Search Results (286)

In this study, the influences of natural fibres (sugarcane bagasse (SB) and sawdust (SD)) on the material properties of polybutylene succinate (PBS) prepared through melt compounding were investigated. The study further evaluated the effects of incorporating halloysite nanotubes (HS) and expandable graphite (EG) on the properties of PBS/SD and PBS/SB binary and PBS/SB/SD hybrid composites. The morphological analysis indicated poor interfacial adhesion between PBS and the fibres. The obtained findings indicated enhancements in the complex viscosity of PBS in the presence of natural fibres, and further improvements in the presence of HS and EG. The stiffness of PBS hybrid composites also increased upon the addition of HS and EG. Moreover, the crystallization temperatures of PBS increased in the presence of fillers, with EG showing better nucleation efficiency. However, the mechanical properties (toughness and impact resilience) decreased due to the increased stiffness of the composites and the poor interfacial adhesion between the matrix and the fillers, indicating the need to pre-treat the fibres to enhance compatibility. Overall, the material properties of PBS/SD/SB hybrid composites were enhanced by incorporating HS and EG at low concentrations. Full article

Halloysite nanotubes, a naturally occurring nanomaterial with a unique tubular morphology, have shown considerable potential for heavy metal remediation. However, significant inconsistencies in the reported maximum adsorption capacities (q_max) for heavy metal ions—such as Pb²⁺, which ranges from 7.5 to 84.0 mg/g with a coefficient of variation (CV) of 68%—have severely hindered both scientific understanding and practical application of this promising material. To address this critical knowledge gap, we conducted a reassessment using carefully selected halloysite specimens from three geologically distinct deposits (Utah, USA; Henan and Yunnan, China). Under rigorously controlled experimental conditions, we precisely quantified the adsorption capacities of halloysite for Cd²⁺, Zn²⁺, and Pb²⁺. Through an integrated multi-technique characterization approach involving XRF, XRD, FTIR, TEM, and BET analyses, we identified two fundamental crystallochemical parameters that govern the adsorption performance of halloysite: the degree of lattice substitution and the density of surface hydroxyl groups. Our findings reveal that optimal heavy metal adsorption occurs in halloysite with lower lattice substitution and higher surface hydroxyl density. This work not only provides a reliable range of adsorption capacities for halloysite but, more importantly, establishes a scientific foundation for optimizing the application of halloysite in heavy metal remediation. Full article

The aim of this research was to compare the growth-inhibitory effect of halloysite-based nanotubes preloaded with sodium fluoride incorporated into two commercial glass ionomers (Vitrebond 3M^TM and Ionobond VOCO) for indirect pulp capping. Methods: Sixty samples were prepared and were distributed into two control groups, two positive control groups and two experimental groups. A total of 10% of the total weight of ionomer powder required to prepare each sample was replaced with nanotubes that had been preloaded at 2000 parts per million (minimum inhibitory dose for Streptococcus mutans established in this study using the McFarland index). The growth-inhibitory effect was determined by placing the samples in Petri dishes inoculated with S. mutans for 24 h at 37 °C. Results: Regarding the control groups, only Vitrebond demonstrated a growth inhibition zone; both experimental groups showed an inhibitory effect, and statistical differences were observed when the experimental Ionobond group and control groups were compared. Conclusions: The ionomers reinforced with fluorine-modified nanotubes showed an adequate inhibitory effect on Streptococcus mutans. Full article

Supported Pd-based catalysts have been widely applied in the hydrogenation of specific functional groups. Recent trends have focused on employing Pd-based heterogeneous catalysts supported on inorganic nanotubes, wherein inner surface functionalization modulates both palladium nanoparticle (Pd-NP) dispersion and the interaction between reactants and the catalyst surface, thereby influencing catalytic properties. This study aims to develop a catalytic system using amine-lumened halloysite nanotubes immobilizing Pd-NPs (Pd/HNTA) as catalysts for hydrogenation reactions. The formation of Pd-NPs within the organo-functionalized lumen—modified by 3-aminopropyltrimethoxysilane—is confirmed by transmission electron microscopy (TEM) imaging, which reveals a particle size of 2.2 ± 0.4 nm. For comparison, Pd-NPs supported on pristine halloysite (Pd/HNTP) were used as control catalysts, displaying a metal particle size of 2.8 ± 0.8 nm and thereby demonstrating the effect of organic functionalization on the halloysite nanotubes. Both catalysts were employed in the hydrogenation of furfural (FUR) and nitrobenzene (NB) as model reactions. Pd/HNTA demonstrated superior catalytic performance for both substrates, with TOF values of 880 h⁻¹ for FUR and 946 h⁻¹ for NB, and selectivities exceeding 98% for tetrahydrofurfuryl alcohol (THFOH) and aniline (AN), respectively. However, recyclability studies displayed that Pd/HNTA was deactivated at the 10 catalytic cycles during the hydrogenation of FUR, whereas, in the hydrogenation of NB, 5 catalytic cycles were achieved with maximum conversion and selectivity at 360 min. These results revealed that the liquid-phase environment plays a pivotal role in catalyst stability. In the hydrogenation of NB, the coproduction of H₂O adversely affects the interaction between the Pd particles and the inner amine-modified surface, increasing the deactivation of the catalyst with reuse. Thus, the Pd/HNTA catalyst holds significant promise for the development of noble-metal-based catalysts and their application in the transformation of other reducible organic functional groups via hydrogenation reaction. Full article

