On the inhibitive action of some N-Decyl-Pyridinium bromide derivatives on the iron dissolution in 1N hydrochloric acid solutions.

The inhibiting action of N-Decyl-Pyridinium Bromide and some of its derivatives on the iron dissolution in 1 N HCl at 25; 50; 70 °C temperatures has been studied. The tested substances inhibit both the anodic and the cathodic reactions. The introduction in the pyridine ring of -OH or -COOH substituents, as well as -CH3 group in the position 3 (or positions 3 and 5) enhanced the inhibiting performances of the quaternary ion. At low temperature N-Decyl-3-hydroxy-Pyridinium Bromide is the most efficient compound, while at high temperature N-Decyl-3-carboxy-Pyridinium Bromide is the most efficient one. Similar effects are also found in sulphuric acid solution when the substances are examined both as bromide or as sulphate salts. A purely physical-type adsorption cannot completely explain the effects found