Clay Composites Research Articles

Phosphate removal by acid-activated and chitosan-composite clayey soils

Phosphate is a vital nutrient for aquatic organism growth, but excessive levels can lead to eutrophication, with detrimental effects on receiving water bodies. Adsorption using clay soils can address phosphate release and has gained attention owing to its cost-efficiency and environmental friendliness. To overcome the limited phosphate adsorption capacity of clay soils due to surface charges, the combined effects of acid activation and composite formation with chitosan were investigated. Kaolin and bentonite were selected for acid activation, while chitosan varieties with low, medium, and high molecular weights were chosen for composite formation. Batch tests were individually conducted on acid-activated clay soils and composites of acid-activated clay soils with chitosan over 24 h, varying the initial phosphate concentrations. For acid activation, clay soils were treated with 6N hydrochloric acid, whereas composite formation was achieved via combination with each chitosan variant. Acid-activated kaolin and bentonite individually exhibited phosphate removal efficiencies ranging 99.8–79.8% and 97.1–47.2%, respectively. Among their respective composites, acid-activated kaolin with medium-molecular-weight chitosan and acid-activated bentonite with low-molecular-weight chitosan had the highest phosphate removal efficiencies. Therefore, in contrast to kaolin, acid activation or composite formation of acid-activated bentonite with chitosan can improve its phosphate removal efficiency.

An optimized complementary design based on trilayer graphene oxide and clay composites for three stimuli responsive actuator

To promote the practical development of actuators, it is urgent to develop new multi-responsive actuators. Asymmetric bilayer actuators were reported to be dual-responsive, which can be driven by humidity and light. However, it remains a great challenge to develop rational designs for fabricating high-performance multi-responsive actuators. Here, we propose an optimized complementary design for three stimuli responsive actuators that can respond to multiple organic vapors, humidity, and light. The actuator is designed to achieve complementarity through a trilayer construction with graphene oxide (GO) in the middle layer, and with montmorillonite (MMT) and biaxially-oriented polypropylene (BOPP) on both sides, utilizing their hygroscopicity, organic vapor absorption, light absorption and thermal expansion capabilities. The maximum bending curvatures of the actuator under humidity, organic vapor and light stimulation conditions are 6.60 cm-1, 4.12 cm-1 and 2.59 cm-1 respectively, which are better than that of mixed GO-MMT/BOPP bilayer actuators. To reveal the kinetics of actuation, the actuation speed, temperature and mass during the deformation process are studied, which behave in sync with the bending curvature. Finally, a wireless intelligent claw and an organic-vapor leakage alarm are demonstrated based on these actuators. This study will provide an enlightening reference for multi-responsive actuators and promote their practical development.

Oxygen vacancy-enriched kaolinite/WO3-x nanocomposites exhibiting enhanced photo-synergetic H2O2 activation for tetracycline degradation boosted by hydroxyl groups and exciton

The efficient activation of H2O2 into hydroxyl and superoxide radicals with strong oxidizing power is an often overlooked but challenging issue. In this study, oxygen vacancy-enriched kaolinite/WO3-x composites (KW7) were prepared by a three-step method. Benefiting from abundant oxygen vacancies and surface hydroxyl groups, KW7 composite exhibited excellent photocatalytic H2O2 activation performance. The TC degradation experiments revealed that the KW7/H2O2/hv system exhibited the highest rate constant (k) of approximately 0.1561 min−1, which was 9.4, 5.3, and 5.1-fold greater than those of Kaol/H2O2/hv, WO3/H2O2/hv, and WO3-x/H2O2/hv, respectively. Furthermore, the k value was found to be 5.6 and 4.1 times higher than those observed in the KW7/hv and KW7/H2O2 systems, respectively. The investigation into the underling mechanism of reactive oxygen species generation reveals that, the presence of a high concentration of oxygen vacancies in KW7 results in the increased number of defect energy levels, which leads to the predominance of excitonic effects-mediated O2 activation for the production of 1O2 within the photocatalytic system. On the contrast, in the photo-synergetic H2O2 activation system, due to the strong adsorption of H2O2 on the atoms around Ov, the exciton dissociation process is accelerated and the enhanced charge transfer process is dominant, which effectively activates H2O2 to generate a large amount of •OH and O2•−. The present study provides valuable insights into the photocatalytic activation of H2O2 based on clay composites.

