Comparison of thermal and chemical stability of Cu-humic complexes

Abstract

This work is focused on comparison of the rmo-oxidative and chemical stability of copper complexes with humic acids. The humic acid was extracted from South Moravian lignite by standard alkaline extraction. The humic sample was used in two different forms: as solid powder and as hydrogel prepared by acidic precipitation of humate. Three various concentrations solutions of Cu2+ solutions were used for complexation of humic powder and gel, in order to study the influence of the initial concentration on both determined stabilities of the prepared complexes. Their chemical stability was assessed in terms of Cu2+ ion release from the humic acid structure into two different extraction agents (MgCl2 and HCl solutions). Their thermo-oxidative behavior was investigated employing thermal analysis (TGA).