萘和p,p′-DDE在典型包气带介质上的吸附动力学及吸附-解吸特征  

The Sorption Kinetics and Sorption-Desorption Characteristics of Naphthalene and p,p′-DDE in the Typical Media of Vadose Zone

作　　者：马文洁[1] 何江涛[1] 金爱芳[1] 鞠晓明[1] 

机构地区：[1]中国地质大学(北京)水资源与环境工程北京市重点实验室,北京100083

出　　处：《农业环境科学学报》2010年第7期1275-1282,共8页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(40702060);国家高技术研究发展计划(863)项目(2006AA100205-3)

摘　　要：选取3种典型包气带土壤为吸附剂,萘和p,p′-DDE为吸附质,研究了其吸附动力学特征及吸附解吸规律。实验结果显示,初始浓度越大,吸附到达平衡所需时间就越短。数据拟合结果表明,单一级次的动力学方程难以描述两种吸附质的吸附动力学特征,分析认为土壤对有机污染物的吸附过程不是单一反应,而是有机污染物在无机矿物、无定型有机碳和凝聚型有机碳上同时进行吸附反应的复合结果。萘与p,p′-DDE的吸附、解吸过程均表现出非线性,Freundlich方程的吸附指数n在不同程度上偏离1;两种污染物在土样中的吸附过程不完全可逆,Kow、初始浓度以及土壤有机碳含量（fo）c的差异都影响其在土壤不同组分上的吸附百分比,进而影响解吸率。萘更多地吸附在无机矿物表面及无定型有机碳上,随着初始浓度的增大（37.7~780.9μg.L-1）,解吸率可从10%左右增至近85%;而当初始浓度为37.7μg.L-1时,随foc的增大（0.01%~0.65%）,解吸率由12.39%降至3.90%。p,p′-DDE则更多地吸附在凝聚型有机碳上,解吸率随浓度的变化（11.0~275.1μg.L-1）仅在1%~5%内波动,当初始浓度为11.0μg.L-1时,解吸率随foc的增大由4.49%降至1.06%。两者解吸率都和foc呈负相关关系。The sorption kinetics and sorption-desorption characteristics of naphthalene and p,p′-DDE in three typical vadose zone soils were studied in the batch experiments.The sorption kinetic data showed that the time to reach equilibrium decreased with increasing initial con-centrations.The sorption kinetics of naphthalene and p,p′-DDE could not be properly fitted by any orde（r5）kinetic equation,which indicat-ed that there were several processes involved in the sorption.The non-linear sorption-desorption processes of naphthalene and p,p′-DDE could be described by the Freundlich model and their sorption processes were not fully reversible.Due to the difference in hydrophobicity,the sorbed proportions of naphthalene and p,p′-DDE to inorganic minerals,condensed and amorphous organic carbon in soils were different.Con-sequently,the desorption rate varied.Naphthalene molecules were mainly adsorbed on the surface of inorganic minerals and amorphous organ-ic carbon,and its desorption rate increased from 10% to 85% with initial concentrations increased from 37.7 to 780.9 μg.L-1.At the initial concentration of 37.7 μg.L-1,with increase soil organic carbon content from 0.01% to 0.65%,the desorption rate of naphthalene decreased from 12.39% to 3.90%.However,the p,p′-DDE molecules were mainly adsorbed to the condensed organic carbon,and its desorption rate was almost constan（tvaried in a range from 1% to 5%）with the change of initial concentrations from 11.0 to 275.1 μg.L-1.With increase of soil or-ganic carbon content from 0.01% to 0.65%,the desorption rate of p,p′-DDE decreased from 4.49% to 1.06% when initial concentration was 11.0 μg.L-1.Desorption rates of naphthalene and p,p′-DDE were both negatively correlated with the organic carbon content of soils.

关 键 词：萘 p p′-DDE 吸附 解吸 土壤 包气带 

分 类 号：X131.3[环境科学与工程—环境科学]