Investigation of protonation and deprotonation processes of kaolinite and its effect on the adsorption stability of rare earth elements

Qiu, Sen; Qiu, Tingsheng; Yan, Huashan; Long, Qibang; Wu, Hao; Li, Xiaobo; Zhu, Dongxia

doi:10.1016/j.colsurfa.2022.128596

Cited by 15 publications

(13 citation statements)

References 30 publications

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“…This is the chemical Si/Al ratio and takes into account both framework and extra-framework Al (EFA) species present in the material. To estimate the amount of the framework Al content in the material, 27 Al direct polarization solid-state NMR experiments were conducted that indicated a Si/Al ratio of 25 (Figure S2). Hence, the material was termed MCM-22 (25).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Regolith-hosted ion-exchangeable natural clays, including kaolinite, halloysite, illite, etc., offer mineable sources of REEs, particularly heavy REEs (HREEs) like Dy, Ho, Er, and Yb . It is believed that natural clays like kaolinite capture REEs by ionic interactions via deprotonated surface hydroxyls. , One of the major issues is that the mechanism of REE adsorption by ionic adsorption clays remains largely unknown, despite the topic being a focus of effort by many research communities worldwide. Hence, a comprehensive understanding of the mechanisms underlying the proficiency of those ionic clays in retaining REEs promises invaluable insights into the realm of solid-phase adsorption.…”

Section: Introductionmentioning

confidence: 99%

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Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture

Chatterjee,

Han,

Kobayashi

et al. 2023

ACS Appl. Mater. Interfaces

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture

Chatterjee,

Han,

Kobayashi

et al. 2023

ACS Appl. Mater. Interfaces

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“…The equilibrium pH values of Nd 3+ , Eu 3+ , and Lu 3+ adsorbed on Kao and Mt were determined (Figure ). Due to the limited buffer capacity, the equilibrium pH remained almost unchanged when the initial pH was low . However, the equilibrium pH for Kao decreased and remained at a constant of 3.8 when the initial pH was higher than 4.…”

Section: Results and Discussionmentioning

confidence: 97%

“…Due to the limited buffer capacity, the equilibrium pH remained almost unchanged when the initial pH was low. 10 However, the equilibrium pH for Kao decreased and remained at a constant of 3.8 when the initial pH was higher than 4. A similar variation was found on Mt, while its equilibrium pH stabilized at 6.2, which is much higher than that for Kao.…”

Section: Adsorption Characteristics Of Nd 3+mentioning

confidence: 97%

“…Kao is a typical 1:1 silicate mineral, composed of a silicon–oxygen tetrahedral and an aluminum–oxygen octahedral . Kao is considered to have a permanent and variable pH-dependent charge on an external surface owing to isomorphous substitution and protonation/deprotonation of amphoteric surface hydroxyl groups. − Thus, REE ions are adsorbed through ion exchange, electrostatic attraction, surface complexation, and migration. , As for Mt, which is a 2:1 clay mineral, it has both permanent and variable pH-dependent charge in the interlayer and external surfaces, respectively, resulting in higher adsorption capacities than Kao . Additionally, surface properties such as points of zero charge (PZC), buffer pH, and specific surface area (SSA) of Kao and Mt are different, which are crucial for the adsorption of REE ions.…”

Section: Introductionmentioning

confidence: 99%

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Step-Leaching and Pre-Enrichment of Light and Heavy REEs from Kaolinite and Montmorillonite

Qiu

Yan

et al. 2022

ACS Sustainable Chem. Eng.

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Kaolinite (Kao) and montmorillonite (Mt) are the primary minerals present in ion-adsorption rare earth ores. Better understanding the adsorption/desorption characteristic for light and heavy rare earth elements (REEs) of Kao and Mt will be beneficial for the step-leaching and pre-enrichment of light and heavy REEs from ionadsorption REE ores. The experiments show that the more negative ζ potential and the larger specific surface area of Mt contribute to the higher adsorption capacity of REEs. The stability of REEs onto Kao and Mt increases with the increase in adsorption pH. There are obvious differences in the desorption characteristic among Nd 3+ , Eu 3+ , and Lu 3+ due to the different adsorption mechanisms. Lu 3+ almost adsorbed on Kao through electrostatic force, and its recovery is 88% when the desorption pH was higher than 4; however, the recoveries were only 50% for Nd 3+ and 56% for Eu 3+ , which interact with the Kao surface dominated by coordination bonds. However, the opposite desorption characteristic occurred on Mt. Based on these different desorption characteristics of light and heavy REEs, stepdesorption and pre-enrichment for Nd 3+ and Lu 3+ from Kao and Mt were feasible. In the first lixivium of Kao, the percentage of Lu 3+ is high, up to 68.4%, and Nd 3+ is enriched in the second lixivium, with a percentage of 73.9%. As for Mt, Lu 3+ is difficult to be desorbed and enriched in the second lixivium with a percentage of 87.7%.

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The effect of carbon coating on the arsenite sorption by magnetic carbon nanocomposites

Burbano,

Lassalle,

Horst

et al. 2024

Int. J. Environ. Sci. Technol.

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Arsenic pollution has emerged through anthropogenic activities and natural mineral leaching processes. This study aims to advance the use of magnetic carbon nanocomposites (MCNs) in the sorption of arsenic, studying the influence of feedstock and the presence of carbon coating on magnetic nanoparticles. Previous works have shown that post-pyrolysis treatment improves the stability of MCNs by reducing iron leaching due to the formation of a carbon coating that encapsulates the iron oxide nanoparticles. However, this carbon coating could influence the adsorption properties of MCNs. This investigation deals with arsenic adsorption by four MCNs prepared by co-precipitation of magnetite (Fe3O4) nanoparticle into four carbonaceous matrixes, followed by a post-pyrolysis treatment. The pristine carbonaceous matrixes used in the present work were commercial activated carbon (CAC), charcoal (CC), hydrochar from the orange residue (HCOR), and biochar from sunflower husk (BCSFH). Pristine carbonaceous materials and MCNs without post-pyrolyzed were also used as arsenic sorbents in water solutions. Additionally, kinetic studies were carried out to explore the sorption properties of different MCNs and pristine materials, concerning the removal efficiencies (expressed as a percentage) and adsorption capacities, determining the equilibrium time. The results demonstrated that the presence of magnetite increases the adsorption of arsenic, being higher in the case of materials obtained by direct co-precipitation than in materials subjected to a post-pyrolysis process. The presence of a carbon layerprotecting the magnetite slightly decreases the adsorption of arsenic.

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Investigation of protonation and deprotonation processes of kaolinite and its effect on the adsorption stability of rare earth elements

Cited by 15 publications

References 30 publications

Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture

Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture

Step-Leaching and Pre-Enrichment of Light and Heavy REEs from Kaolinite and Montmorillonite

The effect of carbon coating on the arsenite sorption by magnetic carbon nanocomposites

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