Pure Aerogel Research Articles

Flexible, Strong, Multifunctional Graphene Oxide/Silica-Based Composite Aerogels via a Double-Cross-Linked Network Approach.

Multifunctional silica-based aerogels are an emerging material due to their unique properties and wide applications. However, their large-scale production and application are limited due to the high cost and cumbersome preparation process. Herein, we prepare graphene oxide (GO)/silica-based composite aerogels via a simple in situ sol-gel reaction. GO nanosheets (GOs) are functionalized with polyethylenimine (PEI) and 3-glycidyloxypropyltrimethoxysilane (GPTMS) successively. After a cohydrolysis and condensation of trimethoxymethylsilane (MTMS) and dimethoxydimethylsilane (DMDMS) in the presence of GOs and a convenient ambient-pressure drying process, the composite aerogels are obtained. In addition to the normal cross-linking of MTMS and DMDMS, the GOs also behave as cross-linking points to significantly enhance the mechanical properties and thermal stability of the network of the composite aerogels. The pore structure of the aerogels is tailored by varying the GO loads as well as its surface modification. The Young's modulus of a composite aerogel with a GO load of 0.5 wt % is about 5 times that for a neat polysiloxane aerogel, and the maximum degradation rate temperature is increased to over 90 °C. Compared with pure polysiloxane aerogel, the thermal insulation and flame resistance are also improved by a small addition of GOs. Moreover, GO/silica-based composite aerogels show stable piezo-resistive behavior. With the excellent mechanical properties, thermal stability, and multifunctionality, GO/silica-based composite aerogels show promising applications under some harsh and extreme conditions.

Structural analysis of embedding polyethylene glycol in silica aerogel

Embedding of the functional materials into aerogel powders was realized via the filtration method. In this work, the effect of aerogel on the molecule structure of the embedded polyethylene glycol (PEG) was investigated by dispersing aerogel powders in 20 wt% PEG aqueous solution with subsequent filtration method. The encapsulation of the PEG in the aerogel was characterized by isothermal nitrogen (N 2 ) adsorption/desorption. The structure of the embedded PEG in the aerogel powders was investigated via SEM-EDS, FE-SEM, FT-IR, XRD. TG-DTA, DSC, and leakage test. It was found that the only physical capillary force worked to adsorb PEG molecules from its solution by the aerogel powders. The BET surface area and the DFT pore volume of the PEG/aerogel powders were reduced obviously when compared with pure aerogel powders. The ability of the pores in the aerogel powders ranging from 14 nm to 16 nm to adsorbing the PEG molecules from the water system was weak. The crystallinity of the PEG was significantly reduced because of the limited space for crystal growth, and the decomposed temperature and thermal capacity decreased correspondingly. • Selective adsorption of PEG by pores in aerogel. • Space limitation of PEG crystal growth in aerogel. • Stable thermal property of PEG/aerogel powders.

Novel Nanocellulose/Polymer Composite Aerogel as Solid‐State Fluorescence Probe by Pickering Emulsion Route

AbstractIn this study, cellulose nanofibrils (CNF)/polymer (nonwater soluble) composite aerogels are facilely fabricated using CNF‐stabilized Pickering emulsion gel technology combined with the freeze‐drying method. Pior to the formation of the O/W Pickering emulsion stabilized by the CNF, a nonwater‐soluble polymer, such as polymethyl methacrylate, polylactic acid (PLA), polycabonate, polystyrene, and so on, is dissolved into the oil phase, and the CNF are effectively dispersed in the water phase. The subsequent gelation of the Pickering emulsion through ultrasonic emulsification followed by freeze‐drying is carried out to obtain the CNF/polymer composite aerogels. The obtained CNF/polymer with a low density of ≈0.01g cm−3 have better dimentional stability and mechanical properties compared with the pure CNF aerogel. Additionally, 1,4‐dihydroxyanthraquinone (1,4‐DHAQ, a fluorophore) is loaded into the A‐CNF/PLA composite aerogel by dissolving it along with PLA into the oil phase to form a novel solid‐state fluorescence probe for Cu2+ detection with an extremely low detection concentration of 10−8 mol L−1. Interestingly, neither solvent exchange nor chemical reaction (or polymerization) is required in the preparation of aerogels. This study provides a facile and universal route for the fabrication of CNF/polymer composite aerogels and the development of their functional products.

