African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12340

Full Length Research Paper

Kinetic modeling of concentrated acid hydrolysis of walnut green skin

  A. Arastehnodeh1*, M. Ardjmand1, M. A. Fanaei2 and A. A. Safekordi1  
  1Department of Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran. 2Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
Email: [email protected]

  •  Accepted: 28 December 2011
  •  Published: 12 January 2012



The overall goal of this experiment was to detect whether kinetic modeling can explain effects of temperature, acid concentration, time and solid contents on the production of glucose by concentrated acid hydrolysis of walnut green skin. For this purpose, sulfuric acid concentration of 20, 40 and 60% (w/w), processing temperature of 65, 80 and 90°C, reaction time of 120, 180 and 240 min and solid content of 5, 10 and 15% (w/w) were used as hydrolysis conditions. High performance liquid chromatography (HPLC) was used to analyze the products. The process was modeled by first-order irreversible reaction in series and kinetic constant, relating reaction time to glucose released. To relate temperature with kinetic constant and calculate activation energy, Arrhenius equation was employed. Optimal conditions occurred at 40% H2SO4, 90°C and 15% solid content for 285 min, which yielded a solution with 10.72 g glucose/L. In these conditions, 45% of the cellulose was hydrolyzed.


Key words: Kinetic modeling, fermentable sugar, acid hydrolysis, walnut green skin.


NOMENCLATUREα = Ratio between susceptible polymer to totala = Regression parameterAc0= Potential concentration of acetyl groupAc = Acetic acid concentration; CG0= Initial composition for CelluloseCmax= Maximum concentration of Glucose; E= Activation energyk1 = Rate of conversion of polymerk2= Rate of decomposition of monomertmax= Time for maximum concentration; = The monomer concentrationn = Regression parameterP0= The polymer concentration;R = Gas constant= Reaction temperatureR2= Regression parameterWGS= Walnut green skinWSR = Water solid ratiog/L = gram / literw/w% = Percentage weight/weightTT= Thousand ton.