Stability of Cu Species and Zeolite Structure on Ecological Heterogeneous Fenton Discoloration-Degradation of Yellow 5 Dye: Efficiency on Reusable Cu-Y Catalysts

摘要

The discoloration-degradation of yellow 5 dye was achieved through the heterogeneous Fenton reaction using Cu-Y catalysts. Cu-Y materials were prepared by an aqueous ion exchange method from the NH_4-Y parent zeolite. The solids are characterized by X-ray diffraction, nitrogen physi-sorption, EPR and, ~(27)Al and ~(29)Si NMR spectroscopies. Discoloration around 100% with 60% of COD removal was achieved before 90 min at 50℃ using the next reaction conditions: 50 mL of colored solution containing 50 ppm of dye, 0.129 mmol of H_2O_2, catalyst mass/volume of solution ratio (g L~(-1))= 0.016 and pH= 4-5. The influence of temperature and H_2O_2 concentration was also studied. The discoloration kinetics were modeled using the pseudo-first order reaction. High catalytic activity was observed even after four reaction cycles, which is credited to the good stability of the Cu species and the zeolite structure. Because the Fenton reaction was favored by the acid media provided by the Cu-Y catalyst and temperature, the addition of any acid was not necessary, avoiding the generation of sludge, resulting in an eco-friendly process.