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Conductive carbon materials from biomass have recently attract scholars’ interest, but their preparation usually requires both high carbonization temperature and multiple carbonization process. To solve the above problems, bamboo industrial powder (BP) waste was used as raw materials and mixed directly with FeCl3 as the catalyst, followed by conducting pyrolysis and one-step carbonization to prepare conductive carbon powder. Influence of the mass ratio of BP to FeCl3, carbonization temperature and carbonization time on the conductivity of BC was surveyed. According to comprehensive performance of the resulting bamboo charcoal (BC), the best conditions were identified as carbonization at 1300 °C for 2 h with the mass ratio of BP to FeCl3 for 50:1. Under the conditions, the graphite structure transformed from amorphous structure was confirmed by XRD and Raman. And the well-defined lattice fringes were observed and presented as the curve structure with the spacing of 0.340 nm, which was the sign of the graphitic structure. Under optimal conditions, the conductivity value reached 38.08 S·cm−1. This work provides a theoretical basis for the formation of highly graphitized BC from bamboo in one-step method and the highly value-added conductive BC has a potential application in electromagnetic shielding and electrochemistry.

Lignin is an ideal substance for preparation of functional materials. Specifically, lignin nanospheres (LNPs) are formed by self-assembly of lignin molecules and show great application prospects in drug delivery, electrochemistry, catalysis

Background: Primary membranous nephropathy (PMN) refers to an immune complex-mediated cause of the nephrotic syndrome, which is one of the leading causes of end-stage renal disease worldwide and imposes a heavy burden on patients with PMN and the medical insurance system. The risk of complications and unsatisfied efficacy limit the use of traditional diagnostic methods in some patients. Thus discovery of novel diagnostic biomarkers is needed. The aim of the present study was to identify potential diagnostic biomarkers for PMN and revealing the significance of immune cell infiltration for its pathogenesis. Methods: Three gene expression profiles (GSE108109, GSE104948, GSE47185) from samples from patients with PMN and controls were obtained from Gene Expression Omnibus (GEO) database as a training set, and GSE99340 was downloaded as a validation set. Differentially expressed genes (DEGs) were identified using the training set, and functional correlation analyses were conducted by R software. Three machine-learning strategies were performed to identify potential diagnostic biomarkers for PMN and receiver operating characteristic (ROC) curves was used for both training sets and the validation set to evaluate the diagnostic efficacy of these biomarkers. In addition, cell-type identification by estimating relative subsets of RNA transcript (CIBERSORT) bioinformatics algorithm was employed to assess the immune cell infiltration in PMN and the relationships between the diagnostic biomarkers and infiltrating immune cells were characterized. Results: Eighty-six DEGs received the recognition. CCAAT/enhancer-binding protein delta (CEBPD) and Myozenin 2 (MYOZ2) were identified as biomarker genes for the diagnosis of PMN. As indicated from the immune cell infiltration analysis, neutrophils, memory B cells and monocytes may be involved in the development of PMN. Additionally, both CEBPD and MYOZ2 might correlate with immune cells in diverse degrees. Conclusions: CEBPD and MYOZ2 are potential diagnostic biomarkers of PMN, and the immune cell infiltration plays important roles in the pathogenesis of this disease.

A superhydrophobic stainless steel mesh (called “mesh” in short) is an ideal device to solve oil pollution accidents by oil–water separation. However, its widespread application is prevented by complicated preparation, weak durability, and particularly poor mechanical strength. It is well known that the used adhesives play a key role in the mechanical strength of superhydrophobic coatings. In this study, polyvinylidene fluoride (PVDF) and polydimethylsiloxanes (PDMSs) were respectively used as adhesives and lignin-nanocellulose crystal (L-CNC) particles as main structure materials to prepare L-CNC coated superhydrophobic meshes. Moreover, the meshes coated with L-CNC/PVDF and L-CNC/PDMS were compared with respect to the properties of wettability, sandpaper abrasion, oil–water separation, etc. The results showed that the L-CNC/PVDF-coated mesh had a higher water contact angle (WCA = 154.2°) than the L-CNC/PDMS-coated one (WCA = 152.6°), but worse abrasion resistance. Both of them showed high-efficiency oil/water separation with collection rates above 94.5% and stable reusable ability as the oil collection rates for toluene was still above 93.8% after reusing thirty times, meanwhile showing good heat, UV, acid and alkaline resistance properties.

