INFLUENCE OF CHARACTERIZED NATURAL ORGANIC MATERIAL ON ACTIVATED CARBON ADSORPTION .2. EFFECT ON PORE VOLUME DISTRIBUTION AND ADSORPTION OF2-METHYLISOBORNEOL

The adsorption of four ultrafiltration fractions of natural organic ma terial (NOM) had a significant effect on the surface area and pore vol ume distributions of a coal-based activated carbon. This effect was de pendent on the size of the compounds; the smaller fraction had the gre atest effect on the micropore volume, and the larger fractions had a g reater effect on the mesopore volume. Only the mesopore volume of a wo od-based activated carbon was reduced by adsorption of the NOM fractio ns. The competitive adsorption between five NOM ultrafiltration fracti ons and 2-methylisoborneol (MIB) was greatest for the smallest fractio n (ultrafiltration molecular weight <500), as this fraction was the mo st similar in size to MIB and therefore provided direct competition fo r the same adsorption sites. The NOM in a natural water sample display ed the greatest competition with MIB, due to the presence of small com pounds that were lost during the concentration and desalting procedure s used to obtain the NOM fractions. The competition between MIB and th e largest ultrafiltration fraction was very small and could probably b e attributed to smaller compounds present in this fraction. (C) 1997 E lsevier Science Ltd.