Thermodynamic Study on the Adsorption of Nickel ion onto Activated Carbons

摘要

The adsorption isotherms and kinetics of nickel ion onto commercial activated carbons were determined and investigated under different temperature and initial pH in solution. The pore size distribution, specific surface area and functional groups of activated carbons were characterized by N_2 adsorption isotherms and Boehm titration. The results showed that the nickel ion adsorption property of activated carbon from precursors including anthracite, long flame coal, lignite and coconut were 4.9,3.4,4.1, 5.2mg/g, respectively. There was no obvious correlation with surface area, total volume or surface functional group value. The nickel ion adsorption isotherms and kinetics fitted the Langmuir isotherm and pseudo-second-order model very well. The adsorption was a spontaneous endothermic process, in which the adsorption took place primarily due to the ion-exchange action in low concentration of 50mg/L. On the other hand, the adsorption depended on the physical adsorption when the concentration≥100mg/L. The nickel ion adsorption capacity was highly affected by solution pH, and the optimum initial pH ranged was from 4 to 7.