Theoretical Study On The Synergistic Effect Of Oleic Imidazoline And Mercaptoethanol Corrosion Inhibitor

Nowadays,corrosion,which causes huge losses,is a common problem.Adding corrosion inhibitors,among so many ways to prevent corrosion,is one of the most effective methods.Imidazoline derivatives and mercaptoethanols have been proved to be effective corrosion inhibitors.However,there are a few investigations on the synergistic effect between them.In order to provide theoretical basis for developing new corrosion inhibitors,the mechanism of the synergistic effect between oleic imidazoline(OIM)and mercaptoethanol(ME)was investigated theoretically.On the one hand,the concentration effect of OIM was considered.The adsorption model with different OIM concentration was built.On the other hand,the ratio of OIM to ME was considered.The adsorption model with different ratios of OIM to ME was built,and the ratio of OIM-ME were 1:5,1:3,1:1,3:1,5:1.Ultimately,the configuration,adsorption energy and the ability to repulse water of corrosion inhibitor film were studied through molecular dynamics simulation to analyze not only the relationship between the OIM concentration and the efficiency but also the mechanism of the synergistic effect between OIM and ME.The main conclusions are as follows.1.OIM molecules are able to adsorb on the surface of iron to form a film to protect iron in water.The inhibition efficiency of OIM increases with the increasing of OIM concentration when the concentration of OIM is lower than the critical value,and it decreases with the increasing of OIM concentration when the concentration exceeds the critical value.2.The adsorption energy of OIM is bigger than that of ME.And OIM is the main substance that constitutes the inhibitor film,while ME molecules fill the cavity of the film and occupy active center to make it denser.When the ratio of OIM to ME equals 3:1,the OIM-ME inhibitor shows the best inhibition efficiency.Besides,the best temperature is 308 K for the adsorption of OIM-ME inhibitor.3.The mechanism of the synergistic effect between OIM and ME in the solution of NaCl is still the same with which in water.Besides,as the proportion of OIM in OIM-ME inhibitor increases,the inhibition efficiency of it increases at first and then decreases.The OIM-ME inhibitor shows the best inhibition efficiency when the ratio of OIM to ME equals 3:1.