Biomass-based Aerogels Research Articles

Ti3C2TX MXene/loofah-derived carbon aerogel for high-efficiency adsorption of organic pollutants in wastewater

The contamination of wastewater by organic pollutants significantly impacts human health and the environment due to their carcinogenic nature and various adverse effects. To address this issue, this study offers a high-efficiency and low-cost biomass-based carbon aerogel adsorbent, which was prepared through the hydrothermal carbonization of loofah, followed by Ti3C2TX MXene impregnation. The aerogel features a porous three-dimensional network structure and a substantial specific surface area, facilitating broad-spectrum adsorption capabilities for various dyes and drugs. The aerogel achieved impressive adsorption capacities of 175.29 and 75.73 mg/g for cationic methylene blue and Rhodamine B dyes, and 106.33 and 93.29 mg/g for anionic methyl orange and Congo red dyes, as well as 86.25 mg/g for tetracycline hydrochloride, surpassing other reported biomass-based aerogels. Furthermore, it demonstrated effective decolorization ability for wastewater containing mixed dyes. Notably, it exhibited excellent recycling and regeneration properties, maintaining a high removal rate after multiple cycles of adsorption–desorption. The adsorption process of dye/drug by the aerogel followed Langmuir’s monomolecular layer adsorption model, exhibiting spontaneous, endothermic, and disorder-increasing behavior in alignment with the pseudo-second-order kinetic model. This study presents an efficient biomass-based aerogel for the removal of organic pollutants from wastewater.

Fully biobased thermal insulating aerogels with superior fire-retardant and mechanical properties

Biomass-based aerogels offer a promising potential as alternatives to plastic-based foams for thermal insulation applications. However, their inherent flammability has hindered their practical usage. In this work, we addressed this issue by employing a layer-by-layer assembly technique to deposit two oppositely charged biobased materials, namely phytic acid and chitosan, onto a fully biobased aerogel system. These aerogels were fabricated using cellulose filaments and chitosan and cross-linked with citric acid, resulting in a mechanically robust 3D structure. The synergistic effects of phytic acid and chitosan in the layer-by-layer deposited aerogels significantly enhanced their fire resistance and mechanical strength. The developed aerogel with six bilayer depositions (LBL6), showed an outstanding peak heat release rate (pHRR) of 6.0 kW.m−2, and total heat release (THR) of 0.4 MJ.m−2, substantially lower than the previously developed cellulose-based aerogels and foams. LBL6 also demonstrated immediate self-extinguishing behaviour, boasting an impressive limiting oxygen index (LOI) value of 63 %, which is the highest reported for a biobased aerogel. Furthermore, the developed aerogels exhibited a superior Young’s modulus of up to 4.5 MPa, surpassing previously developed flame-retardant aerogels. Additionally, they excelled in thermal insulation properties, with a thermal conductivity of less than 38.2 mW·m−1·K−1, placing them in the same range as, or even lower than, commercially available thermal insulators. Given the simplicity of the aerogel development process and the well-known advantages of a completely biobased system, our developed aerogels present a sustainable and environmentally friendly alternative to current commercial thermal insulators that are derived from petroleum-based materials.

Fabrication of superhydrophobic all-biomass aerogels with ultralight, elasticity and degradability for efficient oily wastewater treatment

Oily wastewater has seriously threatened the water ecology and human health. Superhydrophobic biomass-based aerogels are ideal candidates to remedy the oily wastewater, but facing challenges for the usage of toxic small molecules crosslinker and the rational construction of elasticity. Herein, we employed the natural non-toxic citral as crosslinker, and then constructed a superhydrophobic chitosan/bamboo cellular fibers aerogel (S-CS/BCF-A) with ultra-light, high elasticity and degradation performances. Wherein the hydrolysis of methyltrichlorosilane produced silicon hydride and hydrogen chloride, enhanced the hydrophobicity of the aerogel surface and partially reduced rigidity of the pore walls, respectively. The S-CS/BCF-A displayed outstanding fatigue durability, which benefited for its lamellar-fiber interweaved structure. In addition, this aerogel could undergo tape-peeling, UV radiation, and organic solvents immersion without superhydrophobic variation, even in seriously abrasing that the surface still maintained high hydrophobicity. The as-made aerogel possessed high oil adsorption capacity (17.95–44.57 g/g), combined with pump-supported device for effectively recovering large-area oil spills (66,348 L·m−2·h−1). Furthermore, the resultant aerogel could efficiently separate the immiscible oil-water mixture and emulsifying wastewater (types of Oil-in-Water and Water-in-Oil emulsions). This work provides a rational design method for constructing the elastic, durable and biodegradable aerogels, used for speedy and economical separation of oil-water mixtures.

