Improvement of Solubility of Corrosion Inhibitor by Sulfite and its Influence on Iron Passivation in Absorption Refrigeration Systems

Abstract

In absorption refrigeration systems, molybdate is used as a key inhibitor against corrosion of steel, although it is liable to precipitate because of its limited solubility in a concentrated LiBr solution. In this research, the use of sulfite is proposed as a precipitation inhibitor for molybdate and its effect on the passivation of iron is examined. The effect of the stronger passivator of nitrate on the actions of sulfite is also investigated. The results show that sulfite decreases the amount of corrosion of iron and promotes the formation of the oxide layer （MoO₂, Fe₃O₄） on the surface of iron irrespective of presence of nitrate. Thus, sulfite is concluded as an effective additive in an absorption refrigerator for better control of molybdate concentration and corrosion of iron.