Investigation on chloride migration behavior of metakaolin-quartz-limestone blended cementitious materials with electrochemical impedance spectroscopy method

Calcined clay and limestone powder composites offer a viable solution for reducing carbon emissions in building materials by allowing significant cement replacement. However, there is a need for further investigation into their impact on durability, especially for low-grade clays. In this study, different ratios of metakaolin and quartz powder are utilized to simulate various grades of calcined clay, while limestone powder is incorporated as a partial cement substitute. Initially, the influence of metakaolin content on rapid chloride migration was analyzed. Subsequently, various analytical techniques such as free water content, Mercury Intrusion Porosimetry (MIP), X-ray diffraction (XRD)/Rietveld method, and electrochemical impedance spectroscopy (EIS) test were employed to investigate the effects of metakaolin contents on the pore structure, phase assemblage, and electrochemical parameters of the blended cementitious system. The relationship between chloride migration coefficient and free water content, critical pore size, and impedance parameters was established to determine the key indicators for chloride migration. The study revealed that systems with partial metakaolin content demonstrate improved chloride resistance in the blended system, which could be predicted using Rct1 from the EIS test. Furthermore, the inclusion of metakaolin and limestone powder facilitated the formation of Monocarboaluminate (Mc) and Hemicarboaluminate (Hc), leading to the refinement of the pore structure and inhibition of chloride transport within the blended material. This study indicates the potential of low-grade calcined clay to enhance the overall durability of the blended cementitious system while contributing to carbon emissions reduction.

Calcium Orthophosphate–Clay Composites—Preparation, Characterisation, and Applications: A Review

Calcium orthophosphates and clays and their composites are one of the most important groups in the field of new, modern, and technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This review provides a summary of recent research on calcium orthophosphate–clay composites, their preparation, characterisation, and use in various applications. An introduction to the subject is followed by a detailed description of the chemical and physical properties of calcium orthophosphates, clays, and clay minerals. This is followed by a general summary of preparation methods for calcium orthophosphate–clay composites. Particular attention is paid to the description of individual applications, i.e., environmental applications, biomaterials science (tissue engineering, pharmacology), and other emerging applications. Finally, future perspectives are summarised and discussed.

Electrochemical performance evaluation of a Ni/Fe mixed oxide natural clay composite as anode material for Li-ion batteries

A Ni/Fe mixed oxide natural clay composite was obtained by simple addition of bentonite natural clay sample after coprecipitation of layered double hydroxide (Ni0.75Fe0.25(OH)2(CO3)0.125) precursor; later this composite was sintered at 400 °C. The natural clay was collected from La Plata city (Argentina), and this has been used without further purification treatment. The electrochemical characterization allowed to identify stability improvement of the charge-discharge capacity values for the materials with calcination (35 % capacity retention after 60 cycles) against an anode prepared without clay (only 8 % retention). However, the anodic material without clay delivered a higher discharge capacity than the anode material with clay, as expected, due to the lacking the non-electroactive clay quantity. Physical characterization of the materials, such as nitrogen physisorption, showed a smaller particle diameter (37 nm against 54 nm) for the mixed oxides with and without natural clay, respectively. Despite this, by scanning electron microscopy a greater size difference was observed in the morphology for the oxide- natural clay composites. This could be because the smaller particle size along the interstitial space of the consecutive clay flakes and the pore volume of the material could be produced a synergistic effect between them; and thus promote a buffered volumetric expansion. This is generally reported to be responsible for the low charge- discharge cyclic performance observed in the conversion anodes. Also, the process of re-dissolution of the hydroxide precursor in the basic media, followed by the double hydroxide re-precipitation from Ni+2 and Fe+3 which are adsorbed in negative sites of the clay could be responsible for the achievement of the smaller size particles.

Preparation of Polyethylene Clay Composites via Melt Intercalation Using Hydrophobic and Superhydrophobic Organoclays and Comparison of Their Textural, Mechanical and Thermal Properties.

