Bacterial Cellulose Aerogels Research Articles

Electrocatalytic and Conductive Vanadium Oxide on Carbonized Bacterial Cellulose Aerogel for the Sulfur Cathode in Li-S Batteries

Many transition-metal-oxide-based catalysts have been investigated to chemically bind soluble lithium polysulfides and accelerate their redox kinetics in lithium-sulfur (Li-S) battery chemistry. However, the intrinsic poor electrical conductivities of these oxides restrict their catalytic performance, consequently limiting the sulfur utilization and the rate performance of Li-S batteries. Herein, we report a freestanding electrocatalytic sulfur host consisting of hydrogen-treated VO2 nanoparticles (H-VO2) anchored on nitrogen-doped carbonized bacterial cellulose aerogels (N-CBC). The hydrogen treatment enables the formation and stabilization of the rutile VO2(R) phase with metallic conductivity at room temperature, significantly enhancing its catalytic capability compared to the as-synthesized insulative VO2(M) phase. Several measurements characterize the electrocatalytic performance of this unique H-VO2@N-CBC structure. In particular, the two kinetic barriers between S8, polysulfides, and Li2S are largely reduced by 28.2 and 43.3 kJ/mol, respectively. Accordingly, the Li-S battery performance, in terms of sulfur utilization and charge/discharge rate, is greatly improved. This work suggests an effective strategy to develop conductive catalysts based on a typical transition metal oxide (VO2) for Li-S batteries.

Preparation of Cu-modified bacterial cellulose aerogels derived from nata de coco towards the enhanced adsorption of hydrophobic organic solvents

Preparation of Cu-modified bacterial cellulose aerogels derived from nata de coco towards the enhanced adsorption of hydrophobic organic solvents

Self-assembled bacterial cellulose imprinted aerogel for efficient and selective adsorption of erbium from tailings wastewater

Selective recovery of high value rare earth elements from tailings wastewater is an economical and environmental measure. In this study, we constructed highly elastic embossed bacterial cellulose aerogel (BCP-I) for highly selective adsorption of erbium ions using bio-based material (2,2,6,6-tetramethyl-1-piperidinyloxy-mediated bacterial cellulose) as a substrate material in concert with chitosan (CS) and polyethyleneimine (PEI). CS and PEI contain abundant functional monomers, which can cooperate with bacterial cellulose and Er(III) to construct more imprinting sites, which not only improves adsorption performance of BCP-I, but also makes aerogel more stable. In order to analyze physical and chemical properties of aerogels, it was characterized by scanning electron microscope, Fourier transform infrared spectrometer and thermogravimetric analysis. Adsorption experiments showed that BCP-I had a good adsorption effect on Er(III), and the maximum adsorption capacity could reach 95.99 mg g−1. After five adsorption cycles, cycling experiments showed that adsorption performance of BCP-I was still in good condition. In conclusion, BCP-I is a good choice for the recovery of Er(III) because of its environmental friendliness, high selectivity and good reproducibility.

Hydrogel electrolyte based on sodium polyacrylate/KOH hydrogel reinforced with bacterial cellulose aerogel for flexible supercapacitors

Hydrogels are particularly promising electrolyte materials for constructing flexible and safe quasi-solid state supercapacitor due to their good flexibility, ionic conductivity and intrinsic safety. However, it remains a challenge to simultaneously obtain excellent mechanical robustness, high ionic conductivity and outstanding flexibility, particularly in sub-zero temperatures. Hence, we introduced a novel bacterial cellulose (BC) aerogel reinforced sodium polyacrylate/potassium hydroxide (PANa/KOH) hydrogel as a hydrogel electrolyte for flexible alkaline supercapacitor. The PANa/BC/KOH hydrogel electrolyte showed outstanding mechanical property (stress of 1.1 MPa), excellent anti-swelling performance and high ionic conductivity of 1.91 S m−1 at 25 °C, 1.35 S m−1 at −25 °C, exhibiting a superior anti-freezing performance. Benefiting from these intriguing integrated characteristics, the asymmetric supercapacitor (SC-PANa/BC/KOH) assembled PANa/BC/KOH hydrogel electrolyte and CoNi LDH@CC//AC@CC electrodes delivered a superior energy density of 25.63 W h kg−1 at a power density of 1200 W kg−1 and maintained a good retention of 92.05 % after 10,000 cycles. Meanwhile, the SC-PANa/BC/KOH exhibited excellent flexibility and safety, which is well adapted to various extreme conditions, such as weight-loading, bending and hammering. This work provided new sights into design of strong, anti-freezing, anti-swelling and high ionic conductive hydrogel electrolyte, paving the way for developing extremely safe wearable storage devices.

