{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T05:14:18Z","timestamp":1783401258162,"version":"3.54.6"},"reference-count":41,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T00:00:00Z","timestamp":1782691200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Chlorpyrifos, a widely used organophosphate pesticide, poses significant environmental risks due to its persistence and the formation of toxic transformation products. Despite extensive research on iron-based Fenton systems, the application of manganese oxides, particularly \u03b1-Mn2O3, in chlorpyrifos degradation remains insufficiently explored. In this study, we investigated the catalytic performance of \u03b1-Mn2O3 in Fenton and visible-light-driven photo-Fenton processes for the degradation of chlorpyrifos in aqueous systems. Chlorpyrifos oxon was identified as a transient intermediate, detected at trace levels, supporting an oxidative degradation pathway. Kinetic analysis revealed pseudo-first-order behavior, with comparable rate constants for Fenton reactions at different catalyst loadings (0.0033 min\u22121 for 5 mg and 0.0028 \u00b1 0.0006 min\u22121 for 10 mg), indicating that the process is not limited by catalyst concentration under the investigated conditions. In contrast, the photo-Fenton system exhibited a higher rate constant (0.0042 min\u22121) and significantly improved degradation efficiency, highlighting the role of visible-light activation. The highest removal rates of chlorpyrifos were 86.24% for Fenton experiments and 96.05% for the photo-Fenton experiment, respectively. The enhanced performance is attributed to the photocatalytic properties of \u03b1-Mn2O3, including its narrow bandgap and the facilitation of Mn3+\/Mn2+ redox cycling, which promotes reactive oxygen species generation. These findings demonstrate that \u03b1-Mn2O3 is a promising non-iron catalyst for advanced oxidation processes and provide new insights into manganese-mediated Fenton-like mechanisms for the removal of organophosphate contaminants.<\/jats:p>","DOI":"10.3390\/ijms27135856","type":"journal-article","created":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:55:11Z","timestamp":1782780911000},"page":"5856","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Fenton and Photo-Fenton Degradation of Chlorpyrifos Using \u03b1-Mn2O3 Heterogeneous Catalysis"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8936-4497","authenticated-orcid":false,"given":"Silviu-Laurentiu","family":"Badea","sequence":"first","affiliation":[{"name":"Research Center for Studies of Food Quality and Agricultural Products, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Marasti Blvd., 011464 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0439-3265","authenticated-orcid":false,"given":"Violeta-Carolina","family":"Niculescu","sequence":"additional","affiliation":[{"name":"National Research and Development Institute for Cryogenic and Isotopic Technologies\u2014ICSI Rm. V\u00e2lcea, 4th Uzinei Street, 240050 Ramnicu V\u00e2lcea, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marian-Nicolae","family":"Verziu","sequence":"additional","affiliation":[{"name":"Department of Bioresources and Polymer Science, National Research Center for Micro and Nanomaterials, National University of Science and Technology Politehnica Bucharest, 313 Spl. Independen\u021bei, 060042 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-8922-5561","authenticated-orcid":false,"given":"Teodor-Adi","family":"Ene","sequence":"additional","affiliation":[{"name":"National Research and Development Institute for Cryogenic and Isotopic Technologies\u2014ICSI Rm. V\u00e2lcea, 4th Uzinei Street, 240050 Ramnicu V\u00e2lcea, Romania"},{"name":"Department of Materials Science and Engineering, Faculty of Materials and Environmental Engineering, Technical University of Cluj-Napoca, 400641 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1819-5128","authenticated-orcid":false,"given":"Liliana-Aurelia","family":"Badulescu","sequence":"additional","affiliation":[{"name":"Research Center for Studies of Food Quality and Agricultural Products, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Marasti Blvd., 011464 