Search Results (297)

Atmospheric water harvesting (AWH) offers a decentralized and renewable solution to global freshwater scarcity. Bio-derived and hybrid aerogels, characterized by ultra-high porosity and hierarchical pore structures, show significant potential for high water uptake and energy-efficient, low-temperature regeneration. This PRISMA-guided systematic review synthesizes evidence on silica, carbon, MOF-integrated, and bio-polymer aerogels, emphasizing green synthesis and circular design. Our analysis shows that reported water uptake reaches up to 0.32 g·g⁻¹ at 25% relative humidity (RH) and 3.5 g·g⁻¹ at 90% RH under static laboratory conditions. Testing protocols vary significantly across studies, and dynamic testing typically reduces these values by 20–30%. Ambient-pressure drying and solar-photothermal integration enhance sustainability, but performance remains highly dependent on device architecture and thermal management. Techno-economic models estimate water costs from USD 0.05 to 0.40 per liter based on heterogeneous assumptions and system boundaries. However, long-term durability and real-world environmental stressor data are severely underreported. Bridging these gaps is essential to move from lab-scale promise to scalable, commercially viable deployment. We propose a strategic roadmap toward 2035, highlighting the need for improved material stability, standardized testing protocols, and comprehensive life cycle assessments to ensure the global viability of green aerogel technologies. Full article

Hydrophobic phenolic/silica hybrid aerogels were synthesized via different methyl modification methods including in situ polymerization (RA-IS), surface grafting (RA-SG), and vapor deposition (RA-VD). All the methods achieved good hydrophobicity, with a water contact angle around 140°, and the hydrophobic mechanisms were clarified. RA-IS possesses the highest specific surface area and nanopore volume, and the lowest bulk density. Therefore, it exhibits much lower thermal conductivity (32.2 mW·m⁻¹·K⁻¹) at 25 °C than RA-SG, RA-VD and other reported phenolic/silica hybrid aerogels. The compression strength (3.3 MPa) and Young’s modulus (19.2 MPa) of RA-IS are higher than those of its state-of-the-art counterparts. The methyl groups in RA-IS are linked in the matrix by a covalent bond, leading to excellent weather resistance under thermal, hygrothermal, and ultraviolet aging conditions. The methyl species in RA-SG and RA-VD are loaded on the surface via a covalent bond and physical adsorption, exhibiting poor weather resistance. RA-IS is incombustible and its microstructure is stable on an alcohol flame. This study provides new insights into the hydrophobicity of phenolic/silica hybrid aerogels, and offers significant guidance for developing aerogels with high strength, hydrophobicity, flame resistance, weather resistance, and insulation performance for building insulation. Full article

Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO₂–ZrO₂–phenolic resin aerogels (SZPA). First, nano-silica sol and nanometer-scale zirconia were physically blended to form a uniformly dispersed mixture. Subsequently, the modified silica was incorporated into a phenolic resin solution to construct a three-dimensional hybrid silica–phenolic network framework. Nano-sized zirconia was then uniformly dispersed within the matrix as a physical reinforcing phase through high-shear dispersion. Finally, the SZPA with a hierarchical nanoporous structure was obtained via ambient-pressure drying. Owing to its unique hybrid network structure, the aerogel exhibits markedly improved properties: the thermal conductivity is as low as 0.0419–0.0431 W/(m·K) (a reduction of approximately 24%), and the specific surface area is as high as 190–232 m²/g (an increase of approximately 83%). Meanwhile, the inorganic network considerably enhances the residual mass at elevated temperatures, as well as the oxidation resistance and thermal stability of the matrix. Among the tested materials, the SZPA-4 exhibited outstanding thermal insulation capability at high temperatures; its back surface temperature reached only 74.4 °C after 600 s of exposure to a 1200 °C butane flame. This study provides a feasible route for the preparation of high-performance phenolic-based composite aerogels for aerospace thermal protection systems, thereby expanding their potential applications in extreme thermal environments. Full article

With the advancement of new power systems, phase-change materials (PCMs), owing to their ability to convert and store electrical energy, are increasingly recognized as a key solution to the intermittency of power supply. Nevertheless, such materials face challenges, including leakage and low thermal conductivity, which lead to reduced utilization efficiency. In this study, guar gum was used as the macroscopic framework, while self-prepared and optimized silica aerogel microsheets served as the microscopic framework to synergistically encapsulate the polyethylene glycol (PEG). Titanium dioxide (TiO₂) nanoparticles were incorporated to improve overall thermal conductivity, resulting in the composite PCM, GTS-PEG. In-depth characterization demonstrated effective PEG retention within the matrix, with a melting heat storage density of 164.16 J/g. Upon 30 min of continuous heating at 90 °C, the mass loss remained as low as 4.83%, indicating excellent thermal stability. The addition of TiO₂ increased thermal conductivity to 0.53 W/(m·K), representing a 140% boost over unmodified material. As a result, GTS-PEG not only successfully overcomes the leakage and thermal conductivity limitations of conventional PCMs but also, as a green and low-carbon innovative solution, paves a new path for the coordinated optimization and efficient conversion of power grid energy systems. Full article

