The Analysis Of The Perovskite-carbon Nitride Composites And Its Application For Fenton-like Treatment Of Wastewater

In this thesis,the performances of graphite carbon nitride?g-C₃N₄?and perovskite oxide for the removal of rhodamine B?RhB?in wastewater were studied,based on the achievements of g-C₃N₄ and perovskite oxides reported in literature.The following four works were conducted:First,g-C₃N₄ was synthesized for photo-fenton catalytic removal of RhB,using guanidine hydrochloride,urea and urea-melamine mixture as precursors.The results showed that sample prepared using guanidine hydrochloride or urea as precursor has high surface area and exhibited good activity for RhB removal,while that prepared using the urea-melamine mixture has better crystalline structure,but large particle size and low surface area,thus exhibited poor activity.Second,LaFe_xCo_1-xO₃ catalysts were prepared by sol-gel method for photo-fenton catalytic removal of RhB.The results showed that the substitution by Co atoms improves the surface area,and the catalyst reaches the best activity at Co percentage of 50%(i.e.LaFe_0.5Co_0.5O₃).This is because the sample has appropriate oxidation capacity,and it will not over-oxidize H₂O₂ to H₂O.Third,LFO@CN composites were in-situ prepared by one-pot thermal condensation of the precursors of carbon nitride and perovskite and used for photo-fenton catalytic remove RhB.X-ray diffraction showed that Fe and La are existed as FeC₂O₄ and La₂O₂CN₂,which can yield synergistic effects,improve the photogenerated electrons-holes separation efficiency.Thus,the catalyst exhibited excellent activity for RhB elimination.The best activity was achieved at the molar ratio of precursors of perovskite oxide to carbon nitride equals 1:16.Moreover,the catalyst is recyclable and is active for the removal of other organic dyes including methylene blue and neutral red.Last,LaFeO₃@g-C₃N₄ composites were prepared with a two-step method,by synthesis of LaFeO₃ and g-C₃N₄ in advance and then hydrothermal treatment of them at high temperature.Effects of LaFeO₃ preparation method?i.e.,precipitation,templating and sol-gel method?on the catalytic performances of LaFeO₃@g-C₃N₄ for photo-fenton catalytic removal of RhB were investigated.The results showed that the composites retained the original structure of perovskite and carbon nitride,and that the LaFeO₃ prepared by sol-gel method,with theoretical mass percentage of 90%,i.e.,LaFeO₃@g-C₃N₄-10%has the best activity for the reaction.