Environmental Applications of Chemically Modified Clay Minerals, Volume II

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Clays and Engineered Mineral Materials".

Deadline for manuscript submissions: closed (20 October 2022) | Viewed by 4206

Special Issue Editor


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Guest Editor
Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
Interests: smectite; illite; kaolinite; iron; reduction; XRD; XRF; Mössbauer spectroscopy; FT-IR spectroscopy; short-wave Infrared spectroscopy
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Special Issue Information

Dear Colleagues,

On behalf of the Minerals Journal, I would like to invite you, one more time, to join me in the Special Issue related to the investigation of clay minerals with a focus on their environmental applications. Volume I has an incredible response in the scientific audience with many citations.

Clay minerals are natural materials with unique properties (large specific surface area, cation exchange capacity). For decades, most known clay mineral groups, smectites, and kaolinites have been investigated. Their usage ranges from cosmetics through paper and paints additives to environmental applications. Due to the negative layer charge, the smectites have a large specific surface area and cation exchange capacity. They are excellent natural adsorbents, but their properties can be enhanced by chemical modification to study their:

  1. Structural stability under extreme pH conditions (the isolation layers of toxic waste dumps and spent radioactive fuel storages - acid and alkali activation);
  2. Redox activity remediated contaminated waters and soils by industrial or agricultural discharges (chemical and biological redox activation of structural Fe);
  3. Reactivity with oversaturated saline solutions (geological clay barriers);
  4. Anti-inflammatory activity and other biological applications of clay minerals.

These topics are highly recommended for this Volume II of the Special Issue of the Minerals Journal, but other environmental utilizations of chemically modified clay minerals are also welcome. 

Finally, the overall goal of this Special Issue is to bring a message about the actual environmental applications of chemically modified clay minerals.

Dr. Martin P. Pentrak
Guest Editor

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Keywords

  • smectite
  • kaolinite
  • acid activation
  • redox activation
  • remediation
  • contamination
  • environmental application

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Published Papers (2 papers)

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Research

16 pages, 5484 KiB  
Article
Magnetic Nanosorbents Based on Bentonite and CoFe2O4 Spinel
by Nataliya Khodosova, Lyudmila Novikova, Elena Tomina, Larisa Belchinskaya, Alexander Zhabin, Nikolay Kurkin, Victoria Krupskaya, Olga Zakusina, Tatiana Koroleva, Ekaterina Tyupina, Alexander Vasiliev and Pavel Kazin
Minerals 2022, 12(11), 1474; https://doi.org/10.3390/min12111474 - 21 Nov 2022
Cited by 3 | Viewed by 1700
Abstract
New magnetic nanocomposite sorbents were obtained by doping natural bentonite with nanosized CoFe2O4 spinel (10 and 20 wt.%). Nanocrystals of cobalt ferrite were synthesized by a citrate burning method. The structure and physical-chemical properties of the composites were characterized by [...] Read more.
New magnetic nanocomposite sorbents were obtained by doping natural bentonite with nanosized CoFe2O4 spinel (10 and 20 wt.%). Nanocrystals of cobalt ferrite were synthesized by a citrate burning method. The structure and physical-chemical properties of the composites were characterized by XRD, XRF, TEM, BET, FTIR and Faraday balance magnetometry. During the formation of nanocomposites, 10–30 nm particles of cobalt ferrite occupied mainly the interparticle space of Fe-aluminosilicate that significantly changed the particle morphology and composite porosity, but at the same time retained the structure of the 2:1 smectite layer. A combination of two functional properties of composites, adsorption and magnetism has been found. The adsorption capacity of magnetic nanosorbents exceeded this parameter for bentonite and spinel. Despite the decrease in the adsorption volume, pore size and specific surface area of the composite material relative to bentonite, the sorption activity of the composite increases by 12%, which indicated the influence of the magnetic component on the sorption process. FTIR data confirmed the mechanism of formaldehyde sorption by the composite sorbent. The production of a magnetic nanosorbent opens up new possibilities for controlling the sorption processes and makes it possible to selectively separate the sorbent from the adsorption medium by the action of a magnetic field. Full article
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15 pages, 2214 KiB  
Article
Adsorption of Cs(I) and Sr(II) on Bentonites with Different Compositions at Different pH
by Yulia Izosimova, Irina Gurova, Inna Tolpeshta, Michail Karpukhin, Sergey Zakusin, Olga Zakusina, Alexey Samburskiy and Victoria Krupskaya
Minerals 2022, 12(7), 862; https://doi.org/10.3390/min12070862 - 07 Jul 2022
Cited by 6 | Viewed by 2040
Abstract
This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) and Sr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs and Sr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were [...] Read more.
This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) and Sr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs and Sr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were taken from the deposits Taganskoe (T), Dash-Salakhlinskoe (DS), Zyryanskoe (Z), and 10th Khutor (10H). The pH of bentonite aqueous suspensions, T and DS, exceeded 9 units. A less alkaline reaction was observed in bentonite suspensions Z and T with pH 8.94 and 7.70, respectively. Bentonites T and DS contained significant amounts of nonsilicate iron compounds, 1.0 and 0.5%, respectively. The recovery rate of the studied clays from aqueous solutions of Cs(I) and Sr(II) ions in concentrations from 0.25 to 5 mmol/L varied from 50% to 90% and decreased in the following order: “Ta-ganskoe” > “Dash-Salakhlinskoe” > “Zyryanskoe” > “10th Khutor” in the studied pH range. The main mechanism of Cs(I) and Sr(II) sorption in the studied pH range was cation fixation in the form of outer-sphere complexes on planar surfaces resulting from ion exchange. Increasing pH (pH > 6) enhanced pH-dependent positions, which allowed Cs(I) and especially Sr(II) ions to fix on them more firmly as inner-sphere complexes. At pH 9–10, Sr(II) could precipitate in the form of carbonates. The sorption of Cs(I) + and Sr(II) was accompanied by competitive interactions with proton at pH < 6 and Na+, Ca2+, Mg2+, and K+ cations at higher pH values. This competition was more apparent at concentrations of Cs(I)and Sr(II) in initial solutions < 0.5 mmol/L. The ability of bentonite T to sorb Cs(I) and Sr(II) in large amounts compared to the other bentonites was determined by high CEC values and charge of smectite T. Full article
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