Catalytic Ozonation Of Acid Red B And Acid Scarlet GR By Metal Oxide

Dyes induce a significant threat to human health and ecological systems due to their widespread use, carcinogenic characteristic of degradation byproducts and low biodegradability. This study used azo dyes Acid Red B and Acid scarlet GR as the research objects, investigated the influence of preparation and reaction conditions on catalytic ozonation of Acid Red B and Acid scarlet GR, and explored the catalyzing mechanism. The main results are as follows:A series of metal oxide catalysts were prepared by nitrate-citrate combustion route, the iron and Fe-Cu oxide had better catalytic effect on ozone oxidation. When adding iron and Fe-Cu oxide for 20 min, the removal rate of acid red B increased by 7% and 24%, which compared with ozone alone. After 60 min reation, the COD removal rate of adding iron and Fe-Cu oxide were 60% and 70%, while ozone alone was 48%. The results of EDS and catalyst repeated experiment showed that the catalyst had good stability. It is suggested that the catalyzing mechanism of catalytic ozonation of Acid Red B by Fe-Cu mixed oxide were: dissolved ozone were decomposed to hydroxyl radicals by the catalyst surface hydroxyl groups, and then hydroxyl radicals and dissolved ozone oxidated Acid Red B which in solution or chemical adsorption on the catalyst surface. The main degradation intermediate product of Acid Red B was acetic acid. The degradation pathway of acid red B was deduced, and the kinetics model of acid red B and COD degradation were established. In three systems, the degradation of acid red B and COD met pseudo first-order kinetics equation. A series of alumina catalysts were prepared by impregnating method, the Co/Al₂O₃ and Ni-Co/Al₂O₃ had better catalytic effect. The best preparation conditions of catalysts were: 2% of Co loading, Stirring for 4h, calcination for 2h, calcination temperature was 500℃, 2% of Ni loading. After 10 min reation, the Acid Scarlet GR removal rate of adding Co/Al₂O₃ and Ni-Co/Al₂O₃ were 69% and 80%, while ozone alone was 54%. After 45 min reation, the COD removal rate of adding Co/Al₂O₃ and Ni-Co/Al₂O₃ were 59.4% and 78.6%, while ozone alone was 28.6%. The results of EDS, surface area, SEM and catalyst repeated experiment showed that the catalyst had good stability. It is deduced that the catalyzing mechanism of catalytic ozonation of Acid Scarlet GR with Ni-Co/Al₂O₃ were: dissolved ozone were decomposed to hydroxyl radicals by the catalyst surface hydroxyl groups, and then hydroxyl radicals and dissolved ozone oxidated Acid Scarlet GR which in solution and physical adsorption on the catalyst surface. The degradation pathway of Acid Scarlet GR was deduced, and the kinetics model of Acid Scarlet GR and COD degradation were established. In three systems, the degradation of Acid Scarlet GR and COD met pseudo first-order kinetics equation.