Study of the cytotoxicity of reactive dyeing effluent treated by Fenton oxidation

Fenton oxidative wastewater treatment of CI Reactive Black 5 and CI Reactive Blue 19 effluent was performed after a simulated laboratory‐scale dyeing process, and the cytotoxicity of the treated effluent was evaluated using human skin cell lines. Among the components for Fenton oxidation, the human skin cell results showed that iron(II)sulfate at 150 mm did not show any significant cytotoxic effect, while other components, such as Glauber's salt solution (20 g l^?1; 14%), CI Reactive Black 5 (30 mg l^?1; 24%), caustic soda (5 g l^?1; 30%), CI Reactive Blue 19 (30 mg l^?1; 32%), hydrogen peroxide (0.01 m ) and soda ash (5 g l^?1) showed cytotoxic potential; the reagent sodium sulfite (30 mm ; 48%) exhibited the strongest cytotoxicity level. Fast decolorisation (>95%) was achieved within 10 min for CI Reactive Black 5, while for CI Reactive Blue 19 it took longer (1.5 h) to achieve the same decolorisation. Studies showed that decolorisation for both dyes followed second‐order kinetics. In spite of the remarkable efficacy of the Fenton oxidation process in removing colour within a short period of time, the resulting treated wastewater (within a reaction time of 1.5 h) also showed cytotoxicity towards the human HaCaT skin keratinocyte cell line. This observation can be explained by the strong oxidant and intermediate species produced during the advanced oxidation process, and a treatment step using sodium sulfite and a prolonged residence time can help to reduce the cytotoxicity.     

Electrochemical treatment of cotton textile-based dyeing effluent

The electrochemical treatment (ECT) of textile wastewater was carried out in a 1.5 dm³ electrolyte batch reactor using iron electrodes. With the four plate configurations, a current density (CD) of 89.2 A/m² and a pH value of 8.5 were found to be optimal, at which maximum reduction in chemical oxygen demand (COD) and colour achieved were 86% and 79%, respectively. Loss of 0.0666 kg/m³ iron electrode and 18.44 kWh/m³ power consumption was observed during ECT with a maximum COD reduction of 79%. The settling characteristics of electrochemically treated effluents as well as the characteristics of foam and residue were also analysed.     

Prediction of recipes for cotton cationisation and reactive dyeing to shade match conventionally dyed cotton

Cationisation allows cotton to be dyed with anionic dyestuffs (including anionic pigment dispersions) without the need for salt, and with decreased usage of dye, water, and energy. Appropriate cationisation levels play a part in dyeing properties such as fabric levelness, in fastness properties such as lightfastness, and in the overall cost of the cationisation treatment. The objective of this work is to assess whether it is possible simultaneously to predict a dye recipe and cationisation treatment level for cotton to yield a colourless or nearly colourless dyebath at the completion of the dyeing to match the shade of conventional fibre reactive dyeing of cotton. It has been shown that it is possible to model a cold pad batch cationisation process, relate the colour yield data and cationisation level for individual dyes, and finally predict a dyeing recipe and the required corresponding cationisation treatment to match the shade of conventional fibre reactive dyeing of cotton. The predicted dye recipe and cationisation amount yield colourless or nearly colourless dyebaths at the conclusion of the dyeing process.     

Chemical engineering aspects of reactive dyeing

The process of dyeing with reactive dyes was formulated on the basis of diffusion of dye species in the pores of polymer phase accompanied by fixation reaction with fiber substrate on the pore wall incorporating hydrolysis of dye species. The effect of the hydrolysis on the fractional fixation was numerically analyzed under various levels of bath ratio and degree of mixing in the dyebath. The simulation model was presented to yield the unlevelness arisen from lack of uniformity of degree of mixing in the dyebath.     

莫代尔纤维活性染料染深色探讨

本文选用了不同类型的活性染料，在不同浓度下对莫代尔纤维进行染色，分析了它们染色特性值的差异，并对纤维结构及染色性能进行了探讨，从而选出了哪类染料更适合莫代尔纤维染色。     

Concentration-dependent diffusion of dye in reactive dyeing systems

The cure of a tetrafunctional epoxy resin (largely tetraglycidyldiaminodiphenylmethane, TGDDM), cross-linked with diaminodiphenylsulphone (DDS) and boron trifluoride/ethylamine (BF₃EA) catalyst, is affected in a complex fashion by the presence of an oxidized carbon fiber surface. If the fiber is aged in a humid environment (25°C, 95% humidity) before coating with the matrix, the affinity of the oxidized fiber surface for water leads to destruction of the catalyst and retardation of the cure. This retardation is noticeable at lower humidities if the polymer content of the composite is reduced to > 20%. For oxidized fibers that are stored under ambient conditions (40% humidity), the retarding effect of water is overwhelmed by the catalytic effect of the acidic fiber surface. This activates the latent catalyst, increasing the rate of epoxy consumption and the proportion of the epoxy–epoxy reaction relative to the epoxy–amine reaction. For the low-humidity case, even though the rate of chemical reaction is increased, vitrification of the matrix is retarded, implying that there is less cross-linking and more extended epoxy–epoxy sequences in the network. The proposed chemical changes in epoxy/carbon fiber composites were confirmed by analysis of model reactions in solution. © 1992 John Wiley & Sons, Inc.     

