Green application of isolated colorant from neem bark for mordant-coated wool: Optimization of dyeing and mordanting for shade development

Abstract

This study aimed to assess the effectiveness of utilizing a tannin-based natural brown colorant from neem bark for dyeing wool under microwave treatment, specifically evaluating its coloring efficiency. The colorant was extracted in a methanol solution that had been acidified both before and after being subjected to microwave treatment for up to 6 min. The dyeing variables were optimized to create new shades of dye with desirable fastness properties, and sustainable chemical and bio-mordants ranging from 1 to 10 g/100 mL were employed. Through experimentation, it was determined that when an unirradiated acidic methanolic extract (AME) with a salt concentration of 3 g/100 mL was applied onto wool fabric (RWF) and subjected to microwave treatment for 4 min, it resulted in a high color yield. This was achieved by heating the solution to 65 °C and allowing it to remain in contact with the fabric for a duration of 65 min. Favorable color characteristics were achieved when utilizing a pre-chemical mordant of 5% Fe and a post-chemical mordant of 5% Fe. In contrast, the utilization of 7% henna as a pre-bio-mordant in combination with 3% turmeric extract as a meta-bio-mordant resulted in favorable color characteristics. The study concludes that microwave treatment exhibits outstanding sustainable efficacy in isolating colorants from neem bark powder for wool dyeing. Incorporating bio-mordants further enhanced the process’s sustainability and eco-friendliness.