Química

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http://repositorio.ufes.br/handle/10/17500

Programa de Pós-Graduação em Química

Centro: CCE
Telefone: (27) 4009 2909
URL do programa: http://www.quimica.vitoria.ufes.br

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Agora exibindo 1 - 9 de 9

Formação de eletrodepósitos de cádmio, síntese e aplicação em fotocatálise de óxido nanoparticulado de cádmio e óxidos de níquel, cádmio, cobalto e ferro a partir de baterias exauridas de Ni-Cd
(Universidade Federal do Espírito Santo, 2016-08-18) Moreira, Thamyres Fernandes Messa; Freitas, Marcos Benedito José Geraldo de; Almeida, Luiz Carlos Pimentel; Lelis, Maria de Fátima Fontes; Athayde, Geisamanda Pedrini Brandão
The recycling of Ni-Cd batteries exhausted is important for environmental, scientific and economic reasonsand canbe performed mainly by pyrometallurgical and hydrometallurgical processes.In this work, were developed hydrometallurgicalroutesfor the recycling of positive and negative electrodes of Ni-Cd batteries.Negative electrode was leached with sulfuric acid (H2SO4) 0.50 mol L-1and the positive electrode in citric acid (C6H8O7) 0.50 mol L-1. The main objective of this work is the synthesis and characterization of metallic cadmium film, cadmium oxide and nickel, cadmium, cobalt and iron oxide. Cadmium metal films were formed with the galvanostatic technique under conditions: current density of -28 mA cm-² and charge density ranging at 11.4 C cm-2and 28.4 C cm-2, current density -56 mA cm-2and charge density of 11.4 C cm-2and 28.4 C cm-2.The maximum deposition efficiency of cadmium reached 84.87% and the reaction of hydrogen evolution occurs in the system while reducing the cadmium. Synthesis of cadmium oxide (CdO) was carried from the thermal treatment of the precursor of cadmium carbonate (CdCO3). The obtained CdO has an average crystallite size of 22.21 nm and was characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The metal oxide synthesized by sol-gel method had mixed composition containing nickel oxide (NiO), CdO, cobalt oxide (Co3O4) and iron oxide (Fe2O3) being called the NiO/CdO/Co3O4/Fe2O3and characterized by FT-IR, XRD, SEM, X-ray spectroscopy for energy dispersion (EDX), TEM and optical emission spectrometry with inductively coupled plasma (ICP OES).The synthesized oxide wasapplied in degradation process of a textile dye Reactive Black V-2B. The CdO oxides and NiO/CdO/ Co3O4/ Fe2O3showed catalytic behavior and efficiencyof degradationdoes not depend on pH.The highest dye degradation efficiency obtained for the CdO was 67.10% and the NiO/CdO/Co3O4/Fe2O386.30% after 480 minutes of analysis
Membranas de Poliamida 11 por Inversão de Fase: um estudo de miscibilidade, morfologia e estrutura
(Universidade Federal do Espírito Santo, 2020-02-18) Lima, Rayanne Penha Wandenkolken; Filho, Eloi Alves da Silva; https://orcid.org/; http://lattes.cnpq.br/8259708288584235; https://orcid.org/; http://lattes.cnpq.br/; Dalmaschio, Cleocir Jose; https://orcid.org/0000000237735786; http://lattes.cnpq.br/5209978120430790; Almeida, Luiz Carlos Pimentel; https://orcid.org/; http://lattes.cnpq.br/
Polyamide 11 (PA11) membranes are prepared by phase inversion (PI) methodology using formic acid (FA) as solvent. The membranes morphology was investigated by Scanning Electronic Microscopy (SEM) analysis. The polyamide film showed a dense and homogenous
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.
Preparação e caracterização de argilas organofílicas e sua aplicação na adsorção de atrazina em água
(Universidade Federal do Espírito Santo, 2017-08-29) Vazzoler, Fabrícia dos Santos D’Agostini; Silva Filho, Eloi Alves da; Barthus, Rosângela Cristina; Almeida, Luiz Carlos Pimentel
Organophilic clays prepared from quaternary ammonium salts stand out as adsorbents for the separation of organic compoundsfrom water. Thus, the purpose of this work was to prepare and characterize three different types of organophilic clays and then to verify the ability of one of these clays to adsorb atrazine in aqueous medium. From the cation exchange process, the naturalclay was modified in organophilic clays, using cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride and dodecyl trimethyl ammonium chloride surfactants. For the clay in natura, the results of the chemical analysis by X-ray fluorescence werecoherent with those of a smectite clay, as well as the result obtained by the cation exchange capacity, which presented a value of 80meq / 100g of clay. The X -ray diffraction data indicate different lamellar expansions for the three organophilic clays obtained when compared to the in naturaclay, proving the presence of quaternary ammonium salts in the interlamellar space. Scanning electron microscopy showed the formation of agglomerations. It was also verified a decrease of the specific surface area demonstrating less accessibility to the lamellar spaces due to the presence of surfactants. The thermogravimetric analyzes were carried out at a constant heating rate up at1000ºC, obtaining a negative variation profile in all the clays, being possible to verify the loss of water and surfactants gradually. The Foster swelling showed strong favoring of adsorption of solvents of nonpolar characteristics, confirming the organophilic character. In addition, the adsorption of atrazine in the chosen organophilic clay was much higher when compared to the in naturaclay, evidencing the potential of using these materials as an alternative to the existing treatments for the removal of organic compounds from water.
