Contaminant Sorption

Sorption of contaminants can be included in the advection-dispersion equation by introducing a retardation factor  

Berkowitz et al. Contaminant Geochemistry Transport and Fate in the Subsurface Environment. 

the travel time for an adsorbed chemical, t, can be related to the travel 

Equation 11.4 also can be written as = vR, where denotes the average velocity of a sorbing contaminant. Thus, the concentration profile of a sorbing contaminant is retarded, relative to a nonsorbing contaminant, as shown schematically in Fig. 10.1c. 

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Boyd SA, Jaynes WF (1994) Role of layer charge in organic contaminant sorption by organo-clays. In Mermut AR (ed) Layer charge characteristics of 2 1 silicate clay minerals. CMS Workshop Lecture Series, vol 6, The Clay Minerals Society, Boulder, CO, pp 48-77... 

Brixie JM, Boyd SA (1994) Treatment of contaminated soils with organoclays to reduce leachable pentachlorophenol. J Environ Qual 23 1283-1290 Brown MJ, Burris DR (1996) Enhanced organic contaminant sorption on soil treated with cationic surfactants. Ground Water 34 734-744 Burris DR, Antworth CP (1992) In situ modification of an aquifer material by a cationic surfactant to enhance retardation of organic contaminants. J Contam Hydrol 10 325-337... 

Recently, Burkhard (2000) reviewed contaminant sorption by dissolved organic matter. Using several hundreds of UCC-water partition coefficients (A doc) reported in these studies, he found that UCC-water partition coefficients for naturally occurring DOC (humic and fulvic acids, sediment pore water, soil pore water, groundwater, and surface water) was best described by... 

Apparent hysteresis also may be caused by other phenomena. During the consecutive extractions and dilution steps used as a common technique in desorption studies, weathering of the sorbent may occur, resulting in a possible increase of contaminant sorption and decrease in its release. Degradation of the contaminant induced by physicochemical or biological factors, or a volatilization process leading to a decreased contaminant concentration in solution, are additional factors affecting a true hysteresis result. 

Reduces contaminant sorption, facihtating the transport of dissolved contaminants. 

Zhuang, J. and Yu, G.-R. (2002) Effects of surface coatings on electrochemical properties and contaminant sorption of clay minerals. Chemosphere, 49(6), 619-28. 

In this project, we used high-purity HDTMA to manufacture the SMZ, since all of our laboratory testing had been done using this surfactant. Clearly, the bulk cost of SMZ could be greatly reduced if a less expensive surfactant were used. Surfactant mixtures which contain lower molecular-weight cationic surfactants, in addition to HDTMA, are available at lower cost. Limited experimentation with these lower-purity formulations indicated they produced SMZ that was less stable chemically and had a lower contaminant sorption capacity than SMZ prepared with pure HDTMA. The effectiveness of SMZ prepared from these alternative surfactant formulations warrants further examination, however. 

Mao, J. D., and Schmidt-Rohr, K. (2006). Absence of mobile carbohydrate domains in dry humic substances proven by NMR, and implications for organic-contaminant sorption models. Environ. Sci. Technol. 40,1751-1756. 

Since SOM is most often the main component responsible for sorption of organic chemicals, e.g., contaminants (Fig. 4.19), researchers use octanol (an eight-carbon alcohol) to simulate organic matter-hydrophobic contaminant sorption phenomena. 

Zhao, D. SenGupta, A. K. Zhu, Y. Trace Contaminant Sorption through Polymeric Ligand Exchange, Ind. Eng. Chem. 1995, 34, 2676-2683. 

ASTM (1987) 24-hour batch-type measurement of contaminant sorption by soils and sediments. In Annual Book of ASTM Standards Water and Environmental Technology. Philadelphia, Pennsylvania, vol. 11.04, pp. 163-167. 

Organic contaminants in surface and subsurface systems are typically distributed by sorption between the aqueous phase and natural solid phases. The extent to which such contaminants are sorbed significantly affects their transport and distribution, their impacts on the ecosystem, and the selection of strategies for their removal. In cases of hydrophobic contaminants, sorption is governed by a complex combination of interactions associated with solute repulsion from the aqueous phase and solute attraction to particular solid phases and interfaces. The variety of thermodynamically driven and kinetic or mass-transport-controlled solute-sorbent interactions that may occur in natural systems were summarized by Weber et al. (1). 

Choate, L.M. (2002). The effect of variations in soil organic matter with particle size on organic contaminate sorption and its relationship to dermal exposure, Ph.D. thesis, Colorado School of Mines, Golden. 

In addition, many remediation processes require information concerning the diffusion of various gases through the soil. Diffusion may possibly be a rate-limiting step in aerobic biodegradation as these processes require sufficient amounts of oxygen in the soil. Brusseau (1991) noted that diffusion is often the rate-limiting step in contaminant sorption and desorption from soil. 

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