Inhibition of mild steel corrosion in H2SO4 solution by coconut coir dust extract obtained from different solvent systems and synergistic effect of iodide ions: Ethanol and acetone extracts

Saviour A. Umoren, Moses M. Solomon, Ubong M. Eduok, Ime B. Obot, Aniekemeabasi U. Israel

Research output: Journal PublicationArticlepeer-review

129 Citations (Scopus)

Abstract

Weight loss and electrochemical (open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy) techniques were used to assess the effectiveness of ethanol and acetone extracts of coconut coir dust as corrosion inhibitor for mild steel in 0.5 M H2SO4 solution at 30-60 °C. It was found that both ethanol and acetone extracts of coconut coir dust retard the dissolution of mild steel in 0.5 M H 2SO4 solution, but a pronounced effect was noted with ethanol extract. The inhibition efficiency increased with increase in extract concentration but decreased with rise in temperature, which is suggestive of physical adsorption mechanism. Addition of KI was found to synergistically enhance the protective ability of coconut coir dust extracts obtained from both solvent systems investigated. The synergistic effect was confirmed from the synergism parameter (S0) which was found to be greater than unity. Potentiodynamic polarization result suggests that coconut coir extracts functioned as mixed-type inhibitor. The adsorption of coconut coir dust extracts onto the mild steel surface followed Freundlich adsorption isotherm model. The mechanism of physisorption of the extracts onto the steel surface is proposed from the trend of inhibition efficiency with temperature which is corroborated by the values of activation parameters obtained from the experimental data.

Original languageEnglish
Pages (from-to)1048-1060
Number of pages13
JournalJournal of Environmental Chemical Engineering
Volume2
Issue number2
DOIs
Publication statusPublished - Jun 2014
Externally publishedYes

Keywords

  • Acid corrosion
  • Coconut coir dust
  • Corrosion inhibition
  • Mild steel
  • Synergistic effect

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology

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