Inhibitory Effect of Ethanolic Extract of Propolis on Corrosion of Ferritic Stainless Steel in Chloride Media

Luiza Marilac Pereira Dolabella,Tulio Matencio,Vanessa Lins,Thalys Eduardo dos Santos,Wander Luiz Vasconcelos

doi:10.15255/cabeq.2018.1559

Abstract

This work evaluates the inhibitory effect of ethanolic extract of propolis (EEP) on the corrosion of AISI 409 stainless steel (SS) in chloride media. Additions of 100, 200, and 500 μL of EEP in an aqueous sodium chloride solution were performed. The inhibitory effect on the SS was evaluated using electrochemical impedance spectroscopy (EIS) measurements up to 720 hours in immersion. EEP additions of 200 μL and 500 μL increased the polarization resistance of the SS. After 720 hours of immersion, the highest impedance was identified for the SS in solution with 500 μL of EEP. The maximum inhibition efficiency observed for addition of 500 μL of EEP in solution was 98.1 %, after 360 h of immersion.

Highlights

Corrosion inhibitors are chemical agents that reduce or prevent corrosion reactions between the metal and the environment[1,2,3,4,5]
The iron content in solution and in corrosion products released from the steel was analyzed by atomic absorption spectrometry (AAS) after 720 h of immersion to determine the global inhibition efficiency of ethanolic extract of propolis (EEP)
A different process was observed for steel in 500 μL EEP solution; inhibition efficiency remained practically constant over time because of EEP’s great effectiveness acting as a corrosion inhibitor on AISI 409 stainless steel (SS)

Summary

Introduction

Corrosion inhibitors are chemical agents that reduce or prevent corrosion reactions between the metal and the environment[1,2,3,4,5]. There are a few reports related to the bio-product inhibitor activity produced by insects, especially bees[2,9]. Research related to the inhibitory effect of ethanolic extract of propolis in solution are quite recent[4,9]. This work evaluates the potential of the ethanolic extract of propolis (EES) acting as a corrosion inhibitor on the surface of AISI 409 SS in aqueous chloride media. The selection of AISI 409 SS is that despite being a stainless steel, it has a low cost due to the low chromium content (10.5 wt.%), and a lower corrosion resistance than austenitic steels and most ferritic steels, especially in media containing chlorides, due to the low chromium content and the absence of molybdenum and nickel in its composition

Materials and methods

Results and discussion

Conclusions