Avaliação de esferas de quitosana como adsorvente do corante Acid Blue 25
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Data
2019-02-19
Autores
Mendes, Carolina Rosai [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O aumento da relação produção e consumo exigem uma maior exploração dos recursos naturais e com isso a indústria têxtil gera grandes quantidades de efluentes contendo resíduos de corantes que são descartados no ambiente. Por conseqüência gera poluição visual no corpo do rio, além de desequilíbrio na microbiota e macrobiota. A Saccharomyces cerevisiae é considerado um biocatalizador de baixo custo e não patogênico. A parede da S. cerevisiae é descrita como capaz de adsorver as moléculas de corante. Outro material com possíveis sítios de interação com o corante é a quitosana um biopolímero derivado da desacetilação da quitina de crustáceos um resíduo pesqueiro. Uma das vantagens do uso da quitosana é a possibilidade de introduzir grupos amino quaternário na cadeia do polímero que garantem aumentar a capacidade adsortiva. Esse trabalho propõe o uso da quitosana para sintetizar esferas de quitosana, quitosana com levedura e quitosana quaternária para o uso nos tratamentos adsortivos do corante têxtil Acid Blue 25. Foram feitos estudos cinéticos, isotermas, termodinâmica, comportamento reológico da matéria, FT-IR, MEV e toxicidade. Os resultados mostraram que os adsorventes respeitaram o modelo de pseudo-segunda ordem, porém pode-se constatar também a ocorrência de difusão intrapartícula nos materiais. A aplicação da esfera de quitosana quaternária produziu melhores resultados nos estudos adsortivos e se ajustou ao modelo de Freundlich em todos os pH. Os outros adsorventes de ajustaram no modelo de Langmuir em pH acido e Freundlich em pH alcalino. Os estudos termodinâmicos confirmaram que a adsorção é uma reação endotérmica e espontânea. As analises em FT-IR confirmaram que para os materiais de esfera de quitosana e quitosna com levedura está ocorrendo quimiossorção em pH ácido devido a protonação do meio, já no pH alcalino estava ocorrendo uma físiossorção. O material de quitosana quaternária ocorre quimiossorção para ambos os pH. Os materiais apresentaram alterações no volume após a adsorção. Esse resultado se deve a hidrofilicidade dos materiais, principalmente as esferas de quitosana quaternária que apresentou um inchamento de S= 5,300%. O MEV indicou que a quitosana quaternária possui uma superfície de contato muito maior do que os outros materiais devido à porosidade. Os materiais de quitosana com levedura e quitosana quaternária apresentaram redução da toxicidade após a adsorção. A esfera de quitosana quaternária mostrou capacidade adsortiva superior, sendo um possível material para o uso nos tratamentos adsortivos na indústria têxtil.
The increased production and consumption ratio require a greater exploitation of the natural resources and thus the textile industry generates large amounts of effluents containing residues of dyes that are discarded in the environment. Consequently it generates visual pollution in the body of the river, besides imbalance in the microbiota and macrobiota. Saccharomyces cerevisiae is considered a low-cost, non-pathogenic biocatalyst. The S. cerevisiae wall is described as capable of adsorbing the dye molecules. Another material with possible sites of interaction with the dye is chitosan a biopolymer derived from the deacetylation of chitin from crustaceans a fishery residue. One of the advantages of the use of chitosan is the possibility of introducing groups of quaternary ammonium in the polymer chain that confirms to increase the adsorptive capacity. This study proposes the use of chitosan to synthesize beads of chitosan, chitosan with yeast and quaternary chitosan for use in adsorptive treatments of Acid Blue 25 dye. Kinetic studies, isotherms, thermodynamics, rheological behavior of matter, FT-IR, MEV and toxicity were performed. The results showed that the adsorbents indicated the pseudo-second order model, but also the occurrence of intraparticle diffusion in the materials. The quaternary chitosan beads obtained the best results in the adsorption studies and adjusted to the Freundlich model at all pH. The other adsorbents were adjusted in the Langmuir model in acid pH and Freundlich in alkaline pH. Thermodynamic studies have confirmed that adsorption is an endothermic and spontaneous reaction. FT-IR analyzes confirmed that for chitosan and yeast chitosan beads materials chemisorption is occurring at acid pH due to protonation of the medium, already at the alkaline pH a physisorption was occurring. The quaternary chitosan material is occurring chemisorption for both pH. The materials presented changes in the volume after the adsorption. This result is due to the hydrophilicity of the materials, especially the quaternary chitosan beads which presented a 5,300% swelling. SEM indicated that quaternary chitosan has a much larger contact surface than other materials due to porosity. The chitosan materials with yeast and quaternary chitosan showed reduction in toxicity after adsorption. The quaternary chitosan beads showed superior adsorptive capacity, being a possible material for use in adsorptive treatments in the textile industry.
The increased production and consumption ratio require a greater exploitation of the natural resources and thus the textile industry generates large amounts of effluents containing residues of dyes that are discarded in the environment. Consequently it generates visual pollution in the body of the river, besides imbalance in the microbiota and macrobiota. Saccharomyces cerevisiae is considered a low-cost, non-pathogenic biocatalyst. The S. cerevisiae wall is described as capable of adsorbing the dye molecules. Another material with possible sites of interaction with the dye is chitosan a biopolymer derived from the deacetylation of chitin from crustaceans a fishery residue. One of the advantages of the use of chitosan is the possibility of introducing groups of quaternary ammonium in the polymer chain that confirms to increase the adsorptive capacity. This study proposes the use of chitosan to synthesize beads of chitosan, chitosan with yeast and quaternary chitosan for use in adsorptive treatments of Acid Blue 25 dye. Kinetic studies, isotherms, thermodynamics, rheological behavior of matter, FT-IR, MEV and toxicity were performed. The results showed that the adsorbents indicated the pseudo-second order model, but also the occurrence of intraparticle diffusion in the materials. The quaternary chitosan beads obtained the best results in the adsorption studies and adjusted to the Freundlich model at all pH. The other adsorbents were adjusted in the Langmuir model in acid pH and Freundlich in alkaline pH. Thermodynamic studies have confirmed that adsorption is an endothermic and spontaneous reaction. FT-IR analyzes confirmed that for chitosan and yeast chitosan beads materials chemisorption is occurring at acid pH due to protonation of the medium, already at the alkaline pH a physisorption was occurring. The quaternary chitosan material is occurring chemisorption for both pH. The materials presented changes in the volume after the adsorption. This result is due to the hydrophilicity of the materials, especially the quaternary chitosan beads which presented a 5,300% swelling. SEM indicated that quaternary chitosan has a much larger contact surface than other materials due to porosity. The chitosan materials with yeast and quaternary chitosan showed reduction in toxicity after adsorption. The quaternary chitosan beads showed superior adsorptive capacity, being a possible material for use in adsorptive treatments in the textile industry.
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Palavras-chave
Toxicidade, Cinética, Biopolímero, Isotermas, Saccharomyces cerevisiae, Toxicity, Kinetics, Biopolymer, Isotherms