Yuichi Kobayashi

Biodegradation of β-1,4-linked polyglucuronic acid (cellouronic acid)

Biodegradability of β-1,4-linked polyglucuronic acid (cellouronicacid), which was prepared from regenerated cellulose by2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation underaqueous conditions, was examined by enzymatic treatments and incubationtreatments with microorganisms collected from some soil samples. Degradation ofcellouronic acid was traced by size exclusion chromatography (HPSEC) or totalorganic carbon (TOC) of the treated products or solutions, respectively.Cellouronic acid was depolymerized by a commercial crude cellulase anddecreasedin its weight average degree of polymerization from about 1600 to 40 by thecellulase treatment at 20 °C for 40 days. 13C-NMRanalysis and liquid chromatography of the treated products showed thathydrolysis-type enzymes present in the crude cellulase as contaminantsprimarilydepolymerized cellouronic acid to give glucuronic acid. When aqueous solutionscontaining cellouronic acid were incubated with soil microorganisms for morethan 3 days, the TOC values decreased to less than 20% of the initial value,depending on molecular weight of the cellouronic acid used. The decreasing rateof TOC for cellouronic acid was clearly higher than that ofcarboxymethylcellulose, which is one of the cellulose derivatives havingcarboxymethyl substituents. These results imply that cellouronic acid has bothbiodegradability and metabolizability in the natural environment.

The Non-glycerol Process of Biodiesel Fuel Treated in Supercritical Methanol

Biodiesel fuel is a renewable fuel for diesel engine consisting of fatty acid methyl ester from organic oils and fats. In the conventional processes for production biodiesel fuel, glycerol is generally produced as a by-product. But, utilization of this by-product for other application is very hard, since various impurities are mixed. Therefore, we developed new process that does not generate glycerol. This process is simultaneous process of non-catalytic transesterification and thermal decomposition as treated in supercritical methanol. The product treated with 450°C in reaction temperature, 40MPa in pressure and 4 minutes in time is almost same properties with traditional biodiesel fuel.

Thermochemical Transformation of Biomass

The generation of energy from biomass is promoted as a measure to combat global warming. There are five main methods for processing biomass: combustion (including for the generation of electricity), carbonization, gasification (again including for the generation of electricity), gasification for methanol synthesis, and ethanol fermentation. Although agricultural biomass is abundant, it is thinly distributed over a wide area, so its practical use requires much time and effort for harvest, preparation, and storage. In particular, because agricultural biomass initially has high water content, it must be dried before it can be used. In addition, biomass frequently contains chlorinated compounds, which generate dioxins at low temperatures, and alkali metals and silicic acid, which melt at high temperatures during combustion. Therefore, the thermochemical transformation of agricultural biomass requires ingenuity to overcome these concerns. This is why the use of agricultural biomass for energy is not popular at the present time. However, increasing demand for structural innovation through energy policies due to rising fuel costs and global warming has stimulated the development of new technologies to use agricultural biomass as an energy source for achieving sustainable management of global energy sources and alleviating emissions of greenhouse gases.