Document Type : Original Article
Authors
1
Department of Chemistry, Faculty of Basic Sciences, Ayatollah Boroujerdi University, Boroujerd, Iran
2
Department of Chemistry, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3
‘‘Schiavello-Grillone’’ Photocatalysis Group, Dipartimento di Energia, Ingegneria dell’informazione e modelli Matematici (DEIM), Universita` di Palermo, Viale delle Scienze, 90128 Palermo, Italy
4
Department of Physics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
5
School of Engineering, University of British Columbia - Okanagan, 1137 Alumni Avenue, Kelowna, V1V 1V7, Canada
6
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
Abstract
This study investigates low-cost, reusable Fe₃O₄@Humic acid/montmorillonite core-shell nanocomposites as high-efficiency adsorbents for removing methyl orange (MO) dye from aqueous solutions. The nanocomposites were characterized using FT-IR, TEM, SEM, XRD, and BET/BJH analysis to assess structural and surface properties. The results to report the specific surface area (30.23 m²/g), total pore volume (0.098 cm³/g), and average pore diameter (in the mesoporous range of 1-10 nm) for the Fe₃O₄@HA/MMT composite. Adsorption efficiency was optimized over 300 minutes using response surface methodology (RSM) with a five-factor, three-level central composite design. Kinetic studies revealed that the process follows a pseudo-second-order model (R² > 0.99). Equilibrium data were evaluated using Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Harkins–Jura isotherms, with the Freundlich model providing the best fit, indicating multilayer adsorption on a heterogeneous surface. Thermodynamic analysis showed: The negative ΔG° values confirm spontaneity, while their magnitudes (-6.26–-9.86 kJ/mol) suggest physical adsorption. The positive ΔH° value (15.2 kJ/mol) confirms that the process is endothermic. Increased entropy (0.05 kJ/mol·K) points to enhanced surface disorder and MO-adsorbent interactions. The positive activation energy (Eₐ = 18.3 kJ/mol) further corroborates the endothermic nature. A near-zero sticking probability (S* ≈ 0) reinforces the physical adsorption mechanism. These findings highlight the nanocomposite’s potential as a sustainable, high-performance solution for dye wastewater treatment.
Keywords
