Aplicação e simulação de reator eletroquímico em série na conversão do alaranjado de metila em ácidos orgânicos e hidrogênio

Abstract

The present work aimed to apply an electrochemical technology, in order to, evaluate and analyze the efficiency on the degradation from model organic compound toward to carboxylic acids, as well as the simultaneous production of H2(g) in different electric current densities (15, 30 and 45 mAcm- ²) and for three different configurations on the electrochemical reactor. In first step, a three-compartment flow reactor in series mode was designed and fabricated, combining the electrocatalytic properties of two non-active anodes (PbO2-F and BDD) and a stainless-steel mesh cathode separated by two Nafion 350® membranes. Moreover, a mathematical model was developed to represent the reactor, as well as the reactions involved in the electrochemical process. At first, the synthesis of the PbO2-F anode and its characterization by SEM-FEG and EDS were performed. Soon after, the assessment of the BDD and PbO2-F anodes by Linear Scanning Voltammetry was carried out to analyze their oxygen evolution potentials. The degradation process of the methyl orange dye was monitored by absorption spectroscopy in the UV-vis region, Electroanalysis and FTIR. Meanwhile, the quantification of carboxylic acids production, Ion Chromatography was performed. The adopted process presented excellent results for the degradation of the organic compound, reaching 100% color removal after 60 minutes of electrolysis for all conditions studied. The FTIR data showed that there was degradation of the dye, mainly because we did not observe the peak presence corresponding to the binding of azo group at 1422 cm -1 Under the same conditions for degradation, a simultaneous green H2 production of approximately 0.8 L was achieved by applying a current density of 45 mAcm-2 . The carboxylic acids production was monitored over time for the different conditions tested, and it was observed that there was a selective production of malonic acid, the which opens up the possibility of future studies for the application of electro-refinery concept using these residues. The model showed good adherence to the experimental data, confirming that it can describe and predicting production under different operating conditions.