Electrochemical studies, adsorption behavior, and spectroscopic analysis of vanadyl complex of bis(1-(pyridin-2-yl)ethylidene)malonohydrazide as efficient eco-friendly corrosion inhibitor for low carbon steel in 1M HCl

Abstract

Corrosion is a destructive attack that can effect on a substance. One of the most important problems is corrosion losses, which can cause a loss of 10% of the metallic output every year. A novel VO+2 complex of N1, N3-bis(1-(pyridin-2-yl)ethylidene)malonohydrazide [(VO)2(L)(OH)2].H2O has been prepared and utilized as corrosion controller for Low carbon steel (LCS) in hydrochloric acid solution. Chemical (Weight loss (WL)), electrochemical (electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP)) are utilized to examine the effectiveness of prepared [(VO)2(L)(OH)2].H2O (VOL). The inhibition efficacy improved with increasing the VOL doses. The maximum efficacy of the investigated inhibitor is 96.1% at 21×10−6 M. However, at 21×10−6 M, the efficacy decreased from 96.1% to 84.4% when the temperature elevated from 298 to 318 K. The adsorption of VOL on the LCS surface was used to explain the inhibition. According to the values of ∆G°ads, which ranged from 25.8 to 21.5 kJ mol−1, the adsorption of the VOL on the LCS surface is physical adsorption. Analyzing the polarization curves of synthesized inhibitors revealed that they were mixed-type inhibitors. LCS was found to be surface inhibited when coated with a thin film of inhibitors, and surface morphology was assessed by different techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) was employed to explain the nature of the interface among VOL and LCS surfaces. It was found that all of these used tests agreed with each other.