Degradation of Methylene Blue via H₂O₂/HCO₃⁻/Co²⁺ System Using Cobalt Recovered from Spent Li-Ion Batteries

Degradation of Methylene Blue via H₂O₂/HCO₃⁻/Co²⁺ System Using Cobalt Recovered from Spent Li-Ion Batteries | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Degradation of Methylene Blue via H₂O₂/HCO₃⁻/Co²⁺ System Using Cobalt Recovered from Spent Li-Ion Batteries Eric M. Garcia, Hosane A. Taroco, Julio O.F Melo, Patrícia A. Rocha, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6505006/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract The increasing environmental burden posed by synthetic dyes and electronic waste demands innovative, sustainable solutions. In this work, we present a green and efficient advanced oxidation process (AOP) employing cobalt ions recovered from spent Li-ion battery (LIB) cathodes to catalyze the degradation of methylene blue (MB), a model organic pollutant. The Co²⁺/HCO₃⁻/H₂O₂ system enabled complete decolorization of a 10 ppm MB solution within 10 minutes under mild conditions (pH ~ 8.3), with kinetic analysis revealing pseudo-zero-order behavior in MB and half-order dependence on Co²⁺, HCO₃⁻, and H₂O₂. UV–Vis spectroscopy confirmed the formation of the [Co(CO₃)₃]³⁻ complex, while electrospray ionization mass spectrometry (ESI-MS) revealed demethylated intermediates and smaller fragments, suggesting progressive mineralization. Mechanistic insights indicate the predominant formation of carbonate radicals (•CO₃⁻), as supported by isopropanol scavenging experiments. This study highlights the dual environmental benefit of cobalt recovery and wastewater treatment, offering a sustainable pathway for the valorization of electronic waste and the mitigation of textile dye pollution. Li-ion battery recycling spent cathode methylene blue Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 31 May, 2025 Reviews received at journal 17 May, 2025 Reviews received at journal 12 May, 2025 Reviewers agreed at journal 08 May, 2025 Reviewers agreed at journal 05 May, 2025 Reviewers agreed at journal 04 May, 2025 Reviews received at journal 03 May, 2025 Reviewers agreed at journal 25 Apr, 2025 Reviewers invited by journal 24 Apr, 2025 Editor assigned by journal 22 Apr, 2025 Submission checks completed at journal 22 Apr, 2025 First submitted to journal 22 Apr, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6505006","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":446962443,"identity":"518a01e7-8d42-491c-988d-75bf738a3269","order_by":0,"name":"Eric M. 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In this work, we present a green and efficient advanced oxidation process (AOP) employing cobalt ions recovered from spent Li-ion battery (LIB) cathodes to catalyze the degradation of methylene blue (MB), a model organic pollutant. The Co\u0026sup2;⁺/HCO₃⁻/H₂O₂ system enabled complete decolorization of a 10 ppm MB solution within 10 minutes under mild conditions (pH\u0026thinsp;~\u0026thinsp;8.3), with kinetic analysis revealing pseudo-zero-order behavior in MB and half-order dependence on Co\u0026sup2;⁺, HCO₃⁻, and H₂O₂. UV\u0026ndash;Vis spectroscopy confirmed the formation of the [Co(CO₃)₃]\u0026sup3;⁻ complex, while electrospray ionization mass spectrometry (ESI-MS) revealed demethylated intermediates and smaller fragments, suggesting progressive mineralization. Mechanistic insights indicate the predominant formation of carbonate radicals (\u0026bull;CO₃⁻), as supported by isopropanol scavenging experiments. 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