Estudo do tingimento de lã com corante natural de camomila (matricaria recutita l.)

• Autor(a) principal: Menegazzo, Maira Amanda Benedet
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/3760
• topic: Lã; Tingimento; Camomila; Corante; Adorção; Corante natural; Brasil.; Dyeing; Wool; Chamomile; Adsorption; Natural dye; Brazil.; Engenharias; Engenharia Química

Wool is a textile fiber of animal origin, characterized by various side groups, such as COOH and NH2, which are related for the dyeing process. Although commonly used in the dyeing of wool, synthetic dyes generate wastewater very pollutant, which is of great concern environmental. Fortunately, over the last decade, the use of natural dyes has gained importance. However, the use of dye have drawbacks such as difficulty in color reproduction, and empiricism understanding of the dyeing mechanism. Based on this background, the present study aimed to evaluate the dyeing process of wool fabrics with natural dye extracted from the flowers of chamomile (Matricaria recutita L). For this, the best dyeing conditions were studied, as well as the kinetic, the thermodynamic models and parameters. As the vast majority of natural dyes have low substantivity for textile fibers, it is necessary the use of mordant in dyeing with these dyes with the function of increasing the chemical attraction between dye and fiber. In this way, the tannin and aluminum potassium sulfate mordants was used in dyeing wool fiber with the dye chamomile. To identify the pH at which the surface of the wool fiber remains neutral and so adopt the pH of study the best dyeing condition, it was determined of point of zero charge of the surface of the fibers, which was pHPCZ 6,23. The best dyeing conditions were evaluated by 2³ factorial design. The initial concentration of 1000 mgL-1, pH 3 and 90 °C were the conditions that produced the best values of adsorption and color intensity (K/S). Fabrics dyed with chamomile dye showed good substantivity and good grades color fastness to washing. However, mordants tannin and potassium alum, did not provide significant improvements of the adsorption, color intensity (K/S) and color fastness to woshing. With the best parameters of dyeing, kinetics and equilibrium of the dyeing process were investigated. Kinetic experimental data was fitted by the pseudo-second-order model, indicating that the overall adsorption rate is controlled by chemisorption. Isotherms were the best fitted by the Langmuir-Freundlich model, which indicated a predominance of the chemisorption as well. Some contribution from physisorption was also noted. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were obtained. It was concluded that the mechanism of dyeing is endothermic and spontaneous. The entropy was positive, suggesting an increase in randomness in the solid-solution interface, caused by some structural changes in both dye and wool fiber. Tensile strength tests were conducted to verficiar if proecessos dyeings adopted influenced in the resistance of wool fabrics. The tests showed a slight loss of strength of dyed fabrics at 90 °C, pH 3 and concentration 1000 mgL-1, which may have occurred due to the weakening of the physical structure of the fibers. The characterization of the dyed fabrics and mordentados was performed by FTIR-ATR. It was concluded with this characterization that the potassium alum mordant seems not to participate in the dyeing, and that the complex fiber-tannin-dye was formed.