Porosity and Hydrophilicity Enhancement of Hybrid Polysulfone Membranes using k-Carrageenan as Biopolymer Additive

Abstract

Membrane separation technology has been widely used in the process of treatment of water and wastewater. Polysulfone (PSf) membranes exhibit robustness and flexibility in this application. Nevertheless, the hydrophobic nature of PSf impedes the flow of water and reduces the effectiveness of membrane filtration. Hence, the properties of PSf membranes can be enhanced with the incorporation of kappa-carrageenan (ƙ-car), a hydrophilic biopolymer. This study examined the use of ƙ-car, a biopolymer made up of anionic polysaccharides derived from certain species of ocean red algae. The goal was to address issues connected to the membrane's hydrophilicity and selectivity. The membranes produced with various weight percentages of ƙ-cars (0.1, 0.25, 0.5, 0.75, and 1.0) are denoted as C1, C2, C3, C4, and C5, respectively. The hybrid PSf/ƙ-car membranes underwent characterization using FTIR, water contact angle (WCA) goniometer, and FESEM. The inclusion of ƙ-car substantially enhanced the hydrophilic properties of PSf membranes. The results indicated that C2 with 0.25 wt.% ƙ-car addition resulted in the highest porosity, reaching 79%. The presence of an extra-OH signal at 3385.31 cm-1 in the nanohybrid membrane's FTIR spectra suggests an enhancement in hydrophilicity due to the hydroxyl (-OH) groups of ƙ-car. The water contact angle improved from 68.52˚ to 43.28˚, indicating an improvement in hydrophilicity. The arrangement of the finger-like structure of the hybrid membrane is slightly curved with a bigger lower section. Above all, C2 has demonstrated the highest level of salt removal, reaching up to 97%. This discovery demonstrated that the inclusion of 0.25 wt.% ƙ-cars significantly improved water permeability and its ability to reject salt and dye too. Overall, the addition of ƙ-car as a pore former in the fabrication of the PSf membrane has significantly affected its ability to attract water, its ability to selectively allow certain substances to pass through, and its physical structure.