As-prepared Aerogels Research Articles

Hydrosilylation Adducts to Produce Wide-Temperature Flexible Polysiloxane Aerogel under Ambient Temperature and Pressure Drying.

Despite incorporation of organic groups into silica-based aerogels to enhance their mechanical flexibility, the wide temperature reliability of the modified silicone aerogel is inevitably degraded. Therefore, facile synthesis of soft silicone aerogels with wide-temperature stability remains challenging. Herein, novel silicone aerogels containing a high content of Siare reported by using polydimethylvinylsiloxane (PDMVS), a hydrosilylation adduct with water-repellent groups, as a "flexible chain segment" embedded within the aerogel network. The poly(2-dimethoxymethylsilyl)ethylmethylvinylsiloxane (PDEMSEMVS) aerogelis fabricated through a cost-effective ambient temperature/pressure drying process. The optimizedaerogel exhibits exceptional performance, such as ultra-low density (50mg cm-3), wide-temperature mechanical flexibility, and super-hydrophobicity, in comparison to the previous polysiloxane aerogels. A significant reduction in the density of these aerogels is achieved while maintaining a high crosslinking density by synthesizing gel networks with well-defined macromolecules through hydrolytic polycondensation crosslinking of PDEMSEMVS. Notably, the pore/nanoparticle size of aerogels can be fine-tuned by optimizing the gel solvent type. The as-prepared silicone aerogels demonstrate selective absorption, efficient oil-water separation, and excellent thermal insulation properties, showing promising applications in oil/water separation and thermal protection.

Flame retardant, heat insulating and hydrophobic chitosan-derived aerogels for the clean-up of hazardous chemicals

Leakage of hazardous chemicals often causes significant casualties, enormous economic losses, and negative social benefits. Presently, fire rescue personnel lack efficient and eco-friendly disposal materials for hazardous chemical leakage accidents. In this study, chitosan (CS) aerogels with excellent flame-retardant performance were prepared via cross-linking by two phosphorus-containing vanillin-based compounds (DV and TV). The as-prepared chitosan aerogels were lightweight and porous. The introduction of DV and TV greatly enhanced the residual char yields of CS at 700 °C and the flame-retardant performance of chitosan aerogels. TCS-5.0 possessed the best flame-retardant performance, indicating that TV was more effective than DV in enhancing the flame-retardant performance of chitosan aerogels. The greatly improved flame-retardant properties could be attributed to TV effectively promoting the residual char formation of chitosan aerogels and reducing the formation of combustible gas phase products. To improve the hydrophobicity of chitosan aerogels, TCS-5.0 was treated with solution immersion to load siloxane molecules on its surface. The water contact angle of HTCS-5.0 was 136.1°. HTCS-5.0 had a high oil absorption multiplicity, absorbing up to 31 times its own weight of chloroform. HTCS-5.0 could continuously absorb organic solvents on the water surface with the assistance of a vacuum pump, indicating that HTCS-5.0 could be used for the clean-up of hazardous chemical leakage accidents.

Facile Preparation of a Novel HfC Aerogel with Low Thermal Conductivity and Excellent Mechanical Properties.

Aerogels emerge as captivating contenders within the realm of high-temperature thermal resistance and thermal insulation. Nevertheless, their practical applications are usually constrained by their inherent brittleness when subjected to rigorous conditions. Herein, employing hafnium dichloride oxide octahydrate (HfOCl2·8H2O) as the hafnium source and resorcinol-formaldehyde (RF) as the carbon precursor, hafnium carbide (HfC) aerogels are fabricated via the sol-gel method complemented with carbothermal reduction reaction. Investigations are conducted into the effects of various molar ratios, duration, and temperatures of calcination on the microstructural features and physico-chemical characteristics of the as-prepared HfC aerogel. The aerogel shows a high BET-specific surface area (601.02 m2/g), which is much larger than those of previously reported aerogels. Furthermore, the HfC aerogel exhibits a low thermal conductivity of 0.053 W/(m·K) and a compressive strength of up to 6.12 MPa after carbothermal reduction at 1500 °C. These excellent thermal insulation and mechanical properties ensure it is ideal for the utilization of high-temperature thermal resistance and thermal insulation in the fields of aerospace.

