Method for separating nonpolar hydrocarbon from water

A method of separating a nonpolar hydrocarbon from water, comprising:

• contacting the water with a composite material,
• wherein the composite material adsorbs 8-25 times its weight of the nonpolar hydrocarbon;
• wherein the composite material comprises:
• a polyurethane foam comprising an open-cell structure having an exterior surface and containing pores having an interior pore surface;
• a coating layer of reduced graphene oxide (r-GO) on at least 70% of a total of the exterior surface and the interior pore surface and in contact with the polyurethane foam, wherein the r-GO layer is in the form of nanoplatelets having a thickness of from 40 nm to 110 nm, a diameter of from 5 μm to 45 μm and a length to thickness aspect ratio of from 40:1 to 1,200:1;
• and
• a layer of polystyrene in contact with both the surface of the layer of r-GO and directly in contact with the surface of the polyurethane foam, wherein an average thickness of the polystyrene layer is from 500 nm to 4.5 μm;
• and
• wherein the composite material has pore diameters in a range of 50-500 μm.