Preparation Of Aerogels Research Articles

Synthesis of zirconium-based metal-organic framework/gelatin aerogel for removing phosphate and fluoride from aqueous solutions.

This study describes the preparation of novel hybrid aerogels derived from gelatin (Gel), incorporating Br-functionalized zirconium-based metal-organic framework (UiO-66-Br; MOF) as modifying agent to effectively eliminate phosphate and fluoride ions from aqueous environments. The adsorption performance of MOF decorated Gel (Gel-xMOF) hybrid aerogels was investigated under different conditions, including agitation time, adsorbent dosage, solution pH, initial phosphate and fluoride concentrations, coexisting ions, and temperature. The functional groups of the gelatin network, coupled with UiO-66-Br, enhanced the adsorption performance of phosphate and fluoride ions from aqueous solutions. The structural features and physicochemical parameters were evaluated using several characterization tools. The mesoporous Gel-1.5MOF aerogels exhibited Langmuir adsorption capacities of 20.81 and 7.42 mg/g for phosphate and fluoride, respectively. Reusability and coexisting experiment results suggest that the as-prepared Gel-1.5MOF aerogels have the potential for practical applications. Electrostatic attraction and ligand exchange primarily govern the adsorption mechanism of both ions, followed by hydrogen bonding and pore-filling mechanisms. This investigation offers new insights into the successful elimination of phosphate and fluoride ions across a broad pH range.

One-step preparation of waste epoxy resin-derived nanosized carbon aerogel and its high supercapacitor performance

Energy storage devices serve critical roles in both harvesting energy from new energy sources and supplying energy to consumers, and the performance of supercapacitors is heavily reliant on the performance of activated material, which is determined by the qualities achieved during the specified preparation process. Herein, due to the merit of isotropy of 0D carbon nanoparticles in structure and current transfer, spherical carbon aerogels (CA) with the size of ϕ ~ 100 nm are carbonized within 3 min in air in an open tube furnace, in which those waste epoxy resin blocks are chosen and reused as the carbon source. After the activation, the surface of activated CA (ACA) becomes rough, and its specific surface area reaches 1222.40 m2·g−1. The above ACA owns high electrochemical supercapacitor performance: Referring to the ACA-based electrode, a specific capacitance of 298.8 F·g−1 at 1 A·g−1 (vs. 2.0 F·g−1 for CA) and 92.81 % retention after 20,000 cycles of repeated charge/discharge. As for its symmetric supercapacitor (SSC), it has good CV behavior even at 1000 mV·s−1, accompanied by an energy density of 20.92 W h·kg−1 at the power density of 300 W·kg−1, and 12.34 W h·kg−1 even at 12000 W·kg−1.

Preparation of polymer-coated SiO2 aerogel for weakening wellbore instability caused by heat transfer between the drilling fluid and well wall

Preparation of polymer-coated SiO2 aerogel for weakening wellbore instability caused by heat transfer between the drilling fluid and well wall

Biomimetic biomass-based composite carbon aerogels with excellent mechanical performance for energy storage and pressure sensing in extreme environments.

The poor mechanical properties of biomass-based carbon aerogels after carbonization severely limit their application in pressure sensing and energy storage for wearable devices and electronic skin. In this work, a supramolecular assembly structure was designed inspired by the unique microstructure of natural wood for the preparation of biomass-based carbon aerogels with supercompressibility, elasticity, stable strain electrical signal response, and wide sensitive detection. Bacterial cellulose and lignin were selected as the main components of the biomass-based composite aerogel 'cell wall'. The graphene oxide with an aromatic structure was introduced to induce the assembly of firmly attached lignin and bacterial cellulose. The prepared biomass-based carbon aerogels exhibit supercompressibility (at least 100 cycles at 90% strain), high elasticity (88.88% height retention after 1000 cycles at a strain of 50%), surprising temperature-constant superelasticity and fatigue resistance (shape retention rate greater than 85%) at -196 ℃. In particular, it exhibits temperature-invariant high linear sensitivity over an extremely wide operating pressure range (0-43kPa), allowing accurate detection of human signals. In addition, the prepared carbon aerogels exhibit excellent performance in supercapacitors. It has a specific capacitance of 158F/g at a current density of 1 A/g and an energy density of 18.75 Wh/kg at a high power density of 2500W/g. This strategy also demonstrates its promise as a wearable device in hostile environments.

