The influence of structural and processing parameters of modifiers on the interlayer structure of modified montmorillonite

Chen, Hsuan-Hsuan; Thirumavalavan, Munusamy; Ma, Yijun; Lee, Jiunn‐Fwu

doi:10.1039/c5ra16010c

Cited by 9 publications

(2 citation statements)

References 27 publications

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“…It was due to the interlayer structure collapse of Mt caused by the over-high temperature. Thus, adsorption active sites on the surface of modified Mt were destroyed resulting from plugging the pores and reducing the specific surface area and pore volume at the same time, which greatly increased the barriers of adsorption of RE ions to a great extent [40]. Therefore, the optimum condition of modification temperature is applied as 90 • C in this study.…”

Section: Effect Of Reaction Conditions On the Preparation Of Modified Mtmentioning

confidence: 99%

Preparation of Modified Montmorillonite and Its Application to Rare Earth Adsorption

et al. 2019

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Montmorillonite, the major clay mineral in the tailings of weathered crust elution-deposited rare earth ores, was modified as an excellent adsorbent to enrich rare earth ions from solutions. It was demonstrated that 5% H 2 SO 4 could be used as a modifier to effectively enhance the adsorption capacity of montmorillonite after modifying for 3 h with a liquid:solid ratio of 40:1 at 90 • C. A superior modified montmorillonite over montmorillonite on adsorption performance was analyzed by the XRD, FT-IR, SEM, and BET (Specific Surface Area and Pore Diameter Analysis). The adsorption behaviors of La 3+ and Y 3+ on modified montmorillonite were fitted well with the Langmuir isotherm model and their saturated adsorption capacities were 0.178 mmol/g to La 3+ and 0.182 mmol/g to Y 3+ , respectively. Furthermore, (NH 4 ) 2 SO 4 as a common leaching agent in weathered crust elution-deposited rare earth ores, were successfully used as the eluent to recover the adsorbed rare earth ions. and edges and this is responsible for giving superior activity to Mt as an adsorbent [12]. Mt is formed by negatively charged silicate layers (about 1 nm) connected by electrostatic interaction. It belongs to the 2:1 clay minerals, the basic structure unit of which is composed of two silica tetrahedrons with an interlayer of aluminum oxygen octahedron. The atoms in this interlayer, which are common to both sheets, become oxygen instead of hydroxyl [13]. The isomorph substitution of Al 3+ by Si 4+ in the tetrahedral sheet and by Mg 2+ or Zn 2+ in the octahedral sheet results in a net negative charge on the clay surface, which makes it gain the ability to absorb certain cations. Moreover, Mt invariably contains exchangeable cations and anions held to the surface. The prominent cations and anions found between the sheets are K + , Na + , Mg 2+ , Cl − etc., and these ions are easily exchanged by other lower valence ions, which mainly carries out between the crystal layers and shows no effect on the Mt structure [14]. Adsorption of cations onto Mt involves two distinct mechanisms: (1) an ion exchange reaction at permanent charge sites, and (2) formation of complexes with the surface hydroxyl groups [15]. However, the industrial application of Mt is limited due to the crystal structure and negative charge of natural clays and interlayer impurity defects [16]. Single modifications of Mt through acid activation, inorganic salts, and cationic surfactant or polymer activation have attracted considerable interest and the adsorption capability of clay minerals can be successfully improved through modification [17].In industry, the RE concentration of leachate from weathered crust elution-deposited RE ores is approximately 0.2-2.0 g/L [11]. Although the precipitation and extraction are used to recycle RE, there is still some residual RE in the liquor with the concentration approximately below 0.15 g/L. To some extent, a large amount of RE resources is wasted. Therefore, the reuse of dumped tailings to enrich and recover RE in low-concentration solution is ...

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Section: Effect Of Reaction Conditions On the Preparation Of Modified Mtmentioning

confidence: 99%

Preparation of Modified Montmorillonite and Its Application to Rare Earth Adsorption

et al. 2019

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“…Though there are different nanofillers, the clay-based type has a specific advantage in improving the flame retardancy once it is composited with the base polymer materials [ 5 , 6 ]. The overall improvements in the thermomechanical characteristics of such clay/polymer nanohybrids can be ascribed to the uniform distribution of nanofillers across the polymer chains due to their higher surface characteristics and volume ratio, by which they can engage in better interaction with the polymer segments [ 7 , 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Nanofillers Based on Cetyltrimethylammonium-Modified Clays in a Polypropylene Nanocomposite

et al. 2022

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Nanocomposites of hydrophobic organo-clay/polypropylene (organo-clay/PP) were efficiently developed through a solution-blending technique. For this, we utilized various smectite clays as host agents; namely, Na-montmorillonite (Mt, ~1000 nm), Na-fluorine mica (Mica, ~1500 nm), and Na-hectorite (Ht, ~60 nm) with varied sizes, layer charges, and aspect ratios. Such clays were functionalized with cetyltrimethylammonium (CTA) bromide via an intercalation technique to obtain hydrophobic organic clays. The as-made clay particles were further mixed with a PP/xylene solution; the latter was removed to obtain the final product of the CTA-clay/PP nanocomposite. An X-ray diffraction (XRD) analysis confirmed that there were no characteristic (001) diffraction peaks for CTA-Mica in the PP nanocomposites containing CTA-Mica, assuring the fact that the Mica layers could be completely exfoliated and thereby homogenously composited within the PP. On the other hand, the CTA-Mt and CTA-Ht incorporated composites had broader (001) peaks, which might have been due to the partial exfoliation of CTA-Mt and CTA-Ht in the composites. Among the three CTA-clay/PP nanocomposites, the CTA-Mica nanohybrid showed an enhanced thermal stability by ~42 °C compared to the intact host polymer matrix. We also noted that when the CTA-Mica content was ~9 mass % in the nanocomposites, the Young’s modulus was drastically maximized to 69%. Our preliminary results therefore validated that out of the three tested clay-PP nanocomposites, the CTA-Mica nanofiller served as the best one to improve both the thermal and mechanical properties of the PP nanocomposites.

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Pyrolysis and its mechanism of organomontmorillonite (OMMT) influenced by different functional groups

Zhang

Cao

2018

J Therm Anal Calorim

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The influence of structural and processing parameters of modifiers on the interlayer structure of modified montmorillonite

Cited by 9 publications

References 27 publications

Preparation of Modified Montmorillonite and Its Application to Rare Earth Adsorption

Preparation of Modified Montmorillonite and Its Application to Rare Earth Adsorption

Effects of Nanofillers Based on Cetyltrimethylammonium-Modified Clays in a Polypropylene Nanocomposite

Pyrolysis and its mechanism of organomontmorillonite (OMMT) influenced by different functional groups

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