UV/TiO2 Photocatalytic Degradation of Xanthene Dyes

Authors

  • Luciana Pereira,

    Corresponding author
    • IBB-Institute of Biotechnology and Bioengineering, Centre of Biologic Engineering, Minho University, Braga, Portugal
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  • Raquel Pereira,

    1. IBB-Institute of Biotechnology and Bioengineering, Centre of Biologic Engineering, Minho University, Braga, Portugal
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  • Catarina S. Oliveira,

    1. IBB-Institute of Biotechnology and Bioengineering, Centre of Biologic Engineering, Minho University, Braga, Portugal
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  • Laura Apostol,

    1. Department of Environmental Engineering and Management, Faculty of Chemical Engineering & Environmental Protection, Gheorghe Asachi” Technical University of Iasi, Iasi, Romania
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  • Mariana Gavrilescu,

    1. Department of Environmental Engineering and Management, Faculty of Chemical Engineering & Environmental Protection, Gheorghe Asachi” Technical University of Iasi, Iasi, Romania
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  • Marie-Noëlle Pons,

    1. Laboratoire Réactions et Génie des Procédés (UPR 3349 CNRS), Nancy University, INPL, Nancy Cedex, France
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  • Orfan Zahraa,

    1. Laboratoire Réactions et Génie des Procédés (UPR 3349 CNRS), Nancy University, INPL, Nancy Cedex, France
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  • Maria Madalena Alves

    1. IBB-Institute of Biotechnology and Bioengineering, Centre of Biologic Engineering, Minho University, Braga, Portugal
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Corresponding author email: lucianapereira@deb.uminho.pt

Abstract

UV/titanium dioxide (TiO2) degradation of two xanthene dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a photocatalytic reactor. Photocatalysis was able to degrade 98% of Ery and 73% of Eos and led to 65% of chemical oxygen demand removal. Experiments in buffered solutions at different initial pH values reveal the pH dependence of the process, with better results obtained under acidic conditions due to the electrostatic attraction caused by the opposite charges of TiO2 (positive) and of anionic dyes (negative). Batch activity tests under methanogenic conditions showed the high toxicity exerted by the dyes even at low concentrations (~85% with initial concentration of 0.3 mmol L−1), but the end products of photocatalytic treatment were much less toxic toward methanogenic bacteria, as detoxification of 85 ± 5% for Eos and 64 ± 7% for Ery were obtained. In contrast, the dyes had no inhibitory effect on the biogenic-carbon biodegradation activity of aerobic biomass, obtained by respirometry. The results demonstrate that photocatalysis combining UV/TiO2 as a pretreatment followed by an anaerobic biological process may be promising for the treatment of wastewaters produced by many industries.

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