Dissertations / Theses on the topic 'Gibbsite'
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Fleming, Sean D. "Computer modelling of gibbsite crystallization." Curtin University of Technology, School of Applied Chemistry, 1999. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10273.
Full textwere made. Different crystal habits were constructed by applying a range of defect surface coverage values to each of the faces appearing in the morphology. The resulting defect morphologies were in excellent agreement with crystal habits commonly observed by experimentalists. Also, the work provided an explanation for the earlier underestimation of the prismatic faces. Chapter Six documents molecular simulations of solutions containing the major species known to be present in industrial and experimental Bayer liquors. The structuring in two solutions, one containing sodium hydroxide and the other potassium hydroxide, was probed by constructing graphs of the radial distribution functions. These plots indicated that a significant degree of ion pairing was occurring between the alkali metal cations (Na+ and K+) and the aluminate monomer ([Al(OH)4(subscript)]-). Furthermore, these cations were found to be acting as 'bridges' which stabilize multiple aluminate monomers, allowing them to form clusters. This data was used to assist in explaining vibrational spectra, and to postulate that clustering may be the origin of the fine particle suspensions noted during the induction period.
Gückel, Katharina. "Structural analysis of ternary actinyl(V/VI) sorption complexes on gibbsite." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-126300.
Full textMitchell, Scott Christian. "An Improved MUSIC Model for Gibbsite." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd831.pdf.
Full textChiang, Yu-Lun. "Antisolvent gibbsite crystallisation from synthetic Bayer liquor." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/8927.
Full textThe current Bayer precipitation of gibbsite is notoriously slow and is considered to be the rate limiting step of the Bayer process. The present industrial reactor configuration involves precipitating gibbsite inside a series of large stainless steel agitated vessels due to the slow precipitation kinetics of gibbsite from pregnant Bayer liquor. The scope of this study is to investigate the effectiveness of using water as an antisolvent to increase the overall gibbsite yield and the associated particle behaviours under isothermal conditions. The experiments were performed in a series of batch experiments which were divided into two subsets. Firstly, the effect of different caustic concentrations present in the anti solvent on gibbsite yield was tested. Secondly, the effect of different seed loading (50 and 100 grams seeds per liter of synthetic liquor) on aggregation and fines formation were investigated. All batch experiments were conducted isothermally at 80°C under a closed system using a baffled stainless steel 316 agitated vessel. The experimental results indicated water to be a feasible medium for the isothermal antisolvent crystallisation of gibbsite from synthetic pregnant Bayer liquor. It was found that the extent of overall gibbsite yield exhibits a power law correlation to the change in the antisolvent caustic concentration with R2 ~1 (R2 = 0.99974). This finding is important as the regressed curve will be used to correlate gibbsite yield as a function of anti solvent purity. From the seed loading experiments, an Increase In seed loading under constant temperature and initial liquor supersaturation resulted in an overall decrease in product particle size due to a rise in inter-particulate attrition. However, crystal growth was not dominant during any period of the experiments with aggregation being more prominent for the system with the lower seed load. Gibbsite morphology determination from SEM revealed hexagonal solids which, in the presence of a higher seed loading indicated signs of fracture due to attrition. Quantitative evidence of this mechanism is shown USIng the discretised population balance method by Bramley et al. (1996) with the aid of the computational technique developed by Hounslow (2005) in Mathematica. Results generated using this method show decreasing aggregation with liquor de supersaturation and increased seed loading. The overall particle behaviours from the current investigation are validated by results obtained from previous gibbsite studies under very similar conditions. Although the gibbsite yield can be increased drastically in the presence of an anti solvent, the average particle size generated from this study is still too small to be commercially feasible due to the increase in initial supersaturation. Thus it is recommended that further particle size optimisation may be conducted inside a fluidised bed reactor where particles generally experience lower shear than inside a conventional agitated vessel.
Siebentritt, Matthieu. "Étude de l'entartrage par la gibbsite influence d'un substituant halogéné sur l'adsorption de l'alcool benzylique sur l'acier et la gibbsite." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/4886.
Full textPlagnieux, Virginie. "Influence des conditions d'agglomération sur la morphologie de la gibbsite et les propriétés d'usage de l'alumine." Vandoeuvre-les-Nancy, INPL, 2003. http://www.theses.fr/2003INPL088N.
Full textThe@improvement of the solidity of alumina which is produced for aluminium refinery and the reduction of fine particles generation which result of shocks during calcination and transport are essential points for the Bayer producers. The aim of this study is to link the gibbsite precipitation conditions to the morphology of the crystals and to verity their impact on alumina solidity. Analysis on industrial and lab-made products was done. We have focused our attention on the role of the agglomeration step. The experimental procedure was chosen to be as close as possible to the industrial process. Gibbsite morphology was quantified by using three visualization methods (optical microscopy with different immersion liquids, scanning electron microscopy on free powder and on polished section) and a setof different shape parameters. Five shape parameters quantify the two-dimensional shape of the crystals from the point of view of their roughness, elongation and concavity. Principal component analysis have enabled an information simplification for a better precision of the results and a better interpretation. The scanning electron microscope on free powder enables the tacet network visualization. Pseudo three dimensional parameters were calculated to describe the tacet network. On polished section, the crystal frames are weil defined and enable the sizing of the crystal sides related to the tacet sides. Alumina solidity was evaluated with a standardized fluidized bed and two indices. The attrition index quantifies the proportion of particles of size less than 45 1-1m which have been created du ring the test. The breakage index quantifies the evolution of the size distribution after the test
Lee, Mei-yin. "The mechanism of gibbsite crystal growth in Bayer liquor." Curtin University of Technology, School of Applied Chemistry, 1998. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10719.
Full textthat E growth occurs by spiral growth mechanism. The growth of the basal face was found to follow the spiral growth mechanism below a relative supersaturation of 0.815 and the birth and spread mechanism above this level. The activation energies and kinetic coefficients for the individual prismatic faces were also determined.Growth rate dispersion was observed in these microscopic studies, but the question of size dependency remains unanswered.The overall growth rates of gibbsite crystal, determined using rapid dynamic light scattering, was found to be an exponential function of supersaturation indicative of a birth and spread growth mechanism.
Fitzpatrick, Alexander John. "Adsorption of arsenate and phosphate on gibbsite from artificial seawater." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21552.
Full textThe waters of the Saguenay Fjord are also characterized by anomalously high particulate aluminum concentrations (i.e., [Al]tot/[Al] diss > 1), introduced as a result of the aluminum refining activity along the shores of its tributaries. Gibbsite (Al(OH)3), a by-product of this activity, is known to strongly adsorb phosphate and arsenate from low ionic strength aqueous solutions, and may act as a vector for these two elements to sediments of the Saguenay Fjord.
The small amount of arsenate and phosphate adsorbed onto gibbsite from seawater indicates that their adsorption to particulate aluminum in the water column cannot account for the elevated levels of arsenic and phosphate in the sediments of the Saguenay Fjord. (Abstract shortened by UMI.)
Fitzpatrick, Alexander John. "Adsorption of arsenate and phosphate on gibbsite from artificial seawater." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/MQ50768.pdf.
Full textLi, Tian Siong. "Modelling and kinetics estimation in gibbsite precipitation from caustic aluminate solutions." Curtin University of Technology, School of Applied Chemistry, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13672.
