Demulsification of water-in-oil emulsions applying Fe3O4 magnetic nanoparticles for demulsifier modification: Experimental optimization via response surface methodology

Abstract

The Water-in-Oil (W/O) emulsions will cause serious problems in the operation, maintenance, and transportation of the petroleum industry. The presence of asphaltenes in crude oil intensifies the stability of this emulsion. In the current study, reusable Fe3O4 magnetic nanoparticles (MNPs) as a modifier for a commercial demulsifier were investigated to improve the demulsification of W/O emulsions with high asphaltenes content (13 wt%). Fe3O4 MNPs have been selected due to low consumption and cytotoxicity, most importantly, synthesis them by a facile and cost-effective electrochemical method. The research was carried out experimentally through bottle test methods and modeling via response surface methodology (RSM). The individual and reciprocal effects of five independent variables of temperature (T), concentration demulsifier (XD), pH, water content (WC), and nanoparticle dosage (ND) were analyzed on the percentage of demulsification efficiency (DE (%)) by a full quadratic polynomial model. The results showed that ND, pH, and WC, out of the ranges of the studied variables, had significant effects on DE (%), respectively. According to the results from statistical analyses, the highest DE (%) was 97.83% in optimal conditions: T of 40 °C, XD of 300 ppm, pH of 6.4, WC of 7.5 ml, and ND of 0.033 gr. Eventually, Fe3O4 MNPs can be reused at least three times successfully. Furthermore, by applying them in addition to the commercial demulsifier, DE (%) could be increased 10%, and the settling time decreased by 6 h. Consequently, the results indicated that the required settling time was significantly less than the conventional chemical demulsification. It reveals the high ability and performance of Fe3O4 MNPs in the W/O demulsification process.