Catalytic Degradation Of Methyl Orange Over Cu-bearing Catalysts Under Microwave

Dyes in textile or dye industry are becoming a serious environmental problem due to their inherent characteristics such as toxicity,high chemical oxygen demand and non-degradability.Among various dyes,methyl orange?MO?is difficult to degrade and is often used as a model dye pollutant.In recent years,microwave has been widely used in water treatment technology and achieved good treatment effect.Therefore,this study established the MW auxiliary system of copper base catalyst oxidation degradation of methyl orange,the preparation of the copper silicon carbide?Cu/SiC?and load activated carbon copper?Cu/GAC?two kinds of catalysts,reaction time,catalyst dosage,H₂O₂dosage,microwave power and parameters such as initial pH on the effects of methyl orange degradation rate,and study the microwave assisted copper base catalyst oxidation mechanism of H₂O₂ degradation of methyl orange,the results are as follows:?1?With silicon carbide and activated carbon respectively two different absorbing material as the carrier,active component for copper ion,the dip-roasting the load type catalyst Cu/SiC and Cu/GAC,impregnation liquid is 0.6 mol/L nitric acid copper solution,calcination temperature 300?,roasting time 3 h.?2?The characterization of SiC and Cu/SiC before and after copper loading,and of GAC and Cu/GAC before and after copper loading were analyzed by field emission scanning electron microscopy?SEM?,electronic energy spectrum analysis?EDS?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and other detection methods.The active component copper presented irregular shape on the surface of the carrier,mainly in the form of CuO,and the copper load in Cu/SiC and Cu/GAC were 6.61%and 6.65%,respectively.?3?The prepared Cu/SiC was used as the catalyst and H₂O₂ as the oxidant.In the MW-Cu/SiC-H₂O₂ system,0.2 g catalyst,0.3 ml oxidant,600 W microwave power,pH=7were used.The degradation rate of methyl orange reached 97.5%within 8 min.Kinetic analysis showed that the degradation of methyl orange in MW-Cu/SiC-H₂O₂ system was in line with the first order kinetic equation.Comparing the removal of methyl orange in different systems,the results show that the degradation rate of methyl orange is the best in the microwave-assisted Cu/SiC catalyzed H₂O₂ oxidation system,and the microwave-assisted not only involves heating,but also has synergistic effect with catalysts and oxidants.Through free radical scavenging experiment,hydroxyl radical was proved to be the reason of methyl orange degradation.The catalyst Cu/SiC still has high catalytic activity after 5 times of use,and the removal rate of methyl orange can still reach over 90%.The prepared Cu/SiC has good stability and can be reused for many times.?4?The prepared Cu/GAC was used as the catalyst and H₂O₂ as the oxidant.In the MW-Cu/GAC-H₂O₂ system,0.2 g catalyst,0.3 ml oxidant,600 W microwave power,pH=7were used.The degradation rate of methyl orange reached 93.7%within 8 min.Comparing the removal of methyl orange in different systems,the results showed that the degradation rate of methyl orange was the best in the microwave-assisted Cu/GAC catalyzed H₂O₂oxidation system,and the microwave-assisted system was not only heating,but also synergistic effect between the catalyst and oxidant.Through free radical scavenging experiment,hydroxyl radical was proved to be the reason of methyl orange degradation.The catalyst Cu/GAC still has catalytic activity after 5 times of use,and the removal rate of methyl orange can reach over 80%.The prepared Cu/GAC is basically stable,and appropriate regeneration method is needed to maintain the activity of the catalyst.