Enhanced alcohol dehydration via robust polyelectrolyte membranes embedded with sulfonated graphene quantum dots

Abstract

This study explored the integration of sulfonated graphene quantum dots (SGQDs) into polyelectrolyte membranes to enhance their stability and pervaporation efficiency. Two cationic polyelectrolytes, poly(acrylamide-co-diallyldimethylammonium chloride) (P(AAm-co-DDA)) and poly(diallyldimethylammonium chloride) (PDDA), were used in conjunction with SGQDs. The number of bilayers was varied to assess their impact on membrane performance. Characterization techniques including attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and x-ray photoelectron spectroscopy (XPS) confirmed the successful integration of SGQDs within the polyelectrolyte membranes. Analyses of water contact angle and zeta potential indicated that the number of bilayers influenced the surface wettability and charge properties of the membranes. Pervaporation tests demonstrated that the SGQDs-P(AAm-co-DDA) system performed optimally at 1.5 bilayers, outperforming the SGQDs-PDDA system. The best-performing membrane achieved a permeation flux of 925 g/m²h and a water concentration in the permeate exceeding 98 wt%. Furthermore, this membrane exhibited stable performance for 168 h. These results suggest that SGQDs can significantly stabilize polyelectrolyte membranes through electrostatic interactions, effectively preventing membrane swelling when exposed to aqueous alcohol solutions. This stabilization contributes to enhanced pervaporation performance, making SGQD-enhanced polyelectrolyte membranes promising candidates for industrial separation processes.