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Journal articles on the topic 'Gibbsite'

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Author: Grafiati

Published: 4 June 2021

Last updated: 12 February 2022

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1

Gan, Bee K., Ian C. Madsen, and James G. Hockridge. "In situX-ray diffraction of the transformation of gibbsite to α-alumina through calcination: effect of particle size and heating rate." Journal of Applied Crystallography 42, no. 4 (June 30, 2009): 697–705. http://dx.doi.org/10.1107/s0021889809021232.

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A study was conducted on the gibbsite to α-alumina (α-Al2O3) transformation dynamics with particular reference to the influence of particle size and heating rate. Coarse- and fine-grained gibbsites were used to examine the transformation paths for the two materials, with particular reference to the upper and lower branch sequences described by Wefers & Misra [Oxides and Hydroxides of Aluminium, (1987), Alcoa Technical Paper No. 19 Revised, Aluminium Company of America]. The main techniques used to assess gibbsite calcination were thermogravimetric differential scanning calorimetry andin situX-ray diffraction, which provided complementary information on transformation behaviour. Whilst the quantitative phase analysis results indicated that the coarse- and fine-grained gibbsites followed both the upper and the lower branch sequences, detailed analysis of the results highlighted specific differences in the transformation behaviour for the two materials. With the loss of three molecules of water as gibbsite transformed to transition aluminas and finally α-Al2O3, there was a high degree of disorder in the crystal structure, resulting in broad and diffuse reflections in the diffraction patterns.

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2

Chandran, P., S. K. Ray, T. Bhattacharyya, P. Srivastava, P. Krishnan, and D. K. Pal. "Lateritic soils of Kerala, India: their mineralogy, genesis, and taxonomy." Soil Research 43, no. 7 (2005): 839. http://dx.doi.org/10.1071/sr04128.

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In this study, we report the chemical and mineralogical characteristics of 4 benchmark Ultisols of Kerala to elucidate their genesis and taxonomy. The taxonomic rationale of the mineralogy class of Ultisols and other highly weathered soils on the basis of the contemporary pedogenesis is also explained. The Ultisols of Kerala have low pH, low cation exchange capacity, low effective cation exchange capacity and base saturation, with dominant presence of 1 : 1 clays and gibbsite. Presence of gibbsite along with 2 : 1 minerals discounts the hypothesis of anti-gibbsite effect. Since the kaolins are interstratified with hydroxy-interlayered vermiculites (HIV), the formation of gibbsite from kaolinite is not tenable. Thus, gibbsite is formed from primary minerals in an earlier alkaline pedo-environment. Therefore, the presence of gibbsite does not necessarily indicate an advanced stage of weathering. On the basis of a dominant amount of gibbsite, a mineralogy class such as allitic or gibbsitic does not establish a legacy between the contemporary pedogenesis and the mineralogy. The dominance of kaolin–HIV in the fine clays of Ultisols and their persistence, possibly since early Tertiary, suggests that ‘steady state’ may exist in soils developed on long-term weathered saprolite. Since the present acid environment of Ultisols does not allow desilication, the chemical transformation of Ultisols to Oxisols with time is difficult to reconcile as envisaged in the traditional model of tropical soil genesis.

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3

Bhattacharyya, T., D. K. Pal, and P. Srivastava. "Formation of gibbsite in the presence of 2:1 minerals: an example from Ultisols of northeast India." Clay Minerals 35, no. 5 (December 2000): 827–40. http://dx.doi.org/10.1180/000985500547269.

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AbstractThere are two different views regarding the genesis of gibbsite in tropical acid soils: (1) direct weathering of primary Al-silicate minerals; and (2) transformation through clay mineral intermediates. We investigated the genesis of gibbsite in two representative Ultisols from northeastern India. Gibbsite in these Ultisols appears to be the remnant of earlier weathering products of aluminosilicate minerals formed in a neutral to alkaline pedochemical environment. The mere presence of gibbsite in these soils, therefore, does not indicate their advanced stage of weathering. The formation of typically rod-shaped and well-crystallized gibbsite in both the coarse and fine soil fractions in the presence of large amounts of 2:1 minerals indicates that the anti-gibbsite hypothesis may not be tenable in these tropical acid soils. A schematic model for the formation of gibbsite and kaolin in Ultisols is proposed.

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4

Vendrame, Pedro Rodolfo Siqueira, Robélio Leandro Marchão, Osmar Rodrigues Brito, Maria de Fátima Guimarães, and Thierry Becquer. "Relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture." Pesquisa Agropecuária Brasileira 44, no. 8 (August 2009): 996–1001. http://dx.doi.org/10.1590/s0100-204x2009000800031.

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The objective of this work was to assess the relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture. Twelve collection points were chosen in the Distrito Federal and in Formosa municipality, Goiás state, Brazil, representing four soil groups with varied levels of calcium + magnesium and kaolinite/(kaolinite + gibbsite) ratios. Soil macrofauna was collected in triplicate at each collection point, and identified at the level of taxonomic groups. Macrofauna density showed correlation with contents of kaolinite, gibbsite and exchangeable Ca + Mg in the soils. Mineralogy and exchangeable Ca + Mg had significant effects on taxonomic groups and relative density of soil macrofauna. The termites (Isoptera) were more abundant in soils with low exchangeable Ca + Mg; earthworms (Oligochaeta), in soils with high levels of kaolinite; and Hemiptera and Coleoptera larvae were more abundant in gibbsitic soils with higher contents of total carbon.

