Ecofriendly hair dye extraction from wastewater pericarp processing by-products of water caltrop (Trapa quadrispinosa): Optimization and evaluation

Abstract

As an alternative approach for toxicological effects of synthetic hair dyes, water caltrop (Trapa quadrispinosa) pericarp pigment extracted by 50% ethanol at 40 °C for 30 min was used as an ecofriendly and natural hair dye. Water caltrop pericarp (WCP) of seven regions were experimented to develop eco-friendly dyes intended for application in alternative chemical synthesis hair dyeing products. The results showed that the highest content of polyphenol was extracted from WCP in Jiaxing, which was used as a follow-up study. The optimization method was mordant dyeing first and then dyeing. Optimal dyeing conditions were identified as 4% Fe3+ at 25 °C with a total dyeing time of 65 min, and WCP hair dye showed better resistance to washing. The results of SEM and DSC showed that WCP hair dye could replace synthetic hair dyes and has some restorative function for damaged hair. This study provides a valuable reference for the development of more environmentally friendly hair dyes.