Mesoporous silica containing Si(CH2)3NHC(S)NHC2H5 functional groups in the surface layer

One-step synthesis technique of mesoporous SBA-15 type silica with thiourea Si(CH2)3NHC(S)NHC2H5 groups in the surface layer was developed. According to elemental analysis, the content of surface groups is 1.25 mmol/g, which is consistent with TGA data. FT-IR spectra of the obtained sample contain characteristic absorption bands of thiourea groups (NHC(S)NH), as well as polysiloxane network (SiOSi). The synthesized sample was studied by XRD, TEM, SEM, and adsorption method. It was demonstrated that the sample features porous microspheres ∼0.5 μm with well-ordered internal spatial structure of the hexagonal lattice type due to the usage of template P123 during synthesis. According to XRD and TEM, the diameter of pores is 4.2–5 nm and the wall thickness between them is 2.6 nm. These data are consistent with the structural-adsorption characteristics calculated from nitrogen adsorption–desorption isotherms: Ssp. = 510 m2/g, Vs = 0.47 cm3/g, and d = 4.3 nm. Equilibrium is established within 60 min during sorption of silver(І) and mercury(ІІ) ions from acidified aqueous solutions for this sample, and with the complexes are formed 1.1/1 for Ag+ and 0.8/1 for Hg2+ at metal/ligand ratio.

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► SBA-15 type silica with thiourea Si(CH2)3NHC(S)NHC2H5 groups was synthesized by one-pot route.
► TEM confirmed existence of mesopores (4.2–5 nm).
► Concentration of complexing thiourea groups on the surface of mesopores is 1.25 mmol/g.
► Obtained material can be used as sorbent for heavy and noble metals.