Enhancing polyethersulfone membrane durability and stability through Eco-friendly green silica from natural kaolin for water treatment applications

Membrane technology is pivotal in addressing global water scarcity; however, issues such as membrane fouling and chemical degradation significantly hinder its operational efficiency and longevity. This study investigates the use of eco-friendly green silica derived from natural kaolin as an additive to enhance the performance of polyethersulfone (PES) membranes fabricated via the phase inversion method. Seven membrane compositions were developed, incorporating varying concentrations of both green silica and commercial silica, to allow a direct performance comparison. The membranes were systematically characterized for hydrophilicity, porosity, pore size distribution, and mechanical stability, while their filtration performance was evaluated in terms of water flux, humic acid (HA) rejection, fouling resistance, and chemical stability.The findings revealed that green silica enhanced membrane hydrophilicity and porosity at optimal concentrations, leading to improved fouling resistance and cleaning efficiency. Notably, the membrane containing 1 % green silica (M-K3) exhibited a high HA rejection rate of 98.37 % with a moderate water flux of 10.85 L/m²·h, balancing selectivity and permeability. In contrast, membranes containing 1 % commercial silica (M-S3) showed higher water flux (86.83 L/m²·h) but lower HA rejection (73.75 %), highlighting a trade-off. Green silica-modified membranes also demonstrated superior chemical stability, maintaining consistent performance under extended filtration and exposure to cleaning agents. These results underscore the potential of kaolin-derived green silica as a cost-effective, sustainable, and high-performance alternative to commercial additives in water treatment membranes.