The effect of sulphuric acid activation on the crystallinity, surface area, porosity, surface acidity, and bleaching power of a bentonite

Noyan H., Oenal M., Sarikaya Y.

Food Chemistry, cilt.105, sa.1, ss.156-163, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 105 Sayı: 1
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1016/j.foodchem.2007.03.060
  • Dergi Adı: Food Chemistry
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.156-163
  • Anahtar Kelimeler: acid activation, bentonite, bleaching, porosity, surface acidity, surface area, BETA-CAROTENE ADSORPTION, VEGETABLE-OILS, PALM OIL, PHYSICOCHEMICAL PROPERTIES, MONTMORILLONITE CLAY, CATALYST SURFACES, AQUEOUS-SOLUTION, INORGANIC ACIDS, COTTONSEED OIL, MECHANISM
  • Ankara Üniversitesi Adresli: Evet

Özet

The Hançi{dotless}li{dotless} (Keskin, Ankara, Turkey) bentonite was activated with H2SO4 by dry method at 97 °C for 6 h to obtain optimum parameters for imparting a maximum bleaching power towards soybean oil. The H2SO4 content in dry bentonite-acid mixture was changed between 0% and 70%. The natural and activated samples were examined by X-ray diffraction (XRD), N2 adsorption-desorption, and n-butylamine adsorption (from the solution in cyclohexane). The specific surface area (S), specific micro-mesopore volume (V), mesopore size distribution (PSD), and surface acidity (nm) of the samples were determined. The bleaching power (BP) of each sample for alkali-refined soybean oil was determined. The S, V, nm, and BP increase after activation at various acid contents up to 40% H2SO4 without any considerable change in crystal structure of the smectite. The BP is controlled more by the PSD rather than other adsorptive properties of the bleaching earth. The optimum parameters for activation to obtain maximum bleaching power, are H2SO4% = 50-60, S = 250-230 m2 g-1, V = 0.46-0.47 cm3 g-1, nm = 9.0 × 10-4-8.4 × 10-4 mol g-1 and PSD mainly distributed between 1.4 and 6.0 nm. © 2007 Elsevier Ltd. All rights reserved.