(571a) Construction of Graphene Oxide (GO) Framework on Hollow Fiber Membranes Via Layer-By-Layer Approach for Heavy Metal Removal

A layer-by-layer (LbL) approach was employed to deposit an ultrathin graphene oxide (GO) framework layer on a modified Torlon^® hollow fiber support, enabling the composite membrane with superior nanofiltration (NF) performance. The GO framework was molecularly designed following the 2-step method: repeated GO and ethylenediamine deposition and an amine-enrichment modification by hyperbranched polyethylenimine (HPEI). Surface characterizations by SEM, XPS and zeta potential confirmed the formation of the GO framework structure. A 5 to 10 deposition cycle was proven efficient to seal the surface defects, reduce the pore size and narrow down the pore size distribution of the composite membranes. The synergistic combination of the GO framework layer and the Torlon^® support can effectively reduce the polymer consumption for the fabrication of traditional integrally skinned NF membranes. The GO/Torlon^® composite membrane has rejections higher than 95% towards Pb²⁺, Ni²⁺, and Zn²⁺ with a superior water permeability of 4.7 L m^â??2 h^â??1 bar^â??1. The membrane also exhibits excellent long-term performance stability during a 150-h NF test. Thus, the newly developed membrane has great potential for heavy metal removal and may provide useful insights on the fabrication of new generation 2-dimensional (2D) NF membranes.