The organic acids present in petroleum, commonly called “naphthenic acids” (NA), are identified
as carboxylic acids of the general formula “RCOOH”, where R represents a hydrocarbon chain
that does not necessarily show cycloaliphatic structure. The presence of stable oil-in-water
emulsions in the crude oils hinders the dehydration process, which is required during the
production step. Some compounds, such as the organic acids (NA) present in the crude oils, are
involved in the stabilization of the emulsions, because of their amphiphilic structure. The
emulsion-breaking process is improved if the organic acids are determined qualitatively and
quantitatively. We proposed the study of a quantitative extraction procedure of NA contained in
crude oils. First of all, we performed the liquid−liquid extraction of the organic acids, using
alcoholic solutions. Because this method did not allow the quantitative recovery of the acids, we
developed a separation process based on an ion-exchange resin (QAE Sephadex A25). The isolated
acid fraction was then derivatized as methyl esters and quantified by gas chromatography
experiments, using the internal standard method allowing the determination of the NA
composition. The extraction yield was checked via the total acid number (TAN) measurement,
using the standard ASTM D664-95 (IP 177/96), which is the standard method commonly used in
the oil industry. The extraction of NA on ion-exchange resins required the preliminary study of
a model molecule mixture of carboxylic acids, to ensure the complete control of the procedure.
Four crude oil samples that were provided by Total (France) (Y1, Y2, Y3, Y4) were then analyzed.
The results confirmed the presence of such acids in the crude oils.
The aim of this work was to study the solubility of hexafluorobenzene in aqueous salt solutions because,
despite its interest, information about the solubility of perfluorocarbons in aqueous solutions was
previously not available. The solubility of the perfluorocarbon in water and aqueous salt solutions was
measured using a liquid−liquid extraction method. The method was validated by comparing the measured
solubility of ethylbenzene in water with the literature data. The estimated uncertainty in the experimental
data is less than 6%. The effect of the salt concentration and the cation/anion effect on the solubility
were also established. Solubility data was measured in the temperature range from (280 to 340) K at
atmospheric pressure. Thermodynamic functions such as the Gibbs energy, enthalpy, and entropy of
solution were obtained from the temperature dependence of the solubility data. From the data on the
enthalpies of solution, values of the enthalpy of solvation in the solvents were determined and discussed.
The demand for fresh and clean water sources increases globally, and there is a need to develop novel routes to eliminate micropollutants and other harmful species from water. Photocatalysis is...
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