Aerogel Microspheres Research Articles

Radiative cooling materials prepared by SiO2 aerogel microspheres@PVDF-HFP nanofilm for building cooling and thermal insulation

Radiative cooling is promising in meeting the current global demand for green sustainable development. However, the effective cooling of the existing radiant cooler will be limited due to the serious solar energy absorption and poor thermal insulation performance on the cold side. To addresss these issues, we propose herein a novel composite material of silicon dioxide (SiO2) aerogel microspheres combined with polyvinylidene fluoride-cohexafluoropropylene (PVDF-HFP) nanofiber membrane, in which SiO2 aerogel microspheres are firstly synthesized by sol-gel method and then incorporated into PVDF-HFP nanofiber membrane to give radiative cooling performance. As we expected, the molecular vibration characteristics of PVDF-HFP nanofiber membrane and the phonon polarization resonance of Si-O-Si bond in the transparent window can enhance the infrared emissivity of the membrane surface. In addition, the high porosity and the mesoporous structure formed by the interconnection of nano-network skeletons of SiO2 aerogel microspheres determine its excellent thermal insulation performance. The as-prepared material displays that the average solar reflectance of the composite membrane is 96.07 % and the average infrared emissivity of the atmospheric window is 94.95 %. Notably, when the average solar radiation intensity is 885.56 W•m−2, the passive radiative cooling temperature during the day can reach 11.2 °C. Furthermore, this material has excellent self-cleaning and thermal insulation performance, making it a potential radiant cooling candidate in many fields.

Foldable sandwich fabric-based composites with thermal insulation and low emissivity for highly efficient infrared stealth

Fabric-based infrared (IR) stealth composites with thermal insulation and low emissivity are desirable for improving IR camouflage of military targets and thermal management of special environments. Therefore, a flexible and foldable composite fabric with a sandwich structure is delicate designed in this work aiming to realize dual-modes IR effects. Polyester fabric chemically plated with copper-nickel (Cu/Ni@PF) and aluminum foil (AF) are on the top and bottom, respectively, acting as low emissivity layers. The medium layer is constructed by silica aerogel microspheres (SAM) with thickeners and waterborne polyurethanes (WPU) functioned as thermal insulation. The thermal conductivity of as-prepared composite fabric is only 0.05904 W/(m·K). When the AF is heated to 70 °C, the introduction of the SAM in the medium layer with the thickness of 300 μm makes Cu/Ni@PF as top surface exhibit a obvious temperature difference of 11.7 °C, demonstrating excellent thermal insulation. The AF maintains a low emissivity of less than 0.2, and the emissivity of Cu/Ni@PF was also as low as 0.296 at 8–14 μm, which can effectively shield the IR signal. Thanks to the Cu/Ni@PF as the top surface, the radiation temperature displays only 36.3 °C when heated at 70 °C, which meaning the dramatic IR signal strength reduce. Therefore, this dual-modes flexible and foldable composite can be a potential candidate in the IR stealth fields.

Miniaturized Hard Carbon Nanofiber Aerogels: From Multiscale Electromagnetic Response Manipulation to Integrated Multifunctional Absorbers

AbstractThe multiscale structural engineering strategy presents a powerful method for tailoring the structural attributes of materials at various levels, enabling the flexible control and manipulation of their electromagnetic properties. Nonetheless, orchestrating the multiscale architecture of polymer‐derived carbon aerogels specifically for microwave absorption poses significant challenges. Herein, aramid‐derived hard carbon nanofiber aerogel microspheres (CNFAMs) featuring a hierarchical skin‐core structure are fabricated through a wet‐spinning technique, combined with reprotonation‐mediated self‐assembly and carbonization processes. The presence of large‐scale voids between neighboring microspheres and the microscale porosity within the microspheres themselves improves impedance matching and promotes microwave reflection and scattering. The distinct graphitic domains and defects serve as pivotal elements for conduction and polarization losses, significantly impacting microwave attenuation. By meticulously tailoring the macroscale dimensions, microscale porous architecture, and nanoscale domains, the optimized CNFAMs demonstrate a remarkable absorption bandwidth of 9.62 GHz at an ultralow filling of 0.97 wt%. Additionally, the implementation of application‐oriented microwave absorption through the innovative integration of polysilsesquioxane‐CNFAMs in a host–guest aerogel is explored. This composite system brings together broadband absorption, superhydrophobicity, thermal insulation, resistance to freezing, and robust tolerance to harsh environments. Such a multifaceted approach is designed to tackle the growing challenges associated with complex electromagnetic environments effectively.