The subject of the conducted study was primarily focused on the development of a new type of polymer blend modified with the use of nanosized fillers. The research concept involved the use of polycarbonate/polyethylene terephthalate glycol (PETG/PC) blends modified with the EBA-GMA impact modifier (ethylene–butylene–acrylonitrile copolymer) and three different types of nanofillers: montmorillonite (MMT), halloysite (HNT), and carbon nanotubes (CNT) of two types. The combination of PC, PETG, and EBA phases was used in order to achieve enhanced mechanical performance and stable processing properties. The results of the conducted study revealed that for the toughened PETG/PC/EBA blends, the impact resistance was strongly improved from the reference by 1.5 kJ/m² to 15 kJ/m². However, the results for the nanocomposites revealed that the MMT and HNT additions were limiting the impact strength. In contrast, the Charpy test results for CNT were again close to 15 kJ/m². The results of the thermal resistance measurements again revealed more favorable properties for CNT-modified PETG/PC/EBA blends. Full article

The rapid advancement of sustainable materials has driven the need for high-performance polymer nanocomposites with superior mechanical, thermal, and structural properties. In this study, a novel RPET/PA-11/Joncryl^® nanocomposite reinforced with halloysite nanotubes (HNTs) is developed for the first time, marking a significant breakthrough in polymer engineering. Six different proportions of HNT (0, 1, 2, 3, 4, and 5 phr) are introduced to the blend of rPET/PA-11/Joncryl^® through a twin-screw extruder and injection moulding machine. The incorporation of HNTs into the RPET/PA-11 matrix, coupled with Joncryl^® as a compatibilizer, results in a synergistic enhancement of material properties through improved interfacial adhesion, load transfer efficiency, and nanoscale reinforcement. Comprehensive characterization reveals that the optimal formulation with 2 phr HNT (NCS-H2) achieves remarkable improvements in tensile strength (56.14 MPa), flexural strength (68.34 MPa), and Young’s modulus (895 MPa), far exceeding conventional polymer blends. Impact resistance reaches 243.46 J/m, demonstrating exceptional energy absorption and fracture toughness. Thermal analysis confirms enhanced stability, with an onset degradation temperature of 370 °C, attributing the improvement to effective matrix–filler interactions and restricted chain mobility. Morphological analysis through FESEM validates uniform HNT dispersion at optimal loading, eliminating agglomeration-induced stress concentrators and reinforcing the polymer network. The pioneering integration of HNT into RPET/PA-11/Joncryl^® nanocomposites not only bridges a critical gap in sustainable polymers but also establishes a new benchmark for polymer nanocomposites. This work presents an eco-friendly solution for engineering applications, offering mechanical robustness, thermal stability, and recyclability. The results form the basis for next-generation high-performance materials for industrial use in automotive, aerospace, and high-strength structural applications. Full article

The wastewater from Chemical Mechanical Polishing (CMP) generated in the semiconductor industry contains a significant concentration of suspended particles and necessitates rigorous treatment to meet environmental standards. Ceramic ultrafiltration membranes offer significant advantages in treating such high-solid wastewater, including a high separation efficiency, environmental friendliness, and straightforward cleaning and maintenance. However, the preparation of high-precision ceramic ultrafiltration membranes with a smaller pore size (usually <20 nm) is very complicated, requiring the repeated construction of transition layers, which not only increases the time and economic costs of manufacturing but also leads to an elevated transport resistance. In this work, halloysite nanotubes (HNTs), characterized by their high aspect ratio and lumen structure, were utilized to create a high-porosity transition layer using a spray-coating technique, onto which a γ-Al₂O₃ ultrafiltration selective layer was subsequently coated. Compared to the conventional α-Al₂O₃ transition multilayers, the HNTs-derived transition layer not only had an improved porosity but also had a reduced pore size. As such, this strategy tended to simplify the preparation process for the ceramic membranes while reducing the transport resistance. The resulting high-flux γ-Al₂O₃ ultrafiltration membranes were used for the high-efficiency treatment of CMP wastewater, and the fouling behaviors were investigated. As expected, the HNTs-mediated γ-Al₂O₃ ultrafiltration membranes exhibited excellent water flux (126 LMH) and high rejection (99.4%) of inorganic particles in different solvent systems. In addition, such membranes demonstrated good operation stability and regeneration performance, showing promise for their application in the high-efficiency treatment of CMP wastewater in the semiconductor industry. Full article

