| Abstract
| - Soot particles vary in pore structure, surface properties,and content of authigenic (native) extractable organicchemicals. To better understand the effects of these propertieson sorption, aqueous sorption isotherms for 14C-labeledphenanthrene and 1,2,4-trichlorobenzene were obtained forfour soots of varying properties: two diesel referencesoots, a hexane soot, and an ozonated hexane soot. Substantialisotherm nonlinearity was observed. In comparison todiesel soot SRM 2975, diesel soot SRM 1650b had a muchhigher content of extractable authigenic organic chemicals,showed less sorption of 14C-labeled sorbate at low relativeconcentrations (Ce/Sw), and showed higher sorption athigh Ce/Sw. In comparison to normal hexane soot, the ozonatedhexane soot had a higher surface O/C ratio and showedsubstantially less sorption at all concentrations studied. Thesorption differences were attributed to the noteddifferences in properties, and results were interpretedthrough a dual-mode sorption model that includedthe possibility of both surface adsorption (modeled usinga Polanyi-based approach) and simple phase partitioning(linear absorption). Generally, such modeling indicated thatoverall uptake at low concentrations in all four sootswas dominated by surface adsorption but that sorption athigher sorbate concentrations in SRM 1650b was heavilyinfluenced by linear absorption within the natively boundorganic phase.
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