Flux-enhanced hierarchical porous membrane for oil-water nanoemulsion separation

Abstract

Hierarchical porous membranes suitable for use in oil/water separation processes are provided. The membranes described herein are particularly well suited for separating trace amounts of water (e.g., no greater than 3 wt % water content, no greater than 1 wt % water content, or 50-1000 ppm water) from oil in droplets less than 1 um in size. The membranes have a wide range of applications, including deep seep oil exploration, oil purification, and oil spill cleanup.

What is claimed is: 
     
         1 - 12 . (canceled) 
     
     
         13 . A method of preparing a hierarchical porous membrane suitable for use in an oil/water separation process, the method comprising: (a) combining a polymer, a pore former, and a solvent to make a polymer solution; (b) following step (a), allow the solution to sit for a predetermined time (e.g., 12 hours) at a predetermined temperature (e.g., 50.degree. C.) to allow release of air bubbles; and (c) casting a thin layer (e.g., on the order of 100-500 microns) on a plate (e.g., glass plate) and immersing the plate into a solution (e.g., water at room temperature) to undergo coagulation, thereby forming the hierarchical porous membrane; (d) optionally, rinsing the hierarchical porous membrane in a second solution (e.g., water for a predetermined time period, e.g., 24 hours); and (e) optionally, immersing the hierarchical porous membrane in a third solution (e.g., 1:1 glycerol-water solution for a predetermined time period, e.g., 24 hours). 
     
     
         14 . The method of  claim 13 , wherein the polymer is selected from the group consisting of polycarbonate, polysulfone (PSf), polyacrylonitrile (PAN), polyethersulfone (PES), and any combination thereof. 
     
     
         15 . The method of  claim 13 , wherein the solvent comprises dimethyl acetamide (DMAc), n-methyl-2-pyrrolidone (NMP) or a mixture thereof. 
     
     
         16 . The method of  claim 13 , wherein the pore former comprises poly(vinylpyrrolidone) (PVP), polyethylene glycol (PEG), or a mixture thereof. 
     
     
         17 . The method of  claim 13 , further comprising the step of performing plasma etching to remove at least a portion of a first layer of the membrane. 
     
     
         18 . The method of  claim 13 , wherein the plate is a glass plate. 
     
     
         19 . The method of  claim 13 , wherein step (b) further comprises curing the solution in water to allow release of the air bubbles.