Adsorptive Removal of Arsenite and Cobalt by Commercial Sorbents

Despite the prevalence and toxicity of heavy metals in the environment, arsenic and cobalt are of particular concern due to their high mobility and bioaccumulation potential, particularly in contaminated groundwater. Herein, we studied the adsorption behavior of commercially available sorbents, including Fluorosorb-100 (FS-100), Fluorosorb-200 (FS-200), and Filtrasorb-400 (F-400), for the removal of arsenite (As(III)) and cobalt (Co(II)), aiming at the selection of filter media in terms of future groundwater remediation. Kinetic analysis revealed that As(III) adsorption followed a pseudo-second-order model, while Co(II) showed mixed first- and second-order behavior, reflecting sorbent-dependent mechanisms. Equilibrium isotherm modeling revealed strong correlations with both Langmuir and Freundlich models, confirming heterogeneous adsorption sites and multilayer interactions. FS-100 demonstrated the highest affinity for As(III) (qₘ = 0.46 mg/g) and F-400 exhibited the greatest adsorption capacity for Co(II) (qₘ = 1.00 mg/g), while FS-200 consistently showed relatively weaker adsorption for both metals. Desorption studies indicated predominantly irreversible binding, with minimal release of As(III) from F-400 and Co(II) from FS-200 and F-400, even at high concentrations. Overall, these findings highlight that commercially available sorbents can effectively capture arsenite and cobalt, offering cost-effective and scalable options for heavy-metal removal in groundwater remediation systems under realistic environmental conditions.