Polymer clay nanocomposites, which can exhibit many superior properties compared to virgin polymers, have gained increasing interest and importance in recent years. This study aimed to prepare composites of two organoclays with unusual ratios and different degrees of lyophilicity with low-density polyethylene and compare their textural structures and thermal and mechanical properties with those of virgin polymer. For this purpose, firstly, organoclays, hydrophobic and superhydrophobic organoclays (OC and SOC), were prepared by solution intercalation method using cetyltrimethylammonium bromide with and without addition of a hydrocarbon substance. Then, using both organoclays, polyethylene organoclay composites were prepared and characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Additionally, tensile and hardness tests were performed to determine the mechanical properties of the composites, and differential scanning calorimetry (DSC) thermograms were taken to examine their thermal behavior. XRD patterns and HRTEM images of hydrophobic and superhydrophobic organoclays and the composites show that the characteristic smectite peak of the clay shifts to the left and expands, that is, the interlayer space widens and, in the composites, it deforms immediately at low clay ratios. HRTEM images of the composites prepared especially with low clay ratios indicate that a heterogeneous dispersion of clay platelets occurs, indicating that nanocomposite formation has been achieved. On the contrary, in the composites prepared with high clay ratios, this dispersion behavior partially turns into aggregation. In the composites prepared using up to 20% by weight of superhydrophobic organoclay, extremely stable and continuous improvements in all mechanical properties were observed compared to those of the composites prepared using hydrophobic organoclay. This indicates that by using superhydrophobic organoclay, a ductile nanocomposite of polyethylene containing inorganic components in much higher than usual proportions can be prepared.

Aminated reduced graphene oxide-CuFe2O4 nanohybride adsorbent for efficient removal of imidacloprid pesticide.

To remove organic and inorganic agrochemicals from contaminated soil and water, adsorption has been regarded as a viable remediation approach. For the removal of organic pollutants, such as pesticides, cost-effective adsorbents have garnered a lot of interest. These include waste-derived materials, clay composites, metal-organic frameworks (MOFs), nanocomposites, and biochar-modified materials. In this study, copper ferrite (CuFe2O4) was prepared, characterized, and modified with aminated reduced graphene oxide (Am-rGO) to form a CuFe2O4/Am-rGO nanocomposite for the effective removal of imidacloprid (IMD) from water. The Langmuir isotherm model was used to determine the maximum adsorption capacity of the adsorbent (CuFe2O4/Am-rGO), which was estimated to be 13.1 (±1.5) mg g-1. At 0.5 mg L-1 IMD, the adsorbents were able to extract up to 97.8% of the IMD from the aqueous solution. The Freundlich model and the pseudo second-order model agreed well with the experimental data, proving that physisorption and chemosorption both played a role in the sorption process. CuFe2O4/Am-rGO nanocomposite offers high stability and improved reusability due to its improved removal efficiency. After five adsorption-desorption cycles, there was no appreciable reduction in elimination. Additionally, after adsorption tests, IMD can be easily removed after adsorption by an external magnetic field. These showed that Am-rGO had changed the surface of CuFe2O4 to make it easier for IMD to stick to it in aqueous solutions. When used adsorbent is co-processed with ethanol extraction and ultrasound cavitation, it can be regenerated and still work well as an adsorbent. Furthermore, CuFe2O4/Am-rGO demonstrated its environmental safety and ability to continue absorbing IMD across a variety of diverse matrices. As a result, this study demonstrates that CuFe2O4/Am-rGO is a long-lasting, easily prepared, and efficient adsorbent for the removal of IMD as one of the neonicotinoids.

