Silver tungstate/magnesium oxide nanocomposite as a high-performance adsorbent for bromide removal from aqueous systems

Bromide contamination in water sources poses significant health and environmental concerns due to its transformation into carcinogenic disinfection byproducts (DBPs) such as bromate during water treatment. In this study, a silver tungstate-modified magnesium oxide nanocomposite (Ag₂WO₄/MgO, denoted as AgW@MgO) was synthesized and applied as an efficient adsorbent for bromide removal from aqueous solutions. The material was thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) surface analysis. Batch adsorption experiments were conducted to evaluate the influence of adsorbent dose, initial bromide concentration, contact time, and pH on removal efficiency. The adsorption equilibrium data were best described by the Langmuir isotherm (<i>R</i>² = 0.9603), with a maximum capacity of 1.01 mg g^-1, while the kinetics followed a pseudo-second-order model (<i>R</i>² = 0.9718), indicating chemisorption as the dominant mechanism. Intra-particle diffusion analysis further confirmed multi-step adsorption behavior. Regeneration studies demonstrated that AgW@MgO maintained up to 50% removal efficiency after four adsorption-desorption cycles. Application to real groundwater samples showed complete bromide removal, highlighting the material's potential for practical water treatment. Overall, AgW@MgO emerges as a cost-effective and sustainable adsorbent with high efficiency, reusability, and environmental relevance for bromide elimination from contaminated waters.