Effect of meat extract as an eco-friendly inhibitor on corrosion behavior of mild steel: Electrochemical noise analysis based on shot noise and stochastic theory

Abstract

The present work aimed to investigate the corrosion behavior of mild steel in hydrochloric acid solution in the presence of meat extract as an eco-friendly inhibitor using weight-loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscope. Besides, in order to evaluate the inhibitive performance of meat extract for pitting corrosion of mild steel, electrochemical noise (EN) analysis was used. It was revealed that about 94% of the mild steel surface was covered by meat extract molecules, and the corrosion rate was reduced around 6-fold (from 65 to 11 mpy) comparing to the sample exposed to blank solution. A good trend was observed between the EN data and the results obtained from the other techniques. Based on shot noise theory, introducing meat extract up to 500 ppm into the solution shifts the cumulative probability of the corrosion events on the steel surface to higher frequencies, which is a sign of less localized corrosion. Stochastic modeling indicated that the presence of meat extract inhibitor leads to both a fall in the pit initiation rate and a decrease in the propagation probabilities of the metastable pits. Combining these with the SEM/EDS results revealed that the meat extract by the formation of an adsorption film on the steel surface results in the enhancement of the pitting corrosion resistance.