To extend food shelf life and reduce plastic pollution, halloysite nanotubes (HNTs) were employed as a carrier to load cinnamon essential oils (CEOs), and the nanotubes were blended with polybutylene adipate co-terephthalate (PBAT) resin to fabricate the film with non-contact antimicrobial activity. The results showed that the HNTs had a high loading efficiency (about 11%) for CEOs. The retention rate of CEOs in HNTs was still 33% after twenty days later, which indicated that the CEOs/HNTs nanoparticles had a long-acting controlled-released effect. The composite films represented excellent mechanical properties and antibacterial effects against Staphylococcus aureus and Escherichia coli due to the non-contact antimicrobial activity of CEOs. The strawberries remained fresh after five days when the composite film was applied in the packaging of strawberries, which proves that composite films can extend the shelf life of food. Therefore, it has potential application prospects in the food industry. Full article

This study presents a sustainable strategy to enhance polymer encapsulation, adsorption, and functional properties by chemically modifying sodium alginate with hydrophobic groups. Hydrophobic alginate derivatives were synthesized via a solvent-free method using hexadecyl trimethylammonium bromide, resulting in nanoparticles capable of effectively capturing non-polar compounds. To further improve compatibility within alginate-based biocomposites, halloysite nanotubes were modified through ball milling and surfactant-assisted treatments. The resulting nanocomposites (MBHA and MHHA) exhibited significantly enhanced adsorption and controlled release behavior, as confirmed by FTIR analysis of hexadecyl alginate ester conjugation. Vitamin D₃ adsorption followed the Langmuir isotherm, with high correlation coefficients (R² = 0.998 for MBHA and R² = 0.991 for MHHA), indicating monolayer adsorption on a homogenous surface. Kinetic modeling revealed that the adsorption process adhered to a pseudo-second-order model (R² = 0.9969 for MBHA and R² = 0.999 for MHHA), suggesting that chemisorption was the dominant rate-controlling mechanism. These results demonstrate the critical role of surface modification in designing nano-engineered biopolymers with superior adsorption, stability, and release profiles, offering sustainable applications in medicine, agriculture, and environmental remediation. Full article

Sustainable strategies are required to mitigate elevated atmospheric CO₂ levels. Achieving that by adsorption, especially by using clay-based adsorbents, drew attention. These are even more promising when these adsorbents are obtained by low-cost modifications. This study evaluates the effect of ball milling on the carbon capture performance of Australian halloysite nanotube (HNT)-rich kaolin samples: one without iron impurities (Hal) and the other with iron impurities (HalFe). The iron was mainly nested within illite/mica minerals in HalFe. Samples were ball-milled for 30 and 60 min, and their CO₂ sorption was assessed at various pressures and temperatures. Crystallography, electronic microscopy, and surface area and charge characterization revealed reduced length and increased width of tubular structure following ball milling, leading to higher specific surface area without compromising crystallinity. CO₂ sorption of Hal increased 14% at 20 bar and 15 °C after 60 min milling, with a ~300% rise at near-atmospheric pressures. Conversely, milling negatively affected CO₂ sorption of HalFe, likely due to iron/illite-mica-related damage during milling. Crystallography, infrared, and thermographic analyses revealed physisorption as the primary sorption mechanism. Since direct disposal of CO₂-laden materials is against sustainability principles, these materials were tested for methylene blue removal from aqueous solutions, achieving ~83% (Hal) and ~91% (HalFe) removal efficiencies. This highlights HNTs-rich kaolin clays’ valorization potential for carbon capture and utilization (CCU). Full article

Lidocaine is an analgesic agent frequently incorporated in topical formulations intended for application in minor surgical procedures or relieving neuropathic pain associated with numerous conditions, including post-herpetic neuralgia or diabetic peripheral neuropathy. In this study, Pickering o/w emulsions with halloysite nanotubes as a stabilizing agent and lidocaine incorporated in the internal phase were formulated with the use of the Quality by Design (QbD) approach. The selected emulsions were transformed into semisolid gels with poloxamer 407 as a thickening agent, and investigated for rheological and textural properties, indicating the mechanical features of the obtained gels. Moreover, the obtained formulations were tested for lidocaine release with the use of vertical Franz diffusion cells in order to assess the relationship between the applied composition and potential clinical applicability of the analyzed gels. The obtained results indicate that the emulsion droplet diameter is affected mostly by the oil and halloysite contents. The yield stress points, hardness and cohesiveness values of the obtained gels increased with the oil content. The drug release rate seems to be affected mostly by the concentration of the active ingredient in the oil phase. Full article

