Effective Inhibition of Carbon Steel Corrosion by Waterborne Polyurethane Based on N-tert-Butyl Diethanolamine in 2M HCl: Experimental and Computational Findings

Abstract

The efficiency of corrosion inhibition for waterborne polyurethane based on N-tert-butyl diethanolamine (tB-WPU) is investigated using different techniques. Corrosion weight loss, open circuit potential experiments, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements show that both a commercial reagent and a polyurethane-based inhibitor prevent corrosion at increasing temperature to 50 °C. At 75 °C, the activity of both reagents is reduced. In stirring conditions, the effectiveness of acid corrosion inhibition (25 °C, 500 ppm) drops abruptly from 89.5% to 60.7%, which is related presumably to the complexity of binding the polymer molecules to the metal surface. As follows from thermodynamic calculations, the adsorption of tB-WPU on the metal surface in 2M HCl can be treated as a physisorption. Model quantum–chemical calculations support the experimental studies and elucidate the nature of steel surface–inhibitor molecule chemical bond, which is realized mainly by carboxyl and amino groups. It is concluded that WPUs can be considered as a perspective alternative to commercial oilfield reagents due to their versatility.

Effect of Chitosan on the Corrosion Inhibition for Aluminium Alloy in H2SO4 Medium

“…The presence of these elements which are adsorbed on metal surfaces, results in corrosion being inhibited, for more details can be seen in Table 5. This study is in accordance with previous studies [11][12][13][14][15][16][17].…”

“…The chitosan inhibitors adsorbed on the metal surface containing polar atoms, such as O, N, and S, can form a protective layer, and under certain conditions, the metal can undergo a passivation process or form an oxide layer [14,15]. Al 2 O 3 on the metal surface leads to a decrease in the corrosion rate [16,17].…”

“…Overall, the corrosion rate gradually increased with increasing temperature. The activation energy (E a ) of the particles increased with increasing temperature; consequently, the corrosion reaction became faster [16,17]. Furthermore, the highest efficiency of chitosan was observed at 95.12% at 298 K and then gradually decreased with increasing temperature.…”

“…Unfortunately, this inhibitor has a negative impact on the environment due to its toxicity [8][9][10][11][12][13][14]. Based on these facts, green organic inhibitors are the best alternatives that can prevent and reduce corrosion [15,16]. Chitosan is an organic compound derived from chitin; it has the potential to serve as a corrosion inhibitor, because it fulfills all the requirements.…”

“…Chitosan can be produced from chitin through hydrolysis and deacetylation processes that involve amino (-NH2) and hydroxyl (-OH) groups, both of which act as absorbents to reduce the corrosion rate through the absorption process [11][12][13][14]. Chitosan is not soluble in water but soluble in acid acetate and easily degraded, it can be utilized as a basic material in industries, health applications and as a corrosion inhibitor [11][12][13][14][15][16].…”