表面活性剂光催化降解动力学研究

为了研究光催化法对不同电荷类型表面活性剂的降解性能,在紫外光照射下,用TiO2光催化剂对阴离子表面活性剂十二烷基磺酸钠(SDS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和两性表面活性剂十八烷基甜菜碱(BS18)进行降解试验.同时,探讨了TiO2光催化剂加入量、表面活性剂初始质量浓度及初始pH对光降解的影响及其动力学过程.结果表明,3种表面活性剂的降解行为符合准一级动力学规律,3种表面活性剂降解速率快慢顺序为:BS18CTABSDS.SDS和BS18的最佳TiO2催化剂用量为1 g.L-1,而CTAB的最优用量为2g.L-1;CTAB和BS18的光降解速率随着活性剂初始质量浓度的增大而线性减小,SDS的降解速率则随活性剂初始质量浓度的增加而缓慢增大;CTAB和BS18在偏碱性条件下降解最快,而SDS在弱酸条件下具有最大的动力学降解速率.

Photocatalytic degradation kinetics of common surfactants over TiO2

The photocatalytic degradation of sodium dodecylsulfate (SDS), cetyltrimethylammonium bromide (CTAB) and octadecyldimethylbetaine (BS18) was studied using TiO2 and UV radiation. The effects of TiO2 dosage, initial concentrations of the surfactants and initial pH on the photodegradation were investigated. The photodegradation profiles of the surfactants at different initial concentrations were fitted with pseudo-first order kinetics equation. The photodegradation rates followed the order BS18>CTAB>SDS. The optimum catalytic dosages were 1 g•L-1, 1 g•L-1, 2 g•L-1 for SDS, BS18 and CTAB, respectively. The initial concentrations of CTAB and BS18 exhibited a significantly negative effects, whereas the initial concentration of SDS showed a slightly positive effect on the photodegradation rate. Alkaline pH was more efficient for the photodegradation of CTAB and BS18, while weak acidic pH for the photodegradation of SDS.