Section: Chemistry of natural environments and objects
The aim of research is experimental modeling of gold, arsenic, copper, and lead ions interaction with humic acids. Importance of that study and choice of study subjects is coused by poor knowledge of the characteristics of the sorption interaction of these ions with humic acids. Arsenic, copper, and lead are, on the one hand, common pollutants accumulated in soils under anthropogenic impact, and on the other hand – pathfinder elements for gold deposits, which are used as indicators of gold mineralization in geochemical survey. The experiment was carried out in the range of heavy metals concentrations from 5 to 100 µg/cm3 in solution and at temperature of 298 K. The equilibrium concentrations of the elements were determined by inductively coupled plasma mass spectrometry. The experimental adsorption isotherms are described with the empirical Freundlich equation and the Langmuir monomolecular adsorption model. It was shown that the Langmuir model adequately describes the adsorption isotherms of Cu2+ and Pb2+ cations in the used concentration range. The sorption equilibrium constant and the limit adsorption were calculated for these elements. The sorption of arsenic is better described with the Freundich equation. Apparently, it is characterized by complex character of sorption interactions associated with a possible polymolecular adsorption mechanism, as well as with the change of form of arsenic in solution. A simulation experiment of influence of iron(III) ions onto the sorption of gold ions was conducted, which is important for determination of gold’s migration forms in soils with presence of iron oxides and hydroxides. It was shown that the increase of iron concentration had almost no effect on the amount of sorbed gold ions in the studied concentration range.
Keywords: sorption, humic acids, arsenic, gold, copper, lead
ISSN 1995-4301
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