Emulsion stability with nanoparticles and utilization of demulsifiers for break-up

Abstract

A state-of-the-art Portable Dispersion Characterization Rig (P-DCR) is used to generate emulsions with Exxsol mineral oil, commercial distilled water, as well as hydrophilic and hydrophobic silica nanoparticles (NP) as emulsifiers. The emulsion is prepared in the P-DCR batch separator vessel, whereby the separation kinetics are observed and recorded. In this study, two data sets are acquired, as follows: 1) Emulsion stabilization utilizing nanoparticles (Data Set I); and 2) Emulsion break-up using demulsifiers (Data Set II).Data Set I includes experiments conducted with mineral oil and distilled water as test fluids, and spherical silica nanoparticles of 20 nm mean diameter at concentrations of 0.01% and 1% by weight. The emulsions are created at a rotational speed of 600 RPM and at three water-cuts of 25%, 50% and 75%. Data for the hydrophobic particles, dispersed initially in the oil phase, confirm that highest emulsion stability is obtained with 25% water-cut, and only oil creaming occurs, while the emulsion is very resistant to water coalescence and sedimentation. The data also show that the separation rate improves with increasing water-cut to higher values. The second phase of Set I experiments includes the effects of hydrophilic nanoparticles, where the particles are initially dispersed in the water phase. The data demonstrate that in contrast to the hydrophobic particles, fast separation occurs at 25% water-cut, and increasing water-cut resulted to slower oil creaming process. Emulsions with combination of hydrophilic and hydrophobic particles is the last phase of the Data Set I. The data show that similar behavior as hydrophobic particles is observed, which emphasizes the dominant role of the hydrophobic particles as compared to hydrophilic ones. The experimental data for all cases show that increasing particle concentration results in more stable emulsions.The emulsion (base case) break-up using demulsifiers data (Data Set II) are acquired with 25% water-cut and 0.01% w/w hydrophobic NP utilizing 3 commercial demulsifiers, namely, ALKEN 860, ALKEN 862 and DB 964 with concentrations of 100, 500, 1000, 2000 and 4000 ppm. It is evident that the different chemical compositions of the demulsifiers produce different separation behavior. In general, an increase of the demulsifier concentration leads to an improvement of the emulsion separation. The recommended demulsifier for break-up of the base case emulsion is ALKEN 862 with a concentration of 500 ppm, which results in a fast and almost complete separation.