Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer
The pH-responsive polymers, such as polyacrylamide (PAM), show distinct conformational states according to the pH of their environmental groundwater. Therefore, the interactions between clay–polymer and polymer–water molecules, which determine the yield stress of bentonite–polymer composites, can be...
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MDPI AG
2020-06-01
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| Online Access: | https://www.mdpi.com/1996-1944/13/11/2525 |
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| author | Hyunwook Choo Youngmin Choi Woojin Lee Changho Lee |
| author_facet | Hyunwook Choo Youngmin Choi Woojin Lee Changho Lee |
| author_sort | Hyunwook Choo |
| collection | DOAJ |
| description | The pH-responsive polymers, such as polyacrylamide (PAM), show distinct conformational states according to the pH of their environmental groundwater. Therefore, the interactions between clay–polymer and polymer–water molecules, which determine the yield stress of bentonite–polymer composites, can be affected by the pH of groundwater. This study aims to evaluate the effect of pH variation on the yield stress of calcium bentonite treated with PAM. The yield stresses (<i>τ<sub>y</sub></i>) of untreated and PAM treated clays were measured with varying volume fractions of solid (VF = 10–23%) and under varying pH conditions (pH = 7.6–9.6). In addition, the zeta potential was measured for both untreated and treated clays to figure out the change in the surface charge of the mineral surface due to PAM treatment. The results of this study demonstrate that <i>τ<sub>y</sub></i> for treated clay is higher than that for untreated clay at a given VF, because van der Walls attraction dominates electrostatic repulsion in the case of treated clay. Due to the change in conformational states of PAM and the consequent change in surface charge that comes with varying pH, the pH-dependent change in <i>τ<sub>y</sub></i> of treated clay is significantly different from that of untreated clay. |
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| format | Article |
| id | doaj.art-2ca640dd717c48daa122afe61516428c |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T19:26:30Z |
| publishDate | 2020-06-01 |
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| spelling | doaj.art-2ca640dd717c48daa122afe61516428c2023-11-20T02:30:24ZengMDPI AGMaterials1996-19442020-06-011311252510.3390/ma13112525Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive PolymerHyunwook Choo0Youngmin Choi1Woojin Lee2Changho Lee3Department of Civil Engineering, Kyung Hee University, Yongin 17104, KoreaInfra Engineering Team 2, SK Engineering & Construction Co., Ltd., Seoul 04534, KoreaSchool of Civil, Environmental, and Architectural Engineering, Korea University, Seoul 02841, KoreaDepartment of Civil Engineering, Chonnam National University, Gwangju 61186, KoreaThe pH-responsive polymers, such as polyacrylamide (PAM), show distinct conformational states according to the pH of their environmental groundwater. Therefore, the interactions between clay–polymer and polymer–water molecules, which determine the yield stress of bentonite–polymer composites, can be affected by the pH of groundwater. This study aims to evaluate the effect of pH variation on the yield stress of calcium bentonite treated with PAM. The yield stresses (<i>τ<sub>y</sub></i>) of untreated and PAM treated clays were measured with varying volume fractions of solid (VF = 10–23%) and under varying pH conditions (pH = 7.6–9.6). In addition, the zeta potential was measured for both untreated and treated clays to figure out the change in the surface charge of the mineral surface due to PAM treatment. The results of this study demonstrate that <i>τ<sub>y</sub></i> for treated clay is higher than that for untreated clay at a given VF, because van der Walls attraction dominates electrostatic repulsion in the case of treated clay. Due to the change in conformational states of PAM and the consequent change in surface charge that comes with varying pH, the pH-dependent change in <i>τ<sub>y</sub></i> of treated clay is significantly different from that of untreated clay.https://www.mdpi.com/1996-1944/13/11/2525polyacrylamidecalcium bentoniteyield stresspHzeta potential |
| spellingShingle | Hyunwook Choo Youngmin Choi Woojin Lee Changho Lee Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer Materials polyacrylamide calcium bentonite yield stress pH zeta potential |
| title | Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer |
| title_full | Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer |
| title_fullStr | Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer |
| title_full_unstemmed | Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer |
| title_short | Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer |
| title_sort | effect of ph variations on the yield stress of calcium bentonite slurry treated with ph responsive polymer |
| topic | polyacrylamide calcium bentonite yield stress pH zeta potential |
| url | https://www.mdpi.com/1996-1944/13/11/2525 |
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