The Behavior of Zinc Metal in Alkaline Solution Containing Organic Inhibitors: I. Electrochemical Studies of Zinc

Abstract

The electrochemical behavior of zinc in strong alkaline solutions containing 8.5 M of potassium hydroxide (KOH) and polymeric organic inhibitors was evaluated. The concentrations of the organic inhibitors studies were in the range of 400-4000 ppm and included polyethylene glycol (PEG), with a molecular weight of 300-900, and polyoxyethylene alkyl phosphate ester acid form (GAFAC RA600). The electrochemical studies included potentiodynamic and potentiostatic polarizations. The inhibition properties of PEG 600, in the strong alkaline solution, are by far much more efficient than the inhibition capability of the other polymers. The studies also indicate that evaluation of the inhibitors should be conducted as a function of storage time. The evaluation of other polymeric compounds established that the polymer must contain a linear polyoxyethylene backbone with a chain length of ∼10 units with an optimal polymer concentration in the range of 800-2000 ppm. The described electrochemical methods are suggested as a rapid tool in the evaluation of organic polymers inhibitors, offering a precise determination of the optimal concentration in the alkaline media. © 2003 The Electrochemical Society. All rights reserved.