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Previous issue date: 2012-07-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Actually in the oil industry biotechnological approaches represent a challenge. In that,
attention to metal structures affected by electrochemical corrosive processes, as well as
by the interference of microorganisms (biocorrosion) which affect the kinetics of the
environment / metal interface. Regarding to economical and environmental impacts
reduction let to the use of natural products as an alternative to toxic synthetic
inhibitors. This study aims the employment of green chemistry by evaluating the stem
bark extracts (EHC, hydroalcoholic extract) and leaves (ECF, chloroform extract) of
plant species Croton cajucara Benth as a corrosion inhibitor. In addition the
effectiveness of corrosion inhibition of bioactive trans-clerodane dehydrocrotonin
(DCTN) isolated from the stem bark of this Croton was also evaluated. For this
purpose, carbon steel AISI 1020 was immersed in saline media (3,5 % NaCl) in the
presence and absence of a microorganism recovered from a pipeline oil sample.
Corrosion inhibition efficiency and its mechanisms were investigated by linear sweep
voltammetry and electrochemical impedance. Culture-dependent and molecular
biology techniques were used to characterize and identify bacterial species present in
oil samples. The tested natural products EHC, ECF and DCTN (DMSO as solvent) in
abiotic environment presented respectively, corrosion inhibition efficiencies of 57.6%
(500 ppm), 86.1% (500 ppm) and 54.5% (62.5 ppm). Adsorption phenomena showed
that EHC best fit Frumkin isotherm and ECF to Temkin isotherm. EHC extract (250
ppm) dissolved in a polar microemulsion system (MES-EHC) showed significant
maximum inhibition efficiency (93.8%) fitting Langmuir isotherm. In the presence of
the isolated Pseudomonas sp, EHC and ECF were able to form eco-compatible organic
films with anti-corrosive properties / Na ind?stria petrol?fera problemas relacionados a processos corrosivos em estruturas
met?licas representam um desafio voltado para quest?es biotecnol?gicas. Esses
processos podem ser significantemente influenciados pela presen?a de
microorganismos que afetam a cin?tica eletroqu?mica da interface ambiente/superf?cie
met?lica (biocorros?o). Neste contexto, a substitui??o de inibidores sint?ticos t?xicos
por produtos naturais bioaceit?veis constitui uma alternativa economicamente
importante com minimiza??o de impactos ambientais. No presente trabalho um dos
objetivos principais est? vinculado ao emprego de qu?mica verde, em que foram
avaliados extratos da casca do caule (extrato hidroalco?lico denominado de EHC) e
folhas (extrato clorof?rmio, ECF) da esp?cie vegetal Croton cajucara Benth. Em
adi??o a efic?cia de inibi??o ? corros?o do clerodano bioativo trans-desidrocrotonina
(DCTN) isolado das cascas do caule deste Croton tamb?m foi avaliada. Para tanto,
utilizou-se a?o carbono AISI 1020 imerso em solu??o salina, sob influ?ncia de
microrganismo recuperado de uma amostra de petr?leo, bem como na sua aus?ncia. As
efici?ncias de inibi??es ? corros?o e seus mecanismos foram investigados atrav?s das
t?cnicas de voltametria de varredura linear e imped?ncia eletroqu?mica. T?cnicas
dependentes de cultura e de biologia molecular foram utilizadas na identifica??o de
esp?cies bacterianas presentes em amostras de petr?leo. Os extratos EHC, ECF e o
composto DCTN veiculados em DMSO, apresentaram respectivamente, efici?ncias de
inibi??es ? corros?o em meio abi?tico, com m?ximas de 57,6% (500 ppm), 86,1% (500
ppm) e 54,5% (62,5 ppm). Com rela??o ao processo de adsor??o, EHC se ajustou a
isoterma de Frumkin e ECF a isoterma de Temkin. No entanto, o extrato EHC (250
ppm) veiculado em uma microemuls?o polar (SME-EHC) com efici?ncia m?xima de
inibi??o 93,8%, se ajustou a isoterma de Langmuir. Na presen?a da esp?cie bacteriana
caracterizada Pseudomonas sp., os extratos EHC e ECF formaram filmes ecocompat?veis
protetores com a??o anti-corrosiva
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/13021 |
| Date | 31 July 2012 |
| Creators | Felipe, Maria Beatriz Mesquita Cansan??o |
| Contributors | CPF:13893734449, http://lattes.cnpq.br/2791074318745945, Huitle, Carlos Alberto Martinez, CPF:01139059980, http://lattes.cnpq.br/2485073932883264, Tonholo, Josealdo, CPF:16392398805, http://lattes.cnpq.br/6333407087554681, Souza, K?tia Regina, CPF:65561988468, Maciel, Maria Aparecida Medeiros, CPF:37320165449, http://lattes.cnpq.br/5360188002708095, Medeiros, S?lvia Regina Batistuzzo de, CPF:32398336468, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4781004Y8, Silva, Djalma Ribeiro da |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ci?ncia e Engenharia do Petr?leo, UFRN, BR, Pesquisa e Desenvolvimento em Ci?ncia e Engenharia de Petr?leo |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/embargoedAccess |
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