Hydroxypropyl methylcellulose as a polymeric corrosion inhibitor for aluminium
Abstract
Purpose
The paper aims to investigate the effectiveness of hydroxypropyl methylcellulose (HPMC) as corrosion inhibitor for aluminium in 0.5 M H2SO4 solution.
Design/methodology/approach
This study was carried out using weight loss and electrochemical techniques. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of inhibitor system. Quantum chemical computations were performed using density functional theory to assess the parameters responsible for the inhibition process and also to analyse the local reactivity of the molecule.
Findings
HPMC inhibited aluminium corrosion in the acidic environment. The inhibition efficiency was found to depend on concentration of the inhibitor. Impedance results reveal that HPMC is adsorbed on the corroding metal surface. Polarization results show that the dissolution reaction is due to destabilization of the passive oxide film on the Al surface. Adsorption of the inhibitor is approximated by Freundlich adsorption isotherm and the calculated standard free energy of adsorption indicates weak physical interaction between the inhibitor molecules and aluminium surface. This can be attributed to preferential interaction of the active sites with the passive oxide layer. The calculated quantum chemical parameters show good correlation with the inhibition efficiency.
Practical implications
HPMC could find possible application as a polymeric thickener and additive to improve corrosion resistance and barrier properties of anticorrosion paints.
Originality/value
This paper provides novel information on the inhibitive characteristics of HPMC under the stated conditions. The inhibitor systems provide an effective means for suppressing aluminium corrosion even in highly aggressive acidic environments.
Keywords
Acknowledgements
This research work is supported by TWAS, the Academy of Sciences for the Developing World, under the TWAS grants for Research Units in Developing Countries Program (TWAS-RGA08-005) and also by the Tertiary Education Trust Fund (TETFund) research projects intervention, for the Federal University of Technology, Owerri. Their supports are highly acknowledged.
Citation
Okechi Arukalam, I., Chimezie Madufor, I., Ogbobe, O. and E. Oguzie, E. (2014), "Hydroxypropyl methylcellulose as a polymeric corrosion inhibitor for aluminium", Pigment & Resin Technology, Vol. 43 No. 3, pp. 151-158. https://doi.org/10.1108/PRT-05-2013-0037
Publisher
:Emerald Group Publishing Limited
Copyright © 2014, Emerald Group Publishing Limited