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Minerals
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Crystal Structure, Surface Reactivity and Applications of Clay Minerals
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Crystal Structure, Surface Reactivity and Applications of Clay Minerals

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 (30 June 2022) | Viewed by 16982

Special Issue Editors

Prof. Dr. Qi Tao

E-Mail Website
Guest Editor
CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
Interests: formation and transformation of clay minerals; crystal growth of minerals; crystal structure and surface reactivity of minerals; mineral spectroscopy
Prof. Dr. Hongfei Cheng

E-Mail Website
Guest Editor
School of Earth Science and Resources, Chang’an University, Xi’an 710054, China
Interests: mineralogy; applied clay science; environmental science; soil science
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Clay minerals are a family of hydrous layered alumiosilicates, usually with a particle size of <2 μm, and they are the minerals most closely related to human activities. On the surface of the Earth, as important mineral components of soil and sediment, they affect geochemistry, environmental and ecology of the Earth’s critical zone. As natural nano/micron materials, clay minerals have wide applications in many fields.

We are pleased to invite you to contribute your new achievements to this Special Issue entitled “Crystal Structure, Surface Reactivity and Applications of Clay Minerals”. In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following: (1) characterization, computational simulation and structure refinement studies on clay minerals; (2) their synthesis/formation, stability and transformation, reactivity with environmental contaminants and (3) their advanced applications in material science, engineering, chemistry, agriculture, biological sciences, etc.

We look forward to receiving your contributions.

Prof. Dr. Qi Tao
Prof. Dr. Hongfei Cheng
Guest Editors

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 2400 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 minerals
  • Crystal structure
  • Crystal growth
  • Mineral stability
  • Surface reactivity
  • Organic Clay
  • Applied clay science
  • Smectites
  • Kaolinite
  • Palygorskite

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Published Papers (5 papers)

