Biomass Aerogels Research Articles

Eliminating trade-offs between optical scattering and mechanical durability in aerogels as outdoor passive cooling metamaterials.

Passive cooling is a promising approach for reducing the large energy consumption to achieve carbon neutrality. Foams/aerogels can be considered effective daytime cooling materials due to their good solar scattering and thermal insulation capacity. However, the contradiction between the desired high solar reflectivity and mechanical performance still limits their scalable production and real application. Herein, inspired by the "Floor-Pillar" concept in the building industry, a multi-structure assembly-induced ice templating technology was used to construct all-cellulosic aerogels with well-defined biomimetic structures. By using cellulose nanofibers (CNFs) as pillars and cellulose nanocrystals (CNCs) as floors and methyltrimethoxysilane (MTMS) as a crosslinking material, an all-cellulosic aerogel (NCA) exhibiting high mechanical strength (mechanical strength = 0.3 MPa at 80% compression ratio, Young's modulus = 1 MPa), ultralow thermal conductivity (28 mW m-1 K-1), ultrahigh solar reflectance (97.5%), high infrared emissivity (0.93), as well as excellent anti-weather function can be achieved, exceeding the performance of most reported cellulosic aerogels. Furthermore, the mechanisms of the improved mechanical strength and stimulated superior solar reflectance of NCA were studied in detail using finite element simulations and COMSOL Multiphysics. As a result, the NCA can achieve a cooling efficiency of 7.5 °C during the daytime. The building energy stimulus demonstrated that 44% of cooling energy can be saved in China annually if the NCA is applied. This work lays the foundation for the preparation of biomass aerogels for energy-saving applications.

Lightweight, flame retardant Janus carboxymethyl cellulose aerogel with fire-warning properties for smart sensor

Lightweight, flame retardant biomass aerogels combining with multi-functionalities are promising for thermal insulation, noise absorption and smart sensors. However, high flammability hinders the application of these aerogels in extreme condition. Herein, lightweight, flame retardant aerogel with fire-warning properties fabricated from resource-abundant graphite and green carboxymethyl cellulose (CMC) is reported. During sonicating expandable graphite (EG) in CMC solution, CMC not only fabricates the downsizing process via hydrogen bonding effect but also forms stable dispersions. Then biomass aerogel is fabricated by freeze-drying strategy and enhanced by metal ionic cross-linking method. This aerogel demonstrates Janus properties for electrical conductivity and thermal conductivity. Due to the synergistic flame retardant effect of graphite nanocomposite and metal ions with a barrier effect and catalytic carbonization capacity, the flame retardancy of these aerogels are enhanced with fire-warning properties. Furthermore, these aerogels are used for monitoring physical deformations as smart sensors, which provides inspiration and a sustainable solution for developing low-cost biomass aerogel with multifunction.

Construction of a multifunctional dual-network chitosan composite aerogel with enhanced tunability

Typically, the tailorable versatility of biomass aerogels is attributed to the tunable internal molecular structure, providing broad application prospects. Herein, a simple and novel preparation strategy for developing multifunctional dual-network chitosan/itaconic acid (CSI) aerogel with tunability by using freeze-drying and vacuum heat treatment techniques. By regulating the temperature and duration of amidation reaction, electrostatic interactions between chitosan (CS) and itaconic acid (IA) was abstemiously converted into amide bond in frozen aerogel, with IA acting as an efficient in-situ cross-linking agent, which yielded CSI aerogels with different electrostatic/covalent cross-linking ratios. Heat treatment and tuning of the covalent cross-linking degree of CSI aerogel changed their microstructure and density, which led to enhanced performance. For example, the specific modulus of CSI1.5–160 °C-5 h (71.69 ± 2.55 MPa·cm3·g−1) increased by 119 % compared to that of CSI1.5 (32.73 ± 0.718 MPa·cm3·g−1), converting the material from superhydrophilic to hydrophobic (124° ± 3.6°), exhibiting favorable stability and heat transfer performance. In addition, part of -NH3+ of CS was retained in the electrostatic cross-linked network, endowing the aerogel with antibacterial properties. The findings of this study provide insights and a reliable strategy for fabricating biomass aerogel with good comprehensive performance via ingenious structural design and simple regulation methods.

