Preparation and demulsification performance of modified attapulgite nanoparticle demulsifier

By chemically modifying the attapulgite (AT) using 3-Aminopropyl triethoxysilane (APTES), stearic acid (STA) and/or octadecyl trichlorosilane (OTS), AT-APTES, AT-APTES-STA and AT-OTS nanoparticle demulsifiers were prepared. The structure and morphology of the prepared materials were characterized and analyzed by FT-IR, SEM and Zeta potential. Contact angle characterization and the distribution of nanoparticle materials in the oil-water mixture showed that the AT-APTES-STA nanomaterial has good amphiphilicity and interfacial activity. The demulsification performance of various NP demulsifiers was investigated by using bottle test method. The results showed that the AT-APTES-STA nanoparticles can achieve rapid and efficient demulsification of the crude oil emulsions at room temperature in a wide pH range from acidic to weak alkaline. The increase of demulsifier dosage and demulsification temperature was helpful to improve the demulsification efficieny. However, the influence of temperature on the demulsification efficiency was limited, and good demulsification efficiency could be obtained at room temperature. Under the conditions of demulsifier dosage 900 ppm, pH 7 and temperature 25℃, the demulsification efficiency of AT-APTES-STA was as high as 96.7%. In contrast, the AT-APTES had a poor demulsification efficiency, while the AT and AT-OTS materials basically do not have the demulsification ability. By comparing the demulsification performance and the chemical structure of these modified attapulgite nanoparticles, it was concluded that a NP demulsifier with excellent demulsification performance should have the following two basic characteristics: (a) good amphiphilicity and interfacial activity; and (b) enough surface functional groups that can strongly interact with the emulsified molecules. It is believed that this work is of great significance to the design and preparation of NP demulsifiers for the crude oil emulsion.