Modified ceramic filters as a local solution for Hg (II) and As (V) removal from polluted surface drinking waters

Unregulated mining activities can pollute surface drinking water sources with toxic metals such as arsenic and mercury, creating serious environmental and public health concerns in resource-limited communities. In this study, locally fabricated ceramic water filters prepared from clay and different biosorbents were evaluated for the removal of As(V) and Hg(II) from contaminated water. Three ceramic formulations were produced using rice husks, sheanut shells, and groundnut shells as pore-forming and functional biosorbent additives. Batch adsorption and full-pot filtration experiments were conducted to determine removal efficiency, the effects of initial concentration, contact time, and adsorbent dosage, as well as the practical filtration performance of the developed filters. Structural characterization using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the sheanut-shell-based material (CMS) possessed a higher amorphous fraction and smaller crystallite domains, features that are favorable for adsorption. Among the tested materials, CMS exhibited the best performance, achieving a maximum Hg(II) removal efficiency of 80.7% at an initial concentration of 0.5 mg/L under the tested conditions. Kinetic data were better described by the pseudo-first-order model $$\left( {R^{2} \ge 0.99} \right)$$ , while equilibrium data were best fitted by the Freundlich isotherm model $$\left( {R^{2} \ge 0.99} \right)$$ , indicating adsorption on heterogeneous surfaces. Under filtration conditions, mercury removal was consistently higher than arsenic removal, with CMS showing the best overall performance. These findings demonstrate that biosorbent-modified ceramic water filters, particularly those incorporating sheanut shells, offer a promising low-cost and locally deployable option for the treatment of mining-impacted water.