Inhibition performance of 4-mercaptopyridine toward the corrosion of carbon steel in hydrochloric acid solution

The corrosion inhibition performance of 4-mercaptopyridine (4MP) as corrosion inhibitor for A3 steel has been studied using electrochemical method. The maximum inhibition efficiency value is 96.3% at 0.25 h and the inhibition efficiency is higher than 89.4% after immersion of the electrode in hydrochloric acid solution for 33 h. XPS results and frontier orbital calculation results show 4MP molecule adsorb on steel surface mainly through sulfhydryl groups and N atoms. Molecular dynamic simulation results show that an inhibitor layer formed on metal surface in the beginning while the inhibitor film changes from monolayer type to bilayer type with the increasing of time, the corrosion resistance and the corrosion inhibition efficiency of the adsorbed inhibitor film was improved. The phenomenon supplies new perspective for the designing of the molecules used as inhibitors, which is beneficial for the improvement of the adsorption durability of the potential used inhibitor after long period of immersion in acid medium.