Tuning d-spacing of graphene oxide nanofiltration membrane for effective dye/salt separation

摘要

The interlayer spacing(i.e.,d-spacing)plays a crucial role in determining the selectivity and permeability of nanofiltration membranes.A high-throughput directional filtration can be achieved by designing and controlling the d-spacing.In this study,the d-spacing of a graphene oxide(GO)membrane was tuned and fixed to the desired value(approximately 0.79 nm)using a solution of polyethyleneimine(PEI)and GO at a PEI/GO mass ratio of15:1.The resultant PEI/GO was deposited on a polyacrylonitrile(PAN)substrate to form a robust composite nanofiltration membrane(a PEI/GO@PAN membrane).The as-prepared membrane exhibited an ultrahigh flux of117.8 L·m^(-2)·h^(-1),and the rejection values for Direct Red80(DR80)and Na_(2)SO_(4)reached 99.7%and<1.7%,respectively;these are desirable values for dye/salt separation.The PEI/GO@PAN membrane exhibited an excellent filtration performance,and had a longer lifespan and excellent reusability because of its reinforced nature.This work suggested that tuning the d-spacing with PEI would be an effective strategy to achieve the anticipated functions of nanofiltration membranes.