Solid-phase extraction of Hg(II), Zn(II) and Cd(II) from water using silica gel modified with bipyrazolic tripodal receptor

423-428An attempt has been made to study the reaction of polar organic molecule N-(hydroxymethyl)-3,5-dimethylpyrazole with a 3-aminopropyl trimethoxysilane silylant agent, previously anchored on a silica surface in a heterogeneous way, to yield the product N,N-bipyrazole-substituted silica (Si-NP2). The product has been characterized through elemental analysis, FTIR, 13C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore sizes, thermogravimetry curves and scanning electron microscope. The binding and extraction abilities of Si-NP2<b style="mso-bidi-font-weight: normal"> <span style="mso-ansi-language: EN-US" lang="EN-US">have been investigated for Hg(II), Zn(II) and Cd(II) by batch method and the effect of pH and stirring time is studied. The optimum pH values for the quantitative extraction of these metal ions are found to be 6.0-7.5, and at these pH values, the functionalized silica further improves and shows higher affinity; the sorption capacity is in range of 486–1472 mmol g−1 of chelating matrix. The extracted amounts are determined by atomic absorption measurements.