Carbohydrate Conversion by Irradiation with a Carbon Dioxide Laser

Abstract

Four polysaccharides, cellulose, glucomannan, β-1,3-glucan and starch, were irradiated with a CO2 laser beam under a stream of nitrogen, and the chemical properties of the degraded products were characterized. In all cases, melted materials were formed by blasting with vaporized materials. The amounts of melted materials and vaporized materials varied greatly depending upon the energy density and duration of irradiation. Scanning electron microscopic observations indicated that the pyrolytic action of CO2 laser irradiation was strictly limited to the surface of the melted layer. The melted materials were mainly composed of a series of anhydro-oligosaccharides corresponding to the original polysaccharides, together with monomeric 1,6-anhydrosugars. The vaporized materials from cellulose were composed of volatile gases and an oily material rich in levoglucosan, and also contained anhydro-cello-oligosaccharides identical to those observed in the melted materials. The results of this study demonstrate that CO2 laser irradiation can be used as a practical carbohydrate conversion method, and opens a new field of carbohydrate technology in which anhydrosugars can be utilized as the raw material.