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5

Watling, Helen, Joanne Loh, and Helen Gatter. "Gibbsite crystallization inhibition." Hydrometallurgy 55, no. 3 (April 2000): 275–88. http://dx.doi.org/10.1016/s0304-386x(00)00061-x.

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6

Watling, Helen. "Gibbsite crystallization inhibition." Hydrometallurgy 55, no. 3 (April 2000): 289–309. http://dx.doi.org/10.1016/s0304-386x(00)00062-1.

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7

Frenzel, Johannes, Augusto F. Oliveira, Helio A. Duarte, Thomas Heine, and Gotthard Seifert. "Structural and Electronic Properties of Bulk Gibbsite and Gibbsite Surfaces." Zeitschrift f�r anorganische und allgemeine Chemie 631, no. 6-7 (May 2005): 1267–71. http://dx.doi.org/10.1002/zaac.200500051.

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8

Clemente, Celso Augusto, and Antonio Carlos de Azevedo. "Mineral weathering in acid saprolites from subtropical, southern Brazil." Scientia Agricola 64, no. 6 (December 2007): 601–7. http://dx.doi.org/10.1590/s0103-90162007000600007.

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Because weathering of minerals releases chemical elements into the biogeochemical cycle, characterization of their weathering products helps to better model groundwater quality, formation of secondary minerals and nutrient flux through the trophic chain. Based on microscopic and elemental analyses, weathering of riodacite from Serra Geral formation was characterized and weathering paths proposed. Three weathering paths of plagioclase phenocrystals were identified: plagioclase to gibbsite (Pg1); plagioclase to gels and gibbsite (Pg2); and plagioclase to gels, gibbsite and kaolinite (Pg3). Pyroxenes weathered to smectite and goethite (Py1), or to goethite and gibbsite (Py2), and magnetite weathered directly into iron oxides. Rock matrix comprises 90% of rock volume, and weathered to kaolinite and gibbsite, which explains why these minerals were the most abundant in the weathering products of these saprolites.

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9

Wu, Zheng Ping, Li Jiao Zhou, Qi Yuan Chen, and Zhou Lan Yin. "Reactive Ability and Bong Strength Analysis on Al(OH)₃ Crystals with Three Different Crystalline." Advanced Materials Research 396-398 (November 2011): 614–19. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.614.

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The crystal structure models of three kinds of different Al(OH)3 crystals, which are gibbsite, bayerite and nordstradite, are built respectively according to the corresponding experimental crystal lattice. Geometry optimizations are implemented by CASTEP program module using general gradient approximation (GGA) and local density approximation (LDA) methods respectively based on density functional theory (DFT). Total energy, electronic structure, atomic and bond populations are also calculated. The calculation results of total energy indicate that gibbsite is steadier than the other two from the point of view of energy, and the effect of basis set of GGA-PW91 is highest. At the same time, energy bond structure and density of states calculated at GGA-PW91 and LDA-CA-PZ levels show that the different of energy gap ΔE (ELUMO-EHOMO) at the first group of BZ is not obvious, and that the highest value of ΔE of gibbsite is more lower than the other two Al(OH)3 crystals. It may be likely to say that gibbsite may be more active than the other two crystals. According to the analysis of populations, it can be found that bond populations value of H-O and Al-O bonds of gibbsite is smallest in three different Al(OH)3 crystals, it is to say that the combination force of H-O and Al-O bonds of gibbsite is smallest and gibbsite may be more easier to be calcined theoretically.

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10

Wang, Jing, Qi Na He, and Zhen Gao. "The Effect of Different Solvent on the Microstructure of Gibbsite during Hydrothermal Treatment." Advanced Materials Research 160-162 (November 2010): 76–80. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.76.

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Phase structure and micromorphology of gibbsite after hydrothermal treated in different solvents were studied. Results showed that there was a relationship between micromorphology and phase structure of as-synthesized product. The cubic slice-like boehmite microstructure can be obtained in water. The 3D flowerlike boehmite microstructure can be obtained in isopropanol or sodium carbonate solution. The global ammonium aluminum carbonate hydroxide (AACH) architectures assembled by the lathes can be obtained in urea solvent. Gibbsite can transform to boehmite after 12h hydrothermal treatment in water. In isopropanol or sodium carbonate solution, this time decreased to 6h. In urea solution, Aluminum hydroxide turned from gibbsite to the mixture of boehmite, gibbsite and AACH. Finally, AACH is synthesized. This procedure needs 24h.

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11

Deyu, Li, Brian H. O'Connor, Gerald I. D. Roach, and John B. Cornell. "Use of X-Ray Powder Diffraction Rietveld Pattern-Fitting for Characterising Preferred Orientation in Gibbsites." Powder Diffraction 5, no. 2 (June 1990): 79–85. http://dx.doi.org/10.1017/s0885715600015384.

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AbstractA study has been conducted with gibbsite specimens, on the use of Rietveld X-ray powder diffraction (XRPD) pattern fitting for quantitating preferred orientation in powders. This study has shown that an earlier formula gives results which correlate closely with an empirical measure of morphology proposed recently for gibbsite powders, viz., the ratio of the XRPD intensities for the (002) line and the (110, 200) doublet lines. A method is proposed on the basis of this correlation for the correction for preferred orientation of line intensities in gibbsite powder patterns. The correction method appears to have excellent potential for XRPD quantification of gibbsite levels in mixtures, and could have general application for coping with preferred orientation effects in the quantitation of other phases.

