Self-assembly and epitaxial growth of multifunctional micro-nano-spheres for effective separation of water-in-oil emulsions with ultra-high flux

Despite significant progress in synthesis and application of oil/water separation materials, the separation of water-in-oil emulsions is still a challenge until now, the separation materials are usually lowly resistant to intrusion pressure and susceptible to oil fouling. In this work, it is the first time that we report a novel metal-polybenzoxazine micro-nano-spheres (M-PBZs) for highly effective separation of water-in-oil emulsions with ultra-high flux. The superhydrophobic/superoleophilic surface with robust micro- and nano-scale two-tier structures was formed spontaneously on the M-PBZs through metal ion-induced molecule's self-assembly and epitaxial growth method. The resultant surface materials possess rapid oil absorption capacity, low density (38 mg/cm3) and high stability. And more interestingly, these M-PBZs can be used to separate multiple surfactant-stabilized water-in-oil emulsions effectively under gravity or intrusion pressure, achieving a high separation efficiency with >99.95% oil purity after filtration and an ultra-high oil flux far water-in-oil emulsions separation. Meanwhile, the M-PBZs' advantages of easy to disassemble and clean lead to excellent antifouling and good reusability.