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"108923","DOI":"10.1016\/j.cbpc.2020.108923","article-title":"Mixed toxicity of chlorpyrifos and dichlorvos show antagonistic effects in the endangered fish species golden mahseer (Tor putitora)","volume":"240","author":"Kunwar","year":"2021","journal-title":"Comp. Biochem. Physiol. Part C Toxicol. Pharmacol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"165","DOI":"10.17930\/AGL2020220","article-title":"Application effects of chlorpyrifos-ethyl and malathion on the lichen Xanthoria Parietina and the moss Funaria hygrometrica","volume":"9","author":"Mazari","year":"2020","journal-title":"AgroLife Sci. J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"110731","DOI":"10.1016\/j.ecoenv.2020.110731","article-title":"Ecotoxicity of chlorpyrifos to aquatic organisms: A review","volume":"200","author":"Huang","year":"2020","journal-title":"Ecotoxicol. Environ. Saf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1080\/03601234.2016.1270683","article-title":"Dissipation, half-lives, and mass spectrometric identification of chlorpyrifos and its two metabolites on field-grown collard and kale","volume":"52","author":"Antonious","year":"2017","journal-title":"J. Environ. Sci. Health Part B"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1016\/j.chemosphere.2017.08.156","article-title":"Environmental relevant concentrations of a chlorpyrifos commercial formulation affect two neotropical fish species, Cheirodon interruptus and Cnesterodon decemmaculatus","volume":"188","author":"Bonifacio","year":"2017","journal-title":"Chemosphere"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1007\/s10311-012-0392-0","article-title":"Chlorpyrifos insecticide uptake by plantain from polluted water and soil","volume":"11","author":"Romeh","year":"2013","journal-title":"Environ. Chem. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1002\/etc.5620220204","article-title":"Abiotic transformation of chlorpyrifos to chlorpyrifos oxon in chlorinated water","volume":"22","author":"Wu","year":"2003","journal-title":"Environ. Toxicol. Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/j.jhazmat.2014.04.054","article-title":"Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes","volume":"275","author":"Bokare","year":"2014","journal-title":"J. Hazard. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1249","DOI":"10.1007\/s40201-021-00674-1","article-title":"Advanced oxidation processes for chlorpyrifos removal from aqueous solution: A systematic review","volume":"19","author":"Sheikhi","year":"2021","journal-title":"J. Environ. Health Sci. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"119032","DOI":"10.1016\/j.jclepro.2019.119032","article-title":"Nano zerovalent zinc catalyzed peroxymonosulfate based advanced oxidation technologies for treatment of chlorpyrifos in aqueous solution: A semi-pilot scale study","volume":"246","author":"Shah","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"e30402","DOI":"10.1016\/j.heliyon.2024.e30402","article-title":"Advanced oxidation processes for water and wastewater treatment\u2014Guidance for systematic future research","volume":"10","author":"Spahr","year":"2024","journal-title":"Heliyon"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"100190","DOI":"10.1016\/j.actphy.2025.100190","article-title":"Interfacial engineering of Cd0.5Zn0.5S\/BiOBr S-scheme heterojunction with oxygen vacancies for effective photocatalytic antibiotic removal","volume":"41","author":"Ma","year":"2025","journal-title":"Acta Phys. Chim. Sin."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.jmst.2025.05.011","article-title":"Manipulating interfacial charge redistribution in Mn0.5Cd0.5S\/N-rich C3N5 S-scheme heterojunction for high-performance photocatalytic removal of emerging contaminants","volume":"243","author":"Ma","year":"2026","journal-title":"J. Mater. Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Silva, J.A. (2025). Advanced Oxidation Process in the Sustainable Treatment of Refractory Wastewater: A Systematic Literature Review. Sustainability, 17.","DOI":"10.3390\/su17083439"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1007\/s11270-009-0065-1","article-title":"Advanced Oxidation Processes for Wastewater Treatment: State of the Art","volume":"205","author":"Poyatos","year":"2010","journal-title":"Water Air Soil Pollut."