Gallic acid photochemical oxidation as a model compound of winery wastewaters

Abstract

Winery wastewaters (WW) are characterized by their high organic load and by the presence of non-biodegradable compounds such as phenolic compounds. This study was undertaken to evaluate the capacity of different Advanced Oxidation Processes (AOP) combined with several radiation sources to degrade the phenolic compound Gallic Acid (GA). A toxicological assessment was also carried out to evaluate the subproduct's harmful effect generated during the most efficient AOP in the GA photoxidation. Through the course of the study it was verified that the UV radiation lamp TNN 15/32 showed the capacity to degrade 34.7% of GA, the UV radiation lamp TQ 150 achieved a value of 20.2% and the solar radiation presented only a value of 2.3% in 60 minutes. The combination of different advanced oxidation processes (Fenton's reagent, ferrioxalate and heterogeneous photocatalysis) were evaluated with the previously studied sources of radiation. From the experiments conducted it was possible to suggest that the AOP in combination with Fe^{2 +} + H₂O₂ + UV TNN 15/32 (photo-Fenton process) was the most efficient process thereby achieving the GA degradation value of 95.6% in 7.5 minutes and resulting in a total elimination of toxicity.

Keywords:

• Winery wastewater
• gallic acid
• advanced oxidation processes
• toxicity assessment

Acknowledgments

Marco S. Lucas thanks FCT (Fundação para a Ciência e Tecnologia – Portugal) for the PhD grant (BDE/15576/2005).