Preparation of ε-polylysine and hyaluronic acid self-assembled microspheres loaded bacterial cellulose aerogels with excellent antibacterial activity

ε-Polylysine (ε-PL) is a broad antibacterial polymer. In this work, ε-PL and hyaluronic acid (HA) were self-assembled into microspheres and loaded into regenerated bacterial cellulose (RBC) to prepare RBC/HA/ε-PL aerogels. The RBC/HA/ε-PL aerogel showed a three- dimensional network structure with high porosity. The antibacterial activity of the prepared RBC/HA/ε-PL aerogel against E. coli, C. albicans and S. aureus was carried out by bacterial growth evaluation, bacteria fluorescent stain, bacterial morphology observation and the leaked protein determination. The results showed that RBC/HA/ε-PL aerogel exhibited excellent antibacterial performance by destroying the cell membranes. This work provides a novel and green material prepared by natural polymers, with potential applications in antibacterial materials area.

Biomass-derived nanocellulose aerogel enable highly efficient immobilization of laccase for the degradation of organic pollutants

Laccase is a promising biocatalyst for pollutant degradation and water purification. However, laccase can only improve the stability of enzyme activity and achieve its significant catalytic effect after effective immobilization. Herein, we report a general strategy to integrate nanocellulose aerogel and laccase for high-efficiency degradation of organic pollutants. Biomass-derived functional bacterial cellulose (BC) aerogel with a nanonetwork structure and high porosity was prepared by biosynthesis, solvent replacement, and atom transfer radical polymerization (ATRP) procedures. Subsequently, a biocatalyst platform was fabricated by “coupling” ATRP-modified BC aerogel with abundant active sites with laccase through ion coordination. The results demonstrated the biocatalyst platform not only has good biological affinity, but also has high enzyme load and structural stability. Meanwhile, the degradation rates of reactive red X-3B and 2, 4-dichlorophenol reached 94.5% and 85.2% within 4 h, respectively. The strategy disclosed herein could provide a practical method for the degradation of organic pollutants.

Recyclable Bacterial Cellulose Aerogel for Oil and Water Separation

Bacterial cellulose (BC) aerogel has great potential in treating oil spill and organic pollutant. However, its inherent hydrophilicity and poor rigidity limit its practical application and recyclability. In this study, elastically compressible and high oil-absorbing aerogels were developed by freeze-drying aqueous suspensions with appropriate BC concentrations, followed by a chemical vapor deposition of methyltrimethoxysilane with ammonia as catalyst. The modified aerogel shows high water contact angle of 142° and enhanced compression resistance. The effect of BC concentration on the absorption capacity and recyclability of aerogel has been investigated. The results show that the aerogel prepared with 0.3 wt% BC exhibits simultaneously high absorption capacity (121.8–284.1 g/g) and excellent recyclability. Futhermore, the aerogel could also separate chloroform-water mixture by gravity-driven filtration, giving the separation efficiency of 96.7%. Therefore, this economical green aerogel provides a feasible strategy for solving oil leakage in industry.

Nanoporous Magnetic Carbon Nanofiber Aerogels with Embedded α-Fe/γ-Fe Core–Shell Nanoparticles for Oil Sorption and Recovery

