Defluorination of borehole water using activated clay and bauxite-laden polyvinyl alcohol hybrid membranes

Abstract

Fluoride contamination in drinking water is a major global concern because of its significant health hazards. In many regions in Ghana and some other parts of the globe, fluoride levels rise to high levels, which leads to severe cases of fluorosis and skeletal disorders. Despite improvements in treatment techniques, the necessity of more sustainable and affordable methods and materials to achieve compliance with recommended fluoride limits still remains. Membrane filtration has emerged as a key technique in advanced wastewater treatment, where control of membrane fouling is essential for the feasibility of the process. This study delves into the fabrication and evaluation of activated clay (AC) and bauxite (BXT) incorporated in polyvinyl alcohol (PVA) composite membranes (MPVA/BXT:AC) for mitigating membrane fouling during water defluorination. The physical and chemical characteristics of the membranes were examined using Fourier transform infrared (FTIR) spectroscopy, proton-nuclear magnetic resonance (¹H NMR), zeta potential (ZP), X-ray diffraction (XRD), and scanning electron microscopy equipped with EDS. Fluoride removal efficiency and membrane performance were evaluated by conducting water filtration experiments at varying filler concentrations. The results revealed that the MPVA/1BXT:2AC membrane exhibited remarkable fluoride removal efficiency, achieving up to a defluorination rate of 92.4% and a flux recovery rate of 82.6%, indicating its excellent antifouling performance. This membrane had higher porosity and pure water flux (PWF) values of 69.2% and 73.1 L m⁻² h⁻¹, respectively.