Water-resistant nanocellulose/gelatin biomass aerogel for anionic/cationic dye adsorption

Biomass aerogels are potential adsorbent materials with abundant resources and high performance. However, biomass aerogels often suffer from poor water resistance, which is deadly for their application in water remediation. In this study, a kind of biomass aerogel with excellent water resistance was prepared by using cellulose nanofiber (CNF) and gelatin as the substrate and γ-(2,3-epoxypropoxy) propytrimethoxysilane trimethoxysilane (GPTMS) as the crosslinking agent. The composite aerogel was characterized by Fourier transform infrared, x-ray diffraction, and x-ray photoelectron spectroscopy, and the results showed that a cross-linked network formed by CNF, GPTMS, and gelatin can significantly improve the strength of the composite aerogels. The cross-linking strategy reported in this paper overcomes the defects that CNF is easily dispersed in water and gelatin is easily dissolved in water. Moreover, CNF/gelatin aerogel can adsorb both anionic and cationic dyes. And, the maximum adsorption capacity of CGK aerogel on MB and CR was 182.6 mg/g and 590.6 mg/g, respectively. The prepared aerogel can maintain excellent structural stability under acidic or alkaline conditions, which lays a foundation for its recyclability. Therefore, CGK composite aerogels may have potential applications in wastewater treatment due to their environmental sustainability.

Konjac glucomannan-based aerogels with excellent thermal stability and flame retardancy for thermal insulation application

Biomass aerogels are a promising kind of environment-friendly thermal insulation material. However, the flammability, poor water resistance, and thermal instability of biomass aerogels limit their applications. Herein, freeze-drying and thermal imidization were used to create konjac glucomannan (KGM), boron nitride (BN), and polyimide (PI)-based aerogels with a semi-interpenetrating network structure. The introduction of BN was beneficial to improve the mechanical properties and thermal stability of aerogels. The imidization process of PI improved the hydrophobicity, mechanical property, and flame retardancy of the aerogels. The synergistic effect of PI and BN reduced the peak heat release rate and total heat release rate of KGM-based aerogel by 55.8 % and 35 %, respectively, and endowed aerogel with good self-extinguishing performance. Moreover, the results of thermal conductivity and infrared thermal imaging demonstrated that the aerogels had excellent thermal insulation properties, and could effectively manage thermal energy over a wide range of temperatures. This study provides a simple method for the preparation of heat-insulating aerogel with high fire safety, which has broad application prospects in the field of energy saving and emission reduction.

Lignin with enhanced photothermal performance for the preparation of a sustainable solar-driven double-layer biomass evaporator

The undesirable photothermal conversion performance of lignin limits the potential for directing use as a photothermal conversion material, and no strategies have been found to enhance the photothermal conversion efficiency of lignin. Herein, three modified lignin of corn stover alkali lignin (DEHL), pine alkali lignin (DAL) and birch alkali lignin (DTAL) with excellent photothermal conversion efficiency and fast temperature response was prepared by a one-step iodocyclohexane (ICH) activation strategy. The maximum temperature of the DEHL, DAL and DTAL can reach to 138 °C, 157 °C, and 172 °C in 12 min under 0.15 W/cm2 compared to the native lignin. Moreover, the photothermal conversion efficiency of the DEHL, DAL and DTAL was calculated to be 36.52 %, 36.19 % and 43.19 % by ICH modification. The photothermal enhancement mechanism of the modified lignin was determined by various characterizations and simulation calculations, which can be summarized that the activation of lignin by ICH breaks the molecular structure and reduces the methoxy content of the lignin, which enhances the intermolecular bonding, and the hydrogen bonding between the phenolic hydroxyl groups strengthens the π-π intermolecular interactions between the benzene rings. In addition, a double-layer biomass aerogel evaporator (DAGS) with cost-friendly and superior evaporation performance was synthesized by chemical cross-linking using DTAL as the photothermal agent. The evaporation rate of 4DAGS can be as high as 2.063, 2.024, 2.259 and 2.447 kg/(m2∙h) in water, 3.5 wt% seawater, and 200 mg/L of MG or MB wastewater under 1sun. And no salt was observed on the surface of the 4DAGS after a long period of 36 h of operation in 3.5 wt% seawater, suggesting the outstanding salt-reject performance of the aerogel. Furthermore, there is no structural damage and chemical decomposition found on 4DAGS after 24 h immersion in NaOH and HCl solutions, demonstrating the excellent acid and alkali resistance of the synthesized aerogels. This work may offer a novel strategy for the photothermal performance enhancement of lignin and expand the potential application in solar-driven evaporation materials.