Cotton fabric, as an important material, is suffering from some defects such as flammability, easy pollution and so on, therefore, it is important to make a flame-retardant and superhydrophobic modification on cotton fabric. In this study, we demonstrated a preparation of high-efficiency flame-retardant and superhydrophobic cotton fabric with double coated construction by a simple multi-step dipping. First, the fabric was immersed in branched poly(ethylenimine) (BPEI) and ammonium polyphosphate (APP) water dispersions successively, and then immersed in polydimethylsiloxane (PDMS)/cellulose nanocrystals (CNC)-SiO2 toluene dispersion to form a BPEI/APP/PDMS/CNC-SiO2 (BAPC) composite coating on the surface of the cotton fabric. Here, the hydrophobic modified CNC-SiO2 rods were used to construct the superhydrophobic layer and the BPEI/APP mixture was used as the flame-retardant layer, as well as SiO2 particles which could further improve the flame-retardant effect. PDMS was mainly used as an adhesive between the BPEI/APP layer and the CNC-SiO2 layer. The resulting cotton fabric shows outstanding flame-retardant properties, in that the value of oxygen index meter (LOI) reaches 69.8, as well as excellent superhydrophobicity, in that the water contact angle (WCA) is up to 156.6°. Meanwhile, there is a good abrasion resistance, the superhydrophobicity is not lost until the 16th abrasion cycles and the flame retardant retains well, even after 100 abrasion cycles in an automatic vertical flammability cabinet under a pressure of 8.8 kPa.

The objective of this research was to investigate the presence of residual lignin in cellulose fibers on the efficiency and energy consumption during nanofibers processing. Four kinds of lignin-containing cellulose nanofibers (LCNFs) from switchgrass, yellow poplar, hybrid poplar, and pine, respectively, were isolated via organosolv fractionation coupling mechanical grinding. Nanofibrils were observed after organosolv fractionation. The details of their morphological features, chemical structures, water retention value (WRV), and thermal degradation characteristics were revealed and compared. Mean diameters of nanofibers separated from switchgrass, yellow poplar, hybrid poplar, and pine were 27.9 nm, 25.4 nm, 24.6 nm, and 21.5 nm, respectively. The presence of lignin for the four types of LCNFs led to a decrease in energy consumption and an increase in WRV, among which pine nanofibers show the best with an average energy consumption of 0.511 kWh/kg and a WRV of 537%. It was also demonstrated that increasing lignin content for LCNFs could contribute to the sample’s thermal stability. In conclusion, exact benefits of residual lignin for nanofiber will facilitate its preparation process and extend its application.

It is still a challenge to prepare air filtration materials with high filtration efficiency and good thermal stability from renewable materials. In this study, cellulose nanofibril (CNF), poly (vinyl alcohol) (PVA), and bamboo activated charcoal (BAC) were used to build an air filtration system with double filtration by mixing and freeze-drying. The resulting CNF/PVA/BAC aerogel sheet reached a filtration efficiency of 99.69% for PM2.5 due to its double filtration from the network structure of CNF and electrostatic adsorption of BAC. The composite material also showed high thermal stability with its filtration efficiency over 95% even after exposure to 200 °C. After modification, the hydrophobic CNF/PVA/BAC filtration sheet could be reused for over 5 times by water washing whereby the filtration efficiency remained above 95%. The environmentally friendliness excellent filtration efficiency and simplistic fabrication make the aerogel sheet a potential material choice to cope with the severe air pollution today.

Plastics and foaming agents are often used to prepare large-size and low-density bamboo charcoal (BC) based composites. In this study, a plastic-free and foaming agent-free BC based composite was prepared by substituting sodium silicate (SS) for plastics. The effect of both the BC particle sizes and the usage amount of SS on the mechanical and adsorptive properties of the BC/SS composites were investigated. The experimental results show that when the BC particle size is 270 μm and the mass ratio of BC to SS is equal to 10:5, the BC/SS composite has the optimal foaming effect and best comprehensive properties. In addition, the foaming pores of the composite are caused by water vapor, which has difficulty escaping the BC because of the blockage of SS during the hot pressing process. In the BC/SS composite (10:5), the static bending intensity and the compressive strength reach respectively 6.13 MPa and 5.5 MPa, and the average pore size and porosity are 557.85 nm and 52.03%, respectively. In addition, its formaldehyde adsorptionrate reaches 21.6%. In view of good mechanical properties, formaldehyde adsorption, and environmentally friendly performance, the BC/SS composite has a great potential as a core layer of interior building materials.

