Preparation of demulsifying functional membrane and its application in separation of emulsified oil

Oil-water emulsion is a stable and complex system, which is harmful to our life if not treated properly. Membrane technology is an effective method to treat oily wastewater. In this work, composite modified poly(vinylidene fluoride) (PVDF) membrane with a hydrophilic layer concluding hydroxyl groups and polyether structure is rationally fabricated via grafting methoxypolyethylene glycol (MPEG) and lactobionic acid (LA) simultaneously. Compared with membranes modified by a single MPEG or LA, the optimal composite membrane possesses excellent hydrophilicity(water contact angle of 0 degrees), underwater hydrophobicity (underwater oil contact angle of 159 degrees), and anti-fouling. Due to the polyether structure of MPEG, the composite membrane exhibited emulsion breaking ability and can be used for effective separation of oil-in-water emulsions stabilized by different surfactants (sodium dodecyl sulfate (SDS), Tween-80 and cetyl trimethyl ammonium bromide (CTAB)). In addition, the composite MPEG-LA layer exhibited good stability, proving that the modified membrane can be used in real harsh environments. The modified strategy is a good solution for construction of functionalized membrane for practical oil/water separation.

Automated summary

The composite modified PVDF membrane with a hydrophilic layer was successfully fabricated, showing excellent hydrophilicity, anti-fouling properties, and emulsion breaking ability for efficient separation of oil-in-water emulsions stabilized by different surfactants.