Fe–Al–Mn@chitosan based metal oxides blended cellulose acetate mixed matrix membrane for fluoride decontamination from water: Removal mechanisms and antibacterial behavior

The scientific community is yet to find a cost-effective solution for the widespread problem of fluoride contamination in groundwater. In this study, cellulose acetate based mixed matrix membrane (MMM) was prepared through a phase inversion method using mixed metal oxides nanoparticles-polymer composite (Fe–Al–Mn@chitosan) as nanofiller. Adsorption is the commonly known mechanism of fluoride removal through MMMs and also a reason for its limited performance in real applications. Fe–Al–Mn@chitosan loaded cellulose acetate-based mixed matrix membrane (1 m²) is capable to treat 4000 L fluoride contaminated water. It has been observed that fluoride ions rejection occurs initially through adsorption. Subsequently, membrane surface experiences electrostatic repulsion due to the development of negative surface charges. Excellent defluoridation performance was obtained due to the electrostatic repulsion between F⁻ and negatively charged MMM surface. The antibacterial test reveals that the MMM is less susceptible to microbial attack compared to cellulose acetate membranes. Fluoride rejection through membrane confirms that mixed oxide nanoparticles-polymer-composite loaded MMM is capable of removing F⁻ from water quite efficiently.