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Minerals
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Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge...
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Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice

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 (31 October 2023) | Viewed by 5552

Special Issue Editors

Dr. Mukuna Patrick Mubiayi

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Guest Editor
Mechanical Engineering Department, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa
Interests: materials characterization; clay and clay composites; uses of clay materials; removal of pollutants from aqueous solutions; friction stir welding; laser metal deposition
Dr. Adolph Anga Muleja

E-Mail Website
Guest Editor
Mechanical Engineering Department, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa
Interests: material science; water; energy; environment; membrane; catalysis; nanotechnology; process synthesis/engineering
Dr. Thabo Falayi

E-Mail Website
Guest Editor
Engineering Department, Namibia University of Science and Technology, Windhoek 13388, Namibia
Interests: solid waste solidification; adsorptive wastewater remediation

Special Issue Information

Dear Colleagues,

Clay materials are a type of fine-grained natural soil material containing minerals such as kaolinite, smectite, chlorite, and micas. It has been established that the knowledge of the properties of natural materials is of importance and it has led to the extensive use of those materials for numerous applications. Therefore, it is warranted that the properties of natural clay materials from various geographic locations are investigated and presented. This would result in their usage in many applications including water/wastewater remediation (removal of toxic pollutants), fabrication of construction materials (bricks and tiles), and in the cosmetic industry (Sunscreen). Furthermore, clay soils are abundant, natural materials, and sustainable. Their usages would provide sustainable ways/green techniques to produce numerous products for specific applications ranging from water treatment to construction. Moreover, clay is used as raw materials and as composites. When applied as the latter, clay is mixed with other materials including generated wastes from industries such as agriculture (e.g., palm kernel shell) and mining (e.g., jarosite) and energy (e.g., fly ash) to form composite materials. The various applications of clay composites comprise constructions (i.e., bricks, roads); cosmetics (beauty products); ceramic/ceramic filters for water/wastewater treatment; adsorption of hydrogen (H2) and carbon dioxide (CO2). It has been observed (in the open literature) that the characteristics of many clay materials from some locations situated in continents such as Africa and Asia have not been well documented. Further investigations on natural clays from locations (Europe, America, and Australia) where some publications are readily available would enhance and might shed some new insights into the natural clays. Thus, it is of importance for researchers to analyze the clay materials from those locations to add the results to the body of knowledge. Anticipatively, this will enable their extensive use for specific applications in solving and providing solutions to some of the problems locally and globally. This Special Issue covers the characteristics of clay, clay composite materials, and their usages. To utilize natural clay for various applications, it is imperative to know its characteristics using various techniques including diffraction, microscopy, spectroscopy, optical and thermal. Manuscripts covering the synthesis, the characterizations, and applications of clay and clay composites materials are welcome.

Dr. Mukuna Patrick Mubiayi
Dr. Adolph Anga Muleja
Dr. Thabo Falayi
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 and clay minerals 
  • composite materials 
  • removal of pollutants 
  • toxic elements 
  • physicochemical properties 
  • geochemical characteristics 
  • clay/wastes composite materials 
  • ceramics 
  • cosmetics 
  • construction materials

Published Papers (4 papers)

