EFFECT OF DISSOLVED ORGANIC MATTER AND ...

Preprints of Extended Abstracts

Vol. 41 No. 1

GENERAL PAPERS Organized by M.L. Trehy Symposia Papers Presented Before the Division of Environmental Chemistry American Chemical Society San Diego, CA April 1-5, 2001

EFFECT OF DISSOLVED ORGANIC MATTER AND CATIONIC SURFACTANT ON THE DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS Jung-Won Moon and Jae-Woo Park National Subsurface Environmental Research Laboratory (NSERL) Dept. of Environmental Science and Engineering, Ewha Womans University, 11-1 Daehyon-Dong, Seodaemun-Gu, Seoul 120-750, South Korea

The widespread occurrence of polycyclic aromatic hydrocarbons (PAHs) in soil and groundwater systems has become an important environmental concern. A number of studies have focused on the fate and transport of these pollutants and their remedial technologies. It has been generally recognized that it is difficult to use ‘pump and treat’ to clean up contaminated sites by PAH because of its secondary contamination. As one of their alternatives, immobilization technique is to promote the sorption of organic pollutants in soil, and sand or clay minerals coated by cationic surfactant can prevent the spread of them. Various environmental factors, such as pH, extent of surfactant coverage, presence of dissolved organic matters (DOM) and ions, can be the controlling factors of the successful application of the technique(Boyd et al., 1988; Lee et al., 1989; Lee et al., 1990). DOMs, which are ubiquitous in aquatic systems, are largely composed of humic substances and tend to bind the PAHs owing to their high content of organic carbon(Zimmer et al., 1989). Therefore, it can be considered as both mobile phase for enhancing the solubility of PAH and sorbed phase itself on soil particle for retarding the mobility of them(Karickoff et al., 1979;Chiou et al., 1987;McCarthy et al., 1989;Magee et al., 1991;Liu et al., 1993;Johnson et al., 1995). In order to demonstrate how the sorption capacity of surfactant-modified soil for the organic contaminant is influenced by DOMs, a series of batch experiments was performed with cetylpyridinium chloride (CPC)-coated sand. To describe the overall

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mass distribution of PAH in the systems, multiphase mass distribution (MMD) model was developed and compared with overall mechanistic sorption (OMS) model, as shown in Figure 1(Lee et al, 1998;Park et al, 1999). The results showed that the soil-water distribution coefficient (K) of phenanthrene was reduced with increasing DOM concentration in the system. The extent of K-drop was remarkable for 1.746mg/g-coated sand, which yielded the highest sorption capacity on both phenanthrene without DOM and DOM itself. This denotes that DOM can compete with phenanthrene for available adsorption sites. In addition, the PAH-binding constant by DOM in the aqueous phase (KP 1,2) was determined by fluorescence quenching. KP 1,2 in the multiphase system was inconsistent with the PAH-DOM in the aqueous phase, suggesting the relationship between 2 phases can be different from those of multiphase. The estimation of K by OMS model was not in agreement with the experimental result, suggesting K value is dependent on the systems condition. The relative mass distribution of phenanthrene was predicted with MMD model as shown in Figure 2. The relative mass distribution was dependent on DOM concentration and type of sorbent. The results are quite different, depending on the cationic surfactant coverage on the sand. At low coverage, the sequence of mass distribution coefficient of phenanthrene was KP 1,2 > KP 1,3> KP 1,4, which depends on the mass of aqueous phase DOM. On the other hand, KP 1,3 >KP 1,2 > KP 1,4 was observed at high coverage, which indicates the distribution of DOM is as important as that of PAH.

Phase

Phase P

K

1,2

DOM

PAH P

P K 1,4

K

1,3

K

DOM 2,3

Phase

Phase

DOM

CPC-coated Sand

Figure 1. Description of the multiphase sorption system in the immobilization zone.

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0.000 mg/g

1.746 mg/g 1

Relative mass distribution ratio

Relative mass distribution ratio

1

P1 P2 P3 P4 0

P1 P2 P3 P4 0

2

5

8

10

2

HA Concentration(mg/L)

5

8

10

HA Concentration(mg/L)

Figure 2. Prediction of relative mass distribution of phenanthrene to cationic surfactantmodified sand (0.000 and 1.746 mg/g) in the presence of DOM by multiphase mass distribution (MMD) model.

References Boyd, S.A., Shaobai Sun, Lee, J.F., and Mortland, M.M. 1988. Pentachlorophenol sorption by organo-clays. Clays and Clay Minerals. Vol. 36, No. 2, 125-130. Chiou, C.T., Kile, D.E., Brinton, T.I., Malcolm, R.L., Leenheer J.A., and MacCarthy, P. 1987. A comparison of water solubility enhancements of organic solutes by aquatic humic materials and commercial humic acids. Environ. Sci. Technol. 21, 1231-1234. Johnson, W.P. and Amy, G. 1995. Facilitated transport and enhanced desorption of polycyclic aromatic hydrocarbons by natural organic matter in aquifer sediments. Environ. Sci. Technol. 29, 807-817. Karickhoff, S.W., Brown, D.S., and Scott, T.A. 1979. Sorption of hydrophobic pollutants on natural sediments. Water Res. 13, 241-248. Lee, J.F., Crum, J.R., and Boyd, S.A. 1989. Enhanced retention of organic contaminants by soils exchanged with organic cations. Environ. Sci. Technol. 23, 1365-1372. Lee, J.F., Mortland, M.M. Chiou, C. T. Kile, D.E., and Boyd, S.A. 1990. Adsorption of benzene, toluene, and xylene by two tetramethylammonium-smectites having different charge densities. Clays and Clay Minerals. Vol. 38, No. 2, 113-120. Lee, C-L. and Kuo, L-J. 1999. Quantification of the dissolved organic matter effect on the sorption of hydrophobic organic pollutant: application of an overall mechanistic sorption model. Chemosphere. Vol. 38, No. 4, 807-821. Liu, H. and Amy, G. 1993. Modeling partitioning and transport interactions between natural organic matter and polynuclear aromatic hydrocarbons in groundwater. Environ. Sci. Technol. 27, 1553-1562. Magee, B.R., Lion, L.W., and Lemley, A.T. 1991. Transport of dissolved organic macromolecules and their effect on the transport of phenanthrene in porous media. Environ. Sci. Technol. 25, 323-331. McCarthy, J.F. and Zachara, J.M. 1989. Subsurface transport of contaminants. Environ. Sci. Technol. 23, 496-502.

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Park, J-W. and Boyd, S.A. 1999. Sorption of chlorobiphenyls in sediment-water systems containing nonionic surfactants. J. Envrion. Qual. 28, 945-952 Zimmer, G., Brauch, H.J., and Sontheimer, H. 1989. Aquatic humic substances: Influence on fate and transport of pollutants. Advances in Chemistry Series 219 (eds: Suffet I. H. and MacCarthy P.), Washington D. C., American Chemical Society

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