Preparation of PET-based aerogels from post-consumer packaging waste

Preparation of PET-based aerogels from post-consumer packaging waste

Black Aerogel Based on Short‐Time High‐Flux He Ion Implantation

AbstractOwing to ultra‐lightweight and integrable functionality, black aerogels are applied as light‐shielding units in complex optical systems. However, the preparation of most black aerogels involves complex and time‐consuming carbonization processes to induce carbon particles. Inspired by the barb structure of the black feathers, a simple and short‐time approach by using helium (He) ion implantation to obtain black silica aerogel, which possesses microscale, biomimetic cone arrays with several microcavities, is introduced. Benefiting from this multilevel structure, only a thin surface of ≈47 µm is required to realize evident light shielding with ≈3% transmittance and ≈2% reflectivity in the visible region. This film also possessed considerable photothermal conversion, which increased to more than 65 °C from room temperature under 1 sun energy density. Meanwhile, the realization of this black surface inherits the excellent properties of the aerogel, such as porosity, high specific surface area, and low density. This work presents a simple and effective technique for preparing black surfaces based on aerogel monoliths, holding potential for use in photocatalysis, photothermal therapy, and light stealth.

A Facile Strategy for In Situ Fabrication of Covalent Triazine Framework Aerogel with Thermal Insulation Property.

Covalent triazine frameworks (CTFs) have attracted tremendous attention with respect to their rich nitrogen content, functional triazine units, and high porosity. However, efficient and simple preparation of CTF monoliths is still a challenge. Here, we propose a novel and facile approach for the in situ preparation of CTF aerogels. Trifluoromethanesulfonic acid was used as the solvent and catalyst, which could not only promote the polymerization reaction to form a gel but also protonate the CTFs. By virtue of the simplicity and efficiency of the strategy, a series of macroscopic CTF aerogels with tunable density were obtained by adjusting the monomer concentration. Due to the porous and partially crystalline structure, the as-produced macroscopic CTF aerogels behaved with good mechanical and thermal insulation performances. This finding thus offers an effective and easily scalable approach toward fabricating macroscopic CTF aerogels and broadens the applications of CTFs in a variety of domains.

Preparation of lamellar-structured carboxymethyl cellulose aerogels for efficient sound absorption

Preparation of lamellar-structured carboxymethyl cellulose aerogels for efficient sound absorption

Novel ultralight carbon foam reinforced carbon aerogel composites with low volume shrinkage and excellent thermal insulation performance

Lightweight carbon aerogels are attractive for thermal insulation due to their low thermal conductivity and excellent high-temperature resistance under extreme environments. However, the preparation of monolithic carbon aerogels from phenolic resin precursor always faces the problem of large volumetric shrinkage during the drying and carbonization processes, thus resulting in the increasing density and thermal conductivity of aerogels. Here, to solve such issues, ultralight and rigid carbon foam was designed and synthesized as the reinforcement to fabricate carbon aerogel composites (CACs), which could significantly enhance the shrinkage resistance of monolithic carbon aerogels. The high rigidity of the carbon foam reinforcements (CFRs) was achieved through a pre-carbonization process, which also endowed the CFRs with a matched shrinkage with the monolithic carbon aerogels. As a result, the obtained CACs reinforced by the rigid CFRs showed not only crack-free structures, but also quite low shrinkage, which was about 5.9 % after carbonization. The low shrinkage of CACs then endowed them with quite low density (21.5 mg cm−3) and excellent thermal insulation performance (25.9 mW m−1 K−1). Furthermore, due to a highly rough nanostructure, the CACs also possessed outstanding hydrophobicity. These merits make the CACs a promising thermal insulation material even in humid environments.