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12

Torres Sánchez, Rosa M., A. Boix, and R. C. Mercader. "Grinding Assistance in the Transformation of Gibbsite to Corundum." Journal of Materials Research 17, no. 3 (March 2002): 712–17. http://dx.doi.org/10.1557/jmr.2002.0102.

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After gibbsite was milled for 5 min in a Cr-steel oscillating mill, corundum was obtained by heating the powder for 3 h at 800 °C. We found that iron contamination, produced by the milling process, is essential to attain the transformation at this low temperature and is located at the surface of the gibbsite particles. The knowledge of the oxidation state and location of the contaminant elements, necessary to control the solid-state reactions and/or phase transformations induced by the milling, was realized in this work by a characterization performed by chemical analysis, x-ray photoelectron spectroscopy, Mössbauer spectroscopy, and isoelectric point determination. The iron contamination amounted to about 3% (as Fe2O3) for the sample milled for 60 min. That the iron contamination that occurred mainly on the gibbsite amorphous surface was concluded after a comparison of the isoelectric point determination of the milled samples with that of a mechanical mixture of gibbsite and hematite. X-ray diffraction studies showed that gibbsite looses its crystallinity after the first 5 min of milling.

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13

Essington, Michael E., Julia B. Nelson, and William L. Holden. "Gibbsite and Goethite Solubility." Soil Science Society of America Journal 69, no. 4 (July 2005): 996–1008. http://dx.doi.org/10.2136/sssaj2004.0287.

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14

Phambu, Nsoki. "Adsorption of Carboxylic Acids on Submicrocrystalline Aluminum Hydroxides in Aqueous Solution. Part I: Qualitative Study by Infrared and Raman Spectroscopy." Applied Spectroscopy 56, no. 6 (June 2002): 756–61. http://dx.doi.org/10.1366/000370202760077496.

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Adsorption of acetic, oleic, benzoic, and salicylic acids on submicrocrystalline aluminum hydroxide samples is investigated in aqueous solutions. Experimental infrared and Raman spectroscopic data are analyzed to determine the reactivity of the monocoordinated hydroxyl groups located on the edge faces of bayerite or gibbsite crystals. Two key parameters were (1) the effect of concentration of aqueous solutions of the acids, and (2) the variation in specific surface areas of different samples of bayerite and gibbsite powders. Strong preferential adsorption to bayerite was observed over the whole pH range. No adsorption to gibbsite was detected. Data from the literature indicate that acetate, oleate, and benzoate form bidentate complexes on bayerite while salicylate forms a monodentate complex. The infrared spectra show that only monocoordinated hydroxyl groups are reactive, in the bayerite samples, and the band at 1020 cm−1 corresponds to the deformation mode of the monocoordinated hydroxyl groups whose stretching vibration was at 3465 cm−1. It is suggested that the specific surface areas given by the adsorption isotherms is a condition necessary for adsorption, but not sufficient in itself. Adsorption requires the presence of Al-OH2+1/2 species as well as the presence of steps or of a packaging sequence ABABABA rather than a packaging sequence ABBAABBA of the hydroxyl planes. The gibbsite impurity present in the bayerite sample reacted completely, while the lateral OH in the gibbsite sample did not, reflecting the lower reactivity in gibbsite relative to extended domains of bayerite.

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15

Varadachari, Chandrika, Tarit Chattopadhyay, and Kunal Ghosh. "The crystallo-chemistry of oxide-humus complexes." Soil Research 38, no. 4 (2000): 789. http://dx.doi.org/10.1071/sr99053.

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Complexation of humic substances with goethite, hematite, gibbsite, and boehmite has been explained from a viewpoint of crystal structure of the minerals. Theoretical analysis of crystal surface structures revealed the following. (i) Residual charge carried by O or OH on surfaces of gibbsite is –1/2; on boehmite it is –3/2 or –1/2; on goethite it is –4/3, –2/3, or –1/3; and on hematite it is –3/2, –1, or –1/2. Cations adsorbed to neutralise these charges can form bridging links with humic acid; higher charges form stronger links. (ii) Surfaces of goethite, hematite, and gibbsite also contain octahedral sites in which one O/OH position is vacant. These may provide centres for the formation of strong coordination bonds. (iii) Such vacant octahedral positions are absent in boehmite. It follows that in gibbsite, cation bridging links would be weak and vacant octahedral sites would be the dominant bonding sites; in goethite and hematite, both cation bridging and surface coordination sites would be present; in boehmite, cation bridging would be the only strong bonding mode. Derivations from crystallochemical analysis are supported by experimental observations. Infrared studies also show strong OH involvement in boehmite complexation in contrast to the weakness of OH involvement in gibbsite complexes.

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16

Yang, Hui-bin, Feng-qin Liu, Hong-liang Zhao, and Rui Wu. "Hydrothermal process of synthetic gibbsite and the characteristics of Na in gibbsite crystal." Chemical Papers 72, no. 12 (July 10, 2018): 3169–78. http://dx.doi.org/10.1007/s11696-018-0551-2.

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17

Hao, X., C. M. Cho, and G. J. Racz. "Chemical retardation of phosphate diffusion in simulated acid soil amended with lignosulfonate." Canadian Journal of Soil Science 80, no. 2 (May 1, 2000): 289–99. http://dx.doi.org/10.4141/s99-062.

