A theoretical study of Cs(I) adsorption on kaolinite basal surfaces

Chen, Zhongcun; Zhao, Yaolin; Tong, Dayin; Nie, Shaowei; Wang, Yuqi; Nie, Xiaomeng; Jia, Ziqi

doi:10.1016/j.chemphys.2021.111380

Cited by 4 publications

(5 citation statements)

References 51 publications

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“…The KLT aluminol surface is strongly hydrophilic compared with the siloxane surface. Due to the existence of hydrogen bonds, water molecules could occupy most adsorption sites and consequently suppress the direct bonding between cesium and the aluminol surface . This may agree with no Cs adsorption on KLT observed in the present study.…”

Section: Resultssupporting

confidence: 89%

“…Due to the existence of hydrogen bonds, water molecules could occupy most adsorption sites and consequently suppress the direct bonding between cesium and the aluminol surface. 24 This may agree with no Cs adsorption on KLT observed in the present study. A similar phenomenon was also observed by Chen et al 24 with NMR.…”

Section: Sr/cs Sorption To Eps Clays and Theirsupporting

confidence: 92%

“…24 This may agree with no Cs adsorption on KLT observed in the present study. A similar phenomenon was also observed by Chen et al 24 with NMR. On the other hand, there are a wide variety of isomorphous homomorphic substitutions in the MMT lattice, forming a negative charge between the layers, 25 but KLT did not.…”

Section: Sr/cs Sorption To Eps Clays and Theirsupporting

confidence: 92%

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Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

Zhang

Larson

Ballard

et al. 2023

ACS Earth Space Chem.

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The modification of clay minerals by exopolysaccharides (EPS) may significantly increase their adsorption capacity for heavy metals. This study focused on the adsorption of EPS (produced by Rhizobium tropici)-modified montmorillonite (MMT) and kaolinite (KLT) for Cs and Sr and the influence of external factors (pH, sulfate, and phosphate). The characterization of the composites was carried out using X-ray diffraction (XRD), Fourier transform infrared (FTIR), atomic force microscopy (AFM), and scanning electron microscopy/energy-dispersive X-ray analysis. With EPS modification, the adsorption capacity of MMT for Cs and Sr reached 256 and 90.9 mg/g, respectively, which were significantly improved by 53.8 and 54.5% compared to MMT alone, respectively. The adsorption capacity of KLT for Sr improved by 10.7%. KLT did not adsorb Cs either before or after EPS modification. The adsorption isotherms for Sr on MMT, EPS-MMT, KLT, and EPS-KLT as well as Cs on MMT and EPS-MMT were better described with the Freundlich adsorption models, indicating a heterogeneous layered adsorption process. XRD, FTIR, and AFM analysis confirmed the interlayer reaction of Sr/Cs with EPS-MMT. The Sr amounts adsorbed on EPS-MMT composites increased significantly with increasing pH, while the pH influence was not obvious on Cs adsorption but still slightly increased at pH 7 and then dropped at pH 9. In the presence of 50 and 500 mg/L sulfate, the Sr amount absorbed decreased by 12.5, and 29.3%, respectively. On the contrary, there was a significant increase in Cs adsorption by 12.2 and 33.9%, respectively. In the presence of phosphate, a significant increase (64.5%) was observed for Cs adsorption under 50 mg/L phosphate loading, but 500 mg/L phosphate inhibited (65.8%) the adsorption. In contrast, there was no significant change of Sr adsorption under different phosphate concentrations. The current study would provide a new insight for the application of biopolymers in remediation of Sr- and Cs-contaminated areas.

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Section: Resultssupporting

confidence: 89%

Section: Sr/cs Sorption To Eps Clays and Theirsupporting

confidence: 92%

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Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

Zhang

Larson

Ballard

et al. 2023

ACS Earth Space Chem.

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“…Computational approaches to the analysis of Cs adsorption on clay minerals have mainly been carried out using molecular dynamics (MD) simulations − and ab initio calculations. − The former directly simulates the dynamical behavior of Cs in water–clay systems, adsorption at edge sites, and exchange between inter- and intralayer spaces. Improved computational performance and highly accurate potential functions have made MD simulations involving many clay layers possible.…”

