Abstract
AbstractInhibition effect of the synergistic combination of thymus mastichina and illicium verum oil extracts (TMAV) on the corrosion inhibition of low carbon steel in 0.5 M H2SO4and HCl solution was studied by weight loss analysis, potentiodynamic polarization, open circuit potential measurement, ATF-FTIR spectroscopy, and optical microscopy and macroscopic characterization. Results from weight loss shows TMAV performed more effectively in H2SO4solution compared to HCl with optimal inhibition efficiency of 81.24% and 68.33%. Effective inhibition performance was observed at all TMAV concentration in H2SO4compared to HCl where TMAV performed poorly until 5% concentration. The optimal inhibition performances from potentiodynamic polarization are 80.85% and 70.43%. The corresponding corrosion current density and polarization resistance are 7.16 × 105A/cm2and 8.01 × 105A/cm2, and 331.73 and 284 Ω. TMAV exhibited mixed type inhibition effect in both acid solutions, strongly influencing the anodic-cathodic plot configurations with respect to concentration. Open circuit potential plots without TMAV were significantly electronegative compared to the plots at 1% and 5% TMAV concentration which were relative electropositive due to decreased thermodynamic tendency of the carbon steel to corrode. The corresponding plots at 1% and 5% TMAV concentration from HCl solution were thermodynamically unstable with significant active-passive corrosion behaviour. TMAV inhibited through chemisorption adsorption according to Langmuir and Freudlich adsorption isotherms in H2SO4solution, and Frumkin and Freundlich adsorption isotherms in HCl solution with correlation coefficient values between 0.7 and 0.9. FTIR spectroscopic analysis exposed the functional groups and atomic bonds responsible for corrosion inhibition.
Highlights
Corrosion is the progressive oxidation and degradation of metallic and non-metallic materials by chemical and/or electrochemical interaction reaction with their environment [1,2,3]
Inhibition effect of the synergistic combination of thymus mastichina and illicium verum oil extracts (TMAV) on the corrosion inhibition of low carbon steel in 0.5 M H2SO4 and HCl solution was studied by weight loss analysis, potentiodynamic polarization, open circuit potential measurement, ATF-FTIR spectroscopy, and optical microscopy and macroscopic characterization
Potentiodynamic polarization plots of Low carbon steel (LCS) corrosion at specific TMAV concentration in 1 M H2SO4 and HCl solution are shown in Figures 1(a) and 1(b)
Summary
Corrosion is the progressive oxidation and degradation of metallic and non-metallic materials by chemical and/or electrochemical interaction reaction with their environment [1,2,3]. Corrosion damage has been a major economic and industrial problem necessitating research into solutions to mitigate it. Structural damage and damages to equipment and components made of metals and alloys is prevalent in construction plants, petrochemical refining, mining of ores, fertilizer production, energy generation etc. Leading to flow interruptions, toxic leakages, plant shutdowns, industrials downtime, and high cost of repair and maintenance due to corrosion [6]. A report in 2000 showed that approximately 3.1% of U.S total GDP was spent on corrosion repairs, maintenance and prevention [7]. Mitigating the adverse effect of corrosion involves reducing material losses resulting from the corrosion of metallic parts by the most effective and economical method, and sustaining safety of operating equipment which may fail, collapse or breakdown due to corrosion such as in pressure vessels and boilers [8].
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