Fabrication of Bio-Colored and Functional Wool Using Natural Pu’er Tea Extract

Applying synthetic dyes in textile dyeing may lead to severe environmental pollution due to liquid waste emissions; therefore, it is urgent to develop environmentally-friendly ecological dyes to minimize such damage. By using Pu’er tea extract (PTE) as a natural colorant to dye wool, this study created such bio-colored material in experiments, during which the thermal stability and antibacterial activity of wool both with and without PTE dyeing were also explored. Most importantly, it is proved that the dyed wool can deliver better color depth and fastness, with the dyeing ability considerably improved after ferrous sulfate (FeSO4·7H2O) mordant treatment as well. Furthermore, the inhibition rate of wool against Escherichia coli (E. coli) could reach 88.02 % and 90.25 % for direct dyeing and mordant dyeing, respectively, at a PTE concentration of 60 g/L, while the antibacterial rate remains above 70 % after 10 washing cycles of accelerated laundering. Another important phenomenon observed is that the thermal decomposition temperature of the wool dyed with PTE was increased, demonstrating that PTE, as a natural colorant, could improve the thermal stability of wool, in addition to stable dyeing properties.