Fabrication of physically multi-crosslinked sodium alginate/carboxylated-chitosan/montmorillonite-base aerogel modified by polyethyleneimine for the efficient adsorption of organic dye and Cu(II) contaminants

Efficient removal of contaminants, like heavy metal ions and dyes, from wastewater by eco-friendly and low-cost adsorbent is highly desirable. Herein, a green aerogel was prepared using sodium alginate/carboxylated chitosan/montmorillonite (MSC-P) as the basic framework, followed by polyethyleneimine functionalized and Ca2+ post-crosslinking. The multi-crosslinked aerogel exhibited the excellent adsorption capacity towards methylene blue (MB), Congo red (CR) and Cu(II), with the qm being 723.97 mg/g, 1573.21 mg/g and 203.99 mg/g, respectively. The mathematical model suggested that the adsorption process for MB fitted pseudo-first-order kinetics model better, whereas the CR and Cu (II)’s adsorption process were conformed to pseudo-second-order kinetics model. Moreover, the adsorption isotherm for three contaminants could be well described by Langmuir model, suggesting that the adsorption process was spontaneous and mainly controlled by monolayer coverage. Moreover, MSC-P aerogel exhibited good reusability as the removal efficiencies for MB and Cu(II) were 85.16 % and 51.4 % after ten cycles of adsorption–desorption, respectively. Importantly, it possessed considerable simultaneous removal ability for binary system mixed dyes. In combination of FTIR analyses, it was found that electrostatic attraction, hydrogen bonding, coordination and cation exchange were the main adsorption mechanisms involved. Therefore, the as-prepared aerogel can be considered as a promising adsorbent for the treatment of wastewater.

Lignocellulose/chitosan hybrid aerogel composited with fluorescence molecular probe for simultaneous adsorption and detection of heavy metal pollutants

The pollution of heavy metals to aquatic ecosystem is getting more and more attention. Therefore, there is an urgent need to develop a low-cost, high-efficient, high-selective and environmental adsorbing material that can simultaneously indicate and adsorb heavy metal ions. Cellulose-based aerogel has attracted much attention due to its strong adsorption capacity, good biodegradability and cost performance. In this paper, cellulose nanofiber/chitosan/polyvinyl alcohol/lactam Rhodamine 6 G composite aerogel (CNF/CS/PVA/SRh6G) was prepared by freeze-drying technology with CNF/CS hybrid aerogel as adsorbent skeleton, SRh6G as fluorescent probe and PVA/glutaraldehyde (GA) as crosslinking agent. When the volume ratio of CNF suspension to CS solution was 10:1, as-prepared composite aerogel had a lower density (145.92 mg/cm3) and a higher specific surface area (0.04293 cm3/g). It also exhibited excellent superhydrophilicity and superoleophobicity underwater (OCA-159°), the underwater OCA of which always kept larger than 150° in the surroundings with pH of 1–14. Therefore, CNF/CS/PVA/SRh6G composite aerogel owned good acid and base resistance, which could be applied to rapid adsorption and real-time detection of metal ions (Hg2+, Ag+, Al3+, Fe3+ and Cu2+) in wastewater. CNF/CS/PVA/SRh6G composite aerogel could display obvious color and fluorescence variations under sunlight and ultraviolet light, and present the good reversibility after regeneration via base solution (pH=14). Under water, such CNF/CS/PVA/SRh6G composite aerogel showed a good compression elasticity with the maximum pressure of 26.2 N. After five cycles, the adsorption of composite aerogel still could reach up to 19 times of its own weight. Results also showed that it had remarkable durability and structural stability, indicating its broad application prospects in the field of wastewater treatment.

