A mussel-induced approach to secondary functional cross-linking 3-aminopropytriethoxysilane to modify the graphene oxide membrane for wastewater purification

摘要

Graphene oxide(GO)with one-atom-thick exhibit remarkable molecule sieving properties,but its low permeance flux renders it difficult to be applied in practice as a high-permeance separation membrane.In this study,we design complex membrane from covalently crosslinked GO,polydopamine(PDA),and 3-aminopropytriethoxysilane(APTES)as building blocks to fabricate the high-permeance GO-based membrane via the vacuum filtration method.A branched crosslinking product(PDA/APTES)working as a clamp grasped the hydrophilic functional groups(hydroxyl,epoxy,carboxyl)on GO for improving the GO membrane flux.The interlayer structure of the GO membrane was optimized according to the crosslinker concentration,reaction time,initial p H,and temperature for RGO/PDA/APTES(RGPA)in this study.At the optimized reaction conditions including the crosslinker concentration of 1.4 m L/L,the temperature of 80°C,the time of 16 h,and the initial p H of 8.5 for RGPA mixture,the interlayer gallery of RGPA membrane was effectively tunes,endowing high flux ranging from 11.98 L m^(-2)h^(-1)to 1823.97 L m^(-2)h^(-1).Besides,the RGPA membrane ensured the high rejections to dye solutions such as methylene blue(MB)(>99%)and congo red(CR)(>90%).Meanwhile,the superior reusable performance of the RGPA membrane was achieved,together with the rejections for MB and CR to 96.32%and 93.1%after 4 cycles,respectively.Also,the RGPA membrane possessed superior anti-fouling performances for bovine serum albumin(BSA)aqueous solution and excellent stabilities in harsh conditions(p H 3,7 and 11).Grafting the crosslinker onto GO nanosheets exhibits the distinct advantages of achieving the high flux,high rejections to dyes,and superior reusable performance of membranes,posing a great application potential for membrane separation technology in wastewater treatment.