Sorption capacity of natural and modified montmorillonite in relation to copper ions in the presence of organic acids

Abstract

Natural montmorillonite (Sarigyukh deposit, Armenia) and its monosubstituted sodium form were
characterized by physical and chemical methods. The acid-base characteristics and X-ray pictures of the analyzed
samples are obtained. Sorption isotherms and kinetic characteristics are reported for sorption of copper
cations on natural and modified forms of montmorillonite in the presence of organic acids and without them.
It was found that sorption on cation-substituted sodium form of montmorillonite is higher than natural montmorillonite,
due to the increase in the capacity of cationic exchange. The presence of tartaric acid in the solution
leads to decrease of sorption of copper cations on all forms of montmorillonite, as in this case, the complex
compounds are present as copper tartarate in the solution. Alаnine insignificantly reduces the sorption of
copper cations on montmorillonite, due to a decrease pH of solution in sorption process and instability of
aminocomplexes of copper in acidic media.