Adsorption of copper ions on porous ceramsite prepared by diatomite and tungsten residue
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China)
Abstract: In order to realize resource utilization of industrial tungsten residue and treatment of heavy metal wastewater in mining and metallurgical area of south China, a novel ceramsite was prepared with the main raw materials of diatomite and tungsten residue. The adsorption behavior of copper ions in solution on the ceramsite was investigated. Results indicated that the surface of the newly-developed ceramsite was rough and porous. There were lots of pores across the ceramsite from inner to outside. MnFe2O4 was one of the main components of the ceramsite. The Cu2+ adsorption capacity by the ceramsite reached 9.421 mg/g with copper removal efficiency of 94.21% at 303 K, initial Cu2+ concentration of 100 mg/L and dosage of 0.5 g after 300 min adsorption. With increase of ceramsite dosage, the total adsorption amount of Cu2+ increased, but the adsorption capacity decreased. The adsorption capacity increased with the increase of solution pH. The isothermal adsorption of Cu2+ by the ceramsite fitted the Freundlich model better. The adsorption mainly occurred on a heterogeneous surface, and was a favorable process. The adsorption process closely followed the pseudo-second kinetic equation. In initial stage of wastewater treatment, the adsorption process should be controlled mainly by diffusion, and the removal of Cu2+ can be improved by enhancing agitation.
Key words: tungsten residue; ceramsite; heavy metal wastewater; Cu2+; adsorption