Preparation and adsorption properties of polyetherimide graft-reinforced cellulose aerogels

Preparation and adsorption properties of polyetherimide graft-reinforced cellulose aerogels

A Versatile Method for Preparation of BrCOFs Aerogels and Efficient Functionalization via Suzuki-Miyaura Reaction.

Covalent organic frameworks (COFs) aerogels solve the restrictions on processability and application caused by the insolubility and non-fusibility of powders while avoiding the inaccessibility of pore structures by dense stacking. At the current start-up stage where COFs aerogels are scarce and difficult to synthesize, design of generalized synthetic methods play an indispensable role in guiding and developing COFs aerogels. Moreover, evolving the functionality of COF aerogels is equal vital, which achieves higher performance and broader practical applications. In this work, for the first time, processable BrCOFs aerogels have been synthesized without vacuum by seven kind polar solvents, which realizes general preparation of BrCOFs aerogels. It is extremely friendly to the inapplicability for some scenarios. Furthermore, by Suzuki-Miyaura cross-coupling reaction, BrCOFs aerogels are endows with cyano groups (-CN), trifluoromethyl (-CF3) and methyl sulfonyl (-SO2-CH3) efficiently. As a proof-of-concept, BrCOFs-SO2-CH3 aerogels served as a quasi-solid electrolyte for lithium-metal batteries (LMBs), which effectively enhance the performance of batteries.

A novel bio-aerogel based on agroforestry waste chestnut shell for enhanced oil-water separation performance

Bio-based aerogels have attracted much attention due to their biodegradability and excellent oil-water separation properties. However, the preparation of inexpensive green aerogels with high separation efficiency is still a great challenge. In this paper, low-density, high-adsorption capacity and superhydrophobic chestnut shell-based bio-aerogels were prepared by chemical cross-linking and chemical vapor deposition using agricultural and forestry waste chestnut shells as the precursor of aerogels to achieve high efficiency of oil-water separation and to achieve the goal of “treating waste with waste”. The covalent cross-linking of chestnut shell cellulose and cross-linking agent to form silicone-containing functional groups improved the pore structure, hydrophobicity and mechanical properties of chestnut shell cellulose, and under the action of capillary force, the oil was retained in the pores of the bio-aerogels, which achieved the selective adsorption of oil and organic solvents in the oil-water mixture, with a separation efficiency of more than 98 %. After 10 cycles, the bio-aerogel still has good reusability. This eco-friendly and low-cost aerogel provides a practical method for resource conversion and recycling, as well as a green and innovative way for the treatment of oily wastewater.

Preparation of SiO2 aerogel by water glass: effect of different sodium removal methods on aerogel properties

Preparation of SiO2 aerogel by water glass: effect of different sodium removal methods on aerogel properties

Preparation and physical properties of basalt fiber-reinforced silica aerogels

Preparation and physical properties of basalt fiber-reinforced silica aerogels

A Facile Strategy for Freeze-Drying Preparation of Silica Aerogel from Sodium Silicate

