超声波降解水溶液中对二氯苯

Study on ultrasonic degradation of p-dichlorobenzen in aqueous solutions

采用超声波降解含对二氯苯(p-DCB)的溶液,研究了p-DCB降解的动力学和影响因素。结果表明:(1)超声波降解水溶液中的p-DCB,随着p-DCB初始浓度的增加降解率减小;p-DCB的超声波降解反应符合表观一级动力学规律。(2)增大超声波频率和功率以及双频率联合使用可以增大p-DCB的降解率和一级反应速率常数。(3)弱酸性或中性环境更有利于p-DCB的降解进行。(4)反应时的搅拌和自由基清除剂的投加都降低了p-DCB的降解率,这是因为超声波降解时空化气泡内的热裂解和自由基作用的削弱。(5)在单一体系中,p-DCB比对氯苯胺(p-ClA)更易降解。在混合体系中,p-ClA的加入没有显著降低p-DCB的去除效果,因为亲水的p-ClA不易挥发,难以进入空化气泡竞争能量和自由基,其存在对空化气泡内混合气体的比热容比影响较小;而p-DCB的存在却明显降低了p-ClA的降解效果,因为疏水的p-DCB易挥发进入空化气泡竞争能量和自由基,并降低混合气体的比热容比。

The ultrasonic degradation of p-dichlorobenzen（p-DCB）in aqueous solution was studied,and the effect of influence factors on reaction kinetics was investigated.The results showed that the sonolysis process followed the apparent first order kinetics,and the reaction rate constant decreased with increasing the initial p-DCB concentration.The degradation of p-DCB was promoted by increasing intensity and frequency of ultrasonic,and acidulous or neutral conditions were favorable for the degradation of p-DCB.Stirring and butanol weakened the thermal cracking and decreased ·OH radical content in cavitation bubbles and thus retarded p-DCB degradation.Ultrasonic degradation of p-DCB was easier than that of p-chloroaniline（p-ClA）in single degradation system.In the mixture system of p-DCB and p-ClA,the sonolysis rate of p-DCB was not significantly influenced by p-ClA,because p-ClA was nonvolatile and hydrophilic,and it was difficulity for p-ClA to compete the energy and ·OH radical in cavitation bubbles.While the presence of p-DCB decreased the p-ClA sonolysis rate obviously for hydrophobic p-DCB was easy to enter into cavitation bubbles for energy and ·OH radical competition and then decreased the specific heat of mix gas.