength. When the ionic strength concentration increased from 0 to 1 x 10(-3) mol/L, the removal of nitrobenzene by ozone/zeolite process decreased from 81.2% to 31.6% correspondingly. pH mainly affected the decomposition rate of ozone. As pH decreased, the degradation rate of nitrobenzene by ozone/zeolite process decreased too. Zeolite had a relatively longer lifetime.