Rumex abyssinicus (mekmeko) extract as cleaner approach for dyeing in product manufacture: Optimization and modeling studies

Abstract

AbstractSome of the synthetica dyes, used in leather dyeing, are carcinogenic. Hence an eco‐benign dyeing is made for leather based on mekmeko (Rumex abyssinicus) extract that contains the anthraquinones, a natural dyeing constituent containing bioactive compounds. It is the first time where this material is tried for dyeing application in leather manufacture. The Langmuir adsorption isotherm is supported by a thermodynamic model and is augmented using intra‐particle diffusion model. The optimum concentration of the extract for dyeing was 20% based on the weight of the undyed crust leather (dry). For the modeling and optimization studies of mekmeko‐based dyeing process, response surface methodologies and artificial neural network were used. The pH, temperature, and time effects on exhaustion of the dye were studied. The optimized conditions were found to be pH 4.5, temperature 60 °C, and duration 5.5 hr. The exhaustion level of mekmeko extract in dyeing process under optimized conditions was found to be 72%. Kinetic models explain adsorption using different adsorption isotherms. The leathers were treated with different pre‐ or post‐mordants dyeing with mekmeko, and multiple colors were obtained depending on the types of mordants used. The overall results in this study indicated that the mekmeko‐dyed leathers exhibit good fastness and organoleptic characteristics.