Application of magnetite sols in environmental technology

Abstract

Theoretically and experimentally, it could be shown that 10 nm magnetite particles can be stabilized in aqueous carriers by electrostatic and/or Born repulsion, also under action of external magnetic fields. The bare or monolayer and bilayer covered particles can be used in environmental protection to eliminate dangerous components from waste water, polluted air and soil by adsorption, and extraction or heterocoagulation in combination with magnetophoresis of the modified magnetite particles in presence of an external magnetic field. A mixture of water and the ammonium salt of a perfluoropolyether (PFPE)-acid was used to determine the adsorption capacity of stable dispersed, positively charged magnetite particles. Under the condition of monolayer formation the PFPE-salt can be nearly totally eliminated from the water carrier. At bilayer formation the adsorption capacity is increased two fold, but there is an equilibrium between the adsorbed and in the carrier solved PFPE salt.