Characteristics of ground granular activated carbon for rapid small scale column tests

The rapid small scale column test (RSSCT) has become a popular method to characterize and size granulated activated carbon (GAC) for water treatment facilities. In the procedure the GAC is ground and a specific size fraction is used in the RSSCT. Since GAC is produced and activated using different processes from different starting materials (e.g. bituminous, lignite, wood etc) there exists the possibility for a variation in the sorptive capacity and surface reactivity through out the particle, such as a less activated inner core of the particle. This could lead to a biasing of experiment scale-up results since only a specific size fraction is used. This study was carried out to determine if there is any variation in the surface properties of the activated carbon through the various size fractions. Four activated carbons manufactured from different source carbons were studied. Gas adsorption tests were performed to determine the physical morphology such as surface area, micro and meso pore size, and pore-volume. Boehm’s titrations were performed to check the surface’s chemical properties. Mohs hardness test was performed on all bulk GACs and the ground fractions and Zeta-potential test was performed to characterize the surface charges. There were no apparent difference found in the size fraction based on the total surface area, pore size, cumulative pore volume on the various size fraction generated from grinding the activated carbons. There were no significant differences in the chemical nature of the surfaces between the various size fractions of GAC. Hardness test indicated no variations in the hardness between the bulk GAC, the ground fractions and the unground core. The Zeta-Potential showed the same trend as the ratio of acidic sites to basic sites from the Boehm method for the four activated carbons --Abstract, page iv