Removal of As(III) in water using ZnFe2O4 decorated biochar derived from bagasse

Abstract

Arsenic (As) contamination in water poses a significant risk to human health, particularly due to the toxic and mobile nature of arsenite (As(III)). In this study, ZnFe₂O₄ decorated onto biochar derived from bagasse (ZnFe₂O₄@Biochar) was successfully synthesized for efficient removal of As(III) from aqueous solutions. The synthesized material was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and magnetization. The XRD and FTIR results confirmed the successful incorporation of ZnFe₂O₄ onto biochar, while SEM and EDX revealed a highly porous structure with evenly distributed nanoparticles. The composite also showed high magnetization separation. Batch adsorption experiments were conducted to evaluate the effects of contact time, temperature, and pH on adsorption efficiency. The adsorption kinetics followed a pseudo-second-order model, indicating chemisorption as the primary mechanism for As(III) removal. Adsorption isotherms were best described by the Freundlich model, suggesting heterogeneous surface adsorption with a maximum adsorption capacity (q_max) of 1348.2 μg/g. The adsorption process was found to be endothermic, with increasing temperature enhancing adsorption efficiency. The optimum pH for As(III) removal was 3, where electrostatic interactions and chemical bonding were most favorable. This study showed that ZnFe₂O₄@Biochar is a highly efficient, sustainable, and cost-effective adsorbent for As(III) removal and could be a significant potential material for application in water treatment systems.