Banca de DEFESA: FLORYMAR ESCALONA DURAN

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FLORYMAR ESCALONA DURAN
DATE: 27/08/2021
TIME: 11:00
LOCAL: VIDEO CONFERENCIA
TITLE:

Treatment of residual gaseous emissions by electro-absorbent technologies.

KEY WORDS:

Volatile organic compounds, polluted air stream, absorbers, electrochemical processes, BDD anode, electro-scrubbing, mediated electrochemical oxidation, jet mixer, packed column, VOCs removal.

PAGES: 321
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

In the search for new alternatives for the treatment of volatile organic compounds (VOCs) and gases with an unpleasant odor, in this work, the degradation of gaseous pollutants using electrochemically assisted absorbent devices was studied. For this, a packed column or a Venturi injector was integrated into an electrochemical cell (with boron-doped diamond anodes (BDD) supported on Tantalum and/or Silicon substrates) and the efficiency in the removal of toluene and perchloroethylene (PCE) from air streams was studied, without and with the mediating effect of the Co(II)/Co(III) couple in solution. In the first results, it was obtained that the formation of Co(III) on the Ta/BDD anode was significantly higher concerning the Si/BDD anode, which was later corroborated with the treatment of gaseous streams contaminated with PCE, where again the Ta/BDD anode was more efficient both in the production of Co(III) species and in the degradation of the pollutant, and the degradation rate increased in the presence of cobalt, especially when previous electrolysis was carried out for the accumulation of oxidants. Comparing the absorbent devices, it was obtained that the removal of PCE was more efficient using the Venturi injector both in absorption experiments and in electroabsorption. For its part, the removal of toluene by mediated electroabsorption yielded the best efficiencies, especially at high current densities; however, important participation of the sulfate/persulfate pair was also suggested in electroabsorption experiments with only an acidic medium as a supporting electrolyte. With the packed column, the system showed a better performance for the electrochemical degradation of toluene, while the Venturi injector reported the best efficiencies for the retention of the contaminant in the electrolyte/absorbent. The results obtained are interesting because, in general, both electroabsorption systems allowed the efficient removal of the treated pollutants. The BDD anode substrate seems to have a determining effect on the efficiency of the mediated electrochemical treatments, an aspect that has been little investigated and therefore offers a new line of study. Finally, the mediating effect of the Co(II)/Co(III) pair was significant in the treatment of PCE with pre-electrolysis and in the oxidation of toluene at the highest current density, in both cases using Si/BDD anodes, which highlights the relevance of mediated electro-oxidation mechanisms. The results obtained with the highest amounts of Co(III) generated at the Ta/BDD anode propose that the promotion of oxidants is not always positive from the point of view of their accumulation in the electrolyte, Ta/BDD anode appears to promote sufficient amounts of hydroxyl radicals, making the presence of the metal unnecessary.

The high potential demonstrated so far by this integrated technology and the need to develop new gas treatment processes for real applications, suggest that electro-scrubbing technology may, in the long term, have important industrial applications in the treatment of numerous pollutants. gaseous.

BANKING MEMBERS:
Externa à Instituição - ENGRACIA FERNÁNDEZ JIMÉNEZ - UC
Presidente - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externa à Instituição - DANYELLE MEDEIROS DE ARAUJO - UERN
Externa ao Programa - 2275848 - ELISAMA VIEIRA DOS SANTOS
Externo à Instituição - MANUEL ANDRES RODRIGO RODRIGO - UC