Wet Gel Research Articles

The coagulant dipping process of nitrile latex: investigations of former motion effects and coagulant loss into the dipping compound.

Coagulant dipping, the process used in thin glove manufacture, involves electrolyte ions diffusing from the surface of a hand-shaped former into latex compound, causing a deposit (wet gel) to accumulate on the former. In this work, two aspects of the process were examined, both experimentally and theoretically. For the experimental work, a commercial nitrile latex was used. The motion of formers through a latex dipping tank is intuitively expected to affect the electrolyte diffusion and hence the wet gel growth. This was investigated at laboratory scale with small glass formers moving in a metre-long dip tank. Former velocities ranged from zero to almost 0.2 m s-1. No effect of former lateral movement on wet gel thickness was observed. One obvious explanation is that most of the coagulant diffusion occurs within the wet gel deposit, which provides protection to the diffusive flux. However, the critical zone is just ahead of the coagulating front, where coagulant is present in the liquid compound at concentrations below the level needed for coagulation. A fluid mechanical model was constructed that assumed a uniform fluid flow along the side face of a rectangular former. The model confirmed that for calcium nitrate, the most commonly used coagulant, the effect of movement is very small. In the second investigation, coagulant leakage into the host latex compound during the dwell time was investigated by taking samples during repeat static dips. This experiment was modelled using diffusion theory, focusing on the critical zone just outside the wet gel at the point of former withdrawal. The model and experiment agreed well, both showing a small but definite coagulant leakage that tended towards a plateau concentration. Coagulant leakage from a moving former was also considered, from a theoretical perspective. In this case, the mechanism is advective movement of coagulant from the critical zone into the host compound. In the worst case, where all of this coagulant is swept away, the model suggested that the plateau coagulant concentration could reach an amount that would cause coagulation. Reduced flow in the critical zone (boundary layer) and former shape are factors that would reduce leakage.

Opportunities and Methods for Using Fluorescent Gel as a Proxy for Pathogen Transfer in Biosecurity Research

Highlights While fluorescing gel may evaporate from a surface, luminance of the surface does not change. Fluorescing gel exhibits thresholds beyond which additional gel density does not increase luminance. Fluorescing gel only transfers between surfaces when it is wet. There are limits to relating luminance and mass transfer. Fluorescent material is a useful proxy for contamination transfer demonstration and research. Abstract. Glo Germ fluorescing material is a popular tool for teaching and researching contaminant transfer in and out of agriculture. The objectives of this paper were to: (1) quantify relationships between gel area density (mass per unit area) on a surface and its luminance, and (2) identify factors important in measuring Glo Germ gel transfer from one surface to another. Varying densities of Glo Germ gel were applied to paper, plastic, and rubber surfaces; each combination was replicated three times. Digital images collected over one hour were analyzed for luminance (the average gray value per unit area) under ultraviolet light. Changes in mass were also measured. For the gel transfer objective, a fixed weight was placed over varying wet and dried fluorescent material densities on paper and plastic surfaces. Gel masses were weighed, and images of the surface and receptor were taken before and after transfer. Evaporation was significantly faster (p = 0.0019) on the paper surface compared to the plastic surface. The luminance did not change as the gel evaporated from either surface. For each material, luminance initially increased with increasing density until a threshold, after which additional fluorescing gel density did not change luminance. The thresholds for paper, plastic, and rubber surfaces were 0.018, 0.014, and 0.041 g cm-2, respectively. Wet gel transfer test results suggest that transfer is easier to quantify on the receptor than the source. The dried gel did not exhibit measurable transfer. This research found limitations in equating mass transfer and luminance, but luminance threshold values can inform maximum Glo Germ application for imaging purposes. These research results support continued research and outreach with fluorescent material to reduce and prevent the spread of disease or other harmful contaminants in food and animal production. Keywords: Biosecurity, Fluorescence, Luminance, Mass transfer.

