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Ozonation of the Purified Hydrolyzed Azo Dye Reactive Red 120 (CI).
J. Environ. Sci. Health A Tox. Hazard. Subst. Environ. Eng. A37, 707-713 (2002)
The combination of chemical and biological water treatment processes is a promising technique to reduce recalcitrant wastewater loads. The key to the efficiency of such a system is a better understanding of the mechanisms involved during the degradation processes. Ozonation has been applied to many fields in water and wastewater treatment. Especially for effluents of textile finishing industry ozonation can achieve high color removal, enhance biodegradability, destroy phenols and reduce the COD. However, little is known about the reaction intermediates and products formed during ozonation. This work focuses on the oxidative degradation of purified (>90%), hydrolyzed Reactive Red 120 (Color Index), a widely used azo dye in the textile finishing processes with two monochlorotriazine anchor groups. Ozonation of the dye in ultra pure water was performed in a laboratory scale cylindrical batch reactor. Decolorization, determined by measuring the light absorbance at the maximum wavelength in the visible range (53 5 nm), was almost complete after 150 min with an ozone concentration of 12.8 mg/l. The TOC/TOC0 ratio was about 74% and the COD was diminished to 46% of the initial value. The BOD5/COD ratio increased from 0.01 to 0.14. To obtain detailed information on the reaction processes during ozonation and the resulting oxidation products organic and inorganic anions were analyzed. Oxidation and cleavage of the azo group yielded nitrate. Cleavage of the sulfonic acid groups of aromatic rings caused an increase in the amount of sulfate. Formic acid and oxalic acid were identified as main oxidation products by high performance ion chromatography (HPIC). The concentrations of these major products were monitored at defined time intervals during ozonation.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Ozonation; Reactive Red 120; Azo dye; Textile finishing industry
ISSN (print) / ISBN
1093-4529
e-ISSN
1532-4117
Quellenangaben
Volume: A37,
Pages: 707-713
Publisher
Taylor & Francis
Non-patent literature
Publications
Reviewing status
Peer reviewed
Institute(s)
Institute of Ecological Chemistry (IOEC)