Banca de DEFESA: GRAZIELE DE ARAUJO CARVALHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : GRAZIELE DE ARAUJO CARVALHO
DATE: 28/07/2023
TIME: 14:00
LOCAL: Instituto de Química
TITLE:

Photodegradation Study of Pesticides of Different Chemical Classes and the Influence of Physical-chemical Parameters

KEY WORDS:

pesticidas em água,  piretróides, organofosforados, estrobilurinas, fotodegradação, DLLME, CG-MS

 

pesticides in waters, piretroids, organophosphorous pesticides, estrobilurines, DLLME, GC-MS

PAGES: 120
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Análise de Traços e Química Ambiental
SUMMARY:

The characteristics of water are significantly altered by pollution. Contaminants, such as pesticides, impact surface and groundwaters, compromising their quality and causing adverse effects on the health of populations. Pesticides are pollutants that can be present in water and are derived from agricultural activities. Once in the aquatic environment, pesticides can undergo a series of interactions and their persistence will depend on their transformation kinetics, which, in turn, depends on their physicochemical characteristics and environmental factors. This work aimed to study the photodegradation process, in aqueous medium, of three pesticides, belonging to different chemical classes, namely: fenthion, bifenthrin and azoxystrobin. The influence of the initial concentration and the physicochemical parameters pH, radiation power and the addition of metals was evaluated. In order to analyze the solutions, a method was developed, validated and applied, and was based on Dispersive Liquid Microextraction (DLLME) and analysis by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The extraction optimization was performed by the Fractional Factorial design, involving the factors type and volume of the extracting solvent, type and volume of the dispersing solvent, pH, salting out effect and centrifugation time. The evaluation of the variables that significantly influenced the extraction process was made by the Doehlert Matrix planning and the adjusted values were: chloroform as extractor (400 μL); methanol as disperser (240 μL); pH = 7.0; addition of 0.8g of salt and centrifugation for 2 minutes at 3000 rpm. The optimized method showed a good performance in the parameters selectivity, limits of detection and quantification, linearity, precision and accuracy. The degradation study showed that, among the pesticides studied, fenthion was the pesticide which showed the most effective degradation in the experiments performed. The degradation was directly affected by the concentration of pesticides, the power of the incident radiation, the addition of metals and the quality of the water used in the solutions, while the pH did not significantly influence the degradation rates. The toxicity of pesticides and their dynamics in the environment make it necessary to monitor the presence of these compounds in water, to control their potability and quality for consumption.

COMMITTEE MEMBERS:
Presidente - 1143276 - PEDRO AFONSO DE PAULA PEREIRA
Interna - 1303987 - MARIA ELISABETE MACHADO
Interna - 1553299 - GISELE OLIMPIO DA ROCHA
Interna - 1299469 - LUCIANA ALMEIDA DA SILVA
Externa à Instituição - SABRINA TEIXEIRA MARTINEZ - UFRJ
Externo à Instituição - JEANCARLO PEREIRA DOS ANJOS - UFABC
Externo à Instituição - RICARDO LEAL CUNHA
Externo à Instituição - FREDERICO DE MEDEIROS RODRIGUES