Preparation of aerogel-like SiOC ceramic with honeycomb structure and its high-temperature performance

Development of lightweight ceramic aerogel with enhanced thermal insulation and high temperature resistance is required in the field of thermal insulation. Here, a aerogel-like SiOC ceramic with honeycomb structure was prepared by solvothermal method using polyhydromethylsiloxane (PHMS) as precursor and divinylbenzene (DVB) as cross-linker followed by freeze-drying and pyrolysis. The pore size and homogeneity of the honeycomb structure could be further controlled by the content of DVB through adjusting the crosslinking degree of the PSO wet gel. The aerogel-like SiOC possessing uniform honeycomb structure with the pore size of 20–50 µm and the wall thickness of 3–6 µm is obtained at the mass ratio of DVB:PHMS of 2:1. The aerogel-like SiOC exhibits low density (0.14 g·cm−3) and low thermal conductivity (0.0577 W·m−1·K−1). Moreover, it maintains the honeycomb structure after high temperature treatment at 1400 °C in argon and 800 °C in air indicating its good thermal stability. This work provides a novel route for the preparation of the aerogel-like SiOC ceramic with honeycomb structure and designable overall performance, further expanding its application in thermal insulation.

High Amylose Corn Starch Gels—Investigation of the Supermolecular Structure

AbstractAqueous gels based on two high amylose corn starch (HACS) genotypes with different amylose (AM) contents (HYLON V [HACS‐50] and HYLON VII [HACS‐70]) are prepared by gradation of the polymer concentration (6 and 9% w/w) and storage duration (1 and 14 days). The supermolecular structure of the wet gels is investigated by means of confocal laser scanning microscopy (CLSM), and the dried starch gel material examines crystallographically using X‐ray diffraction (XRD) and morphologically using scanning electron microscopy (SEM). In particular CLSM reveals that the gel structure shows changes with the storage time. XRD experiments reveal the existence of the B‐type crystalline structure as well as a remarkable portion of the V‐type, and higher crystallinity (Xc) is found after long‐term storage. Observation of the dried gel material's surface facilitates the assumption of a fractal‐based arrangement (structure of retrograded starch) within the starch gel network. The results are discussed closely with obtained data related to the molecular level of the gel matrix involved starch polymers, which are reported in previous publications.

Effect of Cross-Linking Cations on In Vitro Biocompatibility of Apple Pectin Gel Beads.

The study aimed to compare the in vitro biocompatibility of pectin gels formed by different cross-linking cations. Hydrogel beads named CaPG, ZnPG, FePG, and AlPG were prepared from 4% solutions of apple pectin using ionotropic gelling with CaCl2, ZnCl2, FeCl3, and AlCl3, respectively. Cations influenced the gel strength of the wet gel beads in the following order (least strong) Ca2+ < Zn2+ < Fe3+~Al3+ (most strong). The swelling degree of the CaPG beads after 24 h of incubation in the RPMI-1640 medium was 104%, whereas the ZnPG, FePG, and AlPG beads swelled by 76, 108, and 134%, respectively. The strength of the pectin gel decreased significantly after incubation in the RPMI-1640 medium for 24 h, regardless of the cross-linking cation, although the FePG beads remained the strongest. All the pectin beads adsorbed serum proteins to a low degree, however the serum protein adsorption by the ZnPG and FePG beads (1.46 ± 0.87 and 1.35 ± 0.19 µg/mm2) was more than the CaPG and AlPG beads (0.31 ± 0.36 and 0.44 ± 0.25 µg/mm2). All the pectin beads reduced the production of TNF-α and IL-10 by hPBMCs in response to LPS stimulation. The IL-1β response of cells to LPS was significantly reduced by the CaPG, ZnPG, and FePG beads, whereas the AlPG beads enhanced it twofold. The CaPG, FePG, and AlPG beads had no cytotoxicity. The viability of hPBMCs and human fibroblasts incubated with ZnPG beads was 5.3 and 7.2%, respectively. Thus, the use of different cross-linking cations changed the properties of the pectin gel, which is important for biocompatibility.

Polyvinylidene Fluoride Aerogels with Tailorable Crystalline Phase Composition.

In this work, polyvinylidene fluoride (PVDF) aerogels with a tailorable phase composition were prepared by following the crystallization-induced gelation principle. A series of PVDF wet gels (5 to 12 wt.%) were prepared from either PVDF-DMF solutions or a mixture of DMF and ethanol as non-solvent. The effects of the non-solvent concentration on the crystalline composition of the PVDF aerogels were thoroughly investigated. It was found that the nucleating role of ethanol can be adjusted to produce low-density PVDF aerogels, whereas the changes in composition by the addition of small amounts of water to the solution promote the stabilization of the valuable β and γ phases. These phases of the aerogels were monitored by FTIR and Raman spectroscopies. Furthermore, the crystallization process was followed by in-time and in situ ATR-FTIR spectroscopy. The obtained aerogels displayed specific surface areas &gt; 150 m2 g-1, with variable particle morphologies that are dependent on the non-solvent composition, as observed by using SEM and Synchrotron Radiation Computed micro-Tomography (SR-μCT).

