Study of the hydrolysis kinetics of reactive dyes by capillary electrophoresis and optimisation of alkaline agent for the dyeing process

Abstract Understanding the hydrolysis behaviour of reactive dyes is critical for optimising dyeing processes, investigating hydrolysis kinetics and advancing sustainable textile technologies. Conventional analytical methods often fail to distinguish between multiple structurally similar dye forms, limiting kinetic studies. In this study, capillary electrophoresis was used to detect six dye forms of CI Reactive Orange 107 (RO107) and CI Reactive Yellow 201 (RY201). The hydrolysis behaviours were systematically evaluated under varying pH (8.0‐10.0), temperature (40‐70°C) and reaction time (0‐60 minutes). The varying concentrations of different forms indicated that RO107 and RY201 followed a pseudo‐first‐order reaction model, and the hydrolysis rates at 60°C were measured as 1.66 × 10 −2 and 1.64 × 10 −2 min −1 , respectively. Notably, the activated dye forms predominated at lower pH (9.0‐10.0) rather than at the conventionally applied value (pH 11.6) during dyeing. By Keeping hydrolysis below 13%, dye fixation was improved by 15%. Meanwhile, sodium carbonate (Na₂CO₃) dosage was reduced by 47% (from 15.0 to 8.0 g/L) without compromising colour strength. These findings provide a practical and sustainable approach to improving dye utilisation and reducing the environmental impact in textile dyeing.