Mussel-inspired hydrophilic modification of polypropylene membrane for oil-in-water emulsion separation

During the water treatment process, the common polymer membranes with high interface energy are frequently contaminated by oily water. The wettability of the separation membrane surface greatly limits the application range of the membrane. Here, a facile method is reported to fabricate a hydrophilic and underwater superoleophobic coating on hydrophobic polypropylene (PP) microfiltration membrane via co-deposition of tannic acid (TA), polyethyleneimine (PEI), and dopamine (DA). After modification, the microfiltration membrane exhibits excellent hydrophilicity, outstanding acid, alkali and organic solvent resistance. In addition, they can be applied to separate n-hexane-in-water emulsions driven by self-gravity with excellent water flux (489 ± 24 Lm−2 h−1) and high separation efficiency (99.8%). The fabricated TA/DA/PEI coating with outstanding performances has great potential application in the field of oily water treatment.