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

Abstract

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.

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

“…The Phen sorption on the LG fractions did not exhibit strong nonlinearity, due in part to its aliphatic component. In contrast, nonlinear sorption (n = 0.80, 0.63) by an extracted lignin and a degraded lignin had been found in other studies (Chefetz et al, 2000;LeBoeuf and Weber, 2000). The variation in the nonlinearity of Phen sorption by lignin could be due in part to the different lignin sources, extraction methods, and sorption experiment approaches.…”

Reevaluation of general partitioning model for sorption of hydrophobic organic contaminants by soil and sediment organic matter

“…h [48]. i [25]. j Argonne Premium Coal Program, Argonne, IL, USA k Approximate, from Lucht et al [26].…”

“…First, the models are unable to predict nonlinear sorption behavior for HOC-SOM-based sorption where specific interactions between the sorbate and sorbent are not expected (i.e., beyond simple van der Waals or possible dipole-induced dipole interactions) [5,9,25]. Spurlock and Biggar [7,8] only provide evidence of the nonlinear behavior of ureas on humic acid, where dipole-dipole or greater interactions may occur, and nonlinear sorption may be expected, as noted by a number of studies of herbicides on soils [42,43].…”

Binding of pyrene to fulvic acid fractions isolated by polarity‐based sequential elution

“…The study of the binding of pyrene to organic matters has revealed correlations between binding capacities, the concentrations of humic substances, specific organic matter structures, categories of organic matters, and pH [3][4][5][6][7]. The sorption capacity of pyrene to HAs and FAs differed by more than one order of magnitude.…”