A sustainable pathway for converting low-value solid waste (Coal gangue, CG) into high-performance thermal insulation materials through a green synthesis strategy has been demonstrated. The SiO₂ was successfully and efficiently extracted from CG in the form of sodium silicate. The subsequent sol–gel process of sodium silicate solution utilized an innovative CO₂ carbonation method, which replaced the conventional use of strong acids, thereby reducing the carbon footprint and enhancing process safety. Hydrophobic SiO₂ aerogel was subsequently prepared via ambient pressure drying, exhibiting a high specific surface area of 750.4 m²/g, a narrow pore size distribution ranging from 2 to 15 nm and a low thermal conductivity of 0.022 W·m⁻¹·K⁻¹. Furthermore, the powdered aerogel was shaped into a monolithic form using a simple molding technique, which conferred appreciable compressibility and resilience, maintaining the low thermal conductivity and hydrophobicity of the original aerogels, ensuring its functional integrity for practical applications. Practical thermal management tests including low and high temperature, conclusively demonstrated the superior performance of the prepared aerogel material. This work presents a viable and efficient waste-to-resource pathway for producing high-performance thermal insulation materials. Full article

In this work, we present a novel compact particle identification (PID) detector concept based on Silicon Photomultipliers (SiPMs) optimized to perform combined Ring-Imaging Cherenkov (RICH) and Time-of-Flight (TOF) measurements using a common photodetector layer. The system consists of a Cherenkov radiator layer separated from a photosensitive surface equipped with SiPMs by an expansion gap. A thin glass slab, acting as a second Cherenkov radiator, is coupled to the SiPMs to perform Cherenkov-based charged particle timing measurements. We assembled a small-scale prototype instrumented with various Hamamatsu SiPM array sensors with pixel pitches ranging from 2 to 3 mm and coupled with 1 mm thick fused silica window. The RICH radiator consisted of a 2 cm thick aerogel tile with a refractive index of 1.03 at 400 nm. The prototype was successfully tested in beam test campaigns at the CERN PS T10 beam line with pions and protons. We measured a single-hit angular resolution of about 4 mrad at the Cherenkov angle saturation value and a time resolution better than 50 ps RMS for charged particles with Z = 1. The present technology makes the proposed SiPM-based PID system particularly attractive for space applications due to the limited detector volumes available. In this work, we present beam test results obtained with the detector prototype and we discuss possible configurations optimized for the identification of ions in space applications. Full article

Energy-efficient buildings require materials with low thermal conductivity, and high fire resistance and mechanical properties. Traditional chitosan aerogel is limited by its poor fire resistance and silica aerogel is either brittle or displays a high thermal conductivity. Herein, we report a dual-modified aerogel with high mechanical properties, low thermal conductivity, and excellent fire resistance. Briefly, the chitosan-derived silica aerogel (CA) was first fabricated, followed by loading varying contents of phytate-piperazine (PPA) intumescent flame-retardant. This well-designed aerogel (CA/PPA) combines with the high mechanical strength of chitosan aerogel, the excellent fire resistance function of silica aerogel, and the intumescent flame-retardant performance of PPA. The as-created CA/PPA-2.0 exhibited enhanced mechanical properties, as evidenced by the fact that its compressive strength rose from 1.3 ± 0.10 to 2.9 ± 0.23 MPa at 90.0% strain compared to that of neat chitosan aerogel. Additionally, compared to CA, the CA/PPA aerogel with 2.0 wt% PPA exhibits significant fire safety performance. For instance, the peak heat release rate, total heat release, maximum average rate of heat emission, and thermal conductivity were reduced by 62.1%, 55.6%, 48.4%, and 12.5%, respectively. In addition, the CA/PPA-2.0 composite aerogel also exhibits a fire-alarm performance under flame attack. This work introduces a feasible strategy to produce high-performance aerogels with promising applications in construction, aerospace, and thermal insulation. Full article

This study investigates a Solar Air Heating Façade (SAHF), architecturally enhanced through the integration of granular translucent Silica-Aerogel into multi-wall polycarbonate (PC) panels and the implementation of coated timber lamellas. The novelty of this work lies in the combined evaluation of thermal resistance and solar transmission properties of façade-integrated components, aiming to improve both energy efficiency and architectural integration. Two experimental campaigns were conducted: (i) thermal transmittance tests to determine the U-value of PC panels with and without Silica-Aerogel infill, and (ii) solar transmission measurements under controlled artificial solar radiation to evaluate the optical performance of various lamella configurations and coatings. Results show that the incorporation of Silica-Aerogel reduced the U-value by 41.8%, achieving a minimum of 1.19 W/m² K with the 20 mm thick PC panel, while decreasing the solar transmission of 43–53% depending on the incidence angle. The integration of reflective aluminum-coated timber lamella demonstrated promising results, enabling effective management of solar radiation. These findings highlight the potential of façade systems that combine high-performance insulation with visually integrated shading elements. Full article

