臭氧氧化降解水中青霉素G特性和动力学特征

Degradation Characteristics and Kinetics of Penicillin G in Water by Ozone Oxidation

为考察水中PCN(青霉素G)在臭氧氧化过程中的降解规律与特征,采用臭氧直接氧化法处理模拟废水中的PCN,研究了初始pH、ρ(臭氧)、初始ρ(PCN)、自由基抑制剂TBA(叔丁醇)、反应温度等对水中PCN去除效果的影响,并分析了PCN在臭氧氧化降解过程中的降解特性和动力学特征.结果表明:①在溶液体积为1 L、初始ρ(PCN)为50 mg/L、初始pH为11、ρ(臭氧)为15 mg/L、反应温度为20℃时,反应5 min时PCN去除率为100%,反应2 h时TOC去除率为28.98%.②PCN的降解速率和TOC去除效果随pH的增大而升高,碱性环境有利于PCN的矿化.③臭氧氧化过程中,PCN的降解以臭氧直接氧化为主,其降解中间产物的矿化主要以臭氧间接氧化为主,TBA可抑制强氧化性羟基自由基的产生效率,因而对TOC的矿化有明显的抑制作用.④对PCN的降解过程进行一级、伪一级和二级动力学方程拟合,结果表明,伪一级动力学方程拟合相关性(R^2=0.999 7)最高,k(反应速率常数)最大值为0.825 5 min-1.研究显示,臭氧直接氧化可有效降解水中PCN,但对中间产物的矿化去除效果较为有限,臭氧氧化降解PCN的过程遵循伪一级反应动力学方程.

In order to investigate the degradation characteristics of PCN(Penicillin G)by ozone oxidation,the PCN in simulated wastewater was treated by direct ozone oxidation.The effects of initial pH,ρ(ozone),ρ(PCN),radical scavenger TBA(t-butanol)and temperature etc.on the removal of PCN in water were investigated,and the degradation characteristics and kinetics of PCN were analyzed.The results showed that:(1)When the solution volume was 1 L,the initialρ(PCN)was 50 mg/L,the initial pH was 11,theρ(ozone)was 15 mg/L,and the reaction temperature was 20℃,the PCN removal could reach 100%after 5 min of reaction,and the TOC removal was 28.89%at 2 h.(2)The degradation of PCN and TOC removal efficiency increased with the increase of initial pH,and the alkaline environment was beneficial to the mineralization of PCN.(3)During the process of ozone oxidation,the degradation of PCN was mainly caused by direct ozone oxidation,while the mineralization of PCN and its degradation intermediates was mainly dominated by indirect oxidation of free radicals;TBA could inhibit the production efficiency of strong oxidative hydroxyl radicals,thus inhibiting the mineralization of TOC obviously.(4)The first-order,pseudo-first-order and second-order kinetic equations fitted the degradation process of PCN,and it showed that the pseudo-first-order kinetic equation had the highest correlation,R^2=0.9997,and the maximum value of k was 0.8255 min^-1.It showed that direct ozone oxidation could effectively degrade PCN in water,but the mineralization removal of the intermediate products was limited.The ozone oxidative degradation process of PCN followed the pseudo first-order reaction kinetics.