使用済みコンクリート型枠用合板からの高吸着性炭化物の製造

Abstract

A large quantity of waste plywood panel for concrete form has recently been generated with progress of construction industry and its effective utilization become a social urgent problem. In this study, the production of charcoal from the waste plywood form and its adsorption characteristics were investigated. The virgin plywood form and the raw plywood material were also examined for reference. The plywood samples was first pulverized as a chip and carbonized at 500-1, 000°C under nitrogen atmosphere using an electric furnace. The yield of the charcoal was slightly decreased with increasing carbonization temperature, being about 30% at 800°C in the same manner as ordinary charcoals. The specific surface area of the charcoal was increased remarkably at the temperature range over 800°C. X-ray diffraction analysis reveals that the partial graphitization proceeded at carbonization temperature range over 800°C, particularly in the case of the waste plywood form. In the experiments of adsorption in aqueous solutions, the charcoal from the waste plywood form was found to have 3-5 times activity in the adsorption of alkaline dye (methylene blue) and acidic dye (orange II) compared to that from the raw plywood material and about 15 times activity in the adsorption of bisphenol A which is one of endocrine disruptors. Chemical analysis shows that the content of metal ions such as Ca2+, Na+, K+, Al3+ and Total-Fe was considerably larger in the charcoal from the waste plywood form than in that from the virgin plywood form and the raw plywood material. Therefore, the partial graphitization of the charcoal assumed to be accelerated by the catalytic action of the metal ions derived from concrete, which leads to the remarkable increase in the hydrophobicity of the charcoal surface, viz, in the adsoptive activity for organic compounds. It was concluded that the charcoal with high adsoptive activity could be produced from the waste plywood form without any additional activation procedures.