A distributed reactivity model for sorption by soils and sediments. 2. Multicomponent systems and competitive effects

McGinley, Paul M.; Katz, Lynn E.; Weber, Walter J.

doi:10.1021/es00045a006

Cited by 162 publications

(181 citation statements)

References 21 publications

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“…Therefore, earlier investigations [10,11,[42][43][44][45] showed that sorption of hydrophobic organic contaminants (HOCs) by soils and sediments is dominated by partitioning into relatively homogeneous, lipophilic, gel-like humic matrices, which can be recognized as a partition or dissolution process and has the linear adsorption features. A number of more recent studies [12][13][14][15][46][47][48][49][50][51][52][53][54][55] , however, have indicated that such sorption often manifests substantial deviations from a linear partition model, provided that very low concentrations of HOCs are studied. In that case, a presumed adsorption process is often observed, as evidenced by the nonlinear, slow, hysteretic and competitive sorption behaviors.…”

Section: Resultsmentioning

confidence: 99%

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

Zhou

Lü

et al. 2006

SCI CHINA SER B

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Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 250 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indicative of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic substances in the sorption of environmental pollutants.Keywords: atomic force microscopy (AFM), dissolved humic substances, morphology, aggregation, adsorption.Humic substances (HS) are a category of naturally occurring, biogenic, heterogeneous organic materials found in or extracted from soils, sediments, and natural waters that can generally be characterized as being yellow-to-black in color, of highly variable relative molecular masses, and refractory [1,2] . Derived from a variety of organic precursors (plant biopolymers such as lignin etc.), plant residues and animal debris via both transformation and synthesis processes [3] under the profound geochemical alteration, including the microbiological and chemical degradation, sedimentation and diagenesis as well, humic substances com-AFM study on the adsorption and aggregation behavior of dissolved HS on mica 257 prise highly complex composites of partially or completely degraded biomolecules, carbohydrates, lipids, and proteins etc. However, they cannot be classified into any of the normal, easily defined categories of discrete materials such as proteins, polysaccharides, and polynucleotides. As the major organic constituents of soils, sediments and waters, humic substances are ubiquitous in all terrestrial and aquatic environments. They can form molecular aggregates, dispersed in different colloidal states in solutio...

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Section: Resultsmentioning

confidence: 99%

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

Zhou

Lü

et al. 2006

SCI CHINA SER B

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“…The final concentration of methanol was maintained less than 0.05% v/v so that it did not interfere with the sorption of pollutants. Such experimental methodology is a standard protocol used by many researchers (McGinley et al, 1993;Haderlein et al, 1996;Xia and Ball, 1999). In fact, Haderlein et al (1996) has reported that methanol or acetonitrile upto 1% v/v did not measurably affect sorption.…”

Section: Methodsmentioning

confidence: 99%

QSAR Models To Predict Effect of Ionic Strength on Sorption of Chlorinated Benzenes and Phenols at Sediment–Water Interface

Rao

Asolekar

2001

Water Research

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Abstract}It is hypothesised that the experimental sorption coefficient normalised to the organic carbon fraction of sediment (K exp oc ) for non-ionic, hydrophobic, organic pollutant depends upon the molecular properties as well as background ionic strength of the aquatic system. The utility of this concept has been demonstrated by incorporating ionic strength as a parameter in the three quantitative structure activity relationships (QSARs) namely octanol-water partitioning coefficient model (Kow model), the linear solvation energy model (LSE model), and molecular connectivity indices theory (MCI model). Four chlorinated benzenes and two chlorinated phenols were employed in the present study. Sorption experiments using sediment from the Patalganga River were conducted in laboratory (bottle point method) at different ionic strengths (viz. 0.01, 0.05, and 0.10 M). The K cal oc values predicted using Kow model incorporating ionic strength compare reasonably well with the K exp oc values (r 2 ¼ 0:60 and standard error of estimator i.e. SEE=0.35). The LSE model incorporating ionic strength too, was found to be equally good (r 2 ¼ 0:67, SEE=0.33). An attempt has also been made to validate the QSARs developed in the present study utilising the sorption parameters experimentally measured by Dewulf et al. (1996)

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“…For example, over a wide range of concentrations, nonlinear isotherms are observed for numerous apolar organic compounds Pignatello 1997, 1998;Xing 1998;Xing and Chen 1999;. In addition, competitive sorption between pairs of apolar solutes is reported (Xing and Pignatello 1997;McGinley et al 1993;Xia and Pignatello, submitted). Young and Weber (1995) also reported concentrationdependent enthalpy of sorption (i.e., sorption potential changes with concentration).…”

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confidence: 99%

Sorption of anthropogenic organic compounds by soil organic matter: a mechanistic consideration

Xing¹

2001

Can. J. Soil. Sci.

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Xing, B. 2001. Sorption of anthropogenic organic compounds by soil organic matter: a mechanistic consideration. Can. J. Soil Sci. 81: 317-323. Sorption experiments with apolar organic compounds (naphthalene and 1,2-dichorobenzene) were conducted to evaluate sorption mechanisms in soil organic matter (SOM). All isotherms were nonlinear and competition between solutes was observed. Nonlinearity and competition increased in an order of peat humic acid (HA) < peat < peat humin. Isotherms of Al-saturated HA (Al-HA) were more nonlinear than untreated HA and Ca-HA, and sorption/desorption hysteresis occurred only in Al-HA. These results are not consistent with partitioning theory or the presence of high-surface-area carbonaceous materials (HSACM) in soil. But the results are consistent with dual-mode sorption, where SOM is postulated to have both condensed (rigid) and expanded (flexible) domains, and adsorption takes place only in the condensed domains and partitioning in both domains. These non-ideal sorptive behaviors need to be incorporated into predictive models to more accurately describe the fate and transport of organics in soil and subsurface environments.Key words: sorption, organic compounds, organic matter, dual-mode, partition, mechanisms Xing, B. 2001. Mécanique de la sorption des composés organiques anthropiques par la matière organique du sol. Can. J. Soil Sci. 81: 317-323. L'auteur a effectué des expériences sur la sorption de composés organiques apolaires (naphtalène et 1,2-dichlorobenzène) en vue d'approfondir la mécanique de la sorption dans la matière organique du sol (MOS). Les isothermes ne sont pas linéaires et les solutés se font concurrence. La non-linéarité et la concurrence s'intensifient selon la séquence « acide humique (AH) de la tourbe < tourbe < humine de la tourbe ». Les isothermes de l'AH saturé de Al (AH-Al) sont moins linéaires que ceux de l'AH non traité et de l'AH-Ca. Par ailleurs, on n'observe l'hystérésis de la sorption/désorption qu'avec l'AH-Al. Ces résultats ne sont pas cohérents avec la théorie du partage ni avec la présence de matière carbonée près de la surface, dans le sol. Ils sont toutefois cohérents avec la théorie de la sorption bimodale, qui repose sur le postulat que la MOS possède à la fois des domaines condensés (rigides) et expansés (souples), et que l'adsorption ne survient que dans les domaines condensés, alors qu'il y a partage dans les domaines des deux types. Il convient d'intégrer ces comportements non idéaux de la sorption aux modèles de prévision afin de mieux décrire le devenir et le transport de la matière organique dans le sol et le sous-sol.

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A distributed reactivity model for sorption by soils and sediments. 2. Multicomponent systems and competitive effects

Cited by 162 publications

References 21 publications

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

QSAR Models To Predict Effect of Ionic Strength on Sorption of Chlorinated Benzenes and Phenols at Sediment–Water Interface

Sorption of anthropogenic organic compounds by soil organic matter: a mechanistic consideration

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