CuCoAl-LDO/RGO Hybrid Visible-light Photocatalyst For Efficient Organic Dye Degradation

In recent years,the problem of water pollution caused by the discharge of all kinds of sewage has been paid more and more attention by people.As the country attaches great importance to the prevention and control of environmental pollution and proposes to resolutely win the battle of pollution prevention and control,people's sense of responsibility for strengthening the construction of ecological civilization and protecting the clear waters and green mountains is generally strengthened.Among them,printing and dyeing wastewater,as a kind of organic wastewater closely related to human beings,has the characteristics of strong toxicity,complex composition and great changes in water quality,so the difficulty of degradation is greatly improved.At present,a variety of technologies have been developed for the treatment of printing and dyeing wastewater.Among them,photocatalysis technology,as an emerging printing and dyeing wastewater treatment technology that uses solar energy to achieve the degradation of pollutants,has the advantages of high degradation efficiency,environmental friendliness,and no secondary pollution.And it is widely used.Layered Double Hydroxides(LDH)materials are widely used in medicine,catalysis,environmental management,etc.due to their good composition,tunability and stable chemical properties.It has a typical characteristic"memory effect",that is,it forms a cubic Layered Double Oxides(LDO)after calcination at a high temperature of 500°C.It has a better crystal structure and high specific surface area and can be used in a water-soluble environment.The characteristics of being regenerated into LDH make it the darling in the field of environmental pollution degradation.Since the graphene material was first exfoliated and prepared in 2004,its high mechanical strength,specific surface area,and excellent electrical and thermal conductivity have gradually become a common material in photocatalytic technology.Studies have shown that the composite of hydrotalcite and graphene materials can effectively enhance the conductivity and stability of the material,and this type of composite material has gradually become the mainstream trend in the study of photocatalytic composite materials for the degradation of pollutants.Studies have shown that the composite of hydrotalcite and graphene materials can effectively enhance the conductivity and stability of the material,and this type of composite material has gradually become the mainstream trend in the study of photocatalytic composite materials for the degradation of pollutants.In conclusion,CuCoAl-LDO/r GO composite material was prepared by using CuCoAl-LDH composite material as precursor and composite graphene oxide.By increasing its photocatalytic active sites,the photocatalytic performance of the material was significantly improved,and problems such as high electron-hole pair recombination rate and low visible light utilization rate of LDH photocatalytic material were solved.The main contents and results of this research are as follows:(1)CuCoAl-LDH and CuCoAl-LDH/GO precursors were successfully prepared using single drop co-precipitation,and CuCoAl-LDO/RGO composites were calcined under nitrogen protection,and XRD,XPS,SEM,TEM,etc.were performed Characterization,the results confirmed that the CuCoAl-LDO/RGO composite material was successfully prepared and the LDO and RGO composite was in good condition.The introduction of RGO significantly reduced the recombination rate of charge carriers,improved the visible light utilization rate,and effectively improved the photocatalytic performance.(2)In the photodegradation experiment,an ultraviolet spectrophotometer and a TOC/TN analyzer were used to analyze the concentration and degree of mineralization of the pollutants.The results proved that compared with the individual LDH,LDO and LDH/GO materials,CuCoAl-The photocatalytic performance of the LDO/RGO composite material is significantly improved.The degradation rate of 25ppm Methylene blue was 99.9%in 3h,and 96.4%in 2h for 221.9 ppm of Congo red and the catalytic effect has the best value when the Co/Cu ratio is 3:1.The photocatalytic degradation effect conforms to the first-order kinetic model,that is,the reaction rate is proportional to the concentration of pollutants.(3)Free radical capture experiments confirmed that the photocatalytic active species h⁺,·OH and·O₂^-are all involved in the catalytic reaction,and the order of influence on the reaction is·O₂^->h⁺>·OH.In addition,CuCoAl-LDO/RGO composites showed good stability and excellent recyclability in the repeated experiments with 5 cycles.