Simulation Of Corrosion Inhibition Behavior Of Nitrogen-containing Heterocyclic Organic Molecules On Copper Surface

Organic corrosion inhibitors have become the focus of corrosion inhibitor research due to their excellent corrosion inhibition efficiency and high economic benefits.In order to further improve the corrosion inhibition efficiency and reduce costs,two or more corrosion inhibitors are mixed and used.Currently,nitrogen-containing heterocyclic organic molecules such as BTA are often used as bronze corrosion inhibitors,but their mechanisms need to be further studied.Therefore,this article selects BTA and AMT as the research objects to study the single and synergistic mechanism of nitrogen containing heterocyclic organic molecules from a theoretical perspective,providing theoretical support for the practical application of bronze corrosion inhibitors.The reaction activity of BTA molecule and its adsorption behavior on Cu（100）,（110）and（111）surfaces were studied by density functional theory.The results showed that the adsorption energy of BTA molecule on three different orientation copper surfaces was:Cu（110）_x>Cu（100）_x>Cu（111）_x（x=T,B,H）;The outermost valence electron of Cu atom and N（2）atom of BTA corrosion inhibitor molecule form coordination bond;The bonding between N atom and Cu atom of BTA molecule is the hybridization of N＿2s,N＿2p and Cu＿3d.Adsorption sites and the ability of atoms to gain and lose electrons have been studied from the frontier orbitals of AMT isomers and Fukui indices of each atom.The results indicate that the frontier orbitals of AMT are delocalized from the thiadiazole ring and polar functional groups such as amino,imino,and thiol groups,tending to form parallel adsorption configurations on the substrate.Among the four AMT isomers,AMT-c exhibits the best corrosion inhibition performance,with local reaction sites mainly located at S（7）atoms.The corrosion inhibitor film density and water molecule displacement ability of AMT combined with urea increase with the increase of AMT concentration at 298 K.When the composite ratio is 3:1,the adsorption energy is564.81 kcal·mol^-1.The adsorption of AMT on copper surface belongs to chemical adsorption,where N and S atoms in AMT form coordination bonds with Cu atoms.