Adsorption behavior of Polyphosphate-Zinc Inhibitor for Cooling Systems

• Published in: Hyōmen gijutsu Vol. 51; no. 9; pp. 945 - 950
• Main Authors: NAKAJIMA, Junichi, TSUCHIYA, Ryuji, TOGO, Naoko, ITO, Kenichi, ICHINO, Ryoichi, OKIDO, Masazumi
• Format: Journal Article
• Language: English
• Published: Tokyo The Surface Finishing Society of Japan 01.09.2000; Japan Science and Technology Agency
• Subjects: Adsorption; AFM Observation; Corrosion Inhibitor; Polyphosphate Zinc; QCM
• ISSN: 0915-1869; 1884-3409
• DOI: 10.4139/sfj.51.945

Adsorption behavior of a polyphosphate-zinc as corrosion inhibitor was examined on a gold electrode. While under a constant cathodic potential, the inhibitor's behavior was investigated in-situ by means of an electrochemical quartz crystal microbalance technique and surface observation using atomic force microscopy (AFM). The electrode potential (E), the concentration of dissolved oxygen (DO), the amount of polyphosphate-zinc inhibitor, and the solution pH affected on the cathodic current density and the change in the mass of the electrode. The amount of adsorbed inhibitor increased with an increase in the inhibitor concentration and concentration of dissolved oxygen, as well as with a decrease in the electrode potential at pHs7 and 8. The adsorbed amount reached 9μgcm-2 within 1200s at E=-0.75V with respect to a Ag/AgCl (sat. KCl) reference electrode in a 0.1moldm-3 Na2SO4 solution containing sodium hexametaphosphate (68ppm PO4), zinc chloride (20ppm Zn), and 20ppm poly-acrylic acid at pH7, DO=7.8ppm and 298K. The adsorpant was found to be several nanometers thickness according to AFM observation