臭氧降解水中邻苯二甲酸二甲酯的效能及动力学

Degradation efficiency and kinetics of dimethyl phthalate in aqueous solution by ozonation

利用臭氧降解含较高浓度邻苯二甲酸二甲酯(DMP)的模拟废水,考察了pH、DMP初始浓度、臭氧投加量和温度对臭氧降解DMP效果的影响,并对臭氧降解DMP的效能及动力学进行了研究。结果表明,pH为5～10时DMP的降解效果较好;DMP初始浓度越大,DMP降解率越小,但DMP降解量增加;臭氧投加量的增加有利于DMP降解,但臭氧利用效率降低;温度低时,升高温度DMP降解率增大,24℃后提高温度对DMP降解率影响不大。在pH为5～10、DMP初始浓度为14～66mg.L-1、O3投加量为14～24mg.min-1、20～30℃条件下反应40min,DMP降解率达85%以上。在实验条件范围内,臭氧降解DMP符合拟一级动力学,建立了幂指数表达的动力学模型。在pH为2～12范围内,因臭氧反应机理不同,表观动力学常数kobs与pH不呈线性关系,pH为2～5时,kobs快速增加,pH为5～9时,kobs缓慢增加,pH大于9时kobs反而降低,pH为9时kobs最大,为0.0929min-1。

Ozone was employed for degradation of dimethyl phthalate（DMP）in a simulated wastewater,and the effects of pH,DMP initial concentration,ozone dosage and reaction temperature on DMP degradation and its kinetics were investigated.The experimental results showed that the degradation efficiency of DMP was better in the range of pH 5—10,decreased with increase of DMP initial concentration although degradation total amount of DMP increased gradually,and increased with increase of ozone dosage but ozone utilization efficiency decreased.The reaction temperature had no remarkable effect on the degradation efficiency over 24℃,although below this temperature it increased with rise of temperature.The degradation efficiency could reach up to 85% at the conditions of pH 5—10,DMP concentration 14—66 mg·L-1,ozone dosage 14—24 mg·min-1,temperature 20—30℃ and time 40 min.The degradation of DMP by ozonation followed pseudo-first-order kinetics under the experimental conditions,and its kinetic model was determined.There was no correlation between kobs and pH in the range of pH 2—12,because of different reaction mechanism of ozonation degradation.The kobs increased quickly in pH 2—5 and slightly in pH 5—9,but the decrease of kobs was observed over pH 9,and the biggest kobs was 0.0929 min-1.