Corrosion Control of Mild Steel Material in HCl Electrolyte by a Non-Steroidal Anti-Inflammatory Drug: Electrochemical a
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HYSICOCHEMICAL PROBLEMS OF MATERIALS PROTECTION
Corrosion Control of Mild Steel Material in HCl Electrolyte by a Non-Steroidal Anti-Inflammatory Drug: Electrochemical and Kinetic Study Azeddine Addouna, b, *, **, Mohamed Traric, and Ouassila Ferroukhib aFaculty
of Sciences, University of Algiers 1 Benyoucef Benkhedda, Algiers, 16002 Algeria Laboratory of Chromatography, Faculty of Chemistry, USTHB, BP 32 El Alia, Algiers, 16111 Algeria c Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32 El Alia, Algiers, 16111 Algeria *e-mail: [email protected]; **e-mail: [email protected]
b
Received July 11, 2019; revised July 19, 2019; accepted March 15, 2020
Abstract—The corrosion inhibition of mild steel by a drug substance, namely piroxicam, in HCl (1 M) solution was investigated. The Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique were used. EIS measurements showed larger capacitive loops in the presence of piroxicam. The inhibition efficiency was found to be dependent on the piroxicam concentration. From the polarization curves the corrosion current density (icor ) decreased from 109.4 to 16.93 μA/cm2. The adsorption mode of the drug obeys to the Langmuir isotherm model. The free energy of adsorption (∆Gads) revealed a spontaneous process with a mixed interaction type i.e. physical and chemical. The kinetic study was conducted using the weight loss technique at the optimal piroxicam concentration (600 ppm). The density functional theory (DFT) method was used to determine the principal species, neutral or ionized drug, involved the inhibition mechanism. Scanning electron microscopy (SEM) was carried out for the surface characterization of the carbon steel after immersion in the aggressive medium in the absence and presence of the drug substance. Keywords: EIS, corrosion, adsorption, DFT DOI: 10.1134/S2070205120040024
1. INTRODUCTION Modern societies are facing environmental and economic challenges caused by the corrosion of the metallic structures. The registered loss is estimated to cost about 1 to 5% of the gross national product (GNP) of many countries [1]. Corrosion is recognized as an undesirable electrochemical reaction that occurs between the metal and its environment. The longer the material is exposed to the environment, the greater its degradation will be. Therefore development of protective techniques was strongly developed and is currently of great importance to reduce the corrosion cost [2– 5]. Among methods, the application of organic compounds as corrosion inhibitors has gained a great interest in various sectors [6–8]. The success of this protective technique is attributed to its efficiency, feasibility, low cost and weak toxicity [9–11]. Pharmaceutical agents have proved their effectiveness with a remarkable potential as corrosion inhibitors [12]. The protection of the metal is attributed to the adsorption of the drug molecules onto the surface which generates a protective barrier film [13]. Indeed,
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