The osmocapillary effect on a rough gel surface

A gel surface is generally biphasic at equilibrium. Asperities can be submerged under solvent due to osmocapillary phase separation and be flattened due to elastocapillary deformation. The surface behavior of a gel is governed by the interaction between osmocapillary phase separation and elastocapillary deformation. We develop a linear osmocapillary model that numerically predicts the phase separation and deformation on a gel surface. We use the model to simulate the deformation of a sinusoidal surface and a computer-generated self-affine rough surface. The simulation shows that the behavior of a gel surface is governed by the osmocapillary length and elastocapillary length relative to the characteristic length of the surface roughness. As the relative magnitude of these length scales change, the surface can behave like a rigid material with little deformation, a liquid with a completely flattened surface, a dry elastomer where deformation is not accompanied by osmocapillary phase separation, or a wet gel where a large portion of the surface is covered by the solvent. Contrary to the existing understandings, we show that a gel surface can be mostly covered by the liquid solvent, although the gel is solid, and the resulting surface energy can be significantly lower than the prediction from existing models neglecting osmocapillary phase separation.

Comparison of Heat-Treated and Unheated Vermicompost on Biological Properties of Calcareous Soil and Aloe Vera Growth under Greenhouse Conditions in a Mediterranean Climate

Determining how intermittently applied heat treatment during the preparation of vermicompost changes the effectiveness of the fertilizer is a challenge. In this study, organic Aloe vera was grown using heat-treated cattle manure vermicompost (IVC) and unheated cattle manure vermicompost (VC). Additionally, these two vermicomposts were combined with vermiwash (LV) and applied to the soil. Thus, the cumulative effect of vermicompost on soil biological properties (number of bacteria, dehydrogenase, urease, alkaline phosphatase, β-glycosidase) and plant growth (plant height, number of leaves, leaf biomass yield, number of suckers, fresh gel weight) was investigated. According to the results obtained, it was understood that HVC-30+LV, HVC-60+LV, and VC-60+LV applications were more effective on soil biological properties. On the other hand, HVC-30+LV and HVC-60+LV applications were found to be effective on plant growth. In addition, increases of 140% in soil bacterial number, 170% in dehydrogenase activity, 125% in urease activity, 122% in alkaline phosphatase activity, 123% in β-glycosidase activity, 65% in plant height, and 45% in leaf biomass yield and wet gel weight were observed. Accordingly, it can be stated that heat-treated cattle manure vermicompost applied to the soil at a rate of 30 t ha−1 together with vermiwash is beneficial for improving the biological properties of calcareous soil and for organic Aloe vera cultivation.

Preparation of Organic/Inorganic Composite Aerogel through Gelation and Supercritical Fluid Drying of Para-Aramid Fibril/Silicon Alkoxide Dispersion

Organic/inorganic composite aerogels were obtained from poly-paraphenylene terephthalamide (PPTA) micro-fibrils and methyltrimethoxysilane (MTMS). They are prepared using the following four-step process: the gelation of 1.0 wt% PPTA fibril dispersion containing MTMS by cooling, dehydration condensation of MTMS by immersing the wet gel in a catalyst solution, substituting the solvent in the wet gel, and supercritical drying of the wet gel. When the PPTA/MTMS dispersion containing 1.0 wt% MTMS was gelatinized, the PPTA fibrils strongly adhered to each other, and the PPTA/MTMS composite wet gel obtained better morphological stability. Furthermore, the wet gel prevented shrinkage during the catalyst soaking and supercritical fluid drying processes, and the resulting aerogel had a minimum density of < 0.03 g/cm3. It also had a composite network structure with silica spheres of approximately 30 nm attached to the PPTA fibril network. In contrast, when the PPTA/MTMS dispersions containing 5.0 or 10 wt% MTMS were gelatinized, the obtained composite aerogels had an entangled structure of PPTA fibril networks around silica spheres ranging from 500 nm to 700 nm in size. Moreover, aerogels comprising PPTA/MTMS dispersion with 10 wt% MTMS had a specific surface area of 610 m2/g and retained 70 % of their weight after the heat resistance evaluation at 600°C.

