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Huada Ruan - One of the best experts on this subject based on the ideXlab platform.
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thermal decomposition of bauxite minerals infrared emission spectroscopy of Gibbsite boehmite and diaspore
Journal of Materials Science, 2002Co-Authors: J. Theo Kloprogge, Huada Ruan, Ray L FrostAbstract:Infrared emission spectroscopy has been used to study the dehydroxylation behavior over the temperature range from 200 to 750°C of three major Al-minerals in bauxite: Gibbsite (synthetic and natural), boehmite (synthetic and natural) and diaspore. A good agreement is found with the thermal analysis and differential thermal analysis curves of these minerals. Loss in intensity of especially the hydroxyl-stretching modes of Gibbsite, boehmite and diaspore as function of temperature correspond well with the observed changes in the TGA/DTA patterns. The DTA pattern of Gibbsite clearly indicates the formation of boehmite as an intermediate shown by a endotherm around 500°C. Dehydroxylation of Gibbsite is followed by a loss of intensity of the 3620 and 3351 cm−1 OH-stretching bands and the corresponding deformation band around 1024 cm−1. Dehydroxylation starts around 220°C and is complete around 350°C. Similar observations were made for boehmite and diaspore. For boehmite dehydroxylation was observed to commence around 250°C and could be followed by especially the loss in intensity of the bands around 3319 and 3129 cm−1. The DTA pattern of diaspore is more complex with overlapping endotherms around 622 and 650°C. The dehydroxylation can be followed by the decrease in intensity of the OH-stretching bands around 3667, 3215 and 2972 cm−1. Above 550°C only a single band is observed that disappears after heating above 600°C corresponding to the two endotherms around 622 and 650°C in the DTA.
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comparison of the raman spectra of bayerite boehmite diaspore and Gibbsite
Journal of Raman Spectroscopy, 2001Co-Authors: Huada Ruan, Theo J KloproggeAbstract:Gibbsite and bayerite are alumina trihydrate (Al(OH) 3). Gibbsite occurs abundantly in nature, usually as a major mineral component in bauxite whereas bayerite is rarely found in nature. Boehmite and diaspore are alumina oxohydroxide (AlOOH) and are two other important minerals in bauxite. The Raman spectra of these four minerals were obtained using a Fourier transform Raman spectrometer operating at 1064 nm. Bayerite spectrum shows five absorption bands, 3652, 3542, 3449, 3438, and 3421 cm-1 and the Gibbsite spectrum shows four strong and sharp absorption bands, 3619, 3523, 3433 and 3363 cm-1 in the hydroxyl stretching region. Four broad bands, 3426, 3365, 3229 and 2935 cm-1 and three weak bands, 3420, 3216 and 3090 cm-1 are present in this region for diaspore and boehmite, respectively. The Raman bands correspond well with the infrared absorption bands at 3620, 3525 cm-1 for Gibbsite, 3365 cm-1 for diaspore and 3423, 3096 cm-1 for boehmite and these bands are assigned to be Raman and infrared active. The spectra of bayerite, Gibbsite and diaspore are complex while the spectrum of boehmite only illustrates four absorption bands in the low frequency region. Common bands of RT-Raman spectra at 1019, 892, 816, 710, 568, 539, 506, 429, 395, 379, 321, 306, 255 and 242 cm-1 were observed for Gibbsite, 1079, 1068, 898, 866, 545, 434, 388, 322, 292, 250 and 239 cm-1 for bayerite, 705, 608, 446, 260 and 216 cm-1 for diaspore, and 674, 495 and 360 cm-1 for boehmite. The differences in the vibrational spectra of bayerite, Gibbsite, diaspore and boehmite are interpreted as being due to the differences in the molecular structure of these minerals.
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comparison of raman spectra in characterizing Gibbsite bayerite diaspore and boehmite
Journal of Raman Spectroscopy, 2001Co-Authors: Huada Ruan, J. Theo KloproggeAbstract:High-quality Raman spectra were used for the characterization of alumina phases of Gibbsite, bayerite, diaspore and boehmite. The Raman spectrum of Gibbsite shows four strong, sharp bands at 3617, 3522, 3433 and 3364 cm in the hydroxyl stretching region. The spectrum of bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm. Five broad bands at 3445, 3363, 3226, 3119 and 2936 cm and four broad and weak bands at 3371, 3220, 3085 and 2989 cm-1 are present in the Raman spectrum of the hydroxyl stretching region of diaspore and boehmite. The hydroxyl stretching bands are related to the surface structure of the minerals. The Raman spectra of bayerite, Gibbsite and diaspore are complex whereas the Raman spectrum of boehmite shows only four bands in the low-wavenumber region. These bands are assigned to deformation and translational modes of the alumina phases. A comparison of the Raman spectrum of bauxite with those of boehmite and Gibbsite showed the possibility of using Raman spectroscopy for on-line processing of bauxites that contain a mixture of alumina phases.
