Preparation of Alkali-treaded Fly Ash Adsorbent and Its Application for Cd2+ Removal from Aqueous Solution

The modified fly ash (MFA) was prepared by calcining raw coal fly (FA) ash with Na2CO3 at high temperature. The preparation conditions of MFA and Effects of important parameters such as contact time, adsorbate concentration, pH and temperature on the sorption were researched, respectively. MFA obtained at calcining temperature of 550 degrees C and FA/Na2CO3 mass ratio of 1:2 shows the effective removal for Cd2+ from aqueous solution, and the maximum removal was close to 100% with the adsorbent dosage of 10 g/L, initial Cd2+ concentration of 200 mg/L at 25 degrees C. The adsorption kinetics of Cd2+ on MFA followed the pseudo-second-order model well and adsorption processes might be mainly controlled by intra-particle diffusion. The sorption is favourable at high temperature and the adsorption apparent activation energy was 68.08 kJ/mol which indicates the chemical nature of the adsorption.