Doutorado em Química

URI Permanente para esta coleção

http://repositorio.ufes.br/handle/10/17501

Nível: início
Ano de início: 2014
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=956/a>

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Navegando Doutorado em Química por Autor "Almeida, Luiz Carlos Pimentel"

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    Óxidos Mistos (ZnO/Fe2O3/ZnFe2O4@SiO2) Reciclados a Partir de Baterias de Zn-MnO2 e Rejeitos de Mineração de Ferro Aplicados como Fotocatalisadores, Pseudocapacitores e Sensores Eletroquímicos
    (Universidade Federal do Espírito Santo, 2024-02-02) Magnago, Luma Barbosa; Lelis, Maria de Fátima Fontes; https://orcid.org/0000-0002-4828-4482; http://lattes.cnpq.br/9047743898158654; Freitas, Marcos Benedito José Geraldo de; https://orcid.org/0000-0003-1521-774X; http://lattes.cnpq.br/3485939623614913; https://orcid.org/0000-0002-5271-5572; http://lattes.cnpq.br/4135641802415178; Garcia, Eric Marsalha; https://orcid.org/0000-0002-3731-7568; http://lattes.cnpq.br/8006969980460016; Almeida, Luiz Carlos Pimentel; https://orcid.org/; http://lattes.cnpq.br/0064380963494664; Morais, Verônica Santos de; https://orcid.org/0000-0002-7324-2057; http://lattes.cnpq.br/3680926664416715; Ferreira, Sandra Aparecida Duarte; https://orcid.org/0000-0002-4828-4482; http://lattes.cnpq.br/5439516820869374
    In this study, mixed oxides were prepared using spent alkaline battery anodes, silt fraction (FS), and raw iron mining reject (RB), and applied as photocatalysts, pseudocapacitors, and electrochemical sensors. Characterization analyses revealed that the mixed oxides (FS) and (RB) are composed of SiO2, ZnO, Fe2O3, ZnFe2O4, and are formed by agglomerates of nanoscale particles with a diameter < 200 nm and cubic shapes. For the photocatalytic study, a complete 23 factorial design was conducted to determine the optimal conditions of pH, H2O2 quantity, and the mass of mixed oxide (FS) or (RB) required for the decolorization of 1.56 x 10-6 mol of methylene blue dye (AM) under solar irradiation. The maximum decolorization efficiency was 96 % after 30 min using mixed oxide (FS) and 90 % after 45 min using mixed oxide (RB) with 2.35 x 10-5 mol of H2O2 and 20 mg of the material at pH 3. The efficiencies remained unchanged even after four successive decolorization cycles, and no solution after treatment showed toxicity in the Allium cepa (onion seed) test. In electrochemical studies, mixed oxide (FS) exhibited favorable characteristics for pseudocapacitor application due to its high capacitance (87.16 F g -1 ), energy density (27.24 Wh kg-1 ), power density (524.41 W kg -1 ), and reversibility (93 %). On the other hand, mixed oxide (RB) showed better sensitivity for use as an ascorbic acid (AA) sensor, with a value of 0.23 A mol-1 L cm-2 . This study encompasses recycling of waste and rejects to prepare new materials with multifunctional applications, contributing to environmental sustainability, preservation of raw materials, and the generation of a circular economy.
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    Síntese, caracterização e aplicações de materiais reciclados a partir de baterias íon-Li exauridas
    (Universidade Federal do Espírito Santo, 2018-08-31) Pegoretti, Vitor Cezar Broetto; Freitas, Marcos Benedito José Geraldo de; Lelis, Maria de Fátima Fontes; Ferreira, Rafael de Queiroz; Almeida, Luiz Carlos Pimentel; Profeti, Demetrius