High efficiency and selective separation of oily wastewater based on superamphiphilic biomass aerogel: Characteristics, mechanisms and application

The design and development of multifunctional materials to meet the sophisticated requirements of oily wastewater treatment is an urgent need and remains a great challenge. Herein, a superamphiphilic bio-aerogel (PTGA) with honeycomb-like porous structure was synthesized. The directional and reversible control of interfacial wettability can be achieved by simple pre-wetting process and solvent replacement method. Combined with the advantages of structure and wettability, PTGA was proved to be ideal for high-efficient oil-water mixture separation (J> 1500 L/m2·h, η > 99.8%), oils absorption (Cabs = 17–26 g/g) and dye selective removal (MO: 73.552 mg/g, MB: 45.876 mg/g). Furthermore, based on the newly developed dynamic separation device and excellent mechanical property of PTGA, enhanced separation of oil-water mixture (J = 3007 L/m2·h) and synergistic removal of co-existing pollutants (MB: 51.274 mg/g) were realized. Mechanism results indicated that the transition of interfacial wetting properties of PTGA was a multi-stage process, while oil/water separation and dye adsorption were two independent processes. Benefit from facile synthesis and unparalleled characteristics, the designed PTGA promise to be reliable and competitive candidates in wastewater remediation.

Biomass aerogel composite containing BaTiO3 nanoparticles and MXene for highly sensitive self-powered sensor and photothermal antibacterial applications

Biomass aerogel materials are increasingly attracting researchers’ attention because of good biocompatibility of biomass materials and multiple functional features of aerogel materials. Herein, novel biomass aerogel composite was fabricated by doping hydroxylated barium titanate (BT-OH) nanoparticles and MXene in chitosan/bacterial cellulose (CB) aerogel by simple methods containing chemical modification, physical mixture and lyophilization. The novel aerogel composite named CB/BT-OH/MXene showed favorable piezoelectric properties and excellent photothermal antibacterial properties. The aerogel composite-based piezoelectric sensor displayed short response time (0.4 s), high response sensitivity (800 mV/N), and long cycle stability (over 1000 cycles), which could monitor various body movements, including fingers bending, speaking, wrist bending, elbow bending, smiling, and walking. Moreover, the aerogel composite possessed satisfactory photothermal conversion ability, which could reach 55 ℃ by 10 s of near-infrared irradiation (808 nm, 0.2 W/cm2), successfully achieving complete sterilization effect towards S. aureus and E. coli. The novel biomass aerogel composite may find its potential applications in wearable or implantable self-powered sensors with satisfactory antibacterial performance.

Bio-derived 1T-MoS2/C-based aerogel by synergistic solar evaporation and tetracyclines removal for efficient freshwater generation

Tetracycline, a broad-spectrum antibiotic, has been widely used in disease treatment and other fields. However, due to the unreasonable use, tetracycline residue remains in water which eventually endangers human health. The green environmental protection, low-cost, and renewability biomass aerogel are highly attractive for the purification of tetracycline wastewater. Here, the flower-like 1T-MoS2 with S vacancies was uniformly grown on the supporting poplar catkin fibers-based biomass carbon matrix, which was constructed 3D porous aerogel by ice template method. The adsorption kinetics and adsorption isotherms model of MoS2/C-based aerogel for tetracycline in wastewater was investigated, revealing a maximum adsorption capacity of 124.4 mg g−1. More notably, the MoS2/C-based aerogel displayed excellent photothermal performance, which could synergistically raise the local temperature. The solar evaporation induced transpiration was able to accelerate the adsorption of tetracycline, owing to the endothermic behavior of tetracycline adsorption process. The MoS2/C-based aerogel attained an excellent water evaporation rate of 2.54 kg m−2 h−1 under one sun illumination, which is 11 times that of pure water. The solar purification prototype-based on MoS2/C-based aerogel could effectively remove tetracycline and generate freshwater. The freshwater production was about 33.6 kg m−2, and the tetracyclines were completed removed in the generation of condensed water on sunny days. The unique bifunctional capability of the MoS2/C-based aerogel paved a new strategy for tetracycline wastewater treatment and alleviated the dilemma of global water.

