Microwave-Assisted Hydrothermal Synthesis of Pure-Phase Sodalite (>99 wt.%) in Suspension: Methodology Design and Verification

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27350%2F24%3A10253849" target="_blank" >RIV/61989100:27350/24:10253849 - isvavai.cz</a>

Result on the web

<a href="https://www.webofscience.com/wos/woscc/full-record/WOS:001141400500001" target="_blank" >https://www.webofscience.com/wos/woscc/full-record/WOS:001141400500001</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/ma17010269" target="_blank" >10.3390/ma17010269</a>

Result language

angličtina

Original language name

Microwave-Assisted Hydrothermal Synthesis of Pure-Phase Sodalite (>99 wt.%) in Suspension: Methodology Design and Verification

Original language description

Despite numerous studies focused on the hydrothermal (HT) synthesis of fly ash zeolites (FAZs), this method still has many limitations, the main of which is the low yield of zeolites. Hydrothermally synthesized zeolites are typically multiphase and exhibit low purity, which limits their applicability. Pure-phase zeolites have been primarily prepared from filtrates after alkaline mineralization of fly ashes, not directly in suspension. In addition, the published methodologies have not been tested in a wider set of samples, and thus their reproducibility is not confirmed. The aim of the study is to propose a reproducible methodology that overcomes the mentioned limitations. The influence of the Si/Al ratio (1.3:1-1:2), the type and concentration of the activator (2/4 M NaOH/KOH/LiOH), the reagent (30% LiCl), the duration (24-168 h), and the temperature (50-180 degrees C) of the synthesis phases were studied. The sequence of the synthesis phases was also optimized, depending on the type of heat transfer. The fly ashes were analyzed by wavelength-dispersive X-ray fluorescence (WD XRF), flame atomic absorption spectrometry (F-AAS), and X-ray diffraction (XRD). The energy intensity of the synthesis was reduced through the application of unique microwave digestion technology. Both microwave and combined (microwave and convection) syntheses were conducted. FAZs were identified and quantified by XRD analysis. This study presents a three-stage (TS) hydrothermal synthesis of pure-phase sodalite in suspension. Sodalite (&gt;99 wt.%) was prepared from nine fly ashes under the following conditions: I. microwave phase: 120 degrees C, 150 min, solid-to-liquid ratio (S/L) 1:5, Si/Al ratio 1:1.5, and 4 M NaOH; II. convection phase: 120 degrees C, 24 h, S/L 1:40, and the addition of 30 mL of 30% LiCl; and III. crystallization: 70 degrees C for 24 h. The formation of rhombododecahedral sodalite crystals was confirmed by scanning electron microscope (SEM) images.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20703 - Mining and mineral processing

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Materials

ISSN

1996-1944

e-ISSN

1996-1944

Volume of the periodical

17

Issue of the periodical within the volume

1

Country of publishing house

CH - SWITZERLAND

Number of pages

23

Pages from-to

1-23

UT code for WoS article

001141400500001

EID of the result in the Scopus database

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