Preparation of a demulsifier using rice straw as raw materials via a simple acid treatment process

A low cost and environmentally friendly demulsifier (A-RS) was prepared using waste rice straw (RS) as starting materials via a simple acid treatment process. It was characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The influence of demulsifier dosage, temperature, settling time, pH value and salinity on the demulsification efficiency (DE) of water-in-crude oil emulsion were explored through bottle tests. The results displayed that the DE could reach 89.52% within one minute when the dosage of A-RS was 600 mg/L at 70 degrees C. The A-RS demulsifier had a good acid and alkali resistance, the DE could reach 92.72% and 86.32% when the pH value of emulsion was 2 and 10, respectively. Also, it had an excellent salt tolerance, and the DE increased slightly with the increase of the salinity. The demulsification mechanism was also investigated through interfacial activity, interfacial tension (IFT), wettability, formation of interfacial film and optimal microscopy. It is expected that A-RS has a great application prospect in the dehydration of crude oil.