Activated carbon/attapulgite composites for radon adsorption

Liu, Li; Deng, Xiangyuan; Liao, Yang; Xiao, Detao; Wang, Meng

doi:10.1016/j.matlet.2020.129177

Cited by 14 publications

(5 citation statements)

References 14 publications

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“…In contrast to energy-intensive ventilation and shielding methods, solid porous adsorbents, such as activated carbon (AC), zeolite, porous organic cages, and metal–organic frameworks (MOFs), − offer promising solutions for Rn removal. MOFs, in particular, are highly versatile materials with well-defined structures, uniform pore sizes, and tunability, making them suitable for gas separation and capture. − However, the rapid and precise discovery of a specific functional MOF, particularly for Rn capture, from the vast pool of millions of candidates remains a formidable challenge.…”

Section: Introductionmentioning

confidence: 99%

Water Unexpectedly Impacts Both Thermodynamics and Kinetics of Rn Removal in HKUST-1

Geng,

Mao,

et al. 2023

J. Phys. Chem. C

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Excessive radon (Rn) exposure remains a significant risk factor for lung cancer in the general population. Metal–organic frameworks (MOFs) have emerged as promising materials for Rn radiation protection due to their unique characteristics, including large surface areas and customizable porous structures. However, the presence of water molecules, both during the synthesis process and in humid air, has often been overlooked but can significantly impact the Rn adsorption performance of MOFs in practical applications. In this study, we conducted a comprehensive investigation into the influence of varying water contents on the Rn selectivity and Rn adsorption capacity of HKUST-1, a prospective candidate. Our findings revealed that the primary Rn capture site within HKUST-1 is a tetrahedral cage (SCage) with a diameter of approximately 5.4 Å, which is ideally suited for accommodating Rn. Interestingly, increasing water content enhances the Rn adsorption capacity and selectivity of HKUST-1, primarily due to thermodynamic advantages. However, fully coordinated water molecules can give rise to additional narrow pore apertures (∼3.7 Å), resulting in a high kinetic barrier (∼16.8 kcal/mol) that hampers Rn adsorption by SCage. Consequently, water molecules play a crucial role in regulating the delicate balance between thermodynamics and kinetics in Rn adsorption by modifying the pore aperture morphology of the adsorption site within HKUST-1. Our theoretical calculations predict the optimal range of water content in HKUST-1 for efficient Rn removal, spanning from 0 wt % (fully dehydrated) to 8 wt % (fully coordinated). These findings not only provide theoretical explanations and guidance for future experimental endeavors but also offer valuable insights and references into the role of water molecules in modulating gas separation within MOFs containing open metal sites under different humidity or activation levels.

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Section: Introductionmentioning

confidence: 99%

Water Unexpectedly Impacts Both Thermodynamics and Kinetics of Rn Removal in HKUST-1

Geng,

Mao,

et al. 2023

J. Phys. Chem. C

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“…The modified AC was applied to purify the simulated exhaust gas of acetone, and 1% KOH-modified AC showed the maximum adsorption performance [14]. Liu et al filled the pores of activated carbon with one-dimensional nano attapulgite (AT) and sintered to prepare activated carbon combined material with more abundant micropores [15]. The prepared composites exhibited good radon adsorption and regeneration performance, and the radon adsorption capacity increased over 25%.…”

Section: Introductionmentioning

confidence: 99%

Improving the Radon Adsorption Capacity of Activated Carbon by Liquid Nitrogen Modification

Deng

et al. 2023

J. Phys.: Conf. Ser.

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Radon is a naturally occurring radioactive inert gas that poses a significant threat to the human health. Coconut shell activated carbon has been verified to be the best radon adsorbing material, but its radon adsorption capacity still cannot meet the requirement of industrial applications. Activated carbon modification using liquid nitrogen is an effective method for improving the radon adsorption capacity, but it is necessary to determine the conditions for large-scale production. In this study, the influence of environmental temperature, container geometry, and amount of activated carbon and liquid nitrogen on the modification effect are examined. The results show that the activated carbon has the best modification effect when the container is placed in a water bath at 50 °C. The container geometry and activated carbon mass have a minor influence on the modification effect. Further, the radon adsorption capacity is increased by 36% when 6.5 L of liquid nitrogen is added to 1 kg of activated carbon. The characterization results reveal that the chemical structure and elemental content of the activated carbon do not change after modification, but the number of micropores is significantly increased, especially the micropores with a size of 0.5-0.6 nm, which is related to the radon adsorption capacity of the modified activated carbon. Overall, the liquid-nitrogen-based modification is a simple, environment-friendly, and low-cost method to improve the radon adsorption capacity of activated carbon, which can be used in the large-scale production of highly efficient radon adsorbents.

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“…Its ability to maintain a stable and high Rn adsorption level under conditions of high humidity is limited, restricting its widespread use in Rn-rich scenarios with high air humidity, such as water treatment plants, basements, and underground mines. Moreover, due to the lower distribution of Rn size-matching cavities, AC only exhibits moderate Rn capture efficiency and cannot remove Rn thoroughly [11,12]. Interestingly, the metal-organic framework (MOF) has emerged as an alternative resource for this application.…”

Section: Introductionmentioning

confidence: 99%

High-Throughput Computational Screening of Two-Dimensional Covalent Organic Frameworks (2D COFs) for Capturing Radon in Moist Air

et al. 2023

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Radon (Rn) and its decay products are the primary sources of natural ionizing radiation exposure for the public, posing significant health risks, including being a leading cause of lung cancer. Porous material-based adsorbents offer a feasible and efficient solution for controlling Rn concentrations in various scenes to achieve safe levels. However, due to competitive adsorption between Rn and water, finding candidates with a higher affinity and capacity for capturing Rn in humid air remains a significant challenge. Here, we conducted high-throughput computational screening of 8641 two-dimensional covalent organic frameworks (2D COFs) in moist air using grand canonical Monte Carlo simulations. We identified the top five candidates and revealed the structure–performance relationship. Our findings suggest that a well-defined cavity with an approximate spherical inner space, with a diameter matching that of Rn, is the structural basis for a proper Rn capturing site. This is because the excellent steric match between the cavity and Rn maximizes their van der Waals dispersion interactions. Additionally, the significant polarization electrostatic potential surface of the cavity can regulate the adsorption energy of water and ultimately impact Rn selectivity. Our study offers a potential route for Rn management using 2D COFs in moist air and provides a scientific basis for further experimentation.

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Activated carbon/attapulgite composites for radon adsorption

Cited by 14 publications

References 14 publications

Water Unexpectedly Impacts Both Thermodynamics and Kinetics of Rn Removal in HKUST-1

Water Unexpectedly Impacts Both Thermodynamics and Kinetics of Rn Removal in HKUST-1

Improving the Radon Adsorption Capacity of Activated Carbon by Liquid Nitrogen Modification

High-Throughput Computational Screening of Two-Dimensional Covalent Organic Frameworks (2D COFs) for Capturing Radon in Moist Air

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