Patent ID: 8540883

Claim:
A water-treatment method using a polymer composite, the polymer composite comprising: secondary aggregates, the secondary aggregates being formed of clumped particles, the particles being magnetic particles covered with a polymer, wherein a mean diameter of the magnetic particles is not less than 0.05 μm and not more than 100 μm, the method comprising: dispersing the polymer composite in water containing impurities; making the polymer composite adsorb the impurities to surfaces of the polymer composite; and separating the polymer composite adsorbed the impurities by using magnetic forces, wherein C, D, X, E and F satisfy a relationship of 0.001≦F/(C×D×E)≦X, where C (m 2 /g) represents a specific surface area of the magnetic particles; D (%) represents a content rate of the magnetic particles to a whole weight of the polymer composite; X (μm) represents a mean diameter of the magnetic particles; E (g/cm 3 ) presents density of the polymer; and F (%) represents a content rate of the polymer to a whole weight of the polymer composite.