JOAO COUTINHO FERREIRA

JOAO COUTINHO FERREIRA

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Graphene deposited on glass fiber using a non-thermal plasma system
2023 - GOMES, PAULO V.R.; BONIFACIO, RAFAEL N.; SILVA, BARBARA P.G.; FERREIRA, JOAO C.; SOUZA, RODRIGO F.B. de; OTUBO, LARISSA; LAZAR, DOLORES R.R.; NETO, ALMIR O.
This study reports a bottom-up approach for the conversion of cyclohexane into graphene nanoflakes, which were then deposited onto fiberglass using a non-thermal generator. The composite was characterized using transmission electron microscopy, which revealed the formation of stacked few-layer graphene with a partially disordered structure and a d-spacing of 0.358 nm between the layers. X-ray diffraction confirmed the observations from the TEM images. SEM images showed the agglomeration of carbonaceous material onto the fiberglass, which experienced some delamination due to the synthesis method. Raman spectroscopy indicated that the obtained graphene exhibited a predominance of defects in its structure. Additionally, atomic force microscopy (AFM) analyses revealed the formation of graphene layers with varying levels of porosity.
Effective phosphate removal from water by electrochemically mediated precipitation with coffee grounds biocarbon obtained by non-thermal plasma method
2023 - SILVESTRIN, G.A.; GONCALVES, M.H.; GODOI, C.M.; MAIA, V.A.; FERREIRA, J.C.; GUILHEN, S.N.; NETO, A.O.; SOUZA, R.F.B. de
This study investigates the use of biocarbon electrodes, produced from coffee grounds through plasma pyrolysis, in the electrochemically mediated precipitation process for phosphorus removal in a flow reactor. The structural and electrochemical properties of biocarbon were analyzed using X-ray powder diffraction (XRD), Raman spectroscopy, and cyclic voltammetry. The results show that biocarbon consists of both graphene oxide and lignocellulose with surface OH groups that facilitate the breakdown of water, a key step in the electrochemically mediated precipitation process for phosphorus removal. The addition of graphite to the biocarbon paste was found to be necessary to obtain a response from the biocarbon in cyclic voltammetry. The Gr75BC25 electrode achieved higher phosphorus removal rates than other tested electrodes, particularly at low flows, due to the functional groups present in biocarbon enhancing the breakdown of water. However, electrodes with a greater amount of biocarbon exhibit lower rates of phosphorus removal and higher consumption of electrical power, which can be attributed to their higher electrical resistivity. Thus, to optimize its use, it is important to balance the benefits of increased phosphorus removal rates with the trade-off of increased energy consumption and decreased phosphorus removal at higher levels of biocarbon. The results suggest that biocarbon produced from coffee grounds by plasma pyrolysis has the potential to be used as an effective electrode material for electrochemically mediated precipitation processes.
Optimizations on Lithium ion exchange separation and isotopic measurements
2022 - OTOMO, JULIANA I.; GIMENEZ, MAISE P.; ANDRADE, MARIANA N. de; MONTEIRO, LUCILENA R.; NASCIMENTO, LETICIA da S.; BATAGLIA, HENRIQUE; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; BERGAMASCHI, VANDERLEI; COUTINHO, JOAO F.; BUSTILLOS, JOSE O.W.V.
Introduction: The Lithium-7 is of interest for nuclear application, being used for primary cooling of PWR (Pressurized Water Reactor) reactors [1]. An environmentally friendly technique is required to replace the Mercury amalgam technique used worldwide [1,2]. This work aims to present the preliminary results of the development of 7Li separation by ion exchange. Methods: A 120 mm x1.0 cm i.d. glass column filled with Dowex 50W-x16 resin was used. A total of 3.0 liters of 0.2 M CH3COOLi solution percolated the column in order to saturate and displace the formed band of 6Li and 7Li. Fractions were collected every 50 mL, then the resin was washed with 5M HNO3 and ultrapure water. The fractions were filtered and evaporated at 80°C, finally taken up with HNO3 1%. Samples were analyzed by ICP-OES – SPECTRO ARCOS. The fractions were analyzed by ICP-MS, model ELAN 6000 – SCIEX. For isotopic ratio measurement, with the parameters of gas flow of approximately 1.1 L min-1, RF 600 W, gas flow rate 1.2 L min-1, Peak Hopping mode, dwell time 80 and 480 for 6Li and 7Li (respectively), 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: A total of 63 samples were collected from the separation experiment. The Li isotopic ratio measured for each fraction was assessed by ANOVA one-way considering the differences among fractions. A statistical significant difference was observed between the fraction 1 and the remainder fractions and the load solution. The remaining fractions showed an isotopic ratio around the natural abundance (6Li/7Li: 7.59%/92.41% = 0.082). The isotopic ratio of this sample indicated enrichment of 7Li of 0.92% in the fraction number 30. Conclusions: The method of ion exchange with Dowex 50W-x16 resin was efficient on 7Li separation and through ICP-MS method was able to measure the δ 84%₀ enrichment of the 7Li. The isotopic separation procedure via ion exchange is still being studied, however the results are promising.
