The demulsification of crude oil emulsion driven by a natural lotus leaf grafted with nano-SiO2

An environmentally friendly LLP@SiO2 demulsifier was prepared by coating nano-SiO2 on the natural lotus leaf powder (LLP) via a simple hydrothermal method. Fourier-transform infrared spectroscope (FT-IR), field-emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscope (EDS) and thermal gravimetric analyzer (TGA) were employed to characterize the demulsifier. The effect of the LLP@SiO2 dosage, temperature, settling time, pH value and salt concentration on the demulsifying process was studied in detail. The bottle test results showed that the demulsification efficiency (DE) reached 83.78% within 1 min when the dosage was 600 mg/L at 70 °C. The DE could increase to 91.91% if the settling time was prolonged to 60 min. The LLP@SiO2 demulsifier had excellent acid and salt tolerance, and the high salinity also could improve the demulsification performance. It showed that the DE could maintain at 91.91% even at strong acid condition of pH = 2 and it increased to 94.33% when the salinity was increased to 20,000 mg/L. In addition, the possible demulsification mechanism was systematically studied by the interfacial activity, interfacial tension (IFT), wettability and microexamination.