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"195","DOI":"10.2166\/wrd.2015.062","article-title":"Advanced oxidation processes for the treatment of chlorpyrifos, dimethoate and phorate in aqueous solution","volume":"6","author":"Gandhi","year":"2015","journal-title":"J. Water Reuse Desalin."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"407","DOI":"10.3923\/jest.2012.407.418","article-title":"Fenton Treatment of Chlorpyrifos, Cypermethrin and Chlorothalonil Pesticides in Aqueous Solution","volume":"5","author":"Affam","year":"2012","journal-title":"J. Environ. Sci. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2952","DOI":"10.1016\/j.jece.2016.06.003","article-title":"Optimization of chlorpyrifos degradation by Fenton oxidation using CCD and ANFIS computing technique","volume":"4","author":"Saini","year":"2016","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Ameta, S.C., and Ameta, R. (2018). Chapter 3\u2014Fenton and Photo-Fenton Processes. Advanced Oxidation Processes for Waste Water Treatment, Academic Press.","DOI":"10.1016\/B978-0-12-810499-6.00003-6"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.2166\/ws.2010.777","article-title":"Degradation of chlorpyriphos in water by advanced oxidation processes","volume":"10","author":"Murillo","year":"2010","journal-title":"Water Supply"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/j.jiec.2024.08.006","article-title":"Metal oxides for Fenton reactions toward radical-assisted water treatment: A review","volume":"142","author":"Choe","year":"2025","journal-title":"J. Ind. Eng. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Jia, D., Hanna, K., Mailhot, G., and Brigante, M. (2021). A Review of Manganese(III) (Oxyhydr)Oxides Use in Advanced Oxidation Processes. Molecules, 26.","DOI":"10.3390\/molecules26195748"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"24465","DOI":"10.1039\/D6RA00930A","article-title":"Contrasting mechanisms of UDMH degradation by MnO2 and Mn2O3 under microwave assistance: Electronic structure, surface adsorption and catalytic reaction pathways","volume":"16","author":"Wang","year":"2026","journal-title":"RSC Adv."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"360","DOI":"10.1016\/j.electacta.2013.06.001","article-title":"Synthesis of Mn2O3 microstructures and their energy storage ability studies","volume":"106","author":"Chen","year":"2013","journal-title":"Electrochim. Acta"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2739","DOI":"10.1007\/s10854-016-5853-y","article-title":"A study of optical, surface morphological and electrical properties of manganese oxide nanoparticles","volume":"28","author":"Vijayamari","year":"2017","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"20240039","DOI":"10.1515\/chem-2024-0039","article-title":"One-pot synthesis of a network of Mn2O3\u2013MnO2\u2013poly(m-methylaniline) composite nanorods on a polypyrrole film presents a promising and efficient optoelectronic and solar cell device","volume":"22","author":"Aldosari","year":"2024","journal-title":"Open Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"101003","DOI":"10.1016\/j.cscee.2024.101003","article-title":"Rapid sustainable synthesis of Mn2O3, CuO, and binary CuO\/Mn2O3 nanoparticles using continuous laser diode for enhanced antibacterial strategy against resistant pathogens","volume":"10","author":"Anber","year":"2024","journal-title":"Case Stud. Chem. Environ. Eng."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1007\/s00339-025-08790-7","article-title":"Green-mediated synthesis of bixbyite \u03b1-Mn2O3 nanoparticles via Moringa oleifera: Impact of calcination on properties and visible-light photocatalytic degradation of Eosin yellow and eriochrome black T dyes","volume":"131","author":"Archana","year":"2025","journal-title":"Appl. Phys. A"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1016\/S1386-1425(03)00279-8","article-title":"Lattice vibrations of manganese oxides: Part I. Periodic structures","volume":"60","author":"Julien","year":"2004","journal-title":"Spectrochim. Acta Part A Mol. Biomol. Spectrosc."