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Wang, C.* ; Yediler, A. ; Lienert, D. ; Wang, Z.* ; Kettrup, A.

Ozonation of an azo dye C.I. Remazol Black 5 and toxicological assessment of its oxidation products.

Chemosphere 52, 1225-1232 (2003)
DOI
Open Access Green as soon as Postprint is submitted to ZB.
The effect of ozonation (20.5 mg l−1) on the degradation processes of an azo dye, Remazol Black 5 (RB5; CI) was studied. Conventional parameters such as chemical oxygen demand (COD), total organic carbon (TOC), pH, conductivity, colour removal, biodegradability (BOD5/28), and toxic potential of the dye and its degradation products were monitored during the process. The results obtained indicated that ozonation is a highly effective way to remove the colour of a corresponding dye solution. However, a considerable organic load still remained as indicated by high COD and TOC residues. The COD, TOC reductions were about 40% and 25% for 6 h ozonation of 2 g l−1 RB5 aqueous solution. During the ozonation process the rapid decrease of pH and the sharp increase of conductivity indicated the formation of acidic by-products and small fragments and ions which were identified by high performance ion chromatography. The BOD28 data revealed that first by-products after partial ozonation (10–150 min) of RB5 were more biodegradable than the parent compound and ozonation can enhance the biodegradability of azo dyes. During the first 150 min of total 360 min of oxidation, the formation of first by-products with high toxic potential took place as it could be confirmed by two acute toxicity-screening tests, the bioluminescence test (Vibrio fischerii) and the neutral red cytotoxicity assay (rat hepatoma cells). The significant enhancement of microbial biodegradability after long-term ozonation could also be seen as a decrease of toxic intermediates in correlation with the ozonation time as indicated in BOD28 biological degradation test results.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Reactive dyes; Ozonation; Acute toxicity; Biodegradability; BOD5/28; Oxidation by-products; Bioluminescence test; The neutral red cytotoxicity assay
ISSN (print) / ISBN 0045-6535
e-ISSN 1879-1298
Journal Chemosphere
Quellenangaben Volume: 52, Issue: 7, Pages: 1225-1232 Article Number: , Supplement: ,
Publisher Elsevier
Publishing Place Kidlington, Oxford
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Ecological Chemistry (IOEC)