Carbon nanofiber aerogel microspheres with heterogeneous skin-core structure for broadband electromagnetic wave absorption

The advancement in the miniaturization of carbon aerogels into micro-sized spheres represents a significant development in the creation of ultralight, broadband microwave absorbers. Notwithstanding this innovation, there is still a considerable challenge in optimizing microwave absorption (MA) performance through heterointerface engineering within aerogel microspheres. Herein, we have developed skin-core heterogeneous aerogel microspheres by the in situ generation of ZIF-67 nanocrystals on the wet-spun aramid nanofiber (ANF) aerogel microspheres, followed by a high-temperature carbonization process. The resulting Co@C nanoparticle-enshrouded ANF-derived carbon nanofiber aerogel microspheres (Co@C/CNFAMs) demonstrate an exceptional equilibrium between impedance matching and multi-faceted attenuation. Remarkably, the Co@C/CNFAM2 sample attains a maximum effective absorption bandwidth of 8.72 GHz, while maintaining an ultralow filler proportion of 1.5 wt%. Moreover, the Co@C/CNFAM3 sample achieves a minimum reflection loss of −72.34 dB with a filling ratio of 1.2 wt%. Our findings offer a refined approach to the intricate engineering of heterostructures, along with the strategic macrostructural design, paving the way for the development of aerogel-based microwave absorbers that represent the next step in material science innovation.

Functionalized nano cellulose double-template imprinted aerogel microsphere for the targeted enrichment of taxanes

Paclitaxel, a diterpenoid isolated from the bark of Taxus wallichiana var. chinensis (Pilger) Florin, is currently showing significant therapeutic effects against a variety of cancers. Baccatin III (Bac) and 10-Deacetylbaccatin III (10-DAB) are in great demand as important precursors for the synthesis of paclitaxel. This work aims to develop a simple, rapid and highly selective, safe, and non-polluting molecularly imprinted material for 10-DAB and Bac enrichment. In this study, we innovatively prepared molecularly imprinted materials with nanocellulose aerogel microspheres and 2-vinylpyridine (2-VP) as a bifunctional monomer, and 10-DAB and Bac as bis-template molecules. In particular, functionalized nanocellulose dual-template molecularly imprinted aerogel microsphere (FNCAG-DMIM) were successfully synthesized by the bifunctional introduction of functional nanocellulose aerogel microsphere (FNCAG) modified with Polyethyleneimine (PEI) as a carrier and functional monomer, which provided a large number of recognition sites for bimodal molecules. FNCAG-DMIM showed high specificity for 10-DAB and Bac specific assays. Under the optimal experimental conditions, the adsorption capacities of FNCAG-DMIM for 10-DAB and Bac reached 52.27 mg g−1 and 53.81 mg g−1, respectively. In addition, it showed good reliability and practicality in the determination of real samples. The present study extends the research on the synthesis of natural functional monomers by molecularly imprinted materials and opens up new horizons for the targeted isolation of plant compounds by dual-template molecularly imprinted materials.

Chitosan aerogel loaded with biogenic palladium nanoparticles CH/Pd NPs exert antibacterial activity and wound addressing application in vitro and in vivo against bacterial skin infections

