Extraction and Application of Pumpkin Peel Colorants for Natural Textile Dyeing

This preliminary research discusses the extraction of colorants from pumpkin peel as vegetable dyes and the potential dyeing capability of silk and cotton fabrics. For pumpkin extracts, thermal gravity analysis has verified the range of temperature for application, while a combination of UV–vis spectra and high-performance liquid chromatography analysis confirmed the main colored components and structural characteristics. It was found that the extracts of this vegetable dye have excellent thermal stability as well as stability in neutral and acid conditions. With the objective of achieving the greatest absorbency rate of extracted solution, the following optimum extraction conditions were obtained: 100% ethanol, an extraction temperature of 70°C, an extraction time of 60 min, and a material-to-liquor ratio of 1:10. To attain the highest dyeing uptake rate and K/S values, the optimum dyeing profiles with meta-mordanting for silk fabrics were found to be 95°C, 90 min, pH 5.5, and a liquid ratio of 1:60. The optimum dyeing profiles with meta-mordanting for cotton fabrics were 95°C, 90 min, and a liquid ratio of 1:60. Nearly all colorfastness results for silk and cotton fabrics met the basic requirement of the China National Standard, except a few.