Rare Earth Doped ZnO Composite Material Experimental Study Of Photocatalytic Degradation Landfill Leachate Performance

Urbanization and industrialization of China produce a large of garbage.Landfill leachate is increasing in yield per day because of the construction of a largenumber of city garbage landfill. At present, rubbish classification is not mature inChina, leding to the city landfill leachate being problems of China’s industrialwastewater treatment with complex composition, water quality bio-refractory organic matter and toxic and harmful substances more and so on. So, It is very necessary tostudy the high efficiency and low energy consumption, energy saving andenvironmental protection water treatment new technology and new materials tosolve this kind of wastewater. ZnO nano material is well known as a kind ofsemiconductor material with excellent performance. It has been demonstrated thatthe properties of ZnO crystal is related to its surface morphology, size and innerstructure and reaction condition.In this study, The experimental study is divided into two parts. The first part isthe preparation of nano photocatalyst powder. Pure zinc oxide,europium-doped zincoxide(Eu-ZnO) nano-particles and gadolinium doped Zinc Oxide were prepared usinghydrothermal method by taking Zn(CH3COO)2, Eu(NO3)36H2O and Gd(NO3)36H2O as main ingredients, NaOH as precipitant, PEG2000as mineralizer（surfactant）, Citric acid as pH modulators（template）.Analytical methods, such asXRD, SEM,EDS and XPS were utilized in this study for characterization of thecrystalline phase,microstructure alloying element and specific area of the preparedpowder. The influence of reaction conditions on the microstructure of ZnO ceramicsis influence ofreaction temperature, reaction time, illumination conditions as well asthe doping ratio. The second part is the photocatalytic properties ofnano photocatalyst powder preparation.The main research achievements are as follows:(1) To determine the optimal doping amount of rare earth doped ZnO, theoptimum preparation conditions and the best reaction condition.Our results showed that pure zinc oxide,Europium-doped zinc oxide with a3%doping ratio andgadolinium doped Zinc Oxide with a0.1%doping ratio reached optimalphotocatalytic oxidation effect when the hydrothermal temperature was160℃andhydrothermal time was6hours. By utilizing the prepared powder under optimalconditions, after treatment of365nm UV irraditation for180min, the decolorizationrate of garbage leachate reached31.3%、40.0%and35.8%, the degradation rate ofCOD reached36.5%、62.0%and52.5%.（2）According to the data of leachate treatment plant daily operation of alandfill in Wuhan. The photocatalytic reaction was put forward for a method oflandfill leachate pretreatment process. The3%Eu doped ZnO composite photocat-alyst was prepared for leachate photocatalytic degradation experiments. Theresults showed that value of BOD5/CODcr of the leachate increased from0.32to0.43. The biodegradability of leachate has been greatly improved.