(Invited) Clay: A Ubiquitous Sustainable Material for Energy Applications

Silicates and their precursors make up the majority of the land mass on Earth in the form of inorganic components of soil, silt, and sediment. Clay minerals, essentially hydrous silicates or aluminosilicates, are widely used in a variety of applications and industries, including ceramic goods, cement, drilling fluids, molding sands, anti-corrosion paints, paper manufacturing process, water treatment, polymer-clay composites for automotive industries, and even in medicine and pharmaceutical applications. Lately, it has found use in developing cost-effective ink, drug delivery, food packaging using oxygen barrier properties, and battery separators.Structure-property features of clays reveal that one can functionalize clays leveraging their porous structures, tunable surface areas, remarkable thermal and mechanical stabilities, and abundant reserves, which make clay one of the cheapest natural materials from a sustainable source and one of the most sought-after materials for a variety of applications. Clays generally have layered structures with the possibility of interchangeable intercalated ions and tunable chemical properties. They are composed of alternating tetrahedral silica (T) and octahedral alumina (O) sheets arranged in a 1:1 ratio (T-O). The tetrahedral sheets are formed from Si4+ ions coordinated with oxygen; however, the Al3+ metal ion is the central atom in the octahedral sheet. Bentonite or Montmorillonite is one of the most used clay minerals owing to its abundance and low cost. Notably, naturally occurring Bentonite has some octahedral sites occupied by the Mg2+ and Fe2+ ions. The presence of these ions allows tuning chemical properties and mechanical strength by functionalizing with organic molecules within the octahedral layers. Over the decades, polymer-based clay composites have been developed using this technique. Herein, we shed light on a new strategy to create hybrid clay films made from small organic molecules with charges at two ends, known as zwitter ions. Using this novel approach, we have developed cost-effective, environmentally benign, and biocompatible clay films with unique physical and chemical properties, where the clay galleries are infused with intercalating zwitter ions. The insertion of these ions increases the interlayer spacing while simultaneously allowing the formation of mechanically robust and thermally and chemically durable clay films. These hybrid clay films can be used as membranes and have been characterized using powder X-ray diffraction, X-ray photoelectron spectra, rheology, ATR-IR spectra, DSC-TGA, dynamic mechanical analyses, and imaging techniques. The effect of varying the carbon chain length and changing functional groups in these zwitter ion species has been verified to significantly impact the clay slurry's rheology and control the clay films' interlayer spacing. Electrochemical impedance spectroscopy studies of the hybrid films confirm that intercalation of zwitter ions in the clay structures leads to improved ionic conductivity of the clays. A series of impedance spectroscopy experiments conducted using various electrolytes reveal remarkable improvements in the ionic conductivity of the hybrid clay films. Contrary to metal ion batteries due to dendritic growth causing thermal degradation of the batteries, the hybrid clay films possess high thermal and mechanical stability that makes them versatile for energy materials. A cost-effective solution to engineering such hybrid films provides an efficient and recycle-free avenue to develop a new generation of materials from sustainable sources for energy applications, especially for battery separators and capacitors for the future.

Optimizing the thermophysical qualities of innovative clay–rGO composite bricks for sustainable applications

This work concerned the development of a unique reduced graphene oxide (rGO) nano-filler to provide innovative opportunities in enhancing the thermophysical performance of clay composite bricks. Whereas, a series of clay–rGO composite bricks were produced, doped with various levels of rGO nanosheets (i.e., 0, 1, 2, 4, and 6 wt% clay). Each clay–rGO composite’s microstructure, shrinkage, morphology, density, porosity, and thermophysical characteristics were carefully investigated, and the thermal conductivity performance was optimized. Incorporation of different levels of rGO NPs to the clay matrix allowed all the peaks intensity to rise relative to the untreated one in the XRD pattern. Meanwhile, the inclusion of these doping resulted in a grew in the crystallite sizes and apparent porosity within the compositions. In this vein, shrinkage fracture of fabricated brick composites varied depending on dopants type and levels during the drying and firing processes. Moreover, there are some changes in chemical compositions, as well as wave shifts, suggesting that functional groups of rGO may have contributed to partially introduce carbonyl groups in clay–rGO composites. Besides, the porous topography and bulk density improved rapidly with respect to the plane of the rGO nanosheets within the composites. The differ-dense microstructure displayed in the SEM micrographs supports these outcomes. Remarkably, clay–(4%)rGO compound not only has an optimum thermal conductivity value (0.43 W/mK), but it also has a high heat capacity (1.94 MJ/m3K). These results revealed the exceptional features of rGO sheets such as large surface area with high porosity within the modified clay composites.

