Extraction, identification and adsorption-kinetic studies of a natural color component from G. sepium

Abstract

The use of synthetic dyes causes environmental pollution as majority of these dyes are toxic and non-biodegradable. Natural dyes on the other hand have proved to be eco-friendly, biodegra- dable and highly compatible with the environ-ment. Consequently, dyes derived from natural sources have emerged as important alternatives to synthetic dyes. In the present work, the major color component isolated from the pods of G. sepium plant is morin, which is a flavonoid moiety. The dyeing behaviour of this component on silk yarn was investigated. Mordanting stu- dies have indicated that the post-mordanting method was found to be a better method com-pared to pre-mordanting. Variation of pH on dye extract pointed out that the maximum absorbance was at pH 4 and hence all the dyeing studies have been carried out at that pH. Thermodynamic parameters were determined by studying the dyeing process at different temperatures. Heat of dyeing was positive which indicated the dyeing process was endothermic. The adsorption process of morin on silk was tested with Langmuir, Freundlich and Tempkin- Pyzhev isotherm models. The adsorption process followed both the Langmuir and Freund- lich isotherms. The value of regression coefficient, however, indicated that the Langmuir isotherm was a better fit than the Freundlich isotherm. These results signified that the adsor- ption of morin on silk yarn was homogeneous in nature with the formation of a monolayer. Hence, the dye obtained from the pods of G. sepium plant may be an alternative source to synthetic dye for the dyeing of silk as well as other textile fabrics.