An atomic emission spectroelectrochemical study of corrosion inhibition: The effect of hexamethylenetetramine on the reaction of mild steel in HCl

The dissolution of low carbon steel in hydrochloric acid has been investigated by atomic emission spectroelectrochemistry. The rate of Mn, Fe and P dissolution was measured as a function of time for steels of variable Mn and P composition and as a function of HMTA concentration. Regardless of the reactivity of the steel in uninhibited solutions, at high concentration of HMTA, all steel grades show a nearly identical dissolution rate. The effect is selective for Fe; the dissolution of segregated Mn is not affected by HMTA.

Research highlights
► Time resolved elemental dissolution rates on time scales typical for pickling lines.
► Segregated impurities dissolve selectively at early stages.
► At high HMTA concentration the dissolution rate is the same for different steels.
► Several mechanisms of HMTA inhibition are discussed.