Eco-friendly biomass aerogels from moxibustion waste for sustainable remediation of organic contaminants

Powder adsorbents present limited recyclability when used for wastewater treatment. Bulk materials prepared via eco-friendly approaches typically exhibit excellent reproducibility over powders in terms of removing pollutants from aquatic environments. Here, biomass-based aerogels were synthesized via ball milling a mixture of modified moxa ash (a type of moxibustion waste), carbon nanotubes and ammonia, combined with agarose as biomolecule. The obtained aerogels display low density, high porosity, remarkable mechanical properties, and exceptional repeatability and stability for removing organic pollutants. By employing a two-dimensional (2D) aerogel membrane, pollutants such as 10 mg/L mitoxantrone (MTX), 5 mg/L methylene blue, 5 mg/L malachite green, or 5 mg/L rhodamine B could be dynamically adsorbed and swiftly filtered out, achieving nearly 100 % of the removal rate. For three-dimensional (3D) aerogels, efficient removals of MTX (98.4 % at 135 min) and cationic dyes under various conditions were observed, in which the adsorption capacity reached 28.23 mg/g for low concentration of MTX at 120 min. After four cycles, the aerogel still retained 93 % of its original capacity and the removal rate was still 92.4 %. The adsorption process obeys second-order kinetics and adheres to the Freundlich and Temkin isotherm models. Furthermore, the primary mechanism by which the aerogels adsorb MTX includes pore filling, electrostatic interactions, π-π conjugation and hydrogen bonding. The adsorption mechanism was better explained by the results of density functional theory. Biomass-based 2D/3D aerogels are promising, low-cost, eco-friendly and highly efficient absorbents for mitigating wastewater contamination.

Hierarchical aerogels based on cellulose nanofibers and long-chain polymers for enhancing oil–water separation efficiency

The hydrophobic chain length of biomass-based aerogels used for oil–water separation was evaluated as a major parameter influencing the aerogels’ hydrophobicity. The properties of the porous structure were enhanced by the hierarchical assembly of the aerogels with biopolymeric structural units and polymer mineralization. The cellulose network was strengthened through silanization, and the nanocellulose network was further enhanced through coating with mineralizers containing long-chain hydrophobic molecules. Interfacial engineering was employed to establish multiscale interactions through the freeze-drying-induced modification of cellulose nanofibers and mineralized coatings of long-chain alkyl polymers. The resulting hierarchically structured aerogel exhibits low density (11.4 kg/m3), excellent mechanical compression properties across a wide temperature range (capable of enduring 100 cycles of compression), high porosity (99.2%), superhydrophobicity (152°), and recyclability. It maintains a 57.9% adsorption rate even after 40 adsorption–desorption tests, while also preserving its shape integrity. Moreover, it can be recycled and reused. At a temperature of 700 °C, the mass loss was only 44.47%, with excellent thermal stability. The aerogel can reduce oil pollutants in the ocean by adsorption, recover oil resources, and protect the natural environment. The assembly and optimization of nanofibrous matrix interfaces through the mineralization of long-chain polymers enhanced the performance of functionalized cellulose-based aerogels.

Renewable biomass-based aerogels: from structural design to functional regulation.

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Efficient thermal insulation through all-biomass silk fibroin composite aerogel 3D-reinforced by natural down-fiber

Biomass-based aerogels offer numerous individual benefits in thermal insulation applications. However, their generally weak mechanical properties impair the further development of aerogels. Herein, natural down-fiber (DF) reinforced silk fibroin (SF) all-biomass aerogel was rationally designed. The developed 3D-reinforcement structure, in which DF was physically interspersed in SF in multiple directions and hydrogen bonds formed between DF and SF, resulted in significantly enhanced compression stress of 146.3 kPa (3.44 times greater than that of SF aerogel, which attained 42.57 kPa) and impressive compression resilience. Meanwhile, the DF@SF aerogel displayed a hierarchical porous structure (97.64 % porosity) with micron-sized holes and nano-sized pores, as well as low thermal conductivity of 0.034 W m−1 K−1, which would effectively inhibit air circulation and limit heat transfer for improved thermal insulation. Moreover, the addition of DF reduced the average hole diameter, which further prevented heat convection and minimized heat radiation inside the aerogel. As a result, the DF@SF aerogel demonstrated excellent thermal insulation performance with a wide range of working temperatures from −40 to 160 °C and stability for recyclable usage. Therefore, this all-biomass DF@SF aerogel could offer an alternative form of high-performance thermal insulation. This strategy will also inspire more research into the construction of 3D-reinforced functional aerogels and their applications in thermal insulation, sound insulation, biomedicine, and other related areas.

