LeBoeuf's Comment on “Evaluation of the Glassy/Rubbery Model for Soil Organic Matter”

LeBoeuf, Eugene J.

doi:10.1021/es9900353

Cited by 5 publications

(2 citation statements)

References 10 publications

(6 reference statements)

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“…Solutes would likely have different affinities to these regions and could possibly sorb there via a different mechanism. This description is consistent with the distributed reactivity model (DRM) proposed for the sorption of aqueous organics to soils and sediments (25)(26)(27)(28)(29)(30)(31)(32)(33)(34). The model assumes that multiple sorption mechanisms of different reactivities can operate in parallel with differences in the reactivity being due to inhomogeneities in natural organic matter resulting from their various geologic ages.…”

Section: Introductionsupporting

confidence: 86%

Dual Reactive Domain Model for Sorption of Aqueous Organics by Wood Fiber

Severtson

Banerjee²

2001

Journal of Colloid and Interface Science

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Section: Introductionsupporting

confidence: 86%

Dual Reactive Domain Model for Sorption of Aqueous Organics by Wood Fiber

Severtson

Banerjee²

2001

Journal of Colloid and Interface Science

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“…In the first paper in this series (25), a more refined view of NOM was developed to encompass the inherent heterogeneity of natural organic matter as one originating from a complex conglomeration of bits and pieces of degraded or partially degraded biopolymers that manifest themselves into mechanically different rubbery and glassy states. Sorption of HOCs from aqueous solution within these matrices has been characterized as both linear (e.g., refs 29-33) and nonlinear sorption processes (e.g., refs 12, 34-40), and the relative nonlinearity of the sorption isotherm has been attributed to the presence of more condensed, diagenetically altered, glasslike regions of NOM (12,25,(37)(38)(39)(40)(41)(42)(43)(44)(45) or similarly to microporous regions of carbonaceous (e.g., soot) materials in soils (46)(47)(48). In this section, we expand our database of observed nonlinear sorption in sorbents with known glass transition temperatures (Tg) in an effort to further establish the role of macromolecular mobility in influencing sorption isotherm linearity.…”

Section: Resultsmentioning

confidence: 99%

Macromolecular Characteristics of Natural Organic Matter. 2. Sorption and Desorption Behavior

LeBoeuf

Weber

2000

Environ. Sci. Technol.

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The effects of the relative macromolecular mobilities of natural organic matter (NOM) matrices on their sorption/ desorption behavior with respect to phenanthrene are described. Sorption isotherm characteristics are found to correspond directly to the relative dominance of glassy and rubbery states, with nonlinear sorption being linked to the dominance of glassy regions within the natural and synthetic macromolecules examined. The Dual Reactive Domain Model (DRDM) developed in earlier studies provides an effective tool for identifying specific adsorption and absorption contributions to overall isotherm patterns. The Hysteresis Index (H.I.), also developed in earlier studies, is useful for quantifying differences between the sorption and desorption isotherms for each macromolecular sorbent. Confirming earlier observations with soils and sediments, a trend of increasing H.I. with decreasing oxygen/ carbon (O/C) atomic ratio is generally observed for the NOMs investigated. Correlation of isotherm nonlinearity and H.I. with macromolecular mobility is hypothesized and tested, leading to a general conclusion that the extent of isotherm nonlinearity and the H.I. are related to increasing glass transition temperature (T g ) of the NOM. Macromolecular sorbents display little or no desorption hysteresis under experimental conditions at or very near their T g , while sorbents that are clearly in their glassy state under those conditions manifest significant desorption hysteresis. This may relate in part to the fact that the times required for attainment of true sorption and/or desorption equilibria vary with the mobility and flexibility of macromolecular sorbent matrices, attaining only over extremely long periods of solute migration into and out of the less flexible glassy states of such matrices.

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