Corrosion polarization behaviour and inhibition of S40977 stainless steel in benzosulfonazole/3Â M H2SO4 solution

Benzosulfonazole was evaluated for its corrosion inhibition effect on S40977 stainless steel in 3 M H2SO4 solution through potentiodynamic polarization, open circuit potential measurement, optical microscopy and IR spectroscopy. Results obtained showed the effective performance of the compound with values of 77.33%-88.32% inhibition efficiency, at 0.25%-1.25% inhibitor concentration from electrochemical analysis. Corrosion potential value decreased from −0.359 V to −0.306 V upon addition of the compound at 0.25% concentration, which decreased progressively to −0.278 at 1.25% concentration. Identified functional groups of alcohols, phenols, amines, amides, carboxylic acids, aliphatic amines, esters and ethers within the compound completely adsorbed onto the steel from analysis of the adsorption spectra while others decreased in intensity due to partial adsorption. Thermodynamic calculations showed the cationic adsorption to be through chemisorption mechanism according to Langmuir, Freundlich and Temkin adsorption isotherms. Micro-analytical images showed a severely corroded morphology with corrosion pits in the absence of benzosulfonazole which contrast the images obtained with the inhibitor addition. The compound was determined to be mixed type inhibition.