Experimental, computational, and theoretical studies on the corrosion inhibition potential of green Gongronema latifolium extract as corrosion inhibitor for aluminum alloy in HCl solutions

Abstract

Gongronema latifolium (GL) leaves extract was studied as a potential corrosion inhibitor for AA3003 aluminum alloy immersed in 0.4, 0.75 and 1.10 M HCl solution at 302–322 K. Herein, gravimetric, thermometric, electrochemical techniques, density functional theory via DFT/molecular dynamics simulation (MDS), scanning electron microscope (SEM)/X-ray diffraction analysis (XRD) were employed to analyze the effect of GL leaves extract on AA3003 aluminum alloy corrosion. Excellent statistical and machine learning techniques such as the response surface methodology (RSM) and artificial neural network (ANN) were used for the optimization and modeling. The constituent compounds of the GL leaves extract and their chemical structures were identified using a standard approach like the gas chromatography-mass spectrometry (GC–MS). The GL leaves extract significantly retards AA3003 aluminum alloy corrosion and its efficacy was seen to increase with increase in the GL leaves concentration in the acid media. Maximum inhibition efficiency (IE%) of 84.15 %, 81.45 %, 86.83 % and 87.11 %, were obtained for the mass loss, thermometric, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) methods, respectively in 0.75 M HCl solution at 312 K and 1.3 g/L GL leaves extract concentration. The RSM recorded highest IE% of 81.30 % in 0.75 M HCl, 1.30 g/L GL leaves extract concentration, temperature of 312 K and immersion time of 12 h. The ANN and ANN-GA algorithm predicted optimum IE% of 84.5160 % and 88.4189 %, respectively in 0.75 M HCl solution, 1.3 g/L GL leaves extract concentration, temperature of 312 K and 12 h immersion time. SEM/XRD examination validated the adsorption of GL leaves extracts molecules onto the A3003 metal alloy surface. The results of GC–MS analysis established that GL leaves extract comprised of compounds possessing active molecules and functional groups responsible for the corrosion inhibition of the AA3003 aluminum alloy surface in HCl media. Electrochemical investigation revealed that the inhibitor functioned as mixed-type inhibitor. The statistical and theoretical analysis results correlated with experimental results and confirmed GL leaves extract as efficient corrosion inhibitor for AA3003 aluminum alloy submerged in HCl solution.