Abstract
Much waste ash has been released due to the incineration of massive refuse from daily life. The waste ash causes enormous problems from the viewpoint of environmental protection. The amountof ash is expected to increase based on a serious increase in rubbish disposal, not only in Japan but also throughout the world. So far, little is known of a suitable treatment for waste ash. The development of a new technical method has been required for the treatment and/or recycling of waste ash. The ash is composed mainly of amorphous silica and alumina with some alkaline and alkaline earth-metal ions. We tried to treat the ash with an alkali solution in order to crystallize it. Namely, the waste ash was heated with a sodium hydroxide solution at about 90℃ for up to 90 h. The products of the heating reaction were analyzed by means of a X-ray diffraction method, infrared spectroscopy, thermal analysis and scanning electron microscopy. These instrumental analyses showed that the reaction could transform the ash into hydroxy sodalite, one of the zeolites, crystalline aluminosilicates. The amount of zeolite increased with prolongation of the reaction time, reaching a maximum at about 60 h. Zeolite has some useful properties and functions, such as adsorption, cation exchange and catalytic activities, and is utilized as a material in many fields of industry. For example, the material is used for soil amendment, removal of heavy metals from wastewater, deodorization and moisture desorption. Thus, the present result is promising in opening the way for the disposal of waste incineration ash through application as a recycling resource and to control pollution for environmental preservation.