Porphyrin-sensitized quasi-solid solar cells with MOF composited titania aerogel photoanodes

ZnTPP-COOH porphyrin-based quasi-solid dye-sensitized solar cells were fabricated with the following three different photoanode materials: Ni-MOF@titania aerogel composite, Cu-MOF@titania aerogel composite, and pure titania aerogel. Their photovoltaic performances were investigated through photocurrent–photovoltage (J–V) curve, electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent spectroscopy, and transient measurements of photocurrent and photovoltage decay. Among the three cells, the enhancement of photocurrent is observed in cells containing Ni-MOF@titania aerogel photoanodes. As a result, the Ni-MOF@titania aerogel photoanode–based cell achieved the highest photocurrent density of 8.88 mA/cm2 and power conversion efficiency of 2.34%. This value is higher than that of the other two devices. Moreover, the EIS analysis is used to understand better the possible electron transfer behind the photocurrent boosting in Ni-MOF@titania aerogel photoanode–based cell. Low Rct value (44.1 Ω) and low τd value of the Ni-MOF@titania aerogel device are the key factors to improve the electron flow, the Warburg diffusion of electrolyte, as well as the regeneration process. These factors are attributed as the reason for their best performance among other devices. Based on the results obtained, the plausible mechanism for electron transfer is discussed using the energy level cascades of TiO2/MOF/porphyrin dye. The transient measurements indicated that the devices exhibited good reproducibility under multiple illuminations.

Solvent-free nanoalumina loaded nanocellulose aerogel for efficient oil and organic solvent adsorption

HypothesisCellulose-based aerogel, due to its rich reserves, environmental friendliness and porous structure, is considered as a new type of adsorbents for treating oil and water pollution. However, the functionalization of cellulose aerogel is still required for the efficient increase of its adsorption performance in wide applications. The combination of nanomaterials could significantly improve the adsorption capability of nanocellulose aerogel. ExperimentsIn this work, nanocomposite aerogels comprising of nanocellulose and nanoalumina (NC/Al2O3) are produced via a solvent-free method and the effect of weight ratios between nanocellulose and nanoalumina on the adsorption properties of NC/Al2O3 aerogels has been studied. FindingsThe results reveal that the NC/Al2O3 aerogel with a low density of 5.1 mg cm−3 could obtain the optimal pore microstructures and the highest oil and organic solvent adsorption capacities with the preparation condition under the nanocellulose/nanoalumina weight ratio of 1:0.25 and 0.4 wt% of nanocellulose in aqueous solution. The presence of nanoalumina facilitates the change of microstructure morphologies, the increase of BET specific surface area and the adsorption capacities of NC aerogel. Compared with pure NC aerogel (74.07 ± 1.67, 69.87 ± 1.01, 81.21 ± 3.20, 52.07 ± 1.70, 48.49 ± 1.01, 75.45 ± 3.58 and 87.03 ± 0.46 g g−1 for thiophene, anhydrous ethanol, ethyl acetate, cyclohexane, sesame oil, acetone and dichloromethane, respectively), the NC/Al2O3 aerogel manifests an outstanding adsorption capacity (108.07 ± 0.37, 89.91 ± 4.83, 93.93 ± 3.81, 71.13 ± 2.48, 64.83 ± 2.25, 85.19 ± 3.87 and 117.65 ± 5.68 g g−1, accordingly). By considering the desirable performance features and the convenient fabrication approach, this nanocellulose nanocomposite aerogel might be a feasible alternative for oily waste water recovery and conservation of environment.