Full textKinetics estimation study from repeated batch gibbsite precipitation data showed that the uncertainty in the experimental data coupled with the error incurred from the kinetic parameter estimation procedure used, resulted in large uncertainties in the kinetics estimates. The influences of the experimental design and the kinetics estimation technique on the accuracy and precision of estimates of the nucleation, growth and agglomeration kinetics for the gibbsite precipitation system were investigated. It was found that the operating conditions have a greater impact on the uncertainties in the estimated kinetics than does the precipitator configuration. The kinetics estimates from the integral method, i.e. non-linear parameter optimisation method, describe the gibbsite precipitation data better than those obtained by the differential method. However, both kinetics estimation techniques incurred significant uncertainties in the kinetics estimates, particularly toward the end of the precipitation runs where the kinetics rates are slow. The uncertainties in the kinetics estimates are strongly correlated to the magnitude of kinetics values and are dependent on the change in total crystal numbers and total crystal volume. Batch gibbsite precipitation data from an inhomogeneously-mixed precipitator were compared to a well-mixed precipitation system operated under the same operating conditions, i.e. supersaturation, seed charge, seed type, mean shear rate and temperature.
It was found that the gibbsite agglomeration kinetic estimates were significantly different, and hence, the product CSD, but the gibbsite growth rates were similar. It was also found that a compartmental model approach cannot fully account for the differences in suspension hydrodynamics, and resulted in unsatisfactorily CSD predictions of the inhomogeneously-mixed precipitator. This is attributed to the coupled effects of local energy dissipation rate and solids phase mixing on agglomeration process.
St-Jean, Emilie. "Étude des phénomènes d'entartrage de la gibbsite sur les surfaces métalliques." Thèse, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/5162.
Full textBarajas, Carmen Leonor. "The effect of desferrioxamine B on Eu(III) interactions with gibbsite /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486546889383624.
Full textCao, Jie. "Synthesis of anisotropic plate-like nanostructures using gibbsite nanoplates as the template." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17755.
Full textIn the present thesis, efficient and simple modification approaches have been developed to coat gibbsite platelets with a controllable thickness of functional polymer shell, which preserves the plate-like morphology after the polymer coating. In the first part, a facile approach has been presented for the synthesis of anisotropic plate-like gibbsite-polydopamine (G-PDA) particles. Au NPs with tunable size have been formed on the G-PDA particle surface, which show efficient catalytic activity for the reduction of 4-nitrophenol and Rodamine B (RhB) in the presence of borohydride. Such nanocatalysts can be easily deposited on silicon substrate by spin coating due to the large contact area of the plate-like G-PDA particles and the strong adhesive behavior of the PDA layer. The substrate-deposited nanocatalyst can be easily recycled, which shows excellent reusability. Secondly, anisotropic hybrid core-shell microgels with well-defined structures have been synthesized using gibbsite nanoplate as core and crosslinked thermosensitive poly(N-isopropylacrylamide) as shell. The analysis by depolarized dynamic light scattering shows that the hybrid microgels have an anisotropic shape in the collapsed state, caused by the anisotropy of the plate-like core. In the third part, highly dispersible mesoporous nitrogen-doped hollow carbon nanoplates have been synthesized as a new carbon nanostructure via silica nanocasting technique using dopamine as carbon precursor and hexagonal-shaped gibbsite as template. Such hollow carbon nanoplates show excellent colloidal stability in aqueous media and can be directly applied as electrode materials in supercapacitors, which offer high capacitance and excellent electrochemical stability when using poly(ionic liquid) nanoparticles as binder.
Savary, Olivier. "Étude de la nucléation de la gibbsite par microscopie à force atomique." Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/4832.
Full textSilva, Wellington Barbosa da. "Caracterização da cobertura superficial em encosta na Bacia do Rio das Pombas, Guarapuava - PR: bases para entendimento da gênese erosiva em túneis." Universidade Estadual do Oeste do Parana, 2011. http://tede.unioeste.br:8080/tede/handle/tede/119.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
On the Guarapuava Plateau/Palmas, in a low slope hillside of superficial covering from basaltic origins, on the right bank of the Rio das Pombas, Paraná state, processes of tunnel erosion (pipes) were identified. These are subsuperficial erosion processes with typical features, such as subsidence of the tunnel roof and rebate structures, which tend to evolve to superficial features. The emerging of this erosive process depends on a set of factors, being the main one, the properties of the superficial covering, such as: texture, macroporosity, granulometric composition (chemical matter make-up), density, porosity e chemical elements that make up the matter, those concerning the hydrological conditions and the topography of the hillside. In order to recognize and characterize the superficial covering in the sector of low hillside, sieve analysis was used, as well as real and apparent density, total porosity verified; toposequences were made and X-ray scattering techniques performed. The results showed that the matter which covers the low hillside sector, where the tunnels are, have a sandy texture due to the properties of microagregation generated by clay mineral, gibbsite; leaving the matter with a high porosity level, thus favoring the flowing of water through subsurfaces. The generated flows tend to be exfiltrated to a ditch wall-like surface, which causes the removal of small particles of matter (seepage). With the opening of small gullies through subsurface, the flow tend to become concentrated (tunnel scour) and consequently enlarge the subsuperficial channels by the mechanical action of the water. In a sequence of factors that can be used for the analysis of the process generation, which causes: alteration in basalt rocks, microaggregation of the matter, macroporosity and increase of water flow through subsurface. Therefore, the hydrology conditions in the hillside contributed for erosion mechanisms to emerge in subsurface, development of erosion process, formation of subsuperficial erosion and, ultimately, superficial erosion process development. These both chemical and physical features found in such field of study, show that the superficial covering is a determining factor for the subsuperficial tunnel erosion to originate in the hillside.
No Planalto de Guarapuava/Palmas, em encosta de baixa declividade e cobertura superficial de origem basáltica, à margem direita do Rio das Pombas em Guarapuava (Paraná), foram identificados processos de erosão em túneis (pipes). Trata-se de processos subsuperficiais de erosão que apresentam feições típicas, tais como, subsidência do teto do túnel e estruturas de abatimento, que tendem a evoluir para feições superficiais. A instalação desse processo erosivo depende de um conjunto de fatores, destacando-se como condicionantes, as propriedades da cobertura superficial como: textura, macroporosidade, composição granulométrica, densidade, porosidade e constituintes químicos dos materiais, e aqueles relativos às condições hidrológicas e à topografia da encosta. Buscando-se reconhecer e caracterizar a cobertura superficial do setor de baixa encosta, foram realizadas análises granulométricas, de densidade aparente, real e porosidade total, construção de topossequências e análises químicas de difração de raios-X. Os resultados indicaram que o material que recobre o setor de baixa encosta, onde aparecem os túneis, apresenta textura arenosa devido às propriedades de microagregação gerada pelo argilomineral gibbsita, deixando o material com porosidade alta, favorecendo assim a circulação de água em subsuperficie. Os fluxos gerados tendem a ser exfiltrados para uma superfície de exposição, o que provoca a remoção de pequenas partículas de material (seepage). Com a abertura de pequenos canais em subsuperfície, os fluxos tendem a se concentrar (tunnel scour) e consequentemente ampliar os canais subsuperficiais pela ação mecânica da água. Numa sequência de fatores que possam ser postos para análise da geração do processo, têm-se: alteração da rocha basáltica, microagregação do material, macroporosidade e aumento da circulação de água em subsuperfície. Assume-se que as condições hidrológicas da encosta propiciaram a instalação de mecanismos de erosão em subsuperfície, evolução do processo erosivo, formação de feições erosivas subsuperficiais e, por fim, instalação de feições erosivas superficiais. Essas características físicas e químicas encontradas na área de estudo, demonstram que a cobertura superficial é determinante para a instalação da erosão subsuperficial em túneis na encosta.
