Optimized production of Yellow 2G nanoparticles via supercritical gas anti-solvent process for advanced application in supercritical dyeing

Abstract

High-quality, efficient dye and pigment nanoparticles are ideal for supercritical dyeing in the textile industry, an eco-friendly and water-free dyeing method. This study investigates the precipitation of Yellow 2G nanoparticles, an azo dye, via the supercritical gas anti-solvent (GAS) process under varying pressures (10 MPa, 12.5 MPa, and 15 MPa), solute concentrations (0.1 mg.ml⁻¹, 0.3 mg.ml⁻¹, and 0.5 mg.ml⁻¹), and temperatures (308 K, 318 K, and 328 K), using the Box-Behnken design (BBD) approach. Results indicated that higher pressure, lower temperature, and reduced solute concentration favor the formation of uniform Yellow 2G nanoparticles. In this study, nanoparticles ranging from 168.8 nm to 760.8 nm were successfully generated, with 318 K, 15 MPa, and an initial concentration of 0.1 mg.ml⁻¹ identified as the optimal conditions. The features of the produced nanoparticles were assessed through HPLC, FESEM, XRD, DSC, and FTIR analyses. HPLC analysis confirmed the purity of the produced nanoparticles, while XRD and DSC results indicate a decrease in crystallinity and particle size. Additionally, FESEM observations verified that the precipitated dye particles were within the nano-scale range.