Structure model of Al,K-substituted tobermorite and structural changes upon heating

Organova, N. I.; Копорулина, Е. В.; Иванова, А. Г.; Trubkin, N. V.; Zadov, Alexander E.; Khomyakov, A. P.; Marcille, I. M.; Чуканов, Н. В.; Shmakov, A. N.

doi:10.1134/1.1523539

Cited by 8 publications

(9 citation statements)

References 8 publications

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“…In this study, tobermorite was stable from 190 • C to 250 • C, grossular was stable from 160 • C to 250 • C, and α-C 2 SH appeared only at 190 • C. These results are consistent with the results obtained in the studies by Ríos et al and Meller et al [15,16]. There was no evidence that Al-substituted tobermorite was formed; however, it is possible that the Al substitution for Si in tobermorite increased its stability [33,34]. Besides, the generation of α-C 2 SH and tobermorite was greatly affected by the initial Ca/Si ratio in the starting material (Table 1).…”

Section: Crystalsupporting

confidence: 88%

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

2019

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To elucidate the physicochemical properties of the artificial silicate composite material, K-feldspar and lime were reacted in mild hydrothermal conditions (different reaction temperatures and various K-feldspar/lime ratios). Formed phases were investigated using various techniques, such as X-ray powder diffraction, the Rietveld method, scanning electron microscopy (SEM), and inductively coupled plasma-optical emission spectrometry. The analysis revealed that tobermorite, grossular (hydrogarnet), alpha-dicalcium silicate hydrate (α-C2SH), amorphous calcium silicate hydrate, potassium carbonate, bütschliite, calcite, and calcium hydroxide formed with various conditions. Both the temperature and the Ca/Si molar ratio in the starting material greatly affected the formation of phases, especially the generation of tobermorite and α-C2SH. The substitution of H4O4 ↔ SiO4 proceeded with the increase of the Ca/Si molar ratio rather than the reaction temperature and the reaction time. More hydrogen was incorporated in hydrogarnet through the substitution of H4O4 ↔ SiO4 with the increase of the Ca/Si molar ratio in the starting material. Due to the properties of tobermorite as a cation exchanger and its potential applications in hazardous waste disposal, experimental parameters should be optimized to obtain better performance of the artificial silicate composite material from K-feldspar and lime hydrothermal reaction. The dissolution mechanism of K-feldspar was also discussed.

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Section: Crystalsupporting

confidence: 88%

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

2019

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“…In this work, various x Na changed the bulk Ca/Si ratio as well as the species of metal cations, and consequently, spheroidal, laminar, needle, and fibroid tobermorite were acquired. Additionally, tobermorite was proved to be Al‐substituted from EDS results (Table ,a–e,g), which is a phenomenon that was also reported elsewhere . Small amount of Na and K found in tobermorite was related to the electric balance by (Na + , K + ) + Al 3+ = Si 4+ .…”

Section: Resultssupporting

confidence: 79%

“…Additionally, tobermorite was proved to be Al-substituted from EDS results ( Table 2,a-e,g), which is a phenomenon that was also reported elsewhere. 22,23 Small amount of Na and K found in tobermorite was related to the electric balance 24,25 by (Na + , K + ) + Al 3+ = Si 4+ . Though nepheline hydrate was identified by XRD analyses at x Na of 0.4-0.8, its typical crystal was found at x Na = 0.6-0.8.…”

Section: Morphologymentioning

confidence: 99%

Hydrothermal reaction of K‐feldspar powder in NaOHCa (OH)₂ mixed medium

Liu

Gao

2019

Asia-Pacific J Chem Eng

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The hydrothermal reactions between K‐feldspar powder and NaOHCa (OH)2 mixed alkaline medium at 240°C were investigated. The effects of Na ratio (xNa, Na2O/(Na2O + CaO) in mole) on the phase and composition change in solid products were explored in detail. Results showed that increase in xNa led to the orderly formation of compounds following the sequence of CaOSiO2H2O → Na2OCaOSiO2H2O → Na2OAl2O3SiO2H2O, and K+ was accessible into solution after reaction. The new products after reaction was tobermorite, pectorite, nepheline hydrate, analcime, and hydroxycancrinite, depending on different xNa. The hydrothermal reaction was deduced to be a coupled dissolution and reprecipitation process, which was governed by the chemical equilibrium with the change in solution chemistry.

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“…Both potassium carbonate and bütschliite originated from potassium hydroxide, which is one of the primary products of the hydrothermal reaction. The remaining released K was from water‐insoluble product, namely, the difference between the results obtained with 0.5 mol L −1 HCl and those obtained with deionized water (Table S1) may be due to the structure of tobermorite because EDS data suggested that tobermorite contained some K atoms in our previous study, and several K ions entered into tobermorite to maintain electrical neutrality for the Al‐substituted tobermorite …”

Section: Resultsmentioning

confidence: 99%

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

2018

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An artificial silicate composite material prepared by the hydrothermal reaction of K‐feldspar and lime, showed excellent performance in remediating the soil. To elucidate the physicochemical properties of the artificial silicate composite material, K‐feldspar and lime were reacted in mild hydrothermal conditions (T=190 °C; P∼12.4 atm; t=0∼36 h). The hydrothermal product was systematically investigated using various techniques such as X‐ray powder diffraction (XRPD), scanning electron microscopy, and inductively coupled plasma‐optical emission spectrometry (ICP–OES). Quantitative evaluation of the extent of reaction by ICP–OES and XRPD methods enabled the analysis of hydrothermal evolution with prolonged time. The hydrothermal treatment of K‐feldspar with lime exhibits complex product phases, including leftover K‐feldspar, calcium hydroxide, calcite, grossular, tobermorite, alpha‐dicalcium silicate hydrate, potassium carbonate, bütschliite, and amorphous calcium silicate hydrate. The analysis of the reaction reveals that the K‐feldspar dissolution showed a clear transition, with the hydrothermal reaction beginning to slow down after 20 h. The slowdown of the K‐feldspar dissolution was essentially caused by different reaction kinetics and mechanisms before and after 20 h. The study yields vital and valuable insights into comprehending the chemistry and mineralogy of the artificial silicate composite material and producing a multielement reservoir from potassium‐rich rocks.

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Structure model of Al,K-substituted tobermorite and structural changes upon heating

Cited by 8 publications

References 8 publications

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Hydrothermal reaction of K‐feldspar powder in NaOHCa (OH)₂ mixed medium

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

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Structure model of Al,K-substituted tobermorite and structural changes upon heating

Cited by 8 publications

References 8 publications

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Hydrothermal reaction of K‐feldspar powder in NaOHCa (OH)2 mixed medium

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

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Hydrothermal reaction of K‐feldspar powder in NaOHCa (OH)₂ mixed medium