Reciclagem do eletrodo positivo de baterias de íon-Li exauridas utilizando ácido cítrico como lixiviador e precursor na formação de eletroquímica de Co(OH)2/Co3O4/LiCoO2 e química de Co3O4/LiCoO2
(Universidade Federal do Espírito Santo, 2016-03-31) Santana, Ívina Langsdorff; Freitas, Marcos Benedito José Geraldo de; Lelis, Maria de Fátima Fontes; Ferreira, Rafael Queiroz; Almeida, Luiz Carlos Pimentel
In this present work, cobalt and lithium from spent lithium ion batteries Samsumg® and HP® was recovered in hydrometallurgical process. Citric acid was leachant and H2O2was reductant agent. Two recycling routes was developed using leaching solution of cobalt and lithium: an electrochemical route; and a synthetic route. On electrochemical route, cobalt oxides (LiCoO2and Co3O4) and hydroxides electrodeposited on nickel substrate using galvanostatic technique. High current density of -0,45 Acm-2used for electrodeposition due to great stability of cobalt and lithium complex. Electrodeposition carried out using charge densities of -250, -300 and -350Ccm-2. Electrochemical recycling route presented low efficiency of electrodeposition (~1,5%) and recycled material, tested as pseudocapacitors, presented irrelevant capacitances (lower than 1 Fg-1). Synthetic recycling route was carried out using a sol-gel method for LiCoO2and Co3O4preparation. To form sol-gel precursor, leaching solution of cobalt and lithium citrate was used. Sol-gel precursor calcined at 250°C, 350 °C, 450 °C and 650 °C formed a mixed cobalt oxides compounds (LiCoO2and Co3O4). Mixed cobalt and lithium oxides tested as catalyst for methylene blue photodegradation presented good catalytic activity. Mixed cobalt oxides calcined at 450 °C degraded 90% of methylene blue after 10 hours and 100% after 24 hours of photocatalysis. Sol-gel precursor calcined at 850 °C formed only LiCoO2. Electrochemical properties of recycled cobalt and lithium oxide were studied using cyclic voltammetry. Recycled LiCoO2is a promising material for lithium ion batteries cathodes. The contribution of this work is that it presents a means to produce valuable materials having electrochemical and catalytic properties from recycled batteries trough a spent lithium ion batteries without polluting the environment
Síntese de NiFe2O4 a partir do níquel reciclado de baterias Ni-MH e suas aplicações multifuncionais como um catalisador em processos foto Fenton e como um pseudocapacitor eletroquímico
(Universidade Federal do Espírito Santo, 2018-03-16) Magnago, Luma Barbosa; Lelis, Maria de Fátima Fontes; Freitas, Marcos Benedito José Geraldo de; Athayde, Geisamanda Pedrini Brandão; Almeida, Luiz Carlos Pimentel
In this study, a co-precipitation method was used for the synthesis of undoped ferrites (Fe2O3/Fe3O4-R) and nickel-doped ferrites from nickel reagents (NiFe2O4-R) and from nickel recycled from spent nickel–metal hydride (Ni-MH) batteries (NiFe2O4-B). Ferrite structure and composition were confirmed by X-ray diffraction (XRD), energy dispersive X-ray (EDX) and inductively coupled plasma optical emission spectrometry(ICP-OES). Scanning electron microscopy (SEM) showed agglomerated particles of different sizes and shapes and the transmission electron microscopy (TEM) revealed spherical particles of 50 nm. Ferrites are a multifunctional material that can be used as a catalyst and pseudocapacitor. The catalytic properties of ferrites were analyzed by measuring the decolorization of methylene blue (MB) in a photo-Fenton process under solar radiation. The experimental design ranked ferrites in the following order of MB decolorization efficiency: NiFe2O4-B = NiFe2O4-R > Fe2O3/Fe3O4-R. Using NiFe2O4-B, MB solutions were decolorizedwith more than 90% efficiency in 90 min. ICP-OES analyzes of the solution contained indetected concentrations of (0.00057 ± 0.00067) mg L-1of nickel ions and undetected concentration of ironions. The concentrations of nickel and iron ions arelower than the standard effluent release concentrations indicated CONAMA resolution 430/2011. NiFe2O4-B ferritedoes not transfer metals ions present in its composition to the solution. Analysis of the MB solution by ion chromatography after the NiFe2O4-B-catalyzed decolorization showed the presence of formic, acetic, and propionic acids.Pseudocapacitive properties, analyzed by cyclic voltammetry, showed that NiFe2O4-B have higher charge efficiency (84.3%) when compared with NiFe2O4-R (65.5%) and Fe2O3/Fe3O4-R (57%) after 1000 cycles. Ferrite NiFe2O4-B is an efficient catalyst for MB degradation andas pseudocapacitor
