Banca de DEFESA: CRISLÂNIA CARLA OLIVEIRA MORAIS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : CRISLÂNIA CARLA OLIVEIRA MORAIS
DATE: 31/01/2024
TIME: 14:00
LOCAL: videoconferência
TITLE:

Electrochemical technologies: Characterization of a flow recirculation reactor, degradation and detection of Norfloxacin.

KEY WORDS:

Electroanalysis; CFD Simulations, EAOP; DSA; Biodegradability Index

PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

Water contamination and pollution are priority and emerging issues, both from a scientific and technological point of view. The need to develop efficient methodologies for treating and monitoring water and effluents has grown significantly. In this context, electrochemical technology (ET) has stood out both in the development of sensors and in the application of electrochemical advanced oxidative processes (EAOP). In this work, ET was used to characterize a flow recirculation reactor with parallel rectangular plates of Ti/TiO2RuO2IrO2 (anode) and Ti (cathode), and for the degradation and detection of the drug Norfloxacin (NOR). The diffusion limit current technique was used to determine the experimental mass transfer coefficient (km) and the dimensionless numbers at different flow rates (25, 75, 250 and 500 L h 1), and computational fluid dynamics (CFD) to evaluate the flow velocity distribution within the reactor. The km values and the CFD simulation showed a system totally dependent on the flow rate and the correlation of the dimensionless numbers indicated the predominance of a turbulent regime, at any flow rate. The optimal condition for using the proposed reactor was at a flow rate of 500 L h 1 (km = 1.9 × 10 4 m s 1) and its efficiency was confirmed by electrochemical oxidation studies of 2.5 × 10−4 mol L−1  NOR, at different current densities (j). The degradation process was monitored by UV-visible spectroscopy and total organic carbon (TOC). Molecular absorption spectrophotometry showed a decrease of 70%, 92% and 85% of the initial drug concentration, and TOC analysis showed a mineralization of 28%, 42% and 36% for 20, 40 and 60 mA cm  2, respectively. The drug degradation process was confirmed by ion chromatography (IC), which indicated the formation of short-chain organic acids (formic and acetic acids) at the end of electrolysis. The biodegradability index was also investigated and the results (BOD5/COD ≥ 0.5) showed that after electrochemical treatment the substrate was transformed into a more biodegradable material, which favors the mitigation of environmental impacts. Sequentially, an amperometric sensor with a simple approach was developed, using a carbon fiber (CF) rod as a transducer to monitor online the degradation process of the NOR molecule via EAOP. The electroactivity study of NOR on CF using Britton-Robinson buffer at pH 2.0 showed an irreversible oxidation peak at 1.13 V vs. Ag/AgCl. By correlating Ep versus pH, it was possible to indicate the pKa values of the drug (6.5 and 8.1); the pH study indicated that the determining step of the reaction involved 1 proton and 1 electron in an EC mechanism; and the potential scan rate study showed a mixed adsorption-diffusion process. For the amperometric analysis, the potential was set at 1.2 V, which presented the highest current value. The calibration curve presented a linear range between 1.6 µmol L 1 and 30.0 µmol L 1, with R2 = 0.998, and detection (DL) and quantification (QL) limits of 0.01 µmol L 1 and 0.4 µmol L 1, respectively. The reproducibility and repeatability presented a DPR of 2.1% and 2.9%, respectively, indicating the accuracy of the chronoamperometric sensor. The applicability of the proposed sensor was compared to that of the spectrophotometric method by monitoring the NOR degradation process by EAOP and the results obtained were in agreement. In this way, electrochemical technology can be effectively applied from different perspectives, both in monitoring and mitigating environmental pollutants.

COMMITTEE MEMBERS:
Presidente - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Interna - 2413537 - POLLYANA SOUZA CASTRO
Externa ao Programa - 2275848 - ELISAMA VIEIRA DOS SANTOS - UFRNExterno à Instituição - DANYELLE MEDEIROS DE ARAUJO - UNESP
Externa à Instituição - SUELY SOUZA LEAL DE CASTRO - UERN
Externo à Instituição - THIAGO MIELLE BRITO FERREIRA OLIVEIRA - UFCA