Bacterial skin infections that infect wounds and burns are considered one of the most serious medical problems that lead to delay wound healing, toxicity and even death. Therefore, there is an urgent need to develop an effective pharmaceutical material that promotes the treating of skin bacterial infections. Within this, we aimed in this study to synthesis and assess the effectiveness of novel chitosan/palladium nanoparticles (CH/Pd NPs) aerogel composites in treating bacterial skin infections and wound healing. Green method was employed for synthesis of Pd NPs using Allium sativum (A. sativum) extract, while crosslinking process and freeze-drying cycle were utilized for preparation of CH/Pd NPs aerogel composites. The prepared Pd NPs and CH/Pd NPs aerogel composite were thoroughly characterized using UV–vis, FTIR, XRD and SEM. The GC–MS analysis revealed that the main components in the A. sativum were diallyl disulfide (55.88 %) and diallyl trisulfide (24.34 %) which were among the four identified components. Additionally, the total phenols and flavonoids contents were 61.3 mg GAE/100 g and 18.8 mg QE/100 g, respectively. The swelling capacity of CH/Pd NPs aerogel microspheres reach 400 % with blood compatibility and slightly hemolysis ratio about 0.4 %. In vitro, the antibacterial studies demonstrated that loading Pd NPs with CH aerogel microspheres enhanced their effectiveness against MDR bacteria with complete inhibition for all bacterial strains growth. The CH/Pd NPs aerogel microspheres exhibited a significant inhibitory effect on biofilm formation. The biofilm inhibition percentage was found to be 87 % against the biofilm of S. aureus and 80 % against the biofilm of P. aeruginosa. In vivo infection model in rats, CH and CH/Pd NPs aerogel films stimulated skin tissue formation and healing wounds completely in 6 days with highly reduced in MDR and biofilm producing bacterial count. Finally, CH/Pd NPs aerogel composites represent a promising therapeutic strategy for the effective and enhanced healing of infected wounds.

Chitosan‐based aerogel microspheres for wastewater treatment

AbstractThis study aimed to present the effect of the mediums to dissolve chitosan on the morphology of obtained chitosan microspheres and find a suitable medium for preparing porous chitosan microspheres for adsorption application. Three acidic solutions, including acetic, ascorbic, and citric acids, were used to dissolve chitosan flakes. The prepared chitosan microspheres were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. The microspheres’ inner morphologies depended on the mediums to dissolve chitosan. The highest porosity of the chitosan microspheres was obtained using an acetic solution, while the sample showed the highest crystallinity prepared in a citric solution. Besides, the chitosan microspheres prepared in the acetic solution had the most efficient methylene blue (MB) removal from water. Its maximum MB sorption capacity was 79.37 mg g−1. The non‐linear pseudo‐second‐order kinetic model was the best kinetic fit for the interaction of MB with those chitosan microspheres. Moreover, the prepared microspheres showed good cyclic stability and easy recovery, suggesting their high feasibility in wastewater treatment.

Three-dimensional graded porous structure and compressible KGM-GO/CS/SA composite aerogel spheres for efficient adsorption of antibiotics

The abuse of antibiotics led to significant environmental pollution through persistent residues in water bodies, posing severe risks to both ecological systems and human health. Addressing this issue, recent studies highlighted the potential of carbonaceous materials as effective adsorbents for removing antibiotics from water. Despite the proven potential of various carbonaceous materials in water purification, the application of three-dimensional porous microspherical aerogels as adsorbents presented a promising yet comparatively less discussed avenue in the quest for efficient antibiotic removal from aquatic environments.This work introduced a novel KGM-GO/CS/SA composite aerogel sphere, developed via a simple sol–gel and dripping method, using konjac glucomannan (KGM) as a cross-linking agent. We extensively analyzed its adsorption efficiency against common antibiotics such as tetracycline (TC), ofloxacin (OFL), and sulfadiazine (SDZ), revealing its rapid adsorption kinetics and high capacity. The aerogel's micro-morphology, characterized by a graded porous structure with abundant microporous channels and a low bulk density of 21.2 mg/cm3, along with its enhanced mechanical properties and thermal stability due to KGM cross-linking, signified its potential as a robust adsorbent. The surface functional groups facilitated diverse interaction mechanisms, including electrostatic attraction, hydrogen bonding, and π-π interactions, contributing to the adsorbent's high performance. Furthermore, the surface charge of the aerogel varied with pH, enhancing its electrostatic adsorption capabilities. The adsorption behavior was best described by the quasi-second-order and Langmuir models, with maximum capacities of 427.63 mg/g for OFL, 374.35 mg/g for TC, and 231.09 mg/g for SDZ, thereby offering a promising solution for antibiotic pollution remediation and illustrating the utility of carbon-based aerogel microspheres in environmental applications.

