Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite
Modified calcium bentonite (Ca-bentonite) is extensively used in engineered barrier systems (EBSs) for municipal and industrial disposal sites due to its high swelling potential and low hydraulic conductivity. However, few studies have focused on the micromechanism of hydration and swelling under th...
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| Format: | Article |
| Language: | English |
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Wiley
2020-01-01
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| Series: | Advances in Polymer Technology |
| Online Access: | http://dx.doi.org/10.1155/2020/9361795 |
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| author | Yong Wan Dongdong Guo Xinminnan Hui Lei Liu Yuan Yao |
| author_facet | Yong Wan Dongdong Guo Xinminnan Hui Lei Liu Yuan Yao |
| author_sort | Yong Wan |
| collection | DOAJ |
| description | Modified calcium bentonite (Ca-bentonite) is extensively used in engineered barrier systems (EBSs) for municipal and industrial disposal sites due to its high swelling potential and low hydraulic conductivity. However, few studies have focused on the micromechanism of hydration and swelling under the effect of inorganic chemical solution. In this study, free swell index (FSI) and the type and content of modified Ca-bentonite bound water under the inorganic chemical solution were quantitatively studied by using the free swell test and nuclear magnetic resonance (NMR). According to the results, modification of sodium and polymer significantly increases the FSI of Ca-bentonite, bringing it close to that of natural sodium bentonite. In addition, the chemical stability of polymer-modified bentonite is significantly higher than that of sodium-modified bentonite but less than that of natural Na-bentonite. The FSI of modified Ca-bentonite decreases with the increase of cation valence and ionic strength. T2 distribution curves of the two types of modified bentonite are three-peak curves. With the increase of ionic strength, the content of total water and permeated hydrated water (accounting for 69%–95%) in bentonite decreases gradually, whereas the surface hydration water (accounting for 2%–31%) and free water content (accounting for 0–15%) increase. A uniform linear relationship exists between the FSI and corresponding total peak area of NMR (independent of ion valence, concentration, and bentonite type). Furthermore, a linear relationship exists between the FSI of the same type of bentonite and the T2 relaxation time. Research results can provide data and theoretical basis for quantitative analysis and mechanism of the hydration swelling of bentonite. |
| format | Article |
| id | doaj-art-54d2f9f0bab948e49a95cc2c1a562dd9 |
| institution | Kabale University |
| issn | 0730-6679 1098-2329 |
| language | English |
| publishDate | 2020-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Polymer Technology |
| spelling | doaj-art-54d2f9f0bab948e49a95cc2c1a562dd92025-02-03T06:05:30ZengWileyAdvances in Polymer Technology0730-66791098-23292020-01-01202010.1155/2020/93617959361795Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium BentoniteYong Wan0Dongdong Guo1Xinminnan Hui2Lei Liu3Yuan Yao4State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaWuhan Environment Investment & Development Co., Ltd, Wuhan 430019, ChinaModified calcium bentonite (Ca-bentonite) is extensively used in engineered barrier systems (EBSs) for municipal and industrial disposal sites due to its high swelling potential and low hydraulic conductivity. However, few studies have focused on the micromechanism of hydration and swelling under the effect of inorganic chemical solution. In this study, free swell index (FSI) and the type and content of modified Ca-bentonite bound water under the inorganic chemical solution were quantitatively studied by using the free swell test and nuclear magnetic resonance (NMR). According to the results, modification of sodium and polymer significantly increases the FSI of Ca-bentonite, bringing it close to that of natural sodium bentonite. In addition, the chemical stability of polymer-modified bentonite is significantly higher than that of sodium-modified bentonite but less than that of natural Na-bentonite. The FSI of modified Ca-bentonite decreases with the increase of cation valence and ionic strength. T2 distribution curves of the two types of modified bentonite are three-peak curves. With the increase of ionic strength, the content of total water and permeated hydrated water (accounting for 69%–95%) in bentonite decreases gradually, whereas the surface hydration water (accounting for 2%–31%) and free water content (accounting for 0–15%) increase. A uniform linear relationship exists between the FSI and corresponding total peak area of NMR (independent of ion valence, concentration, and bentonite type). Furthermore, a linear relationship exists between the FSI of the same type of bentonite and the T2 relaxation time. Research results can provide data and theoretical basis for quantitative analysis and mechanism of the hydration swelling of bentonite.http://dx.doi.org/10.1155/2020/9361795 |
| spellingShingle | Yong Wan Dongdong Guo Xinminnan Hui Lei Liu Yuan Yao Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite Advances in Polymer Technology |
| title | Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite |
| title_full | Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite |
| title_fullStr | Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite |
| title_full_unstemmed | Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite |
| title_short | Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite |
| title_sort | studies on hydration swelling and bound water type of sodium and polymer modified calcium bentonite |
| url | http://dx.doi.org/10.1155/2020/9361795 |
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