Separation of oil–water emulsion by biomimetic polycaprolactone tannic acid hydrophilic modified membranes

The development of anti-fouling membrane materials was inspired by marine mussel organisms, as membrane surfaces with adhesive materials has enhanced anti-fouling properties. A polycaprolactone (PCL) substrate with superhydrophobic properties was prepared using electrospinning technology. Hydrophilic silane coupling agents KH560 and TEOS were modified on the substrate through the biomimetic adhesion of tannic acid. Surface superhydrophilic/underwater superoleophobic PCL membranes were prepared by a simple and low-cost preparation method, and the surface modification mechanism was further analyzed. The results demonstrated that the modified WCA decreased ultimately to 0°. The oil–water separation efficiency of the prepared superhydrophilic/underwater superhydrophobic PCL composite membrane was 99.94 % and 98 %, respectively, tested using standard simulated oil and crude oil emulsions, with fluxes of 6000 L m −2  h −1 , 5850 L m −2  h −1 , demonstrating effective separation of various oil–water emulsions. The results revealed changes of crystal morphology in membrane materials before and after modification, as well as membrane’s thermal stability under high temperatures. The mechanical properties of the composite membrane were assessed using a tensile tester. Changes in surface morphology and roughness were investigated using SEM and AFM. After 20 times oil–water separations, the membrane demonstrated a consistent over 99 % separation efficiency. which demonstrated that the membrane exhibits excellent stability and resistance to oil.