Biomass-based carbon aerogels have received a lot of attention as oil sorbents or oil/water separators due to their effectiveness, low cost, and vast availability of natural resources as their precursors. Magnetically functionalizing the carbon aerogel improves its reusability by magnetic recovery after oil sorption. This work fabricated magnetic carbon nanofibers (MCF) aerogels from the pyrolysis of magnetic bacterial cellulose (MBC) aerogels. The effect of the pyrolysis temperature on the phase transformation and functionalities of the MCF aerogel was investigated. The combined characterization techniques concluded that the MBC aerogel consists of the BC nanofiber matrix decorated with nonmagnetic FeC4H2O4 and magnetic Fe3O4 nanoparticles, which transformed into amorphous carbon nanofibers anchored with the α-Fe/Fe3O4 core–shell structured nanoparticles after pyrolysis at 700 °C. Increasing the pyrolysis temperature to 800–900 °C led to the formation of purer amorphous carbon nanofibers, whereas the nanoparticles turned into the α-Fe/γ-Fe core–shell structure. At 1000 °C, the amorphous carbon structure is better developed and coated on the α-Fe/γ-Fe core–shell nanoparticles. The interpretation explains the results from the magnetic measurement very well and fits perfectly on the Fe–C phase diagram. Furthermore, the MCF aerogels show excellent properties as an efficient oil sorbent, such as large surface area, low density, and hydrophobic properties. Among the samples, the MCF aerogel pyrolyzed at 700 °C (MCF700) exhibits the most desirable properties while requiring the lowest pyrolysis temperature. It could adsorb various oils and organic solvents with high sorption capacity and could be recycled several times. With its magnetic attraction ability, the MCF700 could be magnetically manipulated toward oil, and it could be retrieved after use without direct human contact. These synergistic functionalities make it practically helpful for oil-spill remedies over a large-scale area.

A Strong, Anti-Freezing, Anti-Swelling and High Ionic Conductive Hydrogel Electrolyte Based on Bacterial Cellulose Aerogel Reinforced Pana/Koh Hydrogel for Flexible High Performance Supercapacitor

A Strong, Anti-Freezing, Anti-Swelling and High Ionic Conductive Hydrogel Electrolyte Based on Bacterial Cellulose Aerogel Reinforced Pana/Koh Hydrogel for Flexible High Performance Supercapacitor

Nanocellulose-based aerogels decorated with Ag, CuO and ZnO nanoparticles: Synthesis, characterization and the antibacterial activity

In this work, porous bacterial cellulose aerogels (BCA) were prepared by 1-step (BCA-1) and 3-step (BCA-3) exchange of solvent inside the bacterial cellulose hydrogel (0.65 %) with tertiary butyl alcohol followed by freeze-drying. BCA-3 was used as a template for Ag, CuO, and ZnO nanoparticles by reducing the corresponding salt using sodium borohydride (NaBH4) as a reducer agent. The silver nanoparticles (Ag NPs) were grown onto the BCA-3 scaffold (Ag/BCA-3) by adjusting the amount of AgNO3 with two different processes. Similarly, CuO and ZnO cellulosic nanocomposites (CuO/BCA-3 and ZnO/BCA-3) were fabricated by the optimized amount (0.1 M) and method (method-2). Aerogel and metal nanoparticle composites were characterized by Brunauer-Emmett-Teller (BET); UV–visible spectrophotometry (UV–Vis); X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR); Scanning electron microscopy (SEM); Energy dispersive spectroscopy (EDS); and Transmission electron microscopy (TEM) analysis. Results showed that the web-like entangled structures of aerogels have specific surface areas as high as 87–97 m2g−1. Ag/BCA-3 and CuO/BCA-3 exhibited a spherical morphology of NPs with an average particle size of about 50 nm and 10 nm, respectively. ZnO/BCA-3 resulted in hexagonal morphology with around 50 nm. The metal nanocomposites showed antibacterial activity against Klebsiella pneumonia (gram-negative) and Staphylococcus aureus (gram-positive) bacteria.

Enhanced hydrogen evolution under visible light by a ternary composite photocatalyst made of CdS and MoS2 modified with bacterial cellulose aerogel

Enhanced hydrogen evolution under visible light by a ternary composite photocatalyst made of CdS and MoS2 modified with bacterial cellulose aerogel

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb 2+ ion

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb ²⁺ ion

Electrically conductive biocompatible composite aerogel based on nanofibrillated template of bacterial cellulose/polyaniline/nano-clay

Bacterial cellulose (BC) aerogel owing to its porous and 3D structure, poses a suitable matrix for embedding nanomaterials and polymers. Herein, BC composites comprising nano-clay/polyaniline (PANI) were synthesized via a two-step procedure. Clay nanoplatelets were dispersed in the BC membrane to form a nanofibrillated template for aniline in-situ polymerization leading to formation of a double interconnected network of electrically conductive path within the aerogel. Deposition of PANI particles on BC/clay nanocomposite was confirmed by FTIR, XRD, FESEM, and EDX techniques. The surface electrical conductivity of 0.49 S/cm was obtained for the composite aerogel comprising 5 wt% nano-clay which is 16 folds higher than that of the sample without nano-clay. Thermal stability and storage modulus of the aerogels was improved by inclusion of PANI and nano-clay. Synergistic effect of clay and polyaniline on biocompatibility and cell adhesion was obtained with no mutagenic or carcinogenic effects. The developed electrically conductive composite aerogels can be utilized as suitable scaffolds for tissue engineering applications demanding a good balance of flexibility, dimensional and thermal stability and biocompatibility.

