凹土对酞酸酯在土壤中吸附解吸的影响

摘要

酞酸酯( Phthalic acid esters, PAEs)是水体、农田土壤等环境介质中广泛存在的一类有机污染物。利用批平衡吸附法和连续解吸法研究邻苯二甲酸正丁酯(Dibutyl phthalate,DBP)和邻苯二甲酸(2-乙基)己基酯[Di-(2-ethylhexyl) phthalate, DEHP]在不同凹土含量土壤中的吸附-解吸行为。结果表明,用Freundlich方程与Langumir方程均能较好地拟合DBP和DEHP在不同凹土含量土壤中的吸附行为,其R2均大于0.92。在Freundl-ich模型中DBP和DEHP在凹土含量1.0%、5.0%、10.0%的3种土壤中lgKf值分别为1.5103、1.4050、1.2166和3.1704、3.0848、3.0340。在Langumir模型中Qm值变化与lgKf值变化的趋势相同,同时非线性逐步减弱,说明凹土的加入降低了土壤对DBP和DEHP的吸附强度与吸附容量。 DBP和DEHP在不同凹土含量3种土壤中的lgKoc值与其在Freundlich模型中的lgKf值之间有较强的正相关关系。此外,随着凹土含量的增加,DBP和DE-HP在土壤中的解吸过程加快。%As a group of organic pollutants, phthalic acid esters have been ubiquitous in environmental media for ex-ample water, soil, etc. The sorption and desorption behaviors of dibutyl phthalate ( DBP) and diethylhexyl phthalate( DEHP) on soil with different content attapulgite were studied by batch sorption equilibrium experiments and continuous desorption ex-periments. The results showed that the sorption data of DBP and DEHP in three tested soils were well fitted with Freundlich and Langumir models (R2> 0. 92). In Freundlich model, lgKf values of DBP were 1. 510 3, 1. 405 0 and 1. 216 6 in soils with 1. 0%, 5. 0% and 10. 0% attapulgite, respectively. In same way, lgKf values of DEHP were 3. 170 4, 3. 084 8, 3. 034 0 in corresponding soils. In Langumir model, Qm values of DBP and DEHP also decreased with the increase of at-tapulgite dosages in soils. Those indicated that the adsorption intensity and capacity of soils for DBP and DEHP decreased. And the nonlinear sorption of soils for both compounds weakened with the increase of attapulgite dosages in soils. The lgKoc values showed good correlation with the corresponding lgKf values of DBP and DEHP in Freundlich models. In addition, desorption processes were accelerated and desorption capacities of soils for DBP and DEHP increased with the dosages of attapulgite increas-ing in soils.