准分子灯光照降解水相中烷基酚的动力学

Kinetics of Alkylphenols Degradation in Aqueous Phase with Excilamp Irradiation

准分子灯辐射的206 nm紫外光可以直接光解4-壬基酚(4-NP)和4-辛基酚(4-OP),但不能使之完全氧化为CO2.相同光照条件下,4-OP的去除率高于4-NP.采用拟一级动力学模型和修正的动力学模型对光解过程进行拟合,得到两种烷基酚206 nm直接光解的速率常数.结果表明,烷基酚初始浓度越低,光解速率常数越高.两种动力学模型对低浓度烷基酚直接光解都具有一定的适用性,但修正的模型不适合高浓度4-OP直接光解.UV/H2O2体系中,烷基酚的降解速率明显提高,但只有当H2O2加入量很高时,TOC去除才比较明显.最后,推导出4-OP直接光解的速率常数kd为0.0328 min-1,4-OP与H2O2反应的速率常数kpH为17.4520 L·(mol·min)-1.

The 206 nm irradiation from excilamp was able to directly photo-degrade 4-nonylphenol( 4-NP) and 4-octylphenol( 4-OP),but it could not oxidize them completely into CO2. Under the same irradiation condition,the removal efficiency of 4-OP was higher than that of 4-NP. Pseudo-first order kinetic model and modified kinetic model were used to fit the kinetics of photo-degradation process,and the direct photolysis rate constants under 206 nm UV irradiation were obtained. The experimental results demonstrated that the photolysis rate constant was higher at lower initial concentration of alkylphenols. Two kinetic models were appropriate for the direct photolysis of alkylphenols at low concentration,but the modified model did not fit for high concentrations. Degradation rate can be obviously enhanced when adding H2O2into the reaction,but the TOC removal was distinct only when the dosage of H2O2was high. At last,we concluded that the direct photolysis rate constant kdwas 0. 032 8 min-1and the reaction rate constant kpHbetween 4-OP and H2O2was 17. 452 0 L·( mol·min)-1.