Sodium interference in lithium isotope ratio analysis by Inductively Coupled Plasma Mass Spectrometry
2022 - ANDRADE, MARIANA N. de; OTOMO, JULIANA I.; GIMENEZ, MAISE P.; NASCIMENTO, LETICIA da S.; NASCIMENTO, HENRIQUE B. do; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; FERREIRA, JOAO C.; BERGAMASCHI, VANDERLEI S.; BUSTILLOS, OSCAR V.
Introduction: Naturally occurring lithium consists of two stable isotopes, 6Li (7.591%) and 7Li (92.409%) and have applications in nuclear technology, pharmaceutical, automotive and geological research. Enriched 7Li isotope in LiOH form has been used as a pH regulator for Pressurized Water Reactor (PWR) reducing corrosion in the primary water circuit [1-3]. The determination of lithium isotopic composition was analyzed by Inductively Coupled Plasma Mass Spectrometry after ion exchange processes, which has been considered a promising technique for the separation of Li isotopes. One of the concerns in ICP-MS analysis is sodium interference. The presence of sodium in the lithium-containing sample has potential implications for the accuracy of isotopic ratio measurements. For this reason, a method is described for the study of sodium interference in 7Li 295,88%₀ and 303,30%₀ enriched solutions. Methods: For this study, the reference standard L-SVEC was used, it has an isotopic abundance of 92.409% for 7Li and 7.591% for 6Li (6Li/7Li ratio = 0.08251) and solutions enriched at 295,88%₀ (6Li/7Li ratio = 0.06661) and 303,30%₀ (6Li/7Li ratio = 0.06810) of 7Li. Concentrations of 50 μg L-1 of lithium were maintained for the solutions used and it was evaluated with the addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium on the enriched samples suffered significant changes in their isotopic ratio. The ICP-MS used for the sample analysis was a PerkinElmer SCIEX Elan 6000. For the isotopic ratio measurement the parameters used was nebulizer gas flow of approximately 0.94 L min-1 , Radio Frequency (RF) 600 W, gas flow rate 1.2 L min-1 , Peak Hopping mode, dwell time 80 and 480 ms for 6Li and 7Li respectively, 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: For this study, 24 samples were analyzed being divided into four sets of samples with 6 samples each set. The sets were composed of samples without addition of sodium and samples with addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium. The first set of samples, composed of the 295,88%₀ enriched sample, had a standard deviation of 3.59✕10-4. The second set of samples, composed of the 303,30%₀ enriched sample, had a standard deviation of 2.63✕10-4. The third and fourth set of samples, composed of aliquots of the L-SVEC standard, obtained a standard deviation of 2.22✕10-4 e 2.54✕10-4, respectively. Showing that the addition of sodium did not significantly interfere in the ratio of lithium isotopes 6 and 7 according to standard deviation. Conclusions: Through the results obtained from the experiment, it was observed that the variation in the ratio between isotopes 6 and 7 of lithium was not significant for the results of analysis in ICP-MS. However, it should be noted that for the purposes of lithium isotope separation processes using ion exchange resins, the interference of sodium in the chromatographic separation needs to be evaluated.
Reforma do etanol para obtenção do hidrogênio utilizando catalisadores de CoCeCu/ZRO2-Y2O3
2022 - FERREIRA, JOAO C.; BERGAMASCHI, V.S.; ARCANJO, G.d.; MORAES, T.S.
Os catalisadores sintetizados neste trabalho foram preparados por complexação metal–quitosana ancoradas em sais de Cobalto, Cobre e Cério com diferentes massas sólidas dos metais de transição na forma de microesferas. Os denominados metais ativos foram suportados em solução de zircônio-ítrio e calcinados a 600 oC. Foram caracterizados por Difração de Raios –X (DRX), Espectrometria Dispersiva de Raios-X (EDS), Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (TEM), Temperatura Programada de Redução (TPR), Analise Termogravimétrica (TG). Os métodos de confecção catalítica foram comparados e avaliados através da reforma a vapor de etanol utilizando um reator tubular de quartzo de leito fixo (5 mm de diâmetro interno) acondicionado com 100 mg de catalisador colocado em um forno vertical sob pressão atmosférica. Foram tratados termicamente a 500 °C, durante 1 h com uma taxa de fluxo do H2 de 30 mL min-1. Água e etanol com relação molar de 1:3 e alimentados e reator usando um sistema com dois aparelhos saturadores com N2 como gás de transporte com fluxo de 20 mL.min- 1. Os reagentes e os produtos foram analisados por um Cromatógrafo a gás (Agilent 7890A).
Preparation and characterization of high-performance Ni-based core-shell catalyst for ethanol steam reforming
2022 - MORAES, TAMARA S.; BERGAMASCHI, VANDERLEI S.; FERREIRA, JOAO C.; SPINACE, ESTEVAM V.
