Corrosion Inhibition Of Mild Steel In 1 M Hcl Solution By Curcuma Longa Rhizome Extract
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Date
2013-11
Authors
Khairi, Nurul Izni
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The inhibitive action of the extract of Curcuma longa or generally known as turmeric
for mild steel corrosion inhibitor in 1 M HCl solution was investigated. The effect of
nine solvent systems (based on polarity) on the solubility of Curcuma longa has been
studied. It was revealed that the Curcuma longa extracted with 95% aqueous ethanol
gave the highest solubility and extraction yield. Characterization studies have been
conducted to determine the curcumin content which is the active ingredient. Fourier
transform infrared (FTIR) spectroscopy results suggest the presence of important
functional groups that can fulfil the requirement as a potent organic corrosion
inhibitor. The experimental findings based on the maximum absorption (λmax) of the
Curcuma longa extract from the UV-Visible (UV-Vis) spectroscopy gives strong
evidence on the presence of curcumin. The analysis of curcuminoids by means of
reversed phase liquid chromatography mass spectrometry (LCMS) using C18 column
have shown that curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin
(BDMC) were separated. The effect of Curcuma longa extract and standard
curcumin as reference were investigated as corrosion inhibitors for mild steel in
acidic media. The Curcuma longa extract exhibited 70% corrosion inhibition
efficiency at 80 ppm concentration. Potentiodynamic polarization measurement
revealed that the inhibitors behave as mixed type inhibitor, promoting retardation of
both anodic and cathodic reactions. The electrochemical impedance spectroscopy
(EIS) revealed that the charge transfer was the main controlling factor of the
corrosion reaction. From the potential of zero charge (PZC) measurement, the
negatively charged metal surface might be responsible for the electrostatic adsorption
of the protonated molecules.
Description
Keywords
Corrosion Inhibition , Mild Steel In 1 M Hcl Solution