Vanillin-derived non-ionic surfactants as green corrosion inhibitors for carbon steel in acidic environments

Abstract

Four eco-friendly ('green') non-ionic surface active agents were synthesized via reaction of fatty acids obtained from hydrolysis of castor oil with vanillin. The products were then reacted with monoethanol amine to form a vanillin ester Schiff base. The vanillin ester Schiff base was ethoxylated using ethylene oxide gas in the presence of tri-ethyl amine as a catalyst to give the desired nonionic surfactants. The chemical structures of the obtained surfactants were characterized using FTIR and 1 HNMR spectroscopy. The inhibition effect of the four synthesized non-ionic surfactants derived from vanillin (VE15, VE20, VE40, and VE60) on the corrosion of carbon steel in acidic media of 0.5-M HCl was studied by weight loss, potentiodynamic and electrochemical impedance spectroscopy measurements. The results show that the synthesized inhibitors are effective inhibitors even at very low concentrations, and the adsorption on carbon steel surface obeys the Langmuir adsorption isotherm. Potentiodynamic polarization curves reveal that the synthesized inhibitors behave as mixed-type inhibitors. Adsorption of used inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. Calculated DG ads o values indicated that the mechanism by which these inhibitors adsorb onto carbon steel in 0.5-M HCl solution is chemical adsorption. The surface activities of the synthesized surfactants were determined using surface tension measurements. The biodegradability of these surfactants indicates that the compounds readily degrade in the environment and can be considered as green corrosion inhibitors.

Mitigation of eco‐unfriendly and costly microbial induced corrosion using novel synthesized Schiff base cationic surfactants

“…Moreover, the antimicrobial action of the synthesized surfactants also depends on the presence of a quaternary group as a hydrophilic portion, which influences the adsorption of the surfactant molecules on the surface of the bacterial cell and acts by interrupting the cell membrane 33 . Cationic surfactant is known as a type of surfactant where the head part bears a positive charge and is characterized by its high efficiency as a biocide as well as a corrosion inhibitor, as it is partially or completely adsorbed at the interface (metal/liquid) and protects the metal surface from bacterial growth 34 . Thus the mode of action of that type of compound (surfactant) on various microorganisms can be related to the adsorption of surfactant molecules on the outer cell membrane of the microorganisms due to their amphipathic characteristics, as well as the similarity between the hydrophobic chain to the lipid layer and the building units of the cell membranes.…”

New Biodegradable Nonionic‐Anionic Surfactants Based on Different Fatty Alcohols as Corrosion Inhibitors for Aluminum in Acidic Medium

“…Weight loss test was carried out three times on aluminum samples coupons with surface area 1.0 cm 2 and the weight was the average of the three coupons. The samples were mechanically polished with emery paper, ultrasonically degreased in alkaline mixtures, then after washing by distilled water use filter paper to dry them and weigh them (Tewfik and Negm, 2016). The weight loss (g/cm 2 ) was measured at different immersion times at a temperature of 30 °C by calculating the weight of the samples before and after immersion into 100 mL of the test solution (1.0 M HCl with and without the inhibitors).The weight loss, the corrosion rate K and the percentage inhibition efficiency %IE was determined by using the following equations (Chen et al, 2011).…”

Triton X-100 as a Non-Ionic Surfactant for Corrosion Inhibition of Mild Steel During Acid Cleaning

“…From the weight loss data; surface coverage, inhibition efficiency and corrosion rates were calculated respectively according to Eqs. (1), (2) and (3) [23][24][25]:…”

“…The degree of surface coverage (θ) at different temperatures of the inhibitor in the solution has been concluded from the weight loss method. In the present study various adsorption isotherms were considered, namely Langmuir [23,27], Frumkin [28,29], Temkin [30,31], Freundlich [32,33] ElAwady [34,35]. Nonetheless, only Langmuir isotherm was the valid tested isotherm (vide infra).…”