In multi-layered wood materials, varying rates of dimensional changes can easily lead to cracking, which can have a negative impact on their structure and functionality. This study focuses on cracking issues of decorated blockboard caused by moisture content changes. First, surface cracks on the decorated blockboard were observed and classified using optical microscopy and scanning electron microscopy (SEM). Second, from modeling perspectives, the critical tensile strength of the surface of the decorated blockboard was predicted to be 16.93 MPa, providing guidance for crack-resistant modification. Subsequently, halloysite nanotubes (HNTs) were incorporated into MF-resin-impregnated paper, achieving a Grade 5 crack resistance for decorated blockboard. The interaction between HNTs and MF resin forms a multiscale stress–dispersion system, as confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), indicating hydrogen and covalent bonding between HNTs and the MF resin. With a 5% HNTs addition, the tensile strength and strain break of the MF-resin-impregnated paper reached 36.60 MPa and 1.12%, respectively, representing increases of 97.39% and 60.00%, respectively, effectively preventing surface cracking. This has significant implications for improving the durability and performance of decorated blockboard in practical applications. Full article

The application of electrospinning technologies for the preparation of mats based on mucoadhesive polysaccharides, such as chitosan (CS), is an attractive strategy for the development of biopolymeric delivery systems for topical corticosteroids. In this work, an electrospinning technique is described for the preparation of CS-based mats doped with halloysite nanotubes (HNTs) with modified release of clobetasol propionate (CP). The optimized composition of the electrospinning solution was determined: 2.4% solution of CS in 46% acetic acid with addition of PEO (10% of CS mass) and HNTs (5% of CS mass); CP was introduced as an ethanol solution at the rate of 2 mg CP per 1 g of the obtained nonwoven material. The process parameters (the electrospinning voltage of 50–65 kV, the rotation speed of the spinning electrode of 10 min⁻¹, and the distance between the electrodes of 24 cm) were also optimized. The developed technology allowed us to obtain homogeneous nanofiber mats with excellent mechanical properties and biphasic drug release patterns (66% of CP released within 0.5 h and 88% of CP released within 6 h). The obtained nanofiber mats maintained the anti-inflammatory activity of corticosteroid at the level of free CP and showed no cytotoxicity. Full article

The human body is known as a responsive healing machine, but sometimes, broken bones do not heal, especially if a bacterial infection is present. The present study describes the fabrication and characterization of a nanocomposite hydrogel patch incorporated with silicon nitride and magnesium oxide (MgO) deposited on the halloysite nanotube (HNT) surface using a facile and inexpensive electrodeposition coating process. Scanning electron microscopy (SEM) was used to observe the surface morphology of the MgO/HNT surface coating and the nanocomposite patch. Material characterization, including SEM, contact angle, pore size analysis, and tensile properties, was performed to determine the composite’s structure and material properties. E. coli and S. aureus bacterial cultures were used to test the antimicrobial properties. Cellular response to MgO/HNTs was studied using mouse embryonic fibroblasts. The nanocomposite hydrogel patch was discovered to possess inherent properties when tested against bacterial cultures, and it was found to enhance fibroblast cell migration and proliferation. The nanocomposite hydrogel patch also showed sustained drug release. Materials involved in the fabrication helped in the swelling properties by which the nanocomposite hydrogel patch has approximately 400% of its initial weight discovered during the swelling test. Full article

The issue of gas permeability of porous beds is important for the development of a new generation of clean energy sources, especially in the context of unconventional energy storage. Detailed experimental studies were carried out to demonstrate the gas permeability of porous materials: in situ karbonizat and natural and synthetic pumice. The measure of gas permeability was the volumetric gas flow velocity resulting from the permissible pressure difference forcing the gas flow in a given axis (X, Y, Z) on a sample of a cube-shaped porous material. A novelty is the indication of correlation with selected materials exhibiting features of unconventional energy storage. Assessment of the gas permeability coefficient for selected material features shows an increasing trend for epoxy resin, dacite, in situ carbonizate and pumice. On the other hand, for carbonate rocks, mudstones and shales, there is a decrease in gas permeability. The indicated porous materials can be storage tanks of unconventional energy carriers. In an innovative way, a material (halloysite) was indicated that has the ability to store and be a source of transport in the form of a cylindrical model (nanotube) for future implementation of isotropic features of porous materials. Full article