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The availability and movement of inorganic phosphate fertilizer is usually low due to precipitation and adsorption reactions in soil. Lignosulfonate (LS), which is produced from acid sulfite pulping processes, has similar characteristics to soil organic materials. An experiment was designed to study the effects of LS on P movement in a simulated acid soil containing aluminum-saturated cation exchange resin and acid-washed fine sand. The resulting simulated soil had a cation exchange capacity of 22 cmolc kg−1 and either no or 10 g kg−1 gibbsite. Movement of surface-applied monopotassium phosphate was studied in soil columns, either with 20 g kg−1 LS or without LS. Lignosulfonate reduced phosphate fixation and sustained a higher water extractable phosphate concentration near the surface of the columns, but had no effect on downward phosphate movement in the columns with gibbsite. Lignosulfonate reduced the solution concentration of P near the surface and reduced downward phosphate movement in the columns without gibbsite. The resin-sand column with gibbsite closely reflected an acid soil, and this research showed that adding LS would increase fertilizer P availability in a gibbsite-rich acid soil. Adding Ca-LS to Al-rich soil is beneficial for another reason, improving Ca nutrition, which is poor for these soils. Key words: Chemical retardation, phosphate diffusion, lignosulfonate amendment

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18

Lloyd, S., S. M. Thurgate, R. M. Cornell, and G. M. Parkinson. "Atomic force microscopy of gibbsite." Applied Surface Science 135, no. 1-4 (September 1998): 178–82. http://dx.doi.org/10.1016/s0169-4332(98)00283-9.

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19

Enright, Eoin P., Teresa Curtin, John Haines, and Kenneth T. Stanton. "Gibbsite scaling on polymer surfaces." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 227, no. 3 (September 27, 2012): 196–207. http://dx.doi.org/10.1177/1464420712461220.

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20

Kingsley, Jeffrey P., and William R. Wilcox. "Adsorption of oxalate on gibbsite." Hydrometallurgy 16, no. 1 (April 1986): 105–7. http://dx.doi.org/10.1016/0304-386x(86)90055-1.

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21

Briley, Elizabeth, Patricia Huestis, X. Zhang, K. M. Rosso, and Jay A. LaVerne. "Radiolysis of thermally dehydrated gibbsite." Materials Chemistry and Physics 271 (October 2021): 124885. http://dx.doi.org/10.1016/j.matchemphys.2021.124885.

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22

Webster, Nathan A. S., Ian C. Madsen, Melissa J. Loan, Robert B. Knott, Fatima Naim, Kia S. Wallwork, and Justin A. Kimpton. "An investigation of goethite-seeded Al(OH)3precipitation usingin situX-ray diffraction and Rietveld-based quantitative phase analysis." Journal of Applied Crystallography 43, no. 3 (April 15, 2010): 466–72. http://dx.doi.org/10.1107/s0021889810008484.

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Anin situX-ray diffraction investigation of goethite-seeded Al(OH)3precipitation from synthetic Bayer liquor at 343 K has been performed. The presence of iron oxides and oxyhydroxides in the Bayer process has implications for alumina reversion, which causes significant process losses through unwanted gibbsite precipitation, and is also relevant for the nucleation and growth of scale on mild steel process equipment. The gibbsite, bayerite and nordstrandite polymorphs of Al(OH)3precipitated from the liquor; gibbsite appeared to precipitate first, with subsequent formation of bayerite and nordstrandite. A Rietveld-based approach to quantitative phase analysis was implemented for the determination of absolute phase abundances as a function of time, from which kinetic information for the formation of the Al(OH)3phases was determined.

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23

Camargo, Livia Arantes, José Marques Júnior, and Gener Tadeu Pereira. "Mineralogy of the clay fraction of Alfisols in two slope curvatures: III - spatial variability." Revista Brasileira de Ciência do Solo 37, no. 2 (April 2013): 295–306. http://dx.doi.org/10.1590/s0100-06832013000200001.

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A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, two 100 × 100 m grids were used to establish a total of 121 regularly spaced georeferenced sampling nodes 10 m apart. Samples were collected from the layer 0.0-0.2 m and analysed for iron oxides, and kaolinite and gibbsite in the clay fraction. Minerals in the clay fraction were characterized from their X-ray diffraction (XRD) patterns, which were interpreted and used to calculate the width at half height (WHH) and mean crystallite dimension (MCD) of iron oxides, kaolinite, and gibbsite, as well as aluminium substitution and specific surface area (SSA) in hematite and goethite. Additional calculations included the goethite and hematite contents, and the goethite/(goethite+hematite) [Gt/(Gt+Hm)] and kaolinite/(kaolinite+gibbsite) [Kt/(Kt+Gb)] ratios. Mineral properties were established by statistical analysis of the XRD data, and spatial dependence was assessed geostatistically. Mineralogical properties differed significantly between the convex area and concave area. The geostatistical analysis showed a greater number of mineralogical properties with spatial dependence and a higher range in the convex than in the concave area.

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24

Kew, G. A., and R. J. Gilkes. "Properties of regolith beneath lateritic bauxite in the Darling Range of south Western Australia." Soil Research 45, no. 3 (2007): 164. http://dx.doi.org/10.1071/sr06128.