Facile fabrication of an effective nanocellulose-based aerogel and removal of methylene blue from aqueous system

Water pollution caused by organic dyes is becoming a critical global environmental concern. Here, we designed a novel and green aerogel by freeze-drying composed of cellulose nanofibril (CNF) and graphene oxide-silica (GO-silica), which could efficiently remove organic dyes from contaminated water and solve the recycle of nanohybrid materials. Subsequently, the as-synthesized aerogels were evaluated for the adsorption of methylene blue (MB) form aqueous solution. The results showed that GO-silica particles were synthesized successfully and displayed a low degree of crystallinity. And compared to pure CNF aerogels, the composite aerogels exhibited superior adsorption performances, with the maximum value of 608.4 mg/g. Furthermore, the adsorption kinetic and isotherm MB on the composite aerogels obeyed the pseudo-second-order and the Langmuir model, respectively. The Langmuir model fitting yielded a maximum adsorption capacity of 623.9 mg/g for MB. According to the results of the mean free energy (E) and the Elovich isotherm model, the decolorization applying CNF and composite aerogels was occurred chemically. This aerogel introduced here is easy to fabricate, efficient, and biodegradable, which makes it a potential alternative for wastewater treatment.

Fabrication of bimetallic Hofmann-type metal-organic Frameworks@Cellulose aerogels for efficient iodine capture

Abstract It is of great significance to capture radioiodine from nuclear-related activities. Herein, We fabricated two kinds of hybrid aerogels composed with bimetal Hofmann-type metal-organic frameworks (Co–Fe)II(pz)[NiII(CN)4] and cellulose aerogels by in-situ growth and doping method (named CoFe@CA-IS and CoFe@CA-D, respectively). The hybrid aerogels possessed excellent iodine adsorption performance. The addition of (Co–Fe)II(pz)[NiII(CN)4] increased the porosity of the hybrid aerogels. The porosities of CoFe@CA-IS and CoFe@CA-D were reached 86.7% and 87.8%, respectively, which are higher than pure cellulose aerogels. Furthermore, the doping method provide a significant improve of adsorption performance. The equilibrium adsorption capacity of CoFe@CA-D reached 457.99 mg g−1 and the equilibrium adsorption capacity of CoFe@CA-IS was 194.34 mg g−1. In addition, the hybrid aerogels showed excellent recycle ability, the equilibrium adsorption capacity of CoFe@CA-IS and CoFe@CA-D remained 81% and 91% after 5 cycles. The results suggested that this metal-organic framework@cellulose hybrid aerogel showed great potential in iodine treatment and could be applied in a wide field.

Waste Cotton Fabric/Zinc Borate Composite Aerogel with Excellent Flame Retardancy

A waste cotton fabric (WCF)/zinc borate (ZB) composite aerogel with flame resistance was successfully synthesized through zinc borate immobilized in the cellulose aerogel by in situ formation by dissolving a waste cotton fabric in NaOH/urea aqueous solution. Morphology and composition were studied by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The thermal stability and flame retardancy with thermogravimetric analysis and ignition tests as well as microscale combustion calorimetry were tested. The results show that zinc borate is dispersed evenly in the pore and on the surface of the aerogel and has no significant effect on the porous structure of the WCF/ZB composite aerogel. In addition, the introduction of zinc borate can significantly improve the mechanical properties of composite aerogels. The compressive strength of pure WCF aerogels and WCF/ZB-9 aerogels increases from 0.028 to 0.70 MPa. The composite aerogel exhibits excellent thermal stability, flame retardancy, and self-extinguishing properties, which can effectively suppress heat release, and the heat release rate reduces from 190.70 to 5.45 W/g for the pure WCF aerogel and WCF/ZB-9 aerogel. Heat release capacity and total heat release of the pure WCF aerogel and WCF/ZB-9 aerogel decrease from 12.1 to 1.6 kJ/g and from 213 to 7 J·g–1 k–1, respectively. The WCF/ZB aerogel from the waste cotton fabric can be potentially applied to lightweight flame retardant fields.

