Clean fixation of dye on cotton in supercritical carbon dioxide with a heterogeneous and phase transfer catalytic reaction

A clean fixation of disperse reactive dye on cotton was investigated by employing a heterogeneous and phase transfer catalytical reaction with a phase transfer agent in a liquid-supercritical-solid triphase system, as an environmentally friendly alternative to conventional and heavy pollutional wet-chemical process. The catalytic fixation reaction was characterized by color intensity, fixation efficiency and Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). The results show that the dye fixation through a nucleophilic addition at a solid cellulosic polymer substrate phase could be effectively facilitated as the transportation of the anion of OH- or CO32- by the phase transfer catalyst of FC-134 from a liquid phase to supercritical phase and then onto the solid substrate in a self-built reactor. A heterogeneous and triphase transfer catalytic reaction mechanism was also supposed for the dye fixation at the solid substrate in supercritical carbon dioxide fluid with the presence of a base. (C) 2014 Elsevier Ltd. All rights reserved.