Green Synthesis and Physicochemical Characterization of Biogenic Silver Nanoparticles for Comparative Sunlight and Uv Photocatalytic Degradation of Congo Red

Green Synthesis and Physicochemical Characterization of Biogenic Silver Nanoparticles for Comparative Sunlight and Uv Photocatalytic Degradation of Congo Red | 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 Green Synthesis and Physicochemical Characterization of Biogenic Silver Nanoparticles for Comparative Sunlight and Uv Photocatalytic Degradation of Congo Red Aditya s, Vimal A, Kavipraba A This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8757702/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 17 You are reading this latest preprint version Abstract Silver nanoparticles (Ag NPs) were biosynthesized using Bacillus subtilis AVK-21 isolated from water samples, wherein microbial metabolites served as natural reducing and stabilizing agents for the reduction of Ag + to Ag 0 nanoparticles. The formation of Ag NPs was confirmed by a distinct SPR peak observed in UV-Vis spectroscopy at 430 nm, while FTIR analysis revealed functional biomolecules responsible for nanoparticle capping. SAED pattern depicts the crystalline face-centered cubic structure of the particles, and energy-dispersive X-ray spectroscopy (EDS) verified elemental silver with energy peak near 3keV. Transmission electron microscopy (TEM) demonstrated predominantly spherical nanoparticles with an average primary size of 62.4 nm, whereas dynamic light scattering (DLS) indicated a hydrodynamic diameter of 271.3 nm, reflecting the aggregation behavior of the biogenic Ag NPs. The zeta potential value was found to be 0.0 mV which further supported their limited colloidal stability and corresponded with the clustered morphology seen in TEM micrographs. The photocatalytic efficiency of the biosynthesized Ag NPs was evaluated using Congo Red dye under two conditions i.e., sunlight and UV light in which sunlight exposure resulted in significantly greater degradation (67.01%) compared to UV irradiation (37.80%) within 120 min. The enhanced effectiveness under sunlight is attributed to stronger plasmonic excitation and improved ROS generation, which facilitated electron transfer and the subsequent breakdown of the dye’s structure. Overall, this study demonstrates that microbially synthesized Ag NPs possess good photocatalytic potential and can efficiently degrade Congo Red under natural sunlight, highlighting their applicability as sustainable, low-energy catalysts for dye-polluted wastewater treatment. Bacillus subtilis AVK-21 Congo Red degradation Green synthesis Photocatalytic dye degradation Silver nanoparticles Full Text Additional Declarations No competing interests reported. Supplementary Files OnlineResource2.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 01 Mar, 2026 Reviews received at journal 28 Feb, 2026 Reviews received at journal 26 Feb, 2026 Reviewers agreed at journal 26 Feb, 2026 Reviewers agreed at journal 26 Feb, 2026 Reviewers agreed at journal 25 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers invited by journal 24 Feb, 2026 Editor assigned by journal 04 Feb, 2026 Submission checks completed at journal 04 Feb, 2026 First submitted to journal 01 Feb, 2026 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-8757702","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":596654669,"identity":"12088781-e175-4cda-aeed-88da52a1af30","order_by":0,"name":"Aditya s","email":"","orcid":"","institution":"Sathyabama Institute of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Aditya","middleName":"","lastName":"s","suffix":""},{"id":596654671,"identity":"4a623302-0562-4662-9dd2-fe9478935fc6","order_by":1,"name":"Vimal A","email":"","orcid":"","institution":"Sathyabama Institute of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Vimal","middleName":"","lastName":"A","suffix":""},{"id":596654672,"identity":"402687d8-403a-48a3-afda-62fe486d0788","order_by":2,"name":"Kavipraba A","email":"data:image/png;base64,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","orcid":"","institution":"Sathyabama Institute of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Kavipraba","middleName":"","lastName":"A","suffix":""}],"badges":[],"createdAt":"2026-02-01 16:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8757702/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8757702/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104397782,"identity":"cc15ee1a-e83f-4f92-8a65-16c17c349b96","added_by":"auto","created_at":"2026-03-11 11:56:24","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1447660,"visible":true,"origin":"","legend":"","description":"","filename":"Majorrevisionfinaldraft31.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8757702/v1_covered_ae2213d6-f486-4531-9ff9-83f2f9c13ce9.pdf"},{"id":103524403,"identity":"55da8343-d8d4-4153-976d-3d161026f752","added_by":"auto","created_at":"2026-02-26 15:41:51","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":9770288,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineResource2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8757702/v1/70657d5df2068e3c9399b5e8.