Section: Introductionmentioning

confidence: 99%

New Approach To Understanding the Experimental ¹³³Cs NMR Chemical Shift of Clay Minerals via Machine Learning and DFT-GIPAW Calculations

et al. 2023

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Structural determination of adsorbed atoms on layered structures such as clay minerals is a complex subject. Radioactive cesium (Cs) is an important element for environmental conservation, so it is vital to understand its adsorption structure on clay. The nuclear magnetic resonance (NMR) parameters of 133 Cs, which can be determined from solid-state NMR experiments, are sensitive to the local neighboring structures of adsorbed Cs. However, determining the Cs positions from NMR data alone is difficult. This paper describes an approach for identifying the expected atomic positions on clay minerals by combining machine learning (ML) with experimentally observed chemical shifts. A linear ridge regression model for ML is constructed from the smooth overlap of atomic position descriptor and gauge-including projector augmented wave (GIPAW) ab initio data. The constructed ML model predicts the GIPAW data to within a 3 ppm root-mean-squared error. At this stage, the 133 Cs chemical shifts can be instantaneously calculated from the Cs positions on any clay layers using ML. The inverse analysis, which derives the atomic positions from experimentally observed chemical shifts, is developed from the ML model. The input data for the inverse analysis are the layer structure and the experimentally observed chemical shifts. The Cs positions for the targeted chemical shifts are then output. Inverse analysis is applied to montmorillonite, and the resultant Cs positions are found to be consistent with previous results (Ohkubo, T.; et al. J. Phys. Chem. A 2018, 122, 9326−9337). The Cs positions on saponite clay are also clarified from experimentally observed chemical shifts and inverse analysis.

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“…Consequently, when subjected to external forces, kaolinite is more likely to split in a direction parallel to the layer and break into two different types of surfaces with different properties, i.e., base surfaces and edge surfaces. So far, to reduce research challenges that are complex for this topic, theoretical − and experimental studies − need to be continued on the ideal kaolinite structure without any lattice defects. Yet, the structure of the actual kaolinite crystal in the natural surrounding is different from that of the ideal kaolinite crystal due to the replacement of the aluminum and silicon ions by the lower positive valence ions or the formation of defects, which also leads to changes in the electrical properties of the crystal surfaces. , As part of the scientific research process, we need to understand how the structures and characteristics differ between the ideal and actual kaolinite crystal.…”

Section: Introductionmentioning

confidence: 99%

DFT Study on the Adsorption of Monomeric Hydroxyl Aluminum on Fe(II)/Mg Replacement Kaolinite (001) Surfaces

et al. 2022

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In the natural environment, Al and Si in the kaolinite crystal structure are likely to form lattice defects or be replaced by low-valence positive ions so that the base surfaces have permanent negatively charged sites. It is therefore very important to investigate the adsorption process and adsorption mechanism of adsorbates on the replaced surfaces. In this paper, two types of surface models formed by replacing Al atoms in the alumina octahedron of kaolinite (001) surface with Fe(II) and Mg were selected as the adsorption surfaces, these being the kaolinite Fe(II)Al-(001) and MgAl-(001) surfaces, respectively. Then, we used density functional theory (DFT) to simulate the adsorption of three monomeric hydroxy aluminum models (i.e., Al(OH)2 +, Al(OH)3, and Al(OH)4 –) on the two replaced surfaces. Results show that, when compared to the adsorption on the ideal kaolinite (001) surface, the adsorption energies of the three adsorbates adsorbed on the replaced surfaces are lower and the adsorption is more stable. When the three adsorbates are adsorbed on the kaolinite Fe(II)Al-(001) surface, adsorption stability increases with the number of hydroxyl groups, and hydrogen bonding and electrostatic adsorption play a major role. Conversely, when they were adsorbed on the kaolinite MgAl-(001) surface, the stability of the adsorption deteriorated as the number of hydroxyl groups increased. Moreover, the decisive roles are the interaction between the aluminum atoms in the adsorbates and the oxygen atoms on the replaced surface and the electrostatic adsorption.

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A theoretical study of Cs(I) adsorption on kaolinite basal surfaces

Cited by 4 publications

References 51 publications

Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

New Approach To Understanding the Experimental ¹³³Cs NMR Chemical Shift of Clay Minerals via Machine Learning and DFT-GIPAW Calculations

DFT Study on the Adsorption of Monomeric Hydroxyl Aluminum on Fe(II)/Mg Replacement Kaolinite (001) Surfaces

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A theoretical study of Cs(I) adsorption on kaolinite basal surfaces

Cited by 4 publications

References 51 publications

Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

New Approach To Understanding the Experimental 133Cs NMR Chemical Shift of Clay Minerals via Machine Learning and DFT-GIPAW Calculations

DFT Study on the Adsorption of Monomeric Hydroxyl Aluminum on Fe(II)/Mg Replacement Kaolinite (001) Surfaces

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Product

Resources

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New Approach To Understanding the Experimental ¹³³Cs NMR Chemical Shift of Clay Minerals via Machine Learning and DFT-GIPAW Calculations