Abstract: The oil content in the polluted water can be decreased from hundreds ppm to dozens ppm throuth treating the emulsified water containing oil with magnetofluids or Fe₃O₄fine particles; The influences of properties of the fine particle and the surfactant on the purification were studied. The mechanism of waste water purification with Fe₃O₄fine particles and magnetofluids is also proposed.

Key words: Superfine particles, Magnetofluid, Polluted water