Preparation and sustained release of diatomite incorporated and Eudragit L100 coated hydroxypropyl cellulose/chitosan aerogel microspheres

The drug encapsulation efficiency, release rate and time, sustained release, and stimulus-response of carriers are very important for drug delivery. However, these always cannot obtained for the carrier with a single component. To improve the comprehensive performance of chitosan-based carriers for 5-Fu delivery, diatomite-incorporated hydroxypropyl cellulose/chitosan (DE/HPC/CS) composite aerogel microspheres were fabricated for the release of 5-fluorouracil (5-Fu), and the release performance was regulated with the content of diatomite, pH value, and external coating material. Firstly, the 5-Fu loaded DE/HPC/CS composite aerogel microspheres and Eudragit L100 coated microspheres were prepared with cross-linking followed by freeze-drying, and characterized by SEM, EDS, FTIR, XRD, DSC, TG, and swelling. The obtained aerogel microspheres have a diameter of about 0.5 mm, the weight percentage of F and Si elements on the surface are 0.55 % and 0.78 % respectively. The glass transition temperature increased from 179 °C to 181 °C and 185 °C with the incorporation of DE and coating of Eudragit, and the equilibrium swelling percentage of DE/HPC/CS (1.5:3:2) carriers are 101.52 %, 45.27 %, 67.32 % at pH 1.2, 5.0, 7.4, respectively. Then, the effect of DE content on the drug loading efficiency of DE/HPC/CS@5-Fu was investigated, with the increase of DE content, the highest encapsulation efficiency was 82.6 %. Finally, the release behavior of DE incorporated and Eudragit L100 Coated microspheres were investigated under different pH values, and evaluated with four kinetic models. The results revealed that the release rate of 5-Fu decreased with the increase of DE content, sustained release with extending time and pH-responsive were observed for the Eudragit-coated aerogel microspheres.

Polyethylene glycol crosslinked modified chitosan/halloysite nanotube composite aerogel microspheres for efficient adsorption of melanoidin

Melanoidins are widely present in molasses wastewater and are dark-colored macromolecules that are hazardous to the environment. Currently, adsorption methods can effectively remove melanoidins from wastewater. However, existing adsorbents have shown unsatisfactory removal efficiency for melanoidins, making practical application challenging. Polyethylene glycol crosslinked modified chitosan/halloysite nanotube composite aerogel microspheres (PCAM@HNTs) were developed as a highly efficient adsorbent for melanoidins. The removal rate of PCAM@HNTs for melanoidins was 98.53 % at adsorbent dosage 0.4 mg/mL, pH 7, temperature 303 K and 450 mg/L initial melanoidins concentration, and the corresponding equilibrium adsorption capacity was 1108.49 mg/g. The analysis results indicate that the adsorption of melanoidins by PCAM@HNTs is a spontaneous and endothermic process. It fits well with pseudo-second-order kinetic models and the Freundlich isotherm equation. The adsorption of PCAM@HNT on melanoidins is primarily attributed to electrostatic and hydrogen bonding interactions. Furthermore, PCAM@HNTs exhibit excellent biocompatibility and are nonhazardous. Therefore, PCAM@HNTs proved to be an ideal adsorbent for the decolorization of molasses wastewater.

Engineering aramid nanofibers into robust macroscopic aerogel spheres for water purification

Aerogels are being developed for efficient removal of contaminants from water due to their high specific surface area and versatile surface chemistry. However, the formation of robust and chemical resistant aerogels is still challenging for practical implementation. Herein, the aramid nanofiber aerogel microspheres (ANFAMs) with dense skin and porous inner structures were fabricated on a large scale via the wet-spinning technique. The robust ANFAMs exhibit the ability to remove organic dye molecules with high efficiency in dynamic and harsh chemical environment. The visual study of weak interactions including electrostatic interactions, π-π interactions, and hydrogen bonding were revealed based on independent gradient model analysis. Moreover, one-step thermoinduced crosslinking enables the ANFAMs with superelasticity, which can maintain spherical after 500 compress-release cycles at 50% strain. The aerogel microspheres show excellent adsorption of various organic solvents with good reusability, paving the way to renewable adsorption for organic liquids from water. Therefore, this work provides a scalable and cost-effective production of robust aerogel microspheres toward the removal of the multiple water pollutants, and will guide future exploration on customizing high-performance enviromental remediation materials based on aramid nanofiber-based aerogels.

