The textile industry uses the electrochemical techniques both in textile processes (such as manufacturing fibers, dyeing processes, and decolorizing fabrics) and in wastewaters treatments (color removal). Electrochemical reduction reactions are mostly used in sulfur and vat dyeing, but in some cases, they are applied to effluents discoloration. However, the main applications of electrochemical treatments in the textile sector are based on oxidation reactions. Most of electrochemical oxidation processes involve indirect reactions which imply the generation of hypochlorite or hydroxyl radical in situ. These electrogenerated species are able to bleach indigo-dyed denim fabrics and to degrade dyes in wastewater in order to achieve the effluent color removal. The aim of this paper is to review the electrochemical techniques applied to textile industry. In particular, they are an efficient method to remove color of textile effluents. The reuse of the discolored effluent is possible, which implies an important saving of salt and water (i.e., by means of the “UVEC Cell”).

In this work, the efficiency of a photo-electrochemical method to remove color in textile dyeing effluents is discussed. The decolorization of a synthetic effluent containing a bi-functional reactive dye was carried out by applying an electrochemical treatment at different intensities (2 A, 5 A and 10 A), followed by ultraviolet irradiation. The combination of both treatments was optimized. The final percentage of effluent decolorization, the reduction of halogenated organic volatile compound and the total organic carbon removal were the determinant factors in the selection of the best treatment conditions. The optimized method was applied to the treatment of nine simulated dyeing effluents prepared with different reactive dyes in order to compare the behavior of mono, bi, and tri-reactive dyes. Finally, the nine treated effluents were reused in new dyeing processes and the color differences (DECMC (2:1)) with respect to a reference were evaluated. The influence of the effluent organic matter removal on the color differences was also studied. The reuse of the treated effluents provides satisfactory dyeing results, and an important reduction in water consumption and salt discharge is achieved.

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La lengua (y la escritura) es el vehículo de la mayor parte de interacciones que ocurren en nuestra vida social. Por ello es hacedora, instrumento de comunicación y recurso implícito y/o explícito de las relaciones sociales, y como tal, también del Capital social. En un colectivo fuertemente cohesivo, en el sentido de gran intensidad de relaciones fuertes internas al mismo en un ámbito dado de la vida social, se puede suponer que la lengua de uso y referencia en dicho ámbito es idéntica en otros ámbitos si el mismo grupo permanece también cohesivo en ellos. Visto a la inversa, el hecho de que en un colectivo se den y usen dos o más lenguas diferentes, desconocidas o con competencias limitadas por partes de dicho colectivo, no facilita la cohesión global del grupo y sí la formación de grupos cohesivos por comunidades lingüísticas. En el caso de la integración, esto es, de relaciones de un colectivo con otros colectivos, identificados como diferentes a través de otros rasgos que no la lengua, se puede suponer que la existencia de una misma lengua de uso y referencia es un mecanismo facilitador, aunque no determinante, de la integración del colectivo en la totalidad de dichos colectivos. Lo que afirma y trata de explorar este articulo, para distintos colectivos en Catalunya, es por un lado, que la lengua de un colectivo puede ser un factor de homofilia que facilite tanto la cohesión interna como la integración con otros colectivos con la misma lengua. Y por otro lado, que el uso de distintas lenguas no facilita dicha integración en y con los colectivos identificados por otras características. Palabras clave: Cohesión social-Integración social-Lengua de uso y referencia-comunidad de habla. 1 Este artículo se basa en la investigación cuya referencia es CSO2008-01470, subvencionada por el Ministerio de Educación y Ciencia en el marco del VI Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011. Los autores de este artículo pertenecen a dicho proyecto.

An electrochemical treatment (EC) was applied at different intensities to degrade the chromophoric groups of dyes C.I. Reactive Black 5 (RB5) and C.I. Reactive Blue 7 (Rb7) until uncolored species were obtained. Decolorization rate constants of the azo dye RB5 were higher than the phtalocyanine Rb7 ones. In addition, the EC treatment was more efficient at higher intensities, but these conditions significantly increased the generation of undesirable by-products such as chloroform. The combination of EC with UV irradiation (UVEC) drastically minimized the generation of chloroform. The photo-assisted electrochemical treatment was also able to achieve decolorization values of 99%. Finally, mixtures of dyes and surfactants were treated by EC and UVEC. In the presence of surfactants, the decolorization kinetic of dyes was slowed due to the competitive reactions of surfactants degradation. Both methods achieved total decolorization and in both cases, the generation of haloforms was negligible.

Electrochemical techniques offer many advantages for the treatment of industrial effluents. These processes are clean, operate at room temperature, and in most cases, do not need the addition of reagents (as in the case of reactive dyeing effluents). In particular, the electrochemical treatment of textile effluents is an efficient method to remove colour. In this work, diverse synthetic effluents containing reactive dyes were treated in an electrochemical cell with Ti/PtO x electrodes. The efficiency of the process to remove colour and the use of an additional UV irradiation were evaluated. Once the conditions were established in synthetic effluents, they were applied on two types of exhausted reactive dye baths collected from a cotton mill. Instead of the effluent discharge, another possibility is to reuse the decoloured effluents for a new dyeing process. In this sense, diverse experiments were carried out and conditions for the effluents reuse were established. The reuse of dyeing effluents implies an important reduction of the salt and water consumption as well as a reduction of the salinity of the discharged effluents.Postprint (published version

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