铁柱撑膨润土的制备及其对Cr(Ⅵ)的吸附试验

Research on Manufacture of the Fe-Pillaring Bentonite and Its Absorption Properties of Cr(Ⅵ)

目的探讨铁柱撑膨润土对Cr(Ⅵ)吸附的影响因素及吸附机理,旨在研发一种无害经济的修复Cr(Ⅵ)污染土壤和地下水的可渗透反应墙(PRB)的反应介质.方法将铁柱撑膨润土作为Cr(Ⅵ)的吸附质,在原土进行钠化的基础上,对其进行柱撑改性并对改性过程中的影响因素进行分析和确定,将制备出的改性土用于对Cr(Ⅵ)的吸附处理并确定最佳吸附条件.结果通过正交试验确定最佳改性条件为:柱化剂的制备为n(OH-)/n(Fe3+)=1∶1.5,柱撑土制备时反应和老化温度为80℃,老化时间24 h.利用单因素试验考查各种因素对吸附效率的影响,试验结果表明在吸附剂用量4 g/L、吸附时间45 m in、pH为6的水体中Cr(Ⅵ)(30 mg/L)去除率达到92.3%,处理后Cr(Ⅵ)质量浓度达到地下水水质Ⅲ类标准.结论将铁柱撑膨润土作为PRB的反应介质应用于修复Cr(Ⅵ)污染的土壤和地下水是可行的.

The preparation method and its preparation factors of the modified bentonite were studied. Fe-pil- lared bentonite was used as the absorbent for Cr （Ⅵ ） to explore the absorption factors of the Fe-pillaring Bentonite on the Cr（ Ⅵ ）, with the aim of researching and developing a kind of harmless and economic reac- tion medium of Permeate Reactive Barrier in-situ remediation technology. On the basis of sodium bentonite, Pillared agent was used to modify the soil. The optimum conditions were determined through orthogonal experiment： Pillared agent： n （ OH^- ）/n （ Fe^3 ＋） = 1 ： 1.5 ; the chemical reaction and aging temperature in the preparation of pillared soil：80℃ ;aging time：24 h. The single-factor test was used to study the efficiency of absorption on a variety of factors and the conclusions indicate that when Fe-pillared bentonite dosage is 4 g/L,pH value is 6 and reaction time is 45 rain,the removal rate can achieve 92.3% with Cr（Ⅵ）concen- tration of 30 mg/L. The Cr（Ⅵ ）concentration of treated water is less than the national groundwater quality Ⅲ standard. It is feasible that Fe-piUared bentonite is used as the reaction medium of PRB to remedy the polluted soil and groundwater by the Cr（Ⅵ）.