Preparation And Application Of Flower-shaped Cerium Oxide

In this thesis,cerium oxide with flower-like morphology was prepared by liquid-phase precipitation using Ce（NO₃）₃ as raw material,polyvinylpyrrolidone（PVP）as template agent and ammonium bicarbonate（NH₄HCO₃）as precipitant.The morphology,physical phase and crystal structure of the prepared cerium oxide were also physically characterized by SEM,XRD,Fourier infrared spectroscopy,laser particle size meter,physical adsorption meter,UV-Vis absorption spectroscopy and average kinetic friction coefficient.The molecular weight,R-value,p H of the initial feed solution and Ce³⁺concentration of the initial raw material of the template agent PVP were mainly discussed on the morphology of the prepared flower-like cerium oxide,and the formation mechanism and application of the prepared flower-like cerium oxide were also discussed.The optimum experimental conditions for the preparation of flower-shaped cerium oxide are:the molecular weight of PVP is K23～27,the R value is 3:1～4:1,the p H value of the initial feed solution is 5,and the Ce³⁺concentration of the initial feed material is 0.01M.The particle size of the prepared flower-shaped cerium oxide is more uniform and normally distributed,and the bimodal peaks are more symmetrical.The physical phase analysis of cerium oxide and its precursors prepared by adding PVP as a templating agent showed that PVP had a significant modulating effect on the cerium oxide precursors,and each crystalline surface had different degrees of modulating effect,and the precursor phase was Ce₂（CO₃）₃-8H₂O.In the process of precursor nucleation,the precursor phase is Ce₂（CO₃）₃-8H₂O.In the process of precursor nucleation,PVP adsorbed on the crystal surface and induced the formation of hexagonal lamellar crystals,which eventually agglomerated into flower-like.And the prepared flower-like cerium oxide cerium oxide matches with the standard PDF card.The specific surface area of cerium oxide prepared by adding PVP is 103.7015m²/g,while the specific surface area of cerium oxide prepared without the addition of template agent is 97.3935m²/g.The cerium oxide crystals prepared by adding PVP has a larger specific surface area.The UV absorption area of cerium oxide without the addition of templating agent is UVC and UVB,while the UV area of cerium oxide prepared by adding PVP as templating agent can reach UVA,which can effectively absorb the UV light of conjugated aromatic ring compounds,and has stronger UV absorption,and can be added to cosmetics as sunscreen.The average coefficient of kinetic friction of the prepared cerium oxide was tested and the cost was estimated,which showed that it has lower coefficient of kinetic friction and cost,and is more cost-effective for application.