Photocatalytic property and mechanism studies on acid red 14 by MxOy/ZnTi–layered double hydroxides (M = Fe, Sn, Ce)

• Three transition metal oxides supported ZnTi–LDH composites were synthesized.
• LDH composites with narrow band gap show highly photocatalytic property for AR14.
• LDH composites after AR14 degradation was feasible at least four cycles.
• AR14 molecules were mainly decomposed by the hydroxyl radicals (
• OH).
• The pathways and intermediates for photocatalytic degradation of AR14 were given.

Three transition metal oxides (Fe3O4, CeO2 and SnO2) modified Zn/Ti–layered double hydroxides (LDHs) were successfully synthesized. These materials were characterized by powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), Brunauer–Emmett–Teller (BET) and UV–vis diffuse reflectance spectrum (UV–vis) for the purpose of confirming the formation of good crystal structure. Comparing with original layered double hydroxides, the transition metal oxides modified Zn/Ti layered double hydroxide materials show narrower band gap, larger surface area, smaller pore volume, pore size distribution, and higher removal efficiency for acid red 14 under visible light. The decomposition efficiency of acid red 14 was all over 92% after 120 min. In addition, the thermal regeneration for re-use of layered double hydroxide materials after photodegradation was feasible for at least four cycles (degradation amount still all over 80%). Furthermore, the kinetic parameters, intermediates and possible photocatalytic pathways for acid red 14 decomposed by these transition metal oxides modified Zn/Ti layered double hydroxide materials were also investigated carefully.

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