Effect of mineral compounds in phosphoric acid polluted by sulphide ions on corrosion of nickel

Abstract

The inhibiting effects of two mineral compounds on corrosion of nickel in phosphoric acid (H3PO4) polluted by sulfide ions (S2−) was studied using electrochemical and spectroscopic techniques. Electrochemical measurements showed addition of bentonite or phosphate mineral reduced the corrosiveness of H3PO4 polluted with S2− considerably. X-ray photoemission spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) showed these inhibitors did not incorporate into the passive film of the material and, therefore, did not induce any change in capacitance of the passive film. Results suggested the inhibiting effect stemmed from avoiding the adsorption of S2− ions on the nickel surface.