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Research

20 pages, 2337 KiB  
Article
Preparation of Melamine Formaldehyde Foam and a Melamine-Formaldehyde-Organo-Clay Nanocomposite and Hybrid Composites
by Ahmet Gürses and Elif Şahin
Minerals 2023, 13(11), 1407; https://doi.org/10.3390/min13111407 - 2 Nov 2023
Viewed by 1208
Abstract
Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite [...] Read more.
Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite (MFNC) and also pumice as primary filler, and gypsum, kaolinite and a hollow glass sphere as secondary filler. It also focuses on the study of some mechanical properties and thermal conductivities, as well as their microscopic and spectroscopic characterization. For this, firstly, organo-clay was prepared with the solution intercalation method using montmorillonite, a cationic surfactant and long-chain hydrocarbon material, and then was produced using a melamine formaldehyde nanocomposite with in situ synthesis using a melamine formaldehyde pre-polymer and organo-clay. Finally, hybrid composites were prepared by blending various minerals and the produced nanocomposite. For morphological and textural characterization, both FTIR spectroscopy and XRD spectra, as well as SEM and HRTEM images of the raw montmorillonite (MMT), organo-montmorillonite (OMMT), pure polymer (MF) and prepared hybrid composites, were used. Spectroscopic and microscopic analyses have shown that materials with different textural arrangements and properties are obtained depending on effective adhesion interactions between polymer–clay nanocomposite particles and filler grains. Mechanical and thermal conductivity test results showed that melamine-formaldehyde-organo-clay nanocomposite foam (MFCNC) exhibited a very good thermal insulation performance despite its weak mechanical strength (λ: 0.0640 W/m K). On the other hand, among hybrid composites, it has been determined that the hybrid composite containing hollow glass beads (MFCPHHC) is a material with superior properties in terms of thermal insulation and mechanical strength (λ: 0.642 W/m K, bulk density: 0.36 g/cm3, bending strength: 228.41 Mpa, modulus of elasticity: 2.22 Mpa and screw holding resistance: 3.59 N/mm2). Full article
(This article belongs to the Special Issue Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice)
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17 pages, 5514 KiB  
Article
Preparation and Characterization of Mercapto-Functionalized Calcined Attapulgite and Its Removal of Pb (II) and Cd (II) Solution
by Jiaqian Zhang, Zhe Wang, Ying Luo, Zhenlong Zhang, Xiyang Feng, Qiuping Zeng, Duan Tian, Chao Li, Yongde Zhang and Shu Chen
Minerals 2023, 13(10), 1337; https://doi.org/10.3390/min13101337 - 17 Oct 2023
Viewed by 1136
Abstract
To enhance the sorption efficacy of attapulgite for heavy metals, mercapto-functionalized attapulgite (ATP-SH) was synthesized with mercaptan functional groups. When the mass-to-volume ratio of calcined attapulgite (ATP-C) to 3-Mercapropyltrimethoxysilane (MPTMS) was 1 g:0.5 mL (ATP-SH-0.5) and the pH was set to 8, a [...] Read more.
To enhance the sorption efficacy of attapulgite for heavy metals, mercapto-functionalized attapulgite (ATP-SH) was synthesized with mercaptan functional groups. When the mass-to-volume ratio of calcined attapulgite (ATP-C) to 3-Mercapropyltrimethoxysilane (MPTMS) was 1 g:0.5 mL (ATP-SH-0.5) and the pH was set to 8, a strong adsorption capacity for Cd (II) and Pb (II) was demonstrated. This indicates excellent adsorption performance for these heavy metals. ATP-SH-0.5 exhibited a maximum adsorption capacity of 43.81 mg/g and 274.83 mg/g for Cd (II) and Pb (II), respectively, in a single ion system. In a binary ion system, the maximum adsorption capacity was 31.86 mg/L and 254.45 mg/L for Cd (II) and Pb (II), respectively. Various characterizations and experiments showed that the adsorption of Cd (II) and Pb (II) onto ATP-SH-0.5 involves ion exchange reactions involving hydroxyl and thiol functional group complexation reactions. This adsorption process follows a single-molecule layer adsorption mechanism. XPS results indicate that hydroxyl and grafted thiol functional groups on the surface of mercapto-functionalized attapulgite participated in surface complexation reactions with Cd (II) and Pb (II), resulting in the formation of Cd-S and Pb-S species. Overall, this study provides a promising mercapto-functionalized modification material for the remediation of polluted water and soil. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice)
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0 pages, 5743 KiB  
Article
Synergistic Effects of Red Clay and Lime for Improving Phyllite Soil
