Photocatalytic partial oxidation of methylpyridine isomers on TiO2 particles under an anaerobic condition

Photocatalytic oxidation of methylpyridine isomers (2-methylpyridine, 3-methylpyridine, and 4-methylpyridine) was investigated in a mixed solution of acetonitrile and water or acetonitrile using various kinds of TiO2 powders as photocatalysts. The main products from methylpyridine isomers were pyridinecarboxaldehyde isomers (2-pyridinecarboxaldehyde, 3-pyridinecarboxaldehyde, and 4-pyridinecarboxaldehyde). Rutile large TiO2 particles showed the highest level of activity for oxidation of 2-methylpyridine probably because band bending was necessary for the oxidation of 2-methylpyridine. On the other hand, a fine particle having an anatase or rutile phase showed a higher level of activity than large TiO2 particles for oxidation of 3-methylpyridine. A rutile fine particle showed the highest level of activity for the reaction. It was found that pure rutile or pure anatase particles were inactive for oxidation of 4-mathylpyridine. If the particles are not extremely small, pure rutile and pure anatase powders show fairly high levels of activity, and those containing both anatase and rutile phases show the highest level of activity. The activity of pure rutile particles was also enhanced by physically mixing them with a small amount of small anatase particles, which were inactive for this reaction. These results can be explained by the synergism between rutile and anatase particles. All of these reactions effectively proceeded even under anaerobic conditions. Photocatalytic reduction of methylpyridine isomers concomitantly proceeded on TiO2 particles under the conditions used. These results suggest that the activities of TiO2 photocatalysts for oxidation of methylpyridine isomers are dominated by the oxidation potential of alkylpiridine and band bending of TiO2 particles

Synthesis of nanosized TiO2 particles in reverse micelle systems and their photocatalytic activity for degradation of toluene in gas phase

Nanosized pure TiO2 particles with high crystallinity and large surface area were prepared by hydrolysis of tetrabutyl titanate in water/Triton X-100/isooctane reverse micelle solutions as reaction media followed by hydrothermal treatment to improve crystallinity. The prepared TiO2 nanoparticles were characterized by XRD, BET, TGA, FT-IR and TEM. The size of ultrafine particles was controlled by changing the water content of the reverse micelle solution. The TiO2 particles showed monodispersity, large surface area and high degrees of crystallinity and thermostability. The photocatalytic activity of the TiO2 particles was evaluated by decomposition of toluene in the gas phase. The activity of the TiO2 nanoparticles was higher than that of commercially available anatase fine particles, such as ST-01, which is one of the most active photocatalysts for degradation of organic compounds in the gas phase

Photocatalytic Activity of a TiO2 Photocatalyst Doped with C4+ and S4+ Ions Having a Rutile Phase Under Visible Light

C4+ and S4+-codoped titanium dioxide (TiO2) having a rutile phase was prepared. By doping C4+ and S4+ ions into a TiO2 lattice, the absorption edge of rutile TiO2 powder was largely shifted from 400 to 700 nm. 2-Methylpyridine and methyleneblue were photocatalytically oxidized at high efficiency on C4+ and S4+-doped TiO2 under visible light at a wavelength longer than 5 nm

Supporting Interaction Analysis for Collaborative Learning

ssion. The key to understanding CSCL lies in understanding the rich interaction between individuals. However, it is difficult for even human users to analyze them in order to clarify what types of collaboration have occurred in the session and what educational benefits have been expected for the members through the session. So, we propose an interaction analysis support system that helps users to abstract essence of interaction from raw protocol data, and to understand what types of collaboration have been occurred in the session, and then infers educational benefits expected to be gained by the members through the interaction process. We describe what interaction analysis is and why the interaction analysis is difficult for educational practitioners and CSCL designers, and propose an interaction analysis support system to reduce the difficulties, and interaction patterns that are core part of the system. The interaction patterns represent typical interaction processes, which are abst

Supporting Interaction Analysis for Collaborative Learning

Many of software designers of CSCL environment have been suffering from complex and subtle educational requirements offered by clients. One of major causes of the problem they face is the lack of shared understanding of collaborative learning. We do not know what design rationale of CSCL environment is and even do not have common vocabulary to describe what the collaborative learning is. In this research, we are aiming at supporting such complex instructional design (ID) process of CSCL environment. To fulfill the aim we have been constructing an ontology to represent CSCL session[1,2]. The ontology will work as both vocabulary to describe the session and design patterns referred to during the instructional design process. To represent learning scenarios using the ontology will facilitate users ' shared understandings and reuse the scenarios. It is useful to store and provide effective learning scenarios as design patterns. As the first step to fulfill our aim, we adopt learning theories as foundation to analyze, design, and develop the learning sessions. The design patterns inspired by the theories provide design rationale for CSCL design. Currently, laying the ontology and CSCL models formulated in terms of the ontology as basis, we have been conducting a project aiming at developing various kinds of ID suppor

An Interaction Analysis Support System for CSCL -- An Ontological Approach to . . .

We can observe various kinds of interaction among members of a learning group during collaborative learning session. It is difficult for even human users to analyze them in order to clarify what types of collaboration have occurred in the session and what educational benefits have been expected for the members through the session. So, we propose an interaction analysis support system that helps users to abstract essence of interaction from raw protocol data, and to understand what types of collaboration have been occurred in the session, and then infers educational benefits expected to be gained by the members through the interaction process

MODELING LEARNER-TO-LEARNER INTERACTION PROCESS IN COLLABORATIVE LEARNING An Ontological Approach to Interaction Analysis

Abstract: In this poster, we introduce an example of interaction patterns which are models of desired interaction process inspired with learning theories and vocabulary to represent the models. To evaluate collaborative learning session itself and/or educational benefits for learners, we should analyze interaction process, and capture what actually happens in the session. However, the interaction process is too complex to analyze for novice teachers or system designers. One of major causes of the difficulty is the lack of models and vocabulary to represent the process. So, we propose the vocabulary and the models of the interaction process described by the vocabulary. 1