Sustainable and eco-friendly membranes from sugarcane bagasse: An upcycling approach for wastewater treatment and energy storage

Developing eco-friendly alternatives to synthetic membranes is crucial in advancing modern membrane technology for water purification. In a pioneering effort, sustainable free-standing Forward Osmosis (FO) membranes composed of cellulose-derived from waste agricultural sugarcane bagasse (SBC) and PVA were developed. These membranes represent a novel upcycling approach, offering both biodegradability and sustainability while ensuring the production of high-quality water. Various analytical techniques were employed to characterize the SBC and membranes. The SBC exhibited a surface area of 1.9 m² g⁻¹, as determined by BET analysis and was rich in various functionalities. Membrane contact angle measurements revealed their hydrophilic nature. The optimized membrane, SBC-15-DS, demonstrated remarkable performance with an osmotic water flux (OWF) of 9.5 ± 0.2 L m⁻²h⁻¹, reverse solute flux (RSF) of 0.23 ± 0.01 mol m⁻²h⁻¹, and specific solute flux (SSF) of approximately 0.009 mol L⁻¹, achieving > 99 % retention for all pollutants. Notably, flux rates of 11 to 14 L m⁻²h⁻¹ with 99 % rejection were attained for various real industry wastewaters. The SBC-15-DS membrane exhibited excellent stability over 216 h without backwashing, and its biodegradability was confirmed through mulching. Furthermore, fouled membranes were recycled through pyrolyzing at 900 °C, yielding carbon for fabricating supercapacitor electrodes. These electrodes exhibited a specific capacitance of 115 F g⁻¹ at a current density of 0.1 A g⁻¹. Thus, these membranes hold promise for the advancement of sustainable and eco-friendly water purification methods in FO processes.