Obtenção de hidrogel a partir do polímero natural quitosana para uso na remoção de metais em águas
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2021-06
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Catto, André Luis
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A água é considerada como um bem de importância mundial, com isso tratamentos avançados se tornam essenciais para remoção de metais e outros contaminantes que no tratamento convencional não conseguem ser removidos. Alguns adsorventes são considerados promissores para estes avanços, como é o caso do polissacarídeo quitosana, um polímero natural que está presente no exoesqueleto de crustáceos e pode ser obtido através dos restos destes animais. Devido suas características eficientes de adsorção de metais, o hidrogel obtido através da quitosana surge como uma alternativa para uso em diferentes aplicações. Neste sentido, o objetivo deste trabalho foi extrair a quitosana a partir da quitina presente no camarão e com isso desenvolver um hidrogel biodegradável e atóxico para aplicação em um processo de filtração que visa à remoção de metais em águas. Para se obter a quitosana a partir dos rejeitos de camarão foi utilizado o método de desacetilação, sendo após então produzido o hidrogel. A obtenção da quitina através dos resíduos de camarão foi realizada por meio de diferentes tratamentos químicos, até obtenção do material purificado. Já a reação de desacetilação da quitina foi realizada a partir de uma hidrólise básica, com a adição de uma solução de hidróxido de sódio (NaOH) na concentração de 42,3 % (m/v), sendo a reação conduzida em um reator batelada fechado com sistema de agitação a 165 rpm e mantido à temperatura de 100 °C por cerca de 2 h. Após o término da reação realizou-se as etapas de lavagem com água para a neutralização do pH e purificação da quitosana. Para a obtenção do hidrogel foi utilizada uma mistura de ácido acético e água junto à quitosana, usando processos mecânicos para a promover a precipitação do hidrogel. Para análise do hidrogel obtido foram avaliadas características físico-químicas e estruturais, por meio de análises físicas, químicas e morfológicas. Como resultados, obteve-se a quitosana com um grau de desacetilação de 81 % e um rendimento de cerca de 2 %, sendo estes valores semelhantes a outros estudos da literatura. Porém, a aplicação do hidrogel de quitosana à 2 % (Hidroquit) ao sistema de filtração de água contaminada com os metais cádmio (Cd), cobre (Cu) e chumbo (Pb) se mostrou ineficiente para a remoção destes metais, mesmo quando em pequenas quantidades, na concentração de 0,010 mg/L de Cd e 0,020 mg/L de Pb e Cu. Contudo, foi possível avaliar a efetividade do processo de obtenção da quitosana através de resíduos da espécie de camarão mais consumido na região sul do Brasil, sendo assim uma possibilidade para desenvolvimento de novas metodologias e estudos na área utilizando este material.
Water is considered a globally important, with that advanced treatments become essential for the removal of metals and other contaminants that in conventional treatment cannot be removed. Some adsorbents are considered promising for these advances, such as the polysaccharide chitosan, a natural polymer that is present in the crustaceans and can be obtained from the remains of these animals. Its efficient metal adsorption characteristics, the hydrogel obtained through chitosan appears as an alternative for use in different applications. The objective of this research was to extract chitosan from chitin present in shrimp and thus develop a biodegradable and non-toxic hydrogel for application in a filtration process aimed at removing metals from water. To obtain chitosan from shrimp tailings, the deacetylation method was used, after which the hydrogel was produced, the obtainment of chitin through shrimp residues was carried out through different chemical treatments, until obtaining the purified material. The chitin deacetylation reaction was carried out from a basic hydrolysis, with the addition of a solution of sodium hydroxide at a concentration of 42.3 % (m/v), and the reaction was conducted in a batch reactor closed with a stirring system at 165 rpm and kept at a temperature of 100 °C for about 2 h. The steps of washing with water were carried out to neutralize the pH and purify the chitosan. To obtain the hydrogel, a mixture of acetic acid and water together with chitosan was used, using mechanical processes to promote the precipitation of the hydrogel. For analysis of the obtained hydrogel, physicochemical and structural characteristics were evaluated through physical, chemical and morphological analyses. As a result, chitosan was obtained with a degree of deacetylation of 81% and a yield of about 2%, these values being similar to other studies in the literature. However, the application of 2% chitosan hydrogel (Hidroquit) to the filtration system of water contaminated with the metals cadmium (Cd), copper (Cu) and lead (Pb) proved to be inefficient for the removal of these metals, even when in small amounts, at a concentration of 0.010 mg/L of Cd and 0.020 mg/L of Pb and Cu. It was possible to evaluate the effectiveness of the process of obtaining chitosan through residues of the most consumed shrimp species in southern Brazil, thus being a possibility for the development of new methodologies and studies in the area using this material.
Water is considered a globally important, with that advanced treatments become essential for the removal of metals and other contaminants that in conventional treatment cannot be removed. Some adsorbents are considered promising for these advances, such as the polysaccharide chitosan, a natural polymer that is present in the crustaceans and can be obtained from the remains of these animals. Its efficient metal adsorption characteristics, the hydrogel obtained through chitosan appears as an alternative for use in different applications. The objective of this research was to extract chitosan from chitin present in shrimp and thus develop a biodegradable and non-toxic hydrogel for application in a filtration process aimed at removing metals from water. To obtain chitosan from shrimp tailings, the deacetylation method was used, after which the hydrogel was produced, the obtainment of chitin through shrimp residues was carried out through different chemical treatments, until obtaining the purified material. The chitin deacetylation reaction was carried out from a basic hydrolysis, with the addition of a solution of sodium hydroxide at a concentration of 42.3 % (m/v), and the reaction was conducted in a batch reactor closed with a stirring system at 165 rpm and kept at a temperature of 100 °C for about 2 h. The steps of washing with water were carried out to neutralize the pH and purify the chitosan. To obtain the hydrogel, a mixture of acetic acid and water together with chitosan was used, using mechanical processes to promote the precipitation of the hydrogel. For analysis of the obtained hydrogel, physicochemical and structural characteristics were evaluated through physical, chemical and morphological analyses. As a result, chitosan was obtained with a degree of deacetylation of 81% and a yield of about 2%, these values being similar to other studies in the literature. However, the application of 2% chitosan hydrogel (Hidroquit) to the filtration system of water contaminated with the metals cadmium (Cd), copper (Cu) and lead (Pb) proved to be inefficient for the removal of these metals, even when in small amounts, at a concentration of 0.010 mg/L of Cd and 0.020 mg/L of Pb and Cu. It was possible to evaluate the effectiveness of the process of obtaining chitosan through residues of the most consumed shrimp species in southern Brazil, thus being a possibility for the development of new methodologies and studies in the area using this material.
Descrição
Palavras-chave
Quitosana; Hidrogel; Remoção de metais; Águas; Chitosan; Hydrogel; Remove metals; Water
Citação
ROSA, Luma Thais Da. Obtenção de hidrogel a partir do polímero natural quitosana para uso na remoção de metais em águas. 2021. Monografia (Graduação em Engenharia Química) – Universidade do Vale do Taquari - Univates, Lajeado, 08 jul. 2021. Disponível em: http://hdl.handle.net/10737/3226.