Patent ID: 8329473

Claim:
A method for extracting polychlorinated biphenyls from an oily liquid containing polychlorinated biphenyls, comprising the steps of: adding the oily liquid to a sulfuric acid silica gel layer, allowing the sulfuric acid silica gel layer to which the oily liquid is added to be kept in a state heated to at least 35° C. for a predetermined time and then cooling the layer to ordinary temperature, supplying an aliphatic hydrocarbon solvent to the sulfuric acid silica gel layer cooled to ordinary temperature, allowing the aliphatic hydrocarbon solvent passed through the sulfuric acid silica gel layer to be supplied to, and passed through, a metal salt hydrate silica gel layer, allowing the aliphatic hydrocarbon solvent passed through the metal salt hydrate silica gel layer to be supplied to, and passed through, a silver nitrate silica gel layer, allowing the aliphatic hydrocarbon solvent passed through the silver nitrate silica gel layer to be supplied to, and passed through, an alumina layer, allowing a hydrophobic solvent capable of dissolving the polychlorinated biphenyls to be supplied to, and passed through, the alumina layer, and securing the hydrophobic solvent passed through the alumina layer, wherein a metal salt hydrate silica gel used in the metal salt hydrate silica gel layer is prepared by adding to silica gel an aqueous solution of a metal salt hydrate selected from the group consisting of copper sulfate hydrates, copper nitrate hydrates, calcium nitrate hydrates, and iron nitrate hydrates and then removing water by heating under reduced pressure.