Electrochemical, Thermodynamic, Surface, and Spectroscopic Study in Inhibition of Iron Corrosion with Turmeric Root Extract (TRE)

Khuloud Almzarzie,Ayman Almassri,Ahmad Falah,Hassan Kellawi

doi:10.5772/intechopen.92648

Abstract

Turmeric root extract was tested as corrosion inhibitor for iron in 0.5 M HCl, using potentiodynamic polarization and electrochemical impedance spectroscopy, scanning electron microscope, and energy dispersive X-ray analysis. The inhibition efficiency increases as the time of immersion rises but decreases with temperature rise. The Nyquist plots showed that the charge transfer resistance increases and the double-layer capacitance decreases as the time of immersion increases. Tafel results show that both corrosion current and corrosion speed are reduced with time of immersion. All impedance spectra of EIS tests exhibit one capacitive loop, which indicates that the corrosion reaction is controlled by charge transfer process. Inhibition efficiency increases with the concentration of the inhibitor reaching its maximum value, 88.90%, at 8 g/100 mL. Thermodynamic parameters, Ea, ∆H*, and ∆S*, were estimated, and the mechanism of corrosion and inhibition was discussed. The adsorption of turmeric root extract followed Langmuir adsorption isotherm.

Highlights

Inhibition of corrosion of iron is important for theoretical and practical aspects [1]
Turmeric root extract (TRE) used here as a corrosion inhibitor can serve as a scale inhibitor as well
Active compounds in turmeric root extract are attributed to curcumin, demethoxycurcumin, and bisdemethoxycurcumin and to the multiple lone pair of electrons, multiple bonds, and/or conjugated л-type bond system [15]

Summary

Introduction

Inhibition of corrosion of iron is important for theoretical and practical aspects [1]. Iron and its alloys are of great importance in the industry, prompting vast research on corrosion resistance and its conducts [2]. Oxygen, and nitrogen atoms are effective as corrosion inhibitors in acid media; inhibitors are used to reduce the rate of dissolution of metals [4]. Natural plant inhibitors that contain organic compounds are widely used to inhibit minerals in an acidic medium [5] and are called environmentally friendly nontoxic inhibitors [6]. The adsorption of these compounds is influenced by the electronic structure of their content of active compounds, electrons density, aromatic rings, and functional

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