Magnetically recoverable efficient demulsifier for water-in-oil emulsions.

A magnetically recoverable and efficient demulsifier is shown to demulsify surfactant-stable water-in-oil emulsions rapidly. Ferroferric oxide (Fe3 O4 ) particles are firstly coated by amorphous silicon dioxide (SiO2 ), and further functionalized with a commercial dodecyltrimethoxysilane solution (KH-1231). Owing to their paramagnetic properties, the demulsifier particles can be easily recovered with a magnet. Upon addition of demulsifier to emulsions and subsequent sonification, the supernatant becomes completely transparent and no droplets are observed in the micrographs. It was also demonstrated that this demulsifier is effective for emulsions prepared with a variety of oils. Moreover, magnetically recovered demulsifier can be recycled after simple treatment without any decline of efficiency. This work presents a feasible approach for demulsifying water-in-oil emulsions, and has potential value in industry.