Robust Janus nanocomposite membrane with opposing surface wettability for selective oil-water separation

A robust and facile strategy were facilitated to generate a Janus nanocomposite membrane showcasing asymmetric oil and water separation capability. The Janus membrane architecture was governed by incorporating organosilane functionalized carbon nanotubes (f-CNT) layer onto the crosslinked hydrophilic electrospun polyvinyl alcohol (c-PVA) membrane through simple vacuum filtration. The functionalization of fluorine-bearing 1H,1H,2H,2H-perfluoroctyltriethoxysilane (PFOTS) onto the CNT led to the increase in the hydrophobicity of the interface. This technique induced the CNT decorated surface to effectively separate water-in-oil emulsions. The integration of the PFOTS onto the CNT deposition not only enhanced the interfacial hydrophobicity but also assisted the linking compatibility between CNT and the c-PVA membrane which can be accounted onto the robust mechanical stability of the designed Janus membrane. Moreover, the utilization of free standing PVA on emulsion separation had not been explored in any publication. The hydrophilic nature, crosslinking modification and highly porous network of the fabricated c-PVA membrane makes it ideal for oil-in-water separation. The obtained asymmetric Janus membrane demonstrated an excellent oil and water selectivity from various emulsions which makes the Janus membrane promising on several applications.