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Soulamidis, G., Stouraiti, C., Kourmousi, M., Tzevelekidis, P., Charalampous, E., and Mitsopoulou, C.A. (2023). Structural and Electrochemical Characterization of Natural Manganese Oxides for Energy Storage Applications. Mater. Proc., 15.","DOI":"10.3390\/materproc2023015064"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0079-6786(97)81003-5","article-title":"Manganese oxides for lithium batteries","volume":"25","author":"Thackeray","year":"1997","journal-title":"Prog. Solid State Chem."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Karako\u00e7, T., Sall, S., and Pronkin, S.N. (2025). Temperature-Dependent FTIRS Study of Manganese Oxide Spinel Obtained by Solution Combustion Synthesis (SCS) for Supercapacitor Applications. Batteries, 11.","DOI":"10.3390\/batteries11020039"},{"key":"ref_33","unstructured":"Monforte Ferrario, A. (2022). Characterization of Manganese Oxides Thin Films. [Master\u2019s Thesis, Politecnico di Milano]. Available online: https:\/\/www.politesi.polimi.it\/retrieve\/99ac87ac-e45d-4fae-a800\u201353314b8d8968\/2022_12_MonforteFerrario_Tesi.pdf."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"100665","DOI":"10.1016\/j.ceja.2024.100665","article-title":"Low-valent manganese active sites: Insight into reinforced interaction with sulfonated anthraquinone dye and kinetic adsorption studies over iron-modified cryptomelane","volume":"20","author":"Le","year":"2024","journal-title":"Chem. Eng. J. Adv."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Son, Y.-H., Bui, P.T.M., Lee, H.-R., Akhtar, M.S., Shah, D.K., and Yang, O.-B. (2019). A Rapid Synthesis of Mesoporous Mn2O3 Nanoparticles for Supercapacitor Applications. Coatings, 9.","DOI":"10.3390\/coatings9100631"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"6908","DOI":"10.1021\/acs.iecr.3c00196","article-title":"Tailoring Oxygen Vacancies and Active Surface Oxygen Species in Copper-Doped MnO2 Catalysts for Total Catalytic Oxidation of VOCs","volume":"62","author":"Nguyen","year":"2023","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/j.jhazmat.2017.12.028","article-title":"Chlorpyrifos degradation via photoreactive TiO2 nanoparticles: Assessing the impact of a multi-component degradation scenario","volume":"372","author":"Cooper","year":"2019","journal-title":"J. Hazard. Mater."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"121115","DOI":"10.1016\/j.jece.2026.121115","article-title":"Solar-driven photo-Fenton degradation of chlorpyrifos by silica sand-supported dual metal doped nano-titania and graphene oxide conjugate","volume":"14","author":"Mondal","year":"2026","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"6755","DOI":"10.1038\/s41598-024-56666-2","article-title":"Green synthesis and characterization of \u03b1-Mn2O3 nanoparticles for antibacterial activity and efficient visible-light photocatalysis","volume":"14","author":"Moradnia","year":"2024","journal-title":"Sci. Rep."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"805","DOI":"10.1016\/j.cej.2018.07.163","article-title":"Visible-light-driven photocatalytic degradation of ciprofloxacin by a ternary Mn2O3\/Mn3O4\/MnO2 valence state heterojunction","volume":"353","author":"Zhao","year":"2018","journal-title":"Chem. Eng. J."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1016\/j.jcis.2022.12.008","article-title":"Dual redox cycles of Mn(II)\/Mn(III) and Mn(III)\/Mn(IV) on porous Mn\/N co-doped biochar surfaces for promoting peroxymonosulfate activation and ciprofloxacin degradation","volume":"634","author":"Liu","year":"2023","journal-title":"J. Colloid Interface Sci."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/13\/5856\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T04:18:53Z","timestamp":1783397933000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/13\/5856"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,29]]},"references-count":41,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["ijms27135856"],"URL":"https:\/\/doi.org\/10.3390\/ijms27135856","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,29]]}}}