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Ticha1 M.B.,Research Unity of Applied Chemistry and Environment | Meksi N.,Research Unity of Applied Chemistry and Environment | Meksi N.,Higher Institute of Fashion of Monastir | Drira N.,Research Unity of Applied Chemistry and Environment | And 2 more authors.
Chemical Industry and Chemical Engineering Quarterly | Year: 2014

Textile industries use different chemicals in dyeing processes, consuming large quantities of water and producing large volumes of wastewater. For the particular case of indigo dyeing processes, its reduction is performed chemically by the addition of sodium dithionite. However, this is considered environmentally unfavorable because of the resulting contaminated wastewaters. Therefore, it is important to replace sodium dithionite with other alternatives in order to achieve cleaner processes. -hydroxycarbonyls have been suggested as possible environmentally friendly alternatives to reduce indigo. However, each one applied alone is unable to attain the dyeing performances offered by the conventional reductant. Thus, the study of the synergy of some selected α-hydroxycarbonyls was proposed. In this paper, a mixture design of experimental (DOE) methods was used to determine the optimum combination of α-hydroxycarbonyls to be applied in the indigo reduction process. Based on the design expert software, quadratic models were established as functions of -hydroxycarbonyls ratios. The diagnostics of models were investigated by using mixture contour plots. Finally, a model was proposed to predict the optimum conditions leading to dyeing performances exceeding those obtained from the reduction of indigo by the conventional sodium dithionite. ©2014 CI and CEQ. All rights reserved. Source


Meksi N.,Research Unit of Applied Chemistry and Environment | Meksi N.,Higher Institute of Fashion of Monastir | Ben Ticha M.,Research Unit of Applied Chemistry and Environment | Kechida M.,Societe Industrielle des Textiles SITEX | Mhenni M.F.,Research Unit of Applied Chemistry and Environment
Journal of Cleaner Production | Year: 2012

Nowadays, in most indigo dyeing processes the reduction step is performed chemically by sodium dithionite. This is considered environmentally unfavourable because of the resultant contaminated wastewaters. So, there has been interest to find new possibilities which would be ecologically more attractive to reduce indigo. In this paper, a comparison between sodium dithionite and some ecofriendly α-hydroxycarbonyls was effectuated. The examples of glucose (such as an α-hydroxyaldehyde), acetol and acetoin (such as an α-hydroxycetone) were treated. This comparison was based on redox potential measurements taken in absence and in presence of indigo under several conditions of temperatures, molar concentrations of studied reducing agents and sodium hydroxide. A thermodynamic study was also released in order to evaluate more precisely the reducing properties of each reductant by calculating the equilibrium constant of reduction reaction "Kr". The dyeing performances resulted from the reduction of indigo by each one of the studied reducing agents were appreciated by measuring the colour yield (K/S). The obtained results showed that α-hydroxycarbonyls could offer an environmentally safe alternative to sodium dithionite as a reducing agent in indigo dyeing processes. © 2011 Elsevier Ltd. All rights reserved. Source


Meksi N.,Research Unit of Applied Chemistry and Environment | Meksi N.,Higher Institute of Fashion of Monastir | Ben Ticha M.,Research Unit of Applied Chemistry and Environment | Kechida M.,Societe Industrielle des Textiles SITEX | Mhenni M.F.,Research Unit of Applied Chemistry and Environment
Industrial and Engineering Chemistry Research | Year: 2010

In the borohydride dyeing process, indigo cannot be reduced by sodium borohydride to its reduced form without the addition of catalyst. This catalyst, which is a metallic salt, is used to activate the reduction procedure of the reducing agent. So, the reduction reaction of indigo depends significantly on the nature of this catalyst. In this paper, the effect of 12 different metallic salts on the performances of the indigo reduction reaction has been discussed. These performances were evaluated by measuring the indigo reduction yield as well as the color yield (K/S) of the dyed samples of cotton. In these studies, it was found that the copper-based catalysts were the best and offered maximum performance. © 2010 American Chemical Society. Source


Ben Ticha M.,Research Unit of Applied Chemistry and Environment | Meksi N.,Research Unit of Applied Chemistry and Environment | Meksi N.,Higher Institute of Fashion of Monastir | Drira N.,Research Unit of Applied Chemistry and Environment | And 2 more authors.
Industrial Crops and Products | Year: 2013

The present paper investigates a non conventional but eco-friendly exhaust dyeing process of cotton with indigo. During this process, indigo was converted to its water-soluble leuco form by a green reducing agent: the glucose, in presence of alkali and at high temperature. To improve the exhaust dyeing process, the dyeing step was carried out on modified cotton by several cationizing agents. Modified cotton fibres were characterized by Fourier transform infrared (FTIR) spectra and an X-ray diffraction analysis. The performances of the dyeing process were evaluated by measuring the bath exhaustion E (%), the colour yield (K/. S), the brightness index BI (%) and the dyeing fastnesses of the coloured cotton. It was found that the colour yield and the brightness obtained from the exhaustion dyeing were improved when using cationized cotton giving fastness properties better than those obtained with untreated cotton dyed by the conventional process. The effect of the main operating conditions (cationizing agent nature and concentration, reducing temperature, dyeing duration, dyeing temperature) on the quality of this dyeing process were also studied. A surface design was employed for experimental design and optimization of results. Mathematical model equation and statistical analysis were derived by computer simulation programming applying the least squares method using Minitab 15. © 2013 Elsevier B.V. Source

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