Heterogeneous Photo-Fenton Degradation Of Methylene Blue Under Visible Irradiation By Iron Tetrasulphophthalocyanine Immobilized Layered Double Hydroxide At Circumneutral PH

The strict pH range limits,low visible light utilization and difficulty in separation of catalyst are often outlined as the major drawbacks of the homogeneous photo-Fenton process.To overcome these limitations,the iron tetrasulphophthalocyanine immobilized layered double hydroxides(FePcS-LDH)was synthesized and tested as heterogeneous catalyst for the visible light photo-Fenton degradation of methylene blue(MB)in this work.Response surface methodology based on Box-Behnken design was employed to investigate the effects of process variables on the removal of MB.The main original conclusions of the work are drawn as follows:1.FePcS-LDH were fully characterized by Fourier transform infrared spectra(FTIR),X-ray diffraction(XRD),Scanning electron microscopy(SEM),nitrogen adsorption-desorption isotherms,and diffuse reflectance-UV–vis spectroscopy(DRS-UV–vis).The results of FTIR and XRD reveal that iron tetrasulphophthalocyanine(FePcS)was loaded on the MgAl-layered double hydroxides(MgAl-LDH)successfully;The result of DRS shows that FePcS-LDH can collect a large part of the energy in visible light region;The nitrogen adsorption–desorption isotherms shows that the BET surface area and total pore volume of MgAl-LDH possessed remarkable increase after immobilizing FePcS.2.FePcS-LDH exhibited high photocatalytic activity under visible light irradiation at circumneutral pH.The optimum conditions for MB removal were dye concentration of 10.00 mg/L MB,H2O2 concentration of 10.30 m M and irradiation intensity of 463.50 W.Under these conditions,the maximum MB decolorization efficiency and total organic carbon(TOC)removal efficiency were 99.80% and76.50%,respectively.In addition,the photocatalytic activity of FePcS-LDH was basically kept even after three photocatalytic cycles.3.Free radical capture experiments were used to ascertain the reactive species in the decolorization process of MB,and the primary pathway for the formation of singlet oxygen(1O2),hydroxyl radical(HO·),superoxide radical(O2·-)was deduced and the possible reaction mechanisms for the degradation of methylene blue were proposed.