吉林省2种典型耕地土壤对邻苯二甲酸二丁酯的吸附特性

Adsorption Characteristics of Dibutyl Phthalate on Two Typical Cultivated Soils in Jilin Province

为了研究邻苯二甲酸酯类化合物在土壤中可能存在的环境风险,参照OECD guideline 106批平衡方法研究白浆土和黑土对邻苯二甲酸二丁酯(DBP)的吸附动力学、热力学以及阳离子强度和pH对吸附的影响。结果表明:DBP在2种土壤中的吸附平衡时间约为24 h,吸附动力学特征符合准二级动力学方程、Elovich方程和粒子扩散方程,说明吸附过程中存在化学吸附并属于非均相扩散过程;吸附热力学特征均符合Freundlich方程,其吸附容量K_(f)均满足白浆土>黑土,说明白浆土对DBP的吸附能力强于黑土,通过吸附自由能(ΔG)表明,2种土壤对DBP的吸附过程是以物理吸附为主的自发反应;其吸附量与温度呈正相关,属于吸热反应;背景电解质溶液中Ca^(2+)浓度的上升会增加DBP在土壤中的吸附量;pH 2~10与DBP在土壤中的吸附量呈负相关。研究表明,不同类型土壤对DBP的吸附能力存在差异,温度、阳离子强度和pH在吸附过程中起到重要作用。

In order to study the possible environmental risk of phthalic acid esters in soil,adsorption kinetics and thermodynamics of dibutyl phthalate(DBP)and the effects of cation intensity and pH on adsorption were studied with reference to OECD guideline 106.The results showed that the adsorption equilibrium time of DBP in two kinds of soil was about 24 h,and the adsorption kinetic characteristics accorded with the pseudo-second-order equation,the Elovich equation and the particle diffusion equation,indicating that there is chemical adsorption in the adsorption process,which belongs to heterogeneous diffusion process.The thermodynamic characteristics of adsorption all conformed to the Freundlich equation,and the adsorption capacity K_(f)all satisfied planosol>black soil,indicating that the adsorption capacity of planosol to DBP is greater than black soil.The free energy for adsorption(ΔG)showed that the adsorption process is a spontaneous reaction based on physical adsorption The amount of adsorption was positively correlated to temperature,which belongs to the endothermic reaction.The increase of Ca^(2+)concentration in the background electrolyte solution increased the adsorption amount of DBP in soil;pH was negatively correlated with the adsorption amount of DBP in soil with the range of 2~10.The research results showed that the adsorption capacity of different types of soil to DBP is different.Temperature,cation strength and pH play important roles in the adsorption process.