Cellulose nanofibril (CNF) based aerogels prepared by a facile process and the investigation of thermal insulation performance

Herein, a facile method on fabricating aerogels with hierarchical porous structures was created by freeze-drying the cellulose nanofibril (CNF)/methyltrimethoxysilan (MTMS)/fumed silica (FS) suspension. FS was introduced for its porous structure, which could improve the thermal insulation performance of freeze-dried aerogels. The as-prepared aerogels were hydrophobic with improved mechanical properties (elastic recovery rate was up to 99.7%) and reduced thermal conductivity (0.027 Wm−1 K−1 at 25 °C). Most importantly, the addition of FS was proved to improve the thermal insulation stability of cellulose aerogels efficiently in different values of relative humidity (RH) and temperatures. The thermal conductivity of pure CNF aerogel conditioned at 25 °C and 95% RH was 196% higher than that of the fully-dried one, while the increase was 56% for the composite aerogel. Besides, at 30% RH, the thermal conductivity increased by 24% for the pure CNF aerogel when tested from 20 to 60 °C while only a 2% increase for the composite aerogel. Moreover, when tert-butanol was used as the solvent to optimize the distribution of the pores of freeze-dried aerogels, their thermal insulation performance was further improved. Our work provides easily available CNF/MTMS/FS ternary aerogels, which are stable in thermal conductivity in the changing environment.

Three-Dimensional Graphene Hybrid SiO2 Hierarchical Dual-Network Aerogel with Low Thermal Conductivity and High Elasticity

We describe lightweight three-dimensional (3D) graphene hybrid SiO2 aerogels (GSAs) with hierarchically robust interconnected networks fabricated via an in situ deposition procedure after a hydrothermal assembling strategy with graphene oxide sheets. The nano-/micron-thick SiO2 coating conformably grew over porous graphene templates with two constituents (e.g., graphene and SiO2) and formed chemically bonded interfaces. In addition, it significantly refined the primary graphene pores by hundreds of microns into smaller porous patterns. Studies of its mechanical properties verified that the graphene interframework made the ceramic composites elastic, while SiO2 deposition enhanced the strength required it to resist deformation. The higher SiO2 contents resulted in lower elasticity but larger strength because of the apparent nanosize effect of SiO2 ceramic thickness; GSAs with a density of 82.3–250.3 mg/cm3 (corresponding to SiO2 sol with concentration ranging from 5 to 20 wt %) could reach a good balance of strength and elasticity. Benefiting from hierarchical micronetworks consisting of semiclosed or closed pores, GSAs offer excellent thermal-insulation performance, with thermal conductivity as low as 0.026 W/(m·K). GSAs offer improved fire-resistant capacity rather than that of pure carbon-based aerogels via the synergic protection of SiO2 ceramic accretion. This highlights the promising applications of GSAs as lightweight thermal-shielding candidates for industrial equipment, civil architectures, and defense transportation vehicles.

Cellulose‐Conducting Polymer Aerogels for Efficient Solar Steam Generation

AbstractSeawater desalination and wastewater purification technologies are the main strategies against the global fresh water shortage. Among these technologies, solar‐driven evaporation is effective in extracting fresh water by efficiently exploiting solar energy. However, building a sustainable and low‐cost solar steam generator with high conversion efficiency is still a challenge. Here, pure organic aerogels comprising a cellulose scaffold decorated with an organic conducting polymer absorbing in the infrared are employed to establish a high performance solar steam generator. The low density of the aerogel ensures minimal material requirements, while simultaneously satisfying efficient water transport. To localize the absorbed solar energy and make the system floatable, a porous floating and thermal‐insulating foam is placed between the water and the aerogel. Thanks to the high absorbance of the aerogel and the thermal‐localization performance of the foam, the system exhibits a high water evaporation rate of 1.61 kg m−2 h−1 at 1 kW m−2 under 1 sun irradiation, which is higher than most reported solar steam generation devices.