Barbieri, Diogo Mazza [UNESP]. "Formas do relevo e variabilidade espacial de atributos químicos e mineralógicos de um argissolo cultivado com cana-de-açúcar." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/96884.
Full textConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A agricultura de precisão implica a análise da variabilidade espacial dos fatores de produção e a aplicação dos insumos de forma localizada e em doses precisas. O presente trabalho teve por objetivo analisar a influência do relevo na variabilidade espacial dos atributos químicos e mineralógicos para aplicação de insumos em taxa variável. Duas parcelas de um hectare foram delimitadas em área côncava e convexa. Foram retiradas 121 amostras em cada área. Os teores de P disponível apresentaram-se diferenciados nas duas áreas estudadas, sendo que os menores valores médios de P se encontram na área convexa na qual estão presentes os maiores teores de gibsita. A formação dos minerais da fração argila é condicionada pelas variações do relevo, sendo que a área convexa apresentou ambiente mais favorável à formação da gibsita do que a área côncava, demonstrando que o relevo pode ser utilizado para a definição de limites de área mais homogênea. A gibsita foi o fator determinante para a maior capacidade de adsorção máxima de P e a menor disponibilidade de fósforo na área convexa. O uso da técnica de geoestatística possibilitou a precisa descrição das propriedades do solo.
Precision agriculture implies on the analysis of the spatial variability of the production factors and the application of inputs in a localized way and on precise doses. The present work aimed to analyze the influence of the relief on the spatial variability of the chemical and mineralogical attributes for the application of inputs in variable rates. Two parcels of one hectare were bounded in concave and convex area. 121 samples were taken from each area. The levels of available P have shown to be different on the two studied areas, being the lowest mean values of P on the convex area, where the highest levels of gibbsite are present. The formation of the minerals from the clay fraction is conditioned by the relief variations, being that the convex area has presented a more favorable environment for the formation of gibbsite than the concave area, showing that relief may be used for the definition of limits in more homogenous areas. Gibbsite was the determinant factor for the higher capacity of P maximum adsorption and lower availability of phosphorous on the convex area. The use of the geostatistics technique has made possible the precise description of the soil properties.
Lectez, Sébastien. "Modélisation de l'interaction de l'ion uranyle à l'interface eau/gibbsite par la dynamique moléculaire quantique et classique." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00727757.
Full textCamargo, Livia Arantes [UNESP]. "Mineralogia da argila e atributos físicos de um argissolo em curvaturas de relevo." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/96979.
Full textFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Os atributos mineralógicos e físicos possuem dependência espacial e a distribuição espacial destes atributos possui relação com as formas do relevo. O objeto deste trabalho foi avaliar os atributos mineralógicos da fração argila e os atributos físicos de um argissolo em curvaturas do relevo, assim como avaliar a correlação entre esses atributos. Uma malha de dimensão 100 x 100 m foi delimitada em uma área caracterizada pela forma convexa e outra pela fôrma côncava. As malhas possuem espaçamento regular de 10 x 10 m e os pontos de cruzamento deste espaçamento determinaram os pontos de coleta das amostras, num total de 121 pontos amostrais georreferenciados em cada malha. Os atributos físicos foram avaliados nas profundidades 0,0- 0,2 e 0,2-0,4 m e os atributos mineralógicos na profundidade 0,0- 0,2 m. Os atributos físicos analisados foram diâmetro médio ponderado, diâmetro médio geométrico, agregados maiores que 2 mm, agregados entre 2 e 1 mm , agregados menores que 1 mm, microporos, macroporos, volume total de poros, densidade do solo, resistência do solo à penetração e teor de água no solo, já os atributos mineralógicos da fração argila foram largura a meia altura, diâmetro médio do cristal dos óxidos de ferro, da caulinita e gibbsita, substituição isomórfica e área de superfície específica da hematita e goethita. Os teores da goethita e hematita e razão goethita/(goethita+hematita) e razão caulinita/(caulinita+gibbsita) também foram calculados. Os dados foram submetidos às análises estatísticas e geoestatísticas para avaliação da variabilidade espacial e influência das curvaturas nestes atributos. Para avaliação da relação entre os atributos da mineralogia e físicos realizaram-se as análises de correlação simples e espacial. Os atributos físicos e mineralógicos apresentaram-se dependentes das curvaturas do relevo...
The mineralogicals and physical attributes have spatial dependence and the distribution of these attributes has relation with the forms of relief. The object of this study was to evaluate the attributes of clay mineralogy and the physical attributes of an argissol in curvatures of relief, as well as assess the correlation between these attributes. A grid size of 100 x 100 meters was defined in an area characterized by the convex shape and another in an area characterized by the concave shape. The grids have regular spacing of 10 x 10 m and the spacing of the points of intersection determine the points of collection of samples, a total of 121 georeferenced sample points in each grid. The physical attributes were evaluated in depth from 0.0 - 0.2 and 0.2 -0.4 m and the mineralogical attributes in depth 0,00-0,20 m. The physical attributes were analyzed: mean weight diameter, mean geometric diameter, aggregates larger than 2 mm, aggregates between 2 and 1 mm, aggregates smaller than 1 mm, microporosity, macroporosity, total porosity, bulk density, penetration resistance and water content in soil. The attributes of minerals were: width at half height, average diameter of crystals of iron oxides and kaolinite and gibbsite and isomorphic substitution and specific surface area of hematite and goethite. The contents of goethite and hematite and ratio goethite / (goethite + hematite) [Gt / (Gt + Hm)] and ratio kaolinite / (kaolinite + gibbsite) [Ct / (Ct + Gb)] were also calculated. Data were subjected to statistical and geostatistical analysis to evaluate the spatial variability and influence of these curvatures on these attributes. To assess the relation between mineralogy and physical attributes simple and spation correlation analysis where made. The physical and mineralogical attributes and depend on the curvature of the relief. There was also the influence of crystallinity of goethite and gibbsite in soil physical.
Tabassum, Rasheed, and tabassum rasheed@svt com au. "Scale growth study in a concentric reducer: Measurement of instantaneous velocity using Particle Image Velocimetry." Central Queensland University. School of Advance Technology and Processes, 2005. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20060720.095421.
Full textIngram-Jones, Victoria Jane. "A physicochemical investigation of transition aluminas." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307319.
Full textPhambu, Nsoki. "Préparation d'hydroxydes d'aluminium : caractérisation structurale morphologique et superficielle : application à l'étude d'une couche de passivation d'aluminium." Nancy 1, 1996. http://www.theses.fr/1996NAN10325.
Full textRanguis-Barale, Isabelle. "Étude de la fragmentation ultrafine : application au broyage de la gibbsite par broyeur à jets d'air." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL062N.
Full textVachon, Annick. "Étude de l'inhibition de l'entartrage de l'acier doux 1018 par la gibbsite dans le procédé Bayer." Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/4810.
Full textRosenqvist, Jörgen. "Surface chemistry of Al and Si (hydr)oxides, with emphasis on nano-sized gibbsite (α-Al(OH)3)." Doctoral thesis, Umeå universitet, Kemi, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-6.
Full textCao, Jie [Verfasser], Matthias [Gutachter] Ballauff, and Nicola [Gutachter] Pinna. "Synthesis of anisotropic plate-like nanostructures using gibbsite nanoplates as the template / Jie Cao ; Gutachter: Matthias Ballauff, Nicola Pinna." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://d-nb.info/1131141172/34.
