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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.


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.


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 | Kechida M.,Textile Industrial Company SITEX | Mhenni M.F.,Research Unit of Applied Chemistry and Environment
International Journal of Environmental Research | Year: 2013

Textile Industries use different chemicals in indigo dyeing processes. Interest in eco-friendly processing in the textile industry has recently increased because of a larger awareness of environmental issues. For the case of indigo dyeing process, the reducing agent conventionally used is the - environmentally unfavourable - sodium dithionite, which will be replaced in this study with an ecological reducing agent called acetol that is also known as hydroxyacetone. In this paper, measurements of the redox potential at various experimental conditions were carried out in a dyeing bath, where acetol is the reducing agent of indigo. Moreover, an unconventional but eco-friendly indigo dyeing process of cotton was investigated. The effects of: reduction duration, dyeing duration, reduction temperature, alkalinity and the amount of indigo on the performances of this dyeing process were studied, and the dyeing results were evaluated by measuring the colour yield parameter (K/S) of the dyed samples at 660 nm. Finally, a factorial design was employed for the experimental plan; mathematical model equation and statistical analysis were derived by computer simulation applying the least squares method using Minitab 15.


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.


Haddar W.,Research Unit of Applied Chemistry and Environment | Baaka N.,Research Unit of Applied Chemistry and Environment | Meksi N.,Research Unit of Applied Chemistry and Environment | Meksi N.,Higher Institute of Fashion of Monastir | And 2 more authors.
Journal of Cleaner Production | Year: 2014

The olive oil industry releases considerable amounts of wastewater which contains huge reserves of natural dyes. Such wastewater could successfully be used for the dyeing of acrylic fibers. The influence of the main dyeing conditions (material/liquor ratio, dye bath pH, dyeing duration, dyeing temperature) on the performances of this dyeing process were studied. The dyeing performances of this process were appreciated by measuring the color yield (K/S) and the fastness properties of the dyed samples. A 24 full factorial design method was employed in order to study the interactions between the selected dyeing process parameters and to evaluate the optimal dyeing conditions. The optimization of these dyeing process factors to obtain maximum color yield was carried out by incorporating effect plots, normal probability plots, interaction plots, analysis of variance (ANOVA) and Pareto charts. A regression model was formulated using Minitab software and fitted the experimental data very well. In addition, it was found that dyeing of acrylic enables to reduce the concentration of polyphenols so that it reduced the Chemical oxygen demand COD. Furthermore, the biodegradability ratio (COD/BOD5) decreases but it was always superior to 3 which means that this aqueous waste still not biodegradable. It was also found that reusing the residual bath allowed to obtain a depth of shade very similar to the first dyeing and reduced considerably the environmental parameters (the concentration of polyphénols and COD). © 2013 Elsevier Ltd. All rights reserved.

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