Synthesis of mesoporous geopolymers containing zeolite phases by a hydrothermal treatment

Lee, NK; Khalid, Hammad R.; Lee, Haeng‐Ki

doi:10.1016/j.micromeso.2016.04.016

Cited by 111 publications

(53 citation statements)

References 36 publications

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“…According to literature, porosity of alkali activated materials decreases by increasing alkalinity of the activator solution [33,34]. This porosity reduction reduces permeation flux through the membrane support.…”

Section: Pv Test Resultsmentioning

confidence: 97%

Ceramic membrane synthesis based on alkali activated blast furnace slag for separation of water from ethanol

Azarshab

Mohammadi

Maghsoodloorad

et al. 2016

Ceramics International

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Section: Pv Test Resultsmentioning

confidence: 97%

Ceramic membrane synthesis based on alkali activated blast furnace slag for separation of water from ethanol

Azarshab

Mohammadi

Maghsoodloorad

et al. 2016

Ceramics International

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“…The strength of fly ash-based geopolymers varies according to the curing conditions and precursor/activator composition. While the strength of those cured at an elevated temperature and ambient pressure can be as high as 40 MPa at 28 days [21,22], and have the potential to develop further at later ages [23], the geopolymer specimens, in which a significant amount of aluminosilicate gel is transformed into crystalline zeolite at an elevated pressure, show limited strength (i.e., as low as 2 MPa at 28 days [24]). While the strength decline in geopolymers via crystallization is a generally acknowledged deterioration phenomenon of geopolymers, its nanostructural characterization remains limited.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

et al. 2018

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The present study investigated geopolymerization in alkali-activated fly ash under elevated pressure conditions. The fly ash was activated using either sodium hydroxide or a combination of sodium silicate solution and sodium hydroxide, and was cured at 120 • C at a pressure of 0.22 MPa for the first 24 h. The pressure-induced evolution of the binder gel in the alkali-activated fly ash was investigated by employing synchrotron X-ray diffraction and solid-state 29 Si and 27 Al MAS NMR spectroscopy. The results showed that the reactivity of the raw fly ash and the growth of the zeolite crystals were significantly enhanced in the samples activated with sodium hydroxide. In contrast, the effects of the elevated pressure conditions were found to be less apparent in the samples activated with the sodium silicate solution. These results may have important implications for the binder design of geopolymers, since the crystallization of geopolymers relates highly to its long-term properties and functionality.

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“…Literature data [7][8][9] show that the zeolite structures can be synthesized not only in metakaolinite-based material. Actually, zeolites can be synthesized under hydrothermal conditions by heating many other aluminosilicate raw materials such as fly ash [10] or volcanic glasses in the presence of alkaline solutions [11][12].…”

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confidence: 99%

“…It is possible to obtain chabazite and sodalite in fly ashbased geopolymers (as monolith) and also zeolite X and zeolite 4A in geopolymers activated with weak alkaline solution and zeolite Na-P1 with a strong activator [7]. Interestingly, the disposal of secondary waste materials such as fly ash (a by-product of coal combustion) has become both an economic and an environmental issue.…”

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confidence: 99%

“…In contrast to the procedures described in the related literature [7,9], the proposed process was conducted at relatively low temperature and autogenous pressure as well as without thermal pretreatment. Since the composition of fly ash is not suitable for this type of synthesis (too high Si/Al molar ratio), it was assumed that the zeolite phase, such as zeolite A, zeolite X, or hydroxysodalite, will be obtained by the addition of an aluminum source.…”

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confidence: 99%

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Synthesis of the Sodalite by Geopolymerization Process Using Coal Fly Ash

Król¹,

Rożek²,

Mozgawa³

2017

Pol. J. Environ. Stud.

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IntroductionGeopolymers, also called inorganic polymers, are classified as synthetic aluminosilicate materials characterized by many interesting properties. This group of materials has gained a lot of attention in the past 10 years (measured by increasing number of publications) and raised high expectations concerning their applicability. Geopolymers are usually hard, mechanically resistant materials, therefore many attempts to substitute Portland cement in the construction industry have been taken [1]. Despite the huge number of publications devoted to this family and hundreds of new examples of these materials, researching them is still pioneering [2]. Attempts to systematize their structures and properties are just beginning to appear.Geopolymers are considered as zeolite precursors, thus zeolites are often detected in geopolymer gels. Activation of metakaolinite with sodium silicate and sodium hydroxide solutions at various temperatures (20-100ºC) can lead to the geopolymer-zeolite hybrid materials containing zeolite A, sodalite, and zeolite Y [3]. During hydrothermal treatment at low temperature, depending on the synthesis conditions, metakaolin-based geopolymeric gel transforms into zeolite ZSM-20, zeolite Na-P1, faujasite, sodalite, and analcime [4]. Metakaolin-based geopolymeric gel was also used for hydrothermal preparation of a faujasite zeolite membrane for alcohol/water separation [5]. On the other hand, non-hydrothermal preparation of Na-A zeolite membranes from chemosynthetic Al 2 O 3 -SiO 2 powder and sodium silicate solution by the geopolymer gel thermal conversion at 60ºC is possible [6].Pol. J. Environ. Stud. Vol. 26, No. 6 (2017), 2611-2617 AbstractThis study investigated the influence of alkali activation process conditions on the amount and types of zeolites in the resultant geopolymers. The products were formed during the alkaline activation of coal fly ash with the use of aluminium and sodium hydroxide solution. Geopolymers were cured at 80ºC for 24 h. The effects of reaction systems' constitution (expressed as SiO 2 /Al 2 O 3 and Al 2 O 3 /Na 2 O molar ratios) on the phase composition and structure of obtained products were determined. The results indicated that the products obtained from such hydrothermal treatment demonstrated the characteristics of zeolite-like materials -sodalite. By using the appropriate composition of the initial solution (sufficiently high concentration of NaOH and aluminum carrier), it is possible to synthesize the sodalite phase efficiently in an amorphous matrix.

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Synthesis of mesoporous geopolymers containing zeolite phases by a hydrothermal treatment

Cited by 111 publications

References 36 publications

Ceramic membrane synthesis based on alkali activated blast furnace slag for separation of water from ethanol

Ceramic membrane synthesis based on alkali activated blast furnace slag for separation of water from ethanol

Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

Synthesis of the Sodalite by Geopolymerization Process Using Coal Fly Ash

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