Molybdenum trioxide impregnated carbon aerogel for gaseous elemental mercury removal

A novel gaseous elemental mercury (Hg0) removal agent was successfully synthesized via impregnation method, by using molybdenum trioxide (MoO3) as the active component and carbon aerogel (CA) as the carrier. The as-prepared samples maintained a large specific surface area and excellent pore structure of the pure carbon aerogel, so that MoO3 was better dispersed to obtain enhanced Hg0 removal performance. The maximum efficiency of elemental mercury removal was about 74%, achieved by Mo/C500 sample at 300 °C, while it still had good ability (nearly 60%) in the range of 500–700 °C. The mechanism of mercury oxidation removal was also verified by DFT calculation. This work should help in developing suitable materials for thermocatalytic oxidation of elemental mercury, and also provide some theoretical basis and data support for full-scale application of heavy metal mercury pollution control in coalfired power plants.

PLA coating improves the performance of renewable adsorbent pads based on cellulosic aerogels from aquatic waste biomass

Lightweight, hydrophobic, adsorbent pads based on aerogels from different cellulosic and nanocellulosic fractions extracted from Posidonia oceanica waste biomass were developed by a simple freeze-drying and PLA dipping method. The pure (nano)cellulosic aerogels presented highly porous structures, capable of adsorbing large amounts of oil (up to ~34 g oil/g aerogel); however, they lost their integrity when soaked in water. The incorporation of PLA hydrophobized the aerogels and improved significantly their mechanical performance (up to 10-fold increase in the compression stress). The most porous aerogel structures, obtained with the lowest (nano)cellulosic concentrations and with the less purified fractions, incorporated greater amounts of PLA upon dipping, which was mostly distributed filling in the pores. All the PLA-coated (nano)cellulosic aerogels presented a hydrophobic behaviour, with contact angles of 95–130° and selectively adsorbing greater amounts of oil (5.9–9.2 g oil/g aerogel) than water (2.8–6.7 g H2O/g aerogel). These materials present a great potential as adsorbent pads for oil spill cleaning and food packaging applications.

Preparation of phase change microcapsules-aerogels composites and the enhanced thermal properties

The performance of thermal insulation and solar-thermal conversion systems in modern building could be greatly improved by incorporation of phase change microcapsules (PCMs) into aerogels. In this study, a low-cost and high-performance phase change composited aerogels (PCCA) were successfully constructed by sol-gel method combined with ambient pressure drying procedure. The scanning electron microscope (SEM), transmission electron microscope (TEM) and N2 adsorption-desorption results showed that well-developed porous structure was retained when 40 wt% PCMs was added. Differential scanning calorimetry (DSC) revealed that the melting enthalpy and phase transition temperatures of PCCA were about 25.0 ℃ and 52.78 J/g, which was close to theoretical value. The infrared thermal images confirmed that PCCA had better thermal insulation and temperature control abilities than pure aerogels, thus the improved thermal performance make it a potential candidate to effectively use of solar energy in building application.

Fabrication of Cellulose Nanocrystal-g-Poly(Acrylic Acid-Co-Acrylamide) Aerogels for Efficient Pb(II) Removal.