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A morphological key has been developed for regolith that is exposed during mining of lateritic bauxite in the Darling Range of south Western Australia. The key distinguishes materials with different mineralogical and chemical properties. Iron oxide cemented (Zh) regolith has a gibbsitic matrix, quartz-rich (Zm) regolith has a gibbsite and kaolin matrix, and clay-rich (Zp) regolith has a kaolin matrix. An Si affinity element map (Si, Hf, Th) and a K affinity element group (K, Ba, Rb) are associated with granitic quartz-rich regolith and an Al/Fe element affinity group (Al, Fe, Ti, P, Ni, Co, Cu, Mn, Zn, Ga, Cr, V) is associated with clay and iron rich regolith. Doleritic regolith is generally associated with the Al/Fe affinity group. Although granite and granitic regolith exhibit similar element affinity groups, the abundance of elements within each is highly variable, which reflects the diversity in composition of granite within the region. The degree of euhedral character of clay-size platy crystals (kaolinite/gibbsite) does not differ for materials distinguished by the key, as both quartz-rich (Zm) and clay-rich (Zp) regolith and both granitic and doleritic saprolite contain subhedral kaolin crystals. The crystal size of platy kaolin (approximately 0.5 µm) is similar for different mine pits and for different regolith materials (Zm and Zp) within mine pits. There is a difference in halloysite tube length (0.52–1.18 µm) between mine pits, which may be related to the presence of weathered mica or to the alteration of halloysite in gibbsite-rich regolith. The internal and external diameters of halloysite tubes (about 0.11 and 0.24 µm) are similar for different mine pits and different regolith types within mine pits. The resin used during thin section preparation contains chlorine, so that determination of chlorine by EMPA provides a measure of the porosity of regolith material. A systematic negative relationship exists between chlorine concentration and total oxide weight % of porous regolith matrix determined by EMPA; both measurements provide an indication of the porosity of the clay matrix in regolith.

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25

Oliveira, F. S., A. F. D. C. Varajão, C. A. C. Varajão, and B. Boulangé. "A comparison of properties of clay minerals in isalteritic and in degraded facies." Clay Minerals 48, no. 5 (December 2013): 697–711. http://dx.doi.org/10.1180/claymin.2013.048.5.03.

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AbstractThe mineralogical, geochemical and micromorphological features of an isalteritic clay facies, which originated from weathering of an anorthosite, were compared to those of clay facies derived from the degradation of a bauxite developed from the same rock. The isalteritic clay was formed by the hydrolytic alteration of plagioclase, whereas the degraded clays were formed by decomposition of gibbsite and neoformation of kaolinite. This resilification process resulted from the reintroduction of silica via the oscillation of the phreatic level and/or the decomposition of organic matter on the surface. The degradation process was gradual and yielded two different facies: (a) degraded clays with almost total decomposition of gibbsite, and (b) degraded clays with gibbsite nodules. Morphologically, the isalteritic clays differ from the degraded clays because they contain larger hexagonal and pseudo-hexagonal crystals. The degraded clays have more irregular crystal shapes, ranging from laths to anhedral shapes.

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26

Srisawad, Natpakan, Wasu Chaitree, Okorn Mekasuwandumrong, Piyasan Praserthdam, and Joongjai Panpranot. "Formation of CoAl2O4Nanoparticles via Low-Temperature Solid-State Reaction of Fine Gibbsite and Cobalt Precursor." Journal of Nanomaterials 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/108369.

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Nanocrystalline cobalt aluminate (CoAl2O4) was synthesized by the solid-state reaction method with cobalt chloride hexahydrate (CoCl2 · 6H2O) as the source of Co and gibbsite (Al(OH)3) as the source of Al, respectively. The effects of particle size of the starting fine gibbsite (0.6 and 13 μm) and calcination temperatures (450, 550, and 650°C) on the properties of CoAl2O4were investigated by means of X-ray diffraction (XRD), thermogravimetry analysis and differential thermal analysis (TG/DTA), X-ray photoelectron spectroscopy (XPS), UV-visible absorption spectroscopy (UV-Vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Increasing of calcination temperature promoted the insertion amounts of Co2+in alumina matrix in CoAl2O4structure, which resulted in the brighter blue particles and increasing of UV spectra band. The lowest temperature for the formation of nanocrystalline CoAl2O4particles was 550°C for the solid-state reaction of cobalt chloride and 0.6 μm fine gibbsite.

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27

Meshcheryakov, Eugene P., Sergey I. Reshetnikov, Mariya P. Sandu, Alexey S. Knyazev, and Irina A. Kurzina. "Efficient Adsorbent-Desiccant Based on Aluminium Oxide." Applied Sciences 11, no. 6 (March 10, 2021): 2457. http://dx.doi.org/10.3390/app11062457.

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The review describes the main methods of obtaining hydroxides and aluminium oxides (AO) of various structures from gibbsite. The promising techniques of obtaining AO adsorbents are discussed, namely the technique of thermal activation in the mode of pneumatic transport with gibbsite by heated air (TCA Gb) and the technique of thermal activation of gibbsite in centrifugal flash reactors (CTA Gb). The main methods of improving the adsorbent properties of AO, such as the optimisation of texture characteristics and phase composition, as well as the influence of the modification of aluminium oxide adsorbents, obtained using CTA and TCA technologies with cations of alkaline metals, are considered. It is shown that the modification allows a controlled variation of the characteristics of donor and acceptor active sites on the surface of adsorbents and, thus, a substantial increase in their adsorption activity, in particular, with respect to water vapour.

