Development and application of a passion fruit seed oil microemulsion as corrosion inhibitor of P110 carbon steel in CO 2-saturated brine

One of the most important causes of corrosion in the oil industry is CO2 and the injection of corrosion inhibitors is an economical way to prevent it. Recently, many efforts have been made to develop eco friendly corrosion inhibitors. This work reports the development of ecological microemulsified systems based on passion fruit seed oil applied as corrosion inhibitors for carbon steel pipes P110 in synthetic brine saturated with CO2, at different temperatures and inhibitor concentrations. The inhibition efficiency was investigated by tests of weight loss, linear polarization resistance, electrochemical impedance spectroscopy and polarization curves. The gravimetric measurements showed maximum efficiency of 975 %. The results of the electrochemical tests presented the same trends: increased inhibition efficiency at higher microemulsion concentration and lower efficiency with higher temperature. Based on Electrochemical parameters of polarization tests, the corrosion inhibition efficiency of the microemulsion M8 exceeded 99 % and the presence of the microemulsion promoted a reduction of the anodic and cathodic reactions involved in the corrosion process, characterizing the microemulsion as an adsorption inhibitor. The study of the metal surface morphology by scanning electron microscopy and contact angle measurement confirmed the ability of the microemulsion to form a film to protect the metal against attack by electrolytes. © 2020 Elsevier B.V.