Biomass Valorization Through Applications in the Continuous Removal of Iron from Water: Batch Equilibrium and Fixed-Bed Adsorption

Iron is one of the most common constituents in groundwater, and affordable decentralized options for removing residual iron remain limited. This study valorizes two abundant agro-industrial residues, sugarcane bagasse and green coconut mesocarp, as biosorbents for removing residual iron from water, using iron(III) as the model adsorbate. The materials were characterized by SEM, FTIR, EDS and pHPZC analyses, and their performance was evaluated through batch equilibrium and fixed-bed adsorption experiments. Simple, low-intensity pretreatments improved performance without high-temperature activation or hazardous reagents. Batch equilibrium isotherms were best described by the Sips model (Adj. R2 > 0.97), with model-predicted maximum capacities of 0.25 and 0.56 mg·g−1 for treated bagasse and mesocarp, respectively. Translated to continuous operation, fixed-bed columns achieved capacities of 0.66 and 0.44 mg·g−1, with breakthrough behavior well captured by the Thomas, Yoon–Nelson, and Yan models. Although capacities are modest, they are well matched to the low iron levels typical of point-of-use polishing, where very low material cost and wide availability outweigh raw capacity. By converting waste that is otherwise landfilled into functional treatment media, this work offers a practical, circular-economy route toward safer drinking water in decentralized, resource-limited settings.