Desenvolvimento e otimização de um polímero molecularmente impresso (MIP) para separação de xilose de resíduos sólidos da agricultura através de extração em fase sólida dispersiva (DSPE)
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Data
2023-01-27
Autores
Borges, Luis Fernando Tavares
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Universidade Estadual Paulista (Unesp)
Resumo
A agroindústria desempenha um papel de grande importância econômica, porém esse setor produz toneladas de resíduos que precisam de tratamento para evitar problemas ambientais. Nesse sentido, é importante desenvolver métodos de reaproveitamento desses resíduos, a fim de minimizar a contaminação do meio ambiente e fabricar produtos de maior valor agregado. Particularmente, industrias que geram resíduos lignocelulósicos apresentam potencial para separação de xilose, um açúcar com inúmeras aplicações no campo farmacêutico, alimentar e química fina. Diante disso, o presente estudo traz uma abordagem inédita sobre a síntese por precipitação de um polímero molecularmente impresso (MIP) com xilose, o qual pode ser empregado na extração em fase sólida dispersiva (MIP-DSPE) de resíduos lignocelulósicos agroindustriais. A primeira etapa do trabalho consistiu em determinar as condições de síntese do polímero, avaliando a porcentagem de adsorção do analito e Fator de Impressão (FI) do polímero. O MIP com maior FI (3,34) foi empregado em estudos de adsorção, onde demonstrou rápida cinética de religação a xilose, isotermas de adsorção que se adequam ao modelo de Langmuir e que pode ser reutilizado pelo menos três vezes. Estudos de seletividade mostraram que o MIP desenvolvido é seletivo, mostrando maior capacidade de adsorção de xilose frente a outros açúcares com estruturas semelhantes. Os polímeros foram caracterizados por potencial zeta, espectroscopia no infravermelho, microscopia eletrônica de varredura, microscopia de força atômica, método BET e análise termogravimétrica. A análise de BET indicou o sucesso da impressão molecular, apresentando área superficial de 8.7 m2/g e 69.4 m2/g para NIP e MIP, respectivamente e, volume de poros de 0,03 cm3/g e 0,26 cm3/g para NIP e MIP, respectivamente. Para separação de xilose em amostras reais, foi preparado o hidrolisado hemicelulósico de bagaço de laranja (BL) e de palha com bagaço da cana-de-açúcar (PBC), de acordo com o procedimento padrão “National Renewable Energy Laboratory – NREL”. Os polímeros MIP e NIP foram aplicados em DSPE com os hidrolisados BL e PBC, demonstrando maior porcentagem de adsorção de xilose em PBC (%adsMIP = 87,26 ± 0,98 e %adsNIP 66,12 ± 2,21). Por fim, para recuperação da xilose adsorvida aos polímeros, foi feito um procedimento simples de dessorção em água pura, alcançando 78,00 ± 7,65% e 85,23 ± 3,37% da xilose adsorvida no MIP e NIP, respectivamente.
Agribusiness plays a role of great economic importance, but this sector produces tons of waste that need treatment to avoid environmental problems. In this sense, it is important to develop methods for reusing these residues to minimize environmental contamination and manufacture products with greater added value. Particularly, industries that generate lignocellulosic residues have the potential for the separation of xylose, a sugar with numerous applications in the pharmaceutical, food, and fine chemical fields. In view of this, the present study brings an unprecedented approach to the synthesis by precipitation of a molecularly imprinted polymer (MIP) with xylose, which can be used in dispersive solid phase extraction (MIP-DSPE) of agroindustrial lignocellulosic residues. The first stage of the work consisted of determining the best conditions for polymer synthesis, evaluating the percentage of analyte adsorption, and the polymer’s Impression Factor (FI). The MIP with the highest FI (3.34) was used in adsorption studies, where it demonstrated fast rebinding kinetics to xylose, adsorption isotherms that fit the Langmuir model and that can be reused at least three times. Selectivity studies showed that the MIP developed is selective, showing a greater adsorption capacity for xylose compared to other sugars with similar structures. The polymers were characterized by Zeta Potential, Infrared Spectroscopy, Scanning Electron Microscopy, Atomic Force Microscopy, BET method, and thermogravimetric analysis. BET analysis indicated the success of molecular printing, showing a surface area of 8.7 m2/g and 69.4 m2/g for NIP and MIP, respectively, and pore volume of 0.03 cm3/g and 0.26 cm3/g for NIP and MIP, respectively. For the separation of xylose in real samples, the hemicellulosic hydrolyzate of orange bagasse (BL) and sugarcane straw and bagasse (PBC) was prepared, according to the standard procedure “National Renewable Energy Laboratory – NREL”. MIP and NIP polymers were applied in DSPE with BL and PBC hydrolysates, demonstrating a higher percentage of xylose adsorption on PBC (%adsMIP = 87.26 ± 0.98 and %adsNIP 66.12 ± 2.21). Finally, to recover the xylose adsorbed to the polymers, a simple procedure of desorption in pure water was performed, reaching 78.00 ± 7.65% and 85.23 ± 3.37% of xylose from MIP and NIP, respectively.
Agribusiness plays a role of great economic importance, but this sector produces tons of waste that need treatment to avoid environmental problems. In this sense, it is important to develop methods for reusing these residues to minimize environmental contamination and manufacture products with greater added value. Particularly, industries that generate lignocellulosic residues have the potential for the separation of xylose, a sugar with numerous applications in the pharmaceutical, food, and fine chemical fields. In view of this, the present study brings an unprecedented approach to the synthesis by precipitation of a molecularly imprinted polymer (MIP) with xylose, which can be used in dispersive solid phase extraction (MIP-DSPE) of agroindustrial lignocellulosic residues. The first stage of the work consisted of determining the best conditions for polymer synthesis, evaluating the percentage of analyte adsorption, and the polymer’s Impression Factor (FI). The MIP with the highest FI (3.34) was used in adsorption studies, where it demonstrated fast rebinding kinetics to xylose, adsorption isotherms that fit the Langmuir model and that can be reused at least three times. Selectivity studies showed that the MIP developed is selective, showing a greater adsorption capacity for xylose compared to other sugars with similar structures. The polymers were characterized by Zeta Potential, Infrared Spectroscopy, Scanning Electron Microscopy, Atomic Force Microscopy, BET method, and thermogravimetric analysis. BET analysis indicated the success of molecular printing, showing a surface area of 8.7 m2/g and 69.4 m2/g for NIP and MIP, respectively, and pore volume of 0.03 cm3/g and 0.26 cm3/g for NIP and MIP, respectively. For the separation of xylose in real samples, the hemicellulosic hydrolyzate of orange bagasse (BL) and sugarcane straw and bagasse (PBC) was prepared, according to the standard procedure “National Renewable Energy Laboratory – NREL”. MIP and NIP polymers were applied in DSPE with BL and PBC hydrolysates, demonstrating a higher percentage of xylose adsorption on PBC (%adsMIP = 87.26 ± 0.98 and %adsNIP 66.12 ± 2.21). Finally, to recover the xylose adsorbed to the polymers, a simple procedure of desorption in pure water was performed, reaching 78.00 ± 7.65% and 85.23 ± 3.37% of xylose from MIP and NIP, respectively.
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Palavras-chave
Açúcares, Polímeros, Materiais biomiméticos, Resíduos sólidos, Purificação