Microwave-Assisted Procedure for Salinity Evaluation of Heavy Crude Oil Emulsions

A procedure for salt extraction of heavy crude oil emulsions (API lower than 14°) was performed using microwave radiation. Emulsion was transferred to high-pressure quartz vessels with further water addition. Microwave radiation was applied for 60 min, and after separation of phases, chloride determination was performed in the water phase by ion chromatography (IC). The sampling procedure, heating time (10−40 min), microwave power (500−800 W), and the number of extractions (1−5) were evaluated. The salt remaining in the oil phase was determined, as chloride, by IC after sample digestion by a microwave-induced combustion technique, and the results confirmed the high efficiency of the proposed microwave-assisted salt extraction procedure. Using the proposed procedure, the salt extraction efficiency from heavy crude oil emulsion was higher than 95%. For a comparison of the results, Cl determination was also performed by inductively coupled plasma−optical emission spectrometry and potentiometric titration. The procedure allowed the salinity determination in less time (1 h) in comparison to the recommended ASTM D 6470 method (more than 4 h), and the use of toxic reagents or demulsifiers was avoided. Up to eight samples could be processed simultaneously, making the proposed procedure suitable for routine analysis in a laboratory scale.