Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 767, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.144973
Keywords
Geopolymer; Zeolite; Hydrothermal transformation; Hazardous elements adsorption
Categories
Funding
- National Natural Science Foundation of China (NSFC) [52072090, 51872063, 51832002]
- Natural Science Foundation of Heilongjiang Province [YQ2019E002]
- Heilongjiang Touyan Innovation Team Program
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This study demonstrates a facile method to prepare bulk zeolites with tunable phase compositions and microstructures by combining hydrothermal treatment and geopolymer precursor technique. By systematically investigating the effects of hydrothermal conditions, the optimal hydrothermal procedure for specific phase compositions is determined. The resulting zeolites show promising adsorption performance for hazardous elements, with mechanisms of chemisorption and ion exchanges elucidated.
This paper reports a facile route to prepare bulk zeolites with tunable phase compositions and microstructures by combining hydrothermal treatment and geopolymer precursor technique. Amorphous Na-based geopolymer (NaGP) is transformed into crystalline analcime following hydrothermal treatments. By systematically investigating the effects of hydrothermal conditions on the phase compositions and microstructures of the products, the optimal hydrothermal procedure is screened as treating NaGP in 1 M NaOH solution at 160 degrees C for 6 h. Further more, we achieve control over phase compositions of the resulting bulk zeolites by tailoring the initial Na/K ratio of geopolymer precursors. For instance, treating the geopolymer precursor with a Na/K ratio of 9: 1 under the optimal hydrothermal procedure leads to the formation of zeolite consisting of analcime and zeolite-P. The as-prepared adsorbents exhibit outstanding adsorption performance for the hazardous elements, among which analcime-zeolite-P shows an adsorption efficiency of 93.3% for Cs+, and NaGP exhibits an adsorption efficiency of 99.6% for Sr2+. Moreover, we reveal the mechanisms underlying the adsorption of Cs+ and Sr2+ in the adsorbents to be chemisorption. Meanwhile, ion exchanges also occur in NaGP and analcime-zeolite-P during Cs+ adsorption. These results render geopolymers and their derived bulk zeolites promising for hazardous elements adsorption. (C) 2021 Elsevier B.V. All rights reserved.
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