TRANSPORT AND IMMOBILIZATION OF PHARMACEUTICALS IN HUMIC HYDROGEL

Pharmaceuticals can be found in soil and aquatic environments as a result of human activity.They are released into the environment where they undergo soil sorption, photodegradation, and chemical transformation.It is known that their migration ability and toxicity can be significantly affected by interactions with organic matter.The interactions can result in their immobilization in humic structure and decrease in their bioavailability.Humic substances as important constituents of natural organic matter are investigated from point of view of their interactions with different pollutants (including pharmaceuticals) mainly by means of traditional batch adsorption experiments.Our approach is different.Humic substances are used in the form of hydrogel which can be considered as a model system of soil with characteristic content of organic matter.The hydrogel form is advantageous for its defined parameters which can be reflected in initial and boundary conditions necessary for mathematical description of transport in the system.Ibuprofen (sodium salt) was studied from point of view of its transport and immobilization in humic hydrogel by the method of instantaneous planar source.It means that small defined amount of diffusing substance is placed on the circular surface of cylinder-shaped hydrogel (placed in glass tube to achieve one-dimensional diffusion).Diffusion study was complemented by adsorption experiments to compare traditional and our novel approaches.The mobility in humic systems as well as the immobilization ability and their effect on the bioavailability of pharmaceutical are discussed.