Extraction and application of dyestuffs from the leaves of guinea corn and onion skin

Abstract

This research work is aimed at assessing the dyeing and colouring  potentials of ethanol extracts from the leaves of guinea corn and the skin of onion. It is intended to apply the purified dye extracts on textile, drink
and food. The leaves of guinea corn (Sorghum bicolor) and the skin of onion (Allium cepa) were collected, chopped, dried and pulverized. The powdered samples were extracted using ethanol absolute as solvent. The
guinea corn leaves yielded dark red colour while the onion skin gave brownish red colour. The crude dyestuffs were purified by recrystallization in carbon tetrachloride (CCl4). The percentage yields, melting points, pH and
RF values are 10.64% and 9.83%, 186 °C and 194 °C, 7.10 and 5.96, 0.84 and 0.53 respectively. UV/visible absorptions and IR spectra of dye  samples were recorded. The dye samples obtained were used to colour food (pap) and drink (illicit gin). The dye baths made from these dyestuffs were used to dye some cotton fabrics, unmordanted and mordanted  scoured fabrics. The products got from these dyeings, showed varied colour
shades and hues. Wash and light fastness properties were carried out on the dyed fabrics. Both dyed fabrics experienced improved wash and light fastness with mordanting.

Keywords: Natural dyes, textile dyeing, wash and light fastness, food and drink colouring.