Mechanistic Insights into the Oxidizing Reactivity of Birnessite from Electron Affinity

Mechanistic Insights into the Oxidizing Reactivity of Birnessite from Electron Affinity | 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 Mechanistic Insights into the Oxidizing Reactivity of Birnessite from Electron Affinity Adrian T. Wong, Eleanor J. Brooks, Noah M. Patel This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7874196/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Birnessite is a layered manganese oxide that acts as a strong oxidant, but the electronic reason for this behavior is not fully defined. We tested nine natural and synthetic birnessites with different interlayer cations and Mn(III)/Mn(IV) ratios to evaluate how electron affinity (EA) affects oxidation. Ultraviolet photoelectron spectroscopy, supported by density functional theory, gave EA values of 5.56–6.08 eV. Batch tests at pH 7.0 and 25 °C showed pseudo-second-order kinetics for Fe(II) and As(III) oxidation, with k2 rising from 7.5×10−4 to 3.4×10−3 g mg⁻¹ min⁻¹ for Fe(II) and from 4.1×10−4 to 2.1×10−3 g mg⁻¹ min⁻¹ for As(III); the k2–EA fit was exponential with R2=0.92. The apparent activation energy decreased from 48±3 to 29±2 kJ mol⁻¹ as EA increased. Post-reaction XPS showed less MnOOH on high-EA samples, which kept 82–88% of their initial activity after five cycles, compared with 52–60% for low-EA samples. These results show that electron affinity is a useful, quantitative factor for predicting oxidizing strength in birnessite and can guide the design of stable manganese oxide catalysts for pollutant removal. Environmental Engineering Environmental Policy birnessite electron affinity oxidation kinetics manganese oxides activation energy surface passivation environmental catalysis Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted 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-7874196","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":530438141,"identity":"457bd6ae-b8dd-44a0-893d-2f32491b608d","order_by":0,"name":"Adrian T. 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We tested nine natural and synthetic birnessites with different interlayer cations and Mn(III)/Mn(IV) ratios to evaluate how electron affinity (EA) affects oxidation. Ultraviolet photoelectron spectroscopy, supported by density functional theory, gave EA values of 5.56–6.08 eV. Batch tests at pH 7.0 and 25 °C showed pseudo-second-order kinetics for Fe(II) and As(III) oxidation, with k2 rising from 7.5×10−4 to 3.4×10−3 g mg⁻¹ min⁻¹ for Fe(II) and from 4.1×10−4 \u0026nbsp;to \u0026nbsp;2.1×10−3 g mg⁻¹ min⁻¹ for As(III); the k2–EA fit was exponential with R2=0.92. The apparent activation energy decreased from 48±3 to 29±2 kJ mol⁻¹ as EA increased. Post-reaction XPS showed less MnOOH on high-EA samples, which kept 82–88% of their initial activity after five cycles, compared with 52–60% for low-EA samples. These results show that electron affinity is a useful, quantitative factor for predicting oxidizing strength in birnessite and can guide the design of stable manganese oxide catalysts for pollutant removal.\u003c/p\u003e","manuscriptTitle":"Mechanistic Insights into the Oxidizing Reactivity of Birnessite from Electron Affinity","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 03:16:16","doi":"10.21203/rs.3.rs-7874196/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5cd138a5-4526-4494-888a-a1bd928502bb","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":56387566,"name":"Environmental Engineering"},{"id":56387567,"name":"Environmental Policy"}],"tags":[],"updatedAt":"2025-10-17T03:16:16+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-17 03:16:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7874196","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7874196","identity":"rs-7874196","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}