PREPARATION AND CHARACTERIZATION OF IONIC LIQUID CONTAINING SILICA BASED ADSORBENTS BY SOL-GEL METHOD FOR THE PRECONCENTRATION OF CHROMIUM IONS VIA SOLID PHASE MICRO EXTRACTION METHOD
Project no. 1365 · Status: Kapanmış · 2017
Summary
Chromium has a wide range of industrial application areas such as; metal plating, tanning pigment and coating industries. Chromium in aqueous solutions exist in a range of oxidation state from -2 to +6. Hexavalent chromium can be found in nature as Cr2O7-2, CrO4-2 and HCrO4- depending on the pH of the media and the redox potential of itself. Hexavalent chromium exhibits toxic effects for living organisms, therefore the allowable limit is kept at low concentrations. World Health Organization (WHO) has set this limit as 0.05 mg/L for the drinking waters. For that reason, in order to determine the trace amount of hexavalent chromium; a high selective process of pre-concentration techniques must be developed. In this study is Solid Phase Micro Extraction (SPME) technique is used to enrich the Cr(VI) ions in aqueous solutions. For this purpose, silica based adsorbents containing ionic liquids are synthesized by sol-gel method. Thus we can combine the synergetic effect of high chelating ability of ionic liquids and surface properties of silica substances. Both commercial (EMIMTf2N) and synthesized (A336[NO3]) ionic liquids are directly incorporated with sol-gel operation. Silica based adsorbents are being initiated with silica precursor (TEOS), water, alcohol and ionic water hydrolysis in the presence of an acid catalysts then completed with a condensation reaction. Physical and chemical characterization of adsorbent have been investigated by Fourier Transform Spectrophotometry (FTIR) and Scanning Electron Microscopy (SEM). Studies on extraction and pre-concentration have been achieved is used to in micro columns inlet stream contains 0.5 mg/L Cr(VI) solution. The stripping of Cr(VI) columns is studied by same concentrations of HCl, HNO3 and NaOH.