The use of waste basic oxygen furnace slag and hydrogen peroxide to degrade 4-chlorophenol

A new treatment method is developed to degrade 4-chlorophenol (4-cp) and its oxidation intermediates. The experimental results of this research demonstrate that 4-cp and its oxidation intermediates can be decomposed completely by basic oxygen furnace slag (BOF slag) with hydrogen peroxide (H2O2) in an acid solution. The factors that effect the treatment efficiency were studied including initial concentration of 4-cp, pH of the solution, concentration of H2O2 and amount of BOF slag. The BOF slags are final waste materials in the steel making process. The major components of BOF slag are CaO, SiO2, Fe2O3, FeO, MgO and MnO. As the BOF slag in an acid solution, FeO and Fe2O3 can be dissociated to produce ferrous ion and ferric ion. Ferrous ion reacts with hydrogen peroxide to form "Fenton's reagent" which can produce hydroxyl radicals (OH.). Hydroxyl radical possession of high oxidation ability can oxidize organic chemicals effectively. Results show that 100 mg/l of 4-cp is decomposed completely within 30 min by 438.7 g/l BOF slag with 8.2 mM hydrogen peroxide in pH = 2.8 +/- 0.2 solution. The COD value of the solution is reduced from 290 to 90 mg/l. The factors studied which affect the 4-cp decomposition efficiency were the hydrogen peroxide concentration, BOF slag concentration, pH of the solution and initial concentration of 4-cp. Because large amounts of Fe2O3 and FeO are present in the BOF slag, the BOF slag not only has a high treatment efficiency, but also can be used repeatedly. (C) 1999 Elsevier Science Ltd. All rights reserved.