Decolorization Of Direct Dye Research Articles

Decolorization of direct dye in textile wastewater by ozonization in a semi-batch bubble column reactor

Decolorization of wastewater containing direct dye (Sirius Blue SBRR) by ozonization was studied in an attempt to abate pollution caused by textile dyeing houses and dye-producing plants. The decolorization process of the direct dye was carried out by bubbling ozone at the bottom of a bubble column reactor containing the dye solution. The effect of dye concentration, ozone dose, ozone-air flow rate and solution pH on the rate of decolorization was studied. The reaction rate was followed by measuring the dye concentration at different times of the decolorization process. The rate of dye oxidation was found to increase with increasing ozone concentration in the air-ozone and to decrease with increasing the dye concentration. The rate of dye oxidation increases with increasing the air–ozone flow rate and solution pH, reaches a maximum and then decreases with a further increase in the air–ozone flow rate. The results with the direct dyestuff wastewater showed that decolorization was remarkable under the basic condition of pH 12. A large amount of bubbles was formed at a high ozone–air flow rate. After 26 min of ozone treatment, decolorization was completed. From these results, the ozone treatment of the dyestuff wastewater in decolorization was excellent.

Decolorization of direct dyes with manganese peroxidase from white-rot basidiomycete Ganoderma lucidum IBL-05

Decolorization of direct dyes with manganese peroxidase from white-rot basidiomycete Ganoderma lucidum IBL-05

Decolorization of direct dyes by salt fractionated turnip proteins enhanced in the presence of hydrogen peroxide and redox mediators

The present paper demonstrates the effect of salt fractionated turnip ( Brassica rapa) proteins on the decolorization of direct dyes, used in textile industry, in the presence of various redox mediators. The rate and extent of decolorization of dyes was significantly enhanced by the presence of different types of redox mediators. Six out of 10 investigated compounds have shown their potential in enhancing the decolorization of direct dyes. The performance was evaluated at different concentrations of mediator and enzyme. The efficiency of each natural mediator depends on the type of dye treated. The decolorization of all tested direct dyes was maximum in the presence of 0.6 mM redox mediator at pH 5.5 and 30 °C. Complex mixtures of dyes were also maximally decolorized in the presence of 0.6 mM redox mediator (1-hydroxybenzotriazole/violuric acid). In order to examine the operational stability of the enzyme preparation, the enzyme was exploited for the decolorization of mixtures of dyes for different times in a stirred batch process. There was no further change in decolorization of an individual dye or their mixtures after 60 min; the enzyme caused more than 80% decolorization of all dyes in the presence of 1-hydroxybenzotriazole/violuric acid. However, there was no desirable increase in dye decolorization of the mixtures on overnight stay. Total organic carbon analysis of treated dyes or their mixtures showed that these results were quite comparable to the loss of color from solutions. However, the treatment of such polluted water in the presence of redox mediators caused the formation of insoluble precipitate, which could be removed by the process of centrifugation. The results suggested that catalyzed oxidative coupling reactions might be important for natural transformation pathways for dyes and indicate their potential use as an efficient means for removal of dyes color from waters and wastewaters.

Degradation and sludge production of textile dyes by Fenton and photo-Fenton processes

The degradation and decolorization of direct dye (Everdirect supra turquoise blue FBL), acidic dye (Isolan orange S-RL) and vat dye (Indanthrene red FBB) have been investigated by Fenton and UV/Fenton processes. The effects of solution pH, Fe 2+ dosages and H 2O 2 dosages have been studied by jar-test experiments. A comparative study for Fenton and UV/Fenton reactions by photoreactor has also been carried out by scale-up the optimum conditions, obtained through jar-test experiments. Fenton process is highly efficient for color removal for three dyes tested and for TOC removal of FBB and FBL. UV/Fenton showed slighter increase in treatment efficiency than that of Fenton process for both FBB and FBL dye solutions. S-RL improved much more TOC removal% by UV-irradiation. Sludge productions were compared for FeCl 3-, FeSO 4-coagulation and Fenton reaction in order to prove the dual role of FeSO 4 in Fenton process.