Functionality and mechanistic parametric study of the potential of waste plantain peels and commercial bentonite for soybean oil refining

The consumption of unrefined vegetable oil poses acute and chronic health issues, yet improper disposal of waste plantain peels is not environmentally sustainable. This research investigates the feasibility, mechanism and thermodynamics of waste plantain peels, and commercial bentonite clay for soybean oil refining. Experiment was carried out using masses (1–4 g) of commercial bentonite clay, and unripe plantain peel ash (UPPA) to degummed and neutralized free fatty acid (FFA) contents in crude soybean oil at varying temperatures (50–120 °C), and time (15–35 min) for treatment of soybean oil. FTIR spectroscopy, SEM, and XRF techniques were applied to characterize the sample. The results established that at optimum 4.0 g dosage, the UPPA (97.73%) was more effective in the removal of FFA from oil at 50 °C and 20 min, while the clay (90%) was more effective in the removal of colour pigment from the vegetable oil 100 °C, and 25 min. The optimum efficiency of Clay-Ash-composite (70:30) in adsorbing pigment from soybean oil corresponds to 80%. The impact of changing viscosities, densities, and acid values on the performance of UPPA, clay, and clay-UPPA composite was investigated. Mechanistic studies confirmed the pseudo-second-order kinetics at 5 × 10–2 g/mg min−1 and 1.87 × 10–1 g/mg min−1, with corresponding adsorption capacity of 30.40 mg/g and 4.91 mg/g, at R2 ≤ 0.9982. The UPPA-driven sorption of FFA occurred as a physisorption and exothermic process (− 620.60 kJ/mol), while colour pigment removal occurred by chemisorption and endothermic process (22.40 kJ/mol). The finding recommends UPPA and composite as economically feasible for refining soybean oil.

Nano Magnesium Silicate Hydroxide as Synergistic Lubricant Additive With Micro Carbon Sphere for Enhanced Tribological Properties

Abstract In this study, the tribological properties of the mixture of nano magnesium silicate hydroxide (MSH) and micro carbon sphere (CS) are studied, and a superior synergistic anti-wear performance is exhibited under 600 N and 600 RPM. For determining the anti-wear mechanism, an easy two-step experimental method is innovatively used. It is proved that the decomposition of MSH is the key to exhibit the synergistic anti-wear effect with amorphous carbon (a-C). Results show that the H+ protons released by MSH decomposition can effectively convert Fe2O3 to Fe3O4 on worn surfaces. Besides, MSH also helps the formed a-C layer exist in low H content with stronger adhesion on the iron surface, and the detached H atoms from C–H further facilitate the reduction of Fe2O3. It is believed that the critical role of lamellate clay in synergy with a-C as a lubricant additive is determined, and a basis for the further anti-wear mechanism study of various a-C-modified clay composite is provided.

Hydroxyapatite–Clay Composite for Bone Tissue Engineering: Effective Utilization of Prawn Exoskeleton Biowaste

Hydroxyapatite (HA, Ca10(PO4)6(OH)2)-based porous scaffolds have been widely investigated in the last three decades. HA, with excellent biocompatibility and osteoconductivity, has made this material widely used in bone tissue engineering. To improve the mechano-biological properties of HA, the addition of clay to develop HA-based composite scaffolds has gained considerable interest from researchers. In this study, a cost-effective method to prepare a HA–clay composite was demonstrated via the mechanical mixing method, wherein kaolin was used because of its biocompatibility. Prawn (Fenneropenaeus indicus) exoskeleton biowaste was utilized as a raw source to synthesize pure HA using wet chemical synthesis. HA–clay composites were prepared by reinforcing HA with 10, 20, and 30 wt.% of kaolin via the mechanical mixing method. A series of characterization tools such as XRD, FTIR, Raman, and FESEM analysis confirmed the phases and characteristic structural and vibrations bonds along with the morphology of sintered bare HA, HA–kaolin clay composite, and kaolin alone, respectively. The HA–clay composite pellets, uniaxially pressed and sintered at 1100 °C for 2 h, were subjected to a compression test, and an enhancement in mechanical and physical properties, with the highest compressive strength of 35 MPa and a retained open porosity of 33%, was achieved in the HA–kaolin (20 wt.%) clay composite, in comparison with bare HA. The addition of 20% kaolin to HA enhanced its compressive strength by 33.7% and increased its open porosity by 19% when compared with bare HA. The reinforcement of HA with different amounts (10, 20, 30 wt.%) of kaolin could open up a new direction of preparing biocomposite scaffolds with enhanced mechanical properties, improved wear, and better cell proliferation in the field of bone tissue engineering.