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Research

10 pages, 1874 KiB  
Article
Thermal Migration Behavior of Na+, Cu2+ and Li+ in Montmorillonite
by Zhenxiao Wu, Hao Zhao, Xuanping Zhou, Yang Wang, Kesheng Zuo and Hongfei Cheng
Minerals 2022, 12(4), 477; https://doi.org/10.3390/min12040477 - 13 Apr 2022
Cited by 11 | Viewed by 2623
Abstract
The main aim of this paper is to study the cation fixation sites in montmorillonite after heating at different temperatures. Montmorillonite was used to adsorb cations (Na+, Cu2+ and Li+) in the solution, and the montmorillonite-adsorbed cations were [...] Read more.
The main aim of this paper is to study the cation fixation sites in montmorillonite after heating at different temperatures. Montmorillonite was used to adsorb cations (Na+, Cu2+ and Li+) in the solution, and the montmorillonite-adsorbed cations were heated at different temperatures (unheated, 100 °C, 200 °C and 300 °C) for 25 h. Subsequently, the basal spacing of montmorillonite treated at different temperatures was monitored by X-ray diffraction (XRD). The exchangeable cationic content (Na+, Cu2+ and Li+) in montmorillonite was determined based on an inductively coupled plasma emission spectrometer (ICP-OES). In addition, the stretching and bending vibration changes in the OH group and the Si-O bond in montmorillonite were detected by Fourier transform infrared spectroscopy (FTIR). The vibration changes were related to the cation fixation sites. The XRD data showed that when the heating temperature reached 200 °C, the structure of montmorillonite adsorbing Li+ and Cu2+ ions completely collapsed, but the layer spacing of montmorillonite adsorbing Na+ decreased slightly, which indicated that Li+ and Cu2+ were more easily able to enter the crystal structure. The ICP-OES results showed that the contents of exchangeable Na+, Cu2+ and Li+ in montmorillonite decreased with the increase in heating temperature, and Li+ was more easily fixed by montmorillonite than Na+ and Cu2+. The FTIR data showed that when montmorillonite adsorbed with Li+ was heated at more than 200 °C, a new OH stretching vibration band appeared at 3971 cm−1, which may be caused by the migration of Li+ into the octahedral vacancy to form a local trioctahedral structure. Na+ has a large radius; it can only be fixed near the OH group and may not enter the tetrahedron/octahedron of montmorillonite. The number of charges carried by Cu2+ is high and the dehydration enthalpy of hydrated Cu2+ is high. When the heating temperature was greater than 200 °C, Cu2+ mainly entered the hexagonal cavity of the tetrahedron and caused slight changes in the OH bending vibration. The vibration of the Si-O bond hardly changed after montmorillonite adsorbed Na+, but the stretching vibration peak of the Si-O bond moved to the high value region after adsorbing Cu2+ and Li+, which was speculated to be related to the migration of Cu2+ and Li+ into the crystal structure. Full article
(This article belongs to the Special Issue Crystal Structure, Surface Reactivity and Applications of Clay Minerals)
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15 pages, 4591 KiB  
Article
Dispersibility of Kaolinite-Rich Coal Gangue in Rubber Matrix and the Mechanical Properties and Thermal Stability of the Composites
by Kenan Zhang, Hao Zhang, Linsong Liu, Yongjie Yang, Lihui Liu and Qinfu Liu
Minerals 2021, 11(12), 1388; https://doi.org/10.3390/min11121388 - 8 Dec 2021
Cited by 8 | Viewed by 2330
Abstract
The aim of this work was to investigate the dispersibility of kaolinite-rich coal gangue in rubber matrix, the mechanical properties and thermal stability of coal gangue/styrene butadiene rubber (SBR) composites, and to compare these properties to those of the same coal gangue but [...] Read more.
The aim of this work was to investigate the dispersibility of kaolinite-rich coal gangue in rubber matrix, the mechanical properties and thermal stability of coal gangue/styrene butadiene rubber (SBR) composites, and to compare these properties to those of the same coal gangue but had undergone thermal activation and modification. Several experimental techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric-differential scanning calorimetry (TG-DSC), laser-scattering particle analyzer were adopted to characterize the coal gangue particles and then the obtained composites. The results demonstrated the raw coal gangue (RCG) was mainly composed of kaolinite. Calcination led to amorphization of thermal activated coal gangue (ACG), increased hydrophilicity and void volume, and decreased pH. The grain size of ACG became coarser than RCG, but ACG turned loose confirmed by higher degree of refinement after grinding. Modification enhanced the hydrophobicity of the coal gangue and improved its dispersibility than fillers without modification. Calcined samples had better dispersibility than uncalcined fillers. Additionally, the coal gangue treated by calcinating, grinding and modifying (MGA) had the best dispersion in rubber matrix. Either calcination or modification could improve the mechanical properties and thermal stability of coal gangue filled rubber, while the performance of MGA reinforced SBR (MGA-SBR) was the best. The enhanced performance of the MGA-SBR was owed to better dispersion of particles as well as stronger interactions between particles and rubber macromolecules. Full article
(This article belongs to the Special Issue Crystal Structure, Surface Reactivity and Applications of Clay Minerals)
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12 pages, 1653 KiB  
Article
Keggin-Al13 Polycations: Influence of Synthesis and Intercalation Parameters on the Structural Properties of Al-Pillared Clays
by Anderson Parodia, Janaina A. Prasniski, Francine Bertella and Sibele B. C. Pergher
Minerals 2021, 11(11), 1211; https://doi.org/10.3390/min11111211 - 29 Oct 2021
Cited by 3 | Viewed by 1929
Abstract
Pillared clays are interesting materials with applications in catalysis and adsorption processes. To obtain these materials, several preparation procedures are necessary and must be optimized to tune the final properties of the resulting pillared clay. Therefore, this article reports the influence of synthesis [...] Read more.