Optimisation of the colour sequence in the process of fabric dyeing

When programming a dyeing machine, a sequence of colours has been established in an attempt to reduce the effects caused by dye residues on the colours that are subsequently applied. In this paper a model is presented that makes it possible to determine the optimum sequence. Using a optimisation method, the sequence that minimises the sum of the photocolorimetric differences between the colours required and those obtained has been determined. In order to estimate the change that each colour undergoes due to the presence of residual dye in the dyeing equipment a computer calculation method has been adopted.     

Improved reactive dyeing of wool with novel trifunctional reactive dyes†

The synthesis of a new trifunctional reactive dye is described in this paper by reaction of a di‐chloro‐s‐triazine dye with the specially synthesised amine, N,N’‐bis{2[(2‐chloroethyl)sulphonyl]ethyl}amine. When applied to wool from boiling dyebaths at pH 5, fixation efficiency values of 96% were recorded even at heavy depths (3% owf). In the case of the β‐chloroethyl sulphone group, there is good evidence that elimination to vinyl sulphone occurs readily in mildly acidic dyebaths at the boil. Since elimination is gradual, the reactive species does not form rapidly allowing migration and level dyeing to be achieved.     

Continuous dyeing of cationised cotton with reactive dyes

Cotton fabrics pretreated with cationic starch have been dyed with reactive dyes by a continuous dyeing method and the pretreatment conditions influencing dyeability of the treated cotton investigated. Cationised cotton has been found to give level dyeing without the presence of salt and dye fixation is improved compared with untreated cotton. The dyeings show good wash and rub fastness.     

Deep‐colour vat dyeing of cotton knit fabric on a modified jet dyeing machine

To improve the vat dyeing of cotton knit fabric with Indanthren Black RB Coll. (CI Vat Black 9), the basic parameters of dyeing, including the concentrations of chemicals, the dyeing temperature and duration, and the apparent diffusion coefficient of the dye, were obtained by test dyeing with a stoppered Erlenmeyer flask and the cellophane film roll method. A stable vat dyeing process has been developed on a modified jet dyeing machine for the first time without using nitrogen to purge oxygen. Modifications were made to improve the airtightness of the machine and the equipment in the liquor circulating system, with a water inlet and outlet for the gentle oxidation of dyed fabric, and with monitoring by means of a sensor inserted in the liquor circulating system for in situ measurements of the redox potential and the pH of the dyeing liquors. These measurements made it possible to follow to their completion the process of dyeing and the process of gentle oxidation by overflow washing with water and final oxidation. Optimal conditions with regard to the amount of reducing agent, the dyeing temperature (80 °C), and oxidising processes were established with this machine. It was found that, by using the modified machine and process conditions, dyeing proceeded stably and reproducibly (at 80 °C) to yield grade A dyed fabric. Visual inspection confirmed that faultless deep‐colour dyeing of the fabric was attained. Production has been proceeding successfully for the past 2 years. Owing to its insolubility, complete removal of the dye from the wastewater has been possible.     

Use of ultrasonic energy in reactive dyeing of cellulosic fabrics

The use of ultrasonic energy in dyeing cotton fabrics with monochlorotriazine and vinylsulphone reactive dyes has been studied spectrophotometrically. The dyeings carried out conventionally and by the use of ultrasonic techniques were compared in terms of percentage exhaustion, total amount of dye transferred to the washing bath after dyeing, fastness properties and colour values of the dyed materials. Overall results have shown that the use of ultrasound in reactive dyeing of cellulosic fabrics can result in energy savings, less water consumption, increased depth of colour and better process conditions.     

The dyeing of cotton with phosphonic reactive dyes in alcohols

The poor fixation achieved with phosphonated reactive dyes on cotton in practice, particularly in printing, has prompted a study of the effect of reaction conditions and the use of different diimides to achieve fixation. It has been possible to achieve as much as 95% fixation with a typical dye under suitable application conditions, where decomposition of the diimide can be minimised.     

Optimisation of the colour sequence in the dyeing process: industrial applications

In this paper we report, for realistic industrial work conditions, the applicability of the optimisation model developed to obtain the best colour sequence in the process of fabric dyeing. We have resolved the problem of ordering a long series of colours using a personal computer, to establish an optimum order. This takes into account the perceptual response of the human eye. The sequence begins with one specific colour, returning, under certain conditions, from dark to light colours. The algorithm we developed considerably reduces the number of determinations that must be carried out within a colorimeter.