铝柱撑膨润土吸附处理水中磷酸根和结晶紫

Adsorption of aqueous phosphate and crystal violet on Al-pillared bentonite

采用不同添加量(1~4 mmol/g)的聚合羟基铝离子(Al13)柱撑改性膨润土,制得系列铝柱撑膨润土(Al13-Bent)。采用X射线衍射、热分析、N2吸脱附比表面积分析等表征分析了其结构特点,比较了不同添加量Al13-Bent对水中磷酸根与结晶紫的吸附性能。结果显示,随着Al添加量增大,Al13-Bent的比表面积增大,柱撑产物的底面间距在添加量为2 mmol/g后达到最大,稳定于1.9 nm左右。Al13-Bent对水中磷酸根的吸附效果好于原始膨润土,且随着Al含量增加而提高。Al13-Bent在低Al添加量下对水中结晶紫虽有较好的吸附能力,但其吸附性能相比于膨润土原土却有所下降。就其吸附机理来看,层间域内Al13离子表面羟基与层间阴离子促进了对阴离子含氧酸根的吸附;由于Al13柱撑后,层间可交换阳离子减少,导致对阳离子型染料的吸附性能下降。

A series of pillared interlayered clays(Al13-Bent) were synthesized by modifying bentonites with polyhydroxy aluminum(Al13). The products prepared with different amounts of aluminum added(1–4 mmol/g) were characterized by X-ray diffraction, thermogravimetric analysis, and nitrogen adsorption-desorption isotherms. The adsorption of aqueous phosphate and crystal violet onto Al13-Bent were examined. The results show that the basal spacing and the surface area of Al13-Bent increase with increasing aluminum content of Al13-Bent. The resulting Al13-Bent was shown to be more effective in adsorption of phosphate from water than the raw bentonite. The hydroxyl groups on Al13 cations and anions in the interlayer spaces of Al13-Bent are largely beneficial to the removal of phosphate. However, with increasing intercalated Al13, the removal of crystal violet by Al13-Bent decreases more in comparison with raw bentonite. The intercalation of Al13 reduces the cation exchange capacity of Al13-Bent, which is responsible for the decrease of cationic dye removal.