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.

Carbon coated vermiculite aerogels by quick pyrolysis as cost-effective and scalable solar evaporators

Purification of seawater and wastewater by solar-driven interfacial evaporation is a promising way to alleviate water scarcity. However, the high cost, complex fabrication methods, and short service life of the materials limit their practical application. Herein, a novel three-dimensional (3D) photothermal aerogel composited of vermiculite nanosheets and polyvinyl alcohol (PVA) precursors have been prepared via freeze-drying and treated by quick pyrolysis for highly efficient solar-driven interfacial evaporation. The vermiculite nanosheets exfoliated from natural clay were used as the skeletal support of the composite aerogels, which are cheap and abundant natural materials. The introduced PVA improves the mechanical properties and produces carbon derivatives after pyrolysis, enhancing the light absorption capacity. The as-prepared aerogels have hierarchical porous structures, impressive mechanical properties, great light absorption capacity, and outstanding salt-rejection ability. The optimized aerogel not only exhibits a high evaporation rate of 2.64 kg m−2 h−1 (normalized to top and side surfaces) under 1.0 sun irradiation with excellent cost-effectiveness at 361.64 g h−1 $−1 but also shows superior performance in treating high-salt (15.0 wt%) brine water and organic dye-contained wastewater. The proposed method provides an attractive and effective way to prepare photothermal aerogels for efficient solar steam generation for mitigating water scarcity issues.

Highly Transparent, Temperature-Resistant, and Flexible Polyimide Aerogels for Solar Energy Collection.

Advanced aerogel materials with low thermal conductivity and high transparency have shown great application prospects in the solar thermal energy conversion field. However, most aerogels do not meet these requirements due to their low optical transparency and poor mechanical properties. To tackle this problem, we have created versatile polyimide (PI) aerogel materials by adjusting the monomers to alter their molecular structure. These materials exhibit exceptional thermal insulation properties and high transparency, making them ideal for use in the construction of efficient solar collector devices. Incorporating 1,3,5-benzenetricarbonyl trichloride into PI aerogel results in high strength (>3 MPa) and excellent transmittance (>90%) over a broad range of wavelengths (500-2650 nm). The as-prepared PI aerogel solar collector (PIASC) also exhibits a low thermal conductivity (0.032 W/mK), a low density (0.1 g/cm3), and high porosity (90%). By changing the shape of the collector from a flat plate to a cylindrical ring, the heat collection efficiency and capacity are significantly improved, resulting in efficient heat collection. The circular ring collector has a maximum heat collection temperature of 236.8 °C. The PIASC, which is both flexible and highly transparent, is an ideal candidate for advanced optical elements and solar collectors.

A facile strategy for constructing lightweight, fire safety and compression resistance poly(vinylalcohol) aerogels with highly-efficient expansible graphene oxide/layered double hydroxides hybrid synergistic flame retardant

Poly(vinyl alcohol) (PVA) aerogels with excellent environmentally friendly properties have been considered to replace undegradable polymer foams. However, due to highly flammable, hydrophilic, and worse compression resistance performance, PVA aerogels have always been excluded from practical. Herein, a fire safety and compression resistance PVA/expansible graphene oxide (EGO)/Layered double hydroxides (LDHs) (PGL) aerogel was prepared via the freeze-drying method and electrostatic adsorption of flame retardant. The ice crystals from aerogels were sublimated and left a mass of tree-like pore tunnel structures. Meantime, the compound of EGO and LDHs rendered PGL aerogels high compressive strength of 6.0917 MPa (at 80% of strains), a high specific modulus of 19.16 m2/s2, and an ultra-low density of 0.059 g/cm3. Especially, the as-prepared PGL aerogels showed heat release reduced by 55.4%, smoke release reduced by 54.3%, and the limiting oxygen index reaching up to 31%. Moreover, LDHs also enhanced the interface with PVA/EGO resulting in hydrophobic performance improvement. The proposed enhancements mechanism suggested that (i) chemical reactions between EGO and PVA matrix; (ii) a mass of negative potential sites from the interface of PVA/EGO composites made LDHs sheets easily adsorbing; (iii) oxygen-containing groups from EGO and LDHs absorbed mass of heat during combustion; (iv) the compact char residues on the surface of aerogels acting as barriers suppressed smoke and prevented PVA matrix from further combustion. Therefore, electrostatic adsorption as a facile production process was paved for meeting the compression resistance, flame-retardant, heat-insulating, and smoke-suppressed requirements of PVA aerogels in this work.

