• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1262-1267
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• 2008

Reductive discolorization studies were conducted. Azo-dyes usually have biological toxicity and it is known that the dyes are hardly removed by biological treatments. One of the simplest way to remove the color is to break the azo-bond and it is possible to break the bond with zero-valent metals. Three types of azo-dyes (Cibacron Briliant Yellow 3G-P (CBY3G-P), Benzopurpurin 4b (B-4B), Chicago sky blue 6b (CSB6B)) were tested. All tested azo-dyes were highly pH dependent and lower pH was preferred. The reaction mechanism was reductive cleavage and amines were expected as products. The dissolved iron ions from zero-valent iron can also remove the color through coagulation and precipitation and a set of experiments were conducted to evaluate the contribution by the dissolved iron. The results indicated that the contribution were also dependent on the type of dyes. This study showed that the reductive cleavage using zero-valent iron could be an alternative for the azo-dye waste water.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.333-339
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• 2003

The cotton fabrics treated with 50% N-methylmorpholine-N-oxide(50% NMMO) and 75% N-methylmorpholine-N-oxide(75 % NMMO) aqueous solution were examined in terms of the dyeability comparing with those of regular cotton fabrics. The dyeing rate was increased with the increase of the concentration of NMMO in the treatment aqueous solution. The NMMO treatment increased the diffusion coefficients and decreased the activation energy of direct dye onto cotton fabrics. This means that the NMMO could change the micro-structure of cotton fabrics.