Efficient Arsenic Adsorption by Montmorillonite‐Hydroxyapatite‐Chitosan Films Synthesized from Phosphogypsum Waste: Kinetics, Isotherms, and Thermodynamics

Abstract

Abstract Arsenic (As), a very toxic metal and predominantly manufactured by the phosphate industry, is a very critical environmental and health risk. In the current study, Montmorillonite‐Hydroxyapatite‐Chitosan (MMT‐HAP‐CTS) composite was synthesized from hydroxyapatite obtained through phosphogypsum, a waste residue of phosphate industry processing. The green process not only employs industrial waste but also achieves maximum arsenic removal efficiency in aqueous solutions. Structural integrity and functional properties of the composite were confirmed by characterization by Fourier Transform Infrared Spectroscopy (FTIR), X‐ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and Differential Thermal Analysis (DTA). The adsorbent exhibited the maximum adsorption capacity (q max ) as 85.49 mg/g under optimal conditions, with the thermodynamic prediction of spontaneous and exothermic nature of adsorption. The study proves MMT‐HAP‐CTS viability as an eco‐friendly, efficient material for removal of arsenic, being waste valorization as well as water decontamination contributor.