The corrosion inhibition abilities of PVA and PVP against the corrosion of mild steel in hydrochloric acid

• S. Abdulhadi¹, A. Mohammed², W.K. Al-Azzawi³, T. Gaaz⁴, A.A.H. Kadhum⁵, L.M. Shaker⁶ and A.A. Al-Amiery^1,6

¹ Energy and Renewable Technology Centre, University of Technology – Iraq, Baghdad, 10001, Iraq
² Department of electromechanical engineering, University of Technology – Iraq, Baghdad, 10001, Iraq
³ Al-Farahidi University, Baghdad, 10001, Iraq
⁴ Department of Machinery Equipment Engineering Techniques, Technical College Al-Musaib, Al-Furat Al Awsat Technical University, Al-Musaib, Babil 51009, Iraq
⁵ Al-Ameed University, Karbalaa, 56001, Iraq
⁶ Department of Chemical and Process Engineering, Faculty of Engineering and Build Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor 43600, Malaysia

Abstract: Corrosion inhibitors are chemical compounds that react with the corrosive environment, forming a protective film on the surface of the metal and reducing the rate of corrosion. These inhibitors work by either neutralizing the corrosive environment, inhibiting the corrosion reaction, or both. The introduction of corrosion inhibitors in a corrosive environment aims to reduce the corrosion of well pipes, which are commonly made of mild steel. This method is a reliable and economically beneficial way to combat corrosion. The effects of polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) on the corrosion of mild steel in 1 M hydrochloric acid have been studied using gravimetric techniques and surface morphology analysis. The study investigated the impact of inhibitors concentration, immersion period, and temperature on corrosion rates and inhibition efficiencies for mild steel in HCl conditions. The results showed that PVA has a better inhibition efficiency than PVP at 303 K, with 0.5 mM PVA providing 92.1% protection compared to 0.5 mM PVP which provided 89.4% protection. The inhibition efficiency of PVA increases with increasing concentration but decreases slightly with increasing temperature, while the inhibition efficiency of PVP increases with increasing concentration and temperature. Both inhibitors follow Langmuir adsorption isotherms. Scanning electron microscopy (SEM) was used to examine the surface morphology of the untreated and treated mild steel samples, which showed that both PVA and PVP have the ability to prevent corrosion. A mechanism has been proposed to explain the inhibitory action of PVA and PVP.

Keywords: PVA, PVP, corrosion inhibitor, corrosion rate, Langmuir isotherm

Int. J. Corros. Scale Inhib., 2023, 12, no. 2, 645-663
doi: 10.17675/2305-6894-2023-12-2-14

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