Cyclic Potentiometric Polarization and Resistance of Mild Steel in an Environment of Alcohols and Their Blends with Gasoline

Abstract

Nowadays, there is an effort to increase the more widespread use of biofuels that are a renewable energy source in transportation and an alternative to conventional, petroleum-based fuels. These biofuels include alcohols such as biomethanol, bioethanol, and biobutanol that have a high octane number, but generally different physical and chemical properties than petroleum fuels. The different properties of alcohols may cause low material compatibility with carbon steel. Here, we used cyclic potentiodynamic polarization (CPP) to study the behavior of carbon steel in an environment of alcohols and alcohol–gasoline blends (AGBs). Using CPP, we proved that the corrosion of mild steel can be significantly influenced by alcohol properties, such as the chain length, pKa, and solubility of oxygen and water. In the environment of pure alcohols (not blended by gasoline), a very good passivation ability of steel was proven, especially for n-butanol. In AGBs, steel corrosion can also be influenced by the gasoline amount. When these pure alcohols or their gasoline blends are contaminated by water-containing chlorides and organic acids, the corrosion rate of carbon steel can increase by up to 4 orders of magnitude. In an anhydrous environment of alcohols, the CPP can give results with a very good informative value.

Electrochemical Study of Mild Steel Resistance in Butanol–Gasoline and Ethanol–Gasoline Blends

“…The applied contamination solution has already been applied in several corrosion studies of EGBs, especially for those with an ethanol content of 60 vol % and higher. ,, The content of the contaminants in these fuels with a content of 6 vol % of water then corresponds to the concentration of acetic acid, 52.5 mg L –1 ; sulfuric acid, 3.1 mg L –1 ; sodium chloride, 3.2 mg L –1 ; and sodium sulfate, 2.7 mg L –1 . In our case, the concentrations of the X85 and X100 fuels were the same.…”

“…37 In contrast, the electrochemical methods have higher requirements on the experimental equipment, but they provide instantaneous data about the ongoing corrosion process. 36 Electrochemical corrosion testing of AGBs has typically been performed using electrochemical impedance spectroscopy (EIS) in two- 23,29 or three-electrode 38 arrangements, open circuit potential (OCP), 24 cyclic potentiodynamic polarization, 25,33,34,39 and polarization characteristics measurements. 40 In this work, the mild steel corrosion resistance in EGBs and BGBs with an alcohol content of 10−100 vol % was tested.…”

Corrosion Aggressiveness of Ethanol–Gasoline and Butanol–Gasoline Blends on Steel: Application of Electrochemical Impedance Spectroscopy

“…In contrast, great attention has been paid to ethanol−gasoline blends (EGBs) and their corrosion effects on metallic materials. 16−32 These corrosion studies have mostly been performed using gravimetric 18,20,31,32 and/or electrochemical 16,17,[22][23][24][25][26][27][28][29][30]33,34 methods. Gravimetric methods are based on the evaluation of the weight change (loss) of the tested materials caused by the corrosion process.…”

Electrochemical Corrosion Tests in Low-Conductivity Ethanol–Gasoline Blends: Application of Supporting Electrolyte for Contaminated E5 and E10 Fuels

“…EIS and TS measurements in EGBs have typically been performed on fuels with a higher ethanol content, typically E85 and higher, as the conductivity of such fuels is high enough to obtain electrochemical corrosion data. ,,− Based on our own experience, we can conclude that EIS and TS measurements are generally not problematic for EGBs with an ethanol content of 40 vol % and more (E40 and higher). Overall, EIS can be performed in a two- or three-electrode arrangement, while TS can only be measured in three-electrode systems.…”

“…The gravimetric and electrochemical methods have also been used to evaluate the efficiency of corrosion inhibitors. Based on these studies, substances such as ethanolamines, diethylenetriamine, hexamethylene triamine, piperazine, morpholine, and others were found to be promising steel corrosion inhibitors in ethanol environments. − Electrochemical impedance spectroscopy (EIS) and polarization characteristics measurements (Tafel scanTS) are the most typical methods for electrochemical corrosion studies of EGBs. ,,− …”