Utilization of <i>Catla catla</i> Fish Scale for Eliminating Cr (III) and Co (II) Heavy Metals From Wastewater

ABSTRACT This comprehensive research focuses on the prospective use of Catla catla fish scales as a bioadsorbent for removing heavy metals, particularly Cr (III) and Co (II), from wastewater and determining which metal ion is more likely to be removed efficiently. The study incorporates a rigorous methodology, wherein fish scales were obtained, cleaned, and prepared, including both acid‐treated and untreated variants. A range of salt solutions with varying concentrations of metal ions are utilized to evaluate adsorption efficiency, and the impact of factors like initial metal ion concentration, chemical treatment of adsorbent, and contact time are systematically examined using UV‐Vis spectrophotometry. It was found that the starting concentration of metal ions influenced the adsorption efficiency, with higher concentrations leading to a reduced adsorption capacity. The contact time also affected the adsorption efficiency, with longer durations resulting in increased metal removal until reaching equilibrium. Acid‐treated fish scales showed superior adsorption performance compared to the untreated ones. Characterization of the adsorbent is performed using advanced analytical techniques, including Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X‐ray spectroscopy (EDS), revealing changes in structural and chemical properties post‐metal adsorption. The adsorption equilibrium data are mapped to the Langmuir and Freundlich isotherm models, with Langmuir being more suitable for cobalt adsorption and Freundlich for chromium adsorption. This research highlights the economical and long‐term potential of Catla catla fish scales as a natural biosorbent, thereby significantly contributing to the domains of water purification and heavy metal pollution extenuation.