Avaliação da adsorção de cromo em quitosana submetida a tratamento com líquidos iônicos
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Dissertação
Data
2018
Autores
Eliodório, K. P.
Orientador
Giannetti, Andréia de Araújo Morandim
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Citação
ELIODÓRIO, K. P. Avaliação da adsorção de cromo em quitosana submetida a tratamento com líquidos iônicos. 2018. 175 f. Dissertação (Mestrado em Engenharia Química) - Centro Universitário FEI, São Bernardo do Campo, 2018 Disponível em: . Acesso em: 26 jul. 2018.
Texto completo (DOI)
Palavras-chave
Cromo,Quitosana,Líquidos iônicos
Resumo
O presente trabalho teve como objetivo estudar a modificação de quitosana com líquidos iônicos de baixo custo e seu emprego na adsorção de cromo hexavalente presente em efluentes. Além disso, foi verificada a influência da
temperatura, do tempo de contato, do pH da solução, bem como a relação entre a concentração de cromo e a quantidade de adsorvente nos processos de adsorção deste metal pesado. Dessa forma, foram sintetizados e caracterizados via RMN os LIs acetato de n-butilamônio, acetato de sec-butilamônio e acetato de tercbutilamônio.
Posteriormente, os mesmos foram empregados no tratamento da quitosana (Q), gerando três novos adsorventes (QN, QS e QT), que foram caracterizados por MEV, FTIR, BET, DR, DTP e DRX. As análises possibilitaram a verificação das alterações ocorridas na quitosana após o tratamento com os LIs, a qual pôde, então, ser aplicada na adsorção de cromo hexavalente. Nessa etapa, comparou-se a eficiência das quitosanas pura e tratada em processos de adsorção
do íon metálico, sendo observado o aumento na capacidade de adsorção do material após o tratamento. As quitosanas tratadas foram submetidas a ensaios para a determinação das melhores condições para a adsorção, sendo verificada uma dosagem ideal de 2 g.L-1, pH 3, temperatura de 20°C e tempo de contato de 120 minutos. Durante o ensaio de temperatura, ajustou-se os dados aos modelos de Freundlich e Langmuir, sendo verificadas capacidades de adsorção máximas de 142,05; 131,58 e 146,63 mg.g-1 para QN, QS e QT, respectivamente. Ao investigar se a termodinâmica, foi possível notar entalpias de adsorção negativas, caracterizando um processo exotérmico, favorecido pela redução de temperatura. O ajuste cinético foi realizado pelo modelo de Weber-Morris, sendo verificadas capacidade de adsorção de 89,50; 99,43 e 100,70 mg.g-1 para QN, QS e QT. Comparado a outros adsorventes reportados, os três adsorventes apresentaram bom desempenho com um preparo relativamente simples, indicando possibilidade de aplicação industrial.
This study aimed at verifying the modification of chitosan with low-cost ionic liquids, and its use in the adsorption of hexavalent chromium present in the effluents. Additionally, we sought to analyze the influence of temperature, contact time, the solution s pH, as well as the relationship between the concentration of chromium and the amount of adsorbent in this heavy metal. Therefore, we synthesized nbutylammonium acetate, sec-butylammonium acetate, and tert-butylammonium acetate. Subsequently, these ILs were characterized through NMR. Afterwards, those chemicals were used in the processing of chitosan (Q), which generated three new adsorbents (QN, QS, and QT) that were characterized through SEM, FTIR, BET, RD, PSD, and XRD. The analyses enabled us to verify the activation of chitosan after the treatment with the ILs, which could then be used in the adsorption process of hexavalent chromium. In this step, we compared the efficiency of the pure and activated chitosans in metallic ion adsorption processes, with the increase in the adsorption capacity of the material after its treatment. Activated chitosans were submitted to adsorbent dosage tests to determine the best conditions for the adsorption, with an optimal dosage of 2 g.L-1, pH 3, temperature of 20ºC, and contact time of 120 min. During the temperature test, data was adjusted to the Freundlich and Langmuir models, which enabled us to verify the maximum adsorption capacities of 142.05; 131.58 and 146.63 mg.g-1 for QN, QS, and QT, respectively.Through the analysis of the thermodynamic parameters, negative enthalpy of adsorption was noticed, characterizing an exothermic process, which is favored by the reduction of temperature. The kinetic adjustment was carried out through the Weber-Morris model, enabling us to verify an adsorption capacity of 89.50, 99.43, and 100.70 mg.g- 1 for QN, QS, and QT. Compared to other adsorbents reported, the three adsorbents displayed good performance with relatively simple preparation, which pointed to the possibility of industrial application..
This study aimed at verifying the modification of chitosan with low-cost ionic liquids, and its use in the adsorption of hexavalent chromium present in the effluents. Additionally, we sought to analyze the influence of temperature, contact time, the solution s pH, as well as the relationship between the concentration of chromium and the amount of adsorbent in this heavy metal. Therefore, we synthesized nbutylammonium acetate, sec-butylammonium acetate, and tert-butylammonium acetate. Subsequently, these ILs were characterized through NMR. Afterwards, those chemicals were used in the processing of chitosan (Q), which generated three new adsorbents (QN, QS, and QT) that were characterized through SEM, FTIR, BET, RD, PSD, and XRD. The analyses enabled us to verify the activation of chitosan after the treatment with the ILs, which could then be used in the adsorption process of hexavalent chromium. In this step, we compared the efficiency of the pure and activated chitosans in metallic ion adsorption processes, with the increase in the adsorption capacity of the material after its treatment. Activated chitosans were submitted to adsorbent dosage tests to determine the best conditions for the adsorption, with an optimal dosage of 2 g.L-1, pH 3, temperature of 20ºC, and contact time of 120 min. During the temperature test, data was adjusted to the Freundlich and Langmuir models, which enabled us to verify the maximum adsorption capacities of 142.05; 131.58 and 146.63 mg.g-1 for QN, QS, and QT, respectively.Through the analysis of the thermodynamic parameters, negative enthalpy of adsorption was noticed, characterizing an exothermic process, which is favored by the reduction of temperature. The kinetic adjustment was carried out through the Weber-Morris model, enabling us to verify an adsorption capacity of 89.50, 99.43, and 100.70 mg.g- 1 for QN, QS, and QT. Compared to other adsorbents reported, the three adsorbents displayed good performance with relatively simple preparation, which pointed to the possibility of industrial application..