Banca de QUALIFICAÇÃO: LUANA RABELO HOLLANDA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUANA RABELO HOLLANDA
DATA : 27/04/2018
HORA: 08:00
LOCAL: SALA DO NUPEG
TÍTULO:

"REDUCTIVE DEGRADATION OF THE PESTICIDE ATRAZINE USING ZERO-VALENT COPPER, AND ITS POTENTIAL APPLICATION AS A PRE-STEP TO AN ADVANCED OXIDATION PROCESS MEDIATED BY SULFATE RADICALS"

 

PALAVRAS-CHAVES:

Atrazine. Zero-valent copper. Persulfate. UV radiation. Toxicity

PÁGINAS: 78
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
RESUMO:

The contamination of waterbodies by pesticides that are resistant to conventional water treatment processes consists a serious environmental problem, making urgent the development of alternative technologies capable of degrading them. Among these pesticides is Atrazine (ATZ), which is of special concern due to its endocrine disrupting character, being classified as a priority substance to be monitored for water quality purposes in the European Union. Advanced oxidation processes (AOP) have been pointed as a promising technology against these kind of pollutants. However, as an organochloride, ATZ contains electron-deficient groups, making it more easy to reduce than to oxidize. Therefore, a pre-reducing step is preferred to an oxidative one for the removal of these class of contaminants. Given that, in this study was investigated the application of zero-valent copper as a reducing agent for the degradation of ATZ. Then, this was combined with a sulfate radical (SO4●-)-driven AOP. To study the influence of different operational conditions in the pre-reducing step, a Doehlert experimental design was followed. Then, the mineralization of the solution that presented the highest ATZ degradation was studied by varying the oxidant concentration – sodium persulfate (1, 5 and 10 mmol L-1) – and the UV source of radiation (UVC and UVA). A toxicity assay with the microalgae Chlorella vulgaris was performed with the samples that obtained the highest degradation and mineralization results after each step. For the pre-reductive stage, the Doehlert design showed that the best conditions are those that combine low pH and high copper concentration (>0.2% m/V). The oxidative step was then applied on the most degraded solution and about 70% of mineralization was achieved after 2 hours of reaction when 5 mmol L-1 of persulfate and UVC radiation were used. Regarding toxicity assays, the reduced solution was 30% less toxic than the parent-ATZ solution. However, when the oxidative step was performed, a significant toxicity increase was observed. In this way, results indicate that a higher mineralization does not necessarily mean low toxicity and, therefore, additional studies are required to understand the relation between these effects in order to achieve a harmless solution to the microalgae.

MEMBROS DA BANCA:
Externo à Instituição - ANDERSON ALLES DE JESUS - UFRN
Interno - 2929066 - ANDRE LUIS LOPES MORIYAMA
Externo à Instituição - CÁTIA ALEXANDRA LEÇA GRAÇA - USP
Presidente - 1149554 - OSVALDO CHIAVONE FILHO