Mg-Al型水滑石对水溶液中F^-的吸附

ADSORPTION OF FLUORIDE FROM AQUEOUS SOLUTION BY Mg-Al HYDROTALCITE

采用水热法合成Mg-A l型水滑石(LDHs),研究LDHs及其焙烧产物C-LDHs对水溶液中F-的吸附行为,并用X射线衍射和热重分析对LDHs,C-LDHs以及吸附F-后的C-LDHs(R-LDHs)的结构和性质进行了表征.结果表明:LDHs对水溶液中的F-基本没有吸附,而C-LDHs对F-有较大的吸附容量,同时,酸性的增强有利于C-LDHs对F-的吸附.C-LDHs对F-吸附4h后可达到吸附平衡.通过吸附F-,C-LDHs的结构由吸附前的混合氧化物固溶体恢复到层状结构,表明C-LDHs对水溶液中F-的高吸附性能是因为其具有较强的“记忆效应”.

In this study, Mg-AI hydrotalcites （LDHs） were prepared by hydrothermal method and the adsorption of fluoride onto the LDHs and its calcined product （C-LDHs） was investigated. XRD and TG were used to characterize the LDHs , C-LDHs and fluoride adsorbed C-LDHs （R-LDHs）. Results show that fluoride adsorption onto the LDHs is negligible, while good sorption of fluoride onto the C-LDH is achieved. The fluoride uptake onto the C-LDHs was further enhanced under acidic solution. The study of adsorption kinetics indicated that the adsorption equilibrium of fluoride onto the C-LDH was achieved in 4h. In addition, the structure of C- LDHs shifted to layer structure of LDHs after the fluoride adsorption, indicating that the memory effect of C - LDHs accounted for the effective removal of aqueous fluoride.