Reactivity and transport properties of metal ions are important both for evaluating and understanding role of humic acids in natural systems and human-driven applications as solving their structural questions. This paper focuses on metal ions diffusion and immobilization in humic hydrogels. Humic acids were purchased from International Humic Substances Society (isolated from different matrices - peat, soil, leonardite, water) and extracted from lignite mined in Czech Republic. Copper(II) ions were chosen as a model example of reactive metal for the diffusion experiments. Previous works showed that transport of metal ions in humic gels were strongly influenced by reactivity of humic acids. Therefore samples isolated from different sources resulted in changes in the content of acidic functional groups and different diffusivity metal ions in prepared hydrogels. The diffusion coefficients of copper(II) ions, determined in this work, showed the significant dependence on reaction ability of humic hydrogels. Lower amounts of the acidic functional groups caused the increase of the effective diffusion coefficient. In general, diffusion experiments seem to provide valuable method for reactivity mapping studies on humic substances.Keywords: humic acids, diffusion, reactivity, immobilization, copper
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