Abstract

The kinetics of Hg adsorption by poorly crystalline Al, Fe, Mn, and Si oxides in 0, 10-3, and 10-2 M NaCl solutions were investigated. The influence of Cl- on the Hg adsorption very significantly varied with the kinds of the hydrous oxides studied. The rates of Hg adsorption by the hydrous oxides of Al, Fe, and Si steadily decreased with increasing Cl- concentration in solution. The rate constants of the fast adsorption process of Hg by the oxides of Fe, Al, and Si decreased by 21.3, 6.5 and 6.4 times, respectively, in 10-2 M NaCl solution. In the same NaCl concentration, little decrease in the rate constant of the Hg adsorption by Mn oxide was observed. The effect of ionic strength and Na+ on the Hg adsorption by the oxides was not evident. The results indicate that the nature and properties of hydrous oxides which are commonly present in freshwater sediments merit close attention in the extent of the influence of a road deicing salt, NaCl, on the dynamics of Hg in aquatic environments.

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