The best performing membrane was co

The best performing membrane was compared with various published membranes for oil-in-water emulsion separations including polymeric, inorganic and composite membranes (Fig. 9, Table S7). The effectiveness of separation depends largely on the size of the emulsions, and therefore the permeance was normalized by the average droplet size of the emulsions. The membrane demonstrated excellent oil-removal efficiency at the expense of permeance. Only two membranes reported in the literature showed higher permeance, although we note that i) they were not tested with produced water (i.e., oil-in-water emulsion without salt), and ii) neither the long-term stability nor the antifouling properties and cleaning were assessed.