The main objective of this work is to investigate the role of two types of ionic liquids, omimBF4 and omimPF6, upon the microwave demulsification process. A series of batch demulsification runs were carried out to evaluate the final emulsified water content of emulsion samples after the exposure to microwaves at distinct ionic liquid concentrations. Tests were performed in a commercial microwave reactor system, using high stable water-in-crude oil emulsion samples containing different salt and water contents. Similar separation tests conducted under conventional heating were investigated for comparisons. Results showed that increasing the concentration of each ionic liquid yields improved demulsification results in both microwave and conventional heating processes. However, the microwave process was always much faster and more efficient than the conventional case. Blank tests without ionic liquid have not produced water separation, which indicates the high stability of the investigated emulsions. In particular, the joint use of omimPF6 (even at low concentrations) and microwave irradiation allows for system demulsification with high efficiency at short time, with some cases even reaching water contents in the range of 1−2% in the final emulsion.

The use of ionic liquids (ILs) as demulsifiers of water-in-crude oil emulsions represents a new field of study. The main purpose of this work is to investigate the effect of five ILs, [C 4 and a set of operation parameters on the demulsification process, including the heating type (conventional and microwave), IL concentration (0.74−8.9 μmol/g), effect of alkyl chain length, and effect of cation and anion type on demulsification efficiency. The results indicated that the demulsification was favored when more hydrophobic ILs and longer cation alkyl chains were employed, such as [C 12 mim] + [NTf 2 ] − , reaching values close to 92% of water removal. Moreover, the joint use of microwaves and hydrophobic ILs allowed us to maximize the demulsification efficiency.

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In this work, a comprehensive study was performed for the evaluation of ultrasound (US) frequency for demulsification of crude oil emulsions. Experiments were performed using ultrasonic baths operating at the following frequencies: 25, 35, 45, 130, 582, 862 and 1146kHz. Synthetic water-in-oil emulsions with 12%, 35% and 50% of water and medians of droplet size distribution (DSD, D(0.5)) of 5, 10 and 25μm were prepared using a heavy crude oil (API density of 19). Crude oil demulsification was achieved at frequencies in the range of 25-45kHz for all tested emulsions. When frequencies higher than 45kHz were applied, no changes in the characteristics of the crude oil emulsions were observed. Demulsification efficiencies of about 65% were achieved at a frequency of 45kHz after 15min of US application (emulsions with original water content of 50% and D(0.5)=10μm). An important aspect is that no addition of chemical demulsifiers was performed, and the demulsification efficiency was considered high, taking into account that the results were obtained using a non-conventional crude oil. Contrary to the normal application of low-frequency US that has been used for emulsification, the proposed approach seems to be a promising technology for water removal from crude oil emulsions.

Microwave radiation to promote the destabilization of water-in-crude oil petroleum emulsions is already an alternative technology for heating. Recent studies have suggested that microwave heating is more effective than conventional heating. This study assessed the following effects on the demulsification process: the aging of emulsions for the two types of heating (microwave and conventional), the time interval between microwave heating and the addition of a chemical demulsifier, and the time of microwave irradiation on the heating of petroleum and brine fluids. In addition, this study compared the efficiency of water separation by conventional heating and microwave heating regarding the (a) mean temperature of the emulsion and (b) temperature of water droplets. It was observed that water separation is less efficient for the two types of heating when the emulsion is subjected to aging. The efficiency of water separation using microwave heating is greater than with conventional heating when the mean temperature of the emulsion remains the same. However, they were equivalent when the temperatures of the water droplets are equal. This fact indicates that the advantage of selectively heating water droplets by microwave radiation is that the temperature of the treatment of emulsions can be reduced: the higher temperature that is located in region of interest (water droplets and the periphery) facilitates the drainage of the interfacial film and the stage of coalescence between the water droplets.