改性ZSM-5介孔沸石分子筛对焦化尾水吸附行为及动力学

Adsorption behavior and kinetics for coking biological treated effluent by modified ZSM-5 mesopores zeolite molecular sieve

通过改性制备了具有二次介孔的沸石分子筛（ZSM-5m）,使用SEM、N2吸附-脱附等温线和XRD对材料的结构进行了表征。以焦化尾水残余有机污染物（ROPs）为研究对象,探讨ZSM-5m对ROPs的吸附行为和动力学。结果表明,溶液初始p H和吸附剂投加量对吸附效率均有一定的影响,ZSM-5m吸附量明显高于ZSM-5。在初始COD为150~350 mg/L,p H为3.0,投加量为2.0 g/L,吸附300 min后,ZSM-5m对COD去除率达到57.5%~69.7%,吸附量达到14.9~25.1 mg/g。吸附动力学拟合结果显示,可以更好地用假二级动力学方程和Elovich模型来描述;动边界模型推算表明,吸附的主要速度控制步骤为颗粒内扩散,温度升高,颗粒扩散控制作用减弱,表观活化能为12.58 k J/mol。推测ZSM-5m对ROPs的吸附是非均相扩散为主,带有复杂转化的物理吸附和化学吸附过程。

The zeolite molecular sieves with secondary mesopores（ ZSM-5m） were prepared by the modification of ZSM-5,SEM,N2 adsorption desorption isotherms and XRD were used to characterize them. Taking residual organic pollutants（ ROPs） from coking biological treatment effluent as the research object,the adsorption behaviors and kinetics of ZSM-5mwere investigated. The results show that the initial p H and adsorbent dosage have some influences on the adsorption efficiency. The adsorption capacity of ZSM-5mwas significantly higher than that of ZSM-5. Under the initial COD concentration of 150—350 mg / L,p H of 3. 0,dosage of 2. 0 g / L,adsorption time of 300 min,the percent COD removal and adsorption capacity by ZSM-5mreached 57. 5% —69. 7% and 14. 9—25. 1 mg / g,respectively. The adsorption kinetics of ZSM-5mon ROPs can be better fitted in pseudo second-order equation and Elovich model. The indication of moving boundary model calculation revealed that the main control step of the adsorption is intra-particle diffusion; the particle diffusion control performance weakened with the increasing of temperature,the apparent activation energy is 12. 58 k J / mol. It is suggested that the ROPs adsorption by ZSM-5mis physical and chemical adsorption process with heterogeneous diffusion complex transformation.