In order to improve the surface conductivity of α-Fe2O3 used in the photo-Fenton catalyst, the polyaniline (PANI)/α-Fe2O3 heterojunction composite catalysts (FP) were prepared by a simple non in-situ polymerization method, in which the aniline monomer is mixed with the porous rod-like α-Fe2O3 obtained from rod-like β-FeOOH precursors. The effects of the annealing temperatures on α-Fe2O3 and the molar ratio of aniline monomer to α-Fe2O3 on FP were investigated by the removal of methylene blue (MB) under visible light Fenton conditions. The results showed α-Fe2O3 annealed at 500 ℃ (F(T2)) possesses the highest removal of MB among the α-Fe2O3 series, and when the molar ratio of aniline monomer to F(T2) is 2:1, the sample (FP-3) removed 99% of MB within 20 min, which demonstrated that the visible light irradiation could promote the removal of MB by PANI/α-Fe2O3. The enhanced MB removal activity was attributed to the introduction of PANI in α-Fe2O3 can construct type-II heterojunctions, improve the surface conductivity and photogenerated e--h+ separation efficiency of α-Fe2O3 under photo-Fenton conditions, in which the cycle between Fe(II) and Fe(III) was accelerated by visible light in the FP-3 system. The hydroxyl radical (•OH) and cavity radical (h+) are the main reactive species in the photo-Fenton experiment as demonstrated by free radical quenching experiments. In addition, FP-3 composite catalyst showed relatively good cycling performance.

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