Development of high-permeable PSf/PANI-PAMPSA composite membranes with superior rejection performance

Abstract Polysulfone is the most popular polymeric matrix material for fabrication of ultrafiltration membrane but suffers from its hydrophobic nature that caused low flux and fouling problems that limits its development and industrial applications. The blending PSf with hydrophilic polymers is an attractive and effective technique to improve the hydrophilicity of membrane. Here poly(2-acrylamido-2-methyl-1-propane sulfonic acid doped polyaniline was synthesized and used as a hydrophilic additive in polysulfone to obtain ultrafiltration range membranes with higher flux. Infrared results supported the increased hydrophilicity of the membranes with PANI-PAMPSA additive which is confirmed by dynamic contact angle analysis results as well. The cross-sectional SEM images revealed that the pristine and blend membranes were asymmetric structured and had dense skin layer, finger-like pores on the top and sponge-like pores underneath the porous support layer. Also, the skin layer of the membrane became thinner and denser with the addition of 0.1 and 0.25% and thicker with the addition of 0.5 additive ratio. The initial contact angles of P0, P1, P2 and P3 measured as 85, 81, 79 and 72°, respectively. Pure water permeability of the P0, P1, P2 and P3 membranes calculated as 14.0, 17.2, 23.4 and 21.3 L.m-2. h-1. bar-1, respectively. The rejection ratios of the prepared membranes increased from 90.1 (P0) to 95.8 and 98.4% for P1 and P2 membranes then decreased to 95.2% for P3 membrane. The rejection results indicated that the prepared membranes can be classified as ultrafiltration membranes with molecular weight cut-offs (MWCOs) lower than 66 kDa g mol−1.