Degradation mechanism of azo dye C. I. reactive red 2 by iron powder reduction and photooxidation in aqueous solutions

Wu, Feng; Deng, Nansheng; Hao, Hua

doi:10.1016/s0045-6535(99)00538-x

Cited by 257 publications

(110 citation statements)

References 9 publications

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“…Beydilli et al [8] analyzed the degradation products of RR2 by HPLC and UV-Vis spectra and observed the presence of aniline and aminohydroxynaphthalene derivatives in the effluent. Further, Feng et al [21] also have reported the formation of degradation products of RR2 and the shift of the peaks to a new wavelength with a value of 245 nm in the effluent spectra. Although they used iron powder as a reducing agent their effluent (liquid after iron powder treatment) absorbance spectra was found to be similar to the spectra of the effluent from R2 and R3.…”

Section: Colour Removalmentioning

confidence: 95%

Adsorption and biological decolourization of azo dye Reactive Red 2 in semicontinuous anaerobic reactors

Maas

Chaudhari

2005

Process Biochemistry

174

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The microbial decolourization of Reactive Red 2 (RR2) dye has been studied under anaerobic conditions. Three semicontinuous bioreactors were operated with dye concentrations-R1 (control: 0 mg RR2 l −1 ), R2 (100 mg RR2 l −1 ) and R3 (200 mg RR2 l −1 ). The parameters monitored were, oxidation-reduction potential (ORP), methane production, colour and chemical oxygen demand (COD) removal during the feeding cycles. The oxidation-reduction potential values for the first few days were above −150 mV, which later on decreased to less than −275 mV in all the reactors. Colour removal during the first few days of operation was due to adsorption of dye on to anaerobic biomass. However, under steady state conditions, colour removal was above 76% for both the dye containing reactors and it was due to biologically mediated degradation. Methane production and chemical oxygen demand removal in the control and dye containing reactors were almost the same. Integrated analysis of the monitored parameters indicated that, the primary mechanism of colour removal was adsorption of RR2 on to anaerobic biomass and subsequent degradation. Decolourization rates were found to be first order with respect to dye concentration, although an increase in the influent dye concentration resulted in a decrease in the rate from 0.0074 (g volatile suspended solid, VSS) −1 h −1 (100 mg RR2 l −1 ) to 0.0039 (g VSS) −1 h −1 (200 mg RR2 l −1 ). Based on total methane production no inhibition effect of dyes was observed but total methanogenic activity (TMA) results exhibited inhibition of methanogenesis.

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Section: Colour Removalmentioning

confidence: 95%

Adsorption and biological decolourization of azo dye Reactive Red 2 in semicontinuous anaerobic reactors

Maas

Chaudhari

2005

Process Biochemistry

174

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“…However, this is not applicable to direct dyes (DB71) that usually exhibit high levels of colour removal independent of the number of sulfonate groups in the dye structure, reinforcing the idea that steric hindrance and the number of azo bonds are responsible for the different decolourization times [14]. It has also been reported that a correlation between the enzyme redox potential and its activity towards the substrates could influence the decolourization rate [41,51]. In this context, the decolourization times obtained in the present work were in agreement with those of Kimura et al [52], who found a linear relationship between the cathodic peak potentials and the time of maximum decolourization for several azo dyes using an ascomycete yeast Issatchenkia occidentalis.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Aeromonas Spp. In Microbial Degradation and Decolorization of Reactive Black in Microaerophilic – Aerobic Condition

Shah¹

2014

J Bioremed Biodeg

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Azo dyes are a widespread class of poorly biodegradable industrial pollutants. In anaerobic environments, azo bonds are reductively cleaved yielding carcinogenic aromatic amines, many of which are assumed to resist further metabolism by anaerobes bacteria. The latter compounds generally require aerobic conditions for their degradation. Reactive Black was found to be degraded using Aeromonas spp. to α-ketoglutaric acid with transient accumulation of 4-aminobenzenesulphonic acid (sulphanilic acid), 4-amino, 3-hydronapthalenesulphonic acid and 4-amino, 5-hydronapthalene 2,7 disulphonic acid as a degradation intermediate in anaerobic facultative batch culture. Colour and Total Organic Carbon (TOC) was successfully removed more than 95% and up to 50% respectively. There is no significant correlation between pH and oxygen depletion since there is slightly change in pH was observed (pH from 7.21 to 7.25) though the anaerobiosis was found developed throughout the experiment (redox potential from 0.7 to 1.6 mV). The anaerobic metabolism of glucose as co-metabolite also shown to provide the electrons required for the initial reductive cleavage of the azo group. This finding suggest that it is possible to mineralize the azo dye in the environment; thereby, avoiding accumulation of toxic intermediates in the water. The results provide evidence that the successive microaerophilic/aerobic stages, using Aeromonas spp. in the same bioreactor, were able to form aromatic amines by the reductive break down of the azo bond and to oxidize them into non-toxic metabolites. Journal of Bior emediation & Biodegradation

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“…The chromophore containing the azo bond has absorption in the visible region, while benzene and naphthalene rings in the UV region. Moreover, the naphthalene ring absorption wavelength is higher than that of benzene rings 32 . The spectrum of the initial solution presents the characteristics of the azo bond which causes the colour at 535 nm and the benzene and naphthalene rings bonded to the azo bond at 220 and 322 nm, respectively.…”

Section: Uv-vis Spectra Analysismentioning

confidence: 90%

Decolourization of an azo dye in aqueous solution by ozonation in a semi-batch bubble column reactor

Abidin

Fahmi²,

Ong³

et al. 2015

ScienceAsia

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ABSTRACT:The oxidative degradation of the azo dye Reactive Red 120 by ozonation was investigated. The decolourization was carried out by bubbling ozone at the bottom of a bubble column reactor containing the dye solution. The colour, chemical oxygen demand, and total organic carbon removal were evaluated, and the contaminants were characterized based on the changes in UV-Vis and FT-IR spectra. It was observed that changes of UV-Vis spectra represent the disappearance of both azo and aromatic groups, which causes the colour removal. FT-IR analysis indicated that ozonation shifts the functional groups in the azo dye which results in decolourization, a decrease in aromaticity, and an increase in acidity. The results indicate that the chromophore is destroyed and partially mineralized to small fragments during ozonation. The alkaline pH was favourable to decomposition by ozonation, initiated by the formation of the hydroxyl radicals. The oxidation followed first-order kinetics and the completed decolourization confirmed the capability of ozonation to cleave the azo bond from the dye.

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Degradation mechanism of azo dye C. I. reactive red 2 by iron powder reduction and photooxidation in aqueous solutions

Cited by 257 publications

References 9 publications

Adsorption and biological decolourization of azo dye Reactive Red 2 in semicontinuous anaerobic reactors

Adsorption and biological decolourization of azo dye Reactive Red 2 in semicontinuous anaerobic reactors

Evaluation of Aeromonas Spp. In Microbial Degradation and Decolorization of Reactive Black in Microaerophilic – Aerobic Condition

Decolourization of an azo dye in aqueous solution by ozonation in a semi-batch bubble column reactor

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