Insight into the Adsorption and Inhibitive Effect of Spironolactone Drug on C38 Carbon Steel Corrosion in Hydrochloric A
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Insight into the Adsorption and Inhibitive Effect of Spironolactone Drug on C38 Carbon Steel Corrosion in Hydrochloric Acid Environment Ngozi J. Maduelosi1 · Nkem B. Iroha2 Received: 3 September 2020 / Revised: 13 October 2020 / Accepted: 20 October 2020 © Springer Nature Switzerland AG 2020
Abstract The inhibitive effect of spironolactone drug (SPR) on C38 carbon steel corrosion in 10% hydrochloric acid solution was investigated using weight loss and two electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), in the temperature range between 30 and 60 °C. Spironolactone was found to act as an inhibitor for the acid corrosion of C38 carbon steel. Inhibition efficiency of the drug increased with an increase in concentration of SPR but decreased with increase in temperature. The maximum inhibition efficiencies obtained with 7.2 × 10–3 M SPR at 30 °C were 98.1%, 95.0% and 95.8% for weight loss, EIS and PDP technique, respectively. Anodic and cathodic polarization curves reveal that SPR is a mixed-type inhibitor. Impedance data show that charge transfer process controlled the mechanism of corrosion. The adsorption of SPR on the C38 steel surface was found to be spontaneous and obeyed Langmuir isotherm at all studied temperatures. The adsorption is a mixed adsorption involving both chemisorption and physisorption. The carbon steel surface was assessed using scanning electron microscopy (SEM), which also revealed the protective ability of the drug for C38 carbon steel in 10% HCl solution. Quantum chemical calculations in the framework of the density functional theory were undertaken to theoretically describe the adsorption and inhibition action of SPR on the C38 steel surface. Keywords Corrosion inhibition · Spironolactone · C38 steel · Electrochemical techniques · Adsorption
1 Introduction Protection of carbon steel from corrosion is very critical due to their application in many industry particularly the power plants and petroleum industry [1]. Certain industrial activities like descaling, pickling, including oil well acidizing brings carbon steel in contact with hydrochloric acid solution, extensively used as a cleaning mixture in most industries. These activities get the metal severely corroded. Several methods have been employed to protect metals from these corrosive agents. Strategies like coating, anodic protection, cathodic protection and the use of corrosion inhibitors have been studied and recommended as good methods to combat metal corrosion. The use of corrosion inhibitors * Nkem B. Iroha [email protected]; [email protected] 1
Department of Chemistry, Rivers State University, Port Harcourt, Nigeria
Electrochemistry and Material Science Unit, Department of Chemistry, Federal University, Otuoke, Nigeria
2
have always been the most economical and effective method in reducing the undesirable carbon steel dissolution [2, 3]. Most well-known corrosion inhibitors, both natural and synthetic, are organic compounds possessing sulfur
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