Graphene oxide/multi-walled carbon nanotubes nanocompsite polyamide nanofiltration membrane for dyeing-printing wastewater treatment

Graphene oxide (GO)/multi-walled carbon nanotubes (MWCNTs) modified nanofiltration (NF) membranes were successfully fabricated by interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricarbonyl trichloride (TMC). Compared with the pristine polyamide (PA) membrane and GO membrane, the typical structure of the granular protrusions on the surface of the GO/MWCNTs membrane gradually disappeared, and a regular ordered morphology appeared. The membrane thickness and surface roughness were increased according to the results of field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The contact angle of GO/MWCNTs NF membranes progressively decreased from 57° to 23°, indicating the enhancement of surface hydrophilicity. The best NF performance was achieved when the ratio of GO to MWCNTs was 6:3 (G-M-3). The water flux was 55.6 L/m 2 .h, which was 33.7% higher than that of the GO membrane, and the rejection rate for Na 2 SO 4 was maintained at approximately 94%. Both modified NF membranes could treat actual dyeing-printing wastewater effectively. The anti-fouling performance of G-M-3 was better than that of G3. Therefore, GO/MWCNTs-modified NF membranes have a good application prospects in the field of wastewater treatment and water purification.