Tingimento de seda com corante natural erva-mate (Ilex paraguariensis)

• Ano de defesa: 2014
• Autor(a) principal: Giacomini, Fernando
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Departamento de Engenharia Química; Programa de Pós-Graduação em Engenharia Química; UEM; Maringá, PR; Centro de Tecnologia
• Palavras-chave em Português: Corantes naturais; Tingimento; Erva-mate (Ilex paraguariensis); Seda; Adsorção; Brasil.; Natural dye; Ilex paraguariensis; Silk; Dyeing; Brazil.; Engenharias; Engenharia Química
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/3831

Yerba mate (Ilex paraguariensis) is a native plant of the subtropical region of South America, where its leaves are consumed for the preparation of teas and hot and cold drinks. Its use as a dye is due to the presence of flavonoids, such as rutin and quercetina, as well as a large concentration of tannins. The objective of this work was to study the process of dyeing silk fabric with natural dye extracted from the leaves and stalks of roasted yerba mate. Optimal conditions, the kinetic, isotherms and thermodynamic parameters of dyeing were obtained. Natural dyes generally have low affinity with the fibers and are usually applied with mordants that act as fixation agents, including toxic metal salts of chromium, tin and copper. Mordants as potassium alum and tannin have environmentally safe application, being employed in pre-mordanting in this work. Concentration of yerba mate of 20 g L-1, pH 3 and 90 °C produced the best results of the adsorption of dye and color strength of the fabric. The potassium alum caused an increase in the adsorption of the dye. Nevertheless, its use did not influence the wash fastness. A yellowish brown color was obtained in dyed fabric, showing no change whatever mordant used. The model of pseudo-second order best represented the kinetic data of dyeing, indicating that the dye can be controlled by the chemisorption process. The model of Langmuir- Freundlich can be used to represent the equilibrium data, indicating a significant contribution of the process of chemisorption in a monolayer. Negative values of the Gibbs free energy (ΔG°) showed that the dyeing process is spontaneous and positive values of enthalpy (ΔH°) and entropy (ΔS°) indicate an endothermic process with and a high entropy change. Hence, the dye obtained from yerba mate can be an alternative source to synthetic dye for dyeing of silk.