CPDB单一柱撑蒙脱石与CPDB/Al复合柱撑蒙脱石对水中Cr(Ⅵ)的吸附研究

Adsorption of chromium (Ⅵ) ion on montmorillonite modified with hydroxyaluminum and cetylpyridinium bromide

采用聚合羟基铝提供Al源结合十六烷基溴化吡啶(CPDB)改性钠基蒙脱石(MONT),制备了CPDB-MONT和Al-CPDB-MONT吸附剂,利用XRD,BET,FT-IR对样品进行表征,并考察了其对Cr(Ⅵ)的吸附,研究了改性蒙脱石吸附Cr(Ⅵ)的吸附动力学和吸附等温线。经改性后,CPDB与羟基铝均成功柱撑进入MONT层间。相比于MONT,CPDB-MONT与Al-CPDB-MONT分别使层间距从1. 111 8nm扩撑到1. 898 7nm,1. 935 4nm;比表面积分别从46. 249m^2/g增大到136. 111 m^2/g,151. 497m^2/g;经过CPDB改性土和CPDB-Al复合改性土吸附模拟Cr(Ⅵ)废水满足拟二级动力学和Langmuir方程,该过程推动力和吸附类型分别为正负静电引力和物理吸附。相同条件下,Al-CPDB-MONT去除效果优于CPDB-MONT和MONT。在酸性、低温条件下反应效果更佳。

The calcium/montmorillonite was used as raw material,the CPDB-MONT and Al-CPDB-MONT were modified with cetylpyridinium bromide(CPDB)and polymeric hydroxyl aluminum cations.The adsorbents were characterized by XRD,BET,and FT-IR.The adsorption of chromium(Ⅵ)and the adsorption kinetics and isotherms were studied.The aluminum hydroxypolycation and CPDB was intercalated into MONT’s layer successfully by modification.Compared with MONT,CPDB-MONT and Al-CPDB-MONT′s interlayer spacing respectively increased from 1.111 8nm to 1.898 7nm,1.935 4nm;and the specific surface area increased from 46.249m 2/g to 136.111m 2/g,151.497m 2/g,respectively.The results showed that the adsorption process of Cr(Ⅵ)onto CPDB-MONT and Al-CPDB-MONT adsorbents can be described by pseudo-second-order kinetics model;the Langmuir model can preferably describe the adsorption process of Cr(Ⅵ)adsorbed on the two series adsorbents.Both two adsorption belongs to physical adsorption and the main driver of adsorption was the attraction between the positive and negative charges.On the same condition,the maximum adsorption capacity followed the order Al-CPDB-MONT >CPDB-MONT >MONT.