Extraction and application of natural dyes from Allium Burdickii on cotton substrate

Abstract

The quest for sustainable and cleaner production in the contemporary textile processing industry has attracted interest in natural dyeing of textiles because of their biodegradable nature and compatibility with the environment. Synthetic dyes have been in use for a long time due to their abundance, uniformity, reproducibility and applicability, but have limitations such as toxicity, non-biodegradability and environmental pollution. Lately, due to environmental considerations, commercial interest in natural dyes has gained prominence. Although natural dyes have been exploited from various plants such as Allium cepa skin, saffron and pomegranate rind, there is still a wide scope of unexploited resource such as Allium burdickii that grows in the tropical and temperate regions. These natural dyes are however non-substantive hence their application requires the assistance of mordants. This research therefore concerns with the extraction of a natural dye and investigation of the factors that influence the extraction and dyeing processes. The research was carried out from MIT Laboratory, Kyambogo University and Uganda National Research Institute. The objectives were to extract, characterize, assess the dyeing of 100% cotton fabric using natural dye extracted from Allium burdickii plant and analyze fastness properties of the dyed fabrics. Using both the leaves and bulbs of the Allium burdickii plant, dye samples were prepared using aqueous and solvent (methanol and ethanol) extraction methods and further investigated for the different physico-chemicals present. Using Box-Behnken experimental design four factors namely dyeing temperature, time, concentration of mordant and pH where chosen and dyeing conditions evaluated while applying the plant extract and mango bark (natural mordant) on cotton fabrics using pre, simultaneous and post mordanting methods and the fastness properties of the dyed fabrics evaluated using Mintab statistical approach. The study established presence of chromophores in the bulb but not in the leaves, aqueous extraction method as the best method and further optimized its extraction temperature, time and mass to liquor ratio as 60 0 C, 60 minutes and 1:20 respectively. Some of the physico- chemicals that were present in the bulb extract were flavonoids, carbohydrates and proteins whereas saponins were absent in the leaves of the plant. Amongst the three mordanting techniques, post mordanting emerged as the best. The research further established that samples with low percentage of mordant (10% on weight of fabric) exhibited better wash and perspiration fastness with a rating of 3-4 whereas light and rubbing fastness (wet and dry) for all the mordanting techniques showed acceptable fastness of 4/5-5. From the research, the dye can be classified as a plant polygenetic, basic and mordant dye producing red dye. Under optimized extraction conditions, low concentrations of mordant and mass to liquor ratio, the dye extracted from bulbs of the plant showed acceptable fastness properties hence can therefore be utilized on cotton substrate. Besides that, this research has provided insights for the utilization of locally sourced Allium burdickii plant for dye applications in textiles. Nevertheless, to maximise the full potential presented by the Allium burdickii plant, there is need for further research in the quantitative and qualitative analysis of physico-chemical in the dye and use of different mordants and substrates during dyeing process.