The topological diversity of lithium-boron imidazolates LiB(imid)4 was studied by combining topological enumeration and ab initio DFT calculations. The structures based on zeolitic rho, gme and fau nets are shown to be stable and have high total hydrogen uptake (6.9–7.8 wt.%) comparable with that of MOF-177. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Hydrogen is an appealing energy carrier for clean energy use. However, storage of hydrogen is still the main bottleneck for the realization of an energy economy based on hydrogen. Many materials with outstanding properties have been synthesized with the aim to store enough amount of hydrogen under ambient conditions. Such efforts need guidance from material science, which includes predictive theoretical tools. Carbon nanotubes were considered as promising candidates for hydrogen storage applications, but later on it was found to be unable to store enough amounts of hydrogen under ambient conditions. New arrangements of carbon nanotubes were constructed and hydrogen sorption properties were investigated using state-of-the-art simulation methods. The simulations indicate outstanding total hydrogen uptake (up to 19.0 wt.% at 77 K and 5.52wt.% at 300 K), which makes these materials excellent candidates for storage applications. This reopens the carbon route to superior materials for a hydrogen-based economy. Zeolite imidazolate frameworks are subclass of MOFs with an exceptional chemical and thermal stability. The hydrogen adsorption in ZIFs was investigated as a function of network geometry and organic linker exchange. Ab initio calculations performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF framework. Subsequently, GCMC simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions. The best of these materials (ZIF-8) is found to be able to store up to 5 wt.% at 77 K and high pressure. We expected possible improvement of hydrogen capacity of ZIFs by substituting the metal atom (Zn 2+) in the structure by lighter elements such as B or Li. Therefore, we investigated the energy landscape of LiB(IM)4 polymorphs in detail and analyzed their hydrogen storage capacities. The structure with the fau topology was shown to be one of the best materials for hydrogen storage. Its total hydrogen uptake at 77 K and 100 bar amounts to 7.8 wt.% comparable to the total uptake reported of MOF-177 (10 wt.%), which is a benchmark material for high pressure and low temperature H2 adsorption. Covalent organic frameworks are new class of nanoporous materials constructed solely from light elements (C, H, B, and O). The number of adsorption sites as well as the strength of adsorption are essential prerequisites for hydrogen storage in porous materials because they determine the storage capacity and the operational conditions. Currently, to the best of our knowledge, no experimental data are available on the position of preferential H2 adsorption sites in COFs. Molecular dynamics simulations were applied to determine the position of preferential hydrogen sites in COFs. Our results demonstrate that H2 molecule adsorbed at low temperature in seven different adsorption sites in COFs. The calculated adsorption energies are about 3 kJ/mol, comparable to that found for MOF systems. The gravimetric uptake for COF-108 reached 4.17 wt.% at room temperature and 100 bar, which makes this class of materials promising for hydrogen storage applications.

Disponibiliza??o do conte?do parcial, conforme Termo de Autoriza??o no trabalho. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2016-12-21T19:05:57Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wbiratan_cesar_macedo_oliveira_parcial.pdf: 128173 bytes, checksum: 9c9067430cf3b7ef9b7952182484b258 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-01-31T14:19:01Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wbiratan_cesar_macedo_oliveira_parcial.pdf: 128173 bytes, checksum: 9c9067430cf3b7ef9b7952182484b258 (MD5) / Made available in DSpace on 2017-01-31T14:19:01Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wbiratan_cesar_macedo_oliveira_parcial.pdf: 128173 bytes, checksum: 9c9067430cf3b7ef9b7952182484b258 (MD5) Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Neste trabalho foi estudado o comportamento de extra??o do lant?nio em sistemas aquosos bif?sicos (SAB) e foi desenvolvido um novo m?todo hidrometal?rgico ambientalmente seguro para a extra??o seletiva de La a partir de lixiviado de baterias NiMH. O comportamento de extra??o do La foi avaliado verificando a influ?ncia dos seguintes par?metros: presen?a e concentra??o de diversos agentes extratantes (Alaranjado de xilenol, 1-(2-piridilazo)-2-naftol, Ditizona, 8-hidroxiquinolina, e 1,10-fenantrolina); pH (3,00, 6,00 e 9,00); eletr?lito (Li2SO4, Na2SO4, MgSO4, Na2C4H4O6 e Na3C6H5O7 ) e pol?mero (L64 e PEO1500) formadores do sistema. A efici?ncia de recupera??o foi avaliada atrav?s da an?lise da porcentagem de extra??o (% E) e as melhores condi??es de extra??o do analito foram obtidas no SAB formado por PEO1500 + Li2SO4 + H2O, pH = 6,00; empregando o extratante 1,10-fenantrolina, atingindo um valor m?ximo de %E = 74,1 %. Na sequencia o m?todo foi aplicado a um lixiviado de bateria NiMH. Os terras raras foram precipitados mediante ajuste de pH (2,50) e posteriormente solubilizado em solu??o de H2SO4 0,1 M. Ap?s 3 etapas sucessivas de extra??o foram obtidos altos valores de fator de separa??o (S) entre o analito e os concomitantes met?licos (SLa,Co = 6.3 x 103, SLa,Ni= 2,55 x 104, SLa,Fe= 1,15 x 103 and SLa,Ce= 30,9). Al?m disso, foi realizado um ensaio de stripping no qual 88,5% de La, em uma ?nica etapa, foi redisponibilizado sob a forma i?nica na FI para uma poss?vel etapa posterior de eletrodeposi??o. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / In this work was investigated the extraction behavior of lanthanum in the aqueous two-phase system (ATPS) and new environmentally safe hydrometallurgical method was developed for the selective extraction of La from NiMH battery leachate. The extraction behavior of La was evaluated verifying the influence of the following parameters on the metals extraction: presence and concentration of the several extractants 1-(2-piridil-azo)-2-naphtol, dithizone, 8-hydroxyquinoline, 1-10 phenanthroline and xylenol oragne; pH (3.00, 6.00 and 9.0); ATPS-forming electrolyte ((Li2SO4, Na2SO4, MgSO4, Na2C4H4O6 e Na3C6H5O7); ATPS-forming polymer (L64 or PEO1500). The recovery efficiency was evaluated through analyzing the extraction percentage (%E) and the best conditions for analyte extraction were achieved for the PEO1500 + Li2SO4 ATPS, pH = 6.00, using 1-10 phenanthroline as extractant agente (%E = 74,1 %). In the following section, the method was applied to a real NiMH battery leachate. The rare earths were precipitated by pH adjustment (2.50), which was solubilized in 0,1 M H2SO4 solution. After 3 steps of successive extractions it was possible to obtain high separation factor (S) values between the analyte and mettalic concomitant (SLa,Co = 6.3 x 103, SLa,Ni = 2,55 x 104, SLa,Fe = 1,15 x 103 and SLa,Ce = 30,9). Moreover, a stripping assay was carried out and after one single step, 88.5% of lanthanum was available to a possible electro winning step.

Data de aprova??o ausente. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-03-29T18:49:58Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wagner_barbosa_souza.pdf: 2617971 bytes, checksum: 3d7e6b01cafdb0a61d93af504071663c (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-04-24T16:36:52Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wagner_barbosa_souza.pdf: 2617971 bytes, checksum: 3d7e6b01cafdb0a61d93af504071663c (MD5) / Made available in DSpace on 2017-04-24T16:36:52Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) wagner_barbosa_souza.pdf: 2617971 bytes, checksum: 3d7e6b01cafdb0a61d93af504071663c (MD5) Previous issue date: 2016 / Com o avan?o exponencial da ind?stria de eletr?nicos, o consumo destes produtos tamb?m est? crescendo largamente. Com isso, os descartes destes equipamentos tamb?m crescem na mesma propor??o. Por ano, no mundo, estima-se que mais de 25 milh?es de toneladas de lixo eletr?nico sejam descartadas. Neste trabalho foi desenvolvido um novo m?todo hidrometal?rgico ambientalmente seguro para a extra??o seletiva de cobre, n?quel e prata provenientes de res?duos de placas de circuito impresso (PCI), empregando Sistemas Aquosos Bif?sicos (SAB) como t?cnica de extra??o. O comportamento de extra??o dos ?ons met?licos Cu (II), Ni(II), Fe(III) e Ag(I)em SAB formado por copol?mero tribloco L64 + MgSO4 + H2O foi avaliado para a otimiza??o do m?todo, verificando a influ?ncia dos seguintes par?metros experimentais sobre a extra??o dos analitos: valores de pH do SAB (3,0; 6,0; 9,0 e 11,0); natureza e concentra??o dos agentes extratores 1-(2-piridil-azo)-2-naftol (PAN) para os estudo de extra??o do Cu(II), 1-nitroso-2-naftol (1N2N) e dimetilglioxima (DMG) para a extra??o do ?on Ni(II), tiocianato (SCN) e ditizona (Dz) para a extra??o da Ag(I). A efici?ncia de recupera??o seletiva dos metais foi avaliada por meio da an?lise da porcentagem de extra??o (%E) e do fator de separa??o (S) entre os ?ons de interesse. As melhores condi??es para extra??o seletiva foram: PAN [3,5 mmol.Kg-1] em pH = 6,0 em 6 etapas consecutivas para separa??o do Cu(II), DMG [5,00 mmol.Kg-1] em pH = 9,0 para o Ni(II) e SCN[5,20 mmol.Kg-1] em pH = 9,0 para a Ag(I) . Em todas as situa??es foram obtidos valores de fator de separa??o(S) entre o analito e os concomitantes met?licos maiores que 103. As condi??es ?timas obtidas foram aplicadas ao lixiviado de PCI para a extra??o de cobre, n?quel e prata de forma sequencial, obtendo-se altos valores de S entre o analito e os concomitantes met?licos (SCu,Ni= 1,46 x 103, SCu,Fe= 1,55 x 104, SCu,Ag= 1,59 x 104, SNi,Fe= 3,27 x 104, SNi,Ag= 3,47 x 104 eSAg,Fe= 4,80 x 103).Ap?s a extra??o de cada metal foi realizado um estudo de stripping em uma ?nica etapa, onde 89,5%, 92,5% e 82,5% de Cu(II), Ni(II) e Ag(I), respectivamente foram disponibilizados para a etapa de eletrodeposi??o. Portanto o m?todo utilizando SAB se mostrou eficiente e dentro dos princ?pios da qu?mica verde, pois utiliza componentes at?xicos, biodegrad?veis e recicl?veis e de r?pida separa??o de fases sem a forma??o de emuls?es est?veis. Sendo um m?todo alternativo para a extra??o liquido ? liquido tradicional. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, [2016]. / With the exponential advancement of electronic industry, the consumption of these products is also growing wide. With this, the drops of this equipment also grow at the same rate. A year in the world, it is estimated that more than 25 million tons of electronic waste are disposed.This work developed a new environmentally safe hydrometallurgical method for the selective extraction of copper, nickel and silver from waste printed circuit board (PCB) using Aqueous Two-Phase Systems (SAB) as extraction technique. The extraction behavior of metal ions Cu (II), Ni (II), Fe (III) and Ag (I) SAB formed by tri-block copolymer L64 + MgSO4 + H2O was evaluated for the optimization of the method by checking the influence of the following experimental parameters on the extraction of analytes: the SAB pH (3.0, 6.0, 9.0 and 11.0); nature and concentration of agents extractors 1- (2-pyridyl-azo) -2-naphthol (PAN) Cu for the extraction method (II), the 1-nitroso-2-naphthol (1N2N) and dimethylglyoxime (DMG) for ion extraction Ni (II), thiocyanate (SCN) and dithizone (Dz) for the extraction of Ag (I).The selective metal recovery efficiency was evaluated by the percentage extraction analysis (% E) and separation factor (S) between the ions of interest. The best conditions for selective extractions were NAP [3,5 mmol.Kg-1] at pH 6.0 in 6 consecutive stages for separation of Cu (II) DMG [5.00 mmol.Kg-1] pH = 9.0 for Ni (II) and SCN [5,20 mmol.Kg-1] at pH = 9.0 for Ag (I). In all cases they were obtained separation factor values (S) between the analyte and the larger metal Concomitant 103. The obtained optimum conditions were applied to the PCI leached copper extraction, nickel and silver sequentially, yielding if high S values between the analyte and the metal concomitant (SCU, Ni = 1.46 x 103, SCU, Fe = 1.55 x 104, SCU, Ag = 1.59 x 104, SNI, Fe = 3.27 x 104, SNI, Ag = 3.47 x 104 and SAg, Fe = 4.80 x 103).After extraction of each metal it was made a study stripping in one step, where 89.5%, 92.5% and 82.5% Cu (II), Ni (II) and Ag (I), respectively, were available for the electroplating step. Therefore, the method using BSA was efficient and within the principles of green chemistry, because it uses non-toxic, biodegradable and recyclable and fast phase separation without the formation of stable emulsions components. As an alternative method for liquid - liquid extraction traditional.

No description available.

The Pilbara region of Western Australia hosts the Hamersley Province, an area of abundant iron ore resources located in the lower Hamersley Groups, Brockman and Marra Mamba Iron Formations. This study consists of a geotechnical and a geochemical and mineralogical investigation into the Banded Iron Formation (BIF) and shale deposits of the lower Hamersley Group that reside in the pit walls of RTIO mines in Western Australia. Areas throughout Tom Price, Paraburdoo, Marandoo and West Angelas iron ore mines are geotechnically investigated for rock mass conditions through the use of the Slope Mass Rating (SMR) classification system and through point load and slake durability testing. Selected samples from these areas were then geochemically and mineralogically tested by X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and microscopic analysis, to determine the geochemical and mineralogical changes of BIF and shale as they alter and weather through hypogene and supergene alteration and Recent weathering. It was found that the most efficient method for determining the alteration and/or weathering of lower Hamersley Group BIF and shale deposits was by the use of a chemical alteration index, calculated from enriched and depleted major elements in the BIF and shale as they alter and weather. It has been suggested here that this Pilbara Iron alteration index can be calculated efficiently and effectively from geochemical testing in intervals down boreholes throughout future or developing open pit mines to assist in estimating slope stability conditions. It is also suggested that many boreholes should be analysed in section or in 3D space to create cross sections or block models showing the varying extent of alteration and weathering throughout the area being studied. From the geotechnical investigation, it was found that the weakest region, in terms of pit slope stability, were the highly and extremely altered and/or weathered regions with Pilbara Iron alteration indices of between 61 and 80, and 81 and 100, respectively. If these zones are identified, slope stability analysis can be focused on these geotechnically vulnerable areas. Slope stability analysis should be completed by using a suitable technique, such as by the use of SMR, which, along with other risk identification measures, will identify potentially unstable areas and suggest the required course of action. Further hazard and risk analysis should be undertaken in potentially unstable areas and remedial measures undertaken as appropriate. Thereby, the Pilbara Iron alteration index can be used in the Hamersley Province as a predictive tool for pit slope stability.