Polysiloxane surface modified with bipyrazolic tripodal receptor for quantitative lead adsorption

A new silica gel compound modified N,N-bis(3,5-dimethylpyrazol-1-ylmethyl) amine (SiN2Pz) was synthesized and characterized by elemental analysis, FT-IR, 13C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area and BJH pore sizes. The new surface exhibits good chemical and thermal stability determined by thermogravimetry curves (TGA). The effect of pH and stirring time on the adsorption of Pb(II) were studied. The process of metal retention was followed by batch method and the optimum pH value for the quantitative adsorption of this toxic metal ion was 7. At this pH value, the new functionalized polysiloxane presents further improvements and shows higher affinity (123 mg of Pb2+/g of silica) for the effective adsorption of Pb(II) compared to others described sorbents. The extracted amounts of Pb(II) were determined by atomic absorption measurements.