Sustainable, decentralized water treatment system fabricated from domestic waste materials and ultrafast-reduced graphene oxide

The demand for fresh water will increase in the coming decades as the world population grows. While large-scale water purification plants will serve highly populated areas, the demand of fresh water will continue to grow even in remote and potentially under-developed locations. In this work, it has been shown that fresh water can be produced from seawater or polluted water using waste paper and direct solar exposure, without the need of electricity during water purification. The highly efficient solar evaporation system proposed here, which is based on graphene/cellulose aerogels, can be fabricated quickly without highly technical skills, requiring only a microwave oven, graphene oxide samples, and cellulose fibers obtained from packaging (i.e., waste paper and polyethylene foams). The produced aerogels show high photo-thermal conversion, excellent hydrophilicity and low thermal conductivity, properties that are conducive to evaporation rates as high as 1.83 kg m−2 h−1, photo-thermal efficiency of 92%, and stability for more than 40 operation cycles. Despite using waste materials, these performance metrics are superior to those reported for most materials to date, and are a consequence of the manufacturing process described here. Field tests confirmed that 1 m2 of the as-prepared aerogels can produce between 6.44 and 11.27 kg of fresh water from seawater or polluted water in a 12-hour period, which is the daily amount of drinking water required for three adults based on World Health Organization projections.

High mechanical flexible and recyclable organic-inorganic hybrid polyhexahydrotriazine aerogel for oil/water separation

Oily wastewater and light crude spills are great threats to the environment and human health, polymeric porous materials for oil/water separation is a very effective method to reduce environmental pollution and protect human health. Herein, we design recycle, super-hydrophobic, and mechanically flexible silicone-based polyhexahydrotriazine (Si-PHT) aerogel for efficient oil/water separation, hexanediamine-based polyhexahydrotriazine (HDA-PHT) is also designed for parallel comparison. The Si-PHT and HDA-PHT aerogels are obtained via the cross-linking reaction between diamine and formaldehyde, followed by the atmospheric drying without any additional post-processing. The as-prepared Si-PHT aerogel shows excellent hydrophobicity (water contact angle of 154.19°). Moreover, the adsorption capacity of Si-PHT aerogel for oil or organic solvent is 22.6–40.5 times of its own weight. More importantly, the Si-PHT aerogel could be compressed to 50% of its original size with outstanding high compress strain (554.3 kPa). The major raw material for synthesis of Si-PHT and HDA-PHT aerogels are readily recoverable and further recycle. This work provides a simple prepared and recyclable porous material for oil/water separation, and a rationally designed Si-PHT aerogel shows great potential for practical applications in the treatment of oily wastewater.

