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LaFe0.5Co0.5O3 catalyst was synthesized by sol-gel method. The catalytic performance and mechanism of LaFe0.5Co0.5O3 for Orange Ⅱ degradation in the present of H2O2 were studied under the condition of pH=3 and 254 nm UV irradiation. The results showed that the decolorization rate of Orange Ⅱ reached 99. 5% after 60 min reaction, the "first" kinetic rate constant of Orange Ⅱ decolorization was 0. 078 min-1, and the TOC removal efficiency was 81. 60% after 180 min treatment. The results of cyclic experiments and physical and chemical characterization of catalyst showed that LaFe0.5Co0.5O3 had high catalytic ability and good structural stability. Based on the results of free radical quenching experiment and analysis of concentration change of total iron ion, ferrous ion, H2O2 and ·OH, it was proved that the catalytic mechanism of LaFe0.5Co0.5O3 included photo-excitation, hole oxidation, superoxide radical oxidation, photoelectron reduction of iron ion, ferrous ion release, homogeneous Fenton reaction and iron ion readsorption processes. In this system, Orange Ⅱ was degradated through synergistic action of Fenton reaction and photocatalytic reaction. [ABSTRACT FROM AUTHOR]

Based on the analysis of Orange II degradation in the heterogeneous UV-Fenton system with poly-silicate-ferric as catalyst, the accuracy between full-process linear fitting method and piecewise linear fitting method in calculating kinetic constant were compared．A kinetic model of Orange II decoloration was established and verified in terms of catalyst amount and hydrogen peroxide concentration．The results showed that in this heterogeneous UV-Fenton system, the decolorization process of OrangeII could be divided into two stages: rapid and slow decolorization stages using 15min as the dividing line．The rapid decolorization stage was mainly dominated by nitrogen double bonds breaking, and chromophore degradation as a supplement．While the slow decolorization stage was mainly dominated by chromophore mineralization, and nitrogen double bonds breaking as a supplement．The kinetic model based on two-stage linear fitting method had higher accuracy and smaller error in simulation, which could successfully predict Orange II degradation in this heterogeneous UV-Fenton system through theoretical calculation．This study would provide theoretical basis and technical support for the application of heterogeneous UV-Fenton system with poly-silicate-ferric as catalyst． [ABSTRACT FROM AUTHOR]