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Ultra-thin graphene oxide films via contra-diffusion method: Fast fabrication for ion rejection
- Du, Yong, Zhang, Xi, Yang, Jing, Lv, Yan, Zhang, Chao, Xu, Zhi-Kang
- Journal of membrane science 2019
- artificial membranes, calcium, cations, crosslinking, electrostatic interactions, filtrates, graphene, graphene oxide, iron, magnesium, nanofiltration, potassium, sodium, sodium sulfate
- Membranes based on graphene or graphene oxide (GO) have received intensive studies recently for various separation processes. However, a great challenge lies in fast and facile fabrication of GO membranes with high salt rejection. Here we report for the first time that ultra-thin GO films with a good salt rejection can be fabricated via contra-diffusion-induced crosslinking based on cation-π and electrostatic interactions between cations and GO flakes. It only takes down to 5 min to construct a defect-free GO film. Various cations, including Na+, K+, Mg2+, Ca2+ and Fe3+, can be used as “crosslinkers” to endow the as-prepared GO membranes with highly tunable separation performance. The optimized GO membranes exhibit over 90% rejection of Na2SO4 with filtrate permeance of 4.3 L m−2 h−1 bar−1 during the nanofiltration process, which reaches to the performance upper limit of previously reported graphene-based membranes. Such a high performance should be attributed to the unique packing structures of the GO flakes crosslinked by cations and the thin and uniform GO selective layers.