Jirawat Runglerttrakoolchai - One of the best experts on this subject based on the ideXlab platform.
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solid phase speciation and solubility of phosphorus in an acid sulfate paddy soil during soil reduction and reoxidation as affected by oil palm ash and biochar
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Worachart Wisawapipat, Kamolchanok Charoensri, Jirawat RunglerttrakoolchaiAbstract:Understanding phosphorus (P) speciation and how redox conditions control P solubility in acid sulfate paddy soils with limited P availability is crucial for improving soil P availability. We examined P speciation and extractability in an acid sulfate paddy soil incorporated with oil palm ash (OPA) and biochar (OPB) during soil reduction and subsequent oxidation. Phosphorus K-edge X-ray absorption near edge structure (XANES) spectra of the soil samples revealed that P in the soil mainly occurred as P adsorbed to ferrihydrite and P adsorbed to Gibbsite. During soil reduction, Gibbsite-bound P was transformed into variscite, which was back-transformed to Gibbsite-bound P during soil reoxidation. Sequential extraction results confirmed the dominance of Fe/Al (hydr)oxides-bound P (average 72%) in the soils. The OPA incorporation increased the exchangeable P pool concurring with the decrease in Gibbsite-bound P. The OPB incorporation enhanced the dissolved P from the residual pool presumably due to electron shu...
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Solid-Phase Speciation and Solubility of Phosphorus in an Acid Sulfate Paddy Soil during Soil Reduction and Reoxidation as Affected by Oil Palm Ash and Biochar
2017Co-Authors: Worachart Wisawapipat, Kamolchanok Charoensri, Jirawat RunglerttrakoolchaiAbstract:Understanding phosphorus (P) speciation and how redox conditions control P solubility in acid sulfate paddy soils with limited P availability is crucial for improving soil P availability. We examined P speciation and extractability in an acid sulfate paddy soil incorporated with oil palm ash (OPA) and biochar (OPB) during soil reduction and subsequent oxidation. Phosphorus K-edge X-ray absorption near edge structure (XANES) spectra of the soil samples revealed that P in the soil mainly occurred as P adsorbed to ferrihydrite and P adsorbed to Gibbsite. During soil reduction, Gibbsite-bound P was transformed into variscite, which was back-transformed to Gibbsite-bound P during soil reoxidation. Sequential extraction results confirmed the dominance of Fe/Al (hydr)oxides-bound P (average 72%) in the soils. The OPA incorporation increased the exchangeable P pool concurring with the decrease in Gibbsite-bound P. The OPB incorporation enhanced the dissolved P from the residual pool presumably due to electron shuttling of biochar with Fe(III) minerals during soil reduction. Our results highlight P dynamics in paddy soils, which are of immense importance for effective P-management strategies in rice cultivation
J. Theo Kloprogge - One of the best experts on this subject based on the ideXlab platform.
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thermal decomposition of bauxite minerals infrared emission spectroscopy of Gibbsite boehmite and diaspore
Journal of Materials Science, 2002Co-Authors: J. Theo Kloprogge, Huada Ruan, Ray L FrostAbstract:Infrared emission spectroscopy has been used to study the dehydroxylation behavior over the temperature range from 200 to 750°C of three major Al-minerals in bauxite: Gibbsite (synthetic and natural), boehmite (synthetic and natural) and diaspore. A good agreement is found with the thermal analysis and differential thermal analysis curves of these minerals. Loss in intensity of especially the hydroxyl-stretching modes of Gibbsite, boehmite and diaspore as function of temperature correspond well with the observed changes in the TGA/DTA patterns. The DTA pattern of Gibbsite clearly indicates the formation of boehmite as an intermediate shown by a endotherm around 500°C. Dehydroxylation of Gibbsite is followed by a loss of intensity of the 3620 and 3351 cm−1 OH-stretching bands and the corresponding deformation band around 1024 cm−1. Dehydroxylation starts around 220°C and is complete around 350°C. Similar observations were made for boehmite and diaspore. For boehmite dehydroxylation was observed to commence around 250°C and could be followed by especially the loss in intensity of the bands around 3319 and 3129 cm−1. The DTA pattern of diaspore is more complex with overlapping endotherms around 622 and 650°C. The dehydroxylation can be followed by the decrease in intensity of the OH-stretching bands around 3667, 3215 and 2972 cm−1. Above 550°C only a single band is observed that disappears after heating above 600°C corresponding to the two endotherms around 622 and 650°C in the DTA.
