Synthesis of bridged polysilsesquioxane xerogels with thiourea groups

Two xerogels with the ligand groups concentration 1.0 and 1.8 mmol gs−1 were prepared by sol-gel method from 1,2-bis(triethoxysilyl)ethane and trifunctional silane with thiourea groups [≡Si(CH3)2NHC(S)·NHC2H5]. It is shown that the increase in relative amount of structuring agent does not cause the increase in the specific surface value and the other parameters of porous structure. It arises from the significant increase in gel formation time in this system. It is found that synthesized xerogels can adsorb Hg2+ ions from the acidified water solutions. In this case in the surface layer formation of complexes of mercury(II) of different composition and with coordination sphere of different nature is possible due to thione-thiol tautomerism characteristic of thiourea group.