Synthetic Hectorite: Preparation, Pillaring and Applications in Catalysis

Zhou, Chunhui; Tong, Dongshen; Li, Xiaonian

doi:10.1007/978-1-4419-6670-4_4

Cited by 11 publications

(5 citation statements)

References 102 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, two unique peaks related to Si–O stretching (1006 cm −1 ) and water deformation vibrations between layers (661 cm −1 and 1641 cm −1 ) were detected in hectorite. 20,22,39 The symmetric stretching of Mg–O was observed at 457 cm −1 , which corresponded to the octahedral units of hectorite-type clay minerals. 15 The incorporation of CTAB to Hec-40 and BHec-40 produced asymmetric and symmetric C–H strain vibrations of the CTAB at 2924 and 2850 cm −1 , respectively.…”

Section: Resultsmentioning

confidence: 99%

“…18 Hectorite can be synthesized from lithium (LiF or LiCl), magnesium (MgOH), and silica (SiO 2 ) in a molar ratio of 0.266 : 1.00 : 1.52, under controlled rates and low temperatures. 17,19,20 Inorganic cations on the surface can be modied through ion exchange with organic cations to form organophilic adsorbents. 21 Hectorite modied with cetyltrimethyl ammonium bromide increased the removal of Congo red and reactive orange 122.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hectorite-CTAB–alginate composite beads for water treatment: kinetic, isothermal and thermodynamic studies

et al. 2023

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hectorite-CTAB–alginate composite beads for water treatment: kinetic, isothermal and thermodynamic studies

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Pillaring, where a layered compound is transformed into a thermally stable micro- or mesoporous material by insertion of inorganic moieties separating individual clay layers, is distinguished from inorganic intercalated material by intracrystalline porosity from the lateral separation of intercalated particles. , The process of pillaring involves the following steps: the Na-activation of clay, the preparation of a pillaring solution, the exchange of polyoxycations in the pillaring solution with the hydrated interlayer cations, and calcination to form the stable pillared clay . Pillaring agents include polynuclear metal hydroxo complex ions, metal cluster complex ions, metal chelate complex ions, and positively charged colloidal particles . The mechanism of pillar functionalization in clay is unknown, however, the removal of protons from −OH groups of silicate layers after calcination causes a linking between the oxygen atoms of the pillar and the octahedral sheet cations in the clay …”

Section: Clay Functionalizationmentioning

confidence: 99%

Functionalized Clays for Radionuclide Sequestration: A Review

Wall

Maulden

Gager

et al. 2022

ACS Earth Space Chem.

View full text Add to dashboard Cite

Performance assessment of nuclear waste disposal options requires implementation of effective buffer materials. Buffer materials must meet longevity requirements and scavenge challenging radioisotopes, e.g., iodine-129 (I-129) and technetium-99 (Tc-99), both long-lived, highly mobile, anionic species in oxic environments. In many proposed nuclear waste repositories, heat generating radioactive waste will be surrounded by clay buffer material, which swells to fill the gap between the waste package and the host geology, restricting radionuclide transport to diffusive processes for several hundred years. The clay can be functionalized to further the limit release of Tc-99, as pertechnetate (TcO 4 − ), and I-129, as iodate (IO 3 − ) and iodide (I − ). Here, we review clay buffer functionalization and the potential to enhance sequestration of anionic radionuclides that have an increased risk of leaching out of a disposal facility. Functionalization with quaternary amines, nanosilver, bismuth-based materials, silane, and aluminum pillars have been demonstrated to improve the removal of targeted contaminants from solution. This review defines key research questions that remain: (i) can functionalized clay immobilize TcO 4 − , IO 3 − , and I − to the same extent as the reactive components themselves? (ii) Does functionalization affect the ability of the clay barrier to perform its safety functions of protecting the waste canister and limiting radionuclide transport? In addition to radionuclide retention, a multimodal analytical approach is required to assess functionalized clay performance, and recommended techniques are reviewed here. The key parameters that can influence radionuclide sequestration by functionalized clay are also evaluated. Theoretical approaches, including both density functional theory calculations and molecular dynamics simulations, can inform the energetics and kinetics of radionuclide interactions with functionalized clays. This combined experimental and theoretical approach can link atomistic and microscopic processes to predict the macroscopic physical properties of the functionalized clays.

show abstract

“…These are the depletion of the natural deposits, especially those with easy access for mining, and the occurrence of this clay as a mixture of several phases instead of a pure single phase. To overcome these problems, scientists in the fields of geology, material science, and geochemistry have been taking particular interest in the laboratory synthesis of clay minerals over recent decades [11][12][13]. In this work, we will consider a specific type of clay material in the Synthetic smectite group, called Fluorohectorite.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence study of water dynamics in Fluorohectorite clays using Molecular dynamics simulations

Mohammed¹,

Nigussa²

2023

Preprint

View full text Add to dashboard Cite

In this work, we have carried out molecular dynamics (MD) simulation techniques to study the diffusion coefficient of interlayer molecules at different temperature. Within the wider context of water dynamics in soils, and with a particular emphasis on clays, we present here the translational dynamics of water in clays, in a bi-hydrated states. We focus on temperatures between 293 K and 350 K, i.e., the range relevant to the environmental waste packages. A natural hectorite clay of interest is modified as a synthetic clay, which allows us to understand the determinantal parameters from MD simulations through a comparison with the experimental values. The activation energy E a determined by our simulation is [8.50 − 16.62] kJ mol . The calculated diffusive constants are in the order of 10 −5 cm 2 s −1 . The simulation results are in good agreement with experiments for the relevant set of conditions, and they give more insight into the origin of the observed dynamics.

show abstract

Synthetic Hectorite: Preparation, Pillaring and Applications in Catalysis

Cited by 11 publications

References 102 publications

Hectorite-CTAB–alginate composite beads for water treatment: kinetic, isothermal and thermodynamic studies

Hectorite-CTAB–alginate composite beads for water treatment: kinetic, isothermal and thermodynamic studies

Functionalized Clays for Radionuclide Sequestration: A Review

Temperature dependence study of water dynamics in Fluorohectorite clays using Molecular dynamics simulations

Contact Info

Product

Resources

About