Estimating the effects of dispersed organic polymers on the sorption of contaminants by natural solids. I. A predictive thermodynamic humic substance organic solute interaction model

Chin, Yu Ping; Weber, Walter J.

doi:10.1021/es00066a008

Cited by 117 publications

(109 citation statements)

References 19 publications

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“…Flory and Hocker (1971) proposed an equation to compute the activity "a" of small solute molecules in a polymer: [3.14] where subscript 1 represents the solute phase, subscript 2 represents the polymer, φ i is volume fraction concentration, V i is molar volume, and χ is called the Flory interaction parameter. Flory-Huggins theory has been used to describe the thermodynamics of organic contaminants in a soil-water system (Chiou, 1983;Chin, 1989;Spurlock,1994) and it was always simplified as:…”

Section: Interaction Between Organic Contaminants and Soilmentioning

confidence: 99%

Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

Huang¹

2001

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Contamination of soils by toxic organic pollutants is an environmental concern. The insitu electrokinetic (EK) technology is an emerging process to remediate the contaminated soils. Since the electro-osmotic (EO) flow rate and sorption behaviors of pollutants are two critical factors of the process, this study focuses on understanding the partition of nonionic organic contaminants in soil-water system, mechanisms of the EO flow, and the transport of organic compounds under an externally applied electrostatic field. The target compounds include chlorinated organic compounds and polycyclic aromatic hydrocarbons (PAHs). In order to improve the treatment efficiency, surfactant and bio-surfactant were used. A thermodynamic concept, fugacity, was introduced to illustrate the interactions between organics and the soil. A semi-empirical equation was derived to describe the EO flow rate in unsaturated soils. Moverover, the diffusion-advection-sorption model was used to simulate the transport of nonionic organic contaminants in the presence of an electrostatic field.The sorption experiments were conducted with various initial solute concentrations and different soil to solution ratios. The selected chlorinated organics include tetrachloroethylene (PCE), trichloroethylene (TCE), carbon tetrachloride, and chloroform. Results show that Langnuir isotherm can be used to express the distribution behavior of these chlorinated organic compounds i n the soil-water system. In addition to the hydrophobicity (K ow ), the concentration of organic compound and soil to solution ratio can influence the distribution behavior also. In order to illustrate the effects of the organic concentration and soil to solution ratio, the activity coefficient was used.The activity coefficient, γ, a relative interaction based on chosen reference state, is a useful means to express the quantitative feature of the organic-soil interaction without detailed information of their interaction mechanisms. By comparing the activity coefficients, γ w and γ s (i.e., X s /X w ), one can illustrate the trend of organic distribution at the soil-water interfaces.The concentration effect can be explained by the changes in the adsorption of organic onto the soil surface. Based on the experimental results, when increasing the organic compound concentrations, the activity coefficient, γ w , can be considered as a constant and γ s increases due to the increase of interaction energy. The change of γ s makes the sorption isotherms of PCE, TCE, carbon tetrachloride, and chloroform non-linear. According to γ s , it can be seen that the sorption between these selceted chlorinated organics and the soil is exothermic.The effect of soil to solution ratio can be attributed to the presence of dissolved organic matter (DOM) in the liquid phase. DOM enhances the organic dissolution, which in turns increases the organic concentration, i.e., X w . Therefore, the partition coefficients of these chlorinated compounds, i.e., X s /X w , decrease with increasing the soil to solution ...

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Section: Interaction Between Organic Contaminants and Soilmentioning

confidence: 99%

Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

Huang¹

2001

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“…Probably because the larger the particle size, the higher the content of organic carbon [28,36,37] . DOI…”

Section: Adsorbent ( Carbon Chain Length Pore Size Oxygen Functional mentioning

confidence: 99%

Research of Adsorption on PCBs: Isotherm Modeling and Influencing Factors

et al. 2016

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Abstract. PCBs are a group of persistent organic pollutants (POPs) in the environment. Adsorption behavior of PCBs has obtained great attention affecting the degradation, mobility activities. In this paper, adsorption process was studied systematically to figure out the model of adsorption, adsorption mechanism and the influencing factors, which will provides the theoretical basis for further research.

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“…Assuming V 1 K V 2 [2,33] and 1 K 1 for dilute concentrations of sorbate in the polymer [19], Equation 6 reduces to…”

Section: Flory-huggins Polymer Solution Theorymentioning

confidence: 99%

“…This model appears to describe well the partitioning behavior of several HOCs based on sorption to one soil over a relatively wide range of concentrations (60-90% aqueous solubility), as well as evidence of no competition between sorbates in bisolute systems. Chin and Weber [33] utilized a more robust form of Flory-Huggins theory in deriving an expression for the observed binding of HOCs with Aldrich humic acid. In this version of the partitioning model, the Flory-Huggins interaction parameter was expanded to include both dispersive as well as polar components of the enthalpic contribution, thus allowing for specific molecular interactions between sorbate and a relatively polar polymer (humic acid).…”

Section: Application Of Polymer Sorption Theory To Natural Systemsmentioning

confidence: 99%

“…This model provides no further information to explain the mechanisms associated with observed anomalous or non-Fickian type diffusion characteristic of condensed, glassy organic matrices [22,45]. Hence, while the Chiou et al [2], Chin and Weber [33], and Spurlock and Biggar [7,8,19] partitioning models may be applicable to rubbery organic matrices, they do not appear to address well the peculiar behavior of highly microporous, glassy (condensed) matrices without further modification. Flory [20] notes that volume change (either positive or negative) upon mixing of small sorbate molecules with liquid-like (rubbery) polymers, is ''beyond reach of the foregoing polymer solution theory.''…”

Section: Concentration Dependence Ofmentioning

confidence: 99%

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

LeBoeuf

Weber

1999

Enviro Toxic and Chemistry

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Abstract-This evaluation of the polymer-based Flory-Huggins sorption theory has shown that the model predicts relatively concentration-independent values for rubbery matrices, concentration-dependent values for more glassy matrices, and highly concentration-dependent, largely negative interaction parameters for sorption of phenanthrene onto Green River kerogen, Ohio Shale II kerogen, Illinois No. 6 and Wyoming coals, and poly(phenyl methacrylate). These greatly negative enthalpic contributions to the interaction parameter are only to be expected where specific sorbate-sorbent interactions exist, such as in polar sorbatepolar sorbent systems. The failure of the nonlinear partitioning model is explained in terms of its inability to predict these increased interactions of sorbing solutes within microvoids present within glassy matrices. Calculations of sorbent solubility parameters through use of this model do, however, provide good agreement with literature solubility parameter values for specific sorbents; it may thus prove useful for partial characterization of sorbents for which solubility parameters are unknown.

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Estimating the effects of dispersed organic polymers on the sorption of contaminants by natural solids. I. A predictive thermodynamic humic substance organic solute interaction model

Cited by 117 publications

References 19 publications

Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

Research of Adsorption on PCBs: Isotherm Modeling and Influencing Factors

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

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