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comparison of raman spectra in characterizing Gibbsite bayerite diaspore and boehmite
Journal of Raman Spectroscopy, 2001Co-Authors: Huada Ruan, J. Theo KloproggeAbstract:High-quality Raman spectra were used for the characterization of alumina phases of Gibbsite, bayerite, diaspore and boehmite. The Raman spectrum of Gibbsite shows four strong, sharp bands at 3617, 3522, 3433 and 3364 cm in the hydroxyl stretching region. The spectrum of bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm. Five broad bands at 3445, 3363, 3226, 3119 and 2936 cm and four broad and weak bands at 3371, 3220, 3085 and 2989 cm-1 are present in the Raman spectrum of the hydroxyl stretching region of diaspore and boehmite. The hydroxyl stretching bands are related to the surface structure of the minerals. The Raman spectra of bayerite, Gibbsite and diaspore are complex whereas the Raman spectrum of boehmite shows only four bands in the low-wavenumber region. These bands are assigned to deformation and translational modes of the alumina phases. A comparison of the Raman spectrum of bauxite with those of boehmite and Gibbsite showed the possibility of using Raman spectroscopy for on-line processing of bauxites that contain a mixture of alumina phases.
Worachart Wisawapipat - One of the best experts on this subject based on the ideXlab platform.
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solid phase speciation and solubility of phosphorus in an acid sulfate paddy soil during soil reduction and reoxidation as affected by oil palm ash and biochar
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Worachart Wisawapipat, Kamolchanok Charoensri, Jirawat RunglerttrakoolchaiAbstract:Understanding phosphorus (P) speciation and how redox conditions control P solubility in acid sulfate paddy soils with limited P availability is crucial for improving soil P availability. We examined P speciation and extractability in an acid sulfate paddy soil incorporated with oil palm ash (OPA) and biochar (OPB) during soil reduction and subsequent oxidation. Phosphorus K-edge X-ray absorption near edge structure (XANES) spectra of the soil samples revealed that P in the soil mainly occurred as P adsorbed to ferrihydrite and P adsorbed to Gibbsite. During soil reduction, Gibbsite-bound P was transformed into variscite, which was back-transformed to Gibbsite-bound P during soil reoxidation. Sequential extraction results confirmed the dominance of Fe/Al (hydr)oxides-bound P (average 72%) in the soils. The OPA incorporation increased the exchangeable P pool concurring with the decrease in Gibbsite-bound P. The OPB incorporation enhanced the dissolved P from the residual pool presumably due to electron shu...
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Solid-Phase Speciation and Solubility of Phosphorus in an Acid Sulfate Paddy Soil during Soil Reduction and Reoxidation as Affected by Oil Palm Ash and Biochar
2017Co-Authors: Worachart Wisawapipat, Kamolchanok Charoensri, Jirawat RunglerttrakoolchaiAbstract:Understanding phosphorus (P) speciation and how redox conditions control P solubility in acid sulfate paddy soils with limited P availability is crucial for improving soil P availability. We examined P speciation and extractability in an acid sulfate paddy soil incorporated with oil palm ash (OPA) and biochar (OPB) during soil reduction and subsequent oxidation. Phosphorus K-edge X-ray absorption near edge structure (XANES) spectra of the soil samples revealed that P in the soil mainly occurred as P adsorbed to ferrihydrite and P adsorbed to Gibbsite. During soil reduction, Gibbsite-bound P was transformed into variscite, which was back-transformed to Gibbsite-bound P during soil reoxidation. Sequential extraction results confirmed the dominance of Fe/Al (hydr)oxides-bound P (average 72%) in the soils. The OPA incorporation increased the exchangeable P pool concurring with the decrease in Gibbsite-bound P. The OPB incorporation enhanced the dissolved P from the residual pool presumably due to electron shuttling of biochar with Fe(III) minerals during soil reduction. Our results highlight P dynamics in paddy soils, which are of immense importance for effective P-management strategies in rice cultivation
Yi Zhang - One of the best experts on this subject based on the ideXlab platform.