Penerapan Teknologi Nanokomposit Pada Kemasan Pangan

Nanotechnology is the manipulation and use of materials and structures on the nanometer scale, roughly between 1 and 100 nm. Nanotechnology has invaded the agri-food industry, with many applications. Nanocomposite is one of the development technologies of Nanotechnology. Nanocomposite packaging is a polymer in which certain types of nano materials have been inserted, such as nano composite clay, nano silica particles (SiO2), carbon nanotubes, graphene, starch nanocrystals, cellulose-based nanofiber or nanowhiskers, chitin chitosan nanoparticles and other inorganics. This paper reviews the main applications of nanocomposites in the field of food packaging. The writing method used in writing this article review is a comparative writing method by collecting various sources obtained from several research journals from 2014 - 2021. From the results of this study, it was found that nanocomposites have very broad potential for their use as food packaging. Such as increasing antimicrobial ability, extending shelf life, maintaining color and sensory quality, as well as other benefits. However, it is necessary to carry out further identification regarding the nature of the interactions between nanoparticles and their effects on the food packaging application process.

Starch-Grafted Sodium Alginate-Modified Clay Composites as Environmentally Controlled-Release Materials for NPK Fertilizer

In an effort to mitigate the harm caused by the irregular use of agrochemicals, a safer release system using biopolymers is promising due to their availability, biodegradability, and eco-friendliness. Herein, controlled-release materials for NPK fertilizer were formulated using clay-based graft biopolymer composites. The clay soil sample was collected and classified through Skempton’s laboratory tests for soils and used as filler in starch-grafted sodium alginate (ST-g-SAG) with different percentages of clay. The clay-based graft biopolymer composites were synthesized via a microwave-assisted method. The biopolymer composites were characterized by FTIR, SEM, and EDS. The materials were loaded with NPK fertilizer, and a leaching test was conducted via a conductometric method to ascertain their release capacities. Biodegradation studies and the effect of humidity on the release of the NPK fertilizer were studied. Results of classification studies of the clay show Ca-montmorillonite (Ca-MMT) type. The average percent graft yield of starch-grafted sodium alginate/Ca-MMT (ST-g-SAG/Ca-MMT) was 83%. The results from FTIR and EDS showed that OH-, COO-, and CONH2 were responsible for the absorption of water. The release profile of the active NPK in the biocomposites ranged from 1% to 103%. Biodegradation results also showed a significant breakdown in biopolymer structure and mass loss. The release of active NPK from the material was humidity-responsive.

Adsorption, Modeling, Thermodynamic, and Kinetic Studies of Acteray Golden Removal from Polluted Water Using Sindh Clay and Quartz as Low-Cost Adsorbents

Due to growing environmental awareness and demands, many efforts were implemented for the transformation of waste materials into highly efficient adsorption capacity materials. In this work, efforts were made to convert the Sindh clay and quartz into an efficient composite for dye removal from polluted water. The synthesized composites were characterized using FT-IR, BET, SEM, and XRD. The synthesized composite showed a crystalline structure with specific characteristics, including a specific surface area of 7.20 m2/g and a pore diameter of 3.27 nm. The formation of iron cyanide hydrate (2030 cm−1) and iron oxides (418 cm−1) were depicted through Fourier transform infrared spectroscopy analysis. The micrographs obtained show that the unmodified quartz sample has a flattened and elongated shape compared to the modified quartz sample, which has aggregated and coarse morphology. The effects of several factors, such as temperature, contact time, and initial dye concentration, were studied. Kinetic models were also applied to determine the probable route of the adsorption process. For adsorption equilibrium analysis, the Dubinin–Radushkevich, Langmuir, Freundlich, Temkin, and Harkin–Juraisotherm models were employed. The Freundlich isotherm model and pseudo-first-order model best described the adsorption of dyes onto the clay composites. R2 values were close to 1 or more than 0.9, showing which equation fits the experimental data. The produced composite demonstrated good reusability, maintaining over 90% of the adsorption capacity after five reaction cycles without the need for reactivation.