Silica aerogels have attracted widespread attention for their distinct nanoporous networks, composed of interconnected silica nanoparticles and high-volume nanosized pores. Nonetheless, producing silica aerogels with low costs and simple processes still remains a considerable challenge. Herein, the mesoporous silica aerogels were prepared from inorganic silicon source through the freeze-drying. Using sodium silicate as the silica precursor, the gel was formed by the ion exchange and sol-gel in sequence. The regeneration of the weak acidic ion exchange resin produced the sodium acetate solution, which can be potentially used as carbon source for sewage treatment. To eliminate the collapse of microstructure of the silica hydrogel during freeze-drying, the tert-butanol aqueous solution was used as the freeze-drying medium. Particularly, the direct mixing of tert-butanol and silica sol to generate wet gel avoids prolonged and material-consuming solvent replacement. The pore structure of mesoporous silica aerogel can be adjusted by changing the concentration of tert-butanol solution. The 18 wt% tert-butanol solution results in the most favorable mesoporous structure of silica aerogel, owing to the eutectic behavior within the gel, which was verified by differential scanning calorimetry (DSC) analysis, and also due to the superior and uniform mesoporous structure of wet gel, which was validated by the cryogenic scanning electron microscopy (cryo-SEM) observation. Under optimal process conditions, the obtained silica aerogel exhibited a high porosity (97.74%) and typical mesoporous structure with the large pore volume (4.84 cm3·g-1) and an average pore diameter of 24.40 nm. The proposed cost-effective preparation strategy could elevate the potentials for large scale applications of silica aerogels in the fields of thermal insulation for building, industrial catalysis and adsorption, etc.

Biomimetic Ambient‐Pressure‐Dried Aerogels with Oriented Microstructures for Enhanced Electromagnetic Shielding

AbstractOriented aerogels, emerging as a new generation of lightweight electromagnetic interference (EMI) materials, often face complex synthesis processes. While creating an orderly oriented microstructure for EMI aerogels through ambient pressure drying (APD) shows promise, it remains a significant challenge. Here, inspired by the directional grown structure of the plant, a new strategy that employs rapid precursor orientation followed by slow cross‐linking to achieve the APD of directional EMI aerogels is proposed. This approach demonstrates that low‐temperature oriented polymerization of polyaniline enables strong cross‐linking with poly(3,4‐ethylenedioxythiophene) and alginate, forming a robust conductive directional skeleton and mitigating surface tension issues during mild drying. The resulting aerogel features high conductivity (48.84 S m−1), excellent flame retardancy, and impressive compressive strength. Notably, its sturdy frame allows for further enhancement with other functional materials, such as Mxene, through re‐processing and re‐drying. The tree‐branch‐like aerogel achieves a significantly improved EMI shielding effectiveness of 50.3 dB across an ultrawideband range of 8.2–40 GHz. This strategy offers a new idea for the straightforward preparation of functional aerogels with programmability and oriented microstructures using ambient drying.

Ceramic Microsphere Aerogels by Curled Precursor Molecular Chain: Antishrinkage, Thermal Insulation and Multiscale Simulations.

Ceramic aerogels prepared by the route of polymer-derived ceramics (PDCs) have been of significant attention in high-temperature insulation. However, the application of ceramic aerogels was seriously confined due to the structural damage and shrinkage cracking of ceramic precursors during pyrolysis. In this investigation, precursor ceramic microsphere aerogels with outstanding antishrinkage properties were prepared by storing strain in curled molecular chains and using polysilazane (PSZ) as the precursor. Meanwhile, precursor ceramic microsphere aerogels with different curled molecular chain structures were prepared by modulating solvent interactions and cross-linked structures. Different curled molecular chain structures were formed, and the impact on the antishrinkage properties of precursor aerogels was analyzed. The shrinkage resistance, thermal insulation, and mechanical properties of the prepared aerogels were tested and compared. Furthermore, the mechanism of the impact of different curled molecular chain structures on thermal insulation and mechanical properties was investigated through multiscale simulations combined with fractal theory. The thermal and stress transfer at the interfaces of different microsphere skeleton structures and the mechanisms were investigated. An idea for solving the problem of pyrolytic shrinkage in the preparation of ceramic aerogels was provided in this investigation. In addition, insights into the influence of the microsphere skeleton structure on the thermal and mechanical properties of ceramic aerogels were provided.

