C,N-bipyrazole receptor grafted onto a porous silica surface as a novel adsorbent based polymer hybrid

• This is the first time has been synthesized and will be used as adsorbent.
• These systems can be operated indefinitely without loss of the organic molecules.
• The porous silica has a BET surface area of 550 m2/g and a pore volume of 0.8 cm2/g.
• Functional groups were distributed on the whole surface.
• They showed good separation and extraction capabilities for alkali and heavy metal ions.

A simple heterogeneous synthesis of pure adsorbent based polymer hybrid made by condensing a functionalized C,N-bipyrazole with a 3-glycidoxypropyl-trimethoxysilane silylant agent, previously anchored on a silica surface was developed. The formed material (SG2P) was characterized through elemental analysis, FT-IR spectroscopy, 13C NMR of solid state, scanning electron microscope (SEM), and was studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and B.J.H. pore sizes. The new material exhibits good thermal stability determined by thermogravimetry curves and good chemical stability was examined in various acidic and buffer solutions (pH 1–7). The binding and adsorption abilities of SG2P were investigated for Hg2+, Cd2+, Pb2+, Zn2+, K+, Na+ and Li+ cations and compared to the results of classical liquid–liquid extraction with the unbound C,N-bipyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the SG2P exhibits a high selectivity toward Hg2+ ion with no complexation being observed towards zinc and alkali metals. The extracted and the complexing cation percentages were determined by atomic absorption measurements.

The thermogravimetric curves reflect the thermal stability of this new product (SG2P) and showed an increase of mass loss allotted to the decomposition of the C,N-bipyrazole fraction immobilized on the surface of silica.Figure optionsDownload as PowerPoint slide