Masahide Yasuda

By Masahide Yasuda, Keisuke Takeo, Tomoko Matsumoto, Tsutomu Shiragami, Kazuhiro Sugamoto, Yoh-ichi Matsushita and Yasuyuki Ishii

Part of the book: Sustainable Degradation of Lignocellulosic Biomass

By Masahide Yasuda

Bioethanol, biodiesel, and biogas have gained much attention as sustainable energy alternatives to petroleum‐based fuels. Bioethanol production is the most typical method to provide liquid fuel. Recently cellulosic materials have been recognized as one of the promising sources for bioethanol, since they are not directly in competition with food sources. However, ethanol concentration is usually too low to separate by distillation at a low‐energy cost. Gaseous H2 is spontaneously isolated without operation to separate. Therefore, H2 production is an economical approach to biofuels. Photocatalytic H2 production over a Pt‐loaded TiO2 is initiated by the charge separation. Electrons reduce water to generate H2, while holes oxidize hydroxide to hydroxyl radicals. Generally, the use of sacrificial agents remarkably accelerates the H2 production since the hydroxyl radical is consumed by them. This chapter deals with the photocatalytic H2 production (PR) using sacrificial water‐soluble materials derived from lignocelluloses, lipids, and Chlorella. Lignocellulosic Italian ryegrass (2.00 g) was turned into H2 (78.7 mg) through alkali treatment, hydrolysis, and PR processes. The PR process of glycerol (10.4 g) and methanol (11.3 g), which were by‐products in biodiesel synthesis, formed H2 (3.10 g). Dried Chlorella (10 g) was turned into H2 (578 mg) by protease hydrolysis and PR.

Part of the book: Frontiers in Bioenergy and Biofuels

By Masahide Yasuda and Jin Matsumoto

This chapter describes the photocatalysis action of (dihydroxo)tetraphenyl¬porphyrinato complexes of high valent P (V), Ge (IV), and Sb (V) (P(tpp), Ge(tpp), and Sb(tpp)). These chromophores were fixed onto silica gel (SiO2) through Coulombic forces and hydrogen bonding between axial hydroxo ligands and silanol groups to produce M(tpp)/SiO2 (M = P, Ge, and Sb) composites. M(tpp)/SiO2 were applied to the photo-inactivation of Escherichia coli and Legionella pneumophila. Moreover, M(tpp)/SiO2 was subjected to practical experiments for the photoinactivation of L. pneumophila naturally occurring in a cooling tower and a public fountain. It is noteworthy that 80 g of Sb(tpp)/SiO2 catalyst, containing 40 mg of Sb(tpp) maintained a concentration of Legionella species below 100 CFU/100 mL for 120 days in 13 m3 of water in a fountain under sunlight exposure. The photoinactivation proceeded through the liberation of M(tpp) from SiO2, adsorption of M(tpp) inside bacteria, and generation of reactive oxygen species, such as singlet oxygen, under visible light irradiation, thus resulting in bacteria apoptosis. Based on these results, we developed water-soluble porphyrins by modification of P and Sb porphyrin axial ligands to alkyloxo, alkylethylenedioxy, and alkylpyridinium groups. These water-soluble porphyrins were applied to the photodynamic inactivation of E. coli and Saccharomyces cerevisiae.

Part of the book: Visible-Light Photocatalysis of Carbon-Based Materials

By Jin Matsumoto, Tomoko Matsumoto, Kazuya Yasuda and Masahide Yasuda

The activity of singlet-oxygen sensitizers for photodynamic inactivation (PDI) of microorganisms and photodynamic therapy of tumor cells has been evaluated using Escherichia coli, Saccharomyces cerevisiae, and human cancer cell lines. In this chapter, drug resistance of E. coli was examined based on the PDI activity of a variety of RPy-P-porphyrin sensitizers with different number of ionic valence and different hydrophobic characters. The PDI activities toward E. coli were evaluated using the minimum effective concentrations ([P]) of the porphyrin sensitizers. It was found that the [P] value for E. coli was larger than that for S. cerevisiae. E. coli has drug-resistance toward hydrophobic and mono-cationic porphyrins. However, E. coli has weak drug-resistance toward the porphyrins with both polycationic character and hydrophobicity. Since the outer membrane mainly consists of lipopolysaccharides and phospholipids that are negatively charged, cationic porphyrins are able to adsorb to the outer leaflet. Then the cationic porphyrins with hydrophobic character can interact with not only the outer leaflet but also inner leaflet of the outer membrane and the plasma membrane. Thus, porphyrins may be incorporated inside E. coli cells via the self-promoted uptake pathway. Moreover, polycationic porphyrins can interact with DNA and proteins by strong binding affinities.

Part of the book: The Universe of Escherichia coli

By Masahide Yasuda, Tomoko Matsumoto and Toshiaki Yamashita

Biodiesel fuel (BDF) has gained much attention as a new sustainable energy alternative to petroleum-based fuels. BDF is produced by transesterification of vegetable oil or animal fats with methanol along with the co-production of glycerol. Indeed, transesterification of vegetable oil (136.5 g) with methanol (23.8 g) was performed under heating at 61°C for 2 h in the presence of NaOH (0.485 g) to produce methyl alkanoate (BDF) and glycerol in 83.7 and 73.3% yields, respectively. Although BDF was easily isolated by phase separation from the reaction mixture, glycerol and unreacted methanol remained as waste. In order to construct a clean BDF synthesis, the aqueous solution of glycerol and methanol was subjected to sacrificial H2 production over a Pt-loaded TiO2 catalyst under UV irradiation by high-pressure mercury lamp. H2 was produced in high yield. The combustion energy (ΔH) of the evolved H2 reached 100.7% of the total ΔH of glycerol and methanol. Thus, sacrificial agents such as glycerol and methanol with all of the carbon attached to oxygen atoms can continue to serve as an electron source until their sacrificial ability was exhausted. Sacrificial H2 production will provide a promising approach in the utilization of by-products derived from BDF synthesis.

Part of the book: Glycerine Production and Transformation