Excellent thermal insulation and flame retardancy property of konjac glucomannan/sodium alginate aerogel reinforced by phytic acid

The growing social awareness of the green industry has driven the rapid development of eco-friendly insulation biomass aerogels to replace traditional ones. Natural polysaccharide aerogels have garnered significant research interest owing to their exceptional sustainability and safety. However, the challenges in achieving a harmonious combination of excellent thermal insulation and flame retardancy have impeded their practical application. In this study, a full biomass konjac glucomannan/sodium alginate aerogel was fabricated with phytic acid (PA) addition to strengthen its thermal insulation and flame retardancy properties. Results showed that the aerogel had a density of 11.8–49.2 mg/cm3 and a porosity of 95.1–98.7%. The physical cross-linking interactions of the components contributed to the formation of the pore structure. Although the analysis on the combustion, residual component, and char layer indicated a higher PA addition strengthened the flame retardancy property, it led to the appearance of micro holes on the pore wall, resulting in poorer thermal insulation properties and significantly weakened mechanical properties. Therefore the optimum PA addition was considered to be 0.25%, and the flame retardancy mechanism was proposed. The obtained aerogel exhibited a thermal conductivity as low as 0.032 W/(mK), compressive strength of 245.4 kPa, limiting oxygen index value of 29.3%, and peak heat release rate value of 21.79 W/g. These findings not only offered a kind of eco-friendly aerogel with excellent thermal insulation and flame retardancy but also contributed to the impact of PA addition on the polysaccharide aerogel structure.

Antiviral activity of salt-coated materials against SARS-CoV-2.

The SARS-CoV-2 pandemic demonstrated the importance of human coronaviruses and the need to develop materials to prevent the spread of emergent respiratory viruses. Coating of surfaces with antiviral materials is a major interest in controlling spread of viruses, especially in high-risk or high-traffic areas. A number of different coatings for surfaces have been proposed, each with their own advantages and disadvantages. Here we show that simple salt coating on a range of surfaces, including a novel biomass aerogel can reduce the infectivity of SARS-CoV-2 placed onto the surface. This suggests that a simple to apply coating could be applied to a range of materials and have an antiviral effect against SARS-CoV-2, as well as other potential emerging viruses.

Construction of carboxymethyl chitosan @ sodium oxide alginate aerogel for efficient adsorption of malachite green

AbstractWater pollution has emerged as a formidable issue of utmost concern in the world, and the design of three‐dimensional porous, high adsorption performance, and sustainable adsorbent materials is of great significance for wastewater purification. Naturally abundant sodium alginate was used to prepare oxidized sodium alginate (OSA), a biomass macromolecule containing an aldehyde group. A double network interpenetrating structure based on carboxymethyl chitosan (CMS) and OSA was constructed without any small molecule cross‐linking agent throughout, and a Schiff base reaction occurred at room temperature to prepare chemically stable CMS@OSA aerogels, which contain a continuous and dense porous structure inside the aerogel. CMS and OSA both contain an anionic reactive group, carboxyl, which makes them both matrix and functional materials, enabling selective adsorption of malachite green (MG) dyes. The prepared aerogel adsorbent showed a high adsorption capacity (302 mg/g) for MG at room temperature. The adsorption mechanism between the aerogel adsorbent and the adsorbent mass was investigated, and the effect of different factors on the adsorption performance was analyzed. The fitting coefficients of both the adsorption kinetic model and the isotherm model reached 0.99. The ingenious preparation method and excellent adsorption performance offer great prospects for chitosan biomass aerogels to play a role in environmental protection and economy.Highlights An interpenetrating structure based on the Schiff base reaction. Construction of three‐dimensional porous structures. Pure ecological raw materials without toxic crosslinkers. High adsorption capacity at 302 mg/g for malachite green.