Síntese e caracterização de ferritas não dopadas e dopadas com Mn a partir de baterias Zn-MnO2 exauridas e suas aplicações catalíticas
(Universidade Federal do Espírito Santo, 2017-03-28) Barrada, Renan Vicente; Lelis, Maria de Fátima Fontes; Freitas, Marcos Benedito José Geraldo de; Silva Filho, Eloi Alves da; Almeida, Luiz Carlos Pimentel
In this current research, non-doped ferrites (Fe2O3/Fe3O4) and ferrites doped with manganese (MnFe2O4(R)) were synthesized using commercial reagents (MnFe2O4(B)) and manganese recovered from spend Zn-MnO2 batteries. The cathode of spend Zn-MnO2 batteries consists mainly of MnO2 and Mn3O4 according to X-ray diffraction (XRD) analysis. Analysis by inductively coupled plasma optical emission spectrometry (ICP OES) detected the presence of zinc from the anode of the batteries. The cathode manganese was leached with 0.5 molL-1 nitric acid and used as a dopant in the synthesis of MnFe2O4(B) ferrites. The synthesized materials presented characteristics of MnFe2O4, according to X-ray diffraction (XRD). The ferrites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the micrographs it was verified that the materials presented particles and agglomerates with varied and irregular geometry in nanoscale. By X-ray dispersive energy (EDS) spectrometry analysis coupled to the SEM, the composition of the synthesized ferrite particles could be analyzed. It obtained the peaks of Fe and O in the sample of Fe2O3/Fe3O4, and Fe, Mn and O in the samples of MnFe2O4(R) and MnFe2O4(B). The chemical composition of ferrites was determined by dichromatometry for iron and flame atomic absorption spectrometry (F AAS) for manganese and obtaine that 66.6% of Fe to Fe2O3/Fe3O4, 56.6% of Fe and 11.5% Mn for MnFe2O4(R), and 61.5% Fe and 4.5% Mn for MnFe2O4(B). The ferrites were catalytically evaluated in the discoloration of the methylene blue dye through the heterogeneous photo Fenton process, obtaining 15.6%, 98% and 92% of dye discoloration using Fe2O3/Fe3O4, MnFe2O4(R) and MnFe2O4(B) respectively, in 120 minutes of reaction.
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
Uso da RMN no estudo da despolimerização de poliuretano rígido
(Universidade Federal do Espírito Santo, 2019-03-26) Maioli, Juliana Proliciano; SILVA FILHO, Eloi Alves da; Cunha Neto, Álvaro; Freitas, Marcos Benedito José Geraldo de; Almeida, Luiz Carlos Pimentel
Polyurethanes (PUs) have been widely used in several trade sections. Thereby, large amounts of waste are produced and need to be correctly disposed off. Research on this theme has been helping industries to apply recycling processes that are cheap and efficient. In this work, the glycolysis of a rigid PU was performed using different catalysts. The catalysts used was: a tensoactive (CTAB), the NaOH, two ionics liquids (1-butyl-3-methylimidazole trichloromanganate and 1-butyl-3-methylimidazole trichlorozincate), and four Niobium salts (niobium pentoxide, niobium oxidehydrated, niobium pentachloride and niobium ammoniacal oxalate). 1H NMR technique was used to obtain the rate of PU depolymerization. Also was used the technique diffusion ordered spectroscopy 1H NMR (DOSY-NMR) that assisted in the identification composition of the mixture of products. In the glycolysis, glycerol (GCL) and diethylene glycol (DEG) were tested as glycolysis agents. The PU was synthesized to be free of additives in the depolymerization process, and its characterization was performed using infrared spectroscopy (FTIR) and 1H NMR spectroscopy analyses. The conversion rate provides information about which catalyst has the better catalytic activity. The use of NaOH as a catalyst presented conversion rate of 100 % in 30 min of reaction, as is already known in the literature, and the DOSY-NMR spectrum provided information about products that didn’t perceptible only by 1H NMR spectrum. Ionic liquids (LIs) as catalysts, presented conversion near of 80 % in 1h of reaction, which can be improved by modifying the reaction conditions. To determine the composition of the mixture of products in the depolymerization reaction, diffusion ordered spectroscopy 1H NMR (DOSY-NMR) was used. The Niobium salts had non-catalytic behavior, because they showed conversion rate lower than uncatalyzed reaction. DOSY-NMR indicated a complex mixture of reaction by-products, differently from the 1H NMR data, which indicated the formation of a simple diamine-terminated by-product.

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