Complex preparation methods and weak mechanical properties of superhydrophobic coatings hinder their applicability. To address these problems, cellulose nanofibers (CNFs) were used as structural materials to augment the roughness properties, while polydimethylsiloxane (PDMS) was used as the adhesive. Based on the results of previous studies, superhydrophobic coatings with good mechanical properties can be prepared by spraying the mixture onto a substrate surface, herein, the mixture comprised modified CNFs and PDMS. The resulting coating possessed excellent superhydrophobicity, which allowed a maximum water contact angle (WCA) of 158&deg, Furthermore, it exhibited great knife-scratch-resistance properties and good abrasion performance, which was evaluated by abrading with 800-grit sandpaper for 19 cycles (abrasion length of 380 cm) under a 100 g load. Based on the simple operation and abrasion resistance, the coating shows great potential for practical application.

Lignin-containing cellulose nanofibers (L-CNFs) with various lignin contents were produced by a grinding process from switchgrass, which were pretreated using organosolv fractionation. The effect of different fractionation conditions (temperature and time) and different number of grinder passes on the energy consumption and morphologies of L-CNFs were investigated. Results showed that nanosized fibers were found in organosolv-fractionated samples before grinding. After several grinding passes, L-CNFs with a similar degree of fibrillation as commercial cellulose nanofibers (CNF) were obtained from the fractionated materials. It is beneficial to save energy consumption in the grinding process. The dimensions and dispersion of L-CNFs were significantly influenced by the lignin content in the L-CNFs. Longer and well-separated nanofibrils were observed from transmission electron microscopy and fluorescence microscopy with appropriate residual lignin (~ 13.7 ± 1.59%) in the L-CNFs compared to those of L-CNFs with either lower or higher lignin contents. Therefore, microsized and nanosized lignin particles were successfully obtained in a single process, and they not only facilitated L-CNFs dispersion but also help to decrease the energy consumption during the grinding process.

A large number of superhydrophobic coatings are prepared using individual particles (especially SiO2) to build rough surfaces. However, those surface structures collapse very easily, resulting in poor mechanical strength of the coating. To overcome this problem, cellulose nanocrystals (CNCs) are used as a framework material to prepare a necklace-like CNC/SiO2 nanostructure (referred to as CNC/SiO2 rod) via in-situ growth of SiO2 as building blocks of superhydrophobic coatings. The CNC/SiO2 superhydrophobic coatings could be prepared by spraying or smearing the CNC/SiO2 rods onto substrates treated with a commercial spray adhesive. The reason for selecting CNC is its high strength and appropriate size, which results in the formation of a firm grass-like surface microstructure when it is partially installed within the adhesive. The resulting coatings have ultra-high mechanical robustness under very harsh conditions and can resist abrasion by 240 grit sandpaper for 50 cycles (1000 cm) under a load of 100 g. They also perform well under finger-wipe, knife-scratch, water-drip, ultraviolet radiation, and acidic and alkaline conditions as well as have self-cleaning and oil-water separation ability. Given the simplicity of the proposed method and the excellent performance, these coatings should find wide use in a range of applications.

In this study, we reported PVA nanocomposite films enhanced by polyethyleneimine (PEI)-lignin contained cellulose nanofibers (LCNFs) via the solvent casting method. An easy and available method was preformed to prepare LCNFs using a supermasscolloider from unbleached bamboo waste after a mild alkaline pretreatment. The results demonstrate that LCNF–PEI can greatly improve mechanical, hydrophobic, anti-UV shielding and antibacterial properties of the composite films. The tensile strength of LPP1 film was improved to 54.56 MPa, which was higher than 39.37 MPa of PVA film. The water contact angle of films increased from 35° to 104° with an increase in LCNF content from 0 to 6 wt%. Meanwhile, the nanocomposite film demonstrated the effect of full shielding against ultraviolet light when the amount of LCNF–PEI reached 6 wt%. The addition of LCNF–PEI endowed excellent antibacterial activity (against S. aureus and E. coli), which indicated potential applications in the packaging field.

