Patent ID: 7618540

Claim:
A flocculant for use in separating oily components contained in an oil-in-water type or a water-in-oil type emulsion containing suspended matter and dissolved sludge when 0.01 to 10 wt % of said flocculant is added to said emulsion said flocculant is a water soluble polymer having a chemical formula MO 3 —SO—R—OSO 3 M, said polymer unit R consisting essentially of: a unit (i) and a unit (ii) represented by the following formulas: wherein M is hydrogen or a metal element, R 3 and R 6 are each hydrogen or an alkyl group, and having a ratio per molecule of two units (i):(ii) being (1 to 100):(1 to 100), wherein the —OSO 3 M groups, in which M is hydrogen or a metal element, wherein said flocculant is made by polymerizing monomers with a larger amount of peroxodisulfuric acid salt than the amount of an initiator that is used; wherein an ultimate viscosity of the flocculant is 0.001 to 0.6 dl/g as determined by dissolving a sample in a 2 mol/l KBr solution measured at 25° C.