Performance of anode materials in electrochemical treatment system for indigo dyeing wastewater

Purpose This study aims to explore suitable anode materials used in the electrochemical system for indigo dyeing wastewater, to achieve optimal treatment performances. Design/methodology/approach The single factor experiment was used to explore the optimum process parameters for electrochemical decolorization of indigo dyeing wastewater by changing the applied voltage, electrolysis time and electrolyte concentration. At the voltage of 9 V, the morphology of flocs with different electrolytic times was observed and the effect of electrolyte concentration on decolorization rate in two electrolyte systems was also investigated. Further analysis of chemical oxygen demand (COD) removal rate, anode weight loss and sediment quantity after electrochemical treatment of indigo dyeing wastewater were carried out. Findings Comprehensive considering the decolorization degree and COD removal rate of the wastewater, the aluminum electrode showed the best treatment effect among several common anode materials. With aluminum electrode as an anode, under conditions of applied voltage of 9 V, electrolysis time of 40 min and sodium sulfate concentration of 6 g/L, the decolorization percentage obtained was of 94.59% and the COD removal rate reached at 84.53%. Research limitations/implications In the electrochemical treatment of indigo dyeing wastewater, the aluminum electrode was found as an ideal anode material, which provided a reference for the choice of anodes. The electrodes used in this study were homogenous material and the composite material anode needed to be further researched. Practical implications It provided an effective and practical anode material choice for electrochemical degradation of indigo dyeing wastewater. Originality/value Combined with the influence of applied voltage, electrolysis time and electrolyte concentration and anode materials on decolorization degree and COD removal rate of indigo dyeing wastewater, providing a better electrochemical treatment system for dyehouse effluent.

A Study on Sustainable Design for Indigo Dyeing Color in the Visual Aspect of Clothing

Various colors of clothing originating from synthetic dyes are presently causing serious environmental pollution problems, whereas natural dyes extracted from indigo plants help to reduce harm to the environment and extend the sustainable use of clothing. This study focuses on the difference between indigo dyeing colors and the environment on the basis of sustainable design. This study surveyed 105 postgraduates and college students through repeated measurements of ANOVA. The results reveal that light colors are considered to conform to the sustainable spirit more than dark colors in different indigo shades. In fact, a recyclable light-colored indigo-dyed t-shirt is beneficial due to its reusability. Indigo-dyed fabric can be decomposed by a variety of microorganisms; however, light-colored indigo dyeing takes a shorter amount of time. Light-colored indigo dyeing is more resource-saving when considering dye, water and electricity costs. The results of the relationship between colors and environmental protection provide scheme references to consumers or industries for clothing collocation of different indigo dyeing colors for a series of blue clothing, and carry out the idea of sustainability and co-existence between clothing and natural resources.

A Study on Sustainable Design for Indigo Dyeing Color in the Visual Aspect of Clothing

Various colors of clothing originating from synthetic dyes are presently causing serious environmental pollution problems, whereas natural dyes extracted from natural indigo plants help reduce the harm to the environment and extend the sustainable use of clothing. This study focuses on the relation between indigo dyeing colors and the environment on the basis of sustainable design. The results reveal that light colors are considered to conform to the sustainable spirit more than dark colors in different indigo colors. In fact, the recyclable light-colored indigo dyeing t-shirt is beneficial in its reuse. Indigo dyeing fabric can be decomposed by a variety of microorganisms; however, the light-colored indigo dyeing takes a short time. Light colored indigo dyeing is more resource-saving when considering dye, water and electricity costs. The results of colors and environmental protection provide scheme references to consumers or industry for clothing collocation of different indigo dyeing colors for a series of blue clothing and carry out the ideal of the sustainability and co-existence between clothing and natural resources.

Environment-friendly nanocellulose-indigo dyeing of textiles

Dyeing of one pair of denim blue jeans consumes about 50-100 liters of water loaded with toxic reducing agents and alkali that remain effluent in wastewater. Here we introduce environmentally...

Indigo Dyeing of Cotton using Alkaline Catalase and Additives

Sodium hydrosulfite is universally applied as a reducing agent for the reduction of indigo, but also produces hazardous by-products viz. sulfate, sulfite, and thiosulfate ions with harmful effects on the environment due to their toxicity, as well as corrosive effects on the waste lines. To overcome these problems, use of an ecofriendly reducing agent, viz. alkaline catalase, along with iron (II) sulfate, was used in place of sodium hydrosulfite for dyeing of cotton with indigo. Dyed samples were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The alkaline catalase with iron (II) sulfate reducing system produced the same reduction potential in dyebaths, reduction bath stability, surface color strength, and color fastness properties of dyed cotton compared to sodium hydrosulfite use.

Sustainable Indigo Dyeing and Fixation Mechanism of Wet Rubbing Fastness Agent on Cotton Fiber in Silicone Non-Aqueous Dyeing System

Indigo dyeing of cotton fiber in the silicone non-aqueous medium dyeing system was investigated to avoid the multiple dyeing of cotton yarn or fabric, high environmental pollution, and the need for multiple washing and sand washing. After fixing, the rubbing fastness of dyed fiber could be improved to 3–4 grade and the washing fastness increased 1–2 levels. The mechanism of rubbing fastness agents was also studied. Most of the wet rubbing fastness agents for indigo dyeing were waterborne polyurethanes. After fixation, a film was formed on the fiber surface. Moreover, the rubbing fastness was improved by the electrostatic interaction between the cellulosic fiber and indigo after treating with fixing agent. Indigo dyeing of cotton fiber was possible in the silicone non-aqueous dyeing system.