Polymer composite, water-treatment method using the same and manufacturing method of the same

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 (m2/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/cm3) presents density of the polymer;
• and
• F (%) represents a content rate of the polymer to a whole weight of the polymer composite.