Concentration variation of aluminate ions during the seeded precipitation process of gibbsite from sodium aluminate solution

Li, Xiaobin; Wang, Danqin; Zhou, Qiusheng; Liu, Guihua; Peng, Zhihong

doi:10.1016/j.hydromet.2010.12.002

Cited by 24 publications

(13 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 a) [22] . The infrared spectrum of all Al(OH) 3 coated samples showed the disappearance of adsorption peaks of C–H at 2845 cm −1 and 2950 cm −1 after coating with Al(OH) 3 , confirming that oleylamine had been removed, and the appearance of three absorption peaks at 842 cm −1 and 1645 cm −1 and a broad band from 3000 to 3500 cm −1 , corresponding respectively to the Al–O stretching [23] , the deformation vibration of water, and O–H stretching mode ( Fig. S1 ).…”

Section: Resultsmentioning

confidence: 73%

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

et al. 2014

View full text Add to dashboard Cite

Magnetic nanoparticles (NPs) MnFe2O4 and Fe3O4 were stabilised by depositing an Al(OH)3 layer via a hydrolysis process. The particles displayed excellent colloidal stability in water and a high affinity to [18F]-fluoride and bisphosphonate groups. A high radiolabeling efficiency, 97% for 18F-fluoride and 100% for 64Cu-bisphosphonate conjugate, was achieved by simply incubating NPs with radioactivity solution at room temperature for 5 min. The properties of particles were strongly dependant on the thickness and hardness of the Al(OH)3 layer which could in turn be controlled by the hydrolysis method. The application of these Al(OH)3 coated magnetic NPs in molecular imaging has been further explored. The results demonstrated that these NPs are potential candidates as dual modal probes for MR and PET. In vivo PET imaging showed a slow release of 18F from NPs, but no sign of efflux of 64Cu.

show abstract

Section: Resultsmentioning

confidence: 73%

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The peak at 880cm −1 is ascribed to the stretching vibration of [AlO 2 ] − , which indicates that Al(OH) 3 is stabilized in the initial CaAl-Cl-LDH or the final Co-adsorbed LDH under weak acidic conditions [ 19 ]. There are two wide absorption bands near the regions of 650−800 cm −1 and 3000−3750 cm −1 , which are generally ascribed to the amorphous phases [ 20 ]. Either of the bands obtained at 770 cm −1 or 534 cm −1 are related to the stretching and bending vibration of Al-OH groups caused by Co 2+ adsorption [ 18 ].…”

Section: Resultsmentioning

confidence: 99%

Crystalline/Amorphous Blend Identification from Cobalt Adsorption by Layered Double Hydroxides

et al. 2018

View full text Add to dashboard Cite

In this study, the adsorption behavior of CaAl-Cl layered double hydroxide (CaAl-Cl-LDH) with a controlled pH value (pH = 6) on Co(II) ions ([Co] = 8 mM) is investigated. The comprehensively accepted mechanism of cobalt adsorption on LDH is considered to be co-precipitation, and the final adsorbed products are normally crystalline Co-LDH. One unanticipated finding is that crystalline/amorphous blends are found in the X-ray diffraction (XRD) pattern of Co-adsorbed LDH. To shed light on the adsorption products and the mechanisms in the adsorption process of Co(II) in an aqueous solution by CaAl-Cl-LDH, a series of testing methods including Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), High-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP) are applied to clarify the interaction between cobalt and CaAl-Cl-LDH. According to the comprehensive analysis, the formation of the crystalline/amorphous blends corresponds to two adsorption mechanisms. The crystalline phases are identified as Co6Al2CO3(OH)16·4H2O, which is attributed to the co-precipitation process occurring in the interaction between Co(II) and CaAl-Cl-LDH. The formation of the amorphous phases is due to surface complexation on amorphous Al(OH)3 hydrolyzed from CaAl-Cl-LDH.

