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Browsing by Author "Paes, Arnaldo Vinicius Dias"

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  • Development of carbon yolk-shell magnetic nanoparticles by a novel eco-friendly approach for the removal of organic micropollutants by catalytic wet peroxide oxidation
    Publication . Paes, Arnaldo Vinicius Dias; Ferrari, Ana Maria; Díaz de Tuesta, Jose Luis
    This work addresses the carbon coating of magnetic nanoparticles based on cobalt ferrites (CoFe2O4) through a traditional method (CoFe2O4@RF), a greener method (CoFe2O4@PG) and their subsequent functionalization in CWPO process. The core of cobalt ferrite nanoparticles was prepared by successive sol-gel methodology, while the carbon-coated materials were obtained through the polymerization of tetraethyl orthosilicate (TEOS), resorcinol-formaldehyde (RF) and phloroglucinol- glyoxylic acid (PG). Subsequently, the materials were submitted to carbonisation under an inert atmosphere of N2 at temperatures of 120 and 400 °C for 1 h for each temperature and 600 °C for 3h. Subsequently, the subsequent removal of silica via washing with NaOH for 16 h. The adsorption isotherms obtained were classified as type IV, typical of materials with mesoporous structure. After the preparation and characterization of the materials, the synthesized catalysts were tested for the removal of paracetamol by wet catalysis with hydrogen peroxide under operating conditions of 80 °C, CPCM,0 = 100 ppm, CH202,0 = 472 mg/L, pH0 = 3.5 and Ccatalyst = 2.5 g L-1, in which over 24 h the concentrations of PCM, H2O2 and aromatic compounds were monitored. All catalysts showed catalytic activity for the removal of PCM by CWPO, in which 100% of PCM removal was obtained for all catalysts after 24 h of reaction time. However, different H2O2 decomposition and PCM removal profiles were observed for the uncoated and coated nanomaterials. Both the carbon-coated catalysts outperformed the results obtained for the uncoated catalyst in terms of H2O2 and PCM decomposition. For the coated materials complete decomposition of PCM was obtained within 6 h of reaction time, while in the same time interval using the uncoated material as a catalyst, only 47% of the initial amount of PCM was degraded from the system. The catalyst coated by the greener method (CoFe2O4@PG) showed a profile of higher selectivity in hydrogen peroxide decomposition and a higher decrease in concentration of aromatic compounds throughout the reaction time. The coated materials were reused in oxidation tests, in which they presented a lower amount of leached iron as well as an increase in catalytic activity, leading to the complete degradation of paracetamol in 4 h of reaction.
    2022Master thesis Open access Show more