Evaluation of basalt powder as a natural heterogeneous catalyst in photo-Fenton like treatment of atrazine

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2024-01, Vol.446, p.115149, Article 115149
• Main Authors: Carmelo da Rocha, Amanda, de Oliveira Sampaio Dantas, Ádila, Angélica Vieira, Patrícia, Luiz Cardoso, Vicelma
• Format: Article
• Language: English
• Subjects: By-products; Circumneutral pH; Clay catalyst; Photo-Fenton like; Scavenger
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2023.115149

[Display omitted] •At circumneutral pH photo-Fenton like promoted atrazine oxidation by basalt powder.•The promoted activity was attributed to iron redox cycle in basalt surface.•The efficiency under UV-C irradiation not decreased after three reusability cycles.•After photo-Fenton like processes low toxicity was observed. Basalt powder was employed to degrade atrazine (ATZ) under ultra-violet (UV-C) and visible light (vis) irradiation. The characterization of clay catalyst samples was confirmed the presence of ferrous oxide responsible of the heterogeneous photo-Fenton like reactions. Initial tests, using an ATZ concentration of 20 mg L−1 and raw basalt (B-R) form, validated the photo-Fenton like process as the most efficient. The optimal conditions were identified to be: an initial pH of approximately 6, basalt sintered at 600 °C (B-600) with dosage of 0.5 g L−1 under UV-C and 0.75 g L−1 under vis, and initial H2O2 concentration of 1.6 mM. Consequently, ATZ removal (initially at 5 mg L−1) was measured at 96.0% and 55.8% under UV-C and vis light, respectively, after 180 min of irradiation, with reusability of three cycles. The efficiency of the photo-Fenton process was further investigated by monitoring the toxicity bioassays of growth bacteria inhibition and phytotoxicity of the treated solutions. The results indicated that, under both UV and Vis irradiation, even with high ATZ removal efficiency, the toxicity of the process effluent is less than the initial sample. The initial degradation products were determined by high performance liquid chromatography (HPLC), and ATZ degradation pathway in the photo-Fenton like system was proposed, in which the reaction is primarily initiated by alkylic oxidation. Finally, the reaction’s inhibition upon addition of isopropanol and chloroform as scavengers emphasized the significant role of hydroxyl radicals over superoxide in the oxidation of ATZ.