Non-oxidized metallic copper particles were prepared by plasma irradiation into aqueous solution of cupric sulfate in the presence of gelatin as a protective agent using home-made microwave induced plasma equipment. Then, two different steric structures of ascorbic acid, L-ascorbic acid and isoascorbic acid, were added as reducing auxiliaries. In the case of isoascorbic acid addition, metallic copper particles were obtained by plasma irradiation within about 5 minute. This result suggests that the reduction of copper ion from Cu2+ to metallic Cu can be succeeded by hydrogen radical generated by plasma in water combination with isoascorbic acid, and without toxic chemical agent such as hydrazine. Additionally, the diameter of copper particles can be controlled by the mount of CuSO4•5H2O and gelatin. These results were indicated that the plasma in liquid process has possibilities for high-speed and low environmental load process to prepare metallic copper particles.
