Sorption of Organic Contaminants - Revision history

Admin at 20:58, 11 February 2026

2026-02-11T20:58:18Z

Admin at 19:51, 3 February 2025

2025-02-03T19:51:13Z

Admin at 21:45, 26 April 2022

2022-04-26T21:45:02Z

Jhurley at 20:36, 4 October 2020

2020-10-04T20:36:08Z

Admin at 18:33, 24 September 2020

2020-09-24T18:33:55Z

Jhurley: /* Measuring Sorption */

2019-05-16T16:07:09Z

‎Measuring Sorption

Jhurley: /* Measuring Sorption */

2019-05-16T16:06:15Z

‎Measuring Sorption

Jhurley: /* Summary */

2019-05-16T16:04:25Z

‎Summary

Jhurley: /* Impact on Groundwater Transport */

2019-05-16T16:02:56Z

‎Impact on Groundwater Transport

Jhurley at 15:53, 16 May 2019

2019-05-16T15:53:37Z

@@ Line 7: / Line 7: @@
 *[[Chlorinated Solvents]]
 *[[Petroleum Hydrocarbons (PHCs)]]
 '''Contributor(s):''' [[Richelle Allen-King|Dr. Richelle Allen-King]]
 '''Key Resource(s)''':

@@ Line 14: / Line 14: @@
 '''Key Resource(s)''':
-*[//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Basic Concepts of Contaminant Sorption at Hazardous Waste Sites]<ref>Piwoni, M.D. and Keeley, J.W., 1990. Basic concepts of contaminant sorption at hazardous waste sites. Ground-Water Issue; EPA-540/4-90/053. [//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Report.pdf]</ref>
+*[//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Basic Concepts of Contaminant Sorption at Hazardous Waste Sites]<ref>Piwoni, M.D. and Keeley, J.W., 1990. Basic concepts of contaminant sorption at hazardous waste sites. Ground-Water Issue; EPA-540/4-90/053. [//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Report pdf]</ref>
 ==Introduction==

@@ Line 8: / Line 8: @@
 *[[Petroleum Hydrocarbons (PHCs)]]
-'''CONTRIBUTOR(S):''' [[Richelle Allen-King|Dr. Richelle Allen-King]]
 '''Key Resource(s)''':

@@ Line 6: / Line 6: @@
 *[[Chlorinated Solvents]]
-*[[Petroleum Hydrocarbons]]
+*[[Petroleum Hydrocarbons (PHCs)]]
 '''CONTRIBUTOR(S):''' [[Richelle Allen-King|Dr. Richelle Allen-King]]

@@ Line 8: / Line 8: @@
 *[[Petroleum Hydrocarbons]]
-'''CONTRIBUTOR(S):''' [[Richelle Allen-King]]
+'''CONTRIBUTOR(S):''' [[Richelle Allen-King|Dr. Richelle Allen-King]]
 '''Key Resource(s)''':
-*[//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf  Basic Concepts of Contaminant Sorption at Hazardous Waste Sites]<ref>Piwoni, M.D. and Keeley, J.W., 1990. Basic concepts of contaminant sorption at hazardous waste sites. Ground-Water Issue; EPA-540/4-90/053. [//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf  Report.pdf]</ref>
+*[//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Basic Concepts of Contaminant Sorption at Hazardous Waste Sites]<ref>Piwoni, M.D. and Keeley, J.W., 1990. Basic concepts of contaminant sorption at hazardous waste sites. Ground-Water Issue; EPA-540/4-90/053. [//www.enviro.wiki/images/e/e8/1990-Piwoni-Basic_concepts_sorption_haz_site_EPA_540-4-90-053.pdf Report.pdf]</ref>
 ==Introduction==

@@ Line 29: / Line 29: @@
 In some cases, the experimental data show an approximately linear relationship between aqueous and sorbed concentration, and the experimental results can be summarized in the form of a partition or distribution coefficient, ''K<sub>d</sub>'': <br>
-[[File:Allen-King1w2 Eq1.png|center|300 px]]
+[[File:Allen-King1w2 Eq1.png|center|320 px]]
 where ''C<sub>S</sub>'' is the solid (sorbed) concentration and ''C<sub>w<sub>'' is the aqueous (dissolved) concentration.  By convention, ''C<sub>s</sub>'' has units of µg/g and ''C<sub>s</sub>'' has units of µg/mL, so ''K<sub>d</sub>'' has units of mL/g.

