Effects of pre-treatment and microwave assisted extraction on natural dye from marigold (Tagetes erecta L.) and nasturtium (Tropiolum majus L.) for fabric colouration

Abstract

The present study demonstrated dyeing of silk and cotton fabric with the pigment extracted through various methods from two ornamentals, marigold (Tagetes erecta L.) and nasturtium (Tropeolum majus L.) Marigold creates the colour range from yellow to orange whereas for nasturtium off white to purple. The yield of extracted dye was found to be superior (6.24% and 4.48%) in pre-treatment of marigold and nasturtium petal respectively, with Ethanol 50% and under 6 min of microwave interval. To perform the dyeing process two different types of colourless mordants have been used viz. alum and stannous chloride. After scouring, mordanting and dyeing the fabrics were evaluated for colour measurements in HunterlabD25LT Chroma Meter for L* a* and b* values. The L* value were found to be superior when the fabrics were treated with alum. The highest L* value (85.78) was obtained in T15 i.e., pre-treatment of 70% HCl, 6 minute MW interval time and alum mordant in marigold. In nasturtium dyed silk fabric highest L*value (72.84) was found with the T16 treatment (70% EtOH + 6 min MW interval time + stannous chloride).The increased a* value was found with stannous chloride mordant. Through the strip test the tensile strength has been analysed. The highest streanth (412.16 g/m2 and 194.66 g/m2) was found in T1 (EtOH 50% + 4 min MW interval + alum) in marigold dyed silk and cotton fabric respectively. The stability of colour hue for the dyed sample after washing with standard soap with manual rubbing showed good in fastness properties and a little colour loss.