The major contaminant targeted during the treatment of the oilfield produced water is dispersed oil.The efficiency of most separation processes highly relies on the size of the droplets, which can be increased through coalescence. Crude oil has a complex and field-dependent composition, which can affect the interfacial properties of the drops, and consequently the merging process in different ways. This study focused on the development of microfluidic techniques for investigating coalescence between crude oil drops. The experiments were performed with six diluted crude oils and three neat oils, the latter in the presence of an oil-soluble surfactant. The composition of the water phase was systematically varied (pH, ionic composition, presence of dissolved components). In general, crude oil droplets coalesced more readily in lower or neutral pH. The addition of dissolved Fluka acids to the water phase had a unique effect on each crude oil, reflecting their composition.What is more, this effect was similar to the presence of water-soluble crude oil components in the aqueous phase. The pressure did not have a significant effect on the coalescence, which was explained by the lack of the lightest components (C1-C4) in the system. In summary, the results revealed several trends, however it was clear that the coalescence highly depended on the oil composition. This underlined the necessity for experimental methods, such as microfluidics, which allow for quick assessment of the stability of crude oil droplets.
Understanding the corrosion mechanisms and the effect of corrosion products on the basic properties of the salt (e.g., melting point, heat capacity) is fundamental for the safety assessment and durability of molten salt reactor technology. This work focused on the thermodynamic assessment of the CrF2−CrF3 system and the binary systems of chromium trifluoride CrF3 with alkali fluorides (LiF, NaF, KF) using the CALPHAD (computer coupling of phase diagrams and thermochemistry) method. In this work, the modified quasi-chemical model in the quadruplet approximation was used to develop new thermodynamic modelling assessments of the binary solutions, which are highly relevant in assessing the corrosion process in molten salt reactors. The agreement between these assessments and the phase equilibrium data available in the literature is generally good. The excess properties (mixing enthalpies, entropies and Gibbs energies) calculated in this work are consistent with the expected behaviour of decreasing enthalpy and Gibbs energy of mixing with the increasing ionic radius of the alkali cations.
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