Suppression of corrosion in caustic manufacturing systems

摘要

The addition of a small amount of hydrogen or a hydrogen-liberating compound such as a metal hydride to a caustic solution serves to suppress the corrosive effect of the solution on nickel-based surfaces. Typical nickel-based surfaces include caustic evaporator surfaces which contain a caustic solution maintained at a temperature of from about 130 DEG C. to about 180 DEG C. A preferred metal hydride is sodium borohydride which is preferably present in an amount of from about 5 ppm to about 100 ppm. Concentrated caustic solutions containing less than 0.5 ppm of nickel can be prepared by this process.