Browsing by Author "Carvalho, Pablo Luis Gutierrez"

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    Extraction of yttrium from fluorescent lamps employing multivariate optimization in aqueous two-phase systems.
    (2020) Leite, Daniela da Silveira; Carvalho, Pablo Luis Gutierrez; Almeida, Mariana Ramos; Lemos, Leandro Rodrigues de; Mageste, Aparecida Barbosa; Rodrigues, Guilherme Dias
    This paper presents for the first time the application of aqueous two-phase systems for yttrium recovery from fluorescent lamp residues, a rare earth element with high added value and widely used in the technology in dustry. A multivariate study was carried out, using experimental design, for yttrium extraction employing ATPS using alizarin red as extracting agent, in order to expand the possibilities of the ATPS application in industrial scales. The optimized variables, employing 26–1 fractional design, were pH (3.00–9.00), extracting agent con centration (2.3–23.0 mmol kg−1), tie-line length (TLL), ATPS-forming copolymers (L35 and L64) and electro lytes (Na2SO4 and C6H5Na3O7·2H2O), and mass ratio between top and bottom phases (mTP/mBP = 0.5–2.0). It was observed for the first time, that the metal ions partition in ATPS is mainly influenced by the salt-forming anion species distribution as a function of pH at high TLL values. The extraction of yttrium was optimized in a 23 factorial design with no lack of adjustment and it was able to predict the extraction response with accuracy close to 96%. The optimized conditions of yttrium extraction were applied using a leach liquor from real sample of fluorescent powder. After five extraction steps, 90% of yttrium was selectively recovered.
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    Hydrometallurgical recovery of Zn(II) and Mn(II) from alkaline batteries waste employing aqueous two-phase system.
    (2019) Leite, Daniela da Silveira; Carvalho, Pablo Luis Gutierrez; Lemos, Leandro Rodrigues de; Mageste, Aparecida Barbosa; Rodrigues, Guilherme Dias
    In this study, a greener method for the recovery of zinc and manganese from alkaline batteries waste was developed using Aqueous Two-Phase System (ATPS). ATPS is a liquid-liquid extraction technique. Zn(II) and Mn(II) were extracted using the diluted liquor from samples of spent alkaline batteries, and the experimental conditions were evaluated considering the effects of the following parameters: (i) nature and concentration of the extractants (1-(2-pyridyl-azo)-2-naphthol (PAN), (bis-4-trimethylpentyl) phosphinic acid (Cyanex 272), diphenylthiocarbazone (dithizone, C13H12N4S) and bis-(2-ethylhexyl) phosphoric acid (D2EHPA)); (ii) pH (3.00, 6.00 and 11.0), (iii) ATPS-forming electrolytes (Na2SO4, C6H5Na3O7 or C4H4Na2O6); (iv) ATPS-forming polymers (L35 and L64); and (v) tie-line length (TLL) and mass ratio between top and bottom phases (mTP/mBP). The recovery efficiency was evaluated using the extraction percentage (%E) and separation factor () between Zn(II) and Mn(II). The best conditions for selective extraction of the metal ions were achieved using an ATPS composed by L64 + Na2SO4 + H2O at pH = 3.00, TLL = 41.83% w/w and mTP/mBP = 1 using dithizone as the extracting agent and leach liquor with dilution factor equal to 10. This resulted in a value for separation factor of  = 1.2 × 106, in one extraction stage.
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    Hydrometallurgical separation of copper and cobalt from lithium-ion batteries using aqueous two-phase systems.
    (2017) Leite, Daniela da Silveira; Carvalho, Pablo Luis Gutierrez; Lemos, Leandro Rodrigues de; Mageste, Aparecida Barbosa; Rodrigues, Guilherme Dias
    A new green hydrometallurgical method was developed for the selective extraction of copper and cobalt from spent lithium-ion batteries, using an aqueous two-phase system (ATPS) extraction technique. The method was optimized for the extraction of Cu(II) and Co(II), considering the influence of the following parameters: type and concentration of extractant (1-(2-pyridyl-azo)-2-naphthol (PAN), 1-nitroso-2-naphthol (1N2N), or bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272)); pH (1.00, 6.00, or 11.0); ATPS-forming electrolyte (Na2SO4 or Na3C6H5O7); tie-line length (TLL) of the system; and mass ratio of the top and bottom phases (mTP/mBP). The recovery efficiency was evaluated in terms of the extraction percentage (%E) and the separation factor (S) between copper and cobalt. The best conditions for selective extraction were achieved using an ATPS composed of L64+Na2SO4+H2O,with pH=6.00, TLL=50.3% (w/w),mTP/mBP=1, and PAN as the extracting agent, which resulted in βCu,Co=3.22×102. The method was subsequently applied to a real lithium-ion battery sample, previously leached with HCl and HNO3. Improved separation of copper and cobalt was achieved using successive extraction steps, resulting in βCu,Co=5.40×105. A stripping assaywas also performed, and after a single step, 70.5% of the copper was available for an electrowinning process