Int. J. Renew. Energy Dev. 2023, 12(3), 508-519 | 508 https://doi.org/10.14710/ijred.2023.52044 ISSN: 2252-4940/© 2023.The Author(s). Published by CBIORE Contents list available at IJRED website International Journal of Renewable Energy Development Journal homepage: https://ijred.undip.ac.id Removal efficiency and reaction kinetics of phenolic compounds in refinery wastewater by nano catalytic wet oxidation Yousif S. Issa 1 , Khaleel I. Hamad 2 , Rafi J. Algawi 1 , Jasim I. Humadi 1* , Sara Al-Salihi 3 , Mustafa A. Ahmed 4 , Ahmed A. Hassan 5 , Abdul-Kareem Abd Jasim 6 1 Department of Petroleum and Gas Refining Engineering, College of Petroleum Processes Engineering, Tikrit University, Iraq 2 Slah Al-Deen, General Directorate of Education, Iraq 3 Department of Biomedical, Biological & Chemical Engineering, University of Missouri, Columbia, 65211, United States 4 Ministry of Oil, Baghdad, Iraq 5 North Refineries Company, Baji Refineries, Ministry of Oil, Iraq 6 Oil Products Distribution Company, Salahaddin Branch Ministry of Oil, Iraq Abstract. A novel nano-catalyst based on iron oxide (MnO2/Fe2O3) was developed to promote wet oxidation of phenol. MnO2 was doped in Fe2O3 matrix to prepare composite nano-catalyst with different doping percentage (0, 2 and 5%). The catalytic phenol oxidation was conducted under different reaction temperatures and residence times. To evaluate the optimal kinetic parameters aiming to maximize phenol removal under the optimal conditions for the catalytic wet phenol oxidation process, modeling was applied on the batch reactor using the novel synthesis nano-catalyst (MnO2/Fe2O3) and the model developed was fed with the experimental data. gPROMS package was used to model the process of phenol oxidation and to optimize the experimental data. The error predicted between the simulated and experimental data was less than 5%. The optimal operating conditions were 294 min residence time, 70 o C reaction temperature, and 764 ppm initial concentration of phenol over the prepared 5% MnO2/Fe2O3. Running of wet oxidation of phenol under the optimal operating conditions resulted in 98% removal of phenol from refinery wastewater. Keywords: Nano-catalyst; manganese oxide/ iron oxide; phenol; oxidation process; optimization @ The author(s). Published by CBIORE. This is an open access article under the CC BY-SA license (http://creativecommons.org/licenses/by-sa/4.0/). Received: 24 th January 2023; Revised: 5 th March 2023; Accepted: 30 th March 2023; Available online: 11 th April 2023 1. Introduction The water contamination by organic compounds is considered as a threat to the health of human and overall quality of water since the wastewater is predominating released from industrial plants without any efficient treatment. Phenol and phenolic compounds are considered a priority pollutant contaminant categorized as teratogenicity and carcinogenic (Saravanan et al., 2021; Stefanakis & Thullner, 2016; Wang, Bian, & Li, 2012; Yaqub, Isa, Ajab, & Junaid, 2017). Different technologies, such as electrochemical degradation (Iniesta, González-Garcıa, Exposito, Montiel, & Aldaz, 2001; Li, Cui, Feng, Xie, & Gu, 2005; Luo, Li, Wu, Zheng, & Dong, 2015), biodegradation (Amor, Eiroa, Kennes, & Veiga, 2005; Kumar, Kumar, & Kumar, 2005; Peyton, Wilson, & Yonge, 2002), physical sorption (Hamad et al., 2022b; Humadi et al., 2022; Li et al., 2002; Pan et al., 2003), and the advanced oxidation Processes (AOPs) (Amor et al., 2019; Aziz, Asaithambi, & Daud, 2016; Esplugas, Gimenez, Contreras, Pascual, & Rodrı́guez, 2002; Hamad et al., 2022b; Martins & Quinta-Ferreira, 2011; Xu, Siracusa, Di Gregorio, & Yuan, 2018) have been employed to purify the wastewater. The advanced oxidation processes (AOPs) are characterized by producing highly reactive oxidizing radicals, can degrade these organic * Corresponding author Email: jasim_alhashimi_ppe@tu.edu.iq (J.I.Humadi) contaminants to carbon dioxide, water, and mineral salts (mineralization) (Covinich, Bengoechea, Fenoglio, & Area, 2014; Gągol et al., 2020; Lozano, Devard, Ulla, & Zamaro, 2020; Shahidi, Roy, & Azzouz, 2015). AOPs processes include treatment with UV/H2O2, ozonation, photocatalysis, air wet oxidation and catalytic wet peroxide oxidation (CWPO). Hydrogen peroxide (H2O2) is a green oxidant has the ability to work in the CWPO at moderate operating conditions (atmospheric pressure, T<80 °C) (Busca, Berardinelli, Resini, & Arrighi, 2008; Martin-Martinez et al., 2016; Piccinin, 2022; Shahidi et al., 2015). Also, hydrogen peroxide is utilized as liquid oxidant in CWPO to overcome the gas–liquid mass transfer limitations and significantly enhance the efficiency of process. CWPO is superior to other AOPs technologies because it provides lower activation energy by utilizing a catalyst to enable the reaction to proceed under mild operating conditions (Baloyi, Ntho, & Moma, 2018; Wang et al., 2021; Yan, Wu, & Zhang, 2016). Recently, there is a growing attention in the use of iron oxide nanoparticles for the removal of heavy metal found in wastewater owing to their availability and simplicity. In general, due to the small size of Nano sorbent materials, their separation and recovery from contaminated water is an important issue for Research Article