Antifungal Properties of Nanosilver Clay Composites Against Fungal Pathogens of Agaricus bisporus

AbstractThis study aimed to determine the possible control of selected pathogenic and competitive fungi of A. bisporus by three nanosilver clay composites and establish the effective concentrations of the composites for inhibiting pathogens. Nanosilver (AgNPs) clay (zeolite, montmorillonite, and palygorskite) composites were synthesized by a microwave‐assisted surface functionalization technique, and various techniques characterized the products. Zeolite and montmorillonite composites showed uniformly distributed spherical AgNPs with an average size of 3.33 nm and 2.85 nm, respectively, whereas palygorskite presented agglomerated and unevenly distributed AgNPs. The influence of the various composites on 9 fungi, including strains of T. aggressivum f. aggressivum, L. fungicola, C. dendroides, and Mycogone sp., was determined in vitro at different concentrations. At 10 mg/mL, AgNP‐zeolite and AgNP‐montmorillonite inhibited 8 out of 9 pathogens, while AgNP‐palygorskite only inhibited 1 pathogen. The nanosilver clay composites tested against A. bisporus revealed no adverse effects on mycelial growth at any concentrations tested. This study confirms that AgNP‐zeolite and AgNP‐montmorillonite composites have effective antifungal properties and can be used as alternative fungicides against mushroom pathogens without affecting A. bisporus growth. However, further investigation is required to unravel the mechanism of selective antifungal activity observed in this study.

Copper Nanoparticles Doped on Polyvinyl Alcohol/Polymethyl Methacrylate/Montmorillonite (PVA-PMMA/MMT) as Ecofriendly Polymeric Hybrid Clay Composites: Study of their Bactericidal and Physical Properties

Copper Nanoparticles Doped on Polyvinyl Alcohol/Polymethyl Methacrylate/Montmorillonite (PVA-PMMA/MMT) as Ecofriendly Polymeric Hybrid Clay Composites: Study of their Bactericidal and Physical Properties

Improving the thermophysical aspects of innovative clay brick composites for sustainable development via TiO2 and rGO nanosheets

In the current work, distinctive nanoscale fillers, such as reduced graphene oxide (rGO) and titanium oxide (TiO2), were synthesized to open up novel opportunities to enhance the thermal performance of clay brick composites. Innovative clay-based nanocomposite bricks with various doping levels, including untreated clay, clay–rGO, clay–TiO2 and clay–rGO–TiO2, were synthesized for the first time to enhance brick's thermophysical performance. Physical observations of microstructure, shrinkage, morphology, density, porosity, as well as thermophysical characteristics of the composite clay bricks were investigated. Incorporating a varying quantity of rGO and TiO2 nanoparticles (NPs) into the clay matrix resulted in a variation in peak intensity within the lattice structure, along with a rise in the estimated crystallite size to 30.3 nm of clay–rGO–TiO2 composites. Meanwhile, the wealthy hydroxyl groups of TiO2 and rGO NPs boost the formation of many hydrogen bonds well distributed within clay structures, leading to rigid filler adherence. Moreover, the apparent porosity rose (i.e. from 24.01% to 43.64%) due to the creation of new intermolecular covalent bonds and hydrogen bonds between clay–H2O and metal oxides–OH groups. This porosity results in lighter bricks (i.e. bulk density decomposes from 2.02 to 1.41 g/cm3) with a pore size on the order of 3.5 µm. These variations are supported by the differ-dense microstructure presented in the SEM images. Interestingly, the Clay–rGO–TiO2 mixture not only has a high thermal conductivity value (0.44 W/mK), but also exhibits exceptional thermal diffusivity (4.1 mm2/S). The existence of TiO2 NPs, along with rGO nanosheets with a large surface area and high porosity features, which efficiently permits liquid absorption of the interlayers is the main explanation for these findings.

Eco-friendly unfired clay materials modified by natural polysaccharides

This study is devoted to the evaluation of the effect of natural polysaccharide (starch, alginate, and chitosan) solutions on the properties of clay composite. The authors describe the technology for obtaining gelated biopolymers (using hot and cold-water treatment and, acid treatment), as well as some characteristics of the obtained solutions, such as viscosity and pH. Some characteristics, such as bulk density, shrinkage, compressive strength, hygroscopic behavior, and water erosion resistance, are determined for the clay composites modified with biopolymer solutions. With increasing the concentration of biopolymer in solution, the bulk density and shrinkage values of the clay composite materials decrease. Also, the application of starch (2.5–10%) and alginate (2.5–7.5%) solutions has a positive effect on the compressive strength of the clay composite, with an increasing about 18–42%. Moreover, the addition of biopolymer solutions leads to an increase in the moisture adsorption degree of clay composites up to 34.2%. Finally, some biopolymers affect the structure and change the water erosion behaviour of clay composite.