Production of Bacterial Cellulose Aerogels With Improved Physico-Mechanical Properties and Antibacterial Effect.

Aerogels have gained significant interest in recent decades because of their unique properties such as high porosity, low density, high surface area, and excellent heat and noise insulation. However, their high cost and low mechanical strength limit their practical application. We developed appropriate conditions to produce aerogels with controlled density, high mechanical strength, and thermal characteristics from bacterial cellulose (BC) synthesized by the strain Komagataeibacter sucrofermentans H-110. Aerogels produced using TEMPO oxidized BC (OBC) exhibited high mechanical strength and lower shrinkage than those from native bacterial cellulose (NBC). Compared to the NBC, the use of TEMPO-oxidized BC with oxidation degrees (OD) of 1.44 and 3.04% led to the reduction of shrinkage of the aerogels from 41.02 to 17.08%. The strength of the aerogel produced from the TEMPO-oxidized BC with an oxidation degree of 1.44% was twice that of the aerogel produced from NBC. The addition of Mg2+ at concentrations of 20 and 40 mM during the preparation of the aerogels increased the strength of the aerogels by 4.9 times. The combined use of TEMPO-oxidized BC and Mg2+ allowed pore size reduction from 1,375 to 197.4 μm on the outer part of the aerogels, thereby decreasing the thermal conductivity coefficient from 0.036 to 0.0176 W/(m•K). Furthermore, novel biocomposites prepared from the aerogels based on NBC and OBC and sodium fusidate, which have high antibiotic activity against Staphylococcus aureus, were obtained. Owing to their antibacterial properties, these aerogels can be used as functional biomaterials in a wide range of applications such as in tissue engineering and fabrication of wound dressing materials.

Novel synthesis of carbon nanofiber aerogels from coconut matrix for the electrochemical detection of glucose

Bacterial cellulose aerogels (BCAs) were obtained from a delicious food grade coconut. Following with a simple process of carbonized calcination (700 °C~1100 °C). The obtained coconut matrix carbon nanofiber aerogels (CMCNFs) exhibit low density (≤3.47 mg/cm3), high surface area (≥1102 m2/g), and high porosity (≈99.6%), which are much higher than those of common BCAs owing to the removal of hydrogen, oxygen and other elements along with only small volume changes. Due to the flexibility of the nanofiber matrix of our presoma, the three-dimensional network micro-structure is preserved during high temperature carbonization process. The obtained CMCNFs show an excellent conductivity bearing a direct electron transfer process between glucose oxidase (GOx) and electrode surface in the electrochemical processes. It was discovered that CMCNFs can achieve a fast direct electron transfer (DET) of GOx to the rapid detection of glucose. This character should be related to the three-dimensional pore structure determined by carbonization temperature, which has been proved that the CMCNFs calcined at 1000 °C possesses the best capabilities. With merits above, a highly sensitive glucose sensor is successfully prepared by the simple carbonization of coconut cellulose matrix, which expands the application scope of bacterial cellulose aerogels. This work also offers insights for the future develop of protein-based electrochemical devices.

Proton-conductive membranes with percolated transport paths for aqueous redox flow batteries