Collaborative electrospinning and ice-templating for sea urchin-inspired aerogel microsphere: Unraveling functional mechanisms in thermally conductive phase change composites

With the increased integration of electronic devices, effective heat management becomes imperative. Thermally conductive phase change composites play a vital role by efficiently conducting heat and utilizing matrix phase change for heat storage. Conventional materials encounter difficulties such as low thermal conductivity, restricted heat storage density, and vulnerability to leakage. This study presents a novel method combining electrospinning and ice-templating method to produce aerogel microspheres with sea urchin-like structures, resolving mentioned issues. The microspheres exhibit a radial microstructure and controllable size, serving as efficient fillers for the easy production of high-performance phase change materials. The microspheres are able to create an efficient interlocking mechanism with surface spike structures, forming a continuous thermal conduction and spatially confined network in the composite material. At a filler content of 43.9 vol%, the thermal conductivity of the Al aerogel microsphere/paraffin composite reaches a peak value of 3.2 W/mK, accompanied by a contact thermal resistance of 1.2 × 10−6 Km2/W. Subjecting the composite to elevated temperatures well above the matrix's phase change temperature preserves its structural stability. This work reports a new structured filler moulding method that supports the development of high performance thermally conductive phase change composites.

Adsorption of Levofloxacin onto Graphene Oxide/Chitosan Composite Aerogel Microspheres.

The removal of pharmaceutical residues from water resources using bio-based materials is very important for human safety and health. Bio-based graphene oxide/chitosan (GO/CS) aerogel microspheres were fabricated with emulsification and cross-linking, followed by freeze drying, and were used for the adsorption of levofloxacin (LOF). The obtained GO/CS aerogel microspheres were characterized with scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and thermogravimetry (TG). The effects of GO content, pH value, and temperature on their adsorption capacity were investigated. With the incorporation of 40 wt% GO, the adsorption capacity increased from 9.9 to 45.6 mg/g, and the highest adsorption capacity, 51.5 mg/g, was obtained at pH = 8 and T = 25 °C. In addition, to obtain deeper insight into the adsorption process, the thermodynamics and kinetics of the process were also investigated with four different models of LOF adsorption. The thermodynamic modeling results revealed that LOF adsorption is exothermic, and the kinetic investigation demonstrated that LOF adsorption is generally consistent with a pseudo-first-order rate law.

Enhanced properties of gelatin films incorporated with TiO2-loaded reduced graphene oxide aerogel microspheres for active food packaging applications

The synergistic effect of graphene sheets and titanium dioxide nanoparticles (TiO2) hybrid fillers can improve the antibacterial, mechanical, and barrier properties of gelatin (GL), making it more suitable to be used in the food packaging application. However, the uneven dispersion and aggregation of the hybrid fillers restrict its performance for further application. In order to achieve the above superior properties, reduced graphene oxide aerogel microspheres (rGOAMs) loaded with TiO2 (rGOAMs@TiO2) were successfully prepared using one-step hydrothermal process by reducing titanium sulfate into TiO2 on the framework of rGOAMs, followed by effective dispersion in the GL matrix to form nanocomposites (rGOAMs@TiO2/GL) through simultaneous ultrasonication and mechanical stirring, as well as an ultrasonic cell grinder process. Incorporating a mere 0.8 wt% of rGOAMs@TiO2 effectively improved the mechanical, antibacterial, UV light barrier, thermal stability, hydrophobicity, and water vapor barrier properties of the GL. Compared with the composites made of rGOAMs, TiO2, and GL (rGOAMs/TiO2/GL), rGOAMs@TiO2/GL composites showed stronger filler-matrix interactions, better filler dispersion, and lower TiO2 particle aggregation, suggesting superiority compared to rGOAMs/TiO2/GL composites at the same filler content. This innovative method of mixing GL with rGOAMs@TiO2 holds great promise for enhancing the suitability of GL in active food packaging applications.

