Fabrication and Characterization of <scp>PPSU</scp>/<scp>PES</scp> Blend Nanofiltration Membrane via <scp>VIPS</scp>‐<scp>NIPS</scp> Method for Effective Dye Rejection

ABSTRACT Industrial effluents, including dyes, pose a threat to the environment and human health, as they are resistant to reacting with oxygen; therefore, they are rarely biodegradable. Among the various processes, nanofiltration is an attractive process for separating dyes from water due to its economic efficiency. This work represents the fabrication of poly (phenyl sulfone) (PPSU)/poly (ether sulfone) (PES) blend nanofiltration membranes through vapor‐induced phase separation (VIPS) followed by immersion precipitation. The influence of polymer blend, exposure time, and coagulation bath composition on membrane characteristics and performance was studied. Results illustrate that an increment in exposure time caused a thinner top layer and changed the cross‐section morphology from finger‐like to sponge‐like. At PPSU:PES = 50:50 blend ratio, the pore radius significantly got larger than the neat polymers' fabricated membranes. The addition of N ‐methyl‐2‐pyrrolidone (NMP) in the coagulation bath causes the formation of smaller finger‐like voids at the top layers and a sponge‐like structure in the sub‐layers of membranes. The optimal conditions for the nanofiltration membrane were determined at 28 s VIPS time, an equal ratio of polymers, and pure water as the coagulation bath. Under these conditions, the distilled water permeability and Rose Bengal rejection were determined as 63.6 L/m 2 h and 77.11%, respectively.