Hexamethylenetetramine Hydroiodide (HMTA-I) as a Corrosion Inhibitor for Steel in HCI Pickling Solutions

ISSN： 0007-0599

Source： British Corrosion Journal, Vol.7, Iss.6, 1972-11, pp. : 276-280

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Abstract

The effect of hexamethy lenetetramine. hydroiodide (HMTA-I) as a corrosion inhibitor of steel in aqueous hydrochloric acid solutiOns has been investigated and its behaviourexamined as a function of HCI and inhibitor concentrations.A comparison with the inhibitive efficiency of hexamethylenetetramine (HMTA) shows that HMTA-I iS more efficient than HMTA, espcially at lower acid concentrations.Polarisation mesaurements show that the chemisorption of iodide anions and organic cations increases the overpotential for both hydrogen-ion discharge and metal ionisation.The adsorption oforganic cations, which in the case of HMTA is appreciable only at high HCI concentrations, iS enhanced in the case of HMTA-I by iodide adsorption at anodic areas.The surface coverage in 2M HCl has been calculated and the semi-empirical isotherm of Freundlich has been found to fit the results over the entire range of inhibitor concentration studied (up to 10^–2M ).