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28

Bonato, J. A., and R. J. Morrison. "Weathering, bauxitisation and soil genesis from the Nakobalevu Basalt, South-East Viti Levu, Fiji." South Pacific Journal of Natural and Applied Sciences 30, no. 1 (2012): 1. http://dx.doi.org/10.1071/sp12001.

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The augite-olivine flows (5.3 Ma) capping Mount Nakobalevu, a few kilometres north-west of Suva, Fiji, have been subjected to rapid and deep weathering. The Nakobalevu K1 and K2 weathering profiles (at approximately 454 m altitude) show features of strong bauxitisation, and the attributes of a 'classical' lateritic profile. Aluminium and iron enrichment in the 2-3 m depth layers of the Nakobalevu weathering profiles is marked, with the presence of abundant gibbsite (as gravels and nodules, and in the silt and clay-sized fractions), goethite, kaolinite, haematite and magnetite (grains); the presence of fragmented (goethitic and gibbsitic) crustal materials in each of the studied horizons, and the distribution pattern of the Al2O3, Fe2O3 and SiO2, would infer the occurrence of several erosion and weathering cycles, some of which would have evolved under drier climatic regimes. Using Soil Taxonomy, the Nakobalevu Pedon (JBK-1) is a Typic Kandihumult, clayey, kaolinitic, isohyperthermic, which does not give any indication of the gibbsitic materials present.

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29

Savko, A. D., V. M. Novikov, N. M. Boeva, A. V. Krainov, A. V. Milash, E. A. Zhegallo, M. Yu Ovchinnikova, and N. S. Bortnikov. "Mamon stratum of the upper devonian of the Voronezh anteclise - new kaolin-bearing province." Доклады Академии наук 489, no. 6 (December 23, 2019): 621–25. http://dx.doi.org/10.31857/s0869-56524896621-625.

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The lithofacies analysis of the Mamon showed showed that secondary kaolin deposits, forming a new kaolin-bearing province in the southern part of the Voronezh anteklise, are associated with a complex of deluvial-proluvial, lacustrine-boggy, and floodplain-oxbow deposits. The main ore minerals are kaolinite, quartz and secondary iron oxides and gibbsite. The presence of both terrigenous and autistic kaolinite was revealed. An important role in the formation of the latter, as well as gibbsite, played an organic substance.

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30

Ding, Yuan Fa, Xiang Dong Su, Da Qiao Hu, Jian Kang Liu, Li He, and Dan Ning Li. "Experimental Study of Solid Dispersion in a Seeded Precipitation Tank with Slight Agitation for Gibbsite Crystallization." Applied Mechanics and Materials 456 (October 2013): 537–40. http://dx.doi.org/10.4028/www.scientific.net/amm.456.537.

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In order to explore the energy saving measures in gibbsite crystallization process for alumina production by Bayer method, industrial experiment was carried out to investigate the solid dispersion in a slight agitation seed precipitation tank for gibbsite crystallization. The experimental results showed that little difference of solid concentration, only 48.19 g·l-1is found in the range from 5 meters depth to the tank bottom, which is the most zone of the tank, and there is a somewhat large difference in the top 5 meters zone near the surface that is about 149.66 g·l-1. Therefore, under the condition of slight agitation, solid content would not concentrate to the tank bottom completely with the normal work flow. It is suggested that the work of production would not be interrupted in less agitation than before, and the electrical energy saving rate is about 34%. The effects of reduced agitation on the yield and the quality of gibbsite crystallization should be studied carefully in subsequent works.

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31

Rozic, Ljiljana, Tatjana Novakovic, Nadezda Jovanovic, Ana Terlecki-Baricevic, and Zeljko Grbavcic. "The kinetics of the partial dehydration of gibbsite to activated alumina in a reactor for pneumatic transport." Journal of the Serbian Chemical Society 66, no. 4 (2001): 273–80. http://dx.doi.org/10.2298/jsc0104273r.

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The dehidration kinetics of gibbsite to activated alumina was investigated at four different temperatures between 883 K and 943 K in a reactor for pneumatic transport in the dilute two phase flow regime. The first order kinetic behavior of this reactionwith respect to the water content of the solid material was proved and an activation energy of 66.5 kJ/mol was calculated. The effect of residence time on the water content is given and compared with theoretical calculations. The water content and other characteristics of the products depend on two main parameters, one is the short residence time and the other is the temperature of the dehydration of gibbsite. The short residence time of the gibbsite particles in a reactor for pneumatic transport prevents crystallization into new phases, as established from XRD analysis data. Reactive amorphous alumina powder, with a specific surface area of 250 m2/g, suitable as a precursor for catalyst supports is obtained.

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32

Kitamura, Makoto, and Mamoru Senna. "Electrorheological properties of mechanically activated gibbsite." International Journal of Inorganic Materials 3, no. 6 (September 2001): 563–67. http://dx.doi.org/10.1016/s1466-6049(01)00068-x.

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33

Wijnhoven, Judith E. G. J. "Coating of Gibbsite Platelets with Silica." Chemistry of Materials 16, no. 20 (October 2004): 3821–28. http://dx.doi.org/10.1021/cm049437m.

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34

MacKenzie, K. J. D., J. Temuujin, and K. Okada. "Thermal decomposition of mechanically activated gibbsite." Thermochimica Acta 327, no. 1-2 (March 1999): 103–8. http://dx.doi.org/10.1016/s0040-6031(98)00609-1.

