The Preparation Of Ce And Nd Doping Activated Carbon-supported Catalysts And Application In Wastewater Treatment

With the rapid development of modern industrial,a large number of untreated or substandard industrial wastewater discharging indiscriminately,has caused serious pollution to the environment and threatened human health.The advanced treatment technology researches of industrial wastewater have become an important research direction.This paper refers to Chinese patent:CN2012103983710.Some amounts of metallic oxide supported on activated carbon（denoted as AC）are assembled in a tailor-made rectangular wire mesh bag,and the‘new’whole wire mesh bag is used as composite anode in the degradation of organic substance.This method can integrate the processes of anodic oxidation with electrogenerated H₂O₂,MO_x/H₂O₂Fenton-like and AC physical absorption,and it may improve the efficiency of the original electro-generated H₂O₂-AO process.At the same time,the catalysts of metallic oxide supported on activated carbon are much cheaper than noble metals.In this dissertation,first of all,rare earth element Ce,Nd catalysts supported on AC are prepared by sol gel method.It can achieve the rapid degradation of phenol and methyl orange pollutants by optimizing the experimental conditions.In addition,the characterization tests of rare earth element Ce,Nd catalysts supported on activated carbon（denoted as Cu/Ce-AC and Cu/Nd-AC）,reveal the inner mechanism of catalytic oxidation.The main results are as follows:1.The research progress and reaction mechanism of advanced oxidation process（AOPs）and electrochemical advanced oxidation process（EAOPs）in industrial water treatment have been briefly reviewed,and the research purpose,significance and innovation of this master’s thesis are also clarified.2.Cu-AC,Cu/Cu-AC and Cu/Nd-AC catalysts are prepared by sol gel method,after that a certain amount of homemade catalysts are added to the 304 stainless steel mesh bags which possess the same geometry and area,and then the‘new’whole 304stainless steel mesh bags are used as the composite anodes.It is found that the activities of Cu-AC,Cu/Nd-AC,Cu/Ce-AC composite anode in terms of oxidation degradation of phenol has an increasing trend according to the marshalling sequence,COD removal rate of phenol wastewater in 50 min can reach 80.34%,93.16%and97.88%,respectively.According to BET detection,It is found that the specific surface areas of Cu/Nd-AC（788.006 m²/g）and Cu/Ce-AC（816.957 m²/g）are bigger than the modified AC（695.453 m²/g）,and modified AC’s is greater than the Cu-AC’s（632.214 m²/g）.According to SEM tests,it is found that modified AC surface is rather smooth,and the hole is clearly visible on the surface.Lots of small uniform particles are deposited on surface of Cu/Ce-AC and Cu/Nd-AC,however,the particles on the surface of Cu-AC are mostly fragmented,this may be the main reason that Cu-AC specific surface area is less than modified AC.By XRD testing,it is found that the surface compositions of Cu-AC,Cu/Nd-AC and Cu/Ce-AC are almost the same,and CuO is the mainly component.It is failed to detect the oxide of Nd₂O₃and CeO₂on the surfaces of Cu/Nd-AC and Cu/Ce-AC,due to the low elements content of Nd and Ce.The cell volumes Cu/Nd-AC and Cu/Ce-AC has an increasing tendency in relative to Cu-AC,and the maximum unit cell volume of Cu/Nd-AC is 88.9983?³,this may be due to ion radiusCu²⁺（73 pm）<Ce⁴⁺（97pm）<Nd³⁺（98pm）.But the average grain size on the surface of Cu-AC,Cu/Nd-AC and Cu/Ce-AC has a decreasing tend,Cu/Nd-AC has a minimum average grain size and it is 121.374nm.Through XPS characterization,it can reveal the primary reason of Cu/Nd-AC,Cu/Ce-AC composite anode having higher oxidation activity than that of Cu-AC composite anode.Although surface adsorption oxygen content of Cu/Nd-AC is slightly lower than that of Cu-AC,but Cu/Nd-AC composite anode has stronger ability in oxidation degradation of phenol than Cu-AC composite anode.This may be due to the surface adsorption water contents of Cu/Nd-AC and Cu/Ce-AC are higher than that of Cu-AC,and surface adsorption water content directly involves·OH generation in the Raff system,directly affects the oxidation ability of Cu/Nd-AC and Cu/Ce-AC composite anode.3.Firstly La_1-xNd_xFe O₃-AC（x=0,0.2,0.4,0.6,0.8,1.0）supported catalysts are prepared by sol gel method,and then La_1-xNd_xFeO₃-ACcomposite anodes are made as above for the degradation of methyl orange.According to XRD measurement,the cell volumes and average grain sizes of La_1-xNd_xFeO₃-AC have a decreasing trend when the percentage of Nd in La_1-xNd_xFeO₃-AC are increased.According to SEM measurement,when x is equal to 0,the grains on the surface of LaFe O₃-AC are mainly in pieces（blocks）and powder form.When x are equal to 0.2,0.4,0.6,0.8,the proportion of block grains on the surface of La_1-xNd_xFeO₃-AC are reduced,but the proportion of powder grains are increased gradually.When x is equal to 1.0,it begins to appear block grains on the surface of NdFeO₃-AC.Due to the higher pH_PZC of La_1-xNd_xFeO₃-AC as x value increased,the methyl orange（MO）adsorption of La_1-xNd_xFeO₃-AC has an increasing trend.In terms of oxidative degradation of methyl orange,La_0.6Nd_0.4FeO₃-AC composite anode has the strongest oxidation ability,MO methyl orange wastewater and COD removal rate during 10 min can reach 99.81%and 99.81%,respectively.According to ultraviolet spectrum detection,the absorption peak of methyl orange wastewater in 507 nm has been disappear entirely,and it confirms that MO has been thoroughly degraded.