show abstract

“…For dissolution under acidic or neutral conditions, rates are intrinsically linked to solution-phase species; , therefore, it is likely that speciation is key in alkaline environments as well . The dominant species present in caustic Al mixtures is widely accepted to be the tetrahedrally coordinated aluminate ion, Al(OH) 4 – . , The formation of tetrahedrally coordinated dimeric species, such as Al 2 O(OH) 6 2– at [Al] > 1.0 M, has also been proposed on the basis of Raman, nuclear magnetic resonance (NMR), and conductivity measurements. − The structure of the dimer in terms of whether it is oxy-bridged versus hydroxy-bridged or instead existing as an unbridged ion–ion aggregate is still under debate. ,, Both the monomeric and polymeric Al species are proposed to be stabilized with labile alkali ions . At high concentrations, closely packed Na + Al(OH) 4 – ion pairs and solvent molecules are consistent with dielectric relaxometry studies in 8 M NaOH, but measurements were not sensitive to the other species .…”

Section: Introductionmentioning

confidence: 99%

In Situ ²⁷Al NMR Spectroscopy of Aluminate in Sodium Hydroxide Solutions above and below Saturation with Respect to Gibbsite

et al. 2018

View full text Add to dashboard Cite

Aluminum hydroxide (Al(OH), gibbsite) dissolution and precipitation processes in alkaline environments play a commanding role in aluminum refining and nuclear waste processing, yet mechanistic aspects underlying sluggish kinetics during crystallization have remained obscured due to a lack of in situ probes capable of isolating incipient ion pairs. At a molecular level Al is cycling between tetrahedral ( T ) coordination in solution to octahedral ( O) in the solid. We explored dissolution of Al(OH) that was used to produce variably saturated aluminate (Al(OH))-containing solutions under alkaline conditions (pH >13) with in situ Al magic angle spinning (MAS)-nuclear magnetic resonance (NMR) spectroscopy, and interrogated the results with ab initio molecular dynamics (AIMD) simulations complemented with chemical shift calculations. The collective results highlight the overall stability of the solvation structure for T Al in the Al(OH) oxyanion as a function of both temperature and Al concentration. The observed chemical shift did not change significantly even when the Al concentration in solution became supersaturated upon cooling and limited precipitation of the octahedral Al(OH) phase occurred. However, subtle changes in Al(OH) speciation correlated with the dissolution/precipitation reaction were found. AIMD-informed chemical shift calculations indicate that measurable perturbations should begin when the Al(OH)···Na distance is less than 6 Å, increasing dramatically at shorter distances, coinciding with appreciable changes to the electrostatic interaction and reorganization of the Al(OH) solvation shell. The integrated findings thus suggest that, under conditions incipient to and concurrent with gibbsite crystallization, nominally expected contact ion pairs are insignificant and instead medium-range (4-6 Å) solvent-separated Al(OH)···Na pairs predominate. Moreover, the fact that these medium-range interactions bear directly on resulting gibbsite characteristics was demonstrated by detailed microscopic and X-ray diffraction analysis and by progressive changes in the fwhm of the O resonance, as measured by in situ NMR. Sluggish gibbsite crystallization may arise from the activation energy associated with disrupting this robust medium-range ion pair interaction.

show abstract

Concentration variation of aluminate ions during the seeded precipitation process of gibbsite from sodium aluminate solution

Cited by 24 publications

References 19 publications

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

Crystalline/Amorphous Blend Identification from Cobalt Adsorption by Layered Double Hydroxides

In Situ ²⁷Al NMR Spectroscopy of Aluminate in Sodium Hydroxide Solutions above and below Saturation with Respect to Gibbsite

Contact Info

Product

Resources

About

Concentration variation of aluminate ions during the seeded precipitation process of gibbsite from sodium aluminate solution

Cited by 24 publications

References 19 publications

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging

Crystalline/Amorphous Blend Identification from Cobalt Adsorption by Layered Double Hydroxides

In Situ 27Al NMR Spectroscopy of Aluminate in Sodium Hydroxide Solutions above and below Saturation with Respect to Gibbsite

Contact Info

Product

Resources

About

In Situ ²⁷Al NMR Spectroscopy of Aluminate in Sodium Hydroxide Solutions above and below Saturation with Respect to Gibbsite