Full textGarand, Alain. "The influence of ionic strength and fluoride ion concentration on the adsorption properties of gibbsite : phosphate and arsenate adsorption." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78363.
Full textIn order to simulate the behavior of the adsorbent/adsorbate relationship during estuarine mixing, the adsorption capacity of gibbsite for arsenate and phosphate was measured in pure water; 0.67 M NaCl; 10 mM CaCl2; 10 mM CaCl2 + 0.64 M NaCl and in seawater in the absence and presence of the fluoride ion.
Bouchard, Nicolas-Alexandre. "Étude des propriétés d'absorption sur la surface de la gibbsite de composés organiques modifiés électrochimiquement et leurs effets sur la précipitation." [S.l. : s.n.], 2007.
Find full textJamet, Rémi. "Pedogenese sur roches basaltiques en polynesie francaise : d'oxydisols a des podzols a gibbsite et anatase, genese des concentrations superficielles de titane." Orléans, 1997. http://www.theses.fr/1997ORLE2013.
Full textBouchard, Nicolas-Alexandre. "Étude des propriétés d'absorption sur la surface de la gibbsite de composés organiques modifiés électrochimiquement et leurs effets sur la précipitation." Thèse, Université de Sherbrooke, 2007. http://savoirs.usherbrooke.ca/handle/11143/5081.
Full textBennett, Ian John. "Development and evaluation of alumina calcination." Thesis, University of Bath, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340929.
Full textBélaroui, Karima. "Compréhension des mécanismes de fragmentation par analyse granulométrique et morphologique." Vandoeuvre-les-Nancy, INPL, 1999. http://docnum.univ-lorraine.fr/public/INPL_T_1999_BELAROUI_K.pdf.
Full textComminution is an important process in powder technology, in which progress can still be made, to improve the operation of existing equipments or to design new systems. To understand better the phenomena taking place in the grinding chambers, the classical approach based on the examination of size distributions has been combined with the distributions of the shape of the fragments, observed by scanning electron microscopy and characterised by image analysis. The particle morphology has been assessed through the use of a set of seven parameters, six of them describing the 2D shape and one the pseudo 3D shape. In complement statistical tools (tests, principal component analysis) have been used. Comminution experiments have been run with different materials exhibiting either welldefined initial morphology (gibbsites obtained by crystallisation) or not (natural rocks) in a stirred bead-mill with different suspension concentrations, and beads diameters and filling rates. After a preliminary study of the particles before grinding, the analysis of the size reduction phenomena from the size distributions only has shawn its limits. The method finally proposed is based on a joint analysis of the shape and size parameters. If a better understanding of the phenomena can help to control the product quality, a possible pollution by fines produced by wear of the grinding bodies should be taken into account. A method based on the analysis of their surface by scanning electron microscopy is proposed to monitor this wear
Massola, Camila Peres. "Flotação reversa da bauxita de Miraí - MG." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-25092008-094000/.
Full textThis research presents the results achieved by the author in recovering gibbsite from industrial bauxite tailings. The tailings samples were provided by Companhia Brasileira de Alumínio CBA, from it´s Itamarati de Minas, MG plant. The CBA´s Itamarati de Minas plant has a complete circuit of scrubbing, desliming, and heavy minerals separation in spiral concentrators, complemented by high intensity magnetic separation, but it still loses the values contained in the fine fraction of the beneficiated ore, which currently consists of a tailing. Reverse flotation of the insoluble silica present in this tailings stream, followed by magnetic separation of the depressed product, allows to recover gibbsite, and produces silica sand, which can be used in civil construction work and road maintenance. The magnetic concentrate can be used as a charge additive to Portland cement production. Thus, the beneficiation of this fraction is important both economically and for mineral resources conservation. Through experimentation on bench and at pilot plant scale tests, this work explores the feasibility of such a process to the bauxites from Miraí, southeastern Minas Gerais state. After magnetic separation, the concentrate reached available alumina grades of 54% at pilot plant, with 28.8% mass recovery and 81.2% metallurgical recovery, with a Al2O3/SiO2 ratio of 12.6. This shows viability for industrial scale application of the process.
Demoisson, Frédéric. "Réactivité aux échelles micronique et submicronique de particules colloïdales : oxydation d'un sulfure de fer (pyrite) par du chrome (VI) et sorption sur un hydroxyde d'aluminium (gibbsite) d'espèces organiques." Nancy 1, 2006. http://docnum.univ-lorraine.fr/public/SCD_T_2006_0004_DEMOISSON.pdf.
Full textTwo systems characterised by oxydoreduction and sorption of surface reactions are studied: the pyrite oxidation (FeS2) by chromium (VI) and the sorption of dinitro-2,4 benzoic species on gibbsite (γ-Al(OH)3). The aim of the first system is to study the pyrite oxidation processes of the pyrite by using chromium (VI) like a metal probe. The solution analysis by UV-visible spectroscopy and the solid phase characterisation by confocal Raman spectrometry, XPS, EXAFS and XANES allow to suggest a mechanism model of oxidation/dissolution. The objective of the second study is to display a specific chemical reactivity between two crystalline face types of the gibbsite by using an organic probe with the help of sub-wavelength spectroscopy (SNOM). Correlations between crystalline faces and near field spectra show difference reactivity between mono and bi coordinated OH groups from the mineral phase. A model of sorption is presented
Camargo, Livia Arantes. "Mineralogia da argila e atributos físicos de um argissolo em curvaturas de relevo /." Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/96979.
Full textAbstract: The mineralogicals and physical attributes have spatial dependence and the distribution of these attributes has relation with the forms of relief. The object of this study was to evaluate the attributes of clay mineralogy and the physical attributes of an argissol in curvatures of relief, as well as assess the correlation between these attributes. A grid size of 100 x 100 meters was defined in an area characterized by the convex shape and another in an area characterized by the concave shape. The grids have regular spacing of 10 x 10 m and the spacing of the points of intersection determine the points of collection of samples, a total of 121 georeferenced sample points in each grid. The physical attributes were evaluated in depth from 0.0 - 0.2 and 0.2 -0.4 m and the mineralogical attributes in depth 0,00-0,20 m. The physical attributes were analyzed: mean weight diameter, mean geometric diameter, aggregates larger than 2 mm, aggregates between 2 and 1 mm, aggregates smaller than 1 mm, microporosity, macroporosity, total porosity, bulk density, penetration resistance and water content in soil. The attributes of minerals were: width at half height, average diameter of crystals of iron oxides and kaolinite and gibbsite and isomorphic substitution and specific surface area of hematite and goethite. The contents of goethite and hematite and ratio goethite / (goethite + hematite) [Gt / (Gt + Hm)] and ratio kaolinite / (kaolinite + gibbsite) [Ct / (Ct + Gb)] were also calculated. Data were subjected to statistical and geostatistical analysis to evaluate the spatial variability and influence of these curvatures on these attributes. To assess the relation between mineralogy and physical attributes simple and spation correlation analysis where made. The physical and mineralogical attributes and depend on the curvature of the relief. There was also the influence of crystallinity of goethite and gibbsite in soil physical.
Orientador: José Marques Júnior
Coorientador: Gener Tadeu Pereira
Banca: Marcílio Vieira Martins Filho
Banca: Zigomar Menezes de Souza
Mestre
Gückel, Katharina [Verfasser], Gert [Akademischer Betreuer] Bernhard, Karsten [Akademischer Betreuer] Gloe, and T. David [Akademischer Betreuer] Waite. "Structural analysis of ternary actinyl(V/VI) sorption complexes on gibbsite : – A combined quantum chemical and spectroscopic approach / Katharina Gückel. Gutachter: Karsten Gloe ; T. David Waite. Betreuer: Gert Bernhard." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://d-nb.info/1068154276/34.
