Avaliação do uso de folhas de amora (Morus nigra L.) como biossorvente para adsorção de cobre e zinco de amostras aquosas
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Data
2022-08-18
Autores
Silva, Toncler da
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Universidade Estadual Paulista (Unesp)
Resumo
A contaminação dos recursos hídricos, seja por substâncias orgânicas ou inorgânicas, é um problema ambiental evidente e discutido mundialmente. A manutenção ou melhoria dos recursos hídricos é essencial à necessidade abrangente da humanidade por alimentos e segurança energética. Tendo em vista a necessidade de remoção de espécies metálicas de amostras aquosas, procedimentos/técnicas vêm sendo adotadas, dentre elas a extração em fase sólida. Visando diversificar as opções de materiais disponíveis para a adsorção (principalmente, buscando diminuir o custo do procedimento), a utilização de biossorventes se tornou um atrativo. Sendo o principal objetivo do presente trabalho a utilização da folha de amora (Morus nigra L.) como material para tratamento de amostras contaminadas com metais, buscando aproveitar esta matéria-prima. Além disso, caracterizar o material a fim de identificar os grupos químicos utilizando a Espectroscopia no infravermelho por transformada de Fourier (FTIR), elucidar a estrutura do material, utilizando a Ressonância Magnética Nuclear (RMN) com polarização cruzada, caracterizar a composição química do adsorvente pelo método de análise elementar, determinar o pH no qual a superfície do adsorvente possui carga nula (pHpzc). Resultados referentes ao espectro de FTIR e RMN identificaram os grupos químicos funcionais responsáveis pela interação entre o biossorvente e analito, sendo a folha de amora um material rico em celulose. A análise elementar detectou 23 g kg-1 de nitrogênio e 0.9 g kg-1 de enxofre presentes no material. Juntamente, o teste de pHpzc ajuda a entender a melhor faixa de pH para os experimentos, sendo o ponto de carga zero da folha de amora o pH 8.7. O material foi aplicado em estudos de adsorção em função do tempo mínimo de contato, pH e da capacidade máxima de sorção dos íons Cu(II) e Zn(II), os estudos comprovaram que o tempo mínimo de contato foi de 30 minutos para o cobre e zinco, seguindo o modelo de pseudo-segunda ordem, o pH ideal para a adsorção de cobre se deu próximo de 6 e entre 4 e 6 para zinco, no estudo de capacidade máxima foi demonstrado que cada grama de biossorvente conseguiu adsorver 0.37 mmol de íons de Cu(II) e 0.50 mmol de íons Zn(II), seguindo a isoterma de Langmuir, demonstrando que a adsorção acontece em monocamada do material biossorvente.
Contamination of water resources, whether by organic or inorganic substances, is an evident and discussed environmental problem worldwide. Maintaining or improving water resources is essential to humanity's overarching need for food and energy security. Considering the need to remove metallic species from aqueous samples, procedures/techniques have been adopted, including solid phase extraction. In order to diversify the options of materials available for adsorption (mainly, seeking to reduce the cost of the procedure), the use of biosorbents has become an attraction. Being the main objective of the present work the use of the blackberry leaf (Morus nigra L.) as material for treatment of samples contaminated with metals, seeking to take advantage of this raw material. In addition, characterize the material in order to identify the chemical groups using Fourier Transform Infrared Spectroscopy (FTIR), elucidate the structure of the material, using Cross-polarized Nuclear Magnetic Resonance (NMR), characterize the chemical composition of the adsorbent by the elemental analysis method, determine the pH at which the adsorbent surface has zero charge (pHpzc). Results referring to the FTIR and NMR spectrum identified the functional chemical groups responsible for the interaction between the biosorbent and the analyte, with the blackberry leaf being a material rich in cellulose. Elemental analysis detected 23 g kg-1 of nitrogen and 0.9 g kg-1 of sulfur present in the material. Along with the pHpzc test which helps us to understand the best pH range for the experiments, the blackberry leaf zero charge point being pH 8.7. The material was applied in adsorption studies as a function of the minimum contact time, pH and the maximum sorption capacity of Cu(II) and Zn(II) ions, the studies proved that the minimum contact time was 30 minutes for the copper and zinc, following the pseudo-second order model, the ideal pH for copper adsorption was close to 6 and between 4 and 6 for zinc, in the maximum capacity study it was demonstrated that each gram of biosorbent was able to adsorb 0.37 mmol of Cu(II) ions and 0.50 mmol of Zn(II) ions, following the Langmuir isotherm, demonstrating that the adsorption occurs in a monolayer of the biosorbent material.
Contamination of water resources, whether by organic or inorganic substances, is an evident and discussed environmental problem worldwide. Maintaining or improving water resources is essential to humanity's overarching need for food and energy security. Considering the need to remove metallic species from aqueous samples, procedures/techniques have been adopted, including solid phase extraction. In order to diversify the options of materials available for adsorption (mainly, seeking to reduce the cost of the procedure), the use of biosorbents has become an attraction. Being the main objective of the present work the use of the blackberry leaf (Morus nigra L.) as material for treatment of samples contaminated with metals, seeking to take advantage of this raw material. In addition, characterize the material in order to identify the chemical groups using Fourier Transform Infrared Spectroscopy (FTIR), elucidate the structure of the material, using Cross-polarized Nuclear Magnetic Resonance (NMR), characterize the chemical composition of the adsorbent by the elemental analysis method, determine the pH at which the adsorbent surface has zero charge (pHpzc). Results referring to the FTIR and NMR spectrum identified the functional chemical groups responsible for the interaction between the biosorbent and the analyte, with the blackberry leaf being a material rich in cellulose. Elemental analysis detected 23 g kg-1 of nitrogen and 0.9 g kg-1 of sulfur present in the material. Along with the pHpzc test which helps us to understand the best pH range for the experiments, the blackberry leaf zero charge point being pH 8.7. The material was applied in adsorption studies as a function of the minimum contact time, pH and the maximum sorption capacity of Cu(II) and Zn(II) ions, the studies proved that the minimum contact time was 30 minutes for the copper and zinc, following the pseudo-second order model, the ideal pH for copper adsorption was close to 6 and between 4 and 6 for zinc, in the maximum capacity study it was demonstrated that each gram of biosorbent was able to adsorb 0.37 mmol of Cu(II) ions and 0.50 mmol of Zn(II) ions, following the Langmuir isotherm, demonstrating that the adsorption occurs in a monolayer of the biosorbent material.
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Adsorção, Metais, Biossorventes, Biotecnologia ambiental, Adsorption, Metals, Biosorbents, Environmental biotechnology