Química

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http://repositorio.ufes.br/handle/10/17500
Programa de Pós-Graduação em Química

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Navegando Química por Autor "Almeida, Jenifer Rigo"

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    Avaliação da composição química do material ativo do cátodo de baterias de íon-Lítio exauridas após lixiviação com ácido cítrico e análise por ICP OES
    (Universidade Federal do Espírito Santo, 2017-03-27) Almeida, Jenifer Rigo; Freitas, Marcos Benedito José Geraldo de; Athayde, Geisamanda Pedrini Brandão; Carneiro, Maria Tereza Weitzel Dias; Ribeiro, Juliano Souza
    ABSTRACTSpent Lithium-ion batteries (LIBs) are considered hazardous solid wastes due to the presence of metals and organic solvents in their composition, representing waste of non-renewable natural resources and valuable metals when discarded. This work is aimed to provide quantitative data about the chemical composition of cathode active material (CAM)of different spent LIBs in order to monitor variations over the years and assist in material recycling processes. The metals Al, Co, Cr, Cu, Ga,Li, Mg, Mn, Ni, Ti and Zn were determined by inductively coupled plasma optical emission spectrometry (ICP OES) after acid leaching using citric acid (2.0 molL-1) and H2O2(0.25 molL-1) as an environmentally friendly alternative. The optimized conditions for the adaptation of the medium to the analytical curves were:for Al, Cu: HCit curve diluted 10 times without internal standard (IS); For Co, Li, Mn, Ni: HCit curve diluted 500-times without IS; For Ga, Zn: HCit curve diluted 10 times with Y. The analytical procedureemployed reached detection limits of 0.01 mgL-1for Al; 0.20 mgL-1for Co; 0.006 mgL-1for Cr; 0.02 mgL-1for Cu; 0.004 mgL-1for Ga; 0.02 mgL-1for Li; 0.0005 mgL-1for Mg; 0.07 mgL-1for Mn; 0.70 mgL-1for Ni, 0.0005 mgL-1for Ti and 0.007 mgL-1for Zn. The accuracy of the procedure was confirmed by analytical recovery tests with values between 92-113%.The major elements Co (43-67% wt), Li (5.3-6.8% wt), Mn (0.8-8.2% wt), Ni (0.1-11.7% wt) And Al (0.06-3.2% wt) and the minor elements Cr (0.0005-0.002% wt), Cu (0.01-0.05% wt), Mg (0.005-0.02% wt), Ti (0.001-0.07% wt), Ga (0.0009-0.03% wt) and Zn (0.009-0.05% wt) demonstrated that the CAMcomposition may vary according to the capacity and year of manufacture. The older batteries showed the greatest Co and Li levels. The lower capacity batteries were those containing the highest concentrations of Mn and Ni, indicating that Co was replaced. The powder CAM and the residue after leaching were characterized by X-ray diffraction (XRD) yielding the title compound as LiCoO2and can be reused.
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    Ferrita de cobalto reciclada de baterias de íon-Li exauridas e de rejeitos da mineração de ferro: síntese, caracterização e suas aplicações
    (Universidade Federal do Espírito Santo, 2023-04-24) Almeida, Jenifer Rigo; Freitas, Marcos Benedito Jose Geraldo de; https://orcid.org/0000-0003-1521-774X; http://lattes.cnpq.br/3485939623614913; https://orcid.org/0000-0002-6157-6236; http://lattes.cnpq.br/0021205509292342; Sena, Denise Rocco de; https://orcid.org/0000-0002-7581-6560; http://lattes.cnpq.br/7378659077068719; Machado, Marta Albuquerque; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784; Moreira, Thamyres Fernandes Messa; https://orcid.org/0000-0001-7326-8022; http://lattes.cnpq.br/8873474924875435; Ferreira, Sandra Aparecida Duarte
    The objective of this work is to develop solutions for two possible environmental impacts associated with spent Li-ion batteries (LiBs) and reject from iron ore tailing (IOT) from the Mariana environmental accident (Minas Gerais, Brazil). The chemical characterization of starting materials (waste from active cathode material and reject) by inductively coupled plasma optical emission spectrometry (ICP OES) and flame atomic absorption spectrometry (FAAS) showed a recyclable potential of 45.22 ± 0.22 % (w/w) cobalt in LiB and 14.9 ± 1.5 % (w/w) iron in the raw reject from mining. Cobalt ferrites (CoFe2O4−recycled) were produced from recycled Co and Fe by the sol-gel method, which was characterized by X-ray diffraction (XRD). The average crystallite size determined by the Scherrer Equation was 54.4 nm. Scanning electron microscopy (SEM) analysis showed the formation of almost homogeneous large crystalline agglomerates. Energy-dispersive spectroscopy (EDS) performed elemental mapping and showed a mass percentage of 5.65 ± 0.18% (w/w) Co and 13.46 ± 0.38% (w/w) Fe. Co ferrites were applied as catalysts in heterogeneous photo Fenton-type reactions using solar radiation for methylene blue (MB) dye discoloration and as an electrochemical sensor for ascorbic acid. For solar photoFenton heterogeneous reactions, 20.0 mg of catalyst, 0.03 mol.L-1 H2O2, and 50.0 mL of 30.0 mg.L-1 MB dye solution at pH 3.0 were used under solar radiation. CoFe2O4−recycled proved to be an efficient catalyst for methylene blue dye discoloration, with a discoloration efficiency of 95.04 % in just 75 minutes. The pseudo-first-order reaction kinetics were adjusted with a velocity constant of 4.0560 10-2 min -1 and a correlation coefficient of 0.9909. The final disposal solution after catalysis was appropriate for disposal regarding the evaluated inorganic parameters. Since the elements of Al, Co, and Li pose no risks and iron remained below the limit of quantification, Mn, Ni, and Zn, which are regulated elements, were not detected in the final solution. The use of solar radiation during the experimental procedure promoted energy savings. CoFe2O4−recycled presented excellent electrochemical performance. Its use as an electrochemical sensor with a modified working electrode showed an anodic peak at 0.509 V for the oxidation of ascorbic acid (AA) to dehydroascorbic acid, showing an excellent linear correlation between the AA concentration and the current, with a coefficient of 0.9987. This recycled material demonstrated efficiency in two different applications: in the remediation of environmental problems, such as the disposal of textile effluents, and in the use as an electrochemical sensor.