Fabrication of nanofiltration membrane with enhanced water permeability and dyes removal efficiency using tetramethyl thiourea-doped reduced graphene oxide

The contamination of freshwater bodies via inappropriately released wastewater can be effectively prevented using membrane separation methods at the point of industrial discharge. Graphene oxide (GO), an allotrope of carbon, has adjustable physicochemical characteristics and a lot of potential for environmental cleanup. Due to its narrow and variable interlayer spacing the flux and dyes removal ability of GO membrane is low. To resolve this problem, current study reports the fabrication of tetramethyl thiourea (TMTU)-doped reduced GO (TMTU@rGO) using microwave method. TMTU@rGO is nanoporous material with increased surface area and pore volume as compared to GO. The prepared TMTU@rGO was utilized for the fabrication of nanofiltration membrane to remove cationic and anionic industrial dyes such as Methylene blue (MB), Rhodamine B (RB) and Congo Red (CR). The TMTU@rGO composite-based nanofiltration membrane was characterized using various characterization techniques, i.e., FTIR, EDX, XRD, SEM, BET, AFM, contact angle and zeta potential. The TMTU@rGO composite-based nanofiltration membrane showed 99% rejection with 200 L m-2 h-1 bar-1 and 180 L m-2 h-1 bar-1 flux for MB and RB, respectively, and 98% rejection with 170 L m-2 h-1 bar-1 flux for CR. It remained very stable without compromising its rejection ability and permeability till 10 cycles. TMTU@rGO composite-based nanofiltration membrane showed excellent separation efficiency and negligible matrix effect during purification of industrial wastewater. These findings have confirmed that functionalized rGO-based nanofiltration membranes can work as efficient materials for the decontamination of aqueous environment at large scale.