Amino-functionalized biomass-based aerogel derived from waste reed converted into an efficient photocatalyst after adsorption of Cu2+

Amino-functionalized biomass-based aerogel derived from waste reed converted into an efficient photocatalyst after adsorption of Cu2+

Compressible polydopamine modified pomelo peel powder/poly(ethyleneimine)/κ-carrageenan aerogel with pH-tunable charge for selective removal of anionic and cationic dyes

In this work, a novel biomass-based aerogel, polydopamine decorated pomelo peel powder/polyethyleneimine/κ-carrageenan (PPEKC) aerogel, was developed for dye wastewater treatment. The as-prepared PPEKC aerogel possessed a robust structure and good compressible resilience. As expected, this aerogel presented remarkable efficacy in eliminating both anionic and cationic dyes. The experimental maximum adsorption capacities were 2016.7 mg g−1 for congo red (CR) at pH = 5 and 1176.6 mg g−1 for methylene blue (MEB) at pH = 11, following with ultra-fast adsorption rates. The adsorption kinetics followed the pseudo-second-order model. The adsorption isotherms exhibited a stronger alignment with the Langmuir isotherm model for CR at 308 K and MEB at 288, 298, 308 K. The Freundlich isotherm model yielded a suitable fit for the adsorption of CR at 288 and 298 K. Thermodynamic analyses indicated that the removal of CR and MEB was spontaneous and endothermic. The adsorption mechanisms involved electrostatic interactions, π-π interactions, and hydrogen bonds. Intriguingly, it could achieve bidirectional selective adsorption of anionic and cationic dyes in the designed pH values, due to pH-tunable surface charge. Additionally, it also exhibited favorable reusability and antibacterial activity. Therefore, the as-prepared PPEKC aerogel could be a promising biosorbent for dye wastewater treatment.

"Rigid-Flexible" Anisotropic Biomass-Derived Aerogels with Superior Mechanical Properties for Oil Recovery and Thermal Insulation.

Aerogels with low density, high mechanical strength, and excellent elasticity have a wide potential for applications in wastewater treatment, thermal management, and sensors. However, the fabrication of such aerogels from biomass materials required complex preparation processes. Herein, a sustainable and facile strategy was reported to construct lignin/cellulose aerogels (LCMA) with three-dimensional interconnected structures by introducing homologous lignin with a polyphenyl propane structure as a structural enhancer through a top-down directional freezing approach, prompting a 2036% enhancement in compressive modulus and an 8-12-fold increase in oil absorption capacity. In addition, the hydrophobic aerogels with superelasticity were achieved by combining the aligned polygon-like structure and flexible silane chains, which exhibited remarkable compressional fatigue resistance and superhydrophobicity (WCA = 168°). Attributed to its unique pore design and surface morphology control, the prepared aerogel exhibited excellent performance in immiscible oil-water separation and water-in-oil emulsion separation. Due to the ultra-low density (8.3 mg·cm-3) as well as high porosity (98.87%), the obtained aerogel showed a low thermal conductivity (0.02565 ± 0.0024 W·m-1·K-1), demonstrating a potential in insulation applications. The synthetic strategy and sustainability concept presented in this work could provide guidance for the preparation of advanced biomass-based aerogels with unique properties for a wide range of applications.