(Digital Presentation) A Low-Modulus, Soft and Stretchable Wearable Electrocardiography Sensor-System Patch

Electrocardiography (ECG) is a primary tool for diagnosis of various types of disease and disorders such as arrhythmias, coronary heart disease, heart attack, mental disorders, etc. Reliable wearable ECG devices can be a valuable tool in early diagnosis and effective treatment of such disease and disorders. Convention wearable ECG sensor-systems are rigid, bulky, expensive, and the recorded ECG signals using these wearable devices lack required accuracy for medical diagnosis mainly due to motion artifacts that is originated from slippage of sensors on skin and/or instable interface between the soft sensor and the rigid electronic circuits.Here, we report a low-modulus, soft and stretchable wearable electrocardiography (ECG) sensor-system patch which enables continuous and long-term recording of ECG signals with minimal motion artifacts. This system consists of two reusable, detachable-attachable patches: sensor patch and circuit patch, as shown in Figure 1a. The reusable multi-wall carbon nanotube (MWCNT) based sensor patch is fabricated on stretchable elastomer substrate by our developed cost and time-effective method. Reusable, front-end and wireless circuit patch is made by integration of the off-the-shelf integrated circuit components with three-dimensional (3D) stretchable-deformable interconnects (SDI). SDIs are 3D springs of liquid metal (EGaIn). Unlike other reported liquid metal based interconnects, SDI has been designed in 3D form to increase the stretchability and make it low-modulus and robust to deformations in all directions. The stretchability of SDI structure is beyond 500% (the limit of our measurement system) without any negligible change in electrical resistivity of the interconnects. With less than 1% change in the resistance of SDIs after 50,000 cycles of applied tensile strain of 200%, the SDI structure ensures reliable stretchability and durability of the circuit patch for long-term electrocardiography.The sensor patch is soft, stretchable and it is fabricated using a low-cost scalable method. This soft and stretchable ECG sensor-system shows comparable performance with respect to medical grade Ag/AgCl wet gel electrodes. Our CNT-PDMS sensors shows low electrode-skin interface impedance and low susceptibility to motion artifact which similar of it in medical grade Ag/AgCl wet gel sensors (Fig. 1b). Further, it is waterproof, reusable and comfortable to wear.The circuit patch includes a rechargeable battery and ECG signals is wirelessly sent to a personal device such as cellphone, tablet and laptop through Bluetooth low energy (BLE) and it is displayed in real-time (Fig. 1c) Our developed sensor-system is a multi-use platform which can be applied for the detection of EMG, EEG or EOG signals. Figure 1

Re-fluidising the aged gel for high-density alumina green body

A green body with a density as high as possible is critical to diminish the crisis of deformation or cracking when large-size parts are sintered. Here, a new method, i.e., re-fluidising the aged ceramic gel is developed to prepare the high-density green body. Alumina slurry with 56 vol% solid loading and copolymers of isobutylene and maleic anhydride were aged without vaporisation and re-fluidised by non-intrusive shearing after removing the exuded water. The re-fluidised slurry was re-casted. The resultant wet gel was dried and deboned at a low temperature. The relative density of the obtained green body was 64.6%, 1.5% higher than that without aging and re-fluidising. The linear sintering shrinkage of the body decreased by 0.7%. The enhanced green density is explained from the viewpoint of the solid loading and the structure of the slurry.

Fabrication of boehmite nanofiber aerogels by a phosphate gelation process for optical applications

A transparent wet gel was obtained in a few minutes at room temperature by adding an aqueous phosphoric acid solution of appropriate concentration to boehmite nanofiber sol. After room temperature aging and supercritical carbon dioxide drying, low bulk density aerogels with visible light transmittance of over 90% at 10 mm thickness were obtained. These aerogels exhibited high Young’s modulus and visible light transmittance, while having the same bulk density as the samples obtained by a conventional gelation process using a base. The high optical transmittance of the aerogel were hardly lost even at high humidity because the phosphorylation of the skeletal surface reduced the percentage of hydroxyl groups. The three-dimensional imaging inspection of the exterior and interior of the aerogel was carried out. The various developments reported in this paper make aerogels with ultralow bulk density (<0.01 g cm−3) and high visible light transmission even more promising for applications in the physical field. Graphical abstract

Organic-Inorganic Double-Gel System Thermally Insulating and Hydrophobic Polyimide Aerogel.

