Study On Mechanism Of Copper Corrosionand Inhibition Effect Of Domperidone On Copper In Hydrochloric Acid

Copper is an important metal material, it has excellent mechanical properties, good thermal and electrical conductivity and it is relatively stable in nature, so it is widely used in industrial production. But in extreme environments, especially in the presence of a large number of chloride ions and acid, copper could occur serious corrosion phenomenon which might bring life and production huge losses and even disaster. Thus, copper corrosion is particularly important. There are a lot of measures for copper corrosion now, of which the use of anti-corrosion inhibitors is a safer and more efficient method, especially organic corrosion inhibitors. In recent years, research efforts have been concentrated on the exploration of new green corrosion inhibitors.In order to prevent the corrosion of copper, the corrosion mechanisms of coppershould be studied first. In this paper, the electrochemical behavior of copperwas investigated, firstly, in different concentrations of hydrochloric acid, sodium chloride and sulfuric acid solution by Electrochemical impedance spectroscopy（EIS） and potentiodynamic polarization. There was a distinctgap in corrosionpotential between hydrochloric acid and sulfuric acid solution. Itindicates that copper is more vulnerable to corrosion from the view of thermodynamics. The result of EIS shows that copper corrode faster in acid. The negative resistance tested in 0.001 M hydrochloric acidproves that Cu₂ O film formed on copper surface.In this paper, the corrosion inhibition efficiency of domperidone was studied in different concentrations of hydrochloric acid by weight loss, electrochemistry tests, field emission scanning electron microscope（FESEM）, Energy Dispersive X-Ray Spectroscopy（EDX） and Langmuir adsorption.And the inhibition mechanism was also discussed.The results of open circuit potential（OCP） indicates that copper surface was passivated in 0.01 M and 0.001 M hydrochloric acid. OCP shifted to negative after adding domperidone. And the largest shift is 113 mV, which confirms that domperidone acts as acathodic inhibitor for copper in hydrochloric acid solution. The inhibitive efficiency 92.2% was measured byweight loss in 0.01 M hydrochloric acid. It was thehighest value. The results of potentiodynamic polarization shows that domperidonehas has excellent protective ability for copper corrosion. Also the inhibitive efficiency of domperidone reached the highest value 98.5 in 0.01 M hydrochloric acid solution by EIS as by weight loss. Surface morphologyobservation was performed to further confirm the inhibition action of domperidone using FESEM. The element content analysis of EDX reveals that copper surface generated a small quantity of CuCl in 1 M hydrochloric acid and Cu₂ O in 0.001 M hydrochloric acid. Finally, it was found that the adsorption of domperidone on copper surface in hydrochloric acid solution obeys the Langmuir adsorption and ?G_ads=- 42.23 kJ/mol. It reveals that domperidone adsorbs on copper surface by chemical adsorption in hydrochloric acid solution.