Relationships Between Adsorption Mechanisms and Pore Structure for Adsorption of Natural Organic Matter by Virgin and Reactivated Granular Activated Carbons During Water Treatment

Abstract

Abstract Temporal changes in the pore structure of granular activated carbons (GACs) were investigated for two reactivated and one virgin GAC during water treatment. One reactivated GAC had experienced five cycles of treatment and reactivation (5xReac), whereas the other had experienced twelve cycles (12xReac). For the virgin GAC that became loaded with natural organic matter (NOM), nearly all pore volume loss occurred in pores 40 A. For the 5xReac, the greatest loss of pore volume occurred in the 100–500 A pores. The 12xReac GAC experienced some loss of pore volume in the 100–500 A pores. For each GAC, NOM adsorption initially caused pore volume loss in pores that were only slightly wider than the NOM itself. Subsequent to this initial stage, NOM was mostly retained in the 20–40 A pores for the virgin GAC and in the 100–500 A pores for the 5xReac GAC. This was followed by gradual migration of the NOM into smaller pores. A lull in NOM loading revealed distinctions in ho...