Synthesis and Adsorption Properties of 4-Vinylpyridine and Styrene Copolymers In Situ Immobilized on the Silica Surface

O.Yu. Kychkyruk1, O. U. Kondratenko1, E.S. Yanovska2, L.O. Vretik2, 
O.A. Nikolaeva2, D. Sternik3
1Ivan Franko Zhytomyr State University, 42 Pushkina  Str., 10008 Zhytomyr, Ukraine
2Taras Shevchenko Kyiv National University, 12 L. Tolstogo Str., 01033 Kyiv, Ukraine,
3Maria Curie-Skłodowska University, 2 Maria Curie-Sklodowska Sq., 20-031 Lublin, Poland

Pyridine and its derivatives are well-known ligands that form strong complex compounds with ions of most transition metals. Complexation processes are characteristic of polymers containing pyridine therefore modification of the surface of porous inorganic materials with pyridine-containing polymers will provide new composite materials that can be used as effective sorbents, that can form complex compounds, for metal cations due to their complexation with pyridine nitrogen atoms of immobilized polymer. One of the promising ways to create such organo-mineral composite materials with interesting and valuable sorption properties is the in situ immobilization of the polymer on the surface of a porous inorganic carrier, which consists in the direct formation of an immobilized polymer layer in the presence of particles of inorganic carrier.
This work is devoted to in situ immobilization on the surface of silica gels of a number of copolymers of 4-vinylpyridine and styrene with ratios from 6: 1 to 1: 6 and the to study of their sorption properties relative to copper ions Cu(II), Pb(II) and Fe(III).
The fact heterophase polymerization passage was confirmed by IR-spectroscopy. From a comparison of the IR spectra of the synthesized composites, it follows that with an increase in the amount of styrene in the copolymer, the intensity of the absorption bands in the region from 1420 cm-1 to 1622 cm-1 decreases, which indicates a decrease in the number of immobilized copolymers. According to the results of thermogravimetric analysis, it was found that the immobilized polymers decompose in the temperature range from 100 to 60°C and with an increase in the amount of styrene in the composition of the immobilized copolymers, the mass fraction of the immobilized copolymer in the composite decreases, and in this way, the data of IR spectroscopy, thermogravimetric analysis are consistent with each other.
A comparison of the sorption capacity of the synthesized composites according to Cu(II), Pb(II) and Fe(III) ions shows that among all the synthesized composites, the best sorption properties according to these ions are inherent in silica gel, in situ modified with styrene copolymer and 4-vinylpyridine with an initial ratio of 1: 3.