ゼオライト高含有硬化体に及ぼすアルカリ濃度の影響

Abstract

The discharge amount of coal ash was around 10 million tons every year from pulverized coal-fired power plants in Japan, so some efficient usage of fly ash is needed. Alkali activated aluminosilicate material, i.e. fly ash, attracts attention as a new usage of fly ash. Authors reported that the hardened material made of fly ash and sodium hydroxide with curing under hydrothermal condition at 180℃ obtained high strength and high cation exchange ability against cesium. This paper discusses the influence of mixing ratio among fly ash, sodium hydroxide and water on physicochemical properties of hardened material. We mainly focused on optimal mixing ratio between fly ash and sodium hydroxide to obtain high cation exchange capacity, CEC, with high adsorption performance against cesium ion. Through the parametric experiments, it was found that there are optimal mixing ratio between fly ash and sodium hydroxide to obtain high strength with enough amount of composed zeolite, and characteristic tendency between CEC and adsorption performance against cesium. With the increase in dosage of sodium hydroxide, CEC increased with reduction of adsorption performance against cesium. When NaOH/FA and water/FA was 8.2mass% and 33.8mass% respectively (molarity of NaOH was 5.9mol/L), hardened zeolite had high strength (σc=52.1N/mm2, σb=10.3N/mm2), cation exchange capacity (CEC, 152cmol/kg) and adsorption ability of cecium (Kd=35.4L/g).