Low-pressure loose GO composite membrane intercalated by CNT for effective dye/salt separation

Abstract Low-pressure loose nanofiltration membranes were facilely fabricated by intercalating CNTs into graphene oxide (GO) laminates supported by cellulose acetate (CA) ultrafiltration substrates. The CNTs could loosen the GO laminar film and enlarge the interlayer spacing of GO laminates, thus reducing the resistance of water flux and salt permeation. Crosslinking bonds between GO layers were generated to create hydro-stable size-sieving channel necks of the tortuous pathway for selective molecular permeation. It was found that the GO composite membrane with 80 wt% of CNT content and 0.5 mg of GO loading exhibited the optimal separation performance in the application of textile wastewater treatment. It had the highest pure water permeability of 26.3 L·m-2·h-1·bar-1 and almost complete rejection to dyes (e.g. 98.7 % for Congo red, 94.1 % for Methyl blue) as well as the lowest rejections to salts (e.g. 3.1 % for NaCl, 6.3 % for Na2SO4) under a low transmembrane pressure of 1.0 bar. This work provides a feasible approach for designing GO-based membrane with improved dye/salt separation performance.