Exchange reactions in aluminosilicate solutions

Harris, Robin K.; Parkinson, John Everett; Samadi‐Maybodi, Abdolraouf; Smith, Warren J.

doi:10.1039/cc9960000593

Cited by 18 publications

(12 citation statements)

References 8 publications

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“…In contrast to spectra at long times after preparation shown in Fig. 3, this does not show any q 3 or q 4 signals. Thus the condensation or aggregation of species decreases with decreasing Si, Al and Na C concentrations.…”

Section: Resultscontrasting

confidence: 78%

“…The distribution of aluminosilicate species has been shown to change with ageing time. 3 To understand better the interactions between silicate and aluminosilicate species in the presence of different cation types, it is pertinent to study the evolution with time of the six solutions mentioned in the Experimental section. 27 Al NMR spectra were obtained as a function of time following the mixing of sodium aluminate and an aged HM(OH) 2 silicate solution with the composition Si, Al D Na and template equal to 0.014, 0.014 and 0.028 molar, respectively, i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Several aluminosilicate solutions were prepared by using alkali metal and TAA hydroxide solutions, such as NaOH, KOH, TMAOH, TEAOH, HMBTP(OH) 3 (I) and HM(OH) 2 (II), to provide the cation templates. The aluminosilicate solutions were made by adding the alkali metal or substituted ammonium hydroxide silicate solution to freshly prepared sodium aluminate solution to achieve an Si : Al ratio of 1.…”

Section: Methodsmentioning

confidence: 99%

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Aluminium‐27 NMR investigation of the influence of cation type on aluminosilicate solutions

Azizi

Harris

Samadi‐Maybodi

2002

Magnetic Reson in Chemistry

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The effects of tetraalkylammonium (TAA) and alkali metal cations on the equilibrium distribution of aluminosilicate oligomers in aqueous alkaline aluminosilicate solutions were investigated using 27 Al NMR spectra and their evolution with time. The results indicate that there are no differences in the initial equilibria involving solutions containing both TAA and alkali metal cations on the one hand and those containing alkali metal cations only. However, re-equilibration of the aluminosilicate species for TAA/Na aluminosilicates is slow (usually not detectable on the time-scale of the experiments), whereas when purely alkali metal cations are used, the spectra alter over a period of ∼1 h, such that resolution is degraded substantially. In the latter case, it is suggested that the anions aggregate into larger systems, although the solutions are still clear. 29 Si NMR evidence for slow equilibration of silicate and aluminosilicate solutions at higher concentrations is also discussed.

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Section: Resultscontrasting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Aluminium‐27 NMR investigation of the influence of cation type on aluminosilicate solutions

Azizi

Harris

Samadi‐Maybodi

2002

Magnetic Reson in Chemistry

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“…It should be noted that liquid-state 29 Si NMR may not detect aqueous aluminosilicates at the concentration and temperature used here. 26,43 These species have been detected by 27 Al NMR, [44][45][46][47] which is more sensitive than 29 Si NMR mainly due to the higher natural abundance of 27 Al nucleus.…”

Section: Aqueous Species During Geopolymerizationmentioning

confidence: 99%

Setting and nanostructural evolution of metakaolin geopolymer

et al. 2017

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The nanostructural evolution during formation of geopolymers and its correlation with setting have not been well understood. In this study, penetration resistance and ultrasonic wave reflection tests were conducted to measure setting, and solid‐state 27Al NMR and liquid‐state 29Si NMR were used to examine nanostructural changes in a metakaolin geopolymer as a function of time. Aluminum was released rapidly during the first 10 hour after mixing and immediately condensed with silicate species in solution to form larger sized aluminosilicate oligomers, which then condensed to form large structural units. Our evidence suggests these units form near metakaolin particle surface. Smaller sized silicate ions in the sol phase then attach to these units to form a gel with a more interconnected network structure. The initial stage of this attaching process was seen to be associated with set, which in this mixture occurred at 15 hour.

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“…1 that shows five separate bands, indicating the existence of at least five kinds of aluminosilicate species. In this figure, q 0 (AlO 5 4 − ) and q 1 (aluminosilicate species with one siloxane bridge) should be present at 80 ppm and 75 ppm, respectively [38][39][40]. However, the first band at the highest frequency appears at 80 ppm that is related to q 0 species and the second bond in the NMR spectrum illustrates the aluminosilicate species with one siloxane bridge (q 1 ).…”

Section: Resultsmentioning

confidence: 91%

27Al NMR study of the effect of aqueous and methanolic media on the distribution of tetraphenylammonium aluminosilicate species

Goudarzi

2015

J Struct Chem

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The effects of tetraphenylammonium (TPhA) on the equilibrium distribution of aluminosilicate oligomers in aqueous and methanolic alkaline aluminosilicate solutions are investigated using 27 Al NMR spectroscopy. Alkaline solutions containing both silicate and aluminate ions are of considerable research interest inter alia because of their involvement in the synthesis of zeolites. In the present work, we use 27 Al NMR to characterize alkaline aqueous and methanolic tetraphenylammonium (TPhA) aluminosilicate solutions with different Al/Si ratios. Tetraphenylammonium (TPhA) is used as a cation template and no alkalie metals are used for the preparation of aluminosilicate solutions. The distribution of aluminosilicate species is affected by the presence of the alcohol such as methanol and the method of mixing the silicate and aluminosilicate solutions. To understand the reaction between silicate and aluminate ions in this system, the evolutions of 27 Al NMR spectra with time are investigated.

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Exchange reactions in aluminosilicate solutions

Abstract: Aluminium-27 NMR spectra at 156.3 MHz for alkaline aqueous aluminosilicate solutions show that full equilibria between species is approached slowly at room temperature but that some exchange processes are rapid.

Cited by 18 publications

References 8 publications

Aluminium‐27 NMR investigation of the influence of cation type on aluminosilicate solutions

Aluminium‐27 NMR investigation of the influence of cation type on aluminosilicate solutions

Setting and nanostructural evolution of metakaolin geopolymer

27Al NMR study of the effect of aqueous and methanolic media on the distribution of tetraphenylammonium aluminosilicate species

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