Fe-Mn-alginate: a highly effective adsorbent for arsenic removal

Abstract

This study examines the potential of iron-manganese-alginate (Fe-Mn-Alg) as a promising adsorbent for the effective removal of arsenic from water. The synthesized adsorbent was characterized using FTIR, XRD, SEM, and BET analyses. FTIR identified functional groups involved in arsenic adsorption, SEM revealed surface morphology, BET measured surface area and pore structure, and XRD confirmed the crystalline phases of iron and manganese oxides in the Fe–Mn–Alginate composite. Existing studies suggest that Fe-Mn-Alg exhibits optimal arsenic removal at a molar ratio of 2.5:10 (or 1:4). Characterization techniques, including BET analysis, reveal that the synthesized adsorbent is predominantly non-porous or macroporous, with a specific surface area of 0.0836 m2/g and a pore size of 34 nm, indicating sufficient surface area for effective interaction with arsenic ions. Fe-Mn-Alg exhibits a high arsenic adsorption capacity of 71.4 mg/g, surpassing that of many conventional adsorbents. Its competitive advantage lies in the synergistic effect of iron and manganese oxides, efficient dispersion within the alginate matrix, and the macroporous structure that enhances ion diffusion and accessibility to active sites. The study also highlights key factors influencing arsenic adsorption, such as contact time, pH, and adsorbent dosage. Optimal removal occurs at a pH of 7, reaching equilibrium after approximately 150 minutes of contact time. These findings highlight the crucial role of environmental conditions in facilitating arsenic uptake.