Surface modified polypropylene membranes for treating hydraulic fracturing produced waters by membrane distillation

Membrane distillation is an emerging technology for treating hydraulic fracturing flowback and produced waters (PW). Suppression of membrane fouling by inorganic and polar and non-polar organic compounds is a challenge. Here, polyhydroxyethyl methacrylate, polyacrylic acid, polvinylallyl imidazolium bromide and polyvinylhexyl imidazolium bromide chains have been grafted from the surface of polypropylene membranes. Fouling happens initially due to adsorption of organic compounds followed by scale formation. When challenged with PW, membranes modified with polvinylallyl imidazolium bromide chains provided the greatest resistance to fouling. For electrocoagulation pretreated PW and synthetic PW that contained mainly inorganic species, the flux decline was much less.