To improve on the poor strength and flame retardancy of a chitosan (CS)-based functional film, cellulose nanofiber (CNF) was taken as the reinforced material and both ammonium polyphosphate (APP) and branched polyethyleneimine (BPEI) as the flame-retardant additives in the CS matrix to prepare the CS/CNF/APP/BPEI composite film by simple drying. The resulting composite film showed good mechanical strength, with a tensile strength reaching 71.84 Mpa due to the high flexibility of CNF and the combination of CS, CNF and BPEI through strong hydrogen bonding interactions. The flame retardant-performance of the composite film greatly enhanced the limit oxygen index (LOI), up to 32.7% from 27.6% for the pure film, and the PHRR intensity decreased to 28.87 W/g from 39.38% in the micro-scale combustion calorimetry (MCC) test due to the ability of BPEI to stimulate the decomposition of APP, releasing non-flammable gases such as CO2, N2, NH3, etc., and forming a protective phosphating layer to block the entry of O2. Based on the good flame retardancy, mechanical strength and transparency, the CS/CNF/APP/BPEI composite film has a great potential for future applications.

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&ndash, 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.

Cellulose-based film material, due to its remarkable physicochemical properties, environmentally friend and low cost, has been widely applied in many high-end areas. However, the lack of functional properties (e.g., flame resistance) except poor mechanical performance severely hinders their further applications. Herein, bamboo-based phosphorylated cellulose nanofibrils (B-PCNFs) were prepared through a simple two-step method composed of phosphorylation and mechanical grinding process. The resultant film prepared via solvent casting process shows an excellent mechanical strength of 115.9 MPa, remarkable elongation at break of 53.1%, high Young's modulus of 2.5 GPa and impressive work of fracture up to 41.8 MJ m−3, respectively, which should be contributed to the formation of dense and homogeneous polymer networks reinforced by enhanced multiple interactions. When burned against the flame of alcohol lamp (700–800 °C), BHL-PCNF film also delivers appealing structural stability even over 25s, demonstrating a prominent flame resistance. Meanwhile, compared to original one, the peak heat release rate (PHRR) and total heat released (THR) of BHL-PCNF film produce a dramatical reduction, i.e., 87.3% and 86.6% for PHRR and THR, respectively. Based on the evolution of morphological and chemical structure, the highly improved flame resistance is strongly contributed to the synergy of phosphorus containing group and lignin, resulting in a protective layer composed of PxOy compound and carbon layer. The proposed mechanism for the enhanced flame retardant property is also declared and clarified. Thereby, this phosphorylated cellulose-based film that integrates outstanding mechanical performance and excellent intrinsically flame resistance holds promising potential candidate in practical applications, such as flame-retardant packaging materials.

Due to its excellent adsorption and humidity control function, bamboo charcoal (BC) has often been mixed with polypropylene (PP) to produce PP/BC composites for interior paneling applications. However, due to the poor foaming quality of PP, PP/BC composites suffer as a result of their high density, which limits their scope of use. Here, to improve its foaming quality, PP was modified with ethylene vinyl acetate (EVA), and then the EVA-modified PP (E-PP) was mixed with different contents of BC (0 wt.%–50 wt.%), as well as foaming agent (Azodicarbonamide, AC) and its auxiliaries (ZnO, Znst), in a twin-screw extruder, followed by hot-pressing at high temperature to obtain foamed E-PP/BC composites. The resulting composites showed good porosity and pore distribution with an increase of BC content by up to 20%. Further increase in the BC content seemed to cause the foaming performance to decrease significantly. The product density and adsorption rate increased, while the mechanical strength decreased with increasing BC content. At a BC content of 40 wt.%, the foamed E-PP/BC composite showed the best combined performance, with a density of 0.90 g/cm3, 24-h formaldehyde adsorption rate of 0.48, and bending strength of 11.59 MPa.

