COPPER(II) ION IMMOBILIZATION BY HUMIC ACID CONVERTED INTO POORLY SOLUBLE FORM
Humic acid (HA) isolated from peat has been applied for immobilization of Cu<sup>2+</sup> ions to remediate polluted soil. HA solubility has been decreased at рН ≥ 5 by its treatment with Fe<sup>3+</sup> ions (0.1 mmol/g HA). Sorption equilibriums in HA-Cu<sup>2+</sup>-Н<sub>2</sub>О system have been investigated at рН 3.5, 4.0 and 5.0 at 25<sup>0</sup>С. The results have been analyzed using isotherm equations of Henry, Langmuir and Freundlich. To specify the sorption mechanism, the IK-spectra of HA and sorption products have been registered. It has been shown, that HA sorption capacity and the bond of Cu<sup>2+</sup> with -СОО<sup>-</sup> ions increase, the molar coefficient of Н<sup>+</sup>/Cu<sup>2+</sup> exchange decreases with the increase of рН.