Synergistic inhibition of aluminium corrosion in H₂SO₄ solution by polypropylene glycol in the presence of iodide ions

Abstract

Purpose The purpose of this paper is to evaluate the performance of polypropylene glycol (PPG), as a corrosion inhibitor for aluminium corrosion in 0.5 M H2SO4 solution at 303-333 K and the effect of addition of iodide ions on the corrosion inhibition efficacy of PPG. Design/methodology/approach The corrosion inhibition performance of PPG alone and on addition of iodide ions in the acid medium was evaluated using weight loss and electrochemical [electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and potentiodynamic polarization (PDP)] methods as well as surface analysis approach at 303-333 K. The morphology of the corroding aluminium surface without and with the additives was visualised using scanning electron microscopy (SEM). The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption. Findings Results obtained showed that PPG moderately retarded the corrosion of Al in 0.5 M H2SO4 solution. Addition of KI to PPG is found to synergistically improve the inhibitive ability of PPG. From the variation of inhibition efficiency, K_ads, and E_a, with rise in temperature, physisorption mechanism is proposed for the adsorption of PPG and PPG + KI onto the Al surface in 0.5 M H2SO4 solution. Polarisation results showed that PPG and PPG + KI acted as mixed type inhibitor. The adsorption of PPG and PPG + KI, respectively, onto the metal surface followed El-Awady et al. adsorption isotherm model. SEM and water contact angle analysis confirmed the adsorption of PPG and PPG + KI on Al surface. Research limitations/implications The research is limited to aqueous acid environment in aerated condition, and all tests were performed under static conditions. Practical implications The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal. Originality/value The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

Experimental and Quantum Chemical Evaluation of 8-Hydroxyquinoline as a Corrosion Inhibitor for Copper in 0.1 M HCl

“…EIS is a powerful tool that has been used to gain insight into metal corrosion and adsorption phenomena. ,, EIS experiments were conducted to have a clearer picture of the corrosion and corrosion inhibition of Cu in 0.1 M HCl in the absence and presence of 8-HQ. Figure shows the EIS plots obtained for this system in (a) Nyguist, (b) Bode modulus, and (c) phase angle representations.…”

“…For this reason, the values of θ were fitted into the El-Awady kinetic/thermodynamic adsorption model, which is a modification of the Langmuir isotherm and takes into consideration the omitted interaction parameter by the Langmuir isotherm. Equation gives the description of the El-Awady kinetic/thermodynamic adsorption model. K ads is equal to K 1/ y . 1/ y represents the number of active sites occupied by an inhibitor molecule or the number of water molecules replaced by an inhibitor molecule .…”

“…For this reason, the values of θ were fitted into the El-Awady kinetic/thermodynamic adsorption model, which is a modification of the Langmuir isotherm and takes into consideration the omitted interaction parameter by the Langmuir isotherm. Equation 14 31 gives the description of the El-Awady kinetic/thermodynamic adsorption model.…”

Synergistic effect of halide ions and gum arabic for the corrosion inhibition of API5L X70 pipeline steel in H2SO4

“…Plots of C/θ with C at 30 °C yield straight line with slope values close to 1. From the values of the adsorption constant, Kads, the standard free energy of adsorption ΔG° ads is determined using the following equation: where 1 × 10 6 is the concentration of water molecules expressed in mg L −1 , R is the universal gas constant and T is the absolute temperature. The values of ΔG° ads and K ads are listed in Table .…”

Bark resin of Schinus molle as an eco‐friendly inhibitor for API 5L X70 pipeline steel in HCl medium

“…By plotting C / θ versus C , straight line with slope value close to 1 was obtained. From the value of the adsorption constant, the standard free energy of adsorption is determined using the following equation: where 1 × 10 6 is the concentration of water molecules expressed in mg L −1 , R is the universal gas constant and T is the absolute temperature. The values of and K ads are listed in Table .…”