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Crystallization and Phase Transformations of Aluminum (Oxy)hydroxide Polymorphs in Caustic Aqueous Solution
'American Chemical Society (ACS)', 2021Co-Authors: Zhang Hailin, Zhang Xin, Pearce Carolyn, Graham, Trent R., Hlushko Hanna, Laverne, Jay A., Liu Lili, Wang Suyun, Zheng Shili, Yi ZhangAbstract:Gibbsite, bayerite, and boehmite are important aluminum (oxy)-hydroxide minerals in nature and have been widely deployed in various industrial applications. They are also major components in caustic nuclear wastes stored at various U.S. locations. Knowledge of their crystallization and phase transformation processes contributes to understanding their occurrence and could help optimize waste treatment processes. While it has been reported that partial conversion of bayerite and Gibbsite to boehmite occurs in basic solutions at elevated temperatures, systematic studies of factors affecting the phase transformation as well as the underlying reaction mechanisms are nonexistent, particularly in highly alkaline solutions. We explored the effects of sodium hydroxide concentrations (0.1-3 M), reaction temperatures (60-100 degrees C), and aluminum concentrations (0.1-1 M) on the crystallization and transformation of these aluminum (oxy)hydroxides. Detailed structural and morphological characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) spectrometry revealed that these processes depend largely on the reaction temperature and the Al/OH- ratio. When 1 = 2.5 precipitation ceases unless the Al concentration is higher than 1 M. We identified pseudoboehmite, bayerite, and Gibbsite as intermediate phases to bayerite, Gibbsite and boehmite, respectively, all of which transform via dissolution-reprecipitation. Gibbsite transforms to boehmite in both acidic and weak caustic environments at temperatures above 80 degrees C. However, a "bar-shaped" Gibbsite morphology dominates in highly caustic environments (3 M NaOH). The findings enable a robust basis for the selection of various solid phases by tuning the reaction conditions
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crystallization of aluminium hydroxide from the reactive naal oh 4 nahco3 solution experiment and modeling
Chemical Engineering Science, 2010Co-Authors: Yifei Zhang, Chao Yang, Libin Chen, Yi ZhangAbstract:The crystallization kinetics of aluminium hydroxide from the sodium aluminate solution reacted with sodium bicarbonate were systematically investigated in a steady-state MSMPR (mixed-suspension mixed-product removal) crystallizer for the first time, and the expressions of the nucleation rate, growth rate and the agglomeration kernel of aluminium hydroxide were successfully regressed. The aluminium hydroxide particles precipitated from the reactive system are identified as Gibbsite by XRD and SEM examinations. The volume growth rate order of Gibbsite with respect to the relative supersaturation of the solution is above the linear growth rate order, and the spiral growth mechanism for the growth of the basal face of Gibbsite in the reactive system was further identified by the growth rate, morphology analysis as well as the calculated surface entropy factor. The secondary nucleation rate of Gibbsite from the reactive system is three to four orders of magnitude larger than that from seeded process reported in the only available literature reference. The agglomeration kernel of Gibbsite in the reactive system increases linearly with growth rate and residence time, and the positive order about 0.55 of magma density is thoroughly different from the negative order of magma density for Gibbsite agglomeration in seeded process presented in the literature.
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adjustment on Gibbsite and boehmite co precipitation from supersaturated sodium aluminate solutions
Transactions of Nonferrous Metals Society of China, 2010Co-Authors: Zhi Wang, Liu Yang, Juan Zhang, Zhancheng Guo, Yi ZhangAbstract:Gibbsite is the usual precipitation product from alumina refineries with either Bayer or sintering process. However, the advantage of boehmite precipitation over Gibbsite precipitation is the significant energy saving in the subsequent calcination step. The current investigation takes a pragmatic approach to measure precipitation ratios, determine product phase, morphology and particle size distribution, and assess the impacts and adjustment capability of main parameters such as seed, temperature, ethanol medium, and supersaturation on the precipitation kinetics and alumina hydrate type during co-precipitation process. The results clarify that Gibbsite and boehmite both can be precipitated from supersaturated sodium aluminate solutions simultaneously, and the competitive formation between Al(OH)3 and γ-AlOOH determines the main precipitate phases from pregnant liquor. Boehmite seeds, high temperature and ethanol addition can promote the boehmite precipitation and improve the mass fraction of boehmite in products. Co-precipitation changes the multimodal distribution of seeds to a normal and well distribution of products, and the particle size is more than several times that of seeds.