Aerogel materials are used in various fields, but there is a shortage of aerogel materials with an excellent combination of mechanical properties, thermal stability, and easy preparation. In this study, polyimide aerogel materials with superior mechanical properties, thermal stability, and low thermal conductivity were prepared by forming a double-gel system in the liquid phase. The amino-modified gel, prepared by coating SiO2 nano-microspheres with GO through a modified sol-gel method (SiO2@GO-NH2), was subsequently homogeneously dispersed with PAA wet gel in water to form a double-gel system. The construction of a double-gel system enabled the PI aerogel to shape a unique honeycomb porous structure and a multi-layered interface of PI/SiO2/GO. The final obtained PI aerogel possessed effective thermal conductivity (0.0309 W/m·K) and a high specific modulus (46.19 m2/s2). In addition, the high thermal stability (543.80 °C in Ar atmosphere) and the ability to retain properties under heat treatment proved its durability in high thermal environments. The hydrophobicity (131.55°) proves its resistance to water from the environment. The excellent performance of this PI aerogel and its durability in thermal working environments make it possible to be applied in varied industrial and research fields, such as construction and energy, where heat and thermal insulation are required.

Design, Fabrication and Performance Assessment of Flexible, Microneedle-Based Electrodes For ECG Signal Monitoring.

Microneedle-based electrodes have attracted significant attention for the monitoring of physiological signals, including ECG, EMG, and E OG, as they have the potential to eliminate the skin preparation and stability issues associated with conventional wet gel electrodes. This paper describes the development of a polymeric flexible microneedle electrode (FMNE) that does not require skin abrasion and can be used for long-term ECG monitoring. Fabricated using a combination of epoxy resin microneedles bonded to a flexible substrate, the performance of the FMNE was compared to that of a conventional wet-gel electrode by simultaneously capturing the ECG signal using both electrodes, and estimating the signal-to-noise ratio (SNR) of each. Results show that the flexible electrode can acquire ECG signals in which all the characteristic components of the wave are visible, and that are comparable in quality to those obtained using commercial wet electrodes. Bland-Altman plots were drawn to validate the performance of FMNE, and show that the mean difference ± standard deviation in SNR obtained using wet electrodes and FMNE was [Formula: see text]. Clinical Relevance- These microneedle-based 'dry electrodes' could be used in long-term monitoring of biopotential activity.

Optically Unobtrusive Zeolite-Based Dry Electrodes for Wearable ECG Monitoring

Novel dry electrodes are increasingly evolving for monitoring electrocardiograms compared to the widely used <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ag/AgCl</i> (wet) electrodes as there is no skin preparation or wet gel needed. Many fabricated dry electrodes are however opaque, and the problem of skin irritation and rashes continue to pose a concern. In this paper, an optically unobtrusive dry electrode based on the iono-electric properties of zeolite is developed and proposed for continuous electrocardiogram (ECG) monitoring. An easily moldable composite of the sodium form of nano-porous zeolite and polydimethylsiloxane (PDMS) is reported for the first time. The electrical and bio-electrical characterizations are evaluated for 24 pairs of electrodes which were fabricated with two filler materials (Zeolite 4A and 13X), two filler concentrations (4 wt% and 12 wt%), three diameters (30 mm, 20 mm, and 10 mm), and differing thicknesses. High input impedance and high conductivity of the electrodes have proven the suitability for biosignal acquisition. ECG signals are acquired using each pair of electrodes. Results related to impedance, conductivity, and SNR measurements over a frequency range up to 10 kHz are presented. Among the 24 pairs, the results indicate that signal-to-noise ratio (SNR) for Zeolite 13X/PDMS- based filler with a concentration of 4 wt% and diameter of 30 mm has the highest SNR of 42.9 dB and conductivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.58 \mu \text{S}$ </tex-math></inline-formula> /mm. These electrodes are optically unobtrusive and easy to fabricate. Hence this process yields promising results for the next generation of wearable cardiovascular heart monitoring systems.

