MACERATION-BASED EXTRACTION AND SPECTROSCOPIC CHARACTERISATION OF Sorghum bicolor LEAVES EXTRACT AS A NATURAL DYE ON COTTON FABRIC

Abstract

This study investigates the extraction, characterisation, and application of natural dyes derived from Sorghum bicolor leaves as an eco-friendly alternative to synthetic dyes in textile colouration. The dye was extracted using ethanol-based maceration and purified via gravity column chromatography, with thin-layer chromatography (TLC) employed for component monitoring. Phytochemical screening confirmed the presence of flavonoids, tannins, and alkaloids bioactive compounds known for their colourant and antioxidant properties. UV-Vis and FTIR spectroscopy further validated the presence of chromophoric and phenolic functional groups, suggesting the suitability of the extract for dyeing applications. The dye was applied to cotton fabrics, and colour fastness was evaluated with and without ferrous sulfate mordanting. At a 4% dye concentration, both mordanted and unmordanted fabrics recorded a Blue Wool Scale (BWS) rating of 5. However, at 8%, mordanted fabrics achieved a higher rating of 6, indicating improved light fastness. This enhancement is attributed to the formation of stable dye-metal complexes, which increase UV resistance and dye-fibre binding. Mordanted fabrics also exhibited better wash fastness due to the formation of insoluble dye–metal–fibre complexes that reduce dye leaching. Rubbing fastness was moderate for both treatments, with more colour transfer observed under wet conditions. Overall, Sorghum bicolor leaves extract shows strong potential as a sustainable natural dye source, offering acceptable fastness properties and aligning with environmentally responsible textile practices.