Tremendous efforts have been dedicated to developing sustainable and affordable ion exchange membranes for flow batteries. Challenges remain in terms of high cost, low coulombic efficiency caused by the crossover of active species, and stability. Inspired by the highly hydrophilic and interconnected 3D networks of nanofibers of bacterial cellulose (BC), an unprecedented ion exchange membrane possessing high ionic selectivity is created by impregnating a hydrophobic copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into BC aerogel scaffolds. The high proton conductivity of the membrane stems from the intrinsically high hydrophilic network of the BC fibrils, which offers a percolated pathway for the proton conduction. At the same time, the selectivity arises from the hydrophobic lamination on the BC scaffold that acts as a barrier for the migration of vanadium ions and reduces its crossover. Therefore, the hydrophilic ion transport paths of BC inside of a stable PVDF-HFP matrix result in a high proton conductivity of 0.0095 S cm−1 at 25 °C and a significantly less vanadium permeation rate. Besides, the membrane yields a high tensile strength of 114 MPa and excellent thermal stability. Moreover, vanadium redox flow battery assembled using the BC/PVDF-HFP membrane demonstrated cyclings for 300 continuous cycles at a constant current density of 100 mA cm−2 and achieved an average coulombic efficiency of 97.56%, voltage efficiency of 81.56%, and energy efficiency of 79.49%. The higher CE, and, therefore, energy efficiency of the BC/PVDF-HFP membrane than those of the Nafion 115 can be attributed to the natural percolated 3D networks of BC.

Bacterial cellulose aerogels: Influence of oxidation and silanization on mechanical and absorption properties

Biodegradable aerogels may help to develop eco-friendly technological pathways to increase the efficiency of chemical processes. In the present work, we describe the preparation of a novel bacterial cellulose aerogel oxidized by TEMPO, nanofibrillated in a blender, and silanized with methyltrimethoxysilane, resulting in four different types of aerogel. The aerogels produced from the double-functionalized cellulose suspension (BCOXNS) were compared to other non-oxidized (BCN and BCNS) and non-silanized (BCOXN) aerogels All aerogels were very light (density 10–14 kg.m−3) and very porous (porosity >99 %). The aerogels of BCOXNS showed better mechanical properties (tension of 13.0 kPa, modulus of elasticity of 39.4 kPa) and hydrophobicity, and could absorb organic solvents of different polarities. The BCOXNS could be recycled at least 7 times after absorbing organic solvents while retaining an absorption capacity of 83 %. This material can be used as a standard for the further development of aerogels based on bacterial biopolymers.

Harvesting Bacterial Cellulose from Kitchen Waste to Prepare Superhydrophobic Aerogel for Recovering Waste Cooking Oil toward a Closed-Loop Biorefinery

Bacterial cellulose (BC), harvested from the hydrolysate of starch-rich solid in kitchen waste (KW), was employed to prepare a superhydrophobic stearic acid (SA)-modified BC aerogel (S-BCA) for coo...

Enhanced rheological properties and conductivity of bacterial cellulose hydrogels and aerogels through complexation with metal ions and PEDOT/PSS

Bacterial cellulose (BC) based hybrid hydrogels and aerogels have been fabricated by reformatting BC pellicles. BC pellicles are formed by tight fibrillar networks making it challenging to incorporate other materials to form hybrids or composites. In this study, BC pellicles produced from two Acetobacteracea family members are disintegrated into individual nanofibrils via TEMPO-mediated oxidation. The individualized BC nanofibrils about tens of microns in length and 20–50 nm in width are well-dispersed in water with crystallinity and birefringence of cellulose I. These BC nanofibril dispersions are non-Newtonian fluid. Upon complexation with 0.75 mmol/g of Fe3+, the formed BC nanofibril hydrogels display 17-fold increase in storage moduli. Composite aerogels formed by complexation with conductive polymer PEDOT/PSS show characteristics of a non-Hookean foam material with conductivity value of up to 0.86 S/cm for cellulose density of 4.2 mg/cm2.

Nanocellulose-based Surface-enhanced Raman spectroscopy sensor for highly sensitive detection of TNT

Surface-enhanced Raman scattering (SERS) has undergone an important development in the detection and identification of extremely low traces of explosives over the past few years. Here we fabricated a new type of three-dimensional (3D) SERS sensors by loading AuNR@AgNCs on bacterial cellulose aerogels for the detection of 2, 4, 6-trinitrotoluene (TNT). The aerogel substrates with hierarchical pore structure are favored by the construction of dense 3D hot-spot distribution and the enrichment of TNT molecules. The retention aid of polyethyleneimine was used to improve the loading capacity as well as prevent the aggregation of nanoparticles. Moreover, AuNR@AgNCs were modified with p-aminobenzenethiol to improve the affinity of SERS substrates to TNT via the formation of Meisenheimer complex. Owing to the unique structure and morphology of AuNR@AgNCs, the composite SERS substrate can detect trace TNT with a limit of detection of 8 × 10−12 g/L and the SERS enhancement factor is high up to 1.87 × 108.