Pillared clays are interesting materials with applications in catalysis and adsorption processes. To obtain these materials, several preparation procedures are necessary and must be optimized to tune the final properties of the resulting pillared clay. Therefore, this article reports the influence of synthesis parameters (temperature and concentration) of Keggin-Al13 polycations and different intercalation times (0.5 up to 72 h) on the structural properties of Al-pillared clays. The natural clays are from Brazil, and they are composed mainly of montmorillonite. By XRD, N2 sorption, XRF and 27Al NMR results of the Al-PILCs, we verified that the pillaring solution could be prepared at room temperature with an aging time of 24 h. For the cation exchange process, a period of at least 2 h is necessary to ensure the formation of pillared materials. The concentration of the Keggin-Al13 polycations was evaluated by using diluted pillaring solutions followed by applying re-pillaring procedures. After submitting the pillared clay to another pillaring process, the number of pillars in the interlamellar space increased; however, the micropore volume decreased concomitantly. Thus, by optimizing the synthesis conditions of the Keggin-Al13 polycations, Al-PILCs could be obtained with good values of basal spacing and specific surface area. Full article
(This article belongs to the Special Issue Crystal Structure, Surface Reactivity and Applications of Clay Minerals)
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18 pages, 12135 KiB  
Article
Fluctuations in Graphitization of Coal Seam-Derived Natural Graphite upon Approaching the Qitianling Granite Intrusion, Hunan, China
by Yingke Wu, Kuo Li, Zhaoguo Wang, Mianshu Hu, Haiyue Cao and Qinfu Liu
Minerals 2021, 11(10), 1147; https://doi.org/10.3390/min11101147 - 18 Oct 2021
Cited by 10 | Viewed by 2961
Abstract
The Lutang graphite deposit in Chenzhou, Hunan province, China, is a well-known coal seam-derived graphite (graphite formed from coal during its natural evolution) deposit with proven reserves of 9.5 million tons and prospective reserves of around 20 million tons (2015 data). The graphite [...] Read more.
The Lutang graphite deposit in Chenzhou, Hunan province, China, is a well-known coal seam-derived graphite (graphite formed from coal during its natural evolution) deposit with proven reserves of 9.5 million tons and prospective reserves of around 20 million tons (2015 data). The graphite occurs at an andalusite bearing sericite quartz chlorite metamorphic mudstone around a c. 530 km2 Qitianling granite intrusion. A set of coal seam-derived graphite samples from the Lutang graphite deposit in Hunan was examined by geochemical, crystallographic, and spectroscopic techniques to assess changes in the degree of graphitization approaching the intrusion. The carbon content, degree of graphitization, and Raman spectral parameters of series coal seam-derived natural graphite samples show a fluctuating increase with increasing proximity to the granite intrusion. The profile of geological structural features has a close spatial correlation with the variations in the degree of graphitization of series coal seam-derived natural graphite, and a strain-enhanced graphitization model is proposed. Moreover, the geographical distribution and the degree of graphitization are positively related to changes in the iron content of chlorite, suggesting a graphitization process promoted by mineral catalysis during metamorphism. A close spatial relationship exists between graphite mineral and chlorite occurrences when approaching the intrusive mass. The results of this research are important for understanding the role of tectonic stress and mineral catalysis on the genesis of coal-derived graphite. Full article
(This article belongs to the Special Issue Crystal Structure, Surface Reactivity and Applications of Clay Minerals)
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21 pages, 63288 KiB  
Article
Mineral Composition and Structural Characterization of the Clinoptilolite Powders Obtained from Zeolite-Rich Tuffs
by Ewelina Pabiś-Mazgaj, Tomasz Gawenda, Paweł Pichniarczyk and Agata Stempkowska
Minerals 2021, 11(10), 1030; https://doi.org/10.3390/min11101030 - 23 Sep 2021
Cited by 25 | Viewed by 5767
Abstract
Clinoptilolite is a precious zeolite mineral that has the most comprehensive physicochemical properties among all the zeolite group minerals. Due to these unique properties, clinoptilolite has a wide range of applications in many different industries. In Poland, the clinoptilolite occurs only as an [...] Read more.
Clinoptilolite is a precious zeolite mineral that has the most comprehensive physicochemical properties among all the zeolite group minerals. Due to these unique properties, clinoptilolite has a wide range of applications in many different industries. In Poland, the clinoptilolite occurs only as an accompanying mineral in the sedimentary rocks nearby Rzeszów. In Europe, the abundant clinoptilolite-bearing deposits are located in Slovakia and Ukraine, where clinoptilolite mineralization occurs in the volcanic tuffs. Due to clinoptilolite’s rare performance, it is extremely crucial to manage its deposits in a complementary manner. In this paper, the mineralogical and structural characterization of the clinoptilolite powders obtained by mineral processing of the clinoptilolite-rich tuffs from Slovakia and Ukraine deposits were discussed. The scope of research covered determination of the mineral composition of the tuffs, structural analysis of the clinoptilolite crystals, as well as textural and physical properties of the powders obtained by mineral processing of the tuffs. In addition, this paper includes the comparative study of the most significant zeolite deposits in the world and investigated clinoptilolite-rich tuffs. A wide spectrum of methods was used: X-ray powder diffraction (XRD), thermal analysis (DSC, TG), X-ray fluorescence (XRF), optical microscopy, Scanning Electron Microscopy (SEM-EDS), the laser diffraction technique, and low-temperature nitrogen adsorption/desorption. The test results indicated that the major component of the tuffs is clinoptilolite, which crystallized in the form of very fine-crystalline thin plates. The clinoptilolite mineralization in the Ukrainian and Slovakian tuffs exhibited a strong resemblance to the clinoptilolite crystals in Yemeni and Turkish tuffs. With respect to the mineral composition, the investigated tuffs showed excellent conformity with the Miocene white tuffs from Romania. The Ukrainian and Slovakian tuffs do not reveal the presence of the clay minerals, which is quite common for naturally occurring zeolite-rich rocks in various deposits in the world. The textural features together with mineral composition of the investigated samples incline that they are potentially suitable raw materials for the sorbent of petroleum compounds. Moreover, the obtained results can be useful indicators with respect to the crushing and compaction susceptibility of the Ukrainian and Slovakian clinoptilolite-rich tuffs. Full article
(This article belongs to the Special Issue Crystal Structure, Surface Reactivity and Applications of Clay Minerals)
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