Gravity assisted super high flux microfiltration polyamide-imide membranes for oil/water emulsion separation

Oil/water separation is a critical global challenge due to the ever-increasing generation of oily wastewaters from industrial activities and daily life. Membrane separation processes can effectively remove oil from water; however, synthesizing energy-efficient and anti-oil fouling membranes remains a huge enigma among researchers. In this work, we prepared novel polyamide-imide (PAO microfiltration membranes using our recently developed hydrogel-facilitated phase separation (HFPS) technique and conventional nonsolvent induced phase separation (NIPS) method. The external surface of the hydrogel mold could be patterned as desired. The prepared membranes, including HFPS-patterned, HFPS-unpatterned, and NIPS, showed high porosity, superhydrophilicity, and underwater superoleophobicity. The underwater oil contact angles of n-hexadecane and mineral oils were higher than 150 degrees, while a complete repellency for diesel oil was observed for all membranes. The ultra-high-water flux of patterned HFPS membranes, 440 L m(-2) hour(-1) (LMH), made them outstanding candidates for separating oil/water emulsions. For all fabricated membranes, gravity-driven filtration experiments of 9 consecutive oil cyclic filtration tests yielded >99.9% oil removal efficiency. Moreover, after 18 filtration experiments, the flux recovery ratio and flux decline were in the range of 90-100% and 3-20%, respectively.

Automated summary

Through the use of hydrogel-facilitated phase separation technique, researchers successfully developed polyamide-imide microfiltration membranes that exhibit high oil removal efficiency, ultra-high water flux, and excellent anti-oil fouling properties. These membranes provide a promising solution to the challenge of oil/water separation.