Tween20对DDT在胶州湾沉积物上吸附行为的影响

Influence of Tween20 on sorption behaviors of DDT on sediment from Jiaozhou Bay

研究了非离子表面活性剂失水山梨醇聚氧乙烯(20)醚月桂酸酯(Tween20)对二氯二苯基三氯乙烷(滴滴涕,DDT)在海洋沉积物上吸附动力学和热力学行为的影响.在实验浓度范围内,Tween20的加入能够加快DDT在沉积物上的吸附速率,吸附符合伪二级吸附速率方程,吸附等温线符合Freundlich等温式,吸附作用随着Tween20初始浓度的增加而增强.对吸附影响因素的研究表明,随着体系的离子强度增加,温度降低,沉积物对DDT的吸附能力增加.在281～308K范围内,热力学函数表明,该过程是一个自发的、放热的、熵增加的物理吸附过程,Tween20的存在使DDT在吸附过程中的│ΔGθ│、│ΔHθ│值更大,ΔSθ更小.

The effects of nonionic surfactant Tween20 on the sorption of DDT onto sediment were studied through kinetic and thermodynamic analysis.Tween20 could accelerate the sorption rate of DDT onto sediment and the sorption kinetic curves could be fitted by the pseudo-second-order model well in experimental concentrations.The sorption isotherms were in good agreement with the Freundlich equation.The sorption capacity increased with increasing initial concentrations of Tween20.Studies on impact factors of the sorption indicated that sediment enhanced its capacity to absorb DDT with increasing ionic strength and decreasing temperature in the experimental system.In the temperature range from 283 K to 308 K,thermodynamic parameters showed that the process was a spontaneous,exothermic and entropy-increasing physical one.The existence of Tween20 caused the │ΔGθ│and│ΔHθ│values higher and ΔSθ value smaller during the DDT sorption process.