Chemical removal of thiourea from hydrochloric acid

摘要

A chemical method of removing thiourea from spent hydrochloric acid cleaning solutions comprising the steps of: adjusting the pH to not less than 12 by addition of base to remove metal hydroxides; oxidizing thiourea to urea by the addition of at least 4 moles of hydrogen peroxide per mole of thiourea; and further oxidizing urea to nonregulated/nonhazardous compounds by the addition of at least 3 moles of a hypochlorite per mole of urea. UV analysis confirms a greater than 98% removal of thiourea from solutions containing 0.4 to 2.7 wt. % thiourea after as little as 3 hours with an exotherm, DELTA t, of less than 105 DEG F.