The presence of aromatic amines in effluent from dyeing processes of the textile industry is an added\ud
problem to the high coloration typical of this type of effluent. The main objective of the present work was to\ud
eliminate these two problems simultaneously by electrochemical treatment using bath solutions containing\ud
three azo dyes. For the analysis of amines, a liquid–liquid extraction method was developed as an easier and\ud
faster alternative to the method described in the standards and widely used in analytical laboratories. Four\ud
amines (aniline, o-toluidine, 4-chloroaniline and 4-aminobiphenyl) were detected by GC-MS in the residual\ud
azo dye baths. A total amine concentration of between 2.5 and 1 ppm was detected, 4-aminobiphenyl being\ud
the main compound. Both residual colour and amines were removed by electrochemical treatment carried\ud
out at three current densities (3, 24 and 40 mA/cm2). At 24 mA/cm2, more than 90% of colour removal was\ud
achieved, and the total amine concentration was reduced to below 0.15 ppm.Peer ReviewedPostprint (published version
In this study, the influence of an electrochemical pre-treatment was evaluated in dyeing wastewater reuse for five reactive dyes for cotton fabrics. The most proper dyeing method was established and the influence of alkali was also studied. Wastewater was treated in an electrochemical cell at 20 Lh_1 and 40 mA/cm2 for between 3 and 15 minutes before being reused. During the electrochemical treatment the evolution of the dye degradation was evaluated by COD measurements. From the results, it can be concluded that 70% of the wastewater can be satisfactorily reused by direct bath reuse with most of the reactive dyes obtaining DE (CMC (2:1)) values below 1 with respect to the reference. Differences of DE (CMC (2:1) can be improved up to 75% by applying an electrochemical pre-treatment. In DE (CMC (2:1)) values, DL* was found to be the most influential parameter. Finally, the influence of the level of dye degradation in the wastewater was observed as non-relevant in the direct reuse of the bath for most of the studied dyesPostprint (published version
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