Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals
Pressure can tailor the properties of a material by changing its atomistic arrangements and/or crystal morphology. We have investigated the changes in the adsorption properties of kaolin group minerals as a function of pressure treatment in the gigapascal range. External pressures have been applied...
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MDPI AG
2019-10-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/9/10/528 |
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| author | Soyeon Kwon Huijeong Hwang Yongjae Lee |
| author_facet | Soyeon Kwon Huijeong Hwang Yongjae Lee |
| author_sort | Soyeon Kwon |
| collection | DOAJ |
| description | Pressure can tailor the properties of a material by changing its atomistic arrangements and/or crystal morphology. We have investigated the changes in the adsorption properties of kaolin group minerals as a function of pressure treatment in the gigapascal range. External pressures have been applied using a large volume press (LVP) to kaolinite (Al<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>) and halloysite (H<sub>4</sub>Al<sub>2</sub>O<sub>9</sub>Si<sub>2</sub>·2H<sub>2</sub>O), which represent natural 2D layered and 1D nanowire structures, respectively. Powdered samples have been compressed up to 3 GPa in 1 GPa steps at room temperature and recovered by up to ca. 0.35 g from each pressure step. Brunauer−Emmett−Teller (BET) measurements were conducted using N<sub>2</sub> gas to measure the specific surface area, pore size distribution, and pore volume of the pressure-treated samples. As the treatment pressure increased, kaolinite showed an increase in the adsorption behavior from nonpores to mesopores, whereas halloysite responded in an opposite manner to show a decrease in its adsorption capability. We discuss the contrasting effects of pressure-treatment on the two morphologically distinct kaolin group minerals based on field-emission scanning electron microscope (FE-SEM) images measured on each recovered material. We observed that the layers in kaolinite separate into smaller units upon increasing pressure treatment, whereas the tubes in halloysite become flattened, which led to the contrasting changes in surface area. Further study is in progress to compare this effect to when water is used as the pressure-transmitting medium. |
| first_indexed | 2024-04-12T19:26:18Z |
| format | Article |
| id | doaj.art-48d51981b67a472fb51450c7632e2b7c |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-04-12T19:26:18Z |
| publishDate | 2019-10-01 |
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| record_format | Article |
| series | Crystals |
| spelling | doaj.art-48d51981b67a472fb51450c7632e2b7c2022-12-22T03:19:28ZengMDPI AGCrystals2073-43522019-10-0191052810.3390/cryst9100528cryst9100528Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group MineralsSoyeon Kwon0Huijeong Hwang1Yongjae Lee2Department of Earth System Sciences, Yonsei University, Seoul 03722, KoreaDepartment of Earth System Sciences, Yonsei University, Seoul 03722, KoreaDepartment of Earth System Sciences, Yonsei University, Seoul 03722, KoreaPressure can tailor the properties of a material by changing its atomistic arrangements and/or crystal morphology. We have investigated the changes in the adsorption properties of kaolin group minerals as a function of pressure treatment in the gigapascal range. External pressures have been applied using a large volume press (LVP) to kaolinite (Al<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>) and halloysite (H<sub>4</sub>Al<sub>2</sub>O<sub>9</sub>Si<sub>2</sub>·2H<sub>2</sub>O), which represent natural 2D layered and 1D nanowire structures, respectively. Powdered samples have been compressed up to 3 GPa in 1 GPa steps at room temperature and recovered by up to ca. 0.35 g from each pressure step. Brunauer−Emmett−Teller (BET) measurements were conducted using N<sub>2</sub> gas to measure the specific surface area, pore size distribution, and pore volume of the pressure-treated samples. As the treatment pressure increased, kaolinite showed an increase in the adsorption behavior from nonpores to mesopores, whereas halloysite responded in an opposite manner to show a decrease in its adsorption capability. We discuss the contrasting effects of pressure-treatment on the two morphologically distinct kaolin group minerals based on field-emission scanning electron microscope (FE-SEM) images measured on each recovered material. We observed that the layers in kaolinite separate into smaller units upon increasing pressure treatment, whereas the tubes in halloysite become flattened, which led to the contrasting changes in surface area. Further study is in progress to compare this effect to when water is used as the pressure-transmitting medium.https://www.mdpi.com/2073-4352/9/10/528kaolinitehalloysitepressure treatmentspecific surface area |
| spellingShingle | Soyeon Kwon Huijeong Hwang Yongjae Lee Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals Crystals kaolinite halloysite pressure treatment specific surface area |
| title | Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals |
| title_full | Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals |
| title_fullStr | Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals |
| title_full_unstemmed | Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals |
| title_short | Effect of Pressure Treatment on the Specific Surface Area in Kaolin Group Minerals |
| title_sort | effect of pressure treatment on the specific surface area in kaolin group minerals |
| topic | kaolinite halloysite pressure treatment specific surface area |
| url | https://www.mdpi.com/2073-4352/9/10/528 |
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