    In this work, cobalt is recycled from a spent lithium-ion battery (LIB) to synthetize high-temperature HT-LiCoO2. In the leaching process, the cathode and anode materials are mixed with sulfuric acid and hydrogen peroxide under stirring and heating. The leaching liquor is filtrated to separate the carbon graphite anode. Cobalt hydroxide is precipitated after the addition of potassium hydroxide to the leaching solution. Cobalt hydroxide and lithium carbonate are the precursor materials for the thermal synthesis of HT LiCoO2 at 800 °C for 5 h. Raman spectroscopyconfirmedthe presence of the ??3¯??phase in HTLiCoO2.Transmission electron microscopy (TEM)analysis showed that the synthesized material has microcracks and defects.The electrochemical behavior of the synthesized material is tested by cyclic voltammetry and cycling tests. The results indicate intercalation and de-intercalation of lithium ions into and from the HT LiCoO2structure. The material presents the highest capacity value of 61.5 mAh g–1for discharge time of 4.4 h in the 4thcycle, and 32.5 mAh g–1in the 15thcycle for discharge time of 2 h. HT LiCoO2is also tested as an electrocatalyst for the oxygen evolution reaction (OER). Cyclic voltammetry and chronoamperometry tests show that the evolution of oxygen starts at 0.35 V accompanied by the formation of Co4+ions. The activation free energy of the reaction calculated using Tafel plot is 28.0 kJ mol-1and electrochemical impedance spectroscopy elucidates an equivalent circuit with a transfer charge resistance of 1.55 O, Warburg impedance of 150.3 O, and constant phase elements of 3.50 and 1.35 mF inside the pores and at the double layer, respectively.A green method was evaluated on route B. A cathodeLiCoxNiyMn1-x-yO2type form aspent lithium-ion battery was leached withmalic acid and the synthesis followed by sol–gelmethod. Three compoundswere prepared varying the synthesis time and the amount of lithium in the reaction medium. CNM10-10h material was obtained after 10 h under muffle furnace at 900 °C with Li:(Co+Ni+Mn)ratio of1.1:1.XRD with Rietveld refinementrevealed that the material is composed of64.3% Li0.31Ni0.5Mn0.5O2(??3¯??)and 35.7% Co3O4(??43¯??).SEM imagesshowedthe presence of octahedral Co3O4particles of approximately 1µmand TEM presented nanorods particles attributed to the lithiated phase. Cyclic voltammetry tests confirmed themultifunctional properties of the mixed oxide, which can be used as pseudocapacitor, catalyst,and non-enzymaticelectrochemical sensor for ascorbic acid determination. The synthesizedmaterial had a specific capacitance of 4.6 F g-1at the 1000thvoltammetric cycleat 10 mV s-1, an ascorbic acid sensitivity of 238.4 µA L mmol-1cm-2,and alinear working range of0.5–5 mmolL-1.CNM10-3h and CNM20-3h materials were obtained after 3 h under muffle furnace. The Li:(Co+Ni+Mn) ratio was 1.1:1 on the first material and 1.2:1 on the second one. XRD with Rietveld refinementrevealed that CNM10-3h material is composed by21.8% of Co3O4(??43¯??) and 78.2%of LiCo0,28Ni0,33Mn0,34O2(??3¯??).CNM20-3h is composed by 14.7 % ofCo3O4(??43¯??) and85.3 % ofLi0.94Co0.25Ni0.34Mn0.41O2(??3¯??).The electrochemical behavior of the synthesized materialswas tested by cyclic voltammetry and cycling tests. The results indicate intercalation and de-intercalation of lithium ions into and from thelithiated phase. Charge/discharge tests under C/10 rate realized on CNM10-3h and CNM20-3h presentedthe highest capacity value of 80and 119 mAh g–1onthe 1stcycle, respectively. Prolonged tests realized in 15 cycles only on CNM20-3h showed the capacity of 39,7 mAh g-1on the last cycle and a 9efficiency of 88,8%. Therefore, the recycling routes proposed in this work are efficient for the production of materials with different technological applications