Síntese, caracterização e atividade fotocatalítica na região de luz visível de fotocatalisadores a base titânia comercial (P25 Evonik) e ferro

Heterogeneous photocatalysis is an Advanced Oxidation Process (POA) that involves the activation of a semiconductor by ultraviolet (UV) radiation. To increase process efficiency, impregnate titanium dioxide (TiO2) with metal to thereby extend the absorption band to the visible region (λ = 400 - 700nm) leading to optimization of the process. The energy source for the activation of the catalyst, which in this case was used light (LED) (λ = 495-575 nm, FLC 1W) and a green tubular lamp (TUV 18W) as a visible radiation source, is an efficient light for photocatalysis. The main objectives of this work were to synthesize and characterize photocatalysts based on iron (Fe³⁺) doped with absorption band extended to the visible region and also to evaluate the potential of photocatalytic activity of the catalyst developed using as a pollutant model diethyl phthalate (DEF ). The photocatalytic degradation of the DEF in the aqueous phase was studied under visible light using Ti³⁺ (P25 Evonik) doped with Fe³⁺ being derived from Ferric Chloride (FeCl₃.6H₂O). A complete factorial planning, level 2 and 3 variables, 2³+ 3, totaling 11 trials were carried out in triplicate, considering the effects of the following factors: Temperature, time and molar percentage. Using the wet Method, in the starting concentration of (8, 10 and 12 %) for the preparation of the catalyst. The material was calcined using a 10°C.min⁻¹ ramp the calcination temperatures were (500, 700 and 900°C) for (3, 4 and 5 h). Evonik P25 doped catalysts were characterized by X-ray diffraction (XRD), BET surface area, UV-VIS with diffuse reflectance, infrared with Fourier Transform (FTIR) and Scanning Electron Microscopy (SEM). Fcat-A, Fcat-B, Fcat-C, Fcat-D, Fcat-E, Fcat-F, Fcat-G, Fcat-H,Fcat-I, Fcat-J, Fcat-L, Fcat-M, Fcat-N, Fcat-O and Fcat-P) in which they strongly absorb in the visible region, with band gap of (3,10, 3,11, 3,02, 2,98, 3,20, 3.20, 3.15, 2.00, 2.16, 2.01, 2.07, 2.03, 2.12, 2.06, 2.10, 2.05 eV) the sizes of crystallites (31 , 0.00, 29.00, 31.00, 60.00, 61.00 46.00, 32.00, 68.00, 34.00, 68.00, 34.00, 64.00, 33.00, 32.00 nm). The kinetic model was Langmuir - Hinshelwood (L - H) of the first order generally used in the degradation of organic compounds. From the concentrations studied for the degradation of (0.45, 1.35 and 2.25 mM) DEF, the 0.45 mM concentration showed the best among others, the following Fct-G and Fcat-H catalysts with 0.53 and 0.60 % at 50° C and at 900°C Fcat-H and 0.55 % Fcat-I. For 1.35 mM they obtained 0.61 and 0.80 % whereas Fcat-I and Fcat-J around 0.77 and 0.70% did so for Normalized values, respectively. The photocatalytic degradation process of the DEF in the presence of TiO₂-Fe3³⁺ / UV using green LED light (1 W, 25°C, pH 8, 250 rpm) was not visible for the following catalysts which showed the best overall yields between the catalysts studied Fcat-G, Fcat-I and Fcat-J, yields of (49.4 45.0 and 39.0 %).