@@ Line 29: / Line 29: @@
 In some cases, the experimental data show an approximately linear relationship between aqueous and sorbed concentration, and the experimental results can be summarized in the form of a partition or distribution coefficient, ''K<sub>d</sub>'': <br>
-[[File:Allen-King1w2 Eq1.png|center|400 px]]
+[[File:Allen-King1w2 Eq1.png|center|300 px]]
 where ''C<sub>S</sub>'' is the solid (sorbed) concentration and ''C<sub>w<sub>'' is the aqueous (dissolved) concentration.  By convention, ''C<sub>s</sub>'' has units of µg/g and ''C<sub>s</sub>'' has units of µg/mL, so ''K<sub>d</sub>'' has units of mL/g.
 When the relationship between ''C<sub>s</sub>'' and ''C<sub>w</sub>'' is non-linear, the experimental data are commonly represented by the Freundlich isotherm equation:<br>
-[[File:Allen-King1w2 Eq2.png|center|400px]]
+[[File:Allen-King1w2 Eq2.png|center|340px]]
 where ''K<sub>F</sub>'' and ''n'' are empirically estimated coefficients specific to the sorbate, sorbent and equation used.
 In most cases, ''absorption'' processes follow a linear isotherm.  However, ''adsorption'' processes often follow a nonlinear relationship between the sorbed and dissolved contaminant concentrations.  When both absorption and adsorption occur, a non-linear relationship is used to represent the sorption results.
 ==Impact on Groundwater Transport==

@@ Line 85: / Line 85: @@
 ==Summary==
 Nonionic and nonpolar organic contaminants including chlorinated solvents and petroleum hydrocarbons can become associated with solid phase organic matter in the soil, sediment, and rock.  When amorphous organic matter is the primary sorbent, sorption is linear and distribution coefficients can be estimated from empirical correlations with contaminant properties (aqueous solubility or octanol-water partition coefficient) and site-specific measurements of solid phase organic carbon.  However, when thermally altered carbonaceous materials (TACMs) are present, sorption may be non-linear and the empirical correlations may substantially underestimate sorption at low contaminant concentrations.
 ==References==

@@ Line 47: / Line 47: @@
 The average rate that a contaminant migrates in groundwater is reduced because the sorbed portion of the contaminant does not migrate.  The impact of sorption on the average contaminant transport velocity can be estimated using a Retardation Factor (''R''):
-[[File:Allen-King1w2 Eq3.png|center|600 px]]<br />
+[[File:Allen-King1w2 Eq3.png|center|620 px]]
 [[File:Allen-King1w2 Fig3.png|thumb|400 px|Figure 3. Linear correlation between organic carbon content (''f<sub>oc</sub>'') and sorption distribution coefficient (''K<sub>d</sub>'') for four chlorinated aromatic contaminants<ref name="Schwarzenbach1981" />. ]]
@@ Line 53: / Line 53: @@
 When sorption of the contaminant is described by a linear isotherm and sorption processes are fast relative to water flow, ''R'' can be estimated as:
-[[File:Allen-King1w2 Eq4.png|center|450 px]]
+[[File:Allen-King1w2 Eq4.png|center|440 px]]
 where ''&rho;<sub>b</sub>'' is the bulk density of the solid phase and ''&theta;<sub>w</sub>'' is the water filled porosity.  When sorption is non-linear and is described with the Freundlich isotherm equation, ''R'' can be estimated as:

@@ Line 15: / Line 15: @@
 ==Introduction==
-Sorption is a non-mechanistic term that describes uptake of a contaminant by a solid phase sorbent (soil, sediment, rock or an engineered material such as [https://en.wikipedia.org/wiki/Activated_carbon activated carbon]).  This article focuses on sorption of nonionic and nonpolar organic contaminants and their associations with subsurface materials.  For these contaminants, sorption is almost exclusively associated with organic matter in the solids and is a reversible process. Sorption of ionic and polar organic contaminants is not described in this article.
+Sorption is a non-mechanistic term that describes uptake of a contaminant by a solid phase sorbent (soil, sediment, rock or an engineered material such as [[wikipedia: Activated carbon | activated carbon]]).  This article focuses on sorption of nonionic and nonpolar organic contaminants and their associations with subsurface materials.  For these contaminants, sorption is almost exclusively associated with organic matter in the solids and is a reversible process. Sorption of ionic and polar organic contaminants is not described in this article.
-In this article, the term ‘sorption’ includes all processes that cause the dissolved organic compound (sorbate) to become associated with the solid phase (sorbent). For nonpolar organic compounds, sorption occurs by either adsorption or absorption. [https://en.wikipedia.org/wiki/Absorption_(chemistry) Absorption] is a volume-based process whereby the sorbate diffuses into the organic matter, analogous to the way that organic contaminants partition between immiscible oil and aqueous phases. In contrast, [https://en.wikipedia.org/wiki/Adsorption adsorption] describes the interaction between the contaminant and the sorbent surfaces.
+[[File:Allen-King1w2 Fig1a.png|right|thumb| 400 px|Figure 1a. Batch reactor experiments to generate points on a sorption isotherm (Figure 1b). This Figure shows two samples prepared in duplicate with soil-free control vials and vials to verify the contaminant mass added to the systems<ref name="Chiou1983">Chiou, C.T., Porter, P.E. and Schmedding, D.W., 1983. Partition equilibriums of nonionic organic compounds between soil organic matter and water. Environmental Science & Technology, 17(4), pp.227-231. [http://dx.doi.org/10.1021/es00110a009 doi: 10.1021/es00110a009]</ref>.]]
 ==Measuring Sorption==
-[[File:Allen-King1w2 Fig1a.png|right|thumb| 400 px|Figure 1a. Batch reactor experiments to generate points on a sorption isotherm (Fig. 1b). This Figure shows two samples prepared in duplicate with soil-free control vials and vials to verify the contaminant mass added to the systems<ref name="Chiou1983">Chiou, C.T., Porter, P.E. and Schmedding, D.W., 1983. Partition equilibriums of nonionic organic compounds between soil organic matter and water. Environmental Science & Technology, 17(4), pp.227-231. [http://dx.doi.org/10.1021/es00110a009 doi: 10.1021/es00110a009]</ref>.]][[File:Allen-King1w2 Fig1b.png|thumb|400 px|Figure 1b. Linear isotherms for eight compounds in one soil<ref name="Chiou1983" />. ]]
+[[File:Allen-King1w2 Fig1b.png|thumb|400 px|Figure 1b. Linear isotherms for eight compounds in one soil<ref name="Chiou1983" />. ]]
 Sorption can be measured in the laboratory by placing a known mass of the contaminant, water, and uncontaminated sediment in a batch reactor (Figure 1a). The system is mixed for a specific duration (contact time) and then the aqueous and sorbed contaminant concentrations are determined. This process is repeated, adding a range of different initial contaminant masses to achieve a range of aqueous contaminant concentrations. When the experiment is run at constant temperature until the concentrations in the solid and liquid phases approach equilibrium, the resulting data plot is termed an isotherm. Figure 1b shows linear sorption isotherms for eight compounds measured in one soil.
@@ Line 41: / Line 42: @@
 ==Impact on Groundwater Transport==
 Sorption reduces the amount of contaminant in the aqueous phase, slowing contaminant migration. Sorbed contaminants are also less available for biological or chemical degradation reactions, which will reduce the effectiveness of many remedial technologies.
 The average rate that a contaminant migrates in groundwater is reduced because the sorbed portion of the contaminant does not migrate.  The impact of sorption on the average contaminant transport velocity can be estimated using a Retardation Factor (''R''):
-[[File:Allen-King1w2 Eq3.png|center|600 px]]
+[[File:Allen-King1w2 Eq3.png|center|600 px]]<br />
