Efficacy of phosphorus loaded oyster shell in heavy metal removal: A combined study on adsorption behavior, structure characterization and comparative mechanism

This study presents a comprehensive evaluation of unmodified and modified oyster shells (OS, MP-OS, MC-OS) as adsorbents for removing heavy metals (Cd2+ and Pb2+) from water. The modifications involved phosphoric acid treatment (MP-OS) and dipotassium phosphate calcination (MC-OS), aiming to enhance the adsorption capabilities of the shells. Experimental results demonstrated that MC-OS exhibited the highest adsorption capacity due to its optimal pore structure and surface properties. The kinetic and isotherm studies revealed that the adsorption process is predominantly governed by chemical adsorption, with notable contributions from physical adsorption mechanisms. Morphological and surface analyses, including SEM, XRD, and FTIR, highlighted significant changes in the shells post-modification, contributing to their enhanced adsorption performance. The study also compared the environmental and economic aspects of these modified shells with other adsorbents like hydroxyapatite and reed biochar. The findings suggest that modified oyster shells, particularly MC-OS, are highly effective, eco-friendly, and economically viable for heavy metal remediation in water, with potential applications in soil decontamination. This research offers valuable insights into the utilization of fishery waste for environmental management, demonstrating the effectiveness of chemical modification in transforming natural biowastes into potent adsorbents.