**Acknowledgements**

The author knowledge the National Council for Scientific and Technological Development (CNPq) and the Sao Paulo Research Foundation (Fapesp).

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**Author details**

Nilce Ortiz

provided the original work is properly cited.

*Green Water Treatment for Pharmaceutical Pollution DOI: http://dx.doi.org/10.5772/intechopen.85116*

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Institute for Nuclear and Energy Research–IPEN, São Paulo, Brazil

\*Address all correspondence to: nortizbr@gmail.com

*Green Water Treatment for Pharmaceutical Pollution DOI: http://dx.doi.org/10.5772/intechopen.85116*

*Green Chemistry Applications*

wastewater with a complex dye mixture.

**Acknowledgements**

toward the hydroxyl radicals generated by AOPs; the natural organic matter (NOM) presence showed a synergistic effect increasing the E2 degradation, such degradation produces other radicals. The application of the visible light photodecomposition in a dye mixture of methylene blue (MB), methyl orange (MO), and rhodamine (RH) indicates the MO as the more stable azo compound than the other organic pollutants due to the aromatic groups attached at the end of the azo bond. Despite this fact when the light-driven photodecomposition uses the Ag2O as a catalyzer, it was the fastest and easiest decomposed compound. Published results indicate the visible light photodecomposition with Ag2O with the elimination of 90.2% of MO, 96.5% of RH, and 99.5% of MB using 4, 50, and 20 min, respectively. The photodecomposition acceleration synergistic effect is positively proportional to the azo dye concentration and no longer changes after reaching a specific equilibrium value. The comparison with the k values indicates higher rates for EBT > OG > MO > MR; the sequence is in agreement with the polarity of the four azo dye compounds. The azo compounds in the experiments were acid orange 7 (AO7), Congo red (CR), and amido black 10B (AB10B). The results were the same obtained for the other azo compounds confirming the synergistic oxidation effect. The possible decomposition mechanism includes the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) as a type of molecular frontier orbitals. The description of the acceleration of the photodegradation process with azo dyes' presence in a mixed dye solution is a synergy between the azo structure and Ag2O with the generation of aniline, sulfanilic acid, and phenol compounds which also accelerates the degradation of the non-azo compounds. The synergetic effect is beneficial for the Ag2O photodecomposition applicability to treat the ordinary real

The author knowledge the National Council for Scientific and Technological

Development (CNPq) and the Sao Paulo Research Foundation (Fapesp).

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