Electromagnetic oscillation induced graphene-based aerogel microspheres with dual-chamber achieving high-performance broadband microwave absorption

Graphene-based aerogels have indeed generated significant interest in manufacturing microwave absorbers with ultra-low density and high efficiency. Nevertheless, unitary loss mechanism and impedance mismatch hinder corresponding application. Furthermore, it is essential to address the challenges related to structure control strategy and explanation of the loss mechanism. Dual-chamber graphene-based aerogel microspheres (AMs) with heterogeneous interfaces were fabricated through electrospinning-freeze drying and subsequent calcination. Significant differences are observed in reflecting and scattering of shell and dual-chamber structure against electromagnetic wave (EMW), enabling electromagnetic oscillation, sequential absorption and multi-level coupling of EMW. In addition, the dual-chamber construction is a pivotal role in optimizing impedance matching. In this regard, dual-chamber structure graphene-based AMs with 5 wt% loading were synthesized and exhibited excellent loss ability to EMW in the range of 5–18 GHz, which manifest −28.12 dB at 15.62 GHz, and accordingly, the fE is 6.0 GHz at 2.2 mm thickness, achieving full coverage dissipation of Ku-band. The results demonstrate that the dual-chamber graphene-based AMs achieve the effect of multi-frequency compatible and broadband microwave absorption at low thickness. The integration of the ideation of heterogeneous dual-chamber AMs with electromagnetic-oscillation and sequential loss provides a unique and innovative strategy for modulating lightweight and broadband efficiency absorbers.

Synthesis of hydrophilic sulfur-doped carbon aerogel microspheres and their mechanism of efficient removal of Sb(III) from aqueous solution

Antimony pollution is well recognized to induce cancer and deformity. By polymerization technique, a carbon aerogel microsphere (Ce@SCA) modified by Ce and S with micron size, well-developed pore structure, and large specific surface area was created. Ce@SCA exhibited the advantages of efficient selectivity and high adsorption capacity for Sb(III) in water. The highest adsorption capacity derived using the Sips isothermal model was 345.18 mg∙g−1, and the Sb (III) adsorption process was thermodynamically estimated as spontaneous, exothermic, and entropy-decreasing chemisorption. Meanwhile, Ce@SCA can convert highly toxic Sb(Ⅲ) into Sb(Ⅴ), which is suitable for the remediation of antimony-contaminated water bodies. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) were analyzed to elucidate the adsorption mechanism and to propose optimized adsorption configurations. A considerable number of –OH and -SH on the surface may increase the binding site of Sb, and the creation of S-Sb, O-Sb, and Ce-O-Sb covalent bonds was the key to Sb adsorption. This research provides a simple method for preparing cerium oxide-loaded and sulfur-doped carbon aerogel (Ce@SCA) with mild conditions and no hazardous waste, which also has superior adsorption properties for Sb (III) and high reusability.

Facile Synthesis of Polymer-Reinforced Silica Aerogel Microspheres as Robust, Hydrophobic and Recyclable Sorbents for Oil Removal from Water.

With the rapid development of industry and the acceleration of urbanization, oil pollution has caused serious damage to water, and its treatment has always been a research hotspot. Compared with traditional adsorption materials, aerogel has the advantages of light weight, large adsorption capacity and high selective adsorption, features that render it ideal as a high-performance sorbent for water treatment. The objective of this research was to develop novel hydrophobic polymer-reinforced silica aerogel microspheres (RSAMs) with water glass as the precursor, aminopropyltriethoxysilane as the modifier, and styrene as the crosslinker for oil removal from water. The effects of drying method and polymerization time on the structure and oil adsorption capacity were investigated. The drying method influenced the microstructure and pore structure in a noteworthy manner, and it also significantly depended on the polymerization time. More crosslinking time led to more volume shrinkage, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution and more compact network. Notably, the hydrophobicity increased with the increase in crosslinking time. After polymerization for 24 h, the RSAMs possessed the highest water contact angle of 126°. Owing to their excellent hydrophobicity, the RSAMs via supercritical CO2 drying exhibited significant oil and organic liquid adsorption capabilities ranging from 6.3 to 18.6 g/g, higher than their state-of-the-art counterparts. Moreover, their robust mechanical properties ensured excellent reusability and recyclability, allowing for multiple adsorption-desorption cycles without significant degradation in performance. The novel sorbent preparation method is facile and inspiring, and the resulting RSAMs are exceptional in capacity, efficiency, stability and regenerability.

