Amyloid-intercalated graphene oxide membranes for enhanced nanofiltration

We report on fast pressure-driven nanofiltration of strong GO membranes intercalated by protein amyloid fibrils. We investigate the effect of protein amyloid fibril loading on membrane properties including the membrane stability, microstructure, reflux rate, permeance, rejection rate and fouling resistance. With increasing amyloid fibrils, the membrane becomes smooth and resilient and can be reused for many times with little disintegration. Microstructure analysis shows that amyloid fibrils enable expansion of the interlayer spacing between GO sheets, leading to around 100% increase in average water permeance of the 100 nm thick membrane (15.6 L⋅m−2⋅hr−1⋅bar−1) compared to the neat GO membrane (8.8 L⋅m−2⋅hr−1⋅bar−1). The hybrid membranes display improved moderate ion rejection (44–51%) of heavy metal salts and high molecular rejection (>97%) of organic dyes. Antifouling performance is evaluated in terms of flux recovery ratio and fouling ratios. The incorporation of amyloid fibrils enable GO membranes to change from irreversible fouling to reversible fouling and the hybrid membrane exhibits significantly enhanced flux recovery (>95%). A possible nanofiltration mechanism is proposed to explain the observations.