In this study, a TiO 2 catalyst, modified with tungsten oxide (WO 3), was synthesized to reduce its bandgap energy (E g) and to improve its photocatalytic performance. For the catalyst evaluation, the effect of the calcination temperature on the solar photocatalytic degradation was analyzed. The experimental runs were carried out in a CPC (compound parabolic collector) pilot-scale solar reactor, following a multilevel factorial experimental design, which allowed analysis of the effect of the calcination temperature, the initial concentration of amoxicillin, and the catalyst load on the amoxicillin removal. The most favorable calcination temperature for the catalyst performance, concerning the removal of amoxicillin, was 700 • C; because it was the only sample that showed the rutile phase in its crystalline structure. Regarding the loss of the antibiotic activity, the inhibition tests showed that the treated solution of amoxicillin exhibited lower antibacterial activity. The highest amoxicillin removal achieved in these experiments was 64.4% with 100 ppm of amoxicillin concentration, 700 • C of calcination temperature, and 0.1 g L −1 of catalyst load. Nonetheless, the modified TiO 2 /WO 3 underperformed compared to the commercial TiO 2 P25, due to its low specific surface and the particles sintering during the sol-gel synthesis.
Pharmaceuticals are considered among the group of emerging contaminants. Paracetamol is a moderate painkiller, which has been detected in ground and surface water. Photodegradation of paracetamol at a wavelength of radiation of 254 nm with TiO2 nanotubes was studied by UV-spectroscopy, HPLC and measurement of the potential zeta in dependence of the solution pH. The efficiency of the photodegradation of paracetamol (20 mg L−1) was 99% after 100 min exposure. Application of the Langmuir-Hinshelwood equation allowed the evaluation of the rate constant. Non-organic by-products were detected under the conditions of the chromatographic analysis. The photoreaction was faster at pH 6.5, a value at which adsorption was favored, leading to higher efficiency.
La fotodegradación heterogénea solar de ácido dicloroacético (DCA) en un reactor placa plana a escala piloto, con los efectos de concentración inicial de sustrato y carga de catalizador TiO2-P25 fue evaluada. El análisis cinético mostró que la degradación de DCA es controlada por los efectos del proceso fotocatalítico solamente. Además, la concentración inicial del sustrato y la carga de catalizador afectan favorablemente el proceso. No se presentaron degradaciones por fotólisis directa y la adsorción molecular no afectó el desempeño. El seguimiento se llevó usando TOC y ion cloruro. Se obtuvieron conversiones entre 60% y 90% confirmando la efectividad del tratamiento. Las técnicas de seguimiento de TOC y cloruros (Cl-) mostraron la ausencia de intermediarios de reacción. El modelo matemático propuesto garantizó la predicción de los datos experimentales con un coeficiente de correlación de 0.92 y un error medio global de 2.3%.
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