Cigarette butt waste as material for phase inverted cellulose acetate membranes synergistically incorporated with silver/copper oxide (CA-Ag/CuO) for reverse osmosis water treatment

Abstract

The improper disposal of cigarette butts presents a significant environmental challenge, yet their cellulose acetate (CA) content offers the potential for upcycling into functional materials. In the study, the potential of using CA waste obtained from cigarette butts for fabricating CA phase-inverted membranes is demonstrated. The CA membranes were impregnated with silver (Ag) and copper oxide nanoparticles (CuO) simultaneously to improve permeation flux and salt rejection during reverse osmosis. The effect of the variation of Ag/CuO on the CA membranes was probed using Fourier transform infrared spectroscopy (FTIR) which confirmed the successful introduction of Ag/CuO NPs into the CA matrix. The effect of the nanoparticles on the membrane morphology was assessed using scanning electron microscopy (SEM). An increase in the contact angle measurements concurrent with higher nanoparticle loading was observed, indicating an improved membrane hydrophilicity. Membrane performance was evaluated using a crossflow RO test whereby a significant increase in pure water flux (up to 73.33 Lm⁻² h⁻¹ for CA_0.15 (Ag/CuO)) and effective desalination of a 30 000 ppm NaCl solution under 4 bar pressure was observed. The rejection of NaCl was 92%, alongside a flux recovery ratio (FRR) of 94% at the optimal nanoparticle concentration. Additionally, the nanocomposite membranes demonstrated strong anti-scaling behavior, as evidenced by the reduced irreversible fouling and improved FRR. Overall, the current study highlights the dual benefits of environmental waste valorization, offering a viable, low-cost fabrication alternative to conventional membranes. Furthermore, the use of bio-based CA ensures easier biodegradation compared to other polymers. Consequently, the cigarette butt-derived CA-Ag/CuO membranes present an effective and environmentally suitable solution for saline water desalination, particularly in rural areas.