Bacterial cellulose composite aerogel with high elasticity and adjustable wettability for dye absorption and oil–water separation

Recently, cellulose-based biomass aerogel, as a high performance adsorption material, has received considerable attention. However, it remains a huge challenge to prepare cellulose aerogels with outstanding mechanical properties by simple and environmentally-friendly strategies. Here, we describe a green one-pot method to prepare a versatile bacterial cellulose/γ-(2,3-epoxypropoxy) propytrimethoxysilane trimethoxysilane composite aerogel (BK aerogel). The elasticity of BK aerogel is significantly improved and up to 96.4% after compression under 80% strain. Further, the elastic recovery can reach 87.8% over 50 times compressions at a set strain of 80 %, implying the obtained composite aerogel possesses strong fatigue resistance. BK aerogel could be soaked in water to adsorb cationic dyes and reused without being damaged. In addition, the prepared BK aerogel is rich in hydroxyl and epoxy groups, so its surface chemistry can be further adjusted. Taking hydrophobic modification as an example, the prepared aerogel can be used for oil–water separation and reused by mechanical squeezing. This study paves a simple and green solution for developing high elastic cellulose nanofiber aerogel with adjustable surface chemistry to meet diverse applications.

Carboxymethyl cellulose/polyvinyl alcohol composite aerogel supported beta molecular sieve for CH4 adsorption and storage

Biomass aerogel is attractive in various applications due to their renewable, biodegradable and eco-friendly advantages. Herein, a novel beta molecular sieve/carboxymethyl cellulose/polyvinyl alcohol composite aerogel (beta/CP) is prepared by direct mixing and directional freeze-drying as an efficient gas adsorbent with hierarchical porosity. The beta molecular sieve is uniformly dispersed in the three-dimensional skeleton of the aerogel. By adjusting the loading mass of the beta molecular sieve to constitute a reasonable porosity and pore size distribution, the synergistic effect between pore structures of different scales improves the adsorption performance. The experiment results of beta/CP-4 show that the CH4 adsorption capacity can reach 60.33 cm3/g at 298 K and 100 bar, which is almost the same as that of the pure beta molecular sieve (62.09 cm3/g). The strong interaction between the aerogel and it prevents the molecular sieve agglomeration, improves the pore utilization, and also reduces the cost of using molecular sieve adsorbent. The above results indicate that the composite has good potential for application in the field of CH4 storage.

Preparation of aerogels from corn stalks and research on their properties and gelation behavior

Corn straw is a kind of agricultural biomass waste produced by the corn crop. It is a question of how to make effective use of this waste resource. Biomass aerogel is a good adsorbent which can be used to deal with water pollution. The direct use of non-component separated maize straw as the raw material in this paper can effectively reduce the experimental cost, simplify the experimental procedures and make efficient use of maize straw compared to traditional cellulosic raw materials. The inorganic salt lithium bromide (LiBr) solution was used as the solvent, and the environmentally friendly corn stover whole component aerogels (CA) with excellent performance were prepared by solvent replacement and freeze-drying. The optimum process for the preparation of aerogels was obtained using a single factor test method: 1:200, 150 ℃, 40 min, 70 wt% LiBr. The full-component aerogels from maize straw contained cellulose, hemicellulose and lignin, which indicated that the maize straw was effectively utilised. CA has a three-dimensional network pore structure, mainly composed of micropores and mesoporous pores. It has ultra-low density (9 mg/cm3) and excellent adsorption capacity for methylene blue and soybean oil (123.59 mg/g, 103.58 g/g). At the same time, the Rheolaser Master Microrheological (RMM) analyzer of French Formulaction Company was used to investigate the changes in solution gel process. The mean azimuth shift (MSD) curve of the sample was measured by optical microrheometer. The elastic factor (EI), macroscopic viscosity factor (MVI), solid-liquid equilibrium point (SLB), and photon free path (I*) values of the samples were calculated to explore the microstructure and rheological characteristics of the samples during the gel process. The gel behaviour and processes have been explored based on the analysis of these parameters. Potential applications of whole-component aerogels from corn stalks include building insulation, thermal insulation, light-blocking materials, and packaging materials.

