Nanocomposites and nanomaterials

Fabrication of magnetite-based core-shell nanoparticles with bifunctional amino-/mercapto- polysilsesquioxane layers
Muratova M.A.1,2, Stolyarchuk N.V.2, Tomina V.V.2, Melnyk I.V.2,3
1 National University of Kyiv-Mohyla Academy, 2 Skovorody Str., Kyiv-04655, Ukraine,
2 Chuiko Institute of Surface Chemistry, NAS of Ukraine, 17 General Naumov Str, Kyiv-03164, Ukraine, 
3 Institute of Geotechnics SAS, 45 Watsonova Str, Kosice-04001, Slovak Republic, E-mail: melnyk@saske.sk

Magnetically controlled nanoparticles covered by silica shell with different groups are widely used and researched due to their obvious advantages, such as ease of extraction, high content of functional groups and well-developed shell porous structure [1]. Composite materials based on magnetite nanoparticles functionalized with mercaptopropyl [2] and aminopropyl groups [3] have been already applied as adsorbents for the removal of heavy and precious metal ions from aqueous solutions, sorption of organic dyes, and for the production of biocatalysts due to enzyme fixing.
The proposed research is focused on the developing of a one-step sol-gel method for obtaining magnetic nanoparticles with a bifunctional surface layer (‒(CH2)3˗SH and ‒(CH2)3˗NH2), using bridged silanes 1,2­bis(triethoxysilyl)ethane and 1,4­bis(triethoxysilyl)benzene as structuring agents. These bissilanes promote the formation of an outer shell with high porosity (SBET = 630 – 980 m2/g) and also organic bridges are expected to improve the access of target ions to the functional groups by increasing the distance between them. The combination of amino and mercapto groups has to create a specific environment for metals during their adsorption on the surface of such carriers, which may cause their different behavior on the surface. Creating clusters of a particular structure on the surface can promote the selective adsorption of certain metal cations, which was the purpose of the work. 
The research was financed by APVV-19-0302.
1.	Melnyk, I.V., et al. Functionalization of the magnetite nanoparticles with polysilsesquioxane-bearing N- and S-complexing groups to create solid-phase adsorbents // Appl Nanosci.-2020.-10.- P. 2813–2825. 
2.	Melnyk I.V., et al. Protection of thiol groups on the surface of magnetic adsorbents and their application for wastewater treatment // Sci Rep.-2018.-8.-P. 8592.
3.	Melnyk I.V., et al. Magneto-sensitive adsorbents modifed by functional nitrogen-containing groups // Nanoscale Res Lett.-2016.-11.-P.61.