Osamu Terakado

Thermal Decomposition of Printed Circuit Board in the Presence of Zinc Oxide under Inert and Oxidative Atmosphere: Emission Behavior of Inorganic Brominated Compounds

Thermal degradation of a FR-4 type printed circuit board, PCB, containing brominated flame retardant has been studied both in inert and oxidative atmosphere for the emission control of harmful brominated compounds. The presence of oxygen in atmosphere resulted in the reduction of the yield of hydrogen bromide, one of the major brominated compounds in thermal treatment, and in the enhancement of the formation of bromine and hypobromous acid. The intentional addition of zinc oxide to the PCB powder sample gave rise to the fixation of Br as zinc bromide. It also resulted in the promotion of the release of brominated compounds in comparison to the case of pure PCB. Thus, the addition of the oxide can be a benefit with respect to the bromine fixation and the kinetics of thermal treatment of PCB as well as metal recovery.

Formation of Carbonaceous Materials by Ultrasonic Atomization of Aqueous Ethanol Solution and Pyrolysis Treatment

The ultrasonic atomization of aqueous ethanol solution and the consequent pyrolysis treatment has been employed in order to explore a new technique for preparation of carbonaceous compounds. The deposition of fibrous carbon on titanium catalyst has been observed after 5 hours of treatment at pyrolysis temperature of 973–1173 K. The yield in carbon has increased in comparison to the control experiment without ultrasonic atomization. A TEM analysis has shown that the fibre has the diameter of 30 nm and the fibre growth occurs from the catalyst particles.

Production of Silicon-based Nano-scale Materials Through High Temperature Reduction of Silica by Titanium

The reduction of silica by titanium at 2073 K has been studied in order to develop a production process of silicon-based nano-scale materials. The silicon monoxide vapour, reaction intermediate products, has been transferred by argon carrier gas to colder parts of the reactor, which results in the disproportionation reaction to form Si and SiO2. The products include particles with diameter of 10–100 nm order and wires. An attempt to remove SiO2 by hydrofluoric acid treatment of the reduction products resulted in the enrichment of Si particles.

Synergetic Effect of Ultrasound Irradiation in the COD Removal and Degradation of L-Ascorbic Acid in Aqueous Solution by Aerobic Treatment

The ultrasound irradiation and simultaneous oxygen bubbling into the L-ascorbic acid aqueous solution has been studied in order to establish a cost-effective oxidation process for wastewater treatment. The application of ultrasound considerably increases the decomposition rate, while the relative chemical oxygen demand (COD) value is essentially unchanged. The influence of various process parameters, such as temperature and oxygen flow rate, has been studied. Moreover, we have carried out preliminary experiments on the influence of the addition of metal oxide particles, i.e. SiO2 and TiO2. The effects of particles on the degradation of AH2 and the COD compounds are discussed.