Full textBarbieri, Diogo Mazza. "Formas do relevo e variabilidade espacial de atributos químicos e mineralógicos de um argissolo cultivado com cana-de-açúcar /." Jaboticabal : [s.n.], 2007. http://hdl.handle.net/11449/96884.
Full textAbstract: Precision agriculture implies on the analysis of the spatial variability of the production factors and the application of inputs in a localized way and on precise doses. The present work aimed to analyze the influence of the relief on the spatial variability of the chemical and mineralogical attributes for the application of inputs in variable rates. Two parcels of one hectare were bounded in concave and convex area. 121 samples were taken from each area. The levels of available P have shown to be different on the two studied areas, being the lowest mean values of P on the convex area, where the highest levels of gibbsite are present. The formation of the minerals from the clay fraction is conditioned by the relief variations, being that the convex area has presented a more favorable environment for the formation of gibbsite than the concave area, showing that relief may be used for the definition of limits in more homogenous areas. Gibbsite was the determinant factor for the higher capacity of P maximum adsorption and lower availability of phosphorous on the convex area. The use of the geostatistics technique has made possible the precise description of the soil properties.
Orientador: José Marques Júnior
Coorientador: Gener Tadeu Pereira
Banca: Luis Reynaldo Ferracciú Alleoni
Banca: Marcilio Vieira Martins Filho
Mestre
Assos, Charalambos. "Organic ligand complexation reactions on aluminium-bearing mineral surfaces studied via in-situ multiple internal reflection infrared spectroscopy, adsorption experiments, and surface complexation modelling." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/organic-ligand-complexation-reactions-on-aluminiumbearing-mineral-surfaces-studied-via-insitu-multiple-internal-reflection-infrared-spectroscopy-adsorption-experiments-and-surface-complexation-modelling(43f53df4-8d74-4237-a67e-9b86f2dee9ac).html.
Full textGudbrandsson, Snorri. "Experimental weathering rates of aluminium-silicates." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2225/.
Full textThe chemical weathering of primary rocks and minerals in natural systems has a major impact on soil development and its composition. Chemical weathering is driven to a large extent by mineral dissolution. Through mineral dissolution, elements are released into groundwater and can readily react to precipitate secondary minerals such as clays, zeolites, and carbonates. Carbonates form from divalent cations (e. G. Ca, Fe and Mg) and CO2, and kaolin clay and gibbsite formation is attributed to the weathering of aluminium- rich minerals, most notably the feldspars. The CarbFix Project in Hellisheiði SW-Iceland aims to use natural weathering processes to form carbonate minerals by the re-injection of CO2 from a geothermal power plant back into surrounding basaltic rocks. This process is driven by the dissolution of basaltic rocks, rich in divalent cations, which can combine with injected CO2 to form and precipitate carbonates. This thesis focuses on the dissolution behaviour of Stapafell crystalline basalt, which consists of three major phases (plagioclase, pyroxene, and olivine) and is rich in divalent cations. Steady-state element release rates from crystalline basalt at far-from-equilibrium conditions were measured at pH from 2 to 11 and temperatures from 5° to 75° C in mixed-flow reactors. Steady-state Si and Ca release rates exhibit a U-shaped variation with pH, where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Silicon release rates from crystalline basalt are comparable to Si release rates from basaltic glass of the same chemical composition at low pH and temperatures =25°C but slower at alkaline pH and temperatures =50°C. In contrast, Mg and Fe release rates decrease continuously with increasing pH at all temperatures. This behaviour is interpreted to stem from the contrasting dissolution behaviours of the three major minerals comprising the basalt: plagioclase, pyroxene, and olivine. Element release rates estimated from the sum of the volume fraction normalized dissolution rates of plagioclase, pyroxene, and olivine are within one order of magnitude of those measured in this study. In addition, these experimental results show that during injection of CO2-charged waters with pH close to 3. 6, crystalline basalt preferentially releases Mg and Fe relative to Ca to the fluid phase. The injection of acidic CO2-charged fluids into crystalline basaltic rocks may therefore favour the formation of Mg and Fe carbonates rather than calcite at acidic to neutral conditions. Plagioclase is the most abundant phase in crystalline basalts and thus influences strongly its reactivity. Plagioclase dissolution rates based on Si release show a common U-shaped behaviour as a function of pH where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Constant pH plagioclase dissolution rates increase with increasing anorthite content at acid conditions, in agreement with literature findings. Interpretation and data fitting suggests that plagioclase dissolution rates are consistent with their control by the detachment of Si-rich activated complexes formed by the removal of Al from the mineral framework. Most notably, compared with previous assumptions, plagioclase dissolution rates are independent of plagioclase composition at alkaline conditions, e. G. Anorthite-rich plagioclase dissolution rates increase with increasing pH at alkaline conditions. At such conditions rapid plagioclase dissolution rates likely dominate divalent metal release from crystalline basalts to the fluids phase due to its high Ca content. Gibbsite is commonly the first mineral formed during low temperature dissolution of plagioclase. Gibbsite is an aluminium-hydroxide that is found in various soils as well as the dominant phase in many bauxite ores. Gibbsite precipitation rates were measured in closed system reactors at alkaline condition, both at 25 °C and 80 °C as a function of fluid saturation state. Analyses of the solids demonstrate that gibbsite precipitation occurred in all experiments. The comparison of gibbsite precipitation to the dissolution rates of plagioclase at pH 11 shows that the rates are close to equal. The precipitation rates of gibbsite, however, decrease faster with decreasing pH than plagioclase dissolution rates. As such it seem likely that plagioclase dissolution is faster than gibbsite precipitation at near to neutral pH, and the relatively slow rate of gibbsite precipitation influences plagioclase weathering in many Earth surface systems. Kaolinite is commonly the second secondary mineral formed during low temperature dissolution of plagioclase. Kaolinite precipitation rates were measured in mixed flow reactors as a function of fluid saturation state at pH=4 and 25 °C. In total eight long-term precipitation experiments were performed in fluids mildly supersaturated with respect to kaolinite, together with a known quantity of cleaned low defect Georgia Kaolinite as seeds. Measured kaolinite precipitation rates are relatively slow compared with plagioclase dissolution rates. This observation suggests that kaolinite formation during weathering is limited by its precipitation rates rather than by the availability of aqueous species sourced from plagioclase dissolution. Taken together the results of this study provide some of the fundamental scientific basic for predicting the rates and consequences of crystalline basalt and plagioclase dissolution at both the Earth's surface and during the near surface injection of CO2 as part of carbon storage efforts. Results indicate that although gibbsite precipitation rates are relatively rapid, the relatively slow precipitation rates of kaolinite may be the process controlling the formation of this mineral at the Earth's surface. This observation highlights the need to further quantify this secondary mineral precipitation rates at conditions typical at the Earth's surface. Moreover, as the composition of divalent metals released from crystalline basalts varies significantly with pH, CO2 carbonation in basalt should yield a systematic variation in the identity of carbonate and zeolite minerals precipitated with distance from the injection site. This latter conclusion can be tested directly as part of the currently on-going CarbFix project in Hellisheiði, Iceland
Schwabe, Jeremia [Verfasser], and Rolf [Akademischer Betreuer] Mülhaupt. "Gibbsit- und Aluminiumoxid-Einkristallnanoplättchen für PE-Nanokomposite, Mehrzentrenträgerkatalysatoren und selbstverstärkendes Polyethylen." Freiburg : Universität, 2015. http://d-nb.info/1119805759/34.
