Banca de QUALIFICAÇÃO: JOSÉ EUDES LIMA SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ EUDES LIMA SANTOS
DATE: 24/08/2020
TIME: 09:00
LOCAL: Remotamente pelo google meet
TITLE:

 Produção catódica de hidrogênio por oxidação eletroquímica simultânea de soluções aquosas de vermelho de metila e 2,4-DNa usando ânodos de Pb/PbO₂, Ti/SnO₂ dopado com Sb e Si/BDD em uma célula eletrolítica de membrana de troca de prótons

KEY WORDS:

  Methyl Red, 2,4DNa, BDD anode, PbO₂ anode, Sb doped SnO₂ anode, Electroxidation, Hydrogen production, Oxygen production.

PAGES: 111
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

Due to environmental pollution problems, especially water, and the energy crisis caused by the growing use of fossil fuels that are not renewable and the products of their combustion are polluting, this work proposed producing hydrogen as an alternative means of production, since it is a renewable and clean energy source, by simultaneous oxidation of two of the most polluting sources of water, dyes and herbicides. For this purpose, the electrochemical oxidation of methyl red dye (MR) and the herbicide 2,4-dichlorophenoxyacetate (2,4DNa) was investigated in the anodes of Si/BDD, Pb/PbO₂ and Ti/SnO₂ doped with Sb in acidic aqueous medium by applying 30 mA cm^-2 with simultaneous production and quantification of the hydrogen gas produced in the cathode bay. The electrochemical experiments were performed in an electrochemical cell of two H-type compartments separated by a 417-type Nafion® membrane. The electrochemical degradation process was monitored by UV-vis, HPLC and Total Organic Carbon spectroscopy. The electrocatalytic properties of anodes and cathodes were evaluated by Tafel parameters. The results clearly showed that MR and 2.4DNa can be oxidized over such anodes, but both the oxidation level and anodic current efficiency varied significantly between them. The removal of MR color at the BDD anode was achieved in less than 20 min and only at this anode was the dye oxidized to carboxylic acids. For the Pb/PbO₂ and Ti/Sb-SnO₂ anode a longer time (120 min) of electrolysis was required to completely remove the color from the solution. A similar trend was observed in the electrochemical removal of 2.4DNa herbicide. The higher capacity of electrochemical removal of organic pollutants in the Si/BDD anode was attributed to the high participation of hydroxyl and sulfate radicals. The other anodes are not capable of producing sulfate radicals and have a lower electrocatalytic activity for the degradation of organic pollutants. Regarding hydrogen production, the results showed that the production speed of H₂ is dependent only on the applied current and the electrolysis time. In addition, the cathode current efficiency was over 80%. The use of other cathodic materials has similar efficiencies to platinum only differing in their chemical/electrochemical stability in the electrolytic medium studied. The production of oxygen in the anodic compartment was inhibited by about 50%, only in the Si/BDD anode, because of the formation of sulphate radicals that interfere in the reaction step of oxygen evolution by consuming hydroxyl radicals. Therefore, with this coupled system it is possible to reduce the impact of water pollution and generate a clean energy source that can be used to reduce the cost of electrochemical water treatment processes.

BANKING MEMBERS:
Presidente - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externa à Instituição - DAYANNE CHIANCA DE MOURA - UFRN
Interno - 348475 - DJALMA RIBEIRO DA SILVA
Externa ao Programa - 1412709 - NEDJA SUELY FERNANDES
Interna - 2413537 - POLLYANA SOUZA CASTRO