Cover Feature: Formation of Iron (III) Trimesate Xerogel by Ultrasonic Irradiation (Eur. J. Inorg. Chem. 15/2022)

The Cover Feature shows the ultrasound-assisted formation of Fe-BTC gels, iron carboxylate metal-organic frameworks (MOFs) constructed from iron ions and 1,3,5 benzenetricarboxylic acid linkers. The gels were obtained by two different procedures: ultrasonic irradiation (US) of different water solutions containing the linker and iron nitrate, with or without the additive tetramethylammonium hydroxide. Gelation was observed regardless of the duration of the irradiation, the precursor concentration, the additive, or the US apparatus used. While drying, the wet gels underwent shrinking and cracked into tiny fractions of transparent solid xerogels consisting of interconnected spherical, thermally stable nanoparticles with a permanent microporous structure. The authors acknowledge Prof. Christoph Hartl for gently assisting with the cover′s graphic layout. More information can be found in the Research Article by G. Mannias, M. Pilloni and co-workers.

Colloidal CdS Quantum Dot Fibers Prepared by Electrospinning of Their Wet Gel for Quantum Nanowires

Colloidal CdS Quantum Dot Fibers Prepared by Electrospinning of Their Wet Gel for Quantum Nanowires

A novel preparation of solid amine sorbents for enhancing CO2 adsorption capacity using alumina-extracted waste

A “wet gel impregnation” method (WGI) was applied to prepare modified CO2 sorbents derived from alumina-extracted residue of coal ash (AR). Tetraethylene pentamine (TEPA) was selected as an amine polymer and it was evenly dispersed on the surface of AR. And the effects of loading amount, impregnation method, and adsorption temperature on CO2 adsorption capacity of the sorbent were investigated by thermogravimetric analyzer (TGA). The results showed that the desired sorbent with 60% TEPA loading via WGI had the maximum CO2 adsorption capacity of 3.45 mmol/g under 100% CO2 at 75 °C. This was attributed to the fact that the loading in wet gel state dramatically improved TEPA dispersion on the supports and increased the saturated loading of amine. Moreover, the sorbent still maintained stable CO2 uptake after five repeated adsorption-desorption cycles. These results suggested that amine-impregnated AR sorbent synthesized by WGI was an excellent and low-cost sorbent for CO2 capture.

Three‐Level Hierarchical 3D Network Formation and Structure Elucidation of Wet Hydrogel of Tunable‐High‐Strength Nanocomposites

AbstractThe structural characterization of wet gel state hydrogels at multi‐length scales ranging from nanometers to micrometers is very challenging and rarely reported. Herein, tunable high‐strength nanocomposite hydrogels based on cellulose nanofibers with various cross linkers are synthesized and characterized. Synchrotron tomography and small‐angle X‐ray scattering methods are combined to quantitatively elucidate 3D hierarchically wet gel state network structures, providing an understanding on the structure–properties relationship of hydrogels. The hierarchical 3D network of wet gel demonstrates three levels of structures: 1) the bundle aggregated by cellulose nanofibers; 2) physically crosslinked bundle networks; and 3) fractal‐structure agglomerates composed of aggregated network domains. The finding of fractal agglomerate structures tuned by crosslinker characteristics provides fundamental knowledge to explain a variation of several orders of magnitude of mechanical properties and reveals different formation mechanisms, opening a new and flexible prospect for wet gel state material design and processing control.

Ambient-Dried Silica Aerogel Powders Derived from Coal Gangue by Using One-Pot Method.

In this paper, we report a new and convenient method for the synthesis of insulating aerogel by recycling solid waste coal gangue, which can reduce the industrial production cost of silica aerogels and realize high value-added utilization of solid waste. Sodium silicate was prepared from a cheap industrial waste coal gangue as the precursor for silica aerogels, which was used for silica wet gel preparation by a one pot method; this method of solvent exchange/surface modification was carried out quickly by mechanical stirring process, and the wet gels derived from coal gangue were dried under ambient pressure condition. A high surface area (~748 m2/g) nanostructured aerogel with a 3D open porous microstructure was synthesized, which exhibits a low density (~0.18 g/cm3) and a superior thermal insulation performance (~0.033 W·m−1·K−1). More significantly, the synthetic yield of silica aerogel powder by recycling coal gangue can reach 92%.