Sustainable dyeing of denim using indigo dye recovered with polyvinylidene difluoride ultrafiltration membranes

Abstract

Indigo is one of the most consumed dyes in the textile sector, as it is widely used for the dyeing of denim clothes. About 15% of indigo used in the dyeing process is discharged to the wastewater treatment plants or sometimes into rivers, in countries where regulations are not strictly applied.In this work, real effluents that contained indigo dye were treated by means of 4 different ultrafiltration membranes. The feasibility to recover the concentrated dye with lab and semi-industrial pilots was also investigated. The studied membranes achieved up to 99% colour removal and 80% chemical oxygen demand (COD) decrease. Finally, the concentrates containing 20 g·L -1 of indigo dye were reused in new dyeing processes. Colour differences (DE cmc ) and rubbing and washing fastnesses were evaluated. Fabrics dyed with the recovered indigo concentrates exhibited similar characteristics than the ones obtained with the commercial dye.

Diffusion characteristics of dyeing in Polyester fiber garments referred to their mixtures with cotton and composition

“…Therefore, it is established that the higher the concentration, the lower the depletion rate, this process determines the phase matching influenced by the dye concentrations such as the standardization of the dyeing process and the mass isolation of the dye material, which are predominant in its solids (Vankar P. S., 2019), these characteristics are established by the conditions of the thermal gradients and the specific characteristics of the fiber and its diffusion. Some of the aspects that determine the dyeing process are the influence of volumes to be treated, the length of the dye molecule and the applied power, establishing the viability of the technology and the correct dyeing process as well as its fine quality (V. Buscio, 2015), another aspect is the temperature, since at a higher temperature the adequate diffusion of the migration of the dye molecules to be dispersed in the established fibers and the enzymatic digestion that determines the effectiveness in extracting the dyes and whose activity is established hydrolytic is determined by the complete digestion of the fibers (Paulina Góra, 2019). According to studies, it is established the importance of the thermal variable with temperatures of 120 and 130 °C depending on the type of fiber or the structure of the modified molecular fiber and its pairing, so the temperature must be increased in reference to the dyeing kinetics .…”

Efficient removal of Indigo dye from aqueous solution by an innovative method of emulsion liquid membrane

“…Among different colors being applied on Ajrak, blue is one of the prominent color usually achieved with Indigo dyes. Traditionally, this Indigo dye was of natural origin but its increasing demand and high cost of natural dyes has replaced it with synthetic Indigo dyes which are highly toxic, carcinogenic and mutagenic [2]. Ajrak industry also adopts the similar practice of disposing the untreated wastewater directly into surface water.…”

Treatment of a Textile Effluent by Electrochemical Oxidation and Coupled System Electooxidation–Salix babylonica

“…Treatment of textile dye effluent is difficult and ineffective with conventional processes because many synthetic dyes are very stable in light and high temperature, and they are also nonbiodegradable. Moreover, partial oxidation or reduction can generate very toxic byproducts [4][5][6].…”