Search

The textile industry generates large volumes of waste throughout its production process. Most of this waste is colored, therefore, discoloration is an important step toward recycling and reusing this waste. This study focused on the chemical reductive discoloration of textile waste composed of cotton dyed with reactive dye. The experimental design demonstrated the significant influence of the concentration of reducing agent and time of reaction on the degree of whiteness of the cotton fibers. The concentration of the alkaline agent was not significant in the process. The optimization of the reaction conditions lead to Berger degree of 50.5 ± 3.5. The discolored cotton was chemically recycled through dissolution in ionic liquid 1-ethyl-3-methylimidazolium chloride and regeneration in film form in water. The microstructure of the regenerated cellulose films was evaluated by Scanning Electron Microscopy (SEM) indicating complete dissolution and uniform regeneration. The discoloration process reduced the polymerization degree and crystallinity index of the cotton fibers but retained the cellulose I structure. The dissolution and cellulose regeneration process results in transparent films with an amorphous structure. The thermal behavior, evaluated by thermogravimetric analysis, indicated that residues and regenerated film presented a main decomposition step. The maximum decomposition rate temperature of the regenerated films was approximately 40°C lower than the cotton fibers, which correlates well with the reduction in polymerization degree and amorphous structure. In general, the study demonstrated that textile cotton waste dyed with reactive dyes can be chemically discolored to form transparent and amorphous films, contributing to the development of sustainable strategies for the textile industry. [ABSTRACT FROM AUTHOR]

The current study reports the results of non‐aqueous dyeing on polyamide fabrics based on a reverse micellar system composed of a stable emulsion of soybean oil, a co‐surfactant, a nonionic surfactant and acid dyes. The system does not make use of water or electrolytes and significantly reduces the dyebath volume. The influence of the hydrophilic lipophilic balance of the surfactants was evaluated, and it was found that the more hydrophilic the surfactant, the better the interaction of the reverse micellar emulsion with the substrate and, consequently, the greater the resulting colour strength. The co‐surfactant plays an important role in the system, as its proportion to the surfactant/oil mixture is directly related to better exhaustion of the dyebath. The results were compared with those from a conventional water‐based dyeing system. Colour matching was performed using the CIELab colour difference formula (ΔE) measured by a reflectance spectrophotometer. [ABSTRACT FROM AUTHOR]

The textile industry can benefit from the use of microcapsules, both adding value to products through the production of technical or functional textiles and improving the processes in the production chain. Some applications have been widely explored in academic research, but many are not feasible for use in industrial scale. Thus, the aim of this study was to develop consistent and efficient methodologies for the encapsulation of active compounds commonly used in the textile industry, employing materials which are viable for large-scale application. In this study, polyurethane-urea microcapsules were formulated by interfacial polymerization and encapsulated with C.I Disperse Blue 60 for the dyeing of polyester fabric without the use of dispersing agents and other auxiliaries. The dyeing was carried out in a high temperature dyeing machine with a very simple dyebath, in which there are only dissolved dye molecules, microencapsulated dyes and the fabric. Additionally, the dyebath wastewaters were reused on a further dyeing as 100% bathwater and mixed with 50% distilled water. Colorimetric measurements show excellent colour removal in both samples. [ABSTRACT FROM AUTHOR]

This paper presents results of a modelling study on the separation of ethane/ethylene mixture by selective adsorption on zeolite 13X in a simulated moving bed (SMB) unit. Propane and n-butane are evaluated as desorbent candidates. The study encompasses molecular simulation calculations for determination of adsorption parameters, whose results will then be used in a mathematical model for evaluating the performance of an SMB unit. This work is entirely done in silico, by using available force field parameters for the molecular simulations part and reliable mathematical models for the SMB part. Experimental data are solely used for comparison with the molecular simulation results, which are subsequently expanded to calculate adsorption properties for separating the mixtures, without further experimental work. The separation regions of an SMB unit operating with zeolite 13X for ethane/ethylene separation, using propane and n-butane as desorbents, were obtained by simulation at 110 kPa and at four different temperatures: 298, 323, 348 and 373 K. For each desorbent, an operating point was selected, and the size of the required unit was presented for the complete separation of the two components of the mixture. [ABSTRACT FROM AUTHOR]