Graphene aerogel with double pore structure for marine oil spill emergency response

Due to its high porosity, large specific surface area, and strong photothermal conversion performance, graphene aerogel has unique advantages in the field of pollution treatment, especially in the field of recovering highly viscous oils. However, for the treatment of highly viscous oils, the high adsorption capacity and high adsorption rate of graphene aerogel often cannot be combined, which is one of the important reasons limiting its development in this field. A double-step templating strategy for graphene aerogels preparation was used in this work, i.e., Pickering emulsion soft templating and unidirectional freeze casting. Specifically, the dense Pickering emulsion droplets can be stabilized in a short period of time, so that they can be cured quickly. After that, graphene aerogels (DGA-0.8-25) with dual pore structure were prepared by unidirectional freeze casting technology to further form aligned pores based on the pores formed by the Pickering emulsion droplet soft template. The dense presence of Pickering emulsion droplets gives DGA-0.8-25 an ultra-high porosity (96.8 %), which can adsorb 184.53 times its own mass of crude oil. Due to the unidirectional pore structure, the adsorption rate of DGA-0.8-25 on crude oil is as high as 8.39 g·g−1·min−1, which realizes dual improvement of the adsorption capacity and rate of graphene aerogel on crude oil and shows a good application prospect in the treatment of high viscosity crude oil. In addition, DGA-0.8-25 has unique advantages in the field of oil–water separation, with a separation efficiency of 99.04 % for water-in-oil emulsions and 97.63 % for oil-in-water emulsions. When repeated used in photothermal adsorption of highly viscous oil, DGA-0.8-25 can still maintain more than 90.61 % of its initial adsorption capacity after ten cycles of use-regeneration. Because of its unique advantages such as high efficiency and low cost, DGA shows promising in its future large-scale use.

Low cost Non freeze-drying construction strategy of cellulose aerogels for efficient solar desalination

Aerogel-like materials with three-dimensional pore structures show great potential in the field of efficient solar-driven interfacial evaporation by virtue of their fast water transport as well as efficient energy confinement properties. However, the preparation of aerogels is currently limited by high-cost strategies such as freeze drying or supercritical drying. Here, we present a foam template-assisted (FTA) strategy for atmospheric pressure drying of cellulose nanofiber (CNF) aerogels. Building a robust CNF network is the key to resisting surface tension during water evaporation and achieving drying in ambient environments, which is achieved through cleverly designed ionic cross-linking with the help of FTA. Cellulose aerogel (CA) constructed using the FTA strategy exhibit lightweight (9 mg cm−3) and porous properties (porosity: > 99 %). The tannic-coated CA (TCA) was achieved by further polymerizing tannic acid on the CA surface, which has excellent photothermal conversion capability. Meanwhile, TCA achieved an impressive evaporation rate of 3.58 kg m-2h−1 and an energy efficiency of 97.2 % at 1sun radiation by virtue of its excellent energy confinement and water management capabilities. This strategy provides a promising solution for the low-cost construction of aerogels as well as for the realization of efficient solar-driven interfacial evaporators.

Preparation and Properties of Flexible Phenolic Silicone Hybrid Aerogels for Thermal Insulation

In order to prepare flexible thermal protection aerogel materials, using dimethyldimethoxysilane (DMDMS) and methyltrimethoxysilane (MTMS) as co-precursors, isocyanate-propyltrimethoxysilane (CFS-006) was added to the co-precursor as a coupling agent, and resorcinol and formaldehyde were added to the sol solution to prepare a phenolic silicone hybrid aerogel (FAS) by the sol–gel method. The prepared FAS aerogel had no phase separation problem, the density was only 0.118 g/cm3, the hydrophobic angle reached 155.3°, and it had certain flexibility. It could be compressed to 70% and still be restored to its original state. The FAS aerogel also had a low thermal conductivity of 0.0318 W/(m·K) and good high temperature insulation. The introduction of phenolic groups improved thermal stability; Tmax increased to 643.7 °C, and the residual carbon rate was 24.5%. This work has positive significance for the future combination of aerogels and textiles in the preparation of firefighting protective clothing.