African Journal of
Pure and Applied Chemistry

  • Abbreviation: Afr. J. Pure Appl. Chem.
  • Language: English
  • ISSN: 1996-0840
  • DOI: 10.5897/AJPAC
  • Start Year: 2007
  • Published Articles: 357

Extraction of silica gel from Sorghum bicolour (L.) moench bagasse ash

Mupa M.
  • Mupa M.
  • Department of Chemistry, Bindura University of Science Education, P. Bag 1020, Bindura, Zimbabwe
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Hungwe C. B.
  • Hungwe C. B.
  • Department of Chemistry, Bindura University of Science Education, P. Bag 1020, Bindura, Zimbabwe
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Witzleben S.
  • Witzleben S.
  • Bonn-Rhein-Sieg University of Applied Sciences, Inorganic Chemistry and Materials Analysis, von Liebig Str. 20, 53359 Rheinbach, Germany.
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Mahamadi C.
  • Mahamadi C.
  • Department of Chemistry, Bindura University of Science Education, P. Bag 1020, Bindura, Zimbabwe
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Muchanyereyi N.
  • Muchanyereyi N.
  • Department of Chemistry, Bindura University of Science Education, P. Bag 1020, Bindura, Zimbabwe
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  •  Received: 03 January 2015
  •  Accepted: 12 February 2015
  •  Published: 26 February 2015

Abstract

Sweet sorghum (Sorghum bicolor (L.) moench), a crop that is grown by subsistence farmers in Zimbabwe was used to extract silica gel in order to assess its possible use as a raw material for the production of silica-based products. The gel was prepared from sodium silicate extracted from sweet sorghum bagasse ash by sodium hydroxide leaching. Results show that maximum yield can be obtained at pH 5 and with 3 M sodium concentration. The silica gel prepared at optimum pH 5 had a bulk density of 0.5626 g/cm3 and anestimated porosity of 71.87%. Silica gel aged over 10 h had improved moisture adsorption properties. X-ray fluorescence (XRF) determinations show that the silica content in the ash is 40.1%. Characterization of sweet sorghum ash and silica gels produced at pH 5, 7 and 8.5 by Fourier Transform Infrared spectroscopy gave absorption bands similar to those reported by other researchers.Transmission electron micrographs show that silica prepared under optimum conditions is amorphous and consisted of irregular particles. Sweet sorghum proved to be a potential low cost raw material for the production of silica gel.

 

Key words: Silica gel, sweet sorghum, extraction, ash, bagasse, X-ray powder diffraction (XRD).