by Linhao Zhao, Xiushao Zhao, An Cheng, Zixi Chen, Jianglong Rao and Linli Mo
Minerals 2023, 13(10), 1321; https://doi.org/10.3390/min13101321 - 12 Oct 2023
Viewed by 806
Abstract
Phyllite soil and red clay belong to the soils that negatively impact the engineering performance of railway subgrade and may cause subgrade bulges, uneven subgrade settlement, and other subgrade distresses. In order to make full use of these two soils, a collaborative improvement [...] Read more.
Phyllite soil and red clay belong to the soils that negatively impact the engineering performance of railway subgrade and may cause subgrade bulges, uneven subgrade settlement, and other subgrade distresses. In order to make full use of these two soils, a collaborative improvement plan was proposed. A series of tests were conducted to analyze the synergistic effects of lime and red clay on the improvement of phyllite soil. The tests included the no loading swelling ratio, swelling pressure, consolidation, and direct shear tests. Additionally, scanning electron microscopy was used to investigate the role of lime and red clay in soil improvement. The test results show that a red clay ratio of 60% + lime content of 3% is the optimal composite improvement scheme. The scheme led to a 93% reduction in the no loading swelling ratio and an 88% reduction in swelling pressure. Additionally, cohesion, the internal friction angle, and the compression modulus increased by 345%, 73%, and 373%. Red clay and lime had weak synergistic improvement effects on the no loading swelling ratio, the swelling pressure, and the internal friction angle of phyllite soil, that is, the synergistic improvement effect of red clay and lime was less than the sum of the single improvement effect but greater than the single improvement effect. Red clay and lime had a strong synergistic improvement effect on the cohesion and the compression modulus of phyllite, that is, the synergistic improvement effect of red clay and lime was greater than the sum of the single improvement effect. The microstructure analysis test results show that red clay can fill the pores of phyllite soil and improve its immediate strength. Through hardening and cementation, lime can enhance the strength of phyllite soil as well as address the issue of the reduced engineering properties of phyllite soil and red clay when exposed to water. Red clay and lime promote each other’s reactions and have a synergistic improvement effect on phyllite soil. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice)
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15 pages, 9202 KiB  
Article
Response of High Swelling Montmorillonite Clays with Aqueous Polymer
by Guru Prasad Panda, Alireza Bahrami, T. Vamsi Nagaraju and Haytham F. Isleem
Minerals 2023, 13(7), 933; https://doi.org/10.3390/min13070933 - 13 Jul 2023
Cited by 2 | Viewed by 1422
Abstract
Expansive clays containing mineral montmorillonite exhibit swelling and shrinkage due to variations in the moisture content, leading to significant distresses. There has been a growing interest in chemical and polymer additives treated for high swelling montmorillonite clays in recent years. However, limited attention [...] Read more.
Expansive clays containing mineral montmorillonite exhibit swelling and shrinkage due to variations in the moisture content, leading to significant distresses. There has been a growing interest in chemical and polymer additives treated for high swelling montmorillonite clays in recent years. However, limited attention has been paid to the effect of polyacrylamide on the soil’s swelling behavior. Moreover, nontraditional methods of the soil treatment are applied for the rapid stabilization of soil. In this article, polyacrylamide polymer is used as an additive to expansive clays to control the swelling phenomenon. Three different percentages—2.5%, 5%, and 7.5%—of polymer are blended with oven-dried soil to determine Atterberg limits, compaction features, and swelling characteristics. Additionally, electrical impedance measurement is conducted on treated soil samples with different moisture contents. The electrical resistance of soils and polymer-treated soils is measured based on the electrical resistivity correlation of soils. Tests results for soils stabilized with polyacrylamide show that swelling is significantly reduced with increasing the additive content. Moreover, the addition of polymer improves resistivity of soil. Aqueous polyacrylamide can be utilized as an effective stabilization additive to enhance properties of expansive clays. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice)
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