Facile and efficient chitosan-based hygroscopic aerogel for air dehumidification

Sorption dehumidification, as an energy-saving and eco-friendly approach, has been emerging in application for air dehumidification. Here, a prospective method is proposed to prepare biomass-based hygroscopic aerogels that are easily applicable, sustainable, high-efficient, and recyclable. The chitosan-based aerogel with a porous and hydrophilic network acts as the carrier and water reservoir for the uniformly distributed lithium chloride hygroscopic salt, and provides the hygroscopic salt with more liberal water channels to facilitate moisture capture and transfer. As a consequence, the prepared chitosan/polyvinyl alcohol@lithium chloride (chitosan/PVA@LiCl) hygroscopic aerogel exhibits an excellent moisture absorption capacity of up to 2.77 g g−1 at a relative humidity of 90 %. Meanwhile, as the chitosan/PVA@LiCl aerogel is set in a closed space about 2200 times larger than its own volume, the relative humidity can be reduced from 90 % to 32 % within 2 h, and further lower to 25 % after 4 h. Furthermore, combined with multi-walled carbon nanotubes, the photothermal hygroscopic aerogel is obtained that can rapidly desorb water under sunlight, thus to realize energy-free cycle. Overall, the renewable biomass-based aerogel materials with the advantages of simple preparation and excellent hygroscopic performance provides a new path for the development of sorption dehumidification technology.

Ultralight and highly efficient oil-water selective aerogel from carboxymethyl chitosan and oxidized β-cyclodextrin for marine oil spill cleanup

Biomass-based aerogels for oil spill cleanup have attracted tremendous research interests due to their feasibility in oil-water separation. However, the cumbersome preparation process and toxic cross-linking agents hinder their application. In this work, a facile and novel method to prepare hydrophobic aerogels is reported for the first time. Da-β-CD/CMCS aerogel (DCA), Da-β-CD/CMCS/PVA aerogel (DCPA), and hydrophobic Da-β-CD/CMCS/PVA aerogel (HDCPA) were successfully synthesized via the Schiff base reaction between carboxymethyl chitosan (CMCS) and dialdehyde β-cyclodextrin (Da-β-CD). Meanwhile, polyvinyl alcohol (PVA) acted as reinforcement and hydrophobic modification was conducted via chemical vapor deposition (CVD). The structure, mechanical properties, hydrophobic behaviors and absorption performance of aerogels were comprehensively characterized. The results indicated that the DCPA containing 7 % PVA exhibited excellent compressibility and elasticity even at a compressive strain of ε = 60 %, however, the DCA without PVA showed incompressibility, suggesting that the important role played by PVA in improving compressibility. Moreover, HDCPA possessed excellent hydrophobicity (water contact angle up to 148.4°), which could be well maintained after experiencing wear and corrosion in harsh environments. HDCPA also possesses high absorption capacities (24.4–56.5 g/g) towards different oils with satisfied recyclability. These advantages endow HDCPA with great potential and application prospects in offshore oil spill cleanup.

Multifunctional cellulose-based aerogel for intelligent fire fighting

Multifunctional biomass-based aerogels with mechanically robust and high fire safety are urgently needed for the development of environmentally-friendly intelligent fire fighting but challenging. Herein, a novel polymethylsilsesquioxane (PMSQ)/cellulose/MXene composite aerogel (PCM) with superior comprehensive performance was fabricated by ice-induced assembly and in-situ mineralization. It exhibited light weight (16.2 mg·cm−3), excellent mechanical resilience, and rapidly recovered after being subjected to the pressure of 9000 times of its own weight. Moreover, PCM demonstrated outstanding thermal insulation, hydrophobicity and sensitive piezoresistive sensing. In addition, benefiting from the synergism of PMSQ and MXene, PCM displayed good flame retardancy and improved thermostability. The limiting oxygen index of PCM was higher than 45.0 %, and it quickly self-extinguished after being removed away from fire. More importantly, the rapid electrical resistance reduction of MXene at high temperature endowed PCM with sensitive fire-warning capability (trigger time was less than 1.8 s), which provided valuable time for people to evacuate and relief. This work provides new insights for the preparation and application of the next-generation high performance biomass-based aerogels.

Efficient recovery of highly viscous crude oil spill by superhydrophobic ocean biomass-based aerogel assisted with solar energy

