Safe trapping of cesium into doping-enhanced pollucite structure by geopolymer precursor technique

He, Peigang; Wang, Ruifei; Fu, Shuai; Wang, Meirong; Cai, Delong; Ma, Guoru; Wang, Meng; Yuan, Jingkun; Yang, Zhihua; Duan, Xiaoming; Wang, Yujin; Jia, Dechang; Zhou, Yu

doi:10.1016/j.jhazmat.2019.01.013

Cited by 50 publications

(13 citation statements)

References 34 publications

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“…Similar to zeolite structure, cations (eg, Li + , Na + , K + , and Cs + ) exist as counterions to balance the negative charges of [AlO 4 ] − in its framework. Such feature enables a flexible and designable control over the type and ratio of contained cations by employing different alkali‐activated solutions and/or regulating ion‐exchange processes, therefore, providing a convenient way to trap waste elements into the cage‐like structures by physical encapsulation. One can further convert the absorbed waste elements into the components of stable ceramic phase and, therefore, protecting them from leaching by strong chemical bonding.…”

Section: Introductionmentioning

confidence: 99%

Immobilization behavior of Sr in geopolymer and its ceramic product

Lou

Jia

et al. 2019

J Am Ceram Soc

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To date, geopolymer has emerged as a promising and inexpensive precursor with potential application in trapping hazardous elements via physical encapsulation or chemical bonding. In this work, different high‐temperature products derived from Sr‐contained geopolymer precursors were prepared. Different to conventional hazardous elements that immobilized in the geopolymer precursor, which show decreasing leaching rates after high‐temperature treatments, leaching rates of Sr in the resulting high‐temperature products first increase and then decrease with the increasing heating temperature. Herein, we first shed light on the underlying reasons of such temperature‐dependent leaching behaviors by investigating effects of heating temperature on the phase composition, microstructure, and immobilization mechanism. Moreover, a novel immobilization strategy has been proposed based on the blocking effect of formed nepheline structures at 1200°C. Using this strategy, the leaching rate of Sr reduced to 5.82 × 10−7g cm−2 d−1 in the deionized water.

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Section: Introductionmentioning

confidence: 99%

Immobilization behavior of Sr in geopolymer and its ceramic product

Lou

Jia

et al. 2019

J Am Ceram Soc

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“…Therefore, the Cl‐NEB method was used to calculate the energy barriers of the two migration modes at 0 K. The calculation results are shown in Figure 11. It has been pointed out that the size of the six‐oxygen channel is 2.8 Å, whereas the diameter of Cs + is about 3.34 Å 1 . The calculated energy barrier of the six‐oxygen ring channel is as high as 2.50 eV, indicating that the diffusion of Cs + through that channel is extremely difficult.…”

Section: Resultsmentioning

confidence: 99%

“…Due to the urgent need for global climate change mitigation, nuclear power with less greenhouse gas emissions has emerged as a satisfactory alternative to the traditional fossil fuel‐based units 1 . However, radioactive pollution would lead to hazardous consequences for humans and the environment, such as the Fukushima nuclear accident in Japan on March 11, 2011 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Immobilizing radionuclides into glass/ceramics has been widely accepted as a suitable method to dispose of nuclear waste 3,4 . Pollucite is a naturally occurring mineral consisting of disordered corner‐sharing (Al, SiO 4 )‐tetrahedra and charge‐balanced Cs + 1 . Due to the high content of Cs (up to 47% Cs by weight), it has been considered as a candidate host matrix for the immobilization of radioactive Cs.…”

Section: Introductionmentioning

confidence: 99%

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Insights into the leaching behavior of pollucite glass–ceramics at the initial stage

Yang

Zhao

et al. 2022

J Am Ceram Soc.

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Pollucite has been proposed as an ideal candidate material for addressing the critical challenge of the safe trapping of the 137Cs radionuclide. However, its detailed corrosion mechanism remains elusive. In this work, we performed reactive and ab initio molecular simulations to explore the leaching behavior of Cs+ from pollucite glass–ceramics at the initial stage. The nonbridging oxygen ions on the surface are protonated at first, followed by the release of Cs+ associated with these oxygen ions. For the glass phase, the inner Cs+ could leach out due to the interaction with water molecules, whereas only the Cs+ present at the surface leach out for pollucite, confirming its remarkable chemical stability. The hydrolysis of Si/Al–O bonds in pollucite is thermodynamically unfavorable, and Al–O bonds are the weak spots. Moreover, the migration barriers of Cs+ in pollucite were calculated by the climbing image nudged elastic band method, and the high barriers reveal that pollucite immobilizes Cs+ stably. This study paves the way for predicting the long‐term safety of a nuclear waste immobilization repository.

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“…He et al [ 123 ] found pollucite can be formed from Cs-based geopolymers synthesized from synthetic metakaolin at a lower temperature (800~1000 °C). Furthermore, He et al [ 67 ] obtained pollucite with excellent S/S performance of Cs from geopolymer calcined at a low temperature (<1000 °C) via alkali metal ion doping and optimizing the Na/Cs ratio. Chen et al [ 124 ] proposed a hybrid hydrothermal-sintering process including a 200 °C hydrothermal process and an additional 1200 °C sintering process, which can effectively lower the amount of Cs lost to volatilization.…”

Section: Geopolymer-based S/s Processmentioning

confidence: 99%

Application of Geopolymer in Stabilization/Solidification of Hazardous Pollutants: A Review

et al. 2022

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Geopolymers, as a kind of inorganic polymer, possess excellent properties and have been broadly studied for the stabilization/solidification (S/S) of hazardous pollutants. Even though many reviews about geopolymers have been published, the summary of geopolymer-based S/S for various contaminants has not been well conducted. Therefore, the S/S of hazardous pollutants using geopolymers are comprehensively summarized in this review. Geopolymer-based S/S of typical cations, including Pb, Zn, Cd, Cs, Cu, Sr, Ni, etc., were involved and elucidated. The S/S mechanisms for cationic heavy metals were concluded, mainly including physical encapsulation, sorption, precipitation, and bonding with a silicate structure. In addition, compared to cationic ions, geopolymers have a poor immobilization ability on anions due to the repulsive effect between them, presenting a high leaching percentage. However, some anions, such as Se or As oxyanions, have been proved to exist in geopolymers through electrostatic interaction, which provides a direction to enhance the geopolymer-based S/S for anions. Besides, few reports about geopolymer-based S/S of organic pollutants have been published. Furthermore, the adsorbents of geopolymer-based composites designed and studied for the removal of hazardous pollutants from aqueous conditions are also briefly discussed. On the whole, this review will offer insights into geopolymer-based S/S technology. Furthermore, the challenges to geopolymer-based S/S technology outlined in this work are expected to be of direct relevance to the focus of future research.

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Safe trapping of cesium into doping-enhanced pollucite structure by geopolymer precursor technique

Cited by 50 publications

References 34 publications

Immobilization behavior of Sr in geopolymer and its ceramic product

Immobilization behavior of Sr in geopolymer and its ceramic product

Insights into the leaching behavior of pollucite glass–ceramics at the initial stage

Application of Geopolymer in Stabilization/Solidification of Hazardous Pollutants: A Review

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