Adsorption mechanism of quaternary ammonium corrosion inhibitor on carbon steel surface using ToF-SIMS and XPS

ToF-SIMS and XPS are combined to study the adsorption of tetradecyl-benzyldimethyl-ammonium (BDA-C14) bromide corrosion inhibitor on carbon steel surface. BDA-C14 forms a protective layer with N-containing polar head group interacting with carbon steel surface. The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration. A maximum and uniform coverage is found for sufficiently long exposure times at a critical inhibitor concentration of about 25 ppmw. The uniform adsorbed inhibitor layer formed on the surface mitigates the formation of iron chloride/hydroxide intermediates and thus enhances the corrosion protection of carbon steel in aggressive environment. •The adsorption of BDA-C14 corrosion inhibitor on carbon steel surface was studied by ToF-SIMS and XPS.•The inhibitor forms a protective layer with N-containing polar head group interacting with carbon steel surface.•The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration.•The critical concentration for a maximum and uniformed inhibitor coverage on carbon steel is determined.•The uniform adsorbed inhibitor layer on carbon steel can mitigate the formation of iron chloride/hydroxide intermediates.