Influence of Mefenamic Acid on the Behavior of Stainless Steel 316 in 6% H2O2 and Normal Saline: An Electrochemical and Computational Study

Abstract

The study investigated the effects of mefenamic acid (MA) on the behavior of stainless steel 316 when immersed in three environments: a 2:1 mixture of hydrogen peroxide and normal saline (2H:1S), normal saline (S), and a 50:50 mixture of hydrogen peroxide and normal saline (SH). The corrosion potential exhibited a minor positive shift of less than 85 mV, indicating that the inhibitor operates as a mixed-type inhibitor, effectively reducing both anodic and cathodic reactions. The corrosion current density (Icorr) decreased significantly from 1775.7 µA/cm² to 123 µA/cm² in the 2H:1S, resulting in an inhibition efficiency (IE) of 93.1%. The Icorr values in S and SH solutions fell to 311 µA/cm² and 262 µA/cm², respectively, corresponding to inhibition efficiencies of 82.5% and 85.2%. The findings from electrochemical impedance spectroscopy indicated that in the 2H:1S, the charge transfer resistance (Rct) increased from 708.40 Ω·cm² in the absence of MA to 11070 Ω·cm² for the inhibited system, demonstrating an IE of 93.6%. In the S and SH solutions, Rct values exhibited significant elevations, ascending to 4100 Ω·cm² and 4500 Ω·cm², respectively. Computational analysis revealed that MA is likely to show greater electronic stabilization and heightened electrophilic character in water, resulting in enhanced reactivity.