4-{[4-(Dimethylamino)benzyIidene]amino}-5-methyl-4H-l,2,4-triazole-3-thiol as Corrosion Inhibitor for 316 Stainless Steel in 2.5 M Sulphuric Acid: An Experimental and Theoretical Investigation

摘要

The corrosion inhibition competence of 4-{[4-(dimethylamino)benzylidene]amino}-5-methyl-4H-l,2,4-triazole-3-thiol (DBTT) on 316 stainless steel (316 SS) in 2.5 M H2SO4 was studied using various electrochemical as well as weight-loss measurements. The alloy surface was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Concentration effect on inhibition efficiency was investigated by varying concentration from 5 to 2000 ppm in the temperature range 30-60 °C. Results indicated mixed-type inhibitory action of DBTT. The efficiency increased with the raise in concentration of DBTT and temperature, reaching a highest of 92.4 % at 60 °C. Langmuir adsorption isotherm is obeyed. Calculation of different thermodynamic factors suggests that the adsorption is via both physisorption and chemisorption. In addition to these, several global reactivity parameters were calculated using DFT method at B3LYP/6-31 l++(d,p) basis set. Theoretical calculations are in good concurrence with the experimental results.