Abstract
Biomass activated carbons were activated and pyrolyzed at 300-800 degrees C under nitrogen circumstance (named as CAC300-CAC800). The physicochemical characteristics of CACs and mechanisms of perchlorate (ClO4-) adsorption on CACs were investigated. Compared to CAC300, CAC600-CAC800 had higher surface area, total prove volume, higher hydrophobic surface and an abundant of oxygen-containing groups (-COH and -COOH) which contributed to a higher ClO4- adsorption capacity. The pH value of solution significantly affected ClO4- adsorption and the maximum ClO4- adsorption capacity occurred at pH 2.0 (less than pH(IEP)), where surface charge was positive. Electrostatic attraction and hydrogen bonding to oxygen-containing groups on CACs were considered as the dominant force for ClO4- adsorption. With the pH increased, electrostatic attraction disappeared and surface oxygen-containing groups were gradually deprotonated, and the ClO4- adsorption amount was gradually decreased few until pH 12.0. The batch adsorption experiments of ClO4- showed that CAC600-CAC800 were effective adsorbents for the adsorption of ClO4-