Magnetic Oxide Nano-Porous Adsorbents: A Highly Efficient Approach for Acid Fuchsin Removal from Medical Laboratory Effluents via Adsorption Process

Abstract Natural clay minerals offer a straightforward and industrially efficient pathway for the large-scale production of active silica materials exhibiting diverse morphologies and functions. However, the presence of magnetic oxide nanoparticles (Fe 3 O 4 ), enriched with metal ions, generated during this process has led to their classification as contaminants in laboratory effluents due to their specific adsorption of Acid Fuchsin Dye (AFD) in aqueous solutions. This study focuses on the characterization of clay minerals, particularly examining the interlayer spacing in smectites. Notably, the synthesis of Magnetic Oxide Nano-Porous Clay (MONPC) results in an approximate doubling of the specific surface area from 10.02 to m 2 g -1 compared to natural clay. The findings suggest a significant impregnation of Fe 3 O 4 within the Natural Clay (NC) matrix. The impregnated and natural clay samples were comprehensively characterized using XRD, SEM-EDS, FTIR, and N 2 adsorption-desorption techniques, confirming the presence of a porous surface structure with a high surface area. Utilizing an adsorbent concentration of 0.1 g/L, MONPC achieved complete removal of AFD from initial dye solutions with a 400 mg/L concentration which is attributed to the strong H-bonding ability of MNOPC with AFD dye as indicated by adsorption mechanism study. The adsorption capacity of AFD onto MONPC reached equilibrium within 60 to 120 minutes, with an initial pH of 9. The Pseudo-Second-Order model accurately depicted the chemisorption process of AFD adsorption, while the Freundlich isotherm model consistently provided a superior fit to the data compared to the Langmuir model. Thermodynamic analysis of the MONPC adsorbent demonstrated that the adsorption process was exothermic and spontaneous, with significant entropic changes at the solid-liquid interface. These results suggest that the adsorption of AFD dye onto MONPC was favorable in terms of enthalpy but unfavorable in terms of entropy. Considering the high surface area and enhanced adsorption capacity of MONPC, it exhibits tremendous potential as a promising adsorbent for the removal of AFD in wastewater treatment applications.