Optimization and assessment on indirect electrochemical reduction of indigo

Abstract

Purpose An indirect electrochemical reduction and dyeing with indigo were carried out here to solve problems of low dye reduction rate and poor dyeing depth in the current electrochemical dyeing process. Design/methodology/approach Response surface analysis tests were performed to evaluate the effects of ferrous sulfate concentration, medium concentration, sodium hydroxide concentration and reduction time on the reduction efficiency of indirect electrochemical reduction of indigo. Findings The conditions obtained by design-expert optimization showed that the concentration of FeSO4·7H2O has the most significant effect on the reduction performance of dye liquor. Under the optimized electrochemical reduction dyeing process, the rate of dye reduction could be reached 91.21 per cent and the K/S value of indirect electrochemical dyeing of indigo can be achieved to 12.96, which is increased by about 9.56 per cent compared with that of Na2S2O4 dyeing with the same color fastness basically. Research limitations/implications The recyclability and biodegradability of the dye remain to be explored. Practical implications The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production. Social implications The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production. Originality/value Application of the Fe(II)-DGS-Abal B complex media system in the indirect electrochemical reduction of indigo.

Critical Review on Sustainability in Denim: A Step toward Sustainable Production and Consumption of Denim

“…In the direct electrochemical dyeing process, the indigo dyes are reduced directly; nevertheless, a small amount of conventional reducing agent is required to reduce the dyes to establish the chemical reaction; once the reaction has begun, the electrochemical reaction may be continued. Alternative electrochemical approaches for the reduction process may be the best solution to boost the eco-efficiency of current dyeing procedures for indigo dyeing on denim. , It minimizes a number of chemicals used in the reduction process . The use of an ultrasonic system to perform electrochemical reduction on indigo dyes increases the water solubility followed by the dyeing efficiency, ensuring the environmentally friendly dyeing of denim under an aqueous system. , The indigo dye particle size is reduced due to the ultrasonic atmosphere, and it is increasing the water solubility.…”

“… 61 , 62 It minimizes a number of chemicals used in the reduction process. 63 The use of an ultrasonic system to perform electrochemical reduction on indigo dyes increases the water solubility followed by the dyeing efficiency, ensuring the environmentally friendly dyeing of denim under an aqueous system. 64 , 65 The indigo dye particle size is reduced due to the ultrasonic atmosphere, and it is increasing the water solubility.…”

Vat Dye Molecule–Proton Dual Adsorption Catalysis Based on Molybdenum Disulfide for Sustainable Textile Dyeing

“…Utilizing high surface area catalysts to facilitate electron transfer in electrochemical reduction is a promising strategy that has been successfully applied to numerous organic reactions. − In the context of indigo dye reduction, the molecular indigo (C 16 H 10 N 2 O 2 ) undergoes electron transfer reactions to convert into its soluble reduced form, leuco-indigo. − This process involves the reduction of double bonds and heterocyclic structures within the indigo molecule. In electrochemical methods, active hydrogen (or protons) are generated through the electrocatalytic process using water as the proton donor, providing a green and sustainable pathway for indigo dye reduction. , However, the crux of this technology lies in the precise control of active hydrogen generation during the hydrogen evolution reaction (HER) and the coadsorption of indigo molecules on the catalyst surface.…”

Electrochemical Dyeing of Cotton Fiber for Environmental Protection

“…However, due to the complex operation process, poor levelness, high cost and other shortcomings, these technologies can only be explored in the laboratory, but far from the large-scale use of industrialization. The electrochemical salt free dyeing technology has many advantages, such as easy control, mild reaction conditions, little damage to fiber, energy saving and emission reduction, simple operation, excellent dyeing effect and environment-friendly [11][12][13][14][15][16][17][18][19][20].…”