水热辅助溶胶-凝胶法制备分等级拟薄水铝石/PVA复合薄膜及其Cr(Ⅵ)吸附性能

Hydrothermal assisted sol-gel method for preparation of hierarchical pseudoboehmite/PVA composite film and their adsorption performance towards Cr(Ⅵ)

在调节偏铝酸钠溶液pH制备氢氧化铝溶胶的基础上,以聚乙烯醇(PVA)为成膜剂,结合水浴、水热和焙烧等过程,制得了拟薄水铝石/PVA复合薄膜,采用扫描电镜对产物的微结构和形貌进行表征,并对比研究了PVA和水热处理对产物Cr(Ⅵ)静态吸附性能的影响。研究表明:添加PVA可以有效地促进拟薄水铝石溶胶成膜,而不添加PVA只能得到粉体样品;加入PVA后水热辅助溶胶-凝胶法制备的分级拟薄水铝石/PVA复合薄膜对Cr(Ⅵ)具有优异的吸附性能,Cr(Ⅵ)初始浓度为20mg/L时在4h左右即达到吸附平衡,平衡吸附率达82.3%,循环2次后的平衡吸附率分别为76.4%和73.9%。相比之下,加入PVA后直接水浴加热处理得到分级拟薄水铝石/PVA复合薄膜的吸附性能较差,需要8h才能达到吸附平衡,平衡吸附率为74.7%;不加PVA时拟薄水铝石粉体在8h时对Cr(Ⅵ)溶液的吸附率仅为40.3%。

Based on adjusting the pH of sodium aluminate solution to prepare aluminium hydroxide sol,a pseudoboe hmite/polyvinyl alcohol （PVA） composite film was synthesized by combination with water bath, hydrothermal treatment and calcination using PVA as a film former. The mierostructures and morphologies of samples were characterized by SEM, and the effects of the addition amount of PVA and hydrothermal treatment on their static adsorption performance towards Cr（ Ⅵ ） were comparatively studied. The results showed that PVA can effectively promote the film formation of pseudoboe hmite sol. However,only powders can be obtained without PVA. The as prepared hierarchical pseudoboehmite/PVA film showed excellent adsorption performance towards Cr（ VI ）. Its adsorption reached equilibrium within 4h when the initial con centration of Cr（Ⅵ） was 20mL/g,and the equilibrium adsorption rate was 82.3%. After its recycling regeneration for the 1st and 2nd times in turn, the adsorption rate reduced to 76.4% and 73.9% ,respectively. In contrast, the pseudoboehmite/ PVA fihn prepared by directly water bath heating had inferior adsorption performance,and its adsorption reached equilibri um within 8h with an equilibrium adsorption rate of 74.7%. Furthermore, the adsorption rate of pseudoboehmite powder prepared without PVA was only 40.3% after 8h.