OXIDATIVE DESTRUCTION OF THIOUREA IN BOILER CHEMICAL CLEANING WASTE SOLUTIONS

Thiourea and its lower homologues are uniquely useful in an acidic pro cess for dissolving utility power plant boiler scales containing iron oxides and copper. The oxidative destruction of thiourea in boiler che mical cleaning waste (BCCW) solutions can be easily accomplished by ne utralizing the acid to an excess of the base, adding powdered charcoal and sparging with air or O2. The major reaction path leads to dicyand iamide and sodium thiosulfate A minor reaction path produces urea and sulfur. Using 0.5-2% powdered charcoal and an aeration rate of 7.5 mL/ min-1 100 mL-1, thiourea is reduced from 2% (0.263 mol/L) to detection limits within 24 h or less.