CuO–ZnO/LTA Zeolite for Catalytic Ozonation of Methylene Blue: Calcination and DFT Insights
9 affiliations
- 1Département Génie des Procédés, Faculté des Sciences et Technologies, Université de Relizane, Relizane 48000, Algeria
- 2Laboratoire de Chimie des Matériaux L.C.M, Université Oran1 Ahmed Ben Bella, BP 1524, El Mnaouer, Oran 31000, Algeria
- 3Institut des Sciences Techniques et Appliquées (ISTA), Université Oran1 Ahmed Ben Bella, BP 1524, El-Mnaouer, Oran 31000, Algeria
- 4Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy
- 5Département de Chimie, Faculté des Sciences et Technologies, Université de Relizane, Relizane 48000, Algeria
- 6Département de Génie des Matériaux, Faculté de Chimie, Université des Sciences et de la Technologie Mohamed Boudiaf, BP 1505, El-Mnaouer, Oran 31000, Algeria
- 7Department of Physics, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- 8Faculty of Science and Technology, Ahmed Ben Yahia Al Wancharissi University, Tissemsilt 38000, Algeria
- 9Catalysis Research Group (CRG), Department of Chemistry, College of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
Abstract
In this work, LTA-type zeolite synthesized from kaolin was successfully modified via ion exchange with Zn2+ and Cu2+ ions followed by thermal treatment at 550 °C and 650 °C, leading to the formation of ZnO–CuO/zeolite composites (ZA550ZnCu and ZA650ZnCu). The structural and physicochemical properties of the catalysts were investigated using XRD, SEM, EDS, XPS, TEM, and zeta-potential analysis, confirming the successful incorporation of metal oxides while preserving the zeolitic framework, particularly at moderate calcination temperature. The catalytic performance of the prepared materials was evaluated in the heterogeneous catalytic ozonation of methylene blue (MB) in aqueous solution. The results demonstrated a strong synergistic effect between adsorption on the zeolite surface and ozone activation by ZnO and CuO species, leading to the generation of reactive oxygen species (•OH, O2•−) responsible for rapid methylene blue degradation. Among the tested catalysts, ZA550ZnCu exhibited superior activity compared to ZA650ZnCu, attributed to better dispersion of active phases and higher structural stability. Operational parameters, including pH, catalyst dosage, and initial MB concentration, significantly influenced the decolorization efficiency. Alkaline conditions (pH 11) strongly enhanced MB removal due to increased hydroxyl radical formation. Kinetic analysis showed that the degradation process follows a pseudo-first-order model, with higher rate constants in the presence of the catalyst. The electronic structure and local reactivity of methylene blue were investigated through DFT calculations and used to support the identification of potentially reactive sites and to propose plausible initial oxidation steps. The most reactive sites were identified as the dimethylamino nitrogen atoms, the central sulfur and nitrogen centers, and certain carbon atoms of the conjugated framework using frontier molecular orbital analysis, global reactivity descriptors, Hirshfeld charges, condensed Fukui functions, and the dual descriptor. These results are consistent with an initial N-demethylation, oxidative attack on the heterocyclic chromophore, C–N and C–S bond cleavage, hydroxylation, and aromatic-ring opening followed by mineralization. The study highlights the effectiveness of natural-source zeolite-based bimetallic catalysts as promising and sustainable materials for wastewater treatment via catalytic ozonation.
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BibTeX
@article{zerrouk2026cuoznolta,
title = {{CuO–ZnO/LTA Zeolite for Catalytic Ozonation of Methylene Blue: Calcination and DFT Insights}},
author = {Bekri Zerrouk and Adel Mokhtar and Soumia Abdelkrim and Gianluca Viscusi and Mohammed Hachemaoui and Bouhadjar Boukoussa and Mohamed Sassi and Shashikant P. Patole and Boubekeur Asli and Mohamed Abboud},
journal = {Catalysts},
year = {2026},
month = sep,
doi = {10.3390/catal16100879},
url = {https://www.mdpi.com/2073-4344/16/10/879},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - CuO–ZnO/LTA Zeolite for Catalytic Ozonation of Methylene Blue: Calcination and DFT Insights
AU - Bekri Zerrouk
AU - Adel Mokhtar
AU - Soumia Abdelkrim
AU - Gianluca Viscusi
AU - Mohammed Hachemaoui
AU - Bouhadjar Boukoussa
AU - Mohamed Sassi
AU - Shashikant P. Patole
AU - Boubekeur Asli
AU - Mohamed Abboud
PY - 2026
DA - 2026/09/30
JO - Catalysts
DO - 10.3390/catal16100879
UR - https://www.mdpi.com/2073-4344/16/10/879
AB - In this work, LTA-type zeolite synthesized from kaolin was successfully modified via ion exchange with Zn2+ and Cu2+ ions followed by thermal treatment at 550 °C and 650 °C, leading to the formation of ZnO–CuO/zeolite composites (ZA550ZnCu and ZA650ZnCu). The structural and physicochemical properties of the catalysts were investigated using XRD, SEM, EDS, XPS, TEM, and zeta-potential analysis, confirming the successful incorporation of metal oxides while preserving the zeolitic framework, particularly at moderate calcination temperature. The catalytic performance of the prepared materials was evaluated in the heterogeneous catalytic ozonation of methylene blue (MB) in aqueous solution. The results demonstrated a strong synergistic effect between adsorption on the zeolite surface and ozone activation by ZnO and CuO species, leading to the generation of reactive oxygen species (•OH, O2•−) responsible for rapid methylene blue degradation. Among the tested catalysts, ZA550ZnCu exhibited superior activity compared to ZA650ZnCu, attributed to better dispersion of active phases and higher structural stability. Operational parameters, including pH, catalyst dosage, and initial MB concentration, significantly influenced the decolorization efficiency. Alkaline conditions (pH 11) strongly enhanced MB removal due to increased hydroxyl radical formation. Kinetic analysis showed that the degradation process follows a pseudo-first-order model, with higher rate constants in the presence of the catalyst. The electronic structure and local reactivity of methylene blue were investigated through DFT calculations and used to support the identification of potentially reactive sites and to propose plausible initial oxidation steps. The most reactive sites were identified as the dimethylamino nitrogen atoms, the central sulfur and nitrogen centers, and certain carbon atoms of the conjugated framework using frontier molecular orbital analysis, global reactivity descriptors, Hirshfeld charges, condensed Fukui functions, and the dual descriptor. These results are consistent with an initial N-demethylation, oxidative attack on the heterocyclic chromophore, C–N and C–S bond cleavage, hydroxylation, and aromatic-ring opening followed by mineralization. The study highlights the effectiveness of natural-source zeolite-based bimetallic catalysts as promising and sustainable materials for wastewater treatment via catalytic ozonation.
SN - 2073-4344
ER -