THE ROLE OF DIHYDROXYBENZENES AND OXYGEN ON THE CORROSION OF STEEL INBLACK LIQUOR

The effects of substituted phenols on the electrochemical and corrosio n behavior of A-283 Gr C steel in alkaline solutions at 65 degrees C h ave been determined. Dihydroxybenzenes with adjacent hydroxyl groups i ncreased the critical current density for passivation substantially. H omogeneous oxidation of dihydroxybenzenes by dissolved oxygen can lead to dramatic increases in the corrosion potential of the steel due to the formation of quinones. In the presence of sulfide ions, this alter ed solution can lead to pitting at elevated potentials. Higher concent rations of 1,2-dihydroxybenzenes prevent passivation upon aeration, le ading to high rate, uniform corrosion. The implications of these resul ts on the corrosion of steel storage tanks in the pulp and paper indus try are discussed. Copyright (C) 1996 Elsevier Science Ltd.