Banca de DEFESA: LUANA RABELO HOLLANDA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUANA RABELO HOLLANDA
DATA : 23/07/2018
HORA: 09:00
LOCAL: Auditório do NUPEG
TÍTULO:

STUDY OF ATRAZINE PESTICIDE DEGRADATION THROUGH COPPER REDUCTION IN VALENCIA ZERO, AND OF ITS POTENTIALITY AS A PRE-STEP TO PHOTO-OXIDATION WITH PERSULFATE

 

PALAVRAS-CHAVES:

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

PÁGINAS: 88
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
ESPECIALIDADE: Processos Orgânicos
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 this kind of pollutant. 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). During the oxidative stage, samples were collected after 30, 60 and 120 minutes of reaction. Toxicity assays with the microalgae Chlorella vulgaris and the bacteria Vibrio fischeri were 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 with C. vulgaris, the reduced solution was 30% less toxic than the parent-ATZ initial solution. For the test with V. fischeri, it was found that ATZ initial solution did not cause inhibitory effects, but a significant increase in toxicity was observed after the reductive step. For both organisms, it was verified that, among the three reaction times tested, the toxicity reached a minimum value after one hour of reaction of the pre-reduced solution with persulfate. However, for longer reaction times the toxicity has increased again, even though higher mineralization values were achieved. 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.

MEMBROS DA BANCA:
Externo à Instituição - ANDRE LUIS NOVAIS MOTA - UFERSA
Externo à Instituição - ANDRESSA BASTOS DA MOTA LIMA - USP
Externo à Instituição - CÁTIA ALEXANDRA LEÇA GRAÇA - USP
Presidente - 1149554 - OSVALDO CHIAVONE FILHO