Nanocomposites and nanomaterials 

Synthesis and sorption properties of natural aluminosilicate minerals of Ukraine with adsorbed poly [8-oxyquinoline methacrylate] on toxic metal ions

Savchenko1, E. Yanovska1,  L. Vretik1, D. Sternik2, O. Kychkyruk3

1 National Taras Shevchenko University of Kyiv,
60, Volodymyrska str., 01601 Kyiv, Ukraine
E-mail: iras@univ.kiev.ua
2 Maria Curie-Skłodowska University, pl. Maria Curie-Skłodowskiej 3, 20‑031 Lublin, Poland
3 Ivan Franko Zhytomyr State University, 40 Velyka Berdychivska St., 10008 Zhytomyr, Ukraine

To solve specific environmental problems, in particular for wastewater treatment of individual industries, it is advisable to use composite materials based on natural minerals, which are industrially extracted in Ukraine. The main methods of fixing polymers on the surface of inorganic carriers are physical and chemical fixation, sol-gel method and in situ immobilization, each of which has its advantages and disadvantages.
New organo-mineral composite materials were obtained by adsorption of poly [8-oxyquinoline methacrylate] synthesized by initiated radical polymerization on the surface of a number of natural aluminosilicate minerals from Ukrainian deposits (clinoptilolite, saponite and vermiculite).
Immobilization of poly [8-oxyquinoline methacrylate] on the surface of selected minerals was confirmed using IR spectroscopy and thermogravimetric analysis combined with mass spectroscopy. Using thermogravimetric analysis, it was found that the mass fraction of polymer in the composition of the composite based on clinoptilolite is - 21.4%, saponite - 23%, and vermiculite - 24%.
From the analysis of photographs of the surface of the synthesized composites obtained by scanning electron microscopy, it follows that the polymer covers the surface of all minerals with a thin layer and the porosity of their surface is significantly reduced.
As a result of studying the sorption capacity of the synthesized composites with respect to Pb (II), Cu (II) and Fe (III) ions, it was found that the composite based on clinoptilolite has the best sorption characteristics with respect to the studied ions. Its sorption capacity in comparison with that for the original mineral increases relative to Cu (II) ions by 10.5 times, relative to Pb (II) ions - by 3.4 times; relative to Fe (III) - 2.3 times.
All synthesized composites have a slightly higher sorption capacity for Pb (II), Cu (II) and Fe (III) ions compared to the capacity for composites obtained by in situ immobilization of poly [8-oxyquinoline methacrylate], but it is observed in a narrower range of initial concentrations of metal ions. 
This fact can be explained by the fact that the adsorption of transition metal ions on the surface of synthesized composites can occur in two ways - due to the complexation of metal ions with molecules of immobilized polymer and adsorption of metal ions into pores and mineral channels. With a significant degree of coating of the surface of minerals with polymer, which takes place during the adsorption of the finished polymer on their surface, the second mechanism ceases to work and the sorption of metal ions occurs only due to complexation. Complexation is more intense than in situ immobilization of the polymer, as a result of more active centers and their better availability. And as a result of in situ immobilization of the polymer, the pores of the minerals remain open and the sorption of large amounts of metal ions occurs in both ways.