Organic solvents, which are often used in the preparation process of superhydrophobic coatings, are volatile and toxic. The inorganic particles also widely used in their preparation are difficult to degrade, which may result in environmental contamination. In this study, commercial lignin-coated cellulose nanocrystal (L-CNC) particles, which are environmentally friendly and biodegradable and formed by CNC solution containing a small amount of lignin in a spray-drying process, uniting strength with a rough surface, were used to provide a good foundation for a superhydrophobic coating due to the different size and irregular surfaces of the particles. A superhydrophobic coating is successfully prepared by spraying a L-CNC/polyvinyl alcohol (PVA) composite paint and then modifying it via chemical vapor deposition (CVD). The resulting coating has not only good superhydrophobicity and self-cleaning properties, but also excellent abrasion resistance. In addition, no organic solvents or inorganic particles were used in the preparation process. Thus, this coating could potentially be used in some applications that require nontoxicity or environmental safety such as food packaging.

A paper-based wearable supercapacitor with excellent foldability and tailorability is fabricated from a chopped carbon fiber (CCF)-reinforced cellulose paper electrode material by coating with reduced graphene oxide (RGO) and polypyrrole (PPy) via in situ polymerization. The CCFs not only form an interpenetrating conducting network that acts as highly conductive electron transfer highways for the RGO/PPy layer in the paper electrode, but also endow the resulting electrode with an excellent areal capacitance of 363 mF cm−2 and a volumetric energy density of 0.28 mW h cm−3. Further, the CCFs give the electrode remarkable mechanical robustness, guaranteeing foldability and tailorability, with only slight loss of capacitance after repeated folding 600 times. Even after being subjected to severe cut-in fracture, the capacitance retention is up to 84%, indicating outstanding damage tolerance. The present study reveals a promising candidate for flexible wearable energy storage devices that are required to function in harsh environments.

A large number of superhydrophobic coatings are prepared using individual particles (especially SiO

Nanofibrillated cellulose (NFC) is a renewable and environmentally friendly material. Its large ratio of length to diameter and its pliability are very helpful for forming a three-dimensional network structure that could contribute to suitable roughness for superhydrophobic coatings. At present, superhydrophobic coatings have limited applications, mainly due to their poor abrasion resistance and durability. Therefore, in this study, a semi-translucent NFC superhydrophobic coating was prepared by spraying NFC ethanol suspension onto a wood surface that had been previously covered with a commercial spray paint as adhesive, followed by modification via phase chemical vapor deposition (CVD) to reduce surface free energy. The results showed that in addition to good superhydrophobic and self-cleaning properties, the coating also possessed excellent abrasion resistance and durability and was able to resist sandpaper abrasion, knife-scratch, finger-wipe, long-time impregnation in water, UV radiation, and low temperatures, demonstrating good potential for development and application.

Cellulose nanofibrils (CNF) were used to reinforce silica aerogels, aiming to ameliorate the aerogels' inherent brittleness. The CNF-reinforced silica aerogels were prepared through the elaboration of silica particles interpenetrated with a nanocellulosic network structure by immersion of the CNF aerogels into a silica solution in a two-step sol–gel process (first, hydrolysis of tetraethyl orthosilicate (TEOS) and second, condensation under alkaline conditions). The relationships among the silica content, the density, and the compressive properties of the composite aerogels were investigated. A response surface methodology (RSM) was applied to optimize the preparation process (CNF concentration, TEOS concentration, pH value of condensation process and immersion time) with the target being to synthesize a desired aerogel with improved mechanical properties. The results show that density can be seen as a function of the silica content, and that the two had a positive dependent relationship. The compressive properties were also greatly affected by the silica loading into the cellulosic scaffold. The composite aerogel displayed high compressive properties at 40–50 wt% silica particles. The optimal condition would be a CNF aerogel of 5% solid content immersed into a 2.5 mol L−1 TEOS sol with condensation at pH value of 10 for 10 min. The compressive modulus (6.57 MPa) and compressive strength (1.37 MPa) of the composite aerogel greatly exceeded those of the pure silica aerogel, without substantial increases in density (0.1 g cm−3). The composite aerogel also had good insulation properties (thermal conductivity was 0.0226 W m−1 K−1) and hydrophobicity (contact angle 152.1°) and thus can be considered as a multi-functional aerogel capable of applications in a wide variety of areas.