-[[File:Allen-King1w2 Fig3.png|thumb|400 px|Figure 3. Linear correlation between organic carbon content (''f<sub>oc</sub>'') and sorption distribution coefficient (<sub>Kd</sub>) for four chlorinated aromatic contaminants<ref name="Schwarzenbach1981" />. ]]
+[[File:Allen-King1w2 Fig3.png|thumb|400 px|Figure 3. Linear correlation between organic carbon content (''f<sub>oc</sub>'') and sorption distribution coefficient (''K<sub>d</sub>'') for four chlorinated aromatic contaminants<ref name="Schwarzenbach1981" />. ]]
 When sorption of the contaminant is described by a linear isotherm and sorption processes are fast relative to water flow, ''R'' can be estimated as:
-[[File:Allen-King1w2 Eq4.png|center|400 px]]
+[[File:Allen-King1w2 Eq4.png|center|450 px]]
 where ''&rho;<sub>b</sub>'' is the bulk density of the solid phase and ''&theta;<sub>w</sub>'' is the water filled porosity.  When sorption is non-linear and is described with the Freundlich isotherm equation, ''R'' can be estimated as:
-[[File:Allen-King1w2 Eq5.png|center|400px]]Figure 2 illustrates the effect of ''C<sub>w</sub>'' on ''R'' when 1/''n'' is less than 1 and  ''&rho;<sub>b</sub>'' = 1.5 g/cm<sup>3</sup>'',  &theta;<sub>w</sub> = ''0.3 mL/cm<sup>3</sup>and ''K<sub>F</sub> = 2.''  When 1''/n'' is less than 1, sorption has limited effect in slowing the migration of a high concentration plume (''C<sub>w</sub>'' > 10 mg/L).  However, as the aquifer is remediated and contaminant concentrations drop below 0.1 mg/L, non-linear sorption has a much more pronounced impact, slowing aquifer cleanup.
+[[File:Allen-King1w2 Eq5.png|center|400px]]
 ==''K<sub>d</sub>'' Estimation Methods==
@@ Line 66: / Line 68: @@
 where ''f<sub>oc</sub>'' is the fractional organic carbon content of the soil, sediment or rock. This approach empirically separates variations in ''K<sub>d</sub>'' according to variations in the organic matter concentration, an important property of the sorbent, and the ''K<sub>oc</sub>'', which is intended to capture differences in the chemical properties of the contaminant.
-Experimental investigations (summarized in Allen-King et al., 2002<ref name="Allenking2002">Allen-King, R.M., Grathwohl, P. and Ball, W.P., 2002. New modeling paradigms for the sorption of hydrophobic organic chemicals to heterogeneous carbonaceous matter in soils, sediments, and rocks. Advances in Water Resources, 25(8), pp.985-1016. [http://dx.doi.org/10.1016/S0309-1708(02)00045-3 doi: 10.1016/S0309-1708(02)00045-3]</ref>) with a variety of sorbents and contaminants has shown that ''K<sub>oc</sub>'' values are correlated with contaminant hydrophobicity. This allows ''K<sub>oc</sub>'' to be estimated using empirical correlations with the contaminant aqueous solubility or [https://en.wikipedia.org/wiki/Partition_coefficient octanol-water partition coefficient] (''K<sub>ow</sub>'') (Figure 4).  Using this approach, ''K<sub>d</sub>'' can be estimated using site specific measurements of ''f<sub>oc</sub>'' and literature values of contaminant properties.
+Experimental investigations (summarized in Allen-King et al., 2002<ref name="Allenking2002">Allen-King, R.M., Grathwohl, P. and Ball, W.P., 2002. New modeling paradigms for the sorption of hydrophobic organic chemicals to heterogeneous carbonaceous matter in soils, sediments, and rocks. Advances in Water Resources, 25(8), pp.985-1016. [http://dx.doi.org/10.1016/S0309-1708(02)00045-3 doi: 10.1016/S0309-1708(02)00045-3]</ref>) with a variety of sorbents and contaminants has shown that ''K<sub>oc</sub>'' values are correlated with contaminant hydrophobicity. This allows ''K<sub>oc</sub>'' to be estimated using empirical correlations with the contaminant aqueous solubility or [[wikipedia: Partition coefficient | octanol-water partition coefficient]] (''K<sub>ow</sub>'') (Figure 4).  Using this approach, ''K<sub>d</sub>'' can be estimated using site specific measurements of ''f<sub>oc</sub>'' and literature values of contaminant properties.
-[[File:Allen-King1w2 Fig4.png|thumb|center|500 px| Figure 4. Empirical correlations between log ''K<sub>oc</sub>''  and log ''K<sub>ow</sub>''. Variations arise because the studies used different contaminant compounds and different field samples. Figure from Allen-King et al., 2002<ref name="Allenking2002" />, which also lists the correlation equations.]]
 [[File:Allen-King1w2 Fig5.png|thumb|right|400 px|Figure 5. The trichloroethene ''K<sub>oc</sub>'' versus the Hydrogen/Oxygen ratio of carbonaceous material. The sorption coefficient (per gram carbon) is 1-2 orders of magnitude greater for more condensed carbonaceous matter, as indicated by greater H/O ratios, compared to humic acid and peat. Calculations are from linear isotherms at a low aqueous concentration<ref name="Grathwohl1990" />.]]