Transport of a model diffusion probe in polyelectrolyte-surfactant hydrogels

Agarose Hydrogels Enriched by Humic Acids as the Complexation Agent

“…Therefore, copper is a traditional model metal used to study humic reactivity. The increase in the content of Cu(II) ions in agarose hydrogels enriched by humic acids can be considered as the result of this humic affinity observed also in our previous studies [24][25][26][27][28]. If we compare the contents of Cu(II) ions in hydrogels containing different humic acids with the contents of their acidic functional groups declared by IHSS [34,35], we can find that the content of Cu(II) ions in hydrogels increases with the increasing total acidity of studied humic acids.…”

“…In this work, the effect of standard humic acids as the complexation agents added in agarose hydrogels was studied by means of so-called diffusion-release experiments. Humic acids are known as substances which complex effectively with metal ions [25][26][27][28][29][30][31][32][33] and dyes [21][22][23][24]. Carboxylic functional groups, as well as aromatic structures and π−π interactions, are important in their reactivity.…”

“…In contrast, the content of copper is slightly higher. It is well known that humic acids have very high affinity to Cu(II) ions [24][25][26][27][28][30][31][32][33]. Therefore, copper is a traditional model metal used to study humic reactivity.…”

“…The knowledge of contents of diffusion probes was necessary for the mathematical description of their release from hydrogels. The effective diffusion coefficients D ef,h of Cu(II) ions and dyes in hydrogels were calculated on the basis of the following equation [26,36,37]:…”

“…The cuvettes filled with hydrogels were placed into stirred donor solutions (4 cuvettes in 200 cm 3 ). The diffusion probes have been diffusing into the hydrogel until a constant concentration throughout the whole hydrogel was achieved [25,26].…”