Photocatalytic And No Light Degradation Behavior Of Methyl Orange On Cu₂O/Zeolite Composite Materials

Photocatalytic oxidation technology is an emerging environmental protectiontechnology of the high ability to deal with the water pollution. Cuprous oxidesemiconductor is one of the most effective, commonly used photocatalyst in theheterogeneous photocatalytic technology. Due to the shortcomings of difficult torecycle and low utilization rate of light, this paper proposes a chemical modificationmethod to cuprous oxide, make the cuprous oxide powder photocatalyst not only hasgood photocatalytic activity, but also can be used repeatedly in the photocatalyticreaction. The innovation of the paper is to found the degradation behavior of cuprousoxide/zeolite composite for methyl orange under the condition of dark and has taken apreliminary discussion.In this paper, Cu2O/zeolite composite materials is synthesized successfully bychemical reduction deposition in HAc/NaAc buffer system using CuSO4·5H2O as thereactant, Na2SO3as the reductant, and zeolite as the carrier. The composition,morphology and structure of the composites are characterized by XRD, SEM andEDTA complexometric titration. By XRD spectrum, cuprous oxide crystal is found inzeolite, and Cu2O/zeolite composite photocatalytic materials was formed. By SEMgraph, Cu2O crystal growth on zeolite with whisker, Cu2O whisker is about1-2μm,and Cu2O/zeolite composite photocatalyst particle size of about13-15μm, whichfavours for recycle.The Cu2O/zeolite composite materials prepared in laboratory is chosen as thephotocatalyst, and methyl orange, an anionic dyes, as the model pollutant in thephotocatalytic degradation experiments. Under the condition of visible light, itsphotocatalytic degradation performance and reusability was studied. Experimentalresearch shows that zeolite has no photocatalytic degradation characteristics to methylorange; and the effect of Cu2O/zeolite composite photocatalyst is better than the purecuprous oxide. The Cu2O/zeolite composite photocatalyst still has good degradationcharacter after repeated for several times under the best degradation condition. On theother hand, the factors which affect photocatalytic degradation of dyes areinvestigated by the variation of absorbance, such as the addition amounts of catalyst,initial concentration of methyl orange and the changes of reaction temperature. The result shows that along with the increase of the amount of catalyst, the photocatalyticdegradation rate increases at first and then decreases, when the concentration of Cu2Oin reaction system is0.5g/L, the degradation effect of methyl orange is the best, thedegradation rate could be of83.74%after55min. The initial concentration of methylorange is significantly influenced to catalytic degradation rate. Increasing the initialconcentration of MO, the trend of degradation rate is increasing at first and thendecreasing, when the initial concentration of methyl orange is25mg/L, thedegradation rate of maximum. And last, temperature is a very complex factor tophotocatalytic reaction, degradation rate of methyl orange rose with the increase ofthe reaction temperature at the first15min, and changes very fast, the relatively hightemperature reaction will be faster to balance. After15min, the degradation rate ofmethyl orange rise at first and then decrease with the rise of temperature, thedegradation rate of maximum at40℃, it’s about88%after60min.In the study of photocatalytic degradation of methyl orange using theCu2O/zeolite composite material as catalyst under the condition of visible light, thedegradation features of the composite materials for methyl orange under the conditionof dark was discovered. Aiming at the phenomenon, this paper preliminary discussedthe degradation behaviour of methyl orange using the Cu2O/zeolite compositematerials prepared in laboratory under the condition of no light. By studying thephenomenon of Cu2O/zeolite composite photocatalyst degradation of methyl orangeunder different temperature, the results show that temperature is a very sensitivefactor on the degradation rate for methyl orange under the condition of dark. Itconfirmed from another side that the degradation of no light is different from visiblelight catalytic degradation. In addition, increasing the condition of light, the changesin the process of the degradation for methyl orange is complex, this is because afterincreasing light, the photocatalytic oxidation reaction is triggered.