腐殖酸对巯基功能化离子印迹聚合物吸附Cd^(2+)的增效作用  

Enhanced adsorption of Cd^(2+) on ion-imprinted thiol-functionalized polymer by humic acid

作　　者：谢彬彬[1] 廖建波[1] 胡芸[1,2] 吴超飞[1,2] 韦朝海[1,2] 

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]工业聚集区污染控制与生态修复教育部重点实验室,广州510006

出　　处：《环境化学》2017年第6期1213-1225,共13页Environmental Chemistry

基　　金：国家自然科学基金-广东联合基金(U1201234)资助~~

摘　　要：复合污染条件下共存的有机物可能对水溶液中重金属的吸附去除产生抑制作用,作为天然水体中有机物的代表,腐殖酸(Humic acid,HA)对水体中重金属的迁移转化等具有极其重要的影响.采用表面印迹法合成了巯基功能化离子印迹聚合物IIP-MPTS/SiO_2,利用扫描电镜(SEM)、X射线能谱仪(EDS)、傅里叶红外光谱仪(FT-IR)、X射线衍射仪(XRD)等方法对其进行了表征.以HA作为共存有机物,以IIP-MPTS/SiO_2作为吸附剂,研究HA对IIP-MPTS/SiO_2吸附去除水体中Cd^(2+)的影响.HA与Cd^(2+)相互作用的紫外吸收光谱表明,基于Cd^(2+)浓度的HA分子聚合增强作用,增大了分子体系的共轭程度,使紫外光谱吸收峰红移;溶液离子强度的增大也促进紫外光谱吸收带的红移和吸收强度的增大.吸附实验表明,Cd^(2+)在IIP-MPTS/SiO_2上的吸附容量随溶液pH值(2.00—8.00)的升高而逐渐增大;共存HA对Cd^(2+)在IIP-MPTS/SiO_2上的吸附具有增效作用,但降低了吸附反应速率;吸附行为符合拟二级动力学模型,吸附等温线可以用Langmuir模型描述;吸附过程为自发吸热反应,HA的存在增大了吸附反应的自发程度,吸附能垒降低.结合XPS分析结果,推断共存HA促进Cd^(2+)吸附的原因是,HA作为配位体桥梁而形成IIP-MPTS/SiO_2-HA-Cd^(2+)稳定的三元配位化合物,通过富集而促进Cd^(2+)的吸附.Humic acids（HA） present in natural waters play a key role in the migration,transformation and ultimate fate of heavy metals in water for example by inhibiting the adsorption of heavy metals on adsorbents applied in the water treatment. An ion-imprinted thiol-functional silicabased polymer IIP-MPTS/SiO_2 was synthesized using a surface imprinting technique for competitive adsorption of Cd^2＋ from HA-containing aqueous solutions. The adsorbent was characterized by SEM,EDS,FT-IR,and XRD. Experimental study on the adsorption of Cd^2＋ in to presence of HA was also undertaken. The UV-vis adsorption spectra of aqueous solutions containing Cd^2＋ and HA showed enhanced aggregation of HA and an increased number of Cd-conjugated HA molecules withincreasing Cd^2＋ concentration,which resulted in a red shift of the absorption peaks. With increased ionic strength,the absorption bands showed red shift with increased absorption intensity. The results of adsorption experiments showed that the adsorption capacity of IIP-MPTS/SiO_2 for to Cd^2＋ increased with the pH from 2.0 to 8.0. A enhancement effect of HA on the adsorption capacity was observed,although the adsorption rate in presence of HA decreased. The Cd^2＋ adsorption kinetics and isotherms both in the absence and presence of HA fit well to the pseudo-second order and Langmuir models,respectively. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic within the experimental temperature range. The spontaneity of adsorption increased and the sorption barrier decreased when HA was present. Combined with X-ray photoelectron spectroscopy（XPS） analysis,a mechanism of enhanced Cd^2＋ sorption was proposed,in which HA as a ligand bridge simultaneously formed complexes with the surface sites of the IIP-MPTS/SiO_2 and Cd^2＋ , thus binding Cd^2＋ indirectly to the adsorbent and enhancing the adsorption.

关 键 词：复合污染 腐殖酸 离子印迹 吸附 CD^2+ 增效作用 

分 类 号：X52[环境科学与工程—环境工程]