ROLE OF HYDROGEN PROMOTERS ON CORROSION AND HYDROGENATION OF MILD-STEEL IN AQUEOUS AND METHANOLIC HYDROCHLORIC-ACID SOLUTIONS

Corrosion and hydrogenation of mild steel (MS) in aqueous and methanol ic solutions of hydrochloric acid (HCl) were studied using weight loss , electrochemical, and hydrogen estimation methods. The effects of som e hydrogen-promoting species such as cathodic poisons (i.e., sodium ar senite [NaAsO2], selenium dioxide [SeO2], stannous chloride [SnCl2], a nd mercuric chloride [HgCl2]) were investigated to understand their ro le on the dissolution and hydrogen absorption characteristics of MS in aqueous and methanolic HCl solutions. The dissolution rate of MS in m ethanolic solution of HCl was considerably higher than in the aqueous HCl solution, where as the hydrogen pickup values of the steel in meth anolic solution were less than in the aqueous HCL solution. Addition o f NaAsO2 lowered the dissolution rate and hydrogen pickup value in bot h solutions. The other poisons had specific effects on the dissolution rate and hydrogen pickup values.