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Formation and characterization of mechanochemically generated free lignin radicals from olive seeds

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In this study, formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer, structural changes were followed by XRD and FTIR-ATR; thermal stabilities were tracked by TGA and DSC. | Turkish Journal of Chemistry Turk J Chem 2021 45 282-294 http journals.tubitak.gov.tr chem TÜBİTAK Research Article doi 10.3906 kim-2008-19 Formation and characterization of mechanochemically generated free lignin radicals from olive seeds Fatma DEMİR Department of Chemistry Faculty of Science Bilkent University Ankara Turkey Received 13.08.2020 Accepted Published Online 04.11.2020 Final Version 28.04.2021 Abstract In this study formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer structural changes were followed by XRD and FTIR-ATR thermal stabilities were tracked by TGA and DSC. In order to enable solubility demanding studies such as 1H NMR and GPC acylation of lignin was accomplished. ESR measurements were completed to prove the nature of the radicals. Free radicals cavenging activity of olive seed lignin was determined and quantified using 2-diphenyl-1-picrylhydrazyl DPPH method. Number of created mechanoradicals per gram of olive seed lignin was calculated from the corresponding UV Vis spectra. Finally morphological changes of the lignin over cryomilling was evaluated using SEM. Key words Lignin olive seeds mechanochemistry mechanoradicals radical scavenging activity 1. Introduction Olives are one of the most important terrestiral product which have been acknowledged as nobel and nutritious fruits all over the world and also as high potential agricultural crop for Mediterranean countries including Turkey. Over the last decade the number of olive trees has increased by almost 60 and planted acreage has expanded by almost 25 in Turkey 1 . In connection with this olive oil production and the .