Fabrication and Characterization of Chitosan/TiO₂ Membranes for Scenedesmus Remediation

Abstract

Excess nutrients from human activities have triggered harmful algal blooms (HABs), degrading water quality and ecosystem health. Traditional control methods like ultrasonication and chemical coagulants are limited by high costs and risks of secondary pollution. To address these challenges, this study investigates the use of polymeric membranes as a cost-effective and sustainable solution. Specifically, the study focuses on the development and evaluation of chitosan/TiO₂ composite membranes for the removal of HABs. FTIR analysis confirmed the successful incorporation of TiO₂, as indicated by the presence of Ti–O stretching vibrations at 467–457 cm⁻¹ in the chitosan/TiO₂ composite. TGA results revealed that membranes with higher TiO₂ content exhibited lower weight loss, with the 1:2 chitosan/TiO₂ composition showing a weight loss of 49.61%. Algae removal efficiency was assessed using light microscopy at different time intervals: 30 minutes, 1 hour, 4 hours, and 8 hours. The chitosan-based membranes demonstrated high algae removal efficiency, with chitosan alone achieving 37.64%, 1:1 chitosan/TiO₂ reaching 42.63%, and 1:2 chitosan/TiO₂ achieving the highest at 60.56%. A nitrate absorption test was also conducted to evaluate nutrient removal capacity. Interestingly, the chitosan-only membrane exhibited the highest nitrate absorption (33.98%), while the chitosan/TiO₂ composites showed reduced absorption efficiency. These findings highlight the potential of chitosan/TiO₂ composite membranes for treating HAB-affected water through dual mechanisms: algal removal and nutrient reduction. Such membranes could be integrated into water treatment facilities, aquaculture systems, and lake restoration initiatives to mitigate HABs and enhance water quality.