Photocatalytic Degradation of Polyethylene Microplastics Using Microwave-Activated Gadolinium Oxide Catalyst

Mohammad Luqman Ismail; Muhammad Farhan Hanafi; Norezatul Shahirah Ahmad Zamanhuri; Norzahir Sapawe; Umar Kalmar Nizar; Hairul Amani Abdul Hamid; Siti Munirah Sidik; Siti Fatimah Ibrahim; Mohammed Danish

doi:10.22146/ijc.108052

Photocatalytic Degradation of Polyethylene Microplastics Using Microwave-Activated Gadolinium Oxide Catalyst

https://doi.org/10.22146/ijc.108052

Mohammad Luqman Ismail⁽¹⁾, Muhammad Farhan Hanafi⁽²⁾, Norezatul Shahirah Ahmad Zamanhuri⁽³⁾, Norzahir Sapawe^(4*), Umar Kalmar Nizar⁽⁵⁾, Hairul Amani Abdul Hamid⁽⁶⁾, Siti Munirah Sidik⁽⁷⁾, Siti Fatimah Ibrahim⁽⁸⁾, Mohammed Danish⁽⁹⁾

(1) Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Bioengineering Technology (UniKL MICET), Lot 1988 Vendor City, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia
(2) Department of Chemical Engineering and Energy Sustainability, Faculty of Engineering, Universiti Malaysia Sarawak (UNIMAS), 94300 Kota Samarahan, Sarawak, Malaysia
(3) Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Bioengineering Technology (UniKL MICET), Lot 1988 Vendor City, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia
(4) Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Bioengineering Technology (UniKL MICET), Lot 1988 Vendor City, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia
(5) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang, Jl. Prof. Dr. Hamka, Padang 25173, Indonesia
(6) Fakulti Sains Gunaan, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor Darul Ehsan, Malaysia
(7) Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak, Malaysia
(8) School of Chemical and Process Engineering, University of Leeds (UL), LS2 9JT Leeds, United Kingdom
(9) Department of Chemistry, Faculty of Science, Islamic University of Madinah (IUM), Abo Bakr Al Siddiq Road, Al Jamiah District, Madinah 42351, Kingdom of Saudi Arabia
(*) Corresponding Author

Abstract

The persistent presence of polyethylene (PE) microplastics in aquatic environments poses serious environmental and health risks due to their resistance to conventional degradation methods. This study explores the photocatalytic degradation of PE microplastics using microwave-activated gadolinium oxide (Gd₂O₃) under visible light irradiation. Key operational parameters, including pH solution, catalyst dosage, and initial PE concentration were systematically investigated. Optimal degradation efficiency (68%) was achieved at pH 7, a catalyst dosage of 3 g/L, and a PE concentration of 10 mg/L. Kinetic analysis indicated that the degradation followed a pseudo-first-order model, with a maximum apparent rate constant (K_app) of 0.0103 min⁻¹ (R² = 0.9782). The degradation mechanism was further elucidated using the Langmuir–Hinshelwood kinetic model, suggesting a surface-mediated reaction with a high adsorption equilibrium constant (K_LH) of 0.4896 L/mg, indicating strong PE adsorption. The reduced degradation efficiency at higher PE concentrations was attributed to the limited generation of reactive oxygen species and increased light scattering. Overall, the findings demonstrate Gd₂O₃'s potential as an efficient, environmentally benign photocatalyst, contributing significantly to the development of rare-earth-based materials for sustainable microplastic remediation in water treatment technologies.

Keywords

gadolinium oxide; microwave-assisted; photodegradation; advanced oxidation process; polyethylene microplastics

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DOI: https://doi.org/10.22146/ijc.108052