Layer-by-layer self-assembly preparation and performance of GO-ceramics composite nanofiltration membrane

Abstract

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MgCl_2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MgCl_2>MgSO_4>NaCl>Na_2SO_4,符合; 典型正电荷纳滤膜的特征。Graphene oxide (GO) can be quickly deposited on a positively charged; porous matrix via a layer-by-layer self-assembly strategy because GO; nanosheets contain rich negatively charged, oxygen-containing function; groups, such as COOH. In this paper, the GO-ceramics composite; nanofiltration membrane was prepared via 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 Al_2O_3 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) MgCl_2 were 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: MgCl_2>MgSO_4>NaCl>Na_2SO_4,; therefore they showed the typical positively charged nanofiltration; membrane characteristics