Experimental Study and Response Surface Methodology of Azo Dye as an Eco-Friendly Corrosion Inhibitor for Stainless Steel in a Chloride Solution

DAD was investigated as CI for SS corrosion in a 3.5% NaCl solution, using WL, thermometric and RSM techniques. The analyses results show that IE(%) of DAD was dependent on its Ct and T. The highest IE(%) values were recorded on 5.0 g/L, at 303 K, by thermometric and WL methods (90.0 and 98%, respectively). DAD adsorption onto the SS surface was found to be spontaneous, obeyed Langmuir's isotherm, and its mechanism appeared to be partly physical, partly chemical. The results of RSM techniques supported experimental data. Finally, SEM was used to examine SS surfaces morphology without and with DAD, and its results confirmed the CI process.