Solvent-mediated extraction of disperse dyes from polyester: correlating Cyrene extraction yields with molecular topological and chemical descriptors

Abstract

The desorption of disperse dyes from synthetic textiles remains a critical challenge in sustainable textile processing, particularly when targeting structurally diverse dye classes. This study examines the structure–property relationships governing solvent-mediated dye extraction using Cyrene™, focusing on azo and anthraquinone systems. Dye removal was conducted over three successive cycles under optimised conditions. Statistical analysis (ANOVA and Tukey's HSD) revealed that dye type, cycle number, and their interaction significantly influenced removal efficiency. Three of the four dyes exhibited statistically similar mean reductions, while CI Disperse Blue 56 (DB), the most planar and least topologically complex, showed the lowest efficiency. Topological descriptors derived from ChemDraw and Chem3D modelling identified DB as the smallest in molecular dimensions, whereas CI Disperse Red 60, CI Disperse Yellow 114, and CI Disperse Orange 30 were more structurally intricate. Correlation analyses (Pearson's and Spearman's) yielded limited predictive relationships, though descriptors such as log P and log S showed relatively higher coefficients. Despite the absence of definitive correlations, dyes with greater surface area and molecular complexity demonstrated enhanced interaction with Cyrene™, achieving up to 98.5% colour reduction. These findings underscore the robustness of the developed method and suggest that molecular architecture plays a contributory role in solvent–dye interactions under controlled conditions.