Full textMolis, Elisabeth. "Dissolution en suspension et en position d'intercalation des formes hydrolysées de l'aluminium en interaction avec des ligands organiques." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL123N.
Full textKirschvink, Felix [Verfasser], and Rolf [Akademischer Betreuer] Mülhaupt. "Semikristalline Blockcopolymere, Graphen- und Gibbsit-Nanokomposite durch Kettenübertragung bei der ringöffnenden Metathesepolymerisation von cis-Cycloocten." Freiburg : Universität, 2016. http://d-nb.info/1125905557/34.
Full textSoares, Liliane Catone. "Estudo da retenção de cromo em alumina, gibbsita e aluminossilicatos e avaliação dos processos de lixiviação." Universidade Federal de Minas Gerais, 2010. http://hdl.handle.net/1843/SFSA-88EQGT.
Full textEncontram-se na literatura diferentes processos envolvendo tratamento de soluções contendo metais pesados na sua forma iônica. O método mais empregado para a remoção de metais pesados de efluentes baseia-se na precipitação dos cátions metálicos, em solução, pela adição de agentes precipitantes. Estes agentes podem ser soluções de hidróxidos ou de sulfetos, pois estas geram precipitados de baixa solubilidade. No entanto, apesar de muito eficiente, a precipitação é um método de tratamento sujeito a críticas porque gera um resíduo sólido e, portanto, não soluciona totalmente o problema. Assim, além dos métodos baseados em precipitação, existem os baseados em adsorção e troca iônica. Diversos estudos de retenção de metais pesados por adsorventes e trocadores iônicos têm sido relatados na literatura. Dentre eles, destacam-se os aluminossilicatos e, especificamente, as zeólitas. Neste trabalho, relatamos o estudo da retenção do íon cromo por alumina, gibbsita, uma peneira molecular comercial e caulinita, um aluminossilicato natural, em diferentes condições de concentração de cromo em solução, temperatura e tempo de contato entre as soluções e as fases estacionárias, paralelamente com estudos de lixiviação do íon cromo retido nesses materiais. Embora sejam necessários experimentos complementares para elucidar a natureza intrínseca do processo de retenção, verificou-se que a peneira molecular e a gibbsita são as fases mais eficientes para a retenção do íon cromo, ambas com capacidade de retenção quase total e alta resistência a processos de lixiviação.
Le, Ny Arnaud. "Mesures de gibbs sur une reseau et non-gibbsiannite : restauration du formalisme gibbsien." Rennes 1, 2000. http://www.theses.fr/2000REN10062.
Full textPINHEIRO, Darllan do Rosário. "Adsorção de CU2+ em alumina de transição obtida a partir da mistura de gibbsita e hidróxido de alumínio gel." Universidade Federal do Pará, 2015. http://repositorio.ufpa.br/jspui/handle/2011/7709.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A alumina é um dos óxidos mais importantes na indústria cerâmica, sendo utilizado principalmente na forma de alumina calcinada ou fundida sendo aplicada, dentre outras formas, como material adsorvente. Neste trabalho desenvolveu-se um método de produção de alumina de transição a partir da mistura de gibbsita, proveniente do processo Bayer, e hidróxido de alumínio gel, proveniente de reação de sulfato de alumínio e hidróxido de amônio visando a aplicação como material adsorvente para remoção de Cu 2+ em solução aquosa. Foram investigadas as condições de adsorção incluindo tempo de contato e pH. Os ensaios foram realizados a 30 oC e 50 ºC, nos quais 1 g de alumina produzida foi submetida a contato com 100 ml de uma solução aquosa contendo Cu2+. As concentrações das soluções aquosas empregadas foram de 100, 200, 400, 800, 1600 e 2000 ppm de solução de sulfato de cobre. A caracterização das soluções de sulfato de cobre foi realizada em espectrofotometria UV e a caracterização do material produzido foi realizada através de DRX, EDX e área superficial BET. Avaliou-se o tempo de contato para o alcance do equilíbrio de adsorção sendo este tempo otimizado em 15 min. O efeito do pH sobre a adsorção mostrou que aumentando a temperatura de adsorção há um aumento do valor de pH em relação ao pH da solução inicial de sulfato de cobre. As isotermas de Langmuir e Freundlich apresentaram resultados satisfatórios para adsorção, sendo a isoterma de Langmuir a que melhor se ajustou aos dados de adsorção. Através das isotermas de equilíbrio verificou-se que o material produzido tem boa capacidade de adsorção para o íon Cu2+.
Alumina is one of the most important oxides in the ceramic industry, being used mainly in the form of calcined alumina or fused applied, among other ways, as adsorbent material. In this work is a transition alumina production method from a mixture of gibbsite, from the Bayer process, gel and aluminum hydroxide, from the reaction of aluminum sulfate and ammonium hydroxide targeting the application as an adsorbent material for removing Cu2 + in aqueous solution. Adsorption conditions including contact time and pH were investigated. Assays were carried out at 30 ° C and 50 ° C, in which 1 g of alumina produced was subjected to contact with 100 ml of an aqueous solution containing Cu2 +. The concentrations of the aqueous solutions employed were 100, 200, 400, 800, 1600 and 2000 ppm copper sulphate solution. The characterization of copper sulfate solutions was performed in UV spectrophotometry and characterization of the material produced was carried out by XRD, EDX and BET surface area. Evaluated the contact time to achieve the adsorption equilibrium which is optimized time 15 min. The effect of pH on the adsorption shows that the adsorption temperature increases there is an increased pH compared with the pH of the initial solution of copper sulfate. The isotherms of Langmuir and Freundlich had satisfactory results for adsorption, and the Langmuir isotherm that better fits the adsorption data. Through the equilibrium isotherms it was found that the material produced has adsorption capacity for Cu2 + ion.
Gudbrandsson, Snorri. "Vitesses d'altération expérimentales des silicates d'aluminium." Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00933440.
Full textVivaldi, Daniella Dias. "Avaliação dos processamentos de correção atmosférica e de crosstalk em dados ASTER para identificação de relação mineralógica Caulinita/(Caulinita+Gibbsita) em solos tropicais." reponame:Repositório Institucional da UnB, 2013. http://repositorio.unb.br/handle/10482/14061.
