title: The influence of the rigidity of geosorbent organic matter on non-ideal sorption behaviors of chlorinated benzenes.
abstract: This study focused on evaluating the influence of the rigidity of natural organic matter (NOM) associated with four natural geosorbents in controlling the non-ideal sorption behaviors of five chlorinated benzenes. Single solute sorption isotherms for each sorbate/sorbent combination were modeled and interpreted by the Freundlich sorption isotherm and the adsorption-partitioning model based on Polanyi-Manes theory (PM model). "Rigid" organic matter was operationally quantified as the fraction of carbon resistant to wet chemical oxidation (hard carbon) or thermal oxidation (soot carbon); atomic H/O ratios indicated a close correlation between the degree of reduction of the NOM and its rigidity. Sorbents with larger rigid carbon fractions had more non-linear sorption isotherms and higher organic carbon (OC) normalized sorption affinities. The size of the PM hole filling domain for a given sorbent was closely correlated with the extent to which the sorbent's affinity for chlorobenzenes exceeded predictions from a linear free energy relationship. Loss of some portions of the rigid character of the NOM domain due to the penetration of sorbate molecules (plasticization) was discussed as a possible contributor to the non-ideal sorption behaviors observed in this study. The existence of a permanently rigid NOM domain, not subject to plasticization under environmental conditions, was postulated as an additional factor determining the observed sorption behavior.
authors.affiliation: Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, CA 95616, USA.
authors.forename: Daeyoung
authors.initials: D
authors.lastname: Ju
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Young
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry; D002722:Chlorobenzenes / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D012995:Solubility; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002722:Chlorobenzenes; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D002244:Carbon