N-LED3A在土壤中的吸附特征及其影响因素

摘要

采用批平衡试验法,研究了新型螯合型表面活性剂N-十二酰基乙二胺三乙酸钠(N-LED3A)在土壤上的吸附特征,并探讨了pH值、温度、离子强度和水土比对N-LED3A在土壤上的吸附影响.结果表明:准二级动力学方程适合描述N-LED3A在土壤上的吸附过程.Langmuir、Freundlich和Dubinin-Radushkevich(D-R)吸附等温方程均可较好地用于拟合吸附行为.土壤有机质和粘土矿物对N LED3A在土壤上的吸附起到重要作用.溶液pH值对N-LED3A在土壤上的吸附有显著影响,随pH值增大(5～11),N-LED3A在土壤上的吸附量明显减小.N-LED3A浓度低于1000mg/L时,升高温度(25,35,45℃)对吸附量影响不大,但当浓度大于3000mg/L时,吸附量随温度的升高有所降低.N-LED3A在土壤上的吸附量随离子强度增大而增加.N-LED3A吸附量随水土比变化顺序为:水/土(20:1)＜水/土(40:1)＜水/土(80:1).%The characteristics of adsorptive thermodynamics and kinetics of a new type chelating surfactant named N-lauroylethylenediaminetetriacetate (N-LED3A) on water/soil interface were studied by the batch equilibration method.The effects of pH value,temperature,ionic strength and water-soil ratio on the adsorption behavior of N-LED3A were also investigated.The results showed that pseudo-second order kinetics equation was adapted to describe the adsorption process of N-LED3A on soil,and Langmuir,Freundlich and Dubinin-Radushkevich (D-R) isotherm models fitted well to the adsorption behavior.In addition,soil organics and clay minerals played important roles in the adsorption characteristics of N-LED3A on soil.The pH values of solution greatly impacted the adsorption process of N-LED3A on soil as well.As the pH value increased from 5 to 11,the adsorption amount of N-LED3A on soil decreased sharply.Moreover,increasing temperature (from 25℃C to 35℃C,and then to 45℃C) had little influence on the adsorption amount when N-LED3A concentration was below 1000mg/L.When N-LED3A concentration was higher than 3000mg/L,however,the adsorption amount decreased as the temperature increased.Besides,the adsorption amount of N-LED3A on soil increased with the increasing Na+ ionic strength in solution,and the adsorption amount varied with water-soil ratio in the sequence of (20∶1)＜(40∶1)＜(80∶1).