Eco-friendly reduced graphene oxide@potash alum-based composite membranes for efficient separation of dyes and selective removal of contaminants from wastewater

Graphene oxide (GO)-based membranes have gained significant attention for various separation applications over the last decade. However, achieving and maintaining the stability, high permeance, and high rejection of the membrane are still challenging tasks for the scientific community. In this study, we fabricated a reduced GO@potash alum-based (rGO@PA) composite membrane via a simple vacuum filtration method by modifying GO nanosheets with potash alum as the active material. The incorporation of a natural source of alum enhances the membrane stability and facilitates efficient stacking, while the high porosity and hydrophilic nature of the composite improve mass transfer, resulting in superior permeability. The as-prepared rGO@PA composite membrane achieves a high water permeance of up to 180 ± 10 L m⁻² h⁻¹ bar⁻¹. Further, the rGO@PA composite membrane demonstrates excellent dye rejection for anionic dyes, e.g., Congo Red, Eosin Y, and Rose Bengal, achieving rejections of up to 99.9%, 99.8%, and 99.2%, respectively. Besides these, the membrane also shows great rejection for cationic dyes, such as 99.0%, 99.6%, and 99.2% for methylene blue, methyl green, and methyl violet, respectively. In addition, the as-prepared membrane maintains its performance for over 15 days under aqueous conditions, even after sonication. This study underscores the effectiveness of the rGO@PA hybrid membranes for wastewater treatment applications, offering a robust, cost-effective solution for environmental remediation applications.