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O objetivo do presente estudo foi verificar a influência da correção atmosférica e de crosstalk a espacialização da relação Caulinita/(Caulinita+Gibbsita) em solos dos municípios de Niquelândia e de São João d’Aliança – GO, por meio da aplicação do índice espectral RCGb scale, desenvolvido por Baptista (2001), em imagens ASTER SWIR L1A e L1B, e em produtos sob demanda AST_07 e AST_07XT. Nesse estudo foram utilizados os módulos FLAASH e QUAC, para a correção atmosférica e o software CRSTX 30, para a correção do efeito crosstalk. A câmara SWIR do ASTER é afetada por um problema de “vazamento” de sinal, o crosstalk que ocorre nos detectores da banda 4 sobre os detectores das bandas vizinhas, ou seja, nas bandas 5 e 9, afetando o sinal detectado. Com isso, os espectros dos dados ASTER-SWIR apresentam um deslocamento das feições de absorção da caulinita, e essa, juntamente com a gibbsita são utilizadas para a determinação do grau de intemperismo os solos tropicais. De acordo com os resultados das imagens conclui-se que, para o município São João d’Aliança, para a investigação da relação mineralógica em solos, o produto sob demanda ASTER AST-07 – imagem de reflectância sem correção crosstalk e com correção atmosférica, a imagem L1B convertida para reflectância, com correção crosstalk, por meio do software CRSTK30 e com correção atmosférica, por meio da aplicação do algoritmo QUAC; a imagem de radiância L1B (radiância no nível do sensor) sem correção crosstalk e sem correção atmosférica; a imagem L1B convertida para reflectância, por meio do módulo Flat Field, sem correção crosstalk e sem correção atmosférica; a imagem L1B convertida para reflectância, por meio do módulo Flat Field, com correção crosstalk e sem correção atmosférica e produto sob demanda ASTER AST- 07XT – imagem de reflectância com correção crosstalk e com correção atmosférica são as mais adequadas. No caso de Niquelândia, a imagem de radiância L1B (radiância no nível do sensor) sem correção crosstalk e sem correção atmosférica; a imagem L1B convertida para reflectância, por meio do módulo Flat Field, sem correção crosstalk e sem correção atmosférica; a imagem L1B convertida para reflectância, por meio do módulo Flat Field, com correção crosstalk e sem correção atmosférica; a imagem L1B convertida para reflectância, com correção crosstalk, por meio do software CRSTK30 e com correção atmosférica por meio da aplicação do algoritmo FLAASH e a imagem de radiância L1A convertida para reflectância, sem correção crosstalk e com correção atmosférica por meio da aplicação do algoritmo QUAC, são as mais adequadas para a investigação da espacialização da relação Caulinita/(Caulinita+Gibbsita). Desse modo, os valores obtidos por meio da aplicação do RCGb scale , índice proporcional ao valor Ki dos solos, apresentaram proximidade aos valores referentes às amostras de campo na maioria dos processamento realizados tanto para Niquelândia como para São João d’Aliança, confirmando, assim a potencialidade desse índice sobre os dados ASTER. ______________________________________________________________________________ ABSTRACT
The aim of this study was to investigate the influence of atmospheric correction and crosstalk of the spatial relationship of kaolinite/(kaolinite + gibbsite) in soils of São João d’Aliança.- GO, by applying the spectral index RCGb scale, developed by Baptista (2001), ASTER images in L1A and L1B-SWIR, and AST_07 AST_07XT on-demand products. The area of study is located in São João d’Aliança-GO, that is cut by Serra Geral do Parana and has part of its area in Vale do Parana, which has flattened topography, with slopes less than 3% . For this paper FLAASH and QUAC modules were used for the atmospheric correction software, and CRSTX 30, to correct the crosstalk effect. The SWIR ASTER camera is affected by a problem of "leakage" signal, the crosstalk that occurs in the band 4 detectors on auto neighboring bands, ie, bands 5 and 9, affecting the signal detected. Considering that, the ASTER-SWIR spectra shows a shift of absorption features of kaolinite, and this, together with gibbsite are used for determining the degree of weathering of tropical soils. According to the results of the images we conclude that, for the county of São João d’Aliança, for mineralogical investigation of the relationship, the ASTER AST-07 product demand - image reflectance without crosstalk correction and with atmospheric correction, the L1B converted to reflectance image with crosstalk correction, through CRSTK30 software and atmospheric correction by applying the QUAC's algorithm, L1B radiance image (radiance at sensor level) without crosstalk correction and without atmospheric correction, the L1B image converted to reflectance through the Flat Field module, without crosstalk correction and atmospheric correction, the L1B image converted to reflectance through the Flat Field module, with crosstalk correction and without atmospheric correction ASTER AST-07XT product demand - reflectance image with rosstalk correction and atmospheric correction are the most appropriate. Where Niquelândia, the image of L1B radiance (radiance at sensor level) without crosstalk correction and without atmospheric correction, the image L1B converted to reflectance through the Flat Field module without crosstalk correction and without atmospheric correction, the image L1B converted to reflectance through the module Flat Field correction crosstalk with and without atmospheric correction, the image L1B converted to reflectance, with crosstalk correction, through software CRSTK30 and atmospheric correction by applying the algorithm and the image of radiance FLAASH L1A converted to reflectance, no crosstalk correction and atmospheric correction by applying the algorithm QUAC, are best suited for the investigation of the spatial relationship of kaolinite/(kaolinite+gibbsite). Thereby, the values obtained by applying the RCGb scale , Ki proportional index to the land value, presents proximity to the field samples figures in most processing done to Niquelândia and São João d’Aliança., thus confirming the potential of this index on ASTER data.
Fernandes, Kathleen Lourenço [UNESP]. "Estimativa da caulinita e gibbsita por técnicas de difração de raios x e espectroscopia de reflectância difusa dos solos do Planalto Ocidental Paulista." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/149918.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Planalto Ocidental Paulista (POP) é uma das principais áreas de cultivo de citros do país, representando cerca de 80% da produção nacional, tendo ainda grande participação na produção de açúcar e álcool. A caracterização e quantificação mineralógica dos solos desta região torna-se importante para melhor entendimento dos processos pedogênicos do solo, e uso de melhores práticas de manejo. Por meio de ferramentas como a geoestatística é possível entender a relação entre a mineralogia do solo e as formas da paisagem, indicando a variabilidade espacial dos dados e a dependência entre os atributos pedogênicos e os geomórficos da região. Assim, o presente trabalho teve como objetivos: a) caracterizar os teores e a cristalinidade da caulinita (Ct) e gibbsita (Gb), e suas relações com os diferentes compartimentos geológicos e geomorfológicos do POP; b) e avaliar o potencial de diferentes metodologias aplicadas às curvas espectrais, dada pela técnica de espectroscopia de reflectância difusa (ERD), para estimativa da razão entre Ct e Gb, e caracterizar a variabilidade espacial da razão para o POP. Foram coletadas 600 amostras de solo georreferenciadas, próximas às principais rodovias do estado de São Paulo. Para quantificação dos teores e cristalinidade da Ct e Gb foi utilizada a técnica de difratometria de raios X (DRX) e a metodologia de Rietveld. A quantificação não convencional pela técnica de ERD, foi feita por três metodologias aplicadas às curvas espectrais: contínuo removível, relação direta do vale e regressão mínima por quadrados parciais. Os dados foram submetidos a análises de estatística descritiva, análise de regressão (para comparativo entre as técnicas) e análises geoestatísticas, pela krigagem simples. Os compartimentos geológicos e geomorfológicos influenciam na distribuição dos teores de Ct e Gb, e na formação cristalográfica destes. Ambientes de geologia Arenítica apresentam maiores teores de Ct, menos cristalinas, e ambientes de Basalto maiores teores de Gb de maior cristalinidade. A ERD mostrou-se como uma técnica eficiente para a estimativa não convencional dos minerais, tendo a metodologia do contínuo removível apresentado os melhores parâmetros estatísticos, entre a comparação de valores dados pela DRX e pela ERD. A variabilidade espacial da razão entre Ct e Gb, apresentou padrões semelhantes entre os mapas de dados da DRX e ERD, para ambas as metodologias.
