CTAB改性地聚合物同时去除Cu(II)和Cr(VI)

地聚合物（Geopolymer，简称GP）是由含硅铝酸盐的偏高岭土（Metakaolin，简称MK）或固体废料（如粉煤灰）经碱性激活制备的立体网状结构无机聚合物，对大部分重金属阳离子有良好的吸附作用，但对以阴离子形态存在的重金属吸附效果很差.本研究以偏高岭土为主要原料制备GP，同时用CTAB进行改性，研究其化学组成变化及对典型以阴、阳离子形态存在的重金属Cr（VI）和Cu（II）的同时吸附作用.结果表明，pH为5、吸附时间为24 h、初始浓度为50 mg·L^-1、吸附剂投加量为1 g·L^-1时，CTAB-GP对Cu（II）的去除率达到98.6%，Cr（VI）的最高去除率为25.6%，同时还发现溶液中Cu（II）的存在对吸附Cr（VI）有较大促进作用.整体来看，两种金属混合吸附时很好地符合二级动力学规律，单溶质吸附很好地符合Langmuir和Freundlich等温式，Cu（II）和Cr（VI）的理论最大吸附量分别为147.1 mg·g^-1和63.1 mg·g^-1.XRD、FTIR和BET表征分析结果表明，CTAB-GP中即使存在季铵盐阳离子，但依然属于地聚合物.CTAB-GP可以不牺牲对重金属阳离子吸附性能的同时吸附阴离子，优于常规地聚合物，鉴于CTAB-GP的这种特性，其在重金属污染防治中显示出极大的应用前景.

Simultaneous removal of Cu(II) and Cr(VI) with CTAB modified geopolymer

Geopolymer (GP) is a three-dimensional network structure inorganic polymer prepared by alkaline activation of solid waste materials containing metakaolin or solid waste (such as fly ash), and it exhibits excellent adsorption capacity for most of heavy metal cations, but it exhibits almost no effect on the adsorption of heavy metal anions. In this study, cetyltrimethylammonium bromide (CTAB) modified GP was prepared by using metakaolin as the raw material, and its chemical composition and adsorption performance for the removal of typical heavy metals ions were investigated. The results show that the maximum removal efficiency of 98.6% and 25.6% were achieved for Cu(II) and Cr(VI), respectively at pH 5, adsorption time 24 h, initial concentration 50 mg·L^-1 and adsorbent dosage 1 g·L^-1. It was found that the adsorption of Cr(VI) by the CTAB modified GP (CTAB-GP) was enhanced by the presence of Cu(II) in aqueous solution. Overall, the adsorption process fitted well to the second-order-kinetics in the presence of the two kinds of heavy metals simultaneously, while the adsorption kinetics was well fitted by the Langmuir and Freundlich isotherms in the presence of each of the heavy metals alone, and the theoretical maximum adsorption capacities of Cu(II) and Cr(VI) are 147.1 mg·g^-1 and 63.1 mg·g^-1, respectively. XRD, FTIR and BET analysis results clearly demonstrate the presence of quaternary ammonium cations on the surface of CTAB-GP which is still classified to be the geopolymer. CTAB-GP is superior to conventional GP because it can adsorb anionic heavy metals without sacrificing the capacity in adsorption of cationic heavy metals and shows great application potential for remediation of heavy metal-contaminated water.