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.