The Effect of Coal Fly Ash Treatment with NaOH on the Characters and Adsorption Capacity toward Pb（Ⅱ） in the Solution

Coal fly ash （CFA） generated by coal-based thermal power plants is mainly composed of some oxides having high crystallinity, including quartz and mullite. In this study, the effect of CFA crystallinity toward its capacity on Pb（Ⅱ） adsorption was investigated. CFA with various crystaUinity was obtanied by refluxing it with sodium hydroxide （NaOH） solution having various concentrations （1-7 M） at various temperature and reflux time. To evaluate the effect of crystallinity of treated CFA on the adsorption capacity, adsorption of Pb（Ⅱ） solution with treated CFA was carried out. The research shows that the reflux of CFA with NaOH solution leads to the crystallinity of quartz and mullite in CFA decreased. The decrease is proportional with the concentration increasing, the temperature elevation, and the longer time. The reflux using NaOH solution with high concentration （〉 3 M） in addition causes a decrease in the crystallinity of quartz and mullite, also results in the formation of hydroxysodalite. The decrease of the CFA crystalllinity gives an increase in CFA adsorption capacity toward Pb（Ⅱ） solution.