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35

Ogata, Fumihiko, Naohito Kawasaki, Mineaki Kabayama, Takeo Nakamura, and Seiki Tanada. "Structure Transformation of Gibbsite by Calcination." e-Journal of Surface Science and Nanotechnology 4 (2006): 267–69. http://dx.doi.org/10.1380/ejssnt.2006.267.

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36

Liu, Ye, Ding Ma, Ross A. Blackley, Wuzong Zhou, Xiuwen Han, and Xinhe Bao. "Synthesis and Characterization of Gibbsite Nanostructures." Journal of Physical Chemistry C 112, no. 11 (February 23, 2008): 4124–28. http://dx.doi.org/10.1021/jp7101572.

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37

Belaroui, K., M. N. Pons, and H. Vivier. "Morphological characterisation of gibbsite and alumina." Powder Technology 127, no. 3 (November 2002): 246–56. http://dx.doi.org/10.1016/s0032-5910(02)00112-2.

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38

Fleming, Sean D., Andrew L. Rohl, Steve C. Parker, and Gordon M. Parkinson. "Atomistic Modeling of Gibbsite: Cation Incorporation." Journal of Physical Chemistry B 105, no. 22 (June 2001): 5099–105. http://dx.doi.org/10.1021/jp003136s.

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39

Lawrence, William T., Robert J. Lauf, and Dixie L. Barker. "Fluorescent Gibbsite from Yunnan Province, China." Rocks & Minerals 78, no. 2 (April 2003): 110–11. http://dx.doi.org/10.1080/00357529.2003.9926703.

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40

Adu-Wusu, Kofi, and William R. Wilcox. "The removal of silicate from gibbsite." Hydrometallurgy 32, no. 1 (January 1993): 111–17. http://dx.doi.org/10.1016/0304-386x(93)90060-q.

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41

Rakshit, Sudipta, Dibyendu Sarkar, Pravin Punamiya, and Rupali Datta. "Antimony sorption at gibbsite–water interface." Chemosphere 84, no. 4 (July 2011): 480–83. http://dx.doi.org/10.1016/j.chemosphere.2011.03.028.

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42

Adu-Wusu, Kofi, and William R. Wilcox. "Kinetics of silicate reaction with gibbsite." Journal of Colloid and Interface Science 143, no. 1 (April 1991): 127–38. http://dx.doi.org/10.1016/0021-9797(91)90445-e.

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43

Mehta, S. K., and A. Kalsotra. "Kinetics and hydrothermal transformation of gibbsite." Journal of Thermal Analysis 37, no. 2 (February 1991): 267–75. http://dx.doi.org/10.1007/bf02055929.

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44

Meor Sulaiman, Meor Yusoff, Khaironie Mohamed Takip, Nur Aqilah Sapiee, and Ahmad Khairulikram Zahari. "Synthesis of Aluminium Hydroxide and Alumina by Hydrothermal and Solvothermal Methods." Materials Science Forum 840 (January 2016): 359–63. http://dx.doi.org/10.4028/www.scientific.net/msf.840.359.

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The paper describes some work done on the SEM and XRD characteristic studies of aluminium hydroxide and alumina synthesized by the solvothermal and hydrothermal methods. Hydrothermal process produced boehmite phase aluminium hydroxide while the solvothermal process produced gibbsite phase aluminium hydroxide. Transition reaction study by in-situ XRD shows that the gibbsite is transformed into boehmite before it is converted into alumina. This transformation stage involves a dissolution-recrystallization process. The SEM results show the changes in morphology of the crystals as a result of both these processes.

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45

Wang, Suyun, Xin Zhang, Trent R. Graham, Hailin Zhang, Carolyn I. Pearce, Zheming Wang, Sue B. Clark, Wei Jiang, and Kevin M. Rosso. "Two-step route to size and shape controlled gibbsite nanoplates and the crystal growth mechanism." CrystEngComm 22, no. 15 (2020): 2555–65. http://dx.doi.org/10.1039/d0ce00114g.

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46

Loiko, Olessya P., Anne B. Spoelstra, Alexander M. van Herk, Jan Meuldijk, and Johan P. A. Heuts. "ATRP mediated encapsulation of Gibbsite: fixation of the morphology by using a cross-linker." Polymer Chemistry 8, no. 19 (2017): 2909–12. http://dx.doi.org/10.1039/c7py00226b.

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47

Vendrame, P. R. S., O. R. Brito, E. S. Martins, C. Quantin, M. F. Guimarães, and T. Becquer. "Acidity control in Latosols under long-term pastures in the Cerrado region, Brazil." Soil Research 51, no. 4 (2013): 253. http://dx.doi.org/10.1071/sr12214.

