Browsing by Author "Abreu, Eduardo"
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- 17 α-Ethinylestradiol degradation in continuous process by photocatalysis using Ag/Nb2O5 immobilized in biopolymer as catalystPublication . Lenzi, Giane G.; Abreu, Eduardo; Fuziki, Maria Eduarda K.; Fidelis, Michel Zampieri; Brackmann, Rodrigo; Díaz de Tuesta, Jose Luis; Gomes, Helder; Santos, Onélia A.A. dosThis study describes the application of Ag/Nb2O5 catalysts, suspension and spheres alginate immobilized for the degradation of 17α-Ethinylestradiol (EE2). The techniques used to characterize the photocatalysts were as follows: X-ray diffraction (XRD), N2 adsorption–desorption analysis (BET), point charge zero charge (PZC), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Different catalyst calcination temperatures were studied by keeping the silver metal loading at 5%. Among the operational conditions analyzed were pH, catalyst concentration, the emitting source of radiation and the inlet flow rate (in continuous operation). The results of the experiments performed initially with the catalyst in suspension revealed that the highest catalytic activity in the degradation of EE2 was the 5%Ag/Nb2O5 catalyst calcined at 973 K, which removed 77.7% of the initial pollutant concentration in 120 min of reaction. The immobilization of the catalyst in alginate spheres resulted in a degradation reduction, being able to degrade 69.2% of the initial EE2 in a batch system. In the continuous system, the immobilized catalyst obtained a total degraded of 37.3%, with a flow rate of 10 L·h−1. Catalyst reuse was promising, even dropping the removal, degrading around 27% of the initial EE2 concentration in the third cycle of use.
- Degradation of emerging contaminants: effect of thermal treatment on nb2o5 as photocatalystPublication . Abreu, Eduardo; Fidelis, Michel Zampieri; Fuziki, Maria Eduarda Kounaris; Malikoski, R.M.; Mastsubara, M.C.; Imada, R.E.; Díaz de Tuesta, Jose Luis; Gomes, Helder; Anziliero, M.D.; Baldykowski, B.; Dias, Daniele Toniolo; Lenzi, Giane G.This study describes the use Nb2O5 catalysts – calcined at different temperatures (373–873 K) – in the photo-catalytic degradation reaction of four contaminants of emerging concern: acetylsalicylic acid (ASA), 17α-ethi-nylestradiol (EE2), ibuprofen (IBP) and paracetamol (PAR). The photocatalysts were characterized by different techniques – N2 adsorption/desorption, photoacoustic spectroscopy (PAS), Fourier Transform Infrared (FT-IR) and X-ray diffraction (XRD) – and applied in the photocatalytic degradation tests. Among the tested catalysts, non-calcined Nb2O5 showed the highest photocatalytic activity. The characterization results indicated that this catalyst presented an amorphous (non-crystalline) structure, low band gap and the highest surface area (SBET =182 m2 g-1). A design of experiments (DoE) methodology was applied in order to verify the effects of pH (4–10) and catalyst concentration (0.5–1.5 g L-1) in the four pollutants removal using the non-calcined Nb2O5. Ac-cording to the Experimental Design Analysis, a statistically significant linear effect with a negative coefficient was observed for pH in EE2, IBP and PAR photocatalytic degradation. Tests to verify the influence of the presence compounds together in the degradation reaction of each contaminant, suggested that the photocatalytic degradation of IBP occurs predominantly through the action of radicals O2•-, , with minor contribution from HO•.
- Green magnetic nanoparticles CoFe2O4@Nb5O2 applied in Paracetamol removalPublication . Oliveira, Jéssica; Ribas, Laura S.; Napoli, José Salvador; Abreu, Eduardo; Díaz de Tuesta, Jose Luis; Gomes, Helder; Tusset, Angelo M.; Lenzi, Giane G.; Oliveira, JessícaThis study describes the synthesis of an innovative nanomaterial (patent application number BR 1020210000317) composed of cobalt ferrite functionalized in niobium pentoxide CoFe2O4@Nb5O2 (CFNb), synthesized via green synthesis using tangerine peel extract. The material emphasizes the combination of a magnetic material (which allows for easy recovery after application) with niobium pentoxide (a metal which is abundant in Brazil). CFNb was applied as a catalyst for the paracetamol (PCT) degradation by photocatalysis. The new materials were characterized through surface and pore analysis (S-BET, S-EXT, S-mic, V-mic, and V-TOTAL), photoacoustic spectroscopy (PAS), zero charge point (pHPZC, scanning electron microscopy (SEM/EDS), and X-ray diffraction (XRD). The reaction parameters studied included pH and catalyst concentration. The results indicated that the CFNb nanocatalysts were efficient in the paracetamol degradation, presenting better results in conditions of low pH (close to 2) and low catalyst concentration under irradiation of the 250Wmercury vapor lamp (greater than 28 mW center dot cm(-2)) at 60 min of reaction.