Green polymeric surface active agents for crude oil demulsification

The present work aims to develop a class of "green" demulsifiers for effective demulsification process. In this respect, six chitosan-based nonionic surfactants were prepared by chemical modification of chitosan with two aliphatic fatty acids, namely, lauric and stearic. The products were then reacted with polyethylene glycol (PEG 400, 1000 and 2000 g/mol) to produce ether amides surfactants. The prepared surfactants were characterized by IR spectroscopy and their thermal properties were investigated. It was found that the thermal stability of the prepared surfactants increase by increasing the length of PEG chain. Surface properties of the prepared surfactants were calculated through surface tension measurements at different temperatures. Furthermore, the demulsification efficiency of the prepared surfactants was verified under different conditions. Also, maximum water separation was achieved at 45 °C, neutral medium and low salt concentration. Viscosity of crude oil before and after demulsification was used as a parameter for demulsification process. Moreover, the demulsification process achieved by the green demulsifiers was monitored by the optical microscope.