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High acidity and aluminium saturation are among the main limiting factors for crop production in tropical soils. The aim of this work was to measure the acidity of Latosols under pastures in the Brazilian Cerrado and to assess the influence of clay mineralogy as a controlling parameter of soil acidity. Topsoils (n = 73, 0–0.2 m depth) of Latosols developed on different parent materials were sampled in two sub-regions of the Cerrado region. The main chemical characteristics were determined by standard procedures, and kaolinite and gibbsite contents were determined by dissolution with sulfuric acid and thermogravimetric analyses. The exchangeable concentrations of calcium (Ca), magnesium (Mg), and potassium (K) varied considerably among soil samples, with ranges of 0–13.9 cmolc kg–1 (mean ± standard deviation 1.77 ± 1.91 cmolc kg–1) for Ca; 0.2–3.2 cmolc kg–1 (1.13 ± 0.68 cmolc kg–1) for Mg; and 0–1.0 cmolc kg–1 (0.24 ± 0.24 cmolc kg–1) for K. The mean concentration of exchangeable aluminium (Al) was 0.55 ± 0.61 cmolc kg–1 (range 0–2.3 cmolc kg–1). The content of kaolinite (282 ± 96 g kg–1) was higher than of gibbsite (106 ± 77 g kg–1). The amount of exchangeable Al and Al saturation rate varied according to the mineralogy of the clay fraction of the soils. The content of exchangeable Al3+ remained low when gibbsite was the predominant mineral, whereas it increased with kaolinite content. The ratio kaolinite/(kaolinite + gibbsite) could be used as a useful indicator of the sensitivity of soils affected by acidity and Al toxicity.

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48

Antelo, Juan, Sarah Fiol, Silvia Mariño, Florencio Arce, Dora Gondar, and Rocio Lopez. "Copper adsorption on humic acid coated gibbsite: comparison with single sorbent systems." Environmental Chemistry 6, no. 6 (2009): 535. http://dx.doi.org/10.1071/en09066.

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Environmental context. Adsorption processes control the mobility and bioavailability of nutrients and contaminants in soils, sediments and aquatic systems. Natural organic matter and aluminium oxides are important reactive materials present in natural systems and their mutual interaction may alter the surface properties of both materials, playing an important role on the fate of different contaminants, such as copper, in the environment. The present study illustrates the importance of these interactions, showing that the presence of natural organic matter has a synergic effect on the copper adsorption on the aluminium oxide surface. Abstract. Copper adsorption processes on aluminium oxides may significantly control the mobility and transport of copper ions in soils and surface waters. The binding of protons and copper to humic acid (HA) and to gibbsite as single sorbent systems was investigated and the results then used to test the validity of the Linear Additivity Model (LAM) for describing copper binding to gibbsite/HA systems. More copper was adsorbed in the gibbsite/HA/Cu2+ ternary system, at pH 4 and 6 and ionic strength 0.1 M, than in the corresponding binary systems. Although copper adsorption on gibbsite at pH 4 is rather small, the enhancement in sorption was noteworthy, and can be attributed to the formation of ternary complexes and changes in the electrostatic potentials at the mineral surface or at the HA as a result of their mutual interaction. The LAM predicted satisfactorily the experimental results at pH 6, whereas it underestimated the copper binding at pH 4.

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49

Varajão, Angélica F. Drummond C., Robert J. Gilkes, and Robert D. Hart. "Amorphous alumino-silicate materials in a Brazilian hydromorphic lateritic soil." Soil Research 40, no. 3 (2002): 465. http://dx.doi.org/10.1071/sr00008.

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Two ancient lateritic soil profiles from Brazil that are now experiencing hydromorphic conditions were investigated by chemical extractions, X-ray diffraction, differential thermal and thermogravimetric analysis, and analytical transmission electron microscopy (ATEM) to identify if the hydromorphic conditions had affected soil minerals. The soils are composed of gibbsite and kaolinite with less quartz, anatase, goethite, pedogenic chlorite, and amorphous alumino-silicate phases. These last 2 constituents occur in the middle and upper horizons of both soil profiles, together with considerable amounts of organic carbon. Analytical TEM showed that the amorphous phases enveloped corroded gibbsite and kaolinite crystals and may indicate the transformation of these minerals to amorphous phases. The amorphous phases have a similar microfabric to that of allophane and ATEM analyses of the amorphous phases gave an Al/Si atom ratio that was always >2, and commonly about 10. These atom ratios are consistent with the bulk chemical results obtained using pyrophosphate, oxalate, and dithionite extractants, but not with the theoretical ratio for allophane. The Al/Si atom ratio of the amorphous phases was related to the Al content of the mineral enveloped by the amorphous phases, i.e. gibbsite or kaolinite. This association supports the interpretation that the amorphous phases formed from the crystalline minerals. The saturated condition of the profiles, together with the high concentration of organic matter in the upper horizons, favours dissolution of the original gibbsite and kaolinite in the laterite and their transformation to amorphous alumino-silicate phases with a high Al content.

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50

O'Connor, B. H., D. Y. Li, and H. Sitepu. "Texture Characterisation in X-Ray Powder Diffraction using the March Formula." Advances in X-ray Analysis 35, A (1991): 277–83. http://dx.doi.org/10.1154/s0376030800008922.

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AbstractTexture, i.e. preferred orientation (PO), of crystallites can cause serious systematic errors in quantitative analysis of crystalline materials using x-ray powder diffraction (XRPD) data. The singleparameter model of March (1932), proposed by Dollase (1986) for use in powder diffractometry is a promising mathematical formalism for correcting PO in XRPD analysis of uniaxially-oriented specimens. O'Connor et al. (1991) successfully applied the March formula in applying preferred orientation corrections for gibbsites, Al(OH)3, using Rietveld pattern-fitting and a line ratio method in which corrections are determined according to the intensity ratios of selected lines. The paper gives an appraisal of the general applicability of the methods considered by Li and O'Connor with particular reference to powder diffraction data for gibbsite, molybdite (MoO3), calcite (CaCO3) and kaolinite specimens. It is shown that some caution should be exercised when using the March formula to describe PO in Rietveld analysis.

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