Magnetite–Activated Carbon Nanocomposites: Synthesis, Sorption Properties, and Bioavailability

Two approaches were considered in searching for an efficient procedure for preparing magnetic nanocomposites based on activated carbon and magnetite nanoparticles by chemical precipitation: preliminary synthesis of magnetite nanoparticles by chemical precipitation from solutions of bi- and trivalent iron salts, followed by introduction of the nanoparticles into the activated carbon matrix, and synthesis of magnetite nanoparticles in the activated carbon matrix. A comparative analysis of the content of magnetite nanoparticles and functional characteristics (textural parameters, sorption capacity, saturation magnetization, and coercive force of the nanocomposites) was made. The ex situ synthesis proved to be the best procedure for preparing nanocomposite sorbents based on activated carbon and magnetite nanoparticles by chemical precipitation, as judged from the yield and functional characteristics of the target product. In biological testing, the maximal harmless (inactive) concentration of the magnetic nanocomposite in the test system with microalgae appeared to be higher by an order of magnitude than that in the test system with ciliates.