The crude oil spills is one of the crucial ocean environmental disaster. The low fluidity of high-viscosity crude oil poses significant challenges for its penetration into conventional porous adsorption materials. Fortunatelly, the viscosity of crude oil is especially temperature-sensitive, leading to the extensive research on porous materials that utilize solar heat for heat generation. In this work, we propose a biodegradable marine bio-based aerogel (PDMS-Ink@CS) with aligned channel structure via directional freeze casting technique, primarily composed of chitosan and cuttlefish ink. The PDMS-Ink@CS demonstrates excellent photothermal conversion and oil adsorption performance. We systematically investigated the effects of sunlight intensity and pore structure on the viscosity-reduction and adsorption rate of crude oil. Under simulated sunlight intensity of 1 kW m−2, the surface temperature of PDMS-Ink@CS aerogel reaches approximately 70 ℃ within 60 s, allowing to absorb crude oil 18 times its weight and recover via extrusion. When combined with a vacuum pump device, the PDMS-Ink@CS aerogel realizes the continuous recovery of crude oil from the seawater surface. Moreover, the separation efficiency of PDMS-Ink@CS aerogel for W/O emulsions can reach 99 %, which greatly broadens its range of applications. Particularly noteworthy is the fact that the PDMS-Ink@CS aerogel biodegrades within 30 days without causing environmental pollution. Thus, this super-hydrophobic ocean biomass-based chitosan aerogel exhibits vast potential for oil spill recovery applications.

Cleanup of oils and organic solvents from contaminated water by biomass-based aerogel with adjustable compression elasticity

Leakage of oils and organic solvents poses a significant threat to aquatic environments. Here, low-temperature carbonized aerogels with highly porous and anisotropic structures obtained only from biomass-derived materials were proposed to absorb polymorphic oils from contaminated water. Specifically, carbonized aerogels prepared at temperatures of 300 °C and 350 °C exhibited ultra-high absorption capacities (40‒125 g g−1) and oil-water separation efficiencies (> 99%) even in harsh environments, which were attributed to their exceptional properties, including high porosity, abundant macropores, excellent thermal stability, and hydrophobicity. Through citric acid crosslinking and low-temperature carbonization, the aerogels exhibited superior compression elasticity and could be cyclically utilized through simple extrusion while realizing the recovery of oils. Moreover, the outstanding photothermal conversion properties obtained through carbonization contributed to the high temperature and fluidity of the oils surrounding the aerogels, which is crucial for improving the absorption performance of high-viscosity oils. Such absorbent materials are used to separate crude oil from oil-water mixtures, which can achieve maximum absorption of 56 g g−1 and increase the absorption rate (from several days to 10 min) in a low-temperature (4 °C) seawater environment.

Sheath-core structured Ca-alginate/PVA aerogel fibers via directed freezing wet-spinning

Biomass-based aerogel fibers have attracted increasing attention due to their renewable nature. However, their disadvantages, such as low mechanical strength, poor long-range order, and easy combustion, are still significant challenges. Herein, a directed freezing-assisted forced stretching strategy is developed to fabricate sheath-core structured Ca-alginate/polyvinyl alcohol (Ca-A/PVA) aerogel fibers with Long-range-ordered pores. The Ca-A/PVA aerogel fibers (3:2 m/m) exhibit the best comprehensive mechanical properties in terms of low thermal conductivity of 0.0524 W·m−1·K−1, a density of 0.1614 g·cm−3, a porosity of 89.9 %, a tensile strength of 8.72 MPa, a tensile modulus of 249.7 MPa, a toughness of 1.98 MJ∙m−3, and a self-extinguishing time from the fire of <1.2 s. The Ca-A/PVA fabrics showed a maximum absolute temperature difference of 11.4 °C at −20 °C and 14.0 °C at 60 °C compared to the plate temperature. The presented strategy is generalizable to other alginate-based aerogel fibers (e.g., alginate/guar gum).

Facile construction of agar-based fire-resistant aerogels: A synergistic strategy via in situ generations of magnesium hydroxide and cross-linked Ca-alginate

Biomass-based aerogel materials have many advantages, such as low thermal conductivity and non-toxicity. These materials are environmentally friendly and have broad development potential in the fields of packaging, cushioning and green building insulation. However, defects, such as low mechanical strength and poor fire safety, greatly limit the application of these materials. In this work, the agar/polyvinyl alcohol composite aerogel modified by the magnesium hydroxide (MH)/sodium alginate (SA) composite flame retardant system was developed by using a freeze-dried technology and the strategy of in-situ generation of MH and crosslinking of SA. The results showed that the MH/SA dramatically enhanced the mechanical and thermal stability of the composites. The compression modulus of AP-M35S15 was 2.37 MPa, which was 152.13 % higher than that of AP-M50. The limiting oxygen index value of AP-M35S15 was 34.1 % and reached V-0 level in the vertical burning test, which was better than those of the samples with a single MH effect. The cone calorimetric test showed that the MH/SA composite flame retardant system performed better in extending the ignition time, slowing down the heat release rate and reducing the total heat release and had a more complete dense carbon structure after burning.

