Inhibition properties of Vang tea-water extract for carbon steel corrosion in acidic environments

Abstract

BackgroundMetallic corrosion saps the economy, pollutes the environment, and affects human health and life due to the related toxic chemicals, unwanted reactions, and project collapse, as well as contaminative products. The use of corrosion inhibitors could be a great help to reduce corrosion of metallic materials in severe working conditions. In recent years, natural products have been used for protecting against the corrosion of carbon steel. MethodsVang tea leaves - water extract (VTLWE) was recommended as a corrosion inhibitor with low-cost and a safe class of material for carbon steel in 1.0 M HCl, 0.5 M H2SO4, and their mixed acidic solutions. VTLWE raw materials were characterized by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and liquid chromatography-mass spectrometry (LC-MS). Electrochemical properties have been characterized by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and potentiodynamic polarization (PD). Post-immersion surface analyses were also evaluated using scanning electron microscopy (SEM), ATR-FTIR, and X-ray photoelectron spectroscopy (XPS). Significant FindingsThe electrochemical data showed that VTLWE posed as a mixed-type inhibitor with more cathodic characteristics and the inhibition effectiveness significantly depended on the VTLWE concentration that increased with an increase of VTLWE in 1.0 M HCl and 0.5 M H2SO4 solutions due to lower corrosion current density and higher polarization resistance. In addition, the results also indicated that 0.5 M H2SO4 solution was more aggressive than 1.0 M HCl solution and was subjected to a higher level of steel corrosion inhibition by VTLWE. Surface analysis results confirmed the occurrence of the organic film layer on the steel surface, assigning to the bonding of functional groups and heteroelements in VTLWE species that were available in investigated solutions. Therefore, the work could add VTLWE as new materials to inhibition systems, giving rise to the durable protection against steel corrosion and supplying inspiration in related applications.