Effects of surface characteristics of activated carbon on the adsorption of 2-methylisobornel (MIB) and geosmin from natural water

Five powdered activated carbons (PACs), including one fruit-based, one wood-based, and three bituminous coal-based, were selected for the investigation of the effects of surface characteristics of activated carbon on the adsorption of 2-methylisobornel (MIB) and geosmin. Characterization of the carbons was performed using nitrogen adsorption, Fourier transform infra-red (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). All the carbons showed a broad absorption band in the 1300–1000 cm−1 region, which can be assigned to C–O stretching and O–H bending modes of alcoholic, phenolic, and carboxylic groups in FTIR spectra. The contents of O and C on the surfaces of carbons were acquired from the data of XPS analysis. Statistical analyses on the relationship between the adsorption capacities and different carbon surface parameters (O content, CO and C–O chemical group contents, the surface area, different pore volumes, iodine number and methylene blue number) were performed using Spearman rank correlation method. A good linear relationship between the adsorption capacities for MIB and geosmin and the micropore volumes was acquired. Both of iodine number and methylene blue number, the two most often used parameters for the evaluation of activated carbon quality, and other parameters, such as meso and total pore volumes, surface area, O and C–O contents were found to be insignificant in correlation with the adsorption capacities of MIB and geosmin. The volume of micropores could be used as an effective indicator for the selection of PAC for the removal of both MIB and geosmin.