Dyeing Properties of Natural Dyes Extracted from Shea Butter Tree Bark (Vitellaria paradoxa)

Abstract

The research was designed due to the recent renewed interest in the use of natural dyes for the dyeing of textiles as a result of the problem(s) associated with dyeing using synthetic dye. Synthetic dyes are toxic, non-biodegradable and not friendly to the environment i.e. non-eco-friendly. Natural dye therefore is a perfect replacement for synthetic dyes due to their non-toxicity, biodegradable, non-hazardous and more eco-friendly. Natural dye used for the study was extracted from Vitellaria paradoxa Shea butter tree bark using the Soxhlet extraction technique. The extracted dye was applied on cotton fabric and evaluated based on dyeing parameters such as dye concentration, electrolyte concentration, time and temperature. Mordanting was carried out with potassium dichromate using the post-mordanting method. The percentage exhaustion–quantity of dye absorbed by cotton fibres and the fastness properties of the dyed fabric were evaluated. From the result obtained, it was observed that the percentage exhaustion increases with increase dye concentration with the highest percentage exhaustion of 95% which was obtained at 8ml dye concentration. However, increase in electrolyte concentration resulted in increase in the percentage exhaustion with the highest percentage exhaustion of 98% which was obtained at 6ml electrolyte concentration. This observation was in agreement with the effect of electrolyte concentration on percentage exhaustion. It was also observed that the percentage exhaustion increases with increase in time of dyeing. The highest percentage exhaustion of 96% which was obtained at 3h dyeing time and for temperature it was observed that that the rate of dyeing increases gradually by raising the temperature. The highest dye exhaustion of 95% was obtained at the temperature of 50oC. It may be suggested that the extracted dye in the aqueous medium is in aggregated form since they need an increase temperature to migrate into the fibre. However, the application of mordant on the dyed samples improved the dye-fibre bonding and enhanced the fastness properties with colour change rating of 3 and 4 with shade of light brown. Comparing with the mordanted samples, the mordanted samples have a better fastness properties with colour change of 5 with shade of cork. However, on the whole, it can be recommended that dye extracted from Vitellaria paradoxa Shea butter tree bark can be used to dye cotton fabric.