Efficient adsorption and separation of norfloxacin from water by allophane aerogel microspheres

Norfloxacin contamination in the water environment has garnered international attention due to the dire risks it poses to ecosystems and public health. Aerogel can be easily extracted or separated from aqueous solutions, and it can be used for norfloxacin practical wastewater treatment. In this study, allophane and β-cyclodextrin were prepared as copolymers, and sodium alginate as a cross-linking agent to prepare allophane aerogel microspheres (A-M) for the efficient separation of norfloxacin in an aqueous environment. The A-M provides a highly three-dimensional porous structure, allowing norfloxacin to effectively penetrate the aerogels and enhancing their adsorption capacity. At pH = 7, the adsorption capacity of allophane microspheres on norfloxacin was 529 mg/g, which was 429 and 209 mg/g higher than that of β-cyclodextrin and allophane, respectively. Adsorption capacity after 5 regeneration cycles was 78.5% of the initial adsorbents. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis showed that the key adsorption mechanisms of A-M are surface complexation and hydrophobic interaction. Therefore, the prepared A-M materials are excellent adsorbents for the effective separation and removal of norfloxacin from the aquatic environment.

Electrostatic-spinning construction of HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres for tunable microwave absorption

Abstract Helical carbon nanotubes (HCNTs) are chiral materials that can form an induced magnetic field when current passes through them, making them a desirable material for absorbing microwaves. However, poor electrical properties and inert surfaces limit the application of HCNTs as sole materials. In this study, we develop HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres synthesized using an electrospinning-assisted ice template method. The modified surfaces of the HCNTs form hydrogen bonds with Ti3C2T x MXenes to produce hybrid aerogel microspheres. Because of the different functionalized surfaces of HCNTs (F-HCNTs), F-HCNTs@Ti3C2T x MXenes could be adjusted to obtain effective reflection loss (RL) of microwaves ranging from 2 to 18 GHz. The observed advantageous RL is attributed to the modified surface of the HCNTs, their porous structure, and the optimized impedance matching derived from the synergistic effect between HCNTs and Ti3C2T x MXenes. Successful assembly method for the 3D architectures of HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres significantly widens the practical applications of HCNTs in microwave absorption.

Ultrafine silica aerogels microspheres for adaptive thermal management in large-temperature-fluctuation environment

A large number of areas on earth is suffered from large-temperature fluctuation (LTF) during the days or over the seasons. However, current strategies for adaptive thermal management in the LTF environment are limited. In this study, we developed a simple and cost-effective strategy to synthesize ultrafine and nearly monodispersed silica aerogel microspheres (SAM) with an average diameter of 1.9 μm. The aerogels possess low thermal conductivity of 0.039 W·m−1·K−1 and can preserve heat by reducing heat dissipation in cold environments. Meanwhile, IR emissivities range from 0.13 to 0.98 and a relatively high solar reflectance of 0.65, leading to an impressive sub-ambient cooling of 9.1 °C in a hot daytime. Additionally, a theoretical carbon emission analysis of the aerogels' daytime cooling and night warming suggests a carbon emission reduction of 13.6 tCO2 eq. This study develops a strategy to synthesize ultrafine SAM and provides a strategy for passive cooling and passive warming by SAM with the combination of passive cooling and thermal insulation, which could help to achieve global carbon neutrality and sustainability, and solve the problems of thermal management with large temperature-fluctuation.