Banca de DEFESA: RUZA GABRIELA MEDEIROS DE ARAUJO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : RUZA GABRIELA MEDEIROS DE ARAUJO
DATA : 01/07/2016
HORA: 14:00
LOCAL: Sala de aula do LAPET
TÍTULO:
EVALUATION OF CARBOXYMETHYLCHITOSAN AS SCALE AND CORROSION INHIBITOR IN OIL WELLS
PALAVRAS-CHAVES:
Carboxymethylchitosan, scale inhibitor, corrosion inhibitor
PÁGINAS: 86
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Polímeros e Colóides
RESUMO:
The use of environmentally friendly products is an issue under discussion in many industrial operations. The biodegradability and ecotoxicity of the products used in the oil industry are of great relevance, and scale and corrosion inhibitor could not be an exception. Chitosan, a derivative of biopolymer chitin, which is mainly present in the shells of crustaceans, has great potential for this application as its structural and functional properties allow chemical structural modification that promotes the ability of complexing metals. Thus, the main objective of this study was to synthesize, characterize and evaluate the performance of carboxymethylchitosan (CMC) to inhibit calcium carbonate and barium sulfate precipitation, as well as corrosion inhibitor of chlorides in 1020 carbon steel, taking into account the conditions of temperature, pressure and salinity of oil wells in the Northeast of Brazil. The results showed that CMC acts as a good CaCO3 scale inhibitor, determined by dynamic efficiency test pressure of 1,000 psi and a temperature of 70 °C. The CaCO3 precipitation happened at approximately 15 min in the absence of CMC and at 50 minutes in the presence of 50 ppm of CMC. In addition, no change of pressure was observed at 170 ppm of CMC. Therefore, 170 ppm was considered the minimum effective concentration of CMC. However, CMC did not show up efficiency as precipitation inhibitor for BaSO4, because the precipitation time of BaSO4 in the absence and in presence of CMC were similar. The chronoamperometry data for precipitation of CaCO3 showed a reduction in the variation of cathode current, which can be related to the CMC interaction with the calcium ion, preventing the access of ions to the electrode surface. The SEM images showed distortion of the CaCO3 crystals in the presence of CMC, whereas for BaSO4 no significant modification was observed. The CMC also showed good properties as corrosion inhibitor in media containing Cl-, due to its tendency to move the corrosion potential towards more positive regions with the increase of polymer concentration, thus being classified as an anodic inhibitor. According to the extrapolation of Tafel curve, CMC presented inhibitory efficiency of about 80%. By using electrochemical impedance technique, the efficiency was about 67%. In both cases, the concentration used was 80 ppm. This efficiency was attributed to physisorption mechanism, as indicated by DGads value near to -10 KJ/mol.
MEMBROS DA BANCA:
Interno - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externo à Instituição - JOSEALDO TONHOLO - UFAL
Interno - 1804366 - JULIO CEZAR DE OLIVEIRA FREITAS
Externo à Instituição - MARCOS ANTONIO VILLETTI - UFSM
Presidente - 1149440 - ROSANGELA DE CARVALHO BALABAN