In this work, cellulose nanocrystals (CNCs) obtained by the acid hydrolysis of waste bamboo powder were used to synthesize cellulose nanocrystal-g-poly(acrylic acid-co-acrylamide) (CNC-g-P(AA/AM)) aerogels via graft copolymerization followed by freeze-drying. The structure and morphology of the resulting aerogels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the CNC-g-P(AA/AM) aerogels exhibited excellent absorbent properties and adsorption capacities. Subsequent Pb(II) adsorption studies showed that the kinetic data followed the pseudo-second-order equation, while the adsorption isotherms were best described using the Langmuir model. The maximum Pb(II) adsorption capacity calculated by the Langmuir model reached up to 366.3 mg/g, which is a capacity that outperformed that of the pure CNC aerogel. The CNC-g-P (AA/AM) aerogels become structurally stable through chemical cross-linking, which enabled them to be easily regenerated in HCl solution and retain the adsorption capacity after repeated use. The aerogels were found to maintain 81.3% removal efficiency after five consecutive adsorption–desorption cycles. Therefore, this study demonstrated an effective method for the fabrication of an aerogel adsorbent with an excellent reusability in the effective removal of Pb(II) from aqueous solutions.

Silver nanoparticles cross-linked polyimide aerogels with improved high temperature microstructure stabilities and high mechanical performances

Nanoparticles can be considered as effective cross-linkers for PI aerogels. In order to investigate the effect of different nanoparticle-cross-linkers on the performances of aerogels, two types of silver nanoparticles, AgNPs (Ag nanoparticles) and AgNShs (Ag nanosheets) were modified via PATP (p-aminothiophenol) as cross-linkers and then added into PAA (polyamic acid) solution derived from BPDA (3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride) and ODA (4, 4′-diaminodiphenyl ether) to form wet gel. The wet gel was processed with supercritical CO 2 drying to fabricate cross-linked polyimide aerogels. Raman, XPS and TG-IR were carried out to prove successful modification of silver nanoparticles. The as-prepared aerogels had densities around 0.2 g cm −3 . Nitrogen adsorption desorption tests and mechanical tests were conducted to characterize the performance of aerogels at room temperature and high temperature (above 150 °C). The results showed that comparing to pure PI aerogels, aerogels cross-linked with silver nanoparticles had higher compressive strength and Young's modulus, which comes to 3.4 MPa and 52.7 MPa, respectively. Besides, silver nanoparticles cross-linked aerogels also had better high temperature stability in both size and microstructure comparing to pure PI aerogels. With remarkable mechanical properties and high temperature microstructure stabilities, these aerogels show potential in many areas of application. • Two kinds of silver nanoparticles are aminated and served as cross-linkers of PI aerogels. • Aerogels added with 5 wt % cross-linker have the highest mechanical properties among aerogels with similar densities. • Silver nanoparticles cross-linked aerogels have better high temperature microstructure stability than pure PI aerogels.

Nanofibers reinforced silica aerogel composites having flexibility and ultra‐low thermal conductivity

AbstractFor the sake of enhancing the performance of flexible silica aerogel in practical applications, flexible SiO2/SnO2 nanofibers (SSNF) reinforced flexible silica aerogel composites (abbreviated as SiO2‐SSNF) were successfully prepared. Firstly, the SiO2/SnO2 nanofibers with fine diameter (~320 nm) and excellent flexibility were prepared by electrospinning technology. Then the aerogel composites were synthesized by adding the flexible SSNF to the silica solution and through the sol‐gel method and ethanol supercritical drying technology. The effects of different content of the nanofibers on thermal conductivity and Yong's modulus of SiO2‐SSNF aerogel composites were investigated. The SiO2/SnO2 nanofibers were randomly dispersed in the flexible silica aerogel and the great integrity of the material result in smaller linear shrinkage, better thermal protection, and mechanical properties compared with those pure SiO2 aerogels. The final SiO2‐SSNF aerogel composites possess excellent thermal conductivity (0.025‐0.029 W/(m∙K)) and higher Yong's modulus (70 kPa), which was twice than that of the pure silica aerogel. This prepared SiO2‐SSNF aerogel composites can be better used in thermal insulation due to its excellent flexible and thermal insulation property.

