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Esta investigação teve como objetivo a avaliação de novos adsorventes para a valorização eficiente de resíduos da vinificação e da produção de azeite através da obtenção de produtos de valor acrescentado, especificamente polifenóis. Foram projetados e sintetizados diversos materiais molecularmente impressos (MIPs), considerando diferentes tipos de moléculas molde e variando a sua composição química e características morfológicas. Tendo em consideração estudos recentes nesta área, a 4-vinilpiridina (4VP) foi usada como monómero funcional na generalidade dos adsorventes sintetizados. Procurou-se potenciar a forte interação entre os grupos piridil e muitos polifenóis. Para efeitos comparativos, foram também realizados testes de adsorção/desorção de polifenóis com materiais sintéticos disponíveis comercialmente.
Produziram-se extratos de bagaço, antes e após a destilação, considerando diferentes solventes para remoção dos polifenóis, nomeadamente etanol/água 80/20, acetonitrilo/dimetilformamida (50/50) e acetato de etilo/etanol (50/50). Usou-se a água ruça de uma cooperativa de produção de azeite como possível fonte de polifenóis de produtos derivados da oliveira. Procedeu-se à análise por HPLC-DAD dos extratos para obtenção dos respetivos perfis em termos de compostos fenólicos.
Realizaram-se testes de retenção dos polifenóis contidos nos extratos de bagaço e na água ruça utilizando os diferentes adsorventes. Notavelmente, as medições realizadas demonstram uma superior capacidade dos materiais sintetizados com 4VP para reter os polifenóis presentes nos diversos extratos de bagaço e também na água ruça. Os resultados obtidos mostram que a elevada capacidade de retenção de polifenóis com adsorventes 4VP se verifica com extratos em solventes muito diferentes, incluindo solventes orgânicos e misturas aquosas, confirmando observações análogas com outras matrizes vegetais.
Analisou-se a dinâmica de adsorção de polifenóis contidos em extratos de bagaço e na água ruça com adsorventes MIP selecionados e considerando processos fechados ou contínuos. Testou-se a concentração e fracionamento dos polifenóis através de ciclos de adsorção/desorção. Com um extrato de bagaço foi demonstrada a simplificação do perfil fenólico original e produzida uma fração enriquecida em flavonoides. Com a água ruça foi produzida uma sequência de frações orgânicas mostrando o enriquecimento alcançado com secoiridóides e flavonoides, relativamente a álcoois e ácidos fenólicos. Os adsorventes 4VP mostraram-se também promissores para a melhoria da eficiência no tratamento de águas ruças e águas da curtição da azeitona.
The aim of this research was the assessment of novel adsorbents for the efficient valorization of winemaking and olive oil production residues through the production of added-value compounds, specifically polyphenols. Different molecularly imprinted materials (MIPs) were designed and synthesized considering alternative template molecules and changing the chemical composition and morphological features of the adsorbents. Based on recent studies in this area, the 4-vinylpyridine (4VP) functional monomer was generally used in the synthesis of the adsorbents. The strong interactions between the pyridyl groups and many polyphenols were thus explored. For comparative purposes, the adsorption/desorption testing also included the use of commercially available synthetic materials. Grape pomace, before and after distillation, was used to produce extracts containing polyphenols in ethanol/water (80/20), acetonitrile/dimethylformamide 50/50 and ethyl acetate/ethanol (50/50). The olive mill wastewater provided by an olive oil producers association was used in this research as a source of polyphenols in products derived from olive tree. The phenolic profile of the different extracts was obtained through HPLC-DAD analysis. The retention of the polyphenols contained in the diverse grape pomace extracts and olive mill wastewater was assessed with the different adsorbents. Notably, the measurements performed shown the superior capacity of the materials synthesized with 4VP to retain the polyphenols in the grape pomace extracts and olive mill wastewater. These results evidence that the high capacity of the 4VP adsorbents to retain polyphenols is possible with extracts in very different solvents, including organic and also aqueous mixtures. These findings with grape pomace extracts and olive mill wastewater confirm recent outcomes with 4VP adsorbents involving other plant matrices. The dynamics of adsorption of polyphenols in grape pomace extracts and olive mill wastewater was measured with selected MIPs considering batch and continuous processes. The concentration and fractionation of polyphenols was assessed through sorption/desorption cycles. With a grape pomace extract was demonstrated the simplification of the initial phenolic profile and a fraction enriched with flavonoids was obtained. With the olive mill wastewater a sequence of organic fractions was produced showing the enrichment attained for secoiridoids and flavonoids, in comparison to phenolic alcohols and acids. It was also demonstrated that the 4VP adsorbents are promising materials for the efficiency improvement in the treatment of olive mill wastewater and olive debbitering wastewater.
The aim of this research was the assessment of novel adsorbents for the efficient valorization of winemaking and olive oil production residues through the production of added-value compounds, specifically polyphenols. Different molecularly imprinted materials (MIPs) were designed and synthesized considering alternative template molecules and changing the chemical composition and morphological features of the adsorbents. Based on recent studies in this area, the 4-vinylpyridine (4VP) functional monomer was generally used in the synthesis of the adsorbents. The strong interactions between the pyridyl groups and many polyphenols were thus explored. For comparative purposes, the adsorption/desorption testing also included the use of commercially available synthetic materials. Grape pomace, before and after distillation, was used to produce extracts containing polyphenols in ethanol/water (80/20), acetonitrile/dimethylformamide 50/50 and ethyl acetate/ethanol (50/50). The olive mill wastewater provided by an olive oil producers association was used in this research as a source of polyphenols in products derived from olive tree. The phenolic profile of the different extracts was obtained through HPLC-DAD analysis. The retention of the polyphenols contained in the diverse grape pomace extracts and olive mill wastewater was assessed with the different adsorbents. Notably, the measurements performed shown the superior capacity of the materials synthesized with 4VP to retain the polyphenols in the grape pomace extracts and olive mill wastewater. These results evidence that the high capacity of the 4VP adsorbents to retain polyphenols is possible with extracts in very different solvents, including organic and also aqueous mixtures. These findings with grape pomace extracts and olive mill wastewater confirm recent outcomes with 4VP adsorbents involving other plant matrices. The dynamics of adsorption of polyphenols in grape pomace extracts and olive mill wastewater was measured with selected MIPs considering batch and continuous processes. The concentration and fractionation of polyphenols was assessed through sorption/desorption cycles. With a grape pomace extract was demonstrated the simplification of the initial phenolic profile and a fraction enriched with flavonoids was obtained. With the olive mill wastewater a sequence of organic fractions was produced showing the enrichment attained for secoiridoids and flavonoids, in comparison to phenolic alcohols and acids. It was also demonstrated that the 4VP adsorbents are promising materials for the efficiency improvement in the treatment of olive mill wastewater and olive debbitering wastewater.
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Keywords
Impressão molecular Adsorventes Polifenóis Bioeconomia vircular Resíduos da vinificação Águas ruças