Designing underoil superhydrophilic ultralight core-shell nano porous carbon aerogel for efficient gravity-directed separation of water-in-oil emulsions with high flux

Oily wastewater has caused serious environmental and biological issues, to overcome this problem, various materials have developed. In this perspective, herein, we report the preparation of a nanoporous carbon aerogel (NPCA)@carbon (C) NPs aerogel through a core-shell growth method. It is interesting to note that in this study, we introduce a new procedure to remove δ-Al2O3 NPs without using any alkaline media. In the other word, NPCA is not only a great candidate to use as a template for growing the NPCA@carbon (C) NPs aerogel, but also has an excellent ability to remove the formed δ-Al2O3 NPs only by heat treatment, which is the first example in this area, to the best of our knowledge. Importantly, the integration of two layers of carbon in one particle at the nanometer level in the structure of NPCA@C NPs aerogel leads to achieving a structure with an average size of 13–51 nm, hierarchical porous structures, low density (3.7 mg/cm3), high porosity (99.83%), large specific surface area (946.75 m2/g) and superhydrophibicity underoil behavior. The as-prepared aerogel was found to be an excellent sorbent to rapidly separate both surfactant-free and surfactant-stabilized water-in-oil emulsions by gravity with high separation efficiencies up to 99.9% and, the filtration fluxes up to ∼ 4000 L m−2 h−1. Notably, the aerogel mentioned above exhibited excellent separation performance even after 40 recycle runs without a discernible decrease in its separation efficiency (99.94%).

Ambient-drying to construct unidirectional cellulose nanofibers/ carbon nanotubes aerogel with ultra-lightweight, robust, and superior microwave absorption performance

Microwave absorption materials (MAMs) with lightweight wide effective absorption band, superb mechanical performance, and capable of large-scale preparation are highly desirable for dealing with microwave pollution, but it is still a challenge to realize these performances simultaneously on one material. Herein, we report an ambient drying and non-chemical cross-linking way of preparing high-performance microwave absorption aerogels from cellulose nanofibers (CNF) and carbon nanotubes (CNT). Anisotropic aerogel pore walls with excellent mechanical properties can be constructed by unidirectional cycling freeze-thaw to cross-linking CNF and CNT. During this process, a sustainable bioinspired dual-networks interpenetrating strategy is constructed by benefiting from the mono-dispersion of CNF and CNT, thus enabling the creation of hybrid dual-networks of hydrophobic/hydrophilic nanofibers. Impressively, it is found that the dual-networks induced anisotropic aerogel structure and dense pore walls can synergistically result in favorable mechanical properties. In detail, aerogels with tunable ultralow densities (0.0262–0.0296 g cm−3), high mechanical properties (the stress of the sample reaches up to 329.8 kPa at 75% strain) and low shrinkage (∼10%) can be prepared. Besides, the aerogels behave a large-scale production future (diameter of aerogel up to 9.24 cm). The as-prepared aerogel delivers a remarkable minimal reflection loss (RLmin) of −60.22 dB at 13.012 GHz and a wide effective absorption bandwidth (EAB) from 2.163 to 18 GHz (15.84 GHz) at a thin thickness of 7.46 mm, which covers almost all the S, C, X, and Ku bands. This work provides a strategy to prepare lightweight and efficient microwave absorbers, as well as illustrates good impedance matching and moderate dielectric loss capability.

Core-shell FeCo@carbon nanocages encapsulated in biomass-derived carbon aerogel: Architecture design and interface engineering of lightweight, anti-corrosion and superior microwave absorption

The development of multifunctional microwave absorbing materials for practical applications in complex environments is a challenging research hotspot. Herein, the core–shell structure FeCo@C nanocages were successfully anchored on the surface of biomass-derived carbon (BDC) from pleurotus eryngii (PE) via freeze-drying and electrostatic self-assembly process, achieving lightweight, anti-corrosive, and excellent absorption properties. The superior versatility benefits from the large specific surface area, high conductivity, three-dimensional cross-linked networks, and appropriate impedance matching characteristics. The as-prepared aerogel realizes a minimum reflection loss (RLmin) of −69.5 dB with a corresponding effective absorption bandwidth (EAB) of 8.6 GHz at 2.9 mm. Simultaneously, the computer simulation technique (CST) further proves that the multifunctional material can dissipate microwave energy in actual applications. More importantly, the special heterostructure of aerogel endows excellent resistance to acid, alkali, salt medium, allowing potential applications of the microwave absorbing materials under complex environmental conditions.

