http://hdl.handle.net/11422/95 Wed, 08 Apr 2026 03:11:07 GMT 2026-04-08T03:11:07Z http://hdl.handle.net/11422/28426 Title: Avaliação da remoção de Bisfenol-A em um reator de leito móvel com biofilme e dos impactos na nitrificação e degradação de matéria orgânica Author(s)/Inventor(s): Mello, Victor Ferreira de Advisor: Dezotti, Márcia Walquíria de Carvalho Abstract: Bisphenol-A (BPA) is a compound widely used by the plastics industries, and known to be dangerous to health and the environment. Its removal by biological processes is desirable, but needs to be more widely studied. In this context, the treatment of BPA in a synthetic sanitary effluent matrix was evaluated in a moving bed reactor with biofilm (MBBR) - with 6h HRT and 250 m²/m³ - and the impacts caused in the removal of organic matter and ammoniacal nitrogen. by adding BPA to the reactor feed. The operation was divided into two periods, with the maximum removal rates obtained for the effluent feeding without and with BPA. The presence of BPA impacted the processes of removal of organic matter, as observed in the reduction of the maximum rates of volumetric, surface and specific removal by 28.5, 32 and 33.2%, respectively. Nitrogen removal was also impacted by the addition of bisphenol-A, with a decrease in maximum volumetric, surface and specific removal rates by 21, 21.7 and 21.5%, respectively. However, during the continuous operation of the reactor, the average removal of COD and ammonia nitrogen were 84.58% and 97.55%, respectively, before the addition of BPA in the feed, and 79.52% and 97.60 % in the presence of BPA. BPA removal reached values of 72.8% after a period of adaptation of MBBR to Bisphenol-A. This work brings results that are few or inexistent in the literature on the impact of BPA in biological processes of removal of organic matter and ammoniacal nitrogen. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Sun, 01 May 2022 00:00:00 GMT http://hdl.handle.net/11422/28426 2022-05-01T00:00:00Z http://hdl.handle.net/11422/28422 Title: Catalisadores Victor Teixeira: desenvolvimento e avaliação de carbetos bimetálicos e trimetálico de níquel, molibdênio e tungstênio na reação de reforma seca de metano Author(s)/Inventor(s): Barbosa, Renato Dias Advisor: Passos, Fabio Barboza Abstract: Bi and trimetallic carbides (NiMo, NiW and NiMoW) were synthesized, characterized and evaluated as catalysts in dry reforming of methane - DRM (T = 800 °C, P = 1 atm) employing reactional feed with different molar ratios (CH4/CO2 = 1.5; 1.0 and 0.67), simulating the compositions of natural gas reserves contaminated with CO2 or biogas. The NiMoW trimetallic carbide application in DRM is unpublished in the literature and the carbides of NiMo and NiW, scantly investigated, were used in comparison. The catalyst precursors, synthesized by coprecipitation, presented low crystallinities due to their layered turbostratic nickel hydroxides, intercalated by oxometalates of molybdenum and/or tungsten. These precursors were activated by Temperature Programmed Carburization resulting in polycrystalline structures Ni-Mo2C, Ni-WC e Ni-MexC (where Me = Mo+W, x = 1-2). Although bimetallic carbides deactivate in some situations (Ni-Mo2C by oxidation, if CH4/CO2<1; Ni-WC by carbon deposition, if CH4/CO2≥1), the trimetallic carbide NiMoW proved to be active, stable and versatile, even when employed reactional feeds of different molar ratios. Activity and stability of these catalysts in DRM were linked to continuous cycles of oxidation/(re)carburization, where the carbide promotes the activation of carbon dioxide (CO2 → CO +O*) which may lead to their oxidation (Me2C + 5O* →2MeO2 + CO; MeC + 3O* → MeO2 + CO); nickel (Ni0) promotes the methane decomposition (CH4 → C* + 2H2) and the solid carbon formed could lead to oxide (re)carburization (2MeO2 + 5C* → Me2C + 4CO; MeO2 + 3C* → MeC + 2CO). Thus, the pyrolytic carbon deposited over nickel metal sites, the main cause of conventional catalysts deactivation, in these cases, performed a fundamental role in the catalytic activity maintenance, being responsible for the carbothermic (re)carburization of Mo and/or W, partially oxidized by CO2. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Tue, 01 Mar 2022 00:00:00 GMT http://hdl.handle.net/11422/28422 2022-03-01T00:00:00Z http://hdl.handle.net/11422/28419 Title: Nanopartículas de cobalto encapsuladas como catalisador na síntese de Fischer-Tropsch Author(s)/Inventor(s): Smarzaro, Juliana Lemos Advisor: Salim, Vera Maria Martins Abstract: Silica-encapsulated cobalt oxide core-shell particles were prepared by a solvothermal treatment and by the Stöber method. Carbon-encapsulated cobalt oxide yolk-shell particles were also prepared with resorcinol and formaldehyde, using the silica-encapsulated particles as template. In addition, silica-encapsulated cobalt nanoparticles were evaluated as a catalyst for Fischer-Tropsch synthesis at 210 °C and 2 MPa under two different reaction protocols. The samples were characterized by thermogravimetric analysis, inductively coupled plasma optical emission spectroscopy, N2 physisorption at - 196 °C, X-ray diffraction, temperature programmed reduction and electron microscopy. The methods used during the preparation of the silicaencapsulated particles were efficient to obtain uniform particles without agglomeration, while the carbon-encapsulated particles exhibited the coagulation of the shell or nonencapsulated template particles. The silica-encapsulated cobalt nanoparticles were more active in the Fischer-Tropsch synthesis compared to a silica-supported cobalt catalyst. Moreover, the encapsulation of the active phase generated a narrower product distribution and avoided deactivation by sintering. Increasing the silica shell thickness elevated the selectivity towards methane and light hydrocarbons, indicating that the silica pores exerted a confinement effect over the hydrocarbon chain growth or caused diffusional limitations. Furthermore, the use of a protocol that allowed the addition of the feed gas under milder conditions proved the good stability of the encapsulated catalysts within 47 h. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Sun, 01 May 2022 00:00:00 GMT http://hdl.handle.net/11422/28419 2022-05-01T00:00:00Z http://hdl.handle.net/11422/27867 Title: Pós-tratamento de efluente de refinaria proveniente de um biorreator com membranas Author(s)/Inventor(s): Nunes, Paul Antoine Valéry Advisor: Dezotti, Márcia Walquíria de Carvalho Abstract: The effluent treated by an membrane biorreactor (MBR) from an oil refinery has a high salinity (conductivity above 2,000 µS/cm), so that it cannot be used directly as make-up water for cooling tower systems. To allow this use, tertiary treatment with reverse osmosis membranes has been proposed. The evaluation was carried out with the existing filtration bench model. The results showed that the effluent treated by the refinery’s MBR presents an SDI15 of 6.45 with a predominantly organic appearance, demonstrating the need for a pre-treatment to reduce organic matter in the reverse osmosis membrane feed. As for permeate quality, the rejection obtained was 98% in conductivity, with an average of 50.5 ± 8.9 µS/cm, with several analyzed parameters being below the detection limit of the method. As for the permeate flux, the evaluation showed fluxes around 40 L h-1 m-2, but the membrane permeability suffered a decrease from 2.27 to 1.72 L h-1 m-2 bar-1 after tests, which indicated a need for periodic chemical cleaning to maintain permeate production.Também disponível on-line. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Tue, 01 Feb 2022 00:00:00 GMT http://hdl.handle.net/11422/27867 2022-02-01T00:00:00Z