Modulation of pomegranate peel colourant characteristics for textile dyeing using high energy radiations

The present study was concerned with extraction of natural colourants from pomegranate (Punica granatum L.) rind powder and characterization of extracted dye under the influence of gamma radiations. Both dyeing powder and silk fabric were exposed to different absorbed doses (20, 25, 30, 35 and 40 kGy) of high energy radiations using Cs-137 gamma irradiator. Aqueous, alkali and alcohol solubilized extracts were obtained from un-irradiated and irradiated pomegranate rind powders. Aluminium, copper, chromium and tannic acid (2-10% each) were employed to improve colour strength of extracted dye. Exposure of pomegranate peel colourant and silk fabric to gamma radiation greatly improved the extraction and dyeing process by reducing material to liquor ratio, dyeing time, dyeing temperature and salt concentration. Gamma ray treatments also had strong influence on colour strength and fastness characteristics of silk fabrics dyed with irradiated pomegranate peel. Gamma ray treatment of 40 kGy was the most effective dose for colourant extraction from pomegranate peel and surface modification of silk fabric. The good colour strength was obtained by dyeing silk with pomegranate peel fabrics at 50 °C for 40 min, keeping dye bath pH at 6.0 with salt concentration of 10 g/L. The result from mordanting experiments indicated that 10% of aluminium as pre-mordant and 10% of tannic acid as post-mordant were the best to enhance colour strength of extracted dye. It was also observed that gamma ray treated pomegranate rind had a good potential to alternate yellow and golden synthetic dyes in textile industry.