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

Full Length Research Paper

Inhibitive and adsorptive effect of Parinari polyandra on mild steel corrosion in aqueous sulphuric acid

F. E. Awe
  • F. E. Awe
  • Department of Applied Chemistry, Federal University Dutsin-ma, Dutsin-ma, Nigeria.
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S. O. Idris
  • S. O. Idris
  • Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
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M. Abdulwahab
  • M. Abdulwahab
  • Department of Metallurgical and Material Engineering, Ahmadu Bello University, Zaria, Nigeria.
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E. E. Oguzie
  • E. E. Oguzie
  • Electrochemical and Material Science Research Laboratory, Department of Chemistry, Federal University of Technology Owerri, Owerri, Nigeria.
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  •  Received: 05 May 2015
  •  Accepted: 05 June 2015
  •  Published: 30 June 2015

Abstract

The inhibition of mild steel corrosion in 0.5 M sulphuric acid solution by ethanol extracts of Parinari polyandra as an eco-friendly inhibitor was studied at different temperatures by weight loss technique and linear polarization. The test plant extracts has a promising inhibitory action against corrosion of mild steel in the sulphuric acid media. The inhibition efficiencies increase with a corresponding increase in the concentration of the inhibitor. The adsorption of the inhibitor on mild steel surface is exothermic, spontaneous and is best described by Freundlich and Temkim adsorption models. Calculated values of activation energy, enthalpy of activation, entropy of activation, free energy of adsorption and the trend in the variation of inhibition efficiency with temperature, the mechanism of the process is by physical adsorption. Ethanol extract of Parinari polyandra is a good adsorption inhibitor for the corrosion of mild steel in sulphuric acid. Tafel polarization analyses indicate that the studied plant extract is a mixed type inhibitor.
 
Key words: Isotherm, polarization, adsorption, inhibitor, Parinari polyandra.