Enhancing the fastness characteristics of weld‐dyed cotton and recycled nylon 6,6 fabrics via sodium alginate and titanium dioxide

Abstract This study investigates a sustainable dyeing and finishing strategy for recycled nylon 6,6 and organic cotton fabrics dyed with weld. Following meta‐mordant dyeing using alum under Natural Organic Dye Standard (NODS)‐compliant conditions, the fabrics were subjected to functional finishing with titanium dioxide as a multifunctional photocatalytic surface agent and sodium alginate as a film‐forming biopolymeric binder. The finishing process was optimised using pad‐batch and exhaust procedures, with parameters varying with the TiO 2 /C 6 H 7 NaO 6 concentration ratio. Fourier transform infrared (FTIR) spectroscopy was employed to investigate the structural properties of the dyed fabrics and determine the molecular‐level interactions between titanium, sodium alginate and the fibre matrix. Surface elemental distribution was analysed using scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM‐EDX). Natural dye components were identified by high‐performance liquid chromatography with diode‐array detection (HPLC‐DAD) under fully reported, reproducible chromatographic conditions. The results indicate that the alginate‐based coating improves dye fixation and fastness by forming a continuous surface film, while TiO 2 enhances UV protection primarily through scattering and absorption mechanisms, thereby significantly decreasing the transmission level of UV‐A and UV‐B radiation.