Carboxylated cellulose-based aerogel with cellular pores prepared by stir freezing for cationic dye adsorption

A TEMPO-oxidized cellulose (TOC)/nanofiber cellulose (NFC) biomass aerogel was prepared through freeze-drying (FD) for cationic dye adsorption. The stir freezing method was utilized to build cellular pores so as to improve the mechanical property of aerogel. The dielectric-assisted microwave (MW) heating was adopted to increase the FD rate. The results showed that the proposed method could simultaneously intensify the mass and heat transfer of FD, reducing more than 36% of drying time. The TOC/NFC aerogel exhibited a high mechanical property with 91.36 kPa of compressive stress at 80% strain. The maximum adsorption capabilities of aerogel prepared by stir freezing for methylene blue (MB) and malachite green (MG) dyes were 248.27 and 227.30 mg·g–1, respectively. The prepared aerogel showed high selective adsorption of cationic dyes in binary dye solutions. Moreover, the prepared aerogel exhibited a satisfactory recycling performance in 20 cycles of adsorption/desorption experiments. This work provides a new freezing and FD strategy to prepare TOC/NFC aerogels with promising applications in industrial printing and dyeing wastewater treatment.

Bacterial cellulose biomass aerogels for oil-water separation and thermal insulation

The use of environment-friendly biomass for the preparation of functional materials has attracted increasing attention. In this study, bacterial cellulose (BC) was prepared from fruit waste via kombucha fermentation without involving any secondary enzymatic hydrolysis treatments. A three-dimensional network of bacterial cellulose aerogels (BCAs) with ultralow density (5.693 mg/cm3), high porosity (98–99%), and low thermal conductivity (23.4 mW/(m·K)) were obtained using two directional freeze-drying techniques. Here, the proposed freezing method can not only control the concentration of BC but make access to fibres reassembly by extremely low temperature freezing (−196 °C), which can further form a multi-stage pore structure. To increase their compressive resistance and optimise their ability to adsorb organic solvents and oils, the aerogels were subjected to chemical vapour deposition using methyltrimethoxysilane. The modified biomass aerogel exhibits a compression resilience exceeding 90% and achieves a hydrophobic angle of approximately 146.4°. This cost-effective, environmentally friendly, and highly efficient BCAs can be employed to treat oil spills and industrial waste.

Carnauba Wax‐Assisted Preparation of Eco‐Friendly Aerogels by the Ambient Pressure Drying Method and their Applications for Photothermal Evaporation and Dye Wastewater Treatment

AbstractIn this study, a new, eco‐friendly, and efficient method to prepare aerogels using nonchemically cross‐linked agar gels is described. This new process could eventually facilitate the rapid, continuous, and large‐scale production of porous and lightweight materials, as it does not require freeze‐drying, supercritical drying, or environmentally harmful crosslinking chemicals. The reported preparation process relies entirely on targeted freezing, solvent exchange, and the ambient pressure drying of agar gels. The obtained results revealed that biomass aerogels with good shapes can be obtained by simple directional freezing and that the introduction of carnauba wax solutes can maintain a highly porous structure throughout the process. The directionally grown anisotropic gels with excellent void space, anisotropic thermal conductivity, and excellent mechanical compression properties demonstrate immense potential for water treatment, controlled release of active compounds, thermal insulation, and catalysis. PDA‐loaded aerogels exhibit excellent performance for photothermal evaporation and dye wastewater treatment, with high evaporation rates and photothermal efficiencies of 2.83 kg m−2 h−1 and 92.27%, respectively, and a dye removal efficiency of 94.5%. Hence, these aerogels demonstrate immense potential for applications in water treatment.

Janus biomass aerogel for Highly-Efficient steam Generation, Desalination, degradation of organics and water disinfection

Solar-driven water purification has been deemed as a cheap, green and renewable technology to mitigate water shortage and pollution. Herein, a biomass aerogel with hydrophilic-hydrophobic Janus structure has been prepared as solar water evaporator, which is achieved by partially modifying hydrothermal-treated loofah sponge (HLS) with reduced graphene oxide (rGO). It's a rare design philosophy that HLS serves as a substrate with large pores and hydrophilic properties to ensure continuous and effective water transport, and the hydrophobic