Fe/Al改性膨润土对铬酸根的吸附性能研究  

Study on the adsorption of CrO_4^(2-) on Fe/Al modified bentonites

作　　者：吴建军[1,2] 徐仁扣[1] 肖双成[1] 

机构地区：[1]中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室 [2]南京农业大学资源与环境学院,南京210095

出　　处：《安全与环境学报》2007年第2期15-17,共3页Journal of Safety and Environment

基　　金：国家自然科学基金资助项目(20577054)

摘　　要：利用膨润土原矿提取了粒径小于2μm的膨润土胶体,经过钠质化处理后分别用聚羟基铁和聚羟基铝进行改性,然后用一次平衡法研究了改性膨润土对水体中铬酸根的吸附性能。结果表明,与原矿相比,改性膨润土对铬酸根的吸附量有了不同程度的提高,铁改性膨润土对铬酸根的吸附量大于铝改性者。CrO42-的吸附平衡浓度为0.5mmol·L-1时,Mt-1(Fe)、Mt-2(Fe)和Mt-3(Al)对铬酸根的吸附量分别为271.0mmol·kg-1、114.0mmol·kg-1和16.1mmol·kg-1。改性膨润土对铬酸根的吸附量随离子强度的增加而增大,随体系pH值的增加而减小。铬酸根在改性膨润土表面的吸附以专性吸附机制为主,静电吸附所占比例很小,一般不超过30%。这些研究结果可为开发新型水处理剂提供理论指导。Clay fraction less than 2μm in diameter was separated from a bentonite collected from Nanjing suburb by decantation and then Fe/Al modified bentonites were prepared from bentonite colloid after it was saturated with Na^ ＋ in this study. Adsorption of CrO4^2- by Fe/Al modified bentonites was investigated with a batch method. The results of our study have shown that a noticeable increase in CrO4^2 - adserption by Fe modified bentonite than the one modified by AL. When the equilibrium adsorption concentration was 0.5 mmol·L^-1, the amount of CrO4^2- adsorbed by Mt-1（Fe）, Mt-2（Fe） and Mt-3（A1） was271.0 mmol·kg^-1, 114.0 mmol·kg^-1 and 16.1 mmol·kg^-1, respectively. Since the amount of CrO4^2- adsorbed by Fe/Al modified bentonites increases with the increase in the ion strength and decreases with the increase of pH, the adsorption of CrO4^2- may involve specific and electrostatic interaction of CrO4^2 - with the modified bentonites. The specific adsorption can be thought of as the main mechanism for CrO4^2- under the experimental conditions in this study. The contribution of electrostatic adsorption proves less than 30% of the total adsorption of GrO4^2- . Thus, the results obtained are expected to provide a useful reference to developing new doses for waste water treatment.

关 键 词：环境化学 Fe/Al改性膨润土 铬酸根 吸附-解吸 

分 类 号：X131.3[环境科学与工程—环境科学]