A core–shell catalyst, based on nickel nanoparticles supported on silica nanospheres and surrounded by ceria, was tested for ethanol steam reforming (ESR) reaction (H2O/ethanol: 3/1) under low-temperature conditions (400, 500 and 600 °C) in order to test its stability during the reaction. Two other catalysts of Ni supported in SiO2 and CeO2 were also synthesized to be compared with the core–shell catalyst in the ESR. All catalysts showed excellent activity at 500 and 600 °C with 100% ethanol conversion. Increasing the reaction temperature, carbon deposition on the surface of the catalysts decreases throughout the reaction. The core–shell catalyst showed high coke inhibition capacity in the ESR at 600 °C, without coke formation for at least 100 h of reaction. On the other hand, after 20 h of ESR at 600 °C, Ni–SiO2 and Ni/CeO2 catalysts showed formation of 6.3 and 5.2 mgC/(gcat.h) of coke, respectively. The strong redox capacity of ceria together with the change in catalyst structure due to the deposition of cerium oxide on top of Ni particles led to an excellent ESR activity of this catalyst.
Purification of lithium hydroxide by ion-exchange processes for application in nuclear reactors
2021 - GIMENEZ, MAISE P.; OTOMO, JULIANA I.; FERREIRA, JOAO C.; BERGAMASCHI, VANDERLEI; BUSTILLOS, OSCAR V.
Fractionation lithium isotopes by inorganic ion exchange
2021 - FERREIRA, JOAO C.; SENEDA, JOSE A.; BERGAMASCHI, VANDERLEI S.; GIMENEZ, MAISE P.; BUSTILLOS, OSCAR V.
Core-shell catalysts for ethanol steam reforming reaction
2020 - MORAES, T.S.; FERREIRA, J.C.; BERGAMASCHI, V.S.; SPINACE, E.V.
Hydrogen can be produced from the steam reforming (SR) of biomass-derived liquids such as bioethanol. The SR of ethanol for hydrogen production has several advantages. However, one of the main barriers to the commercialization of this technology is the deactivation of the catalysts due to the formation of carbon. Therefore, the development of catalysts that are stable and resistant to carbon formation is necessary. Several strategies have been used to avoid the deposition of carbon on the surface of the catalysts. Cerium oxide, at high temperatures or in the presence of reducers, can easily change oxidation state to form a non-stoichiometric oxygen deficient oxide. This oxide has a strong tendency to remain in the fluorite structure even after considerable oxygen loss, stabilizing the structure with a high number of oxygen vacancies. Other approach to minimize coke formation is to control the size of metallic particle through modifications in the catalyst structure. According to the mechanism reported in the literature, carbon formation in these reactions are favored in large sizes of metal particle. Therefore, controlling particle size is essential to reduce carbon accumulation on the catalyst surface during ethanol reforming reactions. One strategy for inhibiting the sintering process of metal particles in catalysts is the development of core-shell catalysts. These catalysts feature a metal core covered with an oxide layer, which gives them unique characteristics. The core-shell structure also accelerates the transformation processes of the carbon formed at the metal-oxide interface, favoring the gasification reaction and consequently its elimination in the form of CO2. Das et all have synthesized an innovative sandwiched core-shell structured Ni-SiO2@CeO2 catalyst that showed high activity and stability at dry reforming of biogas with negligible coke formation. The aim of this work is to investigate the performance of the structurally modified Ni-SiO2@CeO2 catalyst in the form of a sandwiched core-shell to inhibit the formation of carbon and increase the stability of the catalysts in the SR of ethanol reaction. This new form of catalyst synthesis has proved very efficient in other reactions but is still very little studied in the ethanol SR reaction. Silica nano-spheres were synthesized by the Stöber method and Ni-SiO2 catalysts were prepared via a Ni-phyllosilicate precursor route. Ni-SiO2@CeO2 will be prepare using the fresh Ni-phyllosilicate spheres that will be coated with a thin layer of CeO2 using a precipitation method. Silica nano-spheres and Ni-SiO2 were calcined at 1273 K for 1 hour with air. Samples were analyzed using transmission electron microscope (TEM) and x-ray diffraction (XRD). SR of ethanol was performed in a fixed-bed reactor at atmospheric pressure. Prior to reaction, catalysts were reduced under pure hydrogen at 923 K for 1 h. The reactions were carried out at 673K and H2O/ethanol molar ratio of 3.0.
Thorium and lithium in Brazil
2019 - OLIVEIRA, GLAUCIA A.C. de; LAINETTI, PAULO E.O.; BUSTILLOS, JOSE O.W.V.; PIRANI, DEBORA A.; BERGAMASCHI, VANDERLEI S.; FERREIRA, JOAO C.; SENEDA, JOSE A.
Brazil has one of the largest reserves of thorium in the world, including rare earth minerals. It has developed a great program in the field of nuclear technology for decades, including facilities to produced oxides to microspheres and thorium nitrates. Nowadays, with the current climate change, it is necessary to reduce greenhouse gas emissions, one of this way is exploring the advent of IV Generation reactors, molten salt reactors, that using Thorium and Lithium. Thorium's technology is promising and has been awaiting the return of one nuclear policy that incorporates its relevance to the necessary levels, since countries like the BRICS (without Brazil) have been doing so for years. Brazil has also been developing studies on the purification of lithium, and this one associated to thorium, are the raw material of the molten salt reactors. This paper presents a summary of the thorium and lithium technology that the country already has, and its perspectives to the future.