Ferric ions mediated defects narrowing of graphene oxide nanofiltration membrane for robust removal of organic micropollutants

Removal of organic micropollutants (OMPs) in the wastewater treatment is greatly important due to their adverse effects on human health and ecosystem. In this work, we provide a new perspective to prepare graphene oxide (GO) nanofiltration (NF) membrane with narrow pore size distribution for robust removal of OMPs. Ferric ions (Fe 3+ ) mediated GO nanosheets are firstly used to prepare GO membrane, then the membrane surface is modified by a targeted coating layer consisting of tannic acid-aminopropyltriethoxysilane (TA-APTES) via their strong affinity to Fe 3+ , where the larger membrane defects with more Fe 3+ would be patched by thicker TA-APTES. Such “speckled” TA-APTES coating can simultaneously enhance antifouling ability and regulate nanochannels of the GO membrane. The resulted GO membrane shows high and steady rejections on various OMPs, even in the long-term operation, cross-flow filtration or under high-pressure. This work proposes an innovative idea for constructing hydrophilic surface and narrow pore size distribution of NF membrane.