The selective adsorption of tellurium in the aluminosilicate regions of AFI- and MOR-type microporous crystals

Kodaira, Tetsuya; Ikeda, Takuji

doi:10.1039/c4dt01028k

Cited by 4 publications

(9 citation statements)

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“…Carbon nanotubes (CNTs) and aluminophosphate (AlPO 4 ) materials are also considered hydrophobic and have one-dimensional channels, which could be useful models of biological channels. − Unusual water structures in CNTs have been reported. − Wang and co-workers indicated the temperature dependence of hydrophobic and hydrophilic properties of water in CNTs induced by water structure change . An anomalous ice phase was observed in CNTs at high pressure and even at ambient pressure in molecular dynamics simulations. , We also experimentally observed such ice-like clusters in CNTs under ambient conditions .…”

Section: Introductionmentioning

confidence: 67%

“…The O/C ratios of the 1, 2, 3, and 5 nm CNTs were 1.3, 0.5, 1.2, and 1.2%, respectively; thus, channel surfaces of CNTs have a highly hydrophobic nature. AlPO 4 materials also have a hydrophobic nature, estimated from water desorption temperature reported in the previous paper …”

Section: Resultsmentioning

confidence: 89%

“…AlPO 4 materials also have a hydrophobic nature, estimated from water desorption temperature reported in the previous paper. 33 Water vapor adsorption isotherms on CNTs and AlPO 4 are shown in Figure S1. Here, P and P 0 are the water vapor pressure and saturated water vapor pressure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Four CNTs were prepared using high-pressure CO conversion and chemical vapor deposition (CNTs were provided by Unidym Inc., Menio Park, CA; Hata group, AIST; NanoLab Inc., Waltham, MA) . AlPO 4 -5 and AlPO 4 -C provided by Kodaira were also used for supplying cylindrical nanoporous materials . The CNTs were named as 1, 2, 3, and 5 nm CNTs, according to the CNT diameters, which were obtained from transmission electron microscopy, reported in our previous paper .…”

Section: Methodsmentioning

confidence: 99%

“…46 AlPO 4 -5 and AlPO 4 -C provided by Kodaira were also used for supplying cylindrical nanoporous materials. 33 The CNTs were named as 1, 2, 3, and 5 nm CNTs, according to the CNT diameters, which were obtained from transmission electron microscopy, reported in our previous paper. 38 AlPO 4 -5 and AlPO 4 -C have cylindrical channels of 0.73 and 0.36 nm in diameter, respectively, based on their crystal structures.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Changing Water Affinity from Hydrophobic to Hydrophilic in Hydrophobic Channels

et al. 2015

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The behavior of water at hydrophobic interfaces can play a significant role in determining chemical reaction outcomes and physical properties. Carbon nanotubes and aluminophosphate materials have one-dimensional hydrophobic channels, which are entirely surrounded by hydrophobic interfaces. Unique water behavior was observed in such hydrophobic channels. In this article, changes in the water affinity in one-dimensional hydrophobic channels were assessed using water vapor adsorption isotherms at 303 K and grand canonical Monte Carlo simulations. Hydrophobic behavior of water adsorbed in channels wider than 3 nm was observed for both adsorption and desorption processes, owing to the hydrophobic environment. However, water showed hydrophilic properties in both adsorption and desorption processes in channels narrower than 1 nm. In intermediate-sized channels, the hydrophobic properties of water during the adsorption process were seen to transition to hydrophilic behavior during the desorption process. Hydrophilic properties in the narrow channels for both adsorption and desorption processes are a result of the relatively strong water-channel interactions (10-15 kJ mol(-1)). In the 2-3 nm channels, the water-channel interaction energy of 4-5 kJ mol(-1) was comparable to the thermal translational energy. The cohesive water interaction was approximately 35 kJ mol(-1), which was larger than the others. Thus, the water affinity change in the 2-3 nm channels for the adsorption and desorption processes was attributed to weak water-channel interactions and strong cohesive interactions. These results are inherently important to control the properties of water in hydrophobic environments.

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Section: Introductionmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 89%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Changing Water Affinity from Hydrophobic to Hydrophilic in Hydrophobic Channels

et al. 2015

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Uptake of gaseous thallium, tellurium, vanadium and molybdenum into anhydrous alum, Lascar volcano fumaroles, Chile

Sainlot

Vlastelić

Moune

et al. 2020

Geochimica et Cosmochimica Acta

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Formation of secondary sulphate minerals during the reaction between volcanic gases and rocks modulates the composition and flux of gaseous emanations. We report on the sub-surface formation of anhydrous alum (M I M III (X VI O4)2 with M I = NH4 + , Na + , K + ; M III = Al 3+ , Fe 3+ and X VI = S 6+) in the 330°C fumaroles of the Lascar volcano (Chile). The alum occurs as a few millimetres thick crust that grew internally by two-way diffusion of reaction gases and diffusive influx of rock cations within the crust. The average growth rate is estimated at ca. 0.3 m/day, based on the 19-year-long activity of the degassing fracture hosting the crust. The growth rate is controlled by the slow migration of the rock cations and decreases towards crust rim. The crust selectively concentrates Tl, V and Te (thousands of g/g) and to a lesser extent Mo (hundreds of g/g). The uptake of gaseous Tl, V and Mo is not due to saturation of the gas with Tl, V and Mo compounds but to the possibility for the elements to enter the crystal structure of alum: Tl + , V 3+ and Mo 6+ might substitute for the M I , M III and X VI ions, respectively. The process of Te uptake remains uncertain, but must be related to the incorporation of Tl and V with which Te tightly correlates. Thallium, V and Te concentrations increase by a factor > 20 from core to rim, where they reach 8760, 8508, and 1687 g/g respectively. This trend correlates with the decrease of crust growth rate. This indicates that the low rate of rock cations supply to the outer edge of the crust favours the substitution of Tl, V and Te in the crystal network. Such surface enrichment does not occur for Mo, because Mo competes with S, another element from the gas. This suggests that the surface of mature alum crust has a high adsorption capacity for those gaseous metals able to compensate for the lack of rockderived cations. Based on the composition of gases escaping from the fracture hosting the crust, it is estimated that the partition coefficients of Tl (3.310 7), V (1.110 7) and Te (0.610 7) between crust surface and gases are two to four orders of magnitude higher than for other volatile metals and metalloids. It follows that gases equilibrating with anhydrous alums lose between 77 and 95% of their initial Tl content, but less than 1% of Pb. Given the Tl emission rate of Lascar volcano (5 g/day), between 17 and 104 g of toxic Tl would deposit every day if all Lascar gases were to equilibrate with anhydrous alums.

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