Synthesis of Green Polyethylene Glycol-Lauric Acid Demulsifier from a Natural Source and Its Application in Demulsification of Field Emulsion: Experimental and Modeling Approach

Abstract

Green demulsifier was synthesized through an esterification technique by using polyethylene glycol (PEG) and fatty acid (lauric acid). The synthesized demulsifier was characterized through several tests to analyze the functional groups and determined the molecular structure, thermal stability, and biodegradability of the demulsifier molecule. The performance of the synthesized demulsifier was investigated using the standard static bottle test method to break the water-in-oil (W/O) tight emulsion. Optical microscopic and viscosity studies of emulsions were also performed to understand the demulsification process and mechanism. Based on the response surface method (RSM), central composite design (CCD) was used to develop the statistical model of demulsification efficiency by considering the four most influencing factors—demulsifier concentration, water content, settling time, and temperature—and to examine the optimal condition for maximum water separation from the emulsion. The statistical model’s accuracy and significance were evaluated using analysis of variance (ANOVA) and diagnostic plots. The effect of each factor was analyzed through 3D graphs and contour maps. The result indicates that all the factors significantly influenced the demulsification efficiency with a p-value of <0.0001, among which the presence of water is the dominating variable. At the optimal condition, the lauric acid-PEG-demulsifier (LPED) achieves a maximum demulsification efficiency of 95% in 30.9 minutes. Furthermore, the percent absolute deviation was computed after comparing the experimental findings to those predicted by the model and it was observed that the model’s prediction accuracy was >97%. Finally, the biodegradability test results showed that the developed demulsifier is completely biodegradable in 21 days. Because the synthesized demulsifier is eco-friendly and has an excellent dehydration rate, it may be used in the petroleum industry for breaking field-tight emulsions as an alternative to chemical demulsifiers.