Synthesis of magnetically separable Fe3O4@PANI/TiO2 photocatalyst with fast charge migration for photodegradation of EDTA under visible-light irradiation

• The PANI-TiO2 heterojunctions were synthesized on the surface of Fe3O4 particles.
• The photocatalyst exhibited fast interfacial charge migration ability.
• The photocatalyst exhibited superior magnetic separation characteristic.
• The photocatalyst exhibited enhanced visible-light photoactivity and photostability.

The polyaniline(PANI)/TiO2 composite coating was successfully synthesized on the surface of magnetic Fe3O4 particles by ammonium persulfate induced in situ chemical oxidative polymerization of aniline and in situ synthesis of TiO2. Research showed that this novel Fe3O4@PANI-TiO2 composite photocatalyst exhibited fast charge migration ability and enhanced photoactivity. When the content of anatase TiO2 nanoclusters in the PANI coating was about 0.3 g, the highest photoactivity (k = 1.97 × 10–2 min–1), which is about 4.6 times of the Fe3O4@PANI composite particles, was obtained for decomposing ethylenediaminetetraacetic acid (EDTA) under visible-light irradiation. The enhancement of photoactivity was mainly due to the successful formation of PANI-TiO2 heterojunctions and fast charge migration ability of PANI coating. In photocatalytic process, the photoexcited electrons in PANI could migrate to the conduction band (CB) of anatase TiO2, and the photogenerated holes in the valence band (VB) of anatase TiO2 could directly transfer to the HOMO of PANI. Therefore, the direct recombination of electron-hole pairs would be effectively inhibited, and both the light response and electrical characteristics were improved for the successful formation of the PANI-TiO2 heterojunctions. More importantly, the introduction of the magnetic Fe3O4 particles could satisfy the simple separation and fulfill the regeneration of the photocatalyst after being used.

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