Patent ID: 8764992

Claim:
A method of fractionating a dispersion comprising predominantly oxidic nanoparticles and also coarser oxidic particles, thereby obtaining a finer fraction of oxidic nanoparticles, the method comprising filtrating via a membrane cross rotation filtration device, which comprises causing the dispersion to flow over a membrane by driven rotating parts, wherein the membrane cross rotation filtration device comprises a filtration media part and a rotor part that are stacked one above the other in a sandwich formation, and the membrane cross rotation filtration device further comprises a rotation shaft that drives the rotor part, the rotation shaft positioned in the middle of the sandwich formation, wherein the dispersion is stirred directly over the membrane, wherein the dispersion is caused to flow over the membrane with an average flow velocity of between 5 and 25 m/s, and wherein said filtrating produces a retentate and a filtrate, and said finer fraction of oxidic nanoparticles is present in the filtrate.