ENHANCED MICROWAVE-HEATING OF NONPOLAR-SOLVENTS BY DISPERSED MAGNETICNANOPARTICLES

The microwave absorption characteristics of xylene as a model nonpolar solvent are dramatically increased by the incorporation of dispersed cobalt and magnetite nanoparticles. The addition of 1-2 vol % of these colloids to xylene can produce heating rates by microwaves at 2.45 GH z that approach those for water. The particles have diameters of 5-20 nm and contain a coating on their surface to avoid their aggregation a nd precipitation from solution. The small particle sizes are compatibl e with a rapid process of heat transfer to the surrounding xylene, the reby minimizing the generation of large temperature gradients around t he particles. Cobalt particles are more effective than magnetite parti cles for enhancing the heating rates of xylene by microwaves, with nan oparticles of cobalt with diameters less than 10 nm exhibiting greater levels of microwave absorption enhancement than nanoparticles of larg er diameters.