Tecnologias eletroquímica: caracterização de reator, degradação e detecção de norfloxacina

• Ano de defesa: 2024
• Autor(a) principal: Morais, Crislânia Carla de Oliveira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte; Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM QUÍMICA
• Palavras-chave em Português: Eletroquímica; Processos oxidativos avançados eletroquímico; Fluidodinâmica computacional; Índice de biodegradabilidade; Eletroanálise; Fármaco; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufrn.br/handle/123456789/62678

Water contamination has become an emerging priority in recent years, consequently, the development of methodologies aimed at treating and monitoring water and effluents has grown significantly, and electrochemical technology stands out both in the development of sensors and in the application of advanced oxidative processes. electrochemicals (POAEs). In this research, electrochemical methodologies were used both in the characterization of a flow reactor with Ti/TiO2RuO2IrO2 plates (anode) and Ti (cathode), and for the degradation and detection of norfloxacin (NOR). The diffusion limit current technique was used to determine the experimental mass transfer coefficients (km) and the dimensionless numbers at different flow rates (25, 75, 250 and 500 L h ̶ 1). Computational fluid dynamics (CFD) was used to evaluate the flow velocity distribution within the reactor. The km values and CFD simulation showed a system totally dependent on flow, the correlation of dimensionless numbers indicated a predominance of turbulent regime. 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 of NOR, at different current densities (j). The degradation process was monitored by UV-visible spectroscopy, with decreases of 70%, 92% and 85% in the initial concentration of the drug, and in total organic carbon with mineralization of 28%, 42% and 36%, for the j of 20, 40 and 60 mA cm ̶ 2 , respectively. Ion chromatography indicated the formation of short-chain organic acids (formic and acetic) at the end of electrolysis. The biodegradability index (BOD5/COD ≥ 0.5) showed that after the electrochemical treatment the substrate was converted into a more biodegradable material. An amperometric sensor was developed, using a carbon fiber rod (FC) to monitor online the degradation process of the NOR molecule via POAEs. The electroactivity study of NOR on FC using Britton Robson buffer at pH 2.0 showed an irreversible oxidation peak at 1.13 V vs. Ag/AgCl(sat). The study of pH (2.0 – 9.0) indicated that the determining step of the reaction involved 1 proton and 1 electron in an EC mechanism; potential sweep velocity study indicated a mixed adsorption-diffusion process. In the amperometric analysis, the potential was set at 1.2 V. 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 and quantification limits of 0.5 and 1.8 µmol L ̶ 1, respectively. Reproducibility and repeatability presented a relative standard deviation of 2.1% and 2.9%, respectively. The applicability of the proposed sensor was compared with the spectrophotometric method by monitoring the NOR degradation process by POAEs, and the results obtained were in agreement. In this way, electrochemical methodologies can be effectively applied from different perspectives, both in monitoring and mitigating environmental pollutants.