The Ouest Paulista Plateau (POP) is one of the main areas of citrus cultivation in the country, accounting for about 80% of the national production, with a large share of sugar and alcohol production. The characterization and mineralogical quantification of the soils of this region becomes important for a better understanding of the soil pedogenic processes, and the use of better management practices. Through tools such as geostatistics, it is possible to understand the relationship between soil mineralogy and landscape forms, indicating the spatial variability of the data and the dependence between the pedogenic and geomorphic attributes of the region. Thus, the present work had as objectives: a) to characterize the contents and crystallinity of kaolinite (Kt) and gibbsite (Gb), and its relations with the different geological and geomorphological compartments of POP; B) and to evaluate the potential of different methodologies applied to the spectral curves, given by the diffuse reflectance spectroscopy (DRS) technique, to estimate the ratio between Ct and Gb, and to characterize the spatial variability of the ratio for the POP. A total of 600 georeferenced soil samples were collected near the main highways in the state of São Paulo. The X-ray diffraction (XRD) technique and the Rietveld methodology were used to quantify the Ct and Gb contents and crystallinity. The unconventional quantification by the DRS technique was done by three methodologies applied to the spectral curves: removable continuous, direct ratio of the valley and minimum regression by partial squares. Data were submitted to descriptive statistics analysis, regression analysis (for comparison between the techniques) and geostatistical analysis, by simple kriging. The geological and geomorphological compartments influence the distribution of Kt and Gb contents and their crystallographic formation. Environments of sandstone geology have higher levels of Ct, less crystalline, and environments of basalt greater Gb levels of greater crystallinity. DRS proved to be an efficient technique for the unconventional estimation of minerals, and the methodology of the removable continuum presented the best statistical parameters between the comparison of values given by the XRD and the DRS. The spatial variability of the ratio between Kt and Gb presented similar patterns between the XRD and DRS data maps for both methodologies.
FAPESP: 2015/20692-0
Fernandes, Kathleen Lourenço. "Estimativa da caulinita e gibbsita por técnicas de difração de raios x e espectroscopia de reflectância difusa dos solos do Planalto Ocidental Paulista /." Jaboticabal, 2017. http://hdl.handle.net/11449/149918.
Full textCoorientador: Angélica Santos Rabelo de Souza Bahia
Banca: Adriana Aparecida Ribon
Banca: Newton La Scala Junior
Resumo: Planalto Ocidental Paulista (POP) é uma das principais áreas de cultivo de citros do país, representando cerca de 80% da produção nacional, tendo ainda grande participação na produção de açúcar e álcool. A caracterização e quantificação mineralógica dos solos desta região torna-se importante para melhor entendimento dos processos pedogênicos do solo, e uso de melhores práticas de manejo. Por meio de ferramentas como a geoestatística é possível entender a relação entre a mineralogia do solo e as formas da paisagem, indicando a variabilidade espacial dos dados e a dependência entre os atributos pedogênicos e os geomórficos da região. Assim, o presente trabalho teve como objetivos: a) caracterizar os teores e a cristalinidade da caulinita (Ct) e gibbsita (Gb), e suas relações com os diferentes compartimentos geológicos e geomorfológicos do POP; b) e avaliar o potencial de diferentes metodologias aplicadas às curvas espectrais, dada pela técnica de espectroscopia de reflectância difusa (ERD), para estimativa da razão entre Ct e Gb, e caracterizar a variabilidade espacial da razão para o POP. Foram coletadas 600 amostras de solo georreferenciadas, próximas às principais rodovias do estado de São Paulo. Para quantificação dos teores e cristalinidade da Ct e Gb foi utilizada a técnica de difratometria de raios X (DRX) e a metodologia de Rietveld. A quantificação não convencional pela técnica de ERD, foi feita por três metodologias aplicadas às curvas espectrais: contínuo removível, ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Ouest Paulista Plateau (POP) is one of the main areas of citrus cultivation in the country, accounting for about 80% of the national production, with a large share of sugar and alcohol production. The characterization and mineralogical quantification of the soils of this region becomes important for a better understanding of the soil pedogenic processes, and the use of better management practices. Through tools such as geostatistics, it is possible to understand the relationship between soil mineralogy and landscape forms, indicating the spatial variability of the data and the dependence between the pedogenic and geomorphic attributes of the region. Thus, the present work had as objectives: a) to characterize the contents and crystallinity of kaolinite (Kt) and gibbsite (Gb), and its relations with the different geological and geomorphological compartments of POP; B) and to evaluate the potential of different methodologies applied to the spectral curves, given by the diffuse reflectance spectroscopy (DRS) technique, to estimate the ratio between Ct and Gb, and to characterize the spatial variability of the ratio for the POP. A total of 600 georeferenced soil samples were collected near the main highways in the state of São Paulo. The X-ray diffraction (XRD) technique and the Rietveld methodology were used to quantify the Ct and Gb contents and crystallinity. The unconventional quantification by the DRS technique was done by three methodologies applied to the spectral curves: removable continuous, direct ratio of the valley and minimum regression by partial squares. Data were submitted to descriptive statistics analysis, regression analysis (for comparison between the techniques) and geostatistical analysis, by simple kriging. The geological and geomorphological compartments influence the distribution of Kt and Gb con ... (Complete abstract click electronic access below)
Mestre
Wang, Pai-Cheng, and 王百晟. "Deintercalation mechanism of Li-intercalated gibbsite." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/57191187281098478308.
Full text中興大學
土壤環境科學系所
95
Li/Al-Layered double hydroxides (Li/Al-LDHs) can be synthesized by intercalating Li+ salt into the structure of Al(OH)3 layer. In the structure of Li/Al-LDH, Li+ ions occupy the vacant sites in the dioctahedral Al(OH)3 layers. As a result, Li/Al-LDHs have high anion exchange capacity, and have been investigated for its potential applications as anion adsorbents. Li/Al-LDHs have been synthesized with a wide variety of anions, whose physical and chemical properties may play an important role in determing the structural stability of Li/Al-LDHs. In this study, the deintercalation reactions of Li/Al-LDHs with various interlayer anions were investgated for the effects of radius, shape and hydration energy of those anions. The results showed that, in general, the larger the hydration radius, the higher the deintercalation rate. An inverse relationship between the activation energy of the reaction and the hydration radius of the interlayer anions was also found. Therefore, in addition to columbic interaction among the interlayer anions and the positively charged hydroxide layers of Li/Al-LDHs, the interaction between interlayer anions and water, and the size and shape of these anions also play an important role in determing Li+ stability in Li/Al-LDHs.
Chen, Rong-Jer, and 陳榮哲. "High-pressure Raman spectroscopy study of gibbsite." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/84596721526602728834.
Full text國立成功大學
地球科學系
83
High-pressure Raman spectra of gibbsite were studied up to 23.3 GPa, in diamond anvil cell at room temperature. 23 Raman- active modes were observed at ambient conditions and predominantly located in two regions: the lower-frequency region and the higher-frequency region. The wavenumber of modes in lower-frequency region (200 ~1200 cm-1) increases linearly with increasing pressure, with the slope of 0.4~7cm-1/ GPa up to 3.25 GPa. On the other hand,the OH-stetching modes show decreasing wavenumber while increasing pressure, in agreement with the general observations that OH bonds in hydrous phases become weakened under pressure, such as brucite and portlandite. Based on the observed Raman spectra under pressure region in the present study, significant variations occur at 2.7±0.5 GPa , where a phase transformation may take place for gibbsite.At pressures higher than 2.7±0.5 GPa, some Raman modes disappear and other new ones grow up with the slopes of new bands increasing to 2.5~10 cm-1/GPa. Raman spectrum of the after-compressed-sample is different from that of gibbsite, showing the new phase may have peresisted to the ambient conditions. Similar behavior in gibbsite was observed in EDXRD (Li et al., 1995), and, thus, it may indicate a reconstructive phase transformation at 2.7±0.5GPa. On the basis of the present data, no sign of dehydration occurring up to 23.3 GPa is indicated, and gibbsite sample after pressure release is likely consistent with the polymorphs of Al(OH)3 - nordstrandite.