氧化石墨烯-陶瓷复合纳滤膜的层层自组装制备及其性能

摘要

Graphene oxide (GO) can be quickly deposited on a positively charged porous matrixvia a layer-by-layer self-assembly strategy because GO nanosheets contain rich negatively charged, oxygen-containing function groups, such asCOOH. In this paper, the GO-ceramics composite nanofiltration membrane was preparedvia layer-by-layer deposition of GO solution and eolyethyleneimine (PEI) solution alternately, and then cross-linked by epoxy chloropropane (ECH) on 3-aminopropyltriethoxysilane-modified porous Al2O3 supports. The optimum preparation conditions were: PEI 5g·L-1, pH=9; NaCl 0.3 mol·L-1; GO 0.6 mg·L-1, pH=4.5; ECH 6.25 ml·L-1 and heat treatment 50℃/70 min. Under the conditions of 0.6 MPa, when the self-assembly layer number increased from 1 to 4, the rejection to 2 g·L-1 MgCl2were 90.16%, 93.71%, 97.54%, and 92.93% respectively,and the flux of self-assembled monolayer membrane was 21.92 L·m-2·h-1. The rejection orders of inorganic salts of GO-ceramics composite nanofiltration membrane were as follows: MgCl2>MgSO4>NaCl>Na2SO4, therefore they showed the typical positively charged nanofiltration membrane characteristics.%氧化石墨烯(GO)的片层边缘含有COOH等含氧官能团,因而带负电荷,可以在带正电荷多孔基体上通过层层自组装实现快速沉积.以由3-氨丙基三乙氧基硅烷(APTES)修饰的多孔氧化铝管式陶瓷膜为基膜,令GO和聚乙烯亚胺(PEI)以溶液形态在其表面交替沉积实现自组装,继以环氧氯丙烷(ECH)交联之,制备新型氧化石墨烯-陶瓷复合纳滤膜.最佳制备工艺是,PEI浓度5 g·L-1、pH=9,NaCl浓度0.3 mol·L-1,GO浓度0.6 mg·ml-1、pH=4.5,层数2层,ECH用量6.25 ml·L-1,50℃条件下处理70 min.层数为1~4层的自组装膜在0.6 MPa操作压力下对2 g·L-1的MgCl2的截留率分别为90.16%、93.71%、97.54%、92.93%,其中1层自组装膜的渗透通量为21.92 L·m-2·h-1.氧化石墨烯-陶瓷复合纳滤膜对4种无机盐的截留率大小为MgCl2>MgSO4>NaCl>Na2SO4,符合典型正电荷纳滤膜的特征.