Koichi Nagafuchi¹, Atsushi Nagira¹, Hidenori Akiyama¹, Mitsuru Sasaki^1,, Kunio Kawamura²

Supercritical carbon dioxide and electric discharge plasma could be one of reaction or extraction media for green chemical processes. Supercritical fluid is an attractive solvent due to its unique characteristic and transport physical properties. Taking advantage of these characteristics, this has been extensively investigated for extraction and chemical conversion technology. Although density of a supercritical fluid is high like a liquid, it is mobile like a gas because of low viscosity. On the other hand, the electron energy generated by electric discharge plasma in high pressure and a high-density domain generally serves as an index depending on the field intensity and medium density which were supplied to electric discharge space. From the above-mentioned viewpoint, the synergistic effect of combining electric pulsed plasma and supercritical fluids is expected as a new reaction process which may be able to enhance chemical reaction without using any catalysts. In this research, production of protein-like substance by pulse electric discharge plasma was carried out using amino acid in supercritical carbon dioxide. Moreover, nano pulse electric discharge plasma was also formed in supercritical fluids; reaction of amino acid was also observed. Aiming at establishment of a new reaction field, we did fusion research of supercritical fluids and electric discharge plasma. In this experiment, argon at the pressurized state was used as a reaction medium. Initially, alanine aqueous solution of 0.1 mol/L was loaded to a plasma reactor (inner volume: 600 mL) and reached under the desired conditions (290-308 K and 1-10.8 MPa). They were then analyzed by high-performance liquid chromatography (HPLC) and matrix-assisted laser desorption time of flight mass spectroscopy (MALDI TOF-MS). The possibility of polymerization of alanine was realized from the compound after electric pulsed discharge plasma processing.

pulsed corona discharge plasma, non-thermal equilibrium plasma, oligopeptide, alanine, supercritical argon