SYNERGISTIC EFFECTS OF INORGANIC AND ORGANIC CATIONS ON INHIBITIVE PERFORMANCE OF PROPARGYL ALCOHOL ON STEEL DISSOLUTION IN BOILING HYDROCHLORIC-ACID SOLUTION

The role of different inorganic cations of several elements and organi c materials in combination with different concentrations of propargyl alcohol (PA) was investigated in an effort to control the dissolution of mild steel in boiling (102 +/- 1-degrees-C) hydrochloric acid (HCl) solution. Inorganic cations of chromium (Cr6+), arsenic (As3+), tin ( Sn2+), copper (Cu2+), nickel (Ni2+), and mercury (Hg2+) were studied. Organic materials studied included phenol, formaldehyde, O-aminobenzoi c add, sodium hypophosphide, and hydroquinone. Cr6+, As3+, and Ni2+ pr ovided higher synergism, followed by Cu2+, Sn2+, and Hg2+. Phenol and formaldehyde provided higher beneficial effect. Except for phenol and formaldehyde, the other organics stimulated corrosion when added at hi gher concentrations. Organic additives were more effective than inorga nic cations. Cu2+, Cr6+, and Ni2+ accelerated corrosion when used with out PA but strongly reduced dissolution in its presence. As3+ reduced the corrosion rate alone and in combination with PA. Open-circuit pote ntial measurements and polarization studies indicated PA controlled th e corrosion rate by formation of a surface layer at the interface. Its effect was enhanced if another specie was present in the solution tha t promoted the film formation.