Controllable Epitaxial-like Growth of Bi2S3/MoS2 Hybrid Aerogel Nanostructures for Sensitive NO2 Detection at Room Temperature

Constructing heterogeneous interfaces on a nanoscale that can prominently improve the gas-sensing properties has been comprehensively reported. However, the effect of parallel heterostructures formed by unique synthetic means on nitrogen dioxide room-temperature sensing properties still needs to be clarified, which hinders the development of heterostructured hybrid materials in the field of gas sensing. In this study, large-sized MoS2 was parallel-wrapped on the surface of nanoscale Bi2S3 rods, and then, the Bi2S3/MoS2 nanocomposite aerogels were formed by freeze drying and calcination. The NO2 sensing performance of the hybrids and possible surface processes at room temperature have been investigated and deduced. The as-prepared nanocomposite aerogels (Bi2S3/MoS2-2) exhibited a larger specific surface area, a mass of active defect sites, and a higher charge density, thus possessing 15- and 20-times higher response than that of pristine MoS2 nanosheets and Bi2S3 nanorods, respectively. This study provides an efficient way to synthesize large-area parallel heterostructures between two bis-sulfides (Bi2S3 and MoS2), leading to excellent NO2 gas sensing performance.

Ultra-broadband electromagnetic wave absorbent: In-situ generated silica modified conductive carbon fiber aerogels

The research and development of dielectric microwave absorbing materials with broad electromagnetic (EM) response is a significant project in EM wave absorption field. To achieve high-performance absorption and strong interfacial bonding at the same time, thermal-assisted in-situ bonding technology was applied to fabricating the dielectric composite absorbing materials. Thanks to the combination of vacuum filtration and in-situ hydrothermal reaction, the as-prepared binary composite aerogel shows both strong interface contacting and good mechanical stability. In addition, the carbon nanofibers/silica composite aerogel (CSA) exhibits ultra-broad effective bandwidth covering from S to Ku band, originated from the uniform dispersed silica aerogel in conductive carbon fiber network. In details, for CSA1 sample, the maximum reflection loss (RL) values and effective absorption bandwidth reach −46.2 dB (1.8 mm) and 5.2 GHz (1.5 mm). Meanwhile, the optimum RCS reduction values reaches 16.2 dB m2 when the detection theta was set as 0°. For CSA2 sample, the effective absorption bandwidth reaches 8.64 GHz at 1.5 mm, and tends to possess lower frequency EM response covering the S-band. This work exhibits a kind of broad-bandwidth aerogel absorbers at low thickness, which shows huge potential in large-scale production of microwave absorbing devices.

Development of corn-stalk based aerogel for selective removal of oil from water

The recurrent oil spillage owing to natural processes or oil transportation in marine bodies causes substantial environmental problems and aquatic life damage. In this regard, the present work envisages preparing an aerogel using waste corn-stalk as the base material. The synthesis method is easy, cost-effective, and scalable. The prepared aerogel is ultra-lightweight and possesses low density, high surface area, and porosity. Further, the water contact angle of the prepared aerogel is 142.5°. The oil sorption studies revealed that the maximum oil sorption capacity of the prepared aerogel is 28 g/g. The oil sorption kinetic study revealed that experimental data of oil sorption follows second-order kinetics. Moreover, the aerogel possesses recyclability, as seen from the oil sorption capacity of 15.22 g/g after five cycles. Furthermore, it could uptake other organic solvents with appreciable sorption capacity, thus the as-prepared aerogel can be used for the selective removal of different organic solvents from water.

Facile synthesis of a novel Zn2Ti3O8 aerogel with porous structure for high-efficient degradation of antibiotics under simulated sunlight

Photocatalytic degradation, as advanced oxidation methods with high efficiency and good stability, is considered a promising method to alleviate antibiotic pollution. Herein, we prepared a novel Zn2Ti3O8 aerogel by a simple sol-gel method based on the advantages of the abundant pore structure of aerogel material and the high photocatalytic activity of zinc titanate. The Zn2Ti3O8 aerogel shows a typical homogeneous structure and low band gap width (3.32 eV), which could achieve photogenerated carrier separation and transfer under simulated sunlight. The material has high specific surface area (120.1 m2/g) and abundant pore structure, which can provide multiple diffusion channels for pollutant molecules and generate massive reactive sites. In the absence of cocatalysts, the prepared Zn2Ti3O8 aerogel can achieve more than 95% degradation efficiency for 50 mg/L of ofloxacin (OFL) contaminated solution in 60 min. Electrochemical impedance spectroscopy (EIS) and transient photocurrent test results display that Zn2Ti3O8 aerogel exhibits the highest photocurrent density and lower charge transfer resistance. Meanwhile, the results of density functional theory (DFT) are consistent with the characterization results of electron spin resonance (ESR). The ·OH and ·O2− generated in the catalytic reaction could attack OFL molecules from different regions to achieve the purpose of decomposition. We believe that the as-prepared Zn2Ti3O8 aerogels are expected to be used in the practical treatment of catalytic degradation of OFL and other antibiotic pollutants.

A sustainable layered nanofiber/sheet aerogels enabling repeated life cycles for effective oil/water separation

Discarded oil-containing absorbents, which has been used in handling oil spills, are tricky to deal with and have rose global environmental concerns regarding release of microplastics. Herein, we developed a facile strategy to fabricate sustainable absorbents by a gas-inflating method, through which 2D electrospinning polycaprolactone nanofiber membranes were directly inflated into highly porous 3D nanofiber/sheet aerogels with layered long fiber structure. The membranes were inflated rapidly from a baseline porosity of 81.98% into 97.36–99.42% in 10–60 min. The obtained aerogels were further wrapped with -CH3 ended siloxane structures using CH3SiCl3. This hydrophobic absorbent (CA ≈ 145°) could rapidly trap oils from water with sorption range of 25.60–42.13 g/g and be recycled by simple squeeze due to its mechanical robustness. As-prepared aerogels also showed high separation efficiency to separate oils from both oil/water mixtures and oil-in-water emulsions (>96.4%). Interestingly, the oil-loaded absorbent after cleaning with absolute ethanol could be re-dissolved in selected solvents and promptly reconstituted by re-electrospinning and gas-inflation. The reconstituted aerogels were used as fire-new oil absorbents for repeated life cycles. The novel design, low cost and sustainability of the absorbent provides an efficient and environmentally-friendly solution for handling oil spills.

Highly robust separation for aqueous oils enabled by balsa wood-based cellulose aerogel with intrinsic superior hydrophilicity

Owing to the strong adsorption capacity, cellulose aerogel has emerged as a promising material in the field of oil–water separation. In this study, we have taken advantage of the inherent superior hydrophilicity of balsa wood-based cellulose aerogel for the separation of various aqueous oils. A facile approach to preserve inherent hydrophilic cellulose nanofibers was achieved by removing lignin and hemicellulose fractions from natural wood, resulting in flexible cellulose aerogel with lamellar architecture. As a result, the separation efficiency of cellulose aerogel can achieve 99.97% for immiscible aqueous oils, and 98.45% even for water-in-oil emulsions. Moreover, the as-prepared cellulose aerogel exhibits remarkable mechanical properties, with stress decay of 7% after 60 compression cycles making it recycle feasible. When exposed to several complex environments including acid, alkaline and salt for a long time, the cellulose aerogel remains stable superoleophobicity with underwater oil contact angle of 153.2 ± 1.2°. Given the low operating cost, high separation efficiency and durability and stability of cellulose aerogel, this work provides a promising material for aqueous oils purification.