To develop a smart multifunctional wood material, thermochromic energy-storage microcapsules were incorporated into coatings while painting medium density fiberboard (MDF). The morphologies, chemical structures, and thermal properties of the microcapsules were characterized. The coating performance, including the thickness, wearability, and adhesion were investigated. The thermochromic and energy-storage properties of the coated MDF were evaluated using chroma meter and differential scanning calorimeter, respectively. Four different microcapsule concentrations were determined to analyze the effect of the concentration on performance of the multifunctional material. The microcapsules demonstrated a sensitive color change phenomenon and possessed a latent heat of over 90 J/g. The color of the surface of the coated MDF could repeatedly change between blue and light brown within a temperature range of 20–39 °C, presenting a “color hysteresis” phenomenon over a heating (decolorization) and cooling (coloration) cycle. Meanwhile, the coated MDF could be considered an energy-storage material with a phase-change temperature range of 12–38 °C. The multifunctional MDF could be suitable for use as a decorative and thermo-regulating material. The concentration of the microcapsules obviously reduced the wearability of the coatings, but had no significant effect on their adhesion. The total color contrast of the MDF increased from 31.26 to 57.03 as the microcapsule concentration increased from 2.5 to 10 % (of the coating weight), while a linear positive correlation was verified between the enthalpy of the coating and the concentration. The microcapsule concentration could potentially be used to adjust the performance of the multifunctional MDF.

An interesting wood-based all-solid-state supercapacitor is produced using reduced graphene oxide (RGO) coated on wood transverse section slice (WTSS) as electrode material by means of a low-cost, eco-friendly, and simple method for the first time. The RGO-coated WTSS electrode has a porous 3D honeycomb framework due to the hierarchical cellular structure of the WTSS substrate and can function as an electrolyte reservoir. This special construction endows this novel electrode with good areal capacitance (102 mF cm−2) and excellent cyclic stability (capacitance retention of 98.9% after 5000 cycles). In addition, the supercapacitors exhibit good mechanical flexibility and preserve almost constant capacitive behavior under different bending conditions. Our study introduces a new and eco-friendly material design for electrodes in future flexible energy storage devices that closely resemble natural materials. Open image in new window

We utilized a simple dipping-and-polymerization method to prepare an interesting electrode material consisting of polypyrrole (PPy) polymerized on a wood transverse section slice (WTSS), and fabricated a wood-based supercapacitor. The novel electrode has a 3D honeycomb porous framework, a high capacitance (0.61 F cm−2) and excellent flexibility. These make the PPy-coated WTSS electrode an excellent alternative candidate for flexible energy storage.

It is a challenge for a superhydrophobic coating to overcome the poor robustness and the rough surface structure that is usually built using inorganic particles that are difficult to degrade. In this study, a robust superhydrophobic coating is facilely prepared by using commercial biodegradable lignin-coated cellulose nanocrystal (L-CNC) particles after hydrophobic modification to build rough surface structures, and by choosing two different adhesives (double-sided tape and quick-setting epoxy) to support adhesion between the L-CNC particles and the substrates. In addition to excellent self-cleaning and water repellence properties, the resulting coatings show outstanding mechanical strength and durability against sandpaper abrasion, finger-wipe, knife-scratch, water jet, UV radiation, high temperature, and acidic and alkali solutions, possessing a wide application prospect.

Monolithic cellulose nanofibrils (CNF)-silica composite aerogels were successfully prepared by immersing CNF aerogels into a silica solution in a two-step sol-gel process (initial hydrolysis of tetraethyl orthosilicate (TEOS) followed by condensation of silica particles). Aerogels were characterized by SEM, BET surface area test, bulk density and silica content analysis, FTIR spectroscopy, and compression test. The form of SiO2 existing in the composite aerogel was the spherical individual particles coated on CNF fibrils. The pH value of condensation solution was found to have great influence on the properties of the composite aerogels. By varying the pH value of condensation atmosphere from 8 to 12, the bulk densities of composite aerogels were able to be linearly increased from 0.059gcm(-3) to 0.29gcm(-3)，and the silica content in the matrix sharply jumped from 3wt% to 79wt%. The porosities of the aerogels remained very high, between 85 and 96%, and the surface area of the composite aerogel reached up to 700.1m(2)g(-1). The compression properties of the composite aerogel improved greatly compared with those of the silica aerogel, about 8-30 times higher. Moreover, the compressive strength of the composite aerogel prepared in this work greatly exceeded the conventional insulation materials found in the recent commercial market, and without substantial increases in thermal conductivity. Hence, the findings of this research offer a promising application for composite aerogels and give a theoretical basis for developing new advanced materials.