Microwave-assisted starch stabilization & Chitosan green synthesis of zinc oxide nanoparticles for the photocatalytic applications

Microwave-assisted starch stabilization & Chitosan green synthesis of zinc oxide nanoparticles for the photocatalytic applications | 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 Microwave-assisted starch stabilization & Chitosan green synthesis of zinc oxide nanoparticles for the photocatalytic applications Martin Ouma Osemba This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9131972/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 Zinc oxide (ZnO) nanoparticles were successfully synthesized via a microwave-assisted green route employing starch as a stabilizing matrix and chitosan as a biopolymeric capping and surface-functionalizing agent. Glucose served as a mild reducing agent, while microwave irradiation provided rapid and energy-efficient heating. The synthesis strategy aligns with green chemistry principles by minimizing hazardous reagents, reducing reaction time, and enabling controlled nanoparticle growth. UV–Vis spectroscopy revealed a characteristic excitonic absorption peak at 373 nm, confirming nanoscale ZnO formation. The optical band gap estimated from the Tauc plot was approximately 3.26 eV, indicating slight quantum confinement effects. FT-IR analysis showed a distinct Zn–O stretching vibration at 476.52 cm⁻¹ along with residual –OH and –NH₂ surface groups derived from starch and chitosan. XRD patterns confirmed the formation of phase-pure hexagonal wurtzite ZnO with an average crystallite size of 18–25 nm. SEM and TEM analyses revealed near-spherical nanoparticles with moderate aggregation, while EDX confirmed stoichiometric Zn and O composition with minor carbon and nitrogen contributions from surface biopolymers. Photocatalytic performance was evaluated using methylene blue (MB) under natural sunlight irradiation. The ZnO nanoparticles achieved over 90% degradation within 90 minutes and followed pseudo-first-order kinetics with an apparent rate constant of 0.024 min⁻¹. The enhanced photocatalytic activity is attributed to efficient charge carrier generation, suppressed electron–hole recombination mediated by surface functional groups, and increased reactive oxygen species (ROS) formation. The results demonstrate that microwave-assisted starch–chitosan stabilization offers a sustainable and scalable strategy for producing high-performance ZnO photocatalysts suitable for environmental remediation applications. Analytical Chemistry Biopolymers Polymer Science Nanoscience Photonics/optics Environmental Engineering Environmental Chemistry Zinc oxide nanoparticles Microwave synthesis green chemistry Photocatalysis Methylene blue degradation 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-9131972","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":606520230,"identity":"9ee9713d-959d-4522-8409-1f3bbc4b6d62","order_by":0,"name":"Martin Ouma Osemba","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCklEQVRIiWNgGAWjYNCCCgh1AEKxQSgJvFrOwLQkEKuFsQ3GIkaLbnuP6Yaf8+zs5dubHx74+cPGnkHsWJoEQ40dg2R7A1YtZmfOmN3s3ZacuOHMMYODPQlpiQ3SacckGI4lM0jzHMCu5UaO2Q3ebcwJBhI5DAd4Eg4nMEint0kwsB1gkJNIwKnl5t859fbyM3IYDv5J+G8P0fIPqEX+AU4tt3kbDjM23MhhOMyTcIAR7DDGtgMM0jj8b3bmWNltmWPHwX45LJOWnNgmnZZskdiXzCPZg8Nhx5u33XxTUw0Ksccf39jY2fNLpxne+PDNTk7iOHbvYwJwrADN5yFS/SgYBaNgFIwCLAAAyTFdk+mKoW0AAAAASUVORK5CYII=","orcid":"https://orcid.org/0009-0007-2045-4746","institution":"Mount Kenya University","correspondingAuthor":true,"prefix":"","firstName":"Martin","middleName":"Ouma","lastName":"Osemba","suffix":""}],"badges":[],"createdAt":"2026-03-16 02:00:03","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":true,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":true},"doi":"10.21203/rs.3.rs-9131972/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9131972/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104783426,"identity":"bd739e25-83e1-4d88-ba19-d39d5c6c843b","added_by":"auto","created_at":"2026-03-17 07:58:56","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":867604,"visible":true,"origin":"","legend":"","description":"","filename":"Microwaveassistedstarchstabilizedgreensynthesisofzincoxidenanoparticlesforphotocatalyticapplications.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9131972/v1_covered_9000c497-e513-4e53-8725-a4f8d5e729b2.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eMicrowave-assisted starch stabilization \u0026amp; Chitosan green synthesis of zinc oxide nanoparticles for the photocatalytic applications\u003c/strong\u003e\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Mount Kenya University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"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},"keywords":"Zinc oxide nanoparticles, Microwave synthesis, green chemistry, Photocatalysis, Methylene blue degradation","lastPublishedDoi":"10.21203/rs.3.rs-9131972/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9131972/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eZinc oxide (ZnO) nanoparticles were successfully synthesized via a microwave-assisted green route employing starch as a stabilizing matrix and chitosan as a biopolymeric capping and surface-functionalizing agent. 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