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

Abstract

<span style="mso-ansi-language:EN-US" lang="EN-US">An attempt has been made to study the reaction of polar organic molecule <i>N</i>-(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 <i>N,N</i>-bipyrazole-substituted silica (Si<b style="mso-bidi-font-weight:normal">-</b>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 <span style="mso-ansi-language:EN-US" lang="EN-US">Si-NP2<b style="mso-bidi-font-weight: normal"> </b><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 <i>p</i>H and stirring time is studied. The optimum <i style="mso-bidi-font-style:normal">p</i>H values for the quantitative extraction of these metal ions are found to be 6.0-7.5, and at these <i>p</i>H values, the functionalized silica further improves and shows higher affinity; the sorption capacity is in range of 486–1472 <span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-char-type:symbol;mso-symbol-font-family:="" symbol"="" lang="EN-US">m<span style="mso-ansi-language:EN-US" lang="EN-US">mol g⁻¹ of chelating matrix. The extracted amounts are determined by atomic absorption measurements.

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