The removal of cationic dyes from industrial wastewater presents a significant environmental challenge. This research examines the effectiveness of functionalized cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. This research provides a systematic comparative study on the effectiveness of four distinct functionalization strategies, carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modification, applied to cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. Cellulose nanocrystals (CNCs) were extracted from sugarcane bagasse waste and subsequently functionalized into carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modified variants. The materials were later integrated into a silica matrix, resulting in the formation of porous aerogel nanocomposites. The materials underwent thorough characterization through FTIR, XRD, SEM, TGA, and BET analyses, validating successful functionalization and the development of mesoporous structures. Batch adsorption tests demonstrated that the CMC-silica aerogel exhibited superior performance, attaining a maximum adsorption capacity of 197 mg/g and complete removal efficiency under ideal circumstances (pH 10, 25 °C, 60 min). The adsorption process is accurately characterized by the Langmuir isotherm and pseudo-second-order kinetic models, signifying monolayer adsorption and chemisorption as the rate-limiting step. The thermodynamic parameters indicate that the adsorption process is exothermic and spontaneous. The CMC-silica aerogel exhibited significant reusability, maintaining over 90% efficiency after six consecutive cycles. The findings illustrate the efficacy of functionalized cellulose–silica aerogels, especially the CMC form, as effective, environmentally sustainable, and reusable adsorbents for the treatment of dye-polluted water. Full article

This study investigates the feasibility of using scrap aerogel (SAG) generated during silica aerogel production as a partial substitute for sand in 3D concrete printing. Through comprehensive experiments and finite element analysis, the printability, thermal insulation properties, and mechanical characteristics (compressive strength and flexural strength) of 3D-printed scrap-aerogel-incorporated concrete (3DP-SAIC) were evaluated at different SAG replacement ratios. The results indicate that the thermal conductivity of the concrete decreases with increasing SAG content. When 30% of the sand is replaced by aerogel, the thermal conductivity perpendicular to the printed layer direction is reduced by 40.90%. The thermal properties of SAIC closely resemble those of aerogel concrete (AIC) while significantly reducing manufacturing costs. Compared to existing 3D-printed aerogel concrete, this study achieves a 73.1% cost reduction. Compared to standard cast specimens (SC-SAIC), 3DP-SAIC exhibits pronounced anisotropic thermal behavior. The study also evaluated the reinforcement effects of four basalt fibers (BF) with different aspect ratios on the mechanical properties of 3DP-SAIC. Although BF provides limited enhancement to compressive strength, it significantly boosts flexural strength. Specifically, BF with a length of 12 mm and a diameter of 17 μm increases flexural strength by 26.97%. These findings highlight the application potential of recycled aerogel in 3D-printed concrete, offering a sustainable thermal insulation solution with suitable mechanical properties for green building technologies. Full article

Recently, the state of the art of aerogels (AGs) has been reviewed, reporting first on their classification, based on the chemical origin of their precursors and the different methods existing to prepare them. Additionally, AGs of inorganic origin (IAGs) were contemplated, deeply discussing the properties, specific synthesis, and possible uses of silica and metal oxide-based AGs, since they are the most experimented and patented AGs already commercialized in several sectors. In this second part review, IAGs are examined again, but chalcogenide and metals AGs (CAGs and MAGs) are debated, since they are still too little studied, patented, and marketed, despite their nonpareil properties and vast range of possible applications. First, to give readers unaware of the previous work on AGs, a background about IAGs, all their main subclasses have been reported and their synthesis, including sol–gel, epoxide addition (EA), and dispersed inorganic (DIS) methods, as well as procedures involving the use of pre-synthesized nanoparticles as building blocks, have been discussed. Morphology and microstructure images of materials prepared by such synthetic method have been supplied. Conversely, the methods needed to prepare CAGs and MAGs, topics of this study, have been debated separately in the related sections, with illustrative SEM images. Their possible uses, properties, and some comparisons of their performance with that of other AGs and not AG materials traditionally tested for the same scopes, have also been disserted, reporting several case studies in reader-friendly tables. Full article

