Influence of pH and fabric cationisation on functional properties of natural dyed cotton using extract from used tea bag

Abstract

Abstract The study focuses on the eco-friendly dyeing of cotton fabric by extracts from used tea bag without any metal mordant and also on investigating the effect of pH and fabric cationization on the properties of that dyed cotton. Coloured liquor was collected from leftover tea bags using water in boiling. Prior to dyeing, the cotton fabric was cationised with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) at different percentage, followed by dyeing with tea liquor at different concentrations and different pH. The colour fastness and colorimetric properties (CIELab, CIELch, ΔE and K/S) of dyed cotton fabrics were then investigated. UV-Vis spectroscopy was used to calcualte exhaustion and fixation percentages. FTIR analysis was also carried out. The best results were obtained for pH 13. At pH 13, the highest exhaustion percentage was 88.6% for cationised fabric with cationiser concentration 55 g/L whereas it was 0.75% for non-cationised fabric and 3.6% for mordanted (KAI(SO₄)₂.12H₂O) fabric. Also, the colour fastness to washing, rubbing and perspiration of cationised fabric were excellent (4–5) than those of non-cationised fabric; nevertheless, the former has lower light fastness. Their higher washing and rubbing fastness were attempted to explain within the framework of density functional theory (DFT) by their considerably strong interaction between theaflavins, one of the main colouring components of tea dye and cationised cellulose monomer. All findings from this study explicitly demonstrate the significance of pH and fabric cationisation on dyeing and the functional properties of dyed fabric.