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Special Issue "Application of Clays and Clay Minerals to Prevent Contamination"

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 2021) | Viewed by 6680

Special Issue Editor

Dr. Mercedes Regadío García
E-Mail Website1 Website2
Guest Editor
Department of Civil and Structural Engineering, The University of Sheffield, Broomhall, Sheffield S10 2TG, UK
Interests: reactive minerals; clay liners; degradation of pollutants

Special Issue Information

Dear Colleague,

Clays have interesting properties for important environmental applications by acting as sorbents, cation exchangers or flocculants. Accordingly, clays can be used in liners for waste disposal (included radioactive waste) and water purification. The advantages are that these natural materials are often readily available, abundant, and widespread. The disadvantage is the complexity of studying these materials and the mechanisms they trigger. We are looking for papers that provides recent advances in the effect and significance of clay properties on soil contamination. The work would expand the understanding of the mechanisms involved in the long-term immobilization and accumulation of pollutants and, especially, in the degradation or transformation of pollutants.

Dr. Mercedes Regadío García
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Clay interactions
  • Environmental Protection
  • Pollutant immobilization
  • Pollutant degradation

Published Papers (6 papers)

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Research

Article
The Effect of the Concentration of Copper Ions on the Unfrozen Water Content in Bentonites Measured with the Use of DSC Method
Minerals 2022, 12(5), 632; https://doi.org/10.3390/min12050632 - 17 May 2022
Viewed by 755
Abstract
Studies on changes of unfrozen water content in calcium bentonite from Slovakia, with various concentrations of copper ions, were carried out using the method of differential scanning calorimetry (DSC). In this study, the influence of molar concentration of copper(II) chloride solution (1 M, [...] Read more.
Studies on changes of unfrozen water content in calcium bentonite from Slovakia, with various concentrations of copper ions, were carried out using the method of differential scanning calorimetry (DSC). In this study, the influence of molar concentration of copper(II) chloride solution (1 M, 0.5 M, 0.25 M, 0.1 M), used to saturate clay, was analyzed, as well as the impact of copper ions contained in bentonite and how the copper concentration affects to changes of unfrozen water content versus temperature. The results suggest that new mineral phases originate in bentonite saturated with highly concentrated solutions due to the reaction with copper(II) chloride solutions. These minerals, identified based on XRD and SEM-EDS (X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy) studies, are from the atacamite group. ANOVA (Analysis of Variance) has shown a statistically significant relationship between the unfrozen water content and the molar concentration of the solution used to saturate bentonite and between the unfrozen water content and the content of copper ions in the bentonite. The analysis of multiple regression has shown that the change of unfrozen water content in copper bentonites is related to the temperature change, specific surface, and the concentration of copper ions in the clay. An empirical equation was developed to estimate the content of unfrozen water at a given negative temperature in Cu-bentonites, in which the specific surface and copper ions concentration in the bentonite are the main parameters. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Article
The Effect of Freeze-Thaw Cycling and the Initial Mass of Water on the Unfrozen Water Content of Calcium Bentonites Modified by Copper Ions
Minerals 2022, 12(1), 66; https://doi.org/10.3390/min12010066 - 05 Jan 2022
Cited by 1 | Viewed by 818
Abstract
This research was conducted with the use of the DSC method; it involved the examination of the unfrozen water content in two model (source) calcium bentonites (≥75% smectite), after one to three freeze-thaw cycles in the natural state, as well as after the [...] Read more.
This research was conducted with the use of the DSC method; it involved the examination of the unfrozen water content in two model (source) calcium bentonites (≥75% smectite), after one to three freeze-thaw cycles in the natural state, as well as after the ion exchange for a potentially toxic element (Cu2+). The freeze-thaw cycles do not affect the unfrozen water content at a given negative temperature in a statistically significant manner. However, a statistically significant influence of temperature, the initial mass of the water, and the clay type on the change of the unfrozen water content was found. Moreover, the empirical models of predicting the unfrozen water in the bentonite after the exchange for Cu2+ ion were created, for which the parameter was the mass of the water and the mass of the dry soil, at the temperature of −2 °C. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Article
Preparation of a Highly Porous Clay-Based Absorbent for Hazard Spillage Mitigation via Two-Step Expansion of Vermiculite
Minerals 2021, 11(12), 1371; https://doi.org/10.3390/min11121371 - 03 Dec 2021
Viewed by 1312
Abstract
Expanded vermiculite (eVMT) has been studied as a risk-free, general-purpose absorbent for liquid hazards due to its excellent thermal and chemical stability. Here, vermiculite was expanded by two steps: exfoliation by 30 wt% H2O2 treatment at 60 °C and subsequent [...] Read more.
