Experimental And Theoretical Study Of Azole Corrosion Inhibitors’ Performance Evaluation And Adsorption Mechanism On Cu Surface

Copper and copper alloy are widely used in many fields.But they can corrodes seriously in some severe environment such as SO2、H2S and Cl2 gas medium and ammonia、aminium salt and chlorine solution.Adding corrosion inhibitor is one of the most efficient anti-corrosion method because of its many advantadges.In this paper,Imidazole(IMD)、triazole(TRI)、Benzimidazole(BIMD)and benzotriazole(BTA)are selected as research objects to study their inhibition performance and inhibition mechanism in two ways,experiment and Molecular Simulation.At first,we evaluate the inhibition efficiency of the four corrosion inhibitors with experimental method,and their inhibitor type and Adsorption isotherm model are analyzed too.Secondly,building the relationship between the inhibition efficiency and global active parameters of the four corrosion inhibitors through analysing their global active parameters.Thirdly,confirm the active sites of the four corrosion inhibitors by means of analysing their local activity parameters.At last,we build the adsorption model between the corrosion inhibitors and Cu surface to study their electron structure parameters.And we get the adsorption mechanism of the corrosion inhibitors and Cu surface eventually.Through all the studies,we can drew the conclusions below:The inhibition efficiency order of the four inhibitors from highest to lowest is: BTA>BIMD>TRI>IMD,and all of the four inhibitors are mixing type inhibitors.Their adsorption on Cu surface conform the Langmuir adsorption isotherm,with both chemisorption and physical adsorption.Frontline orbital(HOMO and LUMO)of the four corrosion inhibitor molecules have the same distribution center,all distributing at the rings of the molecules,and the nucleophilic activity centers and the electrophilic activity centers of the four molecules mainly concentrate in the heteroatoms N atoms.The global active parameters of the four corrosion inhibitors such as chemical potential(μ)、hardness(η)、softness(S)、enegy gap(ΔE)and electrophilic index(ω)have good correlation with the the inhibition efficiency.So we can use above parameters to Forecast inhibition efficiency.All of the four corrosion inhibitor molecules can chemically and physically adsorb on Cu surface,and the adsorption energy of the molecules is in accord with the inhibition efficiency obtained by experiment;The corrosion inhibitor chemisorb on Cu surface via the formation of chemical bond between N atom and Cu atom,and this type of chemical bond is covalent bond.And the interaction between N atom and Cu atom is due to the atomic orbits hybridization.The physical adsorption between the inhibior and Cu surface include both Van der Waals forces and electrostatic attraction.