Green, eco-friendly and sustainable alternative in dyeing cotton fabric using aqueous extract Mucuna slonaei F dye: effects of metal salts pre-mordanting on color strength and fastness properties

Natural dye extracted from Mucuna slonaei F leaves (MSL) was used as green, sustainable and eco-friendly alternative in coloring cotton fabric with and without sodium chloride (NaCl), ferrous sulfate (FeSO4·7H2O) and alum (KAl(SO4)2·12H2O) as mordants. Effects of these mordants on color parameters (exhaustion (%), lightness (L∗), color axes (a∗ and b∗), hue angle (ho), color strength (K/S) and fastness properties evaluated) of MSL dyed cotton fabric were investigated. Flavonoids were identified as main chromophoric constituents in extracted MSL dye by UV–visible and Fourier transform infrared (FTIR) spectrophotometry techniques. Satisfactory color parameters in unmordanted MSL dyed fabric indicated that cotton fabric has a moderate affinity for the extracted dye. Metal pre-mordanting enhanced dye exhaustion by 4.85, 13.10 and 10% in Sodium chloride (Na+), ferrous sulfate (Fe2+) and alum (Al3+) dyed cotton fabrics respectively. Unmordanted MSL dyed fabric has lighter shade, higher L∗ and lower K/S value than metal salt pre-mordanted fabrics. The value of a∗ greater than b∗ and ho ​