Evaluation of pawpaw leaves extract as anti-corrosion agent for aluminium in hydrochloric acid medium

Pawpaw leaves extract was examined as anti-corrosion agent for aluminium in hydrochloric acid medium. The extract and corrosion product were analyzed using Fourier transform infrared spectrophotometer (FTIR). Thermometric, gravimetric, potentiodynamic polarization and scanning electron microscopic methods were employed in the study. The inhibition efficiency was optimized using Response Surface Methodology (RSM) of Design Expert Software 9. Inhibitor concentration (0.2 g/l – 1.0 g/l), temperature (303 K – 333 K) and time (1hour - 5 hours) were the considered factors. It was revealed that stretched C-H and O-H functional groups were predominantly responsible for the corrosion inhibition process. The adsorption of the extract on the aluminium surface adhered to the mechanism of physical adsorption. A quadratic model adequately described the inhibition process. Optimum inhibition efficiency of 80.58% was obtained at inhibitor concentration of 0.961 g/l, temperature of 311.459 K and time of 3.932 hrs. The extract is a mixed-type inhibitor that can control both cathodic and anodic corrosion.Keywords: Aluminium, Anti-Corrosion, HCl, Pawpaw Leaves

Optimization and electrochemical study on the control of mild steel corrosion in hydrochloric acid solution with bitter kola leaf extract as inhibitor

Response surface methodology was applied to predict the optimum control of mild steel corrosion in acid medium with bitter kola leaf extract as inhibitor. The experiment was carried out to investigate the mutual interactions between the considered independent variables and the expected responses. Thermometric, gravimetric, potentiodynamics polarization and electrochemical impedance spectroscopy were used in the corrosion inhibition study. As a supplementary technique, infrared spectroscopy was used to analyze the pure extract and corrosion products and it was observed that some peaks shifted while some disappeared. Inhibition efficiencies of 88.24 %, 86.81 %, 90 %, 89.5 % and 85.3 % were obtained from optimization, thermometric, gravimetric, potentiodynamics polarization and electrochemical impedance spectroscopic techniques, respectively. The bitter kola leaf extract behaved as a mixed-mode inhibitor. Application of response surface methodology in this study was found to be good in predicting the optimum range for controlling of metal corrosion thereby reducing the number of experimental runs.Keywords: Acid, bitter kola leaf, Fourier transform infrared, mild steel, electrochemical impedance spectroscopy, potentio dynamics polarizatio

PORTUGALIAE ELECTROCHIMICA ACTA Modeling the Corrosion Inhibition of Mild Steel in HCl Medium with the Inhibitor of Pawpaw Leaves Extract

Abstract Modeling the corrosion inhibition of mild steel in HCl medium with inhibitor of pawpaw leaves extract is presented. The extract was analyzed using gas chromatography-mass spectrometry. Thermometric and gravimetric methods were employed in the corrosion inhibition study. The inhibition efficiency was modeled and optimized using response surface methodology (RSM). It was observed that the free energy of adsorption (∆G ads ) was negative and less than the threshold value of -40 kJ/mol. The adsorption of the extract was spontaneous, and occurred according to the mechanism of physical adsorption. A quadratic model was generated, with optimum inhibition efficiency of 80.29% obtained. The extract was highly efficient in the corrosion control process. It is effective for surface treatment of mild steel in the acid medium. Therefore, it is recommended that pawpaw leaves extract should be employed as corrosion inhibitor in oil well acidizing and surface treatment of mild steel

Deployment of Antepsin (Sucralfate) as Corrosion Inhibitor of Mild Steel in H2SO4 Medium: Chemical and Electrochemical Studies

This study presents the deployment of antepsin (sucralfate) as corrosion inhibitor of mild steel in H2SO4 medium. Chemical (gravimetric) and electrochemical (potentiodynamic polarization and electrochemical impedance spectroscopy) techniques were used in the corrosion control investigation. The antepsin drug was characterized by gas chromatography mass spectrophotometer (GCMS) and Fourier transform infrared (FTIR) spectroscopy. Effects of inhibitor concentration, temperature and time on weight loss, corrosion rate, inhibition efficiency and degree of surface coverage were examined. Thermodynamic and adsorption properties of the corrosion inhibition process were determined. Inhibition efficiency was optimized using central composite design tool of Design Expert software version 12. Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to determine the type and effectiveness of the inhibitor. As a confirmatory test, scanning electron microscopy (SEM) was employed to examine the surface morphology of the mild steel samples. Analysis of the results showed that major constituents of antepsin include tetradecanoate, metronidazole, hexadecanoic acid, methyl ester and 11-octadecenoic acid. The predominant functional groups include; C=O stretch, C-H bend and symmetric and asymmetric =C-O-C. Adsorption of the molecules of antepsin on the surface of the mild steel was spontaneous and occurred in agreement with physical adsorption. A quadratic model adequately described the relationship between inhibition efficiency and corrosion control variables of concentration of the inhibitor, temperature and time. Optimum inhibition efficiency of antepsin was obtained as 86.75%. Chemical and electrochemical results agreed that antepsin is suitable for corrosion control of mild steel in H2SO4 solution. Antepsin acted as mixed-type inhibitor (controlled both cathodic and anodic reactions)

Optimization of corrosion inhibition of Picralima nitida leaves extract as green corrosion inhibitor for zinc in 1.0 M HCl

Herein, the optimization of inhibitive action of the ethanol extract of oil from Picralima nitida leaves, towards acid corrosion of zinc, was tested using weight loss and thermometry methods. We found that the extract acts as a good corrosion inhibitor for zinc corrosion in 0.1 M HCl solutions. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. This revealed that spontaneous processes govern the adsorption of the extract on zinc surface. Herein, the inhibition efficiency (IE) increases in line with corresponding increase in extract concentration. The temperature effect of the corrosion inhibition on the IE was also studied. This indicated that the presence of the extract increases the needed activation energy of the corrosion reaction. Furthermore, in our work, an optimal inhibition efficiency IE (%) of 86.78 was obtained at optimum inhibitor concentration of 1.2 gl-1, optimum temperature and time of 313 k and 8 hrs, respectively. From the calculated thermodynamic parameters, it can be said, then, that Picralima nitida extract provides good protection to zinc against pitting corrosion in chloride ion containing solutions