| The adsorption of perchloric ion(ClO-4) on granular activated carbon (GAC) was studied in aqueous solution through batch experiments. The effect of pH, initial ClO-4 concentration and co-existed anions on ClO-4 adsorbed by GAC, adsorption kinetics and isothermal models were studied. The results show that the adsorption capacity of ClO-4 on GAC decreases in the alkaline solution, and increases with the increasing initial concentration. The competitive adsorption exists between co-existed anions and ClO-4 on GAC and the order of competitive effect is SO２－4>NO-3>CO２－3>H2ＰO-4>BrO-3≈ Cl-. The adsorption process follows pseudo-second order kinetics. The existed pore diffusion probably is the main rate-controlling step of adsorption process. In addition, adsorption of ClO-4 on GAC fits the Langmuir, Freundlich and Tempkin isothermal models in the range of experimental concentration. The adsorption of ClO-4 on GAC is spontaneous and exothermic, and the increase of temperature decreases the adsorption capacity. The maximum adsorption capacity is 13.00, 11.21 and 8.04 mg·g-1 at the temperatures of 288, 298 and 308 K, respectively. Adsorption of ClO-4 on GAC is favorable, but the reaction conditions, such as temperature, pH and co-existed concentration, should be controlled to improve the adsorption efficiency. |
