Effect of operational time on the chemical oxygen demand performance of sequencing batch reactor treating disperse dye synthetic wastewater

This work examines the effect of operational time of 6 hours on the removal of disperse dye from synthetic textile wastewater. Experiments were conducted daily at fill, react, settle, draw, and idle phase at 1 h, 1 h, 2 h, 1 h, 1 h respectively. The results showed that the highest removal efficiency of COD reached 77 %. Short operational time resulted in low COD removal efficiencies of disperse dye. The findings also revealed that when applying optimum operational time, sequencing batch reactor will achieve the highest growth of the bacteria responsible for the degradation of COD. When operational time increases, degradation becomes the dominant removal mechanisms of COD.

One-bath one-step dyeing of polyester/cotton (PC) blends fabric with disperse dyes after acetylation of cotton

Aiming at the classic problem of dyeing of polyester–cotton blended fabric one-bath one-step dyeing of PC blends with disperse dye after surface modification of cotton were studied. Surface modification of cotton was carried out using fibrous acetylation methods. The optimum value for surface modification was obtained with a concentration of acetylation agent 16% and time of reaction 2.5 h, gave a percent acetylation of 34. Surface chemistry and thermal decomposition were studied by using FTIR spectra and TGA. The tear strength crease recovery, pilling and abrasion resistance were evaluated. The experiment result of dyeing showed that the optimum value was obtained with dye concentration above 1% at a temperature of 120 °C warp tensile strength decreased by 12% and weft tensile strength was decreased by 9% from the control half-bleached fabric. Results of this study showed that one-step one bath dyed modified PC blend with disperse dye fabric presents good fastness property and color strength values compared with conventional two-bath dyed fabric.

Ultralow emission micro-printing process for PET fibers using liquid disperse dye

The commercial powder disperse dye used for printing polyester fabrics exhibits many environmentally-unfriendly properties, especially the associated high wastewater emission. In this study, three kinds of liquid disperse dyes (C.I. Disperse Blue 291:1, (L-DB); C.I. Disperse Red 179, (L-DR), and C.I. Disperse Orange 30, (L-DO)), two kinds of binders (A and/or B), and a micro-printing process, were applied to polyester fabric, with the goal of reducing freshwater consumption while maintaining color fastness. The influences of rheological and printing performance and color fastness were studied. Home-made liquid dyes of L-DB, L-DR and L-DO were found to exhibit higher color depth, excellent color fastness, and ultralow emission of wastewater and waste residual during the micro-printing process. The binder comprised of silicone-modified polyacrylate was observed to increase dye uptake, reduce dye sublimation, and improve color fastness. The liquid dyes of L-DB, L-DR and L-DO also exhibit stable and better rheological properties, which appeared to have little effect on the viscosity of printing pastes when compared with commercial powder disperse dye of Blue 3GFL (C.I. Disperse Blue 291:1), Red 2B (C.I. Disperse Red 179) and Yellow brown S-4RL (C.I. Disperse Orange 30), respectively. Results of this micro-printing process indicated that it is an environmentally clean production technology.

Energy Level and Chemical Class of Disperse Dyes—Plausible Characteristics of Level Dyeing Performance

The level dyeing index (LDI) is a measure of dye performance influenced by the dye migration process, ensuring the maximum uniformity of dye redistribution onto the fabric surface. The current study evaluates the level dyeing performance on polyester according to the energy level (low and high) and chemical classes (azo and anthraquinone based) of the three disperse dyes studied. The best levelness was obtained using C.I. Disperse Red 73 (an azo-based, low-energy level disperse dye), which exhibited the highest migration index (MI%) value. LDI results were obtained from the ratio of the exhaustion at the critical dyeing temperature (ECDT% and the final exhaustion Ef%), and the migration index (MI%). Each dye's LDI can be used to determine the compatibility of disperse dyes for combination dyeing.