Iron/manganese oxide-decorated GO-regulated highly porous polyacrylonitrile hollow fiber membrane and its excellent methylene blue-removing performance

Abstract

Polyacrylonitrile (PAN) hollow fiber membrane wet-spun without any porogen usually has a wide pore size distribution, low porosity, and unstable porous structure. In this work, graphene oxide (GO) was selected as a structural optimizer to tune the porous structure of the PAN membrane. The results show that pore size and porosity increase from 156.4 nm and 37.0% to 590.8 nm and 81.4% as GO amount increases from 0 to 0.15%, which also causes a narrower pore size distribution. A simple and viable route of gradient hydrolysis, coordination, and oxidation was then adopted to decorate the PAN membrane with well-grown and well-dispersed iron/manganese oxide to achieve a functional membrane that could remove methylene blue (MB) from water stably and efficiently in the presence of H2O2. Compared with the membrane without GO, the functional membrane has a higher oxide decoration ratio, lower water contact angle, larger pores, higher porosity, and better mechanical property, and its MB solution flux is roughly two times higher than that of the membrane without GO. Additionally, the functional membrane can remove MB from the water after 30 cycles without any obvious efficiency attenuation; by contrast, MB removal efficiency induced by the membrane without GO attenuates remarkably after 25 cycles.