Global NEST Journal, Vol 26, No 1, 05312 Copyright© 2024 Global NEST Printed in Greece. All rights reserved Ahmed Halfadji, Mohamed Naous, Khaldia nadia Kharroubi, Fatima el zahraà Belmehdi and Hanane Aoudia (2024), Facile prepared Fe3O4 nanoparticles as a nano-catalyst on photo-fenton process to remediation of methylene blue dye from water: characterisation and optimization, Global NEST Journal, 26(1), 05312. Facile prepared Fe 3 O 4 nanoparticles as a nano-catalyst on photo- fenton process to remediation of methylene blue dye from water: characterisation and optimization Ahmed Halfadji 1,2, *, Mohamed Naous 2 , Khaldia nadia Kharroubi 3 , Fatima el zahraà Belmehdi 3 and Hanane Aoudia 2 1 Synthesis and Catalysis Laboratory, Ibn Khaldoun University of Tiaret, Tiaret, 14000, Algeria 2 Department of Sciences and Technology, Faculty of Applied Sciences, Ibn Khaldoun University of Tiaret, Tiare, 14000, Algeria 3 Departement of Chemistry, Ibn Khaldoun University of Tiaret, Tiaret, 14000, Algeria Received: 20/08/2023, Accepted: 31/10/2023, Available online: 07/11/2023 *to whom all correspondence should be addressed: e-mail: ahmedhalfadji@gmail.com https://doi.org/10.30955/gnj.005312 Graphical abstract Abstract In this research, a simple method for the preparation of Fe3O4 nanoparticles (Fe3O4NPs) with an average size of 38.05 nm via co-precipitation was investigated. X-ray diffraction (DRX), scanning electron microscopy (SEM), and infrared spectroscopy (FT-IR) were used to characterize obtained Fe3O4 nanoparticles. These Fe3O4NPs were then used as nano-catalysts to degrade Methylene Blue (MB) in an aqueous solution via the Photo Fenton-like process. Also, under room solar light and low temperature, the photocatalytic activity of Fe3O4NPs for degrading MB was optimized through various experimental factors such as pH (ranging from 2 to 8), H2O2 concentration (from 10 -2 to 5 × 10 -1 M), catalyst amount (20 to 60 mg), and target organic compound concentrations (10 to 40 mg/L). The optimal experimental conditions were found to be a pH of 3, H2O2 (0.5M), a dye concentration of 40 mg/L, and 40 mg of Fe3O4NPs as nano-catalyst. These conditions led to a high degree of removal (>86%) of MB dye from water. The pseudo- second-order kinetic model was the suitable model to describe the degradation of MB dye with a coefficient value of 0.969. From this, it was concluded that Fe3O4NPs could act as an effective nano-catalyst for a sustainable and environmentally friendly way to eliminate organic pollutants in water and wastewater. Keywords: Fe3O4Nps, structural characterization, MB degradation, photo-fenton oxidation process, pseudo- first-order model, nanocatalyst. 1. Introduction Contamination of water with organic pollutants is a significant environmental problem that has negative impacts on both ecosystems and humans. Chemicals such as pesticides, herbicides, petroleum, and dyes are often released into water and wastewater through industrial and agricultural practices (Chowdhary et al. 2020). Organic pollutants are harmful to aquatic life, the food chain, and water quality. They can also cause health problems for humans, such as cancer and neurological damage (Okoye et al. 2022). Therefore, the treatment of organic contaminated water and wastewater is crucial. Additionally, water scarcity due to drought has been a global issue in recent years. Thus, reusing treated wastewater is an effective approach to conserving freshwater resources (Manikandan et al. 2022). However, before releasing wastewater into the environment or using it for human consumption or agricultural irrigation, it must undergo treatment using methods such as filtration, bioremediation, and chemical treatments (Kesari et al. 2021). These methods aim to remove or degrade pollutants to ensure human safety and maintain the health and sustainability of the ecosystem (Kesari et al. 2021). Industrial activities are a significant source of organic pollutants. The textile industry, in particular, uses numerous organic compounds and dyes, which are discharged as effluent during dyeing and finishing processes. These organic dyes have low biodegradability, thus leading to the long-term pollution of water sources (Kesari et al. 2021). This contamination poses a threat to ecosystems and human health.