改性粘土矿物的制备及其对水体中二氯喹啉酸的吸附研究

Preparation of modified clay and its adsorptive characteristics towards quinclorac from water

采用固-液吸附法,以天然钙基蒙脱石为原料,硫酸和十六烷基三甲基溴化铵(HDTMAB)为改性剂,制备了3种改性蒙脱石,并借助X-射线衍射、比表面积全分析及有机碳含量测定对所得的改性蒙脱石进行表征.结果表明,先酸化后再进行有机改性所得的改性蒙脱石(AHM)不仅具有较大的比表面积、层间距,而且有机碳含量是最高的.同时,采用批量平衡实验比较了这3种改性蒙脱石和天然蒙脱石对二氯喹啉酸的吸附能力.结果表明,天然蒙脱石对二氯喹啉酸的吸附率最小,不足5%,而先酸化再进行HDTMAB改性所得的改性蒙脱石对二氯喹啉酸的吸附率最高,其对二氯喹啉酸的吸附容量约为天然蒙脱石的20倍.二氯喹啉酸在这种改性蒙脱石上吸附速率很快,吸附平衡时间为2 h,吸附动力学满足准二级动力学方程,吸附等温线可用Linear和Freundlich模型较好地拟合.

Three types of modified clays were produced from nature Ca-montmorillonite using sulfuric acid and hexadecyltrimethyl ammonium bromide( HDTMAB) as surface modifier agents by a solid-liquid adsorption method.Adsorbents were characterized using X-ray diffraction( XRD) and surface area analysis( BET) and organic carbon content analysis.The results showed that the modified montmorillonite( AHM) treated with sulfuric acid and HDTMAB exhibited higher basing,bigger specific surface area and highest organic carbon content. The adsorptive characteristics of these modified and natural montmorillonites towards quinclorac were also studied by batch equilibrium experiments.The results showed that the natural montmorillonite had the lowest adsorption capacity towards quinclorac with a removal efficiency of less than 5%. However,the montmorillonite modified with sulfuric acid and HDTMAB together had the highest adsorption capacity towards quinclorac,and its adsorption efficiency was about 20 times greater than the natural montmorillonite.Quinclorac adsorption onto it was fast and reached equilibrium within 2 hours. The adsorption process was found meet the pseudo second-order kinetic equation,and the adsorption isotherm of quinclorac by modified montmorillonite was well fit with both Linear model and Freundlich model.