Correlation of aspect ratio of montmorillonite nanosheets with the colloidal properties in aqueous solutions

Chen, Licai; Zhao, Yunliang; Chen, Tianxing; Bai, Haoyu; Zhang, Tingting; Li, Hongqiang; An, Qing; Song, Shaoxian

doi:10.1016/j.rinp.2019.102526

Cited by 19 publications

(12 citation statements)

References 36 publications

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“…This could probably be attributed to the opposite charges of basal and edge surfaces in the low pH environment of montmorillonite as previously reported by others. 13,29 In the aqueous environment, the interlayer cation of montmorillonite becomes increasingly hydrated, thereby resulting in more water entering into the interlayers. 42 Such hydration phenomena can lead to swelling of clay and delamination resulting in thinner platelets compared to those of kaolinite and illite.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Moreover, because it is widely accepted that the basal surfaces of most clays have permanently negative charges, the ZP of clays as a function of pH (Figure S5) confirmed that the edge surfaces of montmorillonite and illite carried positive charges in such an acidic environment (pH = 4.5). 6,29 Although illite has a similar 2:1 structure and edge charge distribution to those of montmorillonite, heavy coating occurred in the presence of montmorillonite, while the illite particles barely adhered to pyrite surface. Such a great difference between the two clay minerals could be attributed to the poor dispersion and swelling properties of illite compared to those of montmorillonite.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The procedures of measurement have been described in a former publication by the authors. 29 The particle size distribution of minerals was determined using the APA 2000 laser particle analyzer (Malvern, UK).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

et al. 2020

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It is widely acknowledged that clay minerals have detrimental effects on the process of flotation, but the mechanisms involved are still not fully understood. In this work, the effects of montmorillonite, kaolinite, and illite on pyrite flotation were investigated from the perspective of various structures of clay minerals. Flotation tests suggested that the detrimental effect of clay minerals on the flotation of pyrite increased as follows: montmorillonite > kaolinite > illite. With the help of rheology measurements, it was found that montmorillonite significantly increased pulp viscosity, which in turn substantially reduced pyrite recovery and grade. Scanning electron microscopy (SEM) images suggested that montmorillonite formed the “house-of-cards” structure by edge-to-edge and edge-to-face contact, while kaolinite and illite platelets were associated mainly in the face-to-face mode. In addition, it was clearly observed by SEM–energy dispersive spectrometry that montmorillonite and kaolinite coat on the pyrite surfaces, which would lower the surface hydrophobicity of pyrite. Kaolinite covered much larger area of pyrite surface than montmorillonite owing to the positive charge occurring at the exposed aluminum–oxygen octahedral sheet of kaolinite. Although illite has a similar 2:1 structure to montmorillonite, it showed little or no effect on pyrite flotation, which was attributed to its poor swelling nature. These findings shed light on the root cause of the adverse effect of clay minerals on pyrite flotation and are expected to provide theoretical guidance for mitigating the negative effects on flotation caused by clays.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

et al. 2020

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“…Hence, the aspect ratio (L/W) of the MMT particles was calculated as 14 and 20 for dispersions prepared by UT-and BM-processes, respectively. These values are at the lower end of a range from 10 to 1,000, reported for the aspect ratio of MMT containing clay particles (50)(51)(52)(53)(54). The variations in L, T, and W, leading to this broad range, are due to the differences in natural abundance in clay minerals, as well as the different preparation methods.…”

Section: Particle Size Distribution and Aspect Ratiomentioning

confidence: 83%

“…The variations in L , T , and W , leading to this broad range, are due to the differences in natural abundance in clay minerals, as well as the different preparation methods. Whereas high barriers are normally reached with high aspect ratios ( 48 , 49 , 55 ), nanolacquers with these particles are limited in viscosity, total solid content, and mixing ratio ( 54 ). That means an increased size in the aspect ratio always goes along with an increase in viscosity of the nanolacquer.…”

Section: Resultsmentioning

confidence: 99%

Nanocomposite Coatings Based on Polyvinyl Alcohol and Montmorillonite for High-Barrier Food Packaging

et al. 2022

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Materials with high barrier properties against oxygen are required for the packaging of many sensitive foods. Since commodity polymers lack these properties, additional barrier materials are used in plastic-based barrier packaging. These are usually more expensive than commodity polymers and, in higher fractions, also make recycling more difficult. Current developments, therefore, aim at barrier layers that are as thin as possible but retain the barrier properties. One approach is to incorporate nanoparticles into these layers. In this study, the barrier properties of nanocomposite coatings, consisting of unmodified polyvinyl alcohol (PVA), and dispersed stick-shaped halloysite (Hal) or platelet-shaped montmorillonite (MMT) silicate nanoparticles, were investigated. The PVA was dissolved in aqueous nanoparticle dispersions, which were prepared by mechanical shearing, to produce the so-called “nanolacquer.” Nanolacquers with nanoparticle concentrations of 7, 30, and 47 vol% with respect to PVA were applied in a single process step with k-bar on a polypropylene substrate film. The integration of 30 vol% platelet-shaped MMT enhances the barrier performance in comparison to pure PVA by a factor of 12 and 17 for oxygen and helium, respectively. Scanning electron microscopy (SEM) shows a homogeneous distribution and a parallel alignment of the nanoparticles within the coated layer. An increase in the crystallinity of PVA was observed due to the nanoparticle integration as demonstrated by x-ray diffraction (XRD) measurements. The investigation by Fourier transform infrared (FTIR) spectroscopy and the activation energy of the permeation coefficient indicate an interaction between the nanoparticles and the PVA. The theoretically calculated values for barrier enhancement accord well with the experimental values, which emphasizes that the gas barrier improvement for oxygen and helium is mainly dominated by the tortuous path effect.

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The Sensitive Optical pH Sensor Based on the Complex of Nanosheet and Carbon Dots

et al. 2022

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The requirement to non-invasively quantify H + is gradually increasing. In this regards, optical pH sensors based on fluorescent materials have advantages. However, the stability and sensitivity of currently used chromophores still need to be further improved to meet the continuous increase in actual demand for pH measurement. Here, we proposed to employ Montmorillonite (MMT) nanosheets as matrix and carbon dots (CD) as chromophores to fabricate a new complex. The as-prepared MMT-CD have the following advantages: 1) the aggregation of CD is effectively reduced, leading to the effectively improved fluorescence performance; 2) MMT-CD has good light stability and storage stability; 3) as-prepared the fluorescence pH sensor shows good response to pH, high sensitivity, and wide linear range. Therefore, MMT-CD materials have great potential in the rapid and sensitive sensing of pH value.

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Correlation of aspect ratio of montmorillonite nanosheets with the colloidal properties in aqueous solutions

Cited by 19 publications

References 36 publications

Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

Role of Montmorillonite, Kaolinite, or Illite in Pyrite Flotation: Differences in Clay Behavior Based on Their Structures

Nanocomposite Coatings Based on Polyvinyl Alcohol and Montmorillonite for High-Barrier Food Packaging

The Sensitive Optical pH Sensor Based on the Complex of Nanosheet and Carbon Dots

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