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eGreen Synthesis and Physicochemical Characterization of Biogenic Silver Nanoparticles for Comparative Sunlight and Uv Photocatalytic Degradation of Congo Red\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nanotechnology-for-environmental-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ntee","sideBox":"Learn more about [Nanotechnology for Environmental Engineering](http://link.springer.com/journal/41204)","snPcode":"41204","submissionUrl":"https://submission.springernature.com/new-submission/41204/3","title":"Nanotechnology for Environmental Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Bacillus subtilis AVK-21, Congo Red degradation, Green synthesis, Photocatalytic dye degradation, Silver nanoparticles","lastPublishedDoi":"10.21203/rs.3.rs-8757702/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8757702/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSilver nanoparticles (Ag NPs) were biosynthesized using \u003cem\u003eBacillus subtilis\u003c/em\u003e AVK-21 isolated from water samples, wherein microbial metabolites served as natural reducing and stabilizing agents for the reduction of Ag\u003csup\u003e+\u003c/sup\u003e to Ag\u003csup\u003e0\u003c/sup\u003e nanoparticles. The formation of Ag NPs was confirmed by a distinct SPR peak observed in UV-Vis spectroscopy at 430 nm, while FTIR analysis revealed functional biomolecules responsible for nanoparticle capping. SAED pattern depicts the crystalline face-centered cubic structure of the particles, and energy-dispersive X-ray spectroscopy (EDS) verified elemental silver with energy peak near 3keV. Transmission electron microscopy (TEM) demonstrated predominantly spherical nanoparticles with an average primary size of 62.4 nm, whereas dynamic light scattering (DLS) indicated a hydrodynamic diameter of 271.3 nm, reflecting the aggregation behavior of the biogenic Ag NPs. The zeta potential value was found to be 0.0 mV which further supported their limited colloidal stability and corresponded with the clustered morphology seen in TEM micrographs. The photocatalytic efficiency of the biosynthesized Ag NPs was evaluated using Congo Red dye under two conditions i.e., sunlight and UV light in which sunlight exposure resulted in significantly greater degradation (67.01%) compared to UV irradiation (37.80%) within 120 min. The enhanced effectiveness under sunlight is attributed to stronger plasmonic excitation and improved ROS generation, which facilitated electron transfer and the subsequent breakdown of the dye\u0026rsquo;s structure. Overall, this study demonstrates that microbially synthesized Ag NPs possess good photocatalytic potential and can efficiently degrade Congo Red under natural sunlight, highlighting their applicability as sustainable, low-energy catalysts for dye-polluted wastewater treatment.\u003c/p\u003e","manuscriptTitle":"Green Synthesis and Physicochemical Characterization of Biogenic Silver Nanoparticles for Comparative Sunlight and Uv Photocatalytic Degradation of Congo Red","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-26 15:41:43","doi":"10.21203/rs.3.rs-8757702/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-01T12:12:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-28T13:42:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-27T03:26:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"287957403170309664168665052412835608600","date":"2026-02-26T11:20:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"20287081973406042589159498993807128254","date":"2026-02-26T05:15:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6889430612180026881123783277584083246","date":"2026-02-26T01:30:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"294539316067205088677810019988099538309","date":"2026-02-25T04:28:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"15248823759990293992798604894674699694","date":"2026-02-24T22:17:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"232144242225997440147810289609022669009","date":"2026-02-24T19:50:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"279620823340191019341113919021626333691","date":"2026-02-24T12:02:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"90571019330758458122181245354537115483","date":"2026-02-24T11:47:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"97464623188782311042488916048215261767","date":"2026-02-24T11:34:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"260252436885146401941748827354243380978","date":"2026-02-24T11:24:17+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-24T11:00:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-04T19:48:47+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-04T19:46:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Nanotechnology for Environmental Engineering","date":"2026-02-01T16:20:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nanotechnology-for-environmental-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ntee","sideBox":"Learn more about [Nanotechnology for Environmental Engineering](http://link.springer.com/journal/41204)","snPcode":"41204","submissionUrl":"https://submission.springernature.com/new-submission/41204/3","title":"Nanotechnology for Environmental Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"558e56c9-4201-4a4b-ade1-b60baff0e5d7","owner":[],"postedDate":"February 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-01T14:08:48+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-26 15:41:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8757702","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8757702","identity":"rs-8757702","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}