Novel Bromide–Cucurbit[7]Uril Supramolecular Ionic Liquid as a Green Corrosion Inhibitor for the Oil and Gas Industry

Abstract

Metal corrosion is the largest problem in the oil and gas industry. Therefore, providing metallic materials with corrosion protection is an urgent task in modern research. The use of green corrosion inhibitors for corrosion protection is very important both ecologically and economically. This work is the first to introduce a novel bromide–cucurbit[7]uril (BrCU) supramolecular ionic liquid as an excellent corrosion inhibitor for the oil and gas industry. Its inhibition behaviour for carbon steel in 1 M NaCl saturated with CO2 and H2S was first fully identified through the use of thermodynamic and gravimetric analysis, electrochemical noise (EN), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), density functional theory (DFT), scanning electron microscopy (SEM) and energy dispersive X–ray spectroscopy (EDX) methods. The experimental results confirmed that BrCU is an excellent environmentally friendly corrosion inhibitor for the gas and oil industry. Its inhibition efficiency was 97.54% at 100 mg/L/0.06 mM, and it was more stable at high temperature (333 K). A Langmuir isotherm was applied to identify the adsorption character of BrCU on the metal surface. The obtained PDP data suggested that BrCU was a predominantly anodic mixed–type corrosion inhibitor. Theoretical calculations showed good correlation with the experimental results, indicating that the halogen modification in the supramolecular ionic liquid system improved the inhibition performance.