Author(s)

Khaled S. Abou-El-Sherbini, Peter G. Weidler, Detlef Schiel, Mohey H. A. Amr, Henning Niemann, Shady El-Dafrawy, Wolfgang H. Höll

Anorganische Analytik, Labor 3.11, Physikalisch-Technische Bundesanstalt Braunschweig, Braunschweig, Germany.
Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, Egypt.
Department of Inorganic Chemistry, National Research Centre, Dokki, Egypt.
Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Campus Nord, Karlsruhe, Germany.
Research Department, Trace Elements Lab, Chemistry Administration, Cairo, Egypt.

Silica gel (SG) was synthesized via acidification of sodium silicate solution then doped with Fˉ or Zr(IV) in molar ratios of F/Si 3/100, and Zr/Si 0.75/100 and 3.75/100 and sintered at 500°C, 800°C and 1000°C. The samples were investigated by X-ray diffractometry, infrared absorption and Raman spectra, surface area measurement, and inductively coupled plasma-optical emission spectrometry-monitored silica hydrolysis. All samples are mesoporous with BET surface areas 181.5 - 523.9 m²·gˉ¹. The surface area of the silica samples decreases as the sintering temperature increases. The hydrolysis process of silica decreases as the sintering temperature increases and as the surface area decreases. The pH and the type of buffer solution affect the hydrolysis of silica samples due to a SN₂ reaction mechanism favored in basic media using ammonia buffer. Zr(IV) increases the stability of silica samples against the hydrolysis as confirmed by the structural investigation, surface area and silica hydrolysis. Fˉ observably decreases the silica hydrolysis process when presenting on the surface of SG.

Silica Gel; Doping; Hydrolysis; Fluorine; Zirconium

K. S. Abou-El-Sherbini, P. G. Weidler, D. Schiel, M. H. A. Amr, H. Niemann, S. El-Dafrawy and W. H. Höll, "Stabilization of Silica Gel against Hydrolysis by Doping with Fˉ or Zr(IV)," Green and Sustainable Chemistry, Vol. 4 No. 1, 2014, pp. 24-32. doi: 10.4236/gsc.2014.41005.