Normal phase sorption model

Figure 4 shows phenanthrene and naphthalene sorption isotherms to kaolinite covered with varying levels of sorbed surfactant these levels of surfactant coverage correspond to the different regions existing in the surfactant sorption isotherms discussed earlier (Fig. 1). The linearity of each isotherm was evaluated using Freundlich and linear sorption models. It is apparent from Fig. 4 and Table 4 that HOC partitioning to kaolinite with and without adsorbed surfactants results in linear or near-linear isotherms. As the amount of surfactant adsorbed on the kaolinite surface increased, the sorption of phenanthrene and naphthalene to the solid phase also increased. However, upon normalizing by the amount of sorbed surfactant present, the sorbed surfactant partition coefficient (Kss) decreased with increasing sorbed surfactant amounts (Table 4).

Figure 12. Normalized, -weighted arsenic EXAFS spectra (soiid lines in a) and Fourier transforms (solid lines in b) of As(V) sorbed to S-Mn02 and birnessite and in an Mn(ll)-As(V) precipitate. Non-linear, least-squares fits to raw EXAFS data are plotted as dotted lines. The spectra of all sorption samples appear very similar, but sorption sample spectra are distinct from the model precipitate. Peak positions in FTs are not corrected for phase-shift effects, and are therefore approximately 0.5 A shorter than the true distance. From Foster et al. (submitted) reprinted with permission.

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