Synergistic effect of the bromide and chloride ion on the inhibition of quaternary ammonium salts in haloid acid, corrosion inhibition of carbon steel measured by weight loss

Four quaternary quinolinium inhibitors were synthesized and characterized to investigate the synergistic effect of bromide or chloride anion for protecting the steel in acid corrosive medium. The inhibition was studied through gravimetric method in 4.410 M HCl and 4.410 M HBr and the results were confirmed by molecular dynamics stimulation. It is confirmed that Br- exhibits a better synergistic effect than Cl- and therefore the cationic inhibitor is much easier to get saturate adsorbed to show a better inhibition in HBr. Inhibitors with the same cation moiety can be fastened tightly and thus be able to experience chemisorption in HBr, while physisorption is the dominating mechanism in HCl.