Demulsification of a New Magnetically Responsive Bacterial Demulsifier for Water-in-Oil Emulsions

A new, magnetically responsive bacterial demulsifier (MRBD) was prepared by grafting magnetite (Fe3O4) nanoparticles onto the surface of demulsifying cells. The demulsification process and performance of the MRBD were investigated using a Turbiscan system. At a mass ratio of magnetite to demulsifying cells of 0.2, the demulsification ratio of MRBD increased from 70 to 80% in the presence of a magnetic field, the demulsification half-life decreased from 3.0 to 2.0 h, and the transmitted intensity increased 4 times compared with the native bacterial demulsifier. Analysis of the demulsification process revealed, that an increased mass ratio improved the extent of drop coalescence by adjusting the balance between the surface hydrophobicity and magnetic responsiveness. The magnetic field mainly increased the drop sedimentation rate. The MRBD exhibited good recyclability and could be reused for three cycles, which may minimize demulsification costs. The simple synthesis and highly efficient demulsification performance represents a significant improvement over existing techniques.