Abstract The corrosion and inhibition processes of cold rolled steel was investigated by gravimetric weight loss measurement in 1 M HCl solution, at a temperature range of 303–333 K, in the absence and presence of potassium iodide (KI) inorganic halide salt (8.67 × 10–3–2.17 × 10–2 M), formaldehyde (FA: CH2O) organic surfactant (1.00 × 10–3 M), and KI (2.17 × 10–2 M)–FA (1.00 × 10–3 M) inhibitors mixture. The exposed surfaces of steel samples were inspected by scanning electron microscopy (SEM) and Raman micro-spectroscopy techniques. The inhibition efficiency (IE(%)) increased with KI concentration and temperature suggesting that the KI inhibitor efficiencies are temperature-dependent. The adsorption of KI on steel surface was found to obey Langmuir isotherm. The calculated adsorption free energy (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11124_2025_10099_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="45" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Delta G_{{{\text{ads}}}}^{^\circ }\)</EquationSource>  </InlineEquation>) is included between ‒20 and −40 kJ mol–1 indicating that the adsorption of KI inhibitor is a combination of both physisorption and chemisorption. It was also found that the FA inhibitor efficiency decreased with the increase of temperature, and the calculated value of activation energy (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11124_2025_10099_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({{E}_{{\text{a}}}}\)</EquationSource>  </InlineEquation>) demonstrated that the mechanism of FA adsorption is physical adsorption. It was further observed that there is a synergism for FA mixing with KI, and all calculated synergism parameters are high than unity for the entire temperature range studied. It more showed that SEM and Raman microanalyses confirmed the adsorption mechanisms of KI, FA, and FA + KI on the steel surfaces. Therefore, the more probable mechanisms of corrosion inhibition were proposed.

Gravimetric Evaluation of the Synergistic Effect between Potassium Iodide and Formaldehyde on Corrosion Failure Inhibition of Cold Rolled Steel in 1 M Hydrochloric Acid

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2025年6月1日

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Choukri Lekbir,
Feyrouz Trad,
Aicha Ziouche,
Ahmed Heddad,
Mohamed Lamine Nait Bouda,
Mourad Azibi

摘要

Abstract

The corrosion and inhibition processes of cold rolled steel was investigated by gravimetric weight loss measurement in 1 M HCl solution, at a temperature range of 303–333 K, in the absence and presence of potassium iodide (KI) inorganic halide salt (8.67 × 10^–3–2.17 × 10^–2 M), formaldehyde (FA: CH₂O) organic surfactant (1.00 × 10^–3 M), and KI (2.17 × 10^–2 M)–FA (1.00 × 10^–3 M) inhibitors mixture. The exposed surfaces of steel samples were inspected by scanning electron microscopy (SEM) and Raman micro-spectroscopy techniques. The inhibition efficiency (IE(%)) increased with KI concentration and temperature suggesting that the KI inhibitor efficiencies are temperature-dependent. The adsorption of KI on steel surface was found to obey Langmuir isotherm. The calculated adsorption free energy ( \(\Delta G_{{{\text{ads}}}}^{^\circ }\) ) is included between ‒20 and −40 kJ mol^–1 indicating that the adsorption of KI inhibitor is a combination of both physisorption and chemisorption. It was also found that the FA inhibitor efficiency decreased with the increase of temperature, and the calculated value of activation energy ( \({{E}_{{\text{a}}}}\) ) demonstrated that the mechanism of FA adsorption is physical adsorption. It was further observed that there is a synergism for FA mixing with KI, and all calculated synergism parameters are high than unity for the entire temperature range studied. It more showed that SEM and Raman microanalyses confirmed the adsorption mechanisms of KI, FA, and FA + KI on the steel surfaces. Therefore, the more probable mechanisms of corrosion inhibition were proposed.