&lt;b&gt;Influence of pH and concentration on the decolorization and degradation of BR red azo dye by ozonization

Jéssica Luiza Bueno Trevizani,Fernando Hermes Passig,Gilson Júnior Schiavon,Adriana Neres De Lima Model,Karina Querne De Carvalho,André Nagalli

doi:10.4025/actascitechnol.v40i1.35436

Abstract

Ozone application has been generally reported based only on the oxidation of textile dyes. In this study, a central composite design and surface response methodology were applied to optimize operational parameters pH and concentration of the dye in the decolorization process. The oxidation of Corafix BR Red Azo dye in aqueous solutions was carried out in a semi-batch bubble column reactor with ozone production at 0.702 g hour -1 . Tests were performed at pH 4, 7 e 10 and initial dye concentration of 50, 100 and 150 mg L -1 . The maximum removal efficiency was 98% for pH 10 and initial dye concentration of 50 mg L -1 with pseudo-first order constant rate (k 1 ) of 0.0595 min -1 . Statistical analysis determined the influence of pH and dye concentration in the decolorization process. The pH presented a positive effect on the decolorization while the variation in dye concentration had a negative effect on the same variable, indicating the higher the pH and the lower the initial concentration of dye, the higher the efficiency. Toxicity tests performed before and after ozonization showed acute toxicity for the test organism Daphnia similis with higher percentage of mortality after ozonization.

Highlights

Agricultural and industrial sectors are the main water consumers in the world, with the textile sector presenting higher volume ratio of water consumed by processed textile material
The increase in ozone production was from 0.402 to 0.702 g hour-1 over the increase of air flowrate from 5 to 15 L min-1, being this maximum value adopted in this study
These findings are in accordance with the literature (Tabrizi et al, 2011; Gao et al, 2012; Sharma et al, 2013) confirming that ozonation is a very efficient process for color removal and the time required for the complete decolorization gradually increase with increase in the initial concentration

Summary

Introduction

Agricultural and industrial sectors are the main water consumers in the world, with the textile sector presenting higher volume ratio of water consumed by processed textile material. An ozonation system consisting of air compressor, ozone generator, gas flow meter and bubble column reactor was operated to evaluate the behavior of removing color from an aqueous solution containing the reactive Corafix BR Red azo dye.

Results

Conclusion