Uptake of Hydrogen By Certain Organic Inhibitors During Pickling of Steel In Hydrochloric Acid

An apparatus was designed for and experiments conducted to determine precisely and simultaneously the volume of hydrogen evolution and steel corroded by inhibited and uninhibited hydrochloric acid. A theoretical concept of the probable reactions is described. Hydrogen uptake and iron dissolved are tabulated for a number of experiments with and without inhibitors and with and without a hydrogen absorber. Influence of variables inherent in the experimental method is discussed with respect to accuracy of results. Evidence was found that the inhibitor DHQ displaces hexamine at the surface and thus prevents “uptake” of hydrogen by the hexamine. DHQ and hexamine were much more effective together in reducing the rate of hydrogen evolution than was DHQ alone. 4.3.2, 5.9.2, 5.8.3