Silica aerogels are highly attractive due to their outstanding properties, including their low density, ultralow thermal conductivity, large porosity, high optical transparency, and strong sorption activity. However, their inherent brittleness has limited widespread applications. Constructing a robust, highly porous three-dimensional network is critical to achieving the desired mechanical properties in aerogels. In this study, we introduce a novel synthesis route for fabricating lightweight and mechanically strong aerogels by incorporating poly(ethylene-co-vinyl alcohol) (EVOH) through thermally induced phase separation (TIPS). EVOH exhibits upper critical solution temperature (UCST) behavior in a mixture of isopropanol (IPA) and water, which can be utilized to reinforce the silica skeletal structure. Robust aerogels were prepared via the sol–gel process and TIPS method, followed by supercritical CO₂ drying, yielding samples with bulk densities ranging from 0.136 to 0.200 g/cm³. N₂ physisorption analysis revealed a mesoporous structure, with the specific surface area decreasing from 874 to 401 m²/g as EVOH content increased from 0 to 80 mg/mL. The introduced EVOH significantly enhanced mechanical performance, raising the flexural strength and compressive strength to 0.545 MPa and 18.37 MPa, respectively—far exceeding those of pure silica aerogel (0.098 MPa and 0.74 MPa). This work demonstrates the effectiveness of the TIPS strategy for developing high-strength, low-density silica aerogels with well-preserved porosity. Full article

Silica aerogel has garnered significant attention in the biomedical field, primarily due to its unique combination of a three-dimensional structure, low density, tunable nanoscale pores, and an extensive surface area. These intrinsic properties render it as an exceptional candidate for advanced drug delivery systems (DDSs). In the realm of medical applications, silica aerogels have demonstrated remarkable potential, especially in nanoscale DDSs. Traditional drug delivery methods, such as capsules and tablets, are often plagued by several drawbacks, including poor bioavailability, lack of target specificity, and multidrug resistance. These limitations necessitate the development of more efficient and targeted drug delivery systems. Recent advancements in the synthesis and modification of silica aerogels have significantly enhanced their biocompatibility and functionalization capabilities. These improvements have further bolstered their potential for controlled release and targeted delivery of therapeutic agents. This study is based on silica aerogel-based nanocarrier systems, providing an in-depth exploration of its fundamental principles, preparation processes, and recent advancements. Based on this, we summarize the drug delivery methods, drug release characteristics, and diverse medical applications of silica aerogels. Additionally, we discuss the challenges and future prospects of applying silica aerogels in drug delivery systems, aiming to provide a comprehensive overview of this field. Full article

This review establishes a comprehensive technical framework for aerogel-based fire-resistant coatings, from fundamental mechanisms to industrial applications. It analyses the multi-mode flame-retardant and thermal insulation mechanisms achieved through aerogels’ synergistic suppression of heat conduction, convection, and radiation, establishing their theoretical basis. The work compares the intrinsic characteristics of silica-based, carbon-based, and bio-based aerogels, providing rational selection criteria for fire protection systems. The study examines key integration challenges: balancing nanopore preservation with interfacial compatibility, inherent mechanical weaknesses, conflicts between high filler loading and workability, and scalability issues. It evaluates targeted strategies including interface engineering, mechanical reinforcement, workability optimization, and low-cost production routes. Application prospects in construction, tunneling, and cable protection are outlined. This review provides a coherent progression from mechanisms and material properties to challenges and solutions, offering theoretical guidance and a technical roadmap for developing next-generation high-performance fire-resistant coatings. Full article

The insistent presence of detrimental chemical dyes, such as methylene blue (MB), in aquatic ecosystems creates a significant environmental fear that requires the development of innovative and effective remediation methods. This study examines the production and application of a novel carboxylate cellulose nanocrystal-silica-titanium dioxide (CCNC-silica-TiO₂) hybrid composite aerogel designed to enhance the photocatalytic degradation of methylene blue (MB). Carboxylic groups were incorporated into cellulose nanocrystals (CNCs) derived from sugarcane bagasse (SCB) waste to improve their dye adsorption capacity. The CCNCs were later incorporated into a silica aerogel matrix using a sol–gel method, followed by the introduction of TiO₂ nanoparticles. Characterization techniques, including FTIR and XRD, confirmed the successful chemical functionalization and composite synthesis. SEM analysis revealed a highly porous three-dimensional architecture, whilst BET surface area assessment showed that the CCNC-SiO₂-TiO₂ aerogel possessed a significant specific surface area of 448.69 m²/g. Under ultraviolet light, the hybrid aerogel demonstrated remarkable photocatalytic performance, achieving a 93% degradation rate of methylene blue, far above the 22% recorded in a CCNC-silica control. The degradation kinetics followed a pseudo-first-order model. The composite demonstrated significant reusability, maintaining over 70% efficiency after five consecutive cycles. The findings indicate that the adsorptive capacity of carboxylate CNCs, together with the photocatalytic efficiency of TiO₂, improves the efficacy, stability, and longevity of the CCNC-SiO₂-TiO₂ aerogel in wastewater treatment. Full article