The Preparation And Modification Of Activated Carbons Separated From The Fly Ash

The reuse of fly ash produced from iron and steel manufacturing is an important issue due to the environmental concern. In this thesis, a new method of physical activation to prepare granular activated carbons (GACs) from the fly ash was developed. Modification techniques and their effects on the properties of the GACs were discussed.The coal tar was chosen as the binder and KOH was added in the carbon powder before carbonization and steam activation. The rotational tube furnace was used for the purpose of industrial applications. In order to increase the adsorptive selectivity, the GACs were modified by using oxidization (nitric acid, anodic oxidization etc.) or deoxidization (nitrogen, hydrogen etc.) methods. The surface appearance and the chemical property of the GACs were analyzed by SEM, XPS, FTIR and TG. The adsorption properties for volatile organic compounds and heavy metal ions Cr(VI) were investigated.The result showed that the KOH additive affected the microstructure, the pores distribution and the surface appearance of the GACs. When the KOH content reached 1.5%, the activated carbon with low ash content had the highest iodine adsorption value and specific surface area. Compared with the box furnace, the output of the GACs was improved; the activation was even and sufficient. After modification, the amount of oxygen group was changed which modified the chemical property of the GACs. Reducing the surface oxygen functionalities was in favor of adsorption of non-polar gas while increasing the surface acid oxygen functionalities is in favor of adsorption of polar gas. The adsorptive capacity of GACs to Cr(VI) can be increased by means of increasing the amount of surface oxygen functionalities and ion exchange capacity after HNO3 oxidization or anodic surface treatment.The item of"Preparation activated carbons from fly ash"will have good prospect through the inveatment and profit analysis.