Avaliação das incertezas associadas à determinação do parâmetro de solubilidade de Hildebrand de petróleos

Moura, Lyzette Gonçalves Moraes de; Rolemberg, Marlus Pinheiro; Ramos, Antonio Carlos da Silva; Santos, Dheiver; Zilio, Evaldo López

doi:10.1590/s0100-40422011000200011

Cited by 6 publications

(9 citation statements)

References 13 publications

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“…The literature also reports a value of 16.2 MPa 1/2 as a lower solubility parameter threshold for precipitation of asphaltenes by the addition of n -heptane. The value of 16.2 MPa 1/2 is usually applied in models of crude oil compatibility in which it is assumed that the asphaltenes start precipitating at the same destabilization parameter independent of the nature of the crude oil. , These results are also in agreement with those found here, since the asphaltenes in petroleum tend to be more stable than the A-C7I fraction in a model system due to the presence of molecules similar to those of C7I, but with lower polarities, helping to stabilize the more polar asphaltenes present in the oil. More stable systems precipitate with higher n -heptane concentrations, causing the solubility parameter at the precipitation onset to be lower than that observed in model system containing A-C7I.…”

Section: Resultssupporting

confidence: 87%

“…The asphaltenes are precipitated by the addition of a nonsolvent with higher solubility parameter than toluene, so for the A-C7I fraction the value of 18.7 MPa 1/2 represents the condition in which the molecules with lower solubility parameter leave the solution, such that this is the upper parameter limit for the destabilization of asphaltenes C7I. ,− …”

Section: Resultsmentioning

confidence: 99%

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Flocculation of Asphaltenes by Polymers: Influence of Polymer Solubility Conditions

et al. 2018

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Sulfonated polystyrene has shown flexible action as an asphaltene dispersant/flocculant as a function of the degree of sulfonation and concentration used. In this work, samples of sulfonated polystyrene with different sulfonation degrees were assessed in precipitation assays in model asphaltene systems, with variation of the asphaltene fractions (asphaltenes extracted by n-pentane and n-heptane, C5I and C7I, respectively), asphaltene concentration, polymer concentration, and medium used to dissolve the polymer and asphaltenes. The precipitation tests were carried out with an ultraviolet–visible spectrometer, and the absorbance values were converted into asphaltene concentration values in solution by using calibration curves. The results showed that the concentration of sulfonic groups at which the polymer performs best as an asphaltene flocculant is 10 mol %. The dependence of the polymer’s effect as a flocculant or stabilizer of asphaltenes in function of its hydrophilicity and concentration was confirmed. Moreover, the results indicate there is a strong relationship between the polymer’s solubility in the medium and its flocculant action, which is significantly more effective when the polymer does not have strong affinity for the medium.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Flocculation of Asphaltenes by Polymers: Influence of Polymer Solubility Conditions

et al. 2018

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“…The solubility parameter of asphaltenes is another very important aspect that is attracting growing research interest, because it can enable prediction of the factors that will cause precipitation and deposition of asphaltenes . Infrared (IR), near-infrared (NIR) and microcalorimetry techniques have been used to determine the solubility parameters of the various components of crude oil. − Besides this, compatibility models have been developed. − …”

Section: Introductionmentioning

confidence: 99%

Asphaltenes Precipitation Onset: Influence of the Addition of a Second Crude Oil or Its Asphaltenes Fractions (C3I and C5I)

et al. 2018

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Predicting the asphaltene stability in crude oils from different production streams is very useful in the petroleum industry because it allows avoiding serious problems caused by formation of solid deposits during oil flow. That prediction can be carried out by applying the solubility parameter (δ) of each oil, as calculated by the asphaltene precipitation onset value, obtained by titration with n-heptane. However, many crude oils do not have a well-defined precipitation onset point, which can be overcome by adding a crude oil assumed as the standard. This article analyzes the influence of a crude oil (called APS) on the precipitation onset of two other petroleum samples (called APA and APB). For this purpose, the asphaltene fractions C3I and C5I were extracted from APS, and the influence of the addition of this crude oil as well as its asphaltenes fractions in samples of oils APA and APB was evaluated by tests involving titration of n-heptane with detection by near-infrared spectroscopy (NIR). The calculation of the solubility parameters of the oils without well-defined precipitation onset, by adding the oil with well-defined precipitation onset, led to varied errors in function of the type of oil in question. The smallest errors were obtained when using, as the solubility parameter of the mixture (δM), the solubility parameter of the solvent system at the precipitation onset of the asphaltene C3I fraction (extracted from the crude oil assumed as the standard) in toluene, determined by titration with n-heptane.

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“…Since the sources of uncertainty and the measurand were mathematically related, the variation of the measurand (y) in relation to the variation of a given input source (x i ) was estimated by calculating the coefficient of sensitivity (Equation 5) (MOURA et al, 2011). 5Subsequently, the uncertainty component was estimated, with the same unit of the measurand, multiplying the sensitivity coefficient and the standard uncertainty of the input estimate.…”

Section: Estimation Of Measurement Uncertaintymentioning

confidence: 99%

Performance verification and measurement uncertainty estimation for the determination of sodium chloride in butter

Moura

Ribeiro

David

et al. 2019

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The minimum parameters of identity and quality of butters in Brazil are governed by the Ministry of Agriculture, Livestock and Supply. From them it is possible to carry out the performance verification of the methodologies to guarantee the results reliability. Thus, the objective of this study was to analyze the performance of the method of determination of NaCl in butter, based on ISO 1738:2004, evaluating accuracy, precision and the limit of quantification (LOQ). The precision was obtained since the coefficients of variation found in the tests were lower than the Horwitz value. The accuracy was approved as a consequence of the confirmation of the proficiency having as provider the FAPAS. The LOQ of 0.41g of NaCl/100g of butter was established by evaluating the accuracy and the recovery in a NaCl content determination test, using a solution prepared with Certified Reference Material. To assure quality, the uncertainty associated with the NaCl measurement was also estimated, through the evaluation of the possible sources of uncertainty, among which were: weighing, analyzer, glassware and the reagent purity, with a measurement uncertainty of 0.03g NaCl/100g of sample. Finally, it was verified the conformity of the NaCl content in commercial samples according to the Brazilian legislation.

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Avaliação das incertezas associadas à determinação do parâmetro de solubilidade de Hildebrand de petróleos

Cited by 6 publications

References 13 publications

Flocculation of Asphaltenes by Polymers: Influence of Polymer Solubility Conditions

Flocculation of Asphaltenes by Polymers: Influence of Polymer Solubility Conditions

Asphaltenes Precipitation Onset: Influence of the Addition of a Second Crude Oil or Its Asphaltenes Fractions (C3I and C5I)

Performance verification and measurement uncertainty estimation for the determination of sodium chloride in butter

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