Effect of henna and rosemary extracts on the corrosion of 304L stainless steel in 3.5% NaCl solution

Abstract

The inhibitive action of two natural compounds—henna and rosemary extracts, on the corrosion of 304L stainless steel in 3.5% NaCl solution has been investigated through electrochemical techniques and surface analysis. Polarization measurements indicate that the investigated compounds are mixed-type inhibitors, and the higher the inhibitor concentration, the higher the inhibition efficiency. Maximum inhibition efficiencies of 92.7% and 90.2% of henna and rosemary extracts are obtained at 1.0 g/L, respectively. The polarization curves show that henna and rosemary extracts act as a cathode-type and an anodic-type inhibitor, respectively. The results show that these additives in saline media are adsorptive inhibitors and their adsorption obeys the Langmuir adsorption isotherm.