Ecofriendly Synthesis of Magnetic Composites Loaded on Rice Husks for Acid Blue 25 Decontamination: Adsorption Kinetics, Thermodynamics, and Isotherms

Fozia Batool; Samia Kanwal; Hafsa Kanwal; Sobia Noreen; Mohamed S Hodhod; Muhammad Mustaqeem; Gulnaz Sharif; Hafiza Komal Naeem; Javeria Zahid; Abdel-Rhman Z Gaafar

doi:10.3390/molecules28207124

Ecofriendly Synthesis of Magnetic Composites Loaded on Rice Husks for Acid Blue 25 Decontamination: Adsorption Kinetics, Thermodynamics, and Isotherms

Molecules. 2023 Oct 17;28(20):7124. doi: 10.3390/molecules28207124.

Authors

Affiliations

¹ Institute of Chemistry, University of Sargodha, Sargodha 40100, Pakistan.
² College of Biological Sciences and Medical Engineering, Donghua University, 2999 North Ren Min Road, Shanghai 201620, China.
³ Faculty of Biotechnology, October University for Modern Sciences & Arts, 6th October City 12566, Egypt.
⁴ Department of Chemistry, Government Graduate College for Women, Mandi Bahauddin 50400, Pakistan.
⁵ Department of Botany, University of Agriculture, Faisalabad 38000, Pakistan.
⁶ Department of Botany and Microbiology, College of Science, King Saud University, Riyadh P.O. Box 11451, Saudi Arabia.

Abstract

Addressing the growing need for methods for ecofriendly dye removal from aqueous media, this study explores the potential of rice husks coated with iron oxide (Fe₂O₃@RH composites) for efficient Acid Blue 25 decontamination. The adsorption potential of Acid Blue 25 is analyzed using raw rice husks and Fe₂O₃ nanoparticles in the literature, but their enhanced removal capacity by means of Fe₂O₃@RH composites is reported for the first time in this study. Fe₂O₃@RH composites were analyzed by using analytical techniques such as TGA, SEM, FTIR, BET, and the point of zero charge (pH_(PZC)). The Acid Blue 25 adsorption experiment using Fe₂O₃@RH composites showed maximum adsorption at an initial concentration of Acid Blue 25 of 80 ppm, a contact time of 50 min, a temperature of 313 K, 0.25 g of Fe₂O₃@RH composites, and a pH of 2. The maximum percentage removal of Acid Blue 25 was found to be 91%. Various linear and nonlinear kinetic and isothermal models were used in this study to emphasize the importance and necessity of the adsorption process. Adsorption isotherms such as the Freundlich, Temkin, Langmuir, and Dubinin-Radushkevich (D-R) models were applied. The results showed that all the isotherms were best fitted on the data, except the linear form of the D-R isotherm. Adsorption kinetics such as the intraparticle kinetic model, the Elovich kinetic model, and the pseudo-first-order and pseudo-second-order models were applied. All the kinetic models were found to be best fitted on the data, except the PSO model (types II, III, and IV). Thermodynamic parameters such as ΔG° (KJ/mol), ΔH° (KJ/mol), and ΔS° (J/K*mol) were studied, and the reaction was found to be exothermic in nature with an increase in the entropy of the system, which supported the adsorption phenomenon. The current study contributes to a comprehensive understanding of the adsorption process and its underlying mechanisms through characterization, the optimization of the conditions, and the application of various models. The findings of the present study suggest practical applications of this method in wastewater treatment and environmental remediation.

Keywords: Acid Blue 25; Fe2O3@RH composites; iron oxide; rice husk; toxic dye adsorbent.

Grants and funding

RSPD2023R686, King Saud University, Riyadh, Saudi Arabia./Abdel-Rhman Z. Gaafar, Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 11451, Riyadh, Saudi Arabia