Improving the catalytic and mechanical performance of alginate catalyst through functionalization by aminopolycarboxylic acids.

Biomass-based aerogel catalysts have attracted extensive attention due to their high surface aera, continuous porous and environmental friendliness. However, their catalytic activity and mechanical strength are not satisfied for industrial applications. In this work, to solve the above two issues, a new kind of graphene oxide enhancediminodiacetic acid-functionalized Cu-cross-linked alginate (GO-Cu-SA-IDA) aerogel composites were prepared. The physicochemical property of the prepared alginate aerogel composites was characterized systematically, and their catalytic activities were studied in the hydroxylation of phenol. Results illustrated that compared with Cu-SA aerogels (∼16%), the amount of loaded copper ion which played as the active sites in GO-Cu-SA-IDA aerogel composite was increased by 2 times (32.2%). In addition, the mechanical strength of GO-Cu-SA-IDA was increased by 10 times. After functionalization, both the catalytic activity and mechanical strength of prepared alginate aerogel composites were enhanced successfully. In addition, the catalyst had been recycled five times with only 5.8% loss of its catalytic activity, which provided a desirable material for next generation of catalysts.

One-step synthesis of Enteromorpha graphene aerogel modified by hydrophilic polyethylene glycol achieving high evaporation efficiency and pollutant tolerance

Photothermal evaporation using solar energy is a sustainable way to produce fresh water from seawater. Aiming to explore functional materials as a solar-energized evaporator with enhanced evaporation rate and pollutant tolerance, this study was to synthesize a self-floating composite graphene aerogel (GA) doped with Enteromorpha and modified polyethylene glycol (PEG), named as PEGA using solar energy for desalination. Physio-chemical properties and evaporative mechanism of PEGA were experimentally investigated and analyzed with respect to molecular weight, PEG dosage, and ratio of Enteromorpha and graphene oxide. Experimental data revealed that the modification of PEG improved hydrophilic functional ability of PEGA, resulting in increasing the evaporation rate and photothermal conversion efficiency up to 2.55 kg/(m2·h) and 105.71 %, respectively. The ion removal rate of seawater exceeds 99.99 % via the PEGA conducted solar evaporation. Furthermore, PEGA possessed an excellent property of salinity emulsion pollution tolerance. Particularly, the evaporation rate of the PEG-modified biomass-based aerogel was 2.84 kg/(m2·h) in a 15 wt% NaCl solution (1 sun, 6 h) and 2.50 kg/(m2·h) at 1 h. The formation of hydrogen bonds between –OH of PEG and water molecules assist to conduct water along the graphene matrix to improve water evaporation. The cost of the graphene aerogel modified by Enteromorpha was reduced by 38.88 % less than the original graphene aerogel. The results from this study will greatly promote the application of graphene aerogel for desalination via solar evaporation.

Scalable manufacturing of light, multifunctional cellulose nanofiber aerogel sphere with tunable microstructure for microwave absorption

Thanks to the high strength-to-weight ratio and aspect ratio, large specific surface area, and sustainability, cellulose nanofibers (CNFs) have incomparable advantages in constructing multifunctional aerogels. However, efficient utilization of the nanofibrous microstructure for developing aerogels of high-performance is extremely challenging due to the severe agglomeration of CNF. Here, a novel type of ultralight aerogel spheres composed of fibrous or sheet-like CNF-derived nanocarbon are manufactured via a facile, scalable drop-freezing followed by a pyrolysis approach. The nanostructured carbons of tunable morphologies are accomplished, endowing the aerogel spheres with abundant hierarchical pores, large specific surface area, and three-dimensional conductive skeletons with ultralight nature. In addition to the high-efficiency adsorption of the organic dye, the aerogel spheres enable a controllable and excellent electromagnetic wave absorption. The aerogels composed of coexisting fibrous and layered nanocarbons display an effective absorption bandwidth of 6.16 GHz, and a minimum reflection loss of −66.3 dB at the thickness of 2.14 mm, and a merely 1 wt% filler loading, which significantly outperforms that of other carbon-based absorbers. This work thus suggests a new avenue for designing high-performance, sustainable multifunctional biomass-based aerogels, demonstrating extensive application potentials in adsorption, electromagnetic absorption, and aerospace.