The presence of pharmaceuticals in nature systems poses a threat to the environment, plants, animals, and, last but not least, human health. Their transport in soils, waters, and sediments plays important roles in the toxicity and bioavailability of pharmaceuticals. The mobility of pharmaceuticals can be affected by their interactions with organic matter and other soil and water constituents. In this study, a model agarose hydrogel enriched by humic acid as a representative of organic matter is used as a transport medium for pharmaceuticals. Sulphapyridine (as a representative of sulphonamide antibiotics) and diclofenac (as a representative of widely used non-steroidal anti-inflammatory drugs) were chosen for experiments in diffusion cells. Pharmaceuticals were passed through the hydrogel from the donor solution to the acceptor compartment and could interact with humic acids incorporated in the hydrogel. The lag time was prolonged if the hydrogel was enriched by humic acids from 134 to 390 s for sulphapyridine and from 323 to 606 s for diclofenac. Similarly, the incorporation of humic acids in the hydrogel resulted in a decrease in the determined diffusion coefficients. The decrease was stronger in the first stage of the experiment when diffusing particles could interact with vacant binding sites.

• Keywords
• diclofenac, humic acid, hydrogel, sulphapyridine, transport,
• MeSH
• Diffusion MeSH
• Diclofenac * chemistry   MeSH
• Humic Substances * analysis   MeSH
• Hydrogels * chemistry   MeSH
• Pharmaceutical Preparations chemistry   MeSH
• Sepharose * chemistry   MeSH
• Sulfapyridine chemistry   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Diclofenac * MeSH
• Humic Substances * MeSH
• Hydrogels * MeSH
• Pharmaceutical Preparations MeSH
• Sepharose * MeSH
• Sulfapyridine MeSH

The mobility of heavy metals in natural soil systems can be affected by the properties and compositions of those systems: the content and quality of organic matter as well as the character of inorganic constituents. In this work, the diffusion of copper(II) ions in humic hydrogels with incorporated calcium(II), magnesium(II), and iron(III) ions was investigated. The methods of instantaneous planar source and of constant source were used. Experimental data yielded the time development of the concentration in hydrogels and the values of effective diffusion coefficients. The coefficients include both the influence of the hydrogel structure and the interaction of diffusing particles with the hydrogel. Our results showed that the presence of natural metal ions such as calcium, magnesium, or iron can strongly affect the diffusivity of copper in humic systems. They indicate that the mobility of copper ions depends on their concentration. The mobility can be supported by higher contents of copper in the system. While the incorporation of Ca and Mg resulted in the decrease in the diffusivity of copper ions, the incorporation of Fe(III) into humic hydrogel resulted in an increase in the diffusivity of Cu(II) in the hydrogel in comparison with pure humic hydrogel.

• Keywords
• Calcium, Copper, Diffusion, Humic acid, Hydrogel, Immobilization, Iron, Magnesium,
• MeSH
• Magnesium * chemistry   MeSH
• Humic Substances * MeSH
• Ions MeSH
• Copper * chemistry   MeSH
• Soil chemistry   MeSH
• Calcium * chemistry   MeSH
• Iron * chemistry   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Magnesium * MeSH
• Humic Substances * MeSH
• Ions MeSH
• Copper * MeSH
• Soil MeSH
• Calcium * MeSH
• Iron * MeSH