Cleaner production of disperse florescent dyes in supercritical CO2 and their applications in dyeing polyester fabric

Abstract

Supercritical carbon dioxide (scCO2) is commonly used as an excellent solvent in chemical reactions and dyeing fields because of its advantages. In this work, three coumarin and 1,8-naphthalimide fluorescent dyes (DAMC, NP-NH, and NP-dimethyl) were successfully constructed on the basis of the Au/titanium dioxide (Au/TiO2) catalytic reduction of nitro in scCO2 instead of SnCl2/hydrochloric acid solution, and their structures were confirmed correctly by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The cleaner synthesis and dyeing polyester fabrics of coumarin derivative (DAMC) in the presence or absence of N-methyl-pyrrolidone (NMP) were first studied by employing stepwise and synchronous methods. All results for DAMC indicated that the synchronous synthesis and dyeing method is more beneficial. Here, the synchronous synthesis and dyeing polyester fabrics of 1,8-naphthalimide derivatives (NP–NH and NP-dimethyl) in scCO2 were also investigated. Through the comprehensive analysis of color strength (K/S) value and fixation rate, the optimal temperatures and pressures of synthesis and dyeing for NP-NH and NP-dimethyl were obtained in the absence or presence of NMP. The dyed fabrics with NP-NH and NP-dimethyl exhibited yellow or yellowish-brown in daylight and bright fluorescent yellowish-green in ultraviolet light. All results showed that the clean production of fluorescent dyes (DAMC, NP-NH, and NP-dimethyl) can be realized by the hydrogenation of nitro with efficient Au/TiO2 catalyst in scCO2, meanwhile, the synchronous synthesis and dyeing method was proposed for the synthesized dyes. The realization of synchronous synthesis and dyeing fabrics for fluorescent dyes in scCO2 is an effective way to prevent environment pollution brought by the processes of synthesis and dyeing. Thus, the constructing and dyeing strategy of fluorescent dyes will be beneficial to the sustainable development of environment.