Sodium Lignosulfonate: an Industrial Bio-Waste for the Colouration and UV Protective Finish of Nylon Fabric

Sodium lignosulfonate (NLS), a biomass waste procured from paper and pulp industries as brown colour water soluble powder, is explored in this article as dye for nylon 6 fabrics in aqueous media by the exhaustion method. The fastness and functional properties of the dyed nylon 6 fabrics were studied. The dyeing process parameters were optimised using Box–Behnken response surface design and the ANOVA technique. The NLS treated dyed nylon fabric exhibited an excellent ultraviolet protection factor (UPF), as high as 62.13. The NLS dyed nylon fabrics were characterised using FTIR, FESEM, EDX and instruments. The ultraviolet protection factor (UPF) and colour strength (K/S) values are significantly increased with an increase in the concentration of NLS without any loss of tensile properties and thermal stability. Moreover, NLS treatment has excellent wash fastness. This dyeing process for synthetic fibre like nylon can be a cleaner and more eco-friendly approach by utilising waste biomass of paper from the pulp industries.