Expanded vermiculite (eVMT) has been studied as a risk-free, general-purpose absorbent for liquid hazards due to its excellent thermal and chemical stability. Here, vermiculite was expanded by two steps: exfoliation by 30 wt% H2O2 treatment at 60 °C and subsequent expansion by microwave heating. This two-step expansion produced more homogenously separated concertina-like eVMTs with a higher total pore volume of 7.75 cm3 g−1 than the conventional thermal method. The two-step eVMT was found to be greatly superior to the thermal and commercial silver counterparts in hazardous liquid-uptake performance. The uptake was simply interpreted as a physical infilling process of a liquid into the eVMT pores, and the spontaneous hazard removal with a great capacity was discussed with the large pore volume of two-step eVMT and its suitable pore dimensions for capillary action. As a practical device, a prototype absorbent assembly made of these eVMTs demonstrated the successful mitigation of liquid hazards on an impermeable surface. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Article
A Statistical Evaluation to Compare and Analyze Estimations of the Diffusion Coefficient of Pertechnetate (99TcO4) in Compacted Bentonite
Minerals 2021, 11(10), 1075; https://doi.org/10.3390/min11101075 - 30 Sep 2021
Cited by 1 | Viewed by 772
Abstract
Various numerical methods have been being extensively used to estimate the diffusion parameters of pertechnetate (99TcO4) in compacted MX80 bentonite clay using through-diffusion (TD) techniques. In this study, an improved TD column test was applied, and the diffusion [...] Read more.
Various numerical methods have been being extensively used to estimate the diffusion parameters of pertechnetate (99TcO4) in compacted MX80 bentonite clay using through-diffusion (TD) techniques. In this study, an improved TD column test was applied, and the diffusion fluxes of tritium (HTO) as a non-reactive radionuclide, and 99TcO4 with various dry densities, were compared under the same experimental conditions. Similar results were obtained for the apparent diffusion coefficients of HTO and 99TcO4 using three estimation methods: a graphical method applying the asymptote calculation, an analytical solution using Lsqcurvefit installed in MATLAB, and the Marquardt–Levenberg optimization algorithm in the HYDRUS-1D inverse method. The statistical analysis showed that the densities using a one-way analysis of variance (ANOVA) for the three estimation methods ranged from 1200 to 2000 kg/m3, which indicated that there were no obvious differences between HTO and 99TcO4. In general, the diffusion parameters of 99TcO4 were lower than those for HTO due to anion exclusion effects and lower accessible porosity. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Article
Effectiveness of Carbaryl, Carbofuran and Metolachlor Retention in Soils under the Influence of Different Colloid
Minerals 2021, 11(9), 924; https://doi.org/10.3390/min11090924 - 26 Aug 2021
Cited by 1 | Viewed by 1210
Abstract
The affinity of different soil colloids to retain carbaryl, carbofuran and metolachlor in sandy loam and loam soil from mineral, surface horizons was investigated. The undisturbed soil samples and soils amended with colloids—kaolinite (K), montmorillonite (Mt), illite (Il), goethite (G), humic acid (HA)—were [...] Read more.
The affinity of different soil colloids to retain carbaryl, carbofuran and metolachlor in sandy loam and loam soil from mineral, surface horizons was investigated. The undisturbed soil samples and soils amended with colloids—kaolinite (K), montmorillonite (Mt), illite (Il), goethite (G), humic acid (HA)—were mixed with the pesticides for sorption–desorption studies. Their sorption magnitude in pristine soils followed the sequence metolachlor > carbaryl > carbofuran, with loam soil being a better pesticides retarder than sandy soil. The biggest magnitude of carbaryl sorption in light soil was observed in samples with the addition of HA (92.7%), Il (92.3%) and Ge (87.5%), whereas for carbofuran it was goethite (52.3%). Metolachlor uptake was significantly enhanced by 2:1 clays (Mt-85.0%, Il-69.4%), goethite (73.3%) and humic acids (75.4%). The loamy soil sorption capacity of the studied pesticides was blocked by the natural organic matter potentially due to the formation of organo-mineral complexes. HA (66.8%) was the most effective sorbent for carbaryl in the loamy soil, whereas Mt (55.1%) and HA (40.3%) for carbofuran. Metolachlor was retained to the same extent in all loamy soil variants (75.8–83.6%) and its desorption values were the lowest. Carbofuran demonstrated the greatest ability to leach among the studied chemicals. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Article
Molecule Diffusion Behavior of Tritium and Selenium in Mongolia Clay Rock by Numerical Analysis of the Spatial and Temporal Variation
Minerals 2021, 11(8), 875; https://doi.org/10.3390/min11080875 - 13 Aug 2021
Cited by 2 | Viewed by 988
Abstract
Clay rock in the Tamusu (TMS) area in the Inner Mongolia province is one candidate as a geological disposal site for highly radioactive waste in China. The diffusion behavior of HTO and Se(IV) in Tamusu clay rock was studied by through-diffusion (TD) experiments [...] Read more.
Clay rock in the Tamusu (TMS) area in the Inner Mongolia province is one candidate as a geological disposal site for highly radioactive waste in China. The diffusion behavior of HTO and Se(IV) in Tamusu clay rock was studied by through-diffusion (TD) experiments and numerical analysis to determine the spatial and temporal variation. A minimum error analysis was conducted to determine the HTO and Se(IV) diffusion coefficients in compacted TMS clay. The TD experimental results and numerical analysis showed that the diffusion of HTO and Se reached a steady state within 7 and 50 days, respectively, and the apparent diffusion coefficients (Da) decreased with the increases in the compacted density. In fact, there was retardation of Se diffusion in intact TMS clay rock. A two-site sorption model for Se was applied to simulate fast and slow sorption behavior quantitatively. Full article
(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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