Preparation and oil–water separation of 3D kapok fiber‐reduced graphene oxide aerogel

AbstractBACKGROUNDOil spills from oil tankers and ships or industrial accidents have serious impacts on the ecological environment. There is an urgent need for finding effective ways to resolve these problems. The use of low‐cost and efficient adsorbents is considered to be one of the most effective ways.RESULTSIn this study, an ultra‐light 3D kapok fiber‐reduced graphene oxide (TKF‐rGO) aerogel was prepared by a simple and green one‐step hydrothermal method. The kapok fiber used as skeleton was embedded in a graphene network to successfully form a 3D aerogel structure. The as‐prepared TKF‐rGO aerogel featured low density, excellent mechanical strength, high thermal stability, and high hydrophobic lipophilicity. Furthermore, continuous oil–water separation could be achieved by the aerogel when connected to a vacuum system. The adsorption capacity of TKF‐rGO aerogel for various common oil products and organic solvents was 1.5‐fold greater than that of pure rGO aerogel and six‐fold greater than that of polypropylene melt spray, respectively. In addition, the initial adsorption capacity of the as‐prepared TKF‐rGO aerogel was maintained at 94% after eight cycles.CONCLUSIONThe TKF‐rGO aerogel could be synthesized by a low‐cost and green method, which was suitable for commercial production, and showed competitive adsorption capacities for oil removal. Thus, the TKF‐rGO aerogel is expected to be employed as a promising adsorbent in the removal of oil spill or hazardous organic solvents from water. © 2019 Society of Chemical Industry

Zeolitic imidazolate framework-8/polyvinyl alcohol hybrid aerogels with excellent flame retardancy

Zeolitic imidazolate framework-8 (ZIF-8) was synthesized and used as a flame retardant in polyvinyl alcohol (PVA) aerogels. The introduction of ZIF-8 increased the roughness of the cell walls due to attachment of the ZIF-8 particles. The ZIF-8 also promoted the thermal degradation of PVA, but increased the residue yield. The limiting oxygen index (LOI) increased from 19.5% for pure PVA aerogel to 24.0% for the ZIF-8/PVA hybrid aerogel. The self-extinguishing behavior of the ZIF-8/PVA hybrid aerogel was observed in the UL-94 vertical burning test, while the PVA aerogel burned out finally. The peak heat release rate (PHRR) and total heat release (THR) of the ZIF-8/PVA hybrid aerogel were 44.2% and 12.8% lower than those of pure PVA aerogel, respectively. The decomposition of ZIF-8 to zinc oxide enhanced the barrier effect of the residues, which accounted for the suppressed PHRR and THR. This study demonstrated that incorporation of ZIF-8 can result in tunable flame retardancy for fire safety application.

Preparation of FeBTC/silica aerogels by a co-sol-gel process for organic pollutant adsorption

In this paper, a series of FeBTC/silica hybrid aerogels (FeBTC-SA) have been successfully prepared by a facile method. Specifically, Fe (III) metal salts were added to a silica (SiO2) sol containing trimesic acid (H3BTC) at room temperature for co-sol gelation and then CO2 supercritical drying was introduced to obtain FeBTC/SiO2 hybrid aerogels. The composites have been completely characterized by FT-IR, SEM, elemental analysis and HR-TEM analysis techniques. Meanwhile, adsorption properties of hybrid aerogels have also been systematically investigated through a typical organic dye methyl blue (MB). The results show that all the as-synthesized FeBTC-SA composites have a three-dimensional porous network structure. The TEM analysis further shows that the composite is a semi-crystal, while the FeBTC particles are crystalline of MIL-100(Fe). Furthermore, with the increase of FeBTC content, MB adsorption performance of composites is increasingly improved. By the elaborately manipulating the π–π interactions between MB and the benzene rings of FeBTC/SiO2 hybrid aerogels, the static adsorption efficiency of FeBTC-SA (3:50) (molar ratio of Fe:Si = 3:50) can be quickly reached at 99.1%, which is increased by 11% compared to the pure SiO2 aerogels. Therefore, It provides a new avenue for the important applications of hybrid aerogels as highly efficient adsorbents in water purification.