Electro-oxidacion de fenol en una columna de burbujeo de flujo paralelo descendente

Abstract

In the context of water remediation, advanced oxidation processes have been proven to be an effective solution. In most of the cases, however, the reaction systems are usually highly expensive, because of the addition of chemical substances or energy consumption. This usually constrains their application at an industrial scale. This has motivated several researchers to develop technologies able not only to intensify the processes but able also to increase the sustainability of the whole process. In this sense, this work aimed to assess a relatively novel technology, a Downflow Bubble Column Electrochemical Reactor (DBCER), in the mineralization of a rather typical organic pollutant, phenol. The studied variables were: current density (20-60 mA/cm2), electrolyte concentration (0-0.01 M), recirculation of the liquid phase (4.7 and 6 L/min) and pH (3 and 7). The response variables were total organic carbon (TOC), phenol and by-products concentration, oxidant species concentration (O2, H2O2 and O3). Some hydrodynamic parameters and volumetric mass transfer coefficient were also determined, such as the bubble diameter and volume fraction of gas. The highest mineralization degree was around 75 % under pH 3, 60 mA/cm2, 4.7 L/min and an electrolyte concentration of 0.05 M. Under these conditions, it was figured out that the phenol oxidation occurs mainly by ozone attack and the main remaining compound was oxalic acid. Although at pH 7 the mineralization degree was lower than at pH 3, it was demonstrated by a biotoxicity study on Cyprinus carpio that the original toxicity was significantly decreased. Thus, it was demonstrated that the DBCER can be applied at a pre-pilot scale, in the electro-oxidation process, in which in-situ generation of O2, H2O2 and O3. Because of the unique design of this reactor, the electrogenerated gases can be better utilized than in other reactors. An application to intellectually protect the developed technology was submitted to IMPI and the number of the application is Mx/a/2017/012722.