Enhanced catalytic performance of a bio-templated TiO2 UV-Fenton system on the degradation of tetracycline

Biomorphic TiO2 was successfully fabricated using maize straw as a template. The morphology and structure analysis revealed that the as-prepared TiO2 retained the original pore morphology of the maize straw material. The framework of the maize-straw-templated TiO2 (T-TiO2) consisted of a cubic grid structure derived from lamellar TiO2 nanosheets. The results of UV-vis diffuse reflectance spectra and PL spectra revealed that the C-doping derived from maize straw template promoted the photoresponse properties of TiO2. Efficient hybrid AOPs (advanced oxidation processes) combining T-TiO2 photo-catalytic oxidation with a Fenton-like reaction for TC oxidation was first investigated, and then, the synergetic degradation effect was discussed in this article. As a result, the synergistic operation of the UV/Fenton/T-TiO2 photocatalytic hybrid process exhibited significant activity towards the degradation of TC (50 mg/L) over a wide pH range of 3.0-9.0 with a remarkably low iron ion dosage (1 mM). Moreover, the degradation kinetics can be well fitted by the pseudo-first order model, where a kinetic constant of 0.09378 min(-1) was achieved, substantially higher than those of the UV/Fenton/N-TiO2 (0.04419 min(-1)), UV/Fenton (0.03343 min(-1)), Fenton (0.0172 min(-1)), UV/H2O2 (0.01412 min(-1)), UV/T-TiO2 (0.00209 min(-1)) and UV (0.00027 min(-1)) systems. The high synergistic effect probably occurred because of (1) the high surface activity of T-TiO2 as photocatalyst, which yielded a remarkably enhanced optical absorption capacity for the lamellar structure, and (2) the efficient reduction of Fe3+ to Fe2+ by the photoinduced electrons from T-TiO2.