A composite membrane based on ball type copper phthalocyanine (Cu-Pc) compounds having oil rejection rates of 98% and more when fluid mixtures of oil and water are passed through the membranes under transmembrane pressures of 1 to 3 bar. Higher performance can be attributed to the presence of ball type copper phthalocyanine compounds in the membrane matrix that enhances the hydrophilicity of the membranes.

Methods of producing membranes, and membranes for metal and/or hydrocarbon removal. The methods include synthesizing an amine-modified metal oxide, wherein the amine-modified metal oxide comprises a metal oxide component and a water-soluble amino acid derivative having a 1:1 ratio of metal oxide components to water-soluble amino acid derivative; dissolving a water-soluble polymer and a polyvinylidene fluoride and the amine-functionalized metal oxide to form a polymer solution; casting the polymer solution into a mold to form a substrate membrane; coating the substrate membrane with a polyamide; and forming a membrane, wherein the amine-functionalized metal oxide is covalently connected to the polyvinylidene fluoride.

A hollow fiber membrane comprising polyethersulfone, wherein the hollow fiber membrane has a structure that is non-uniform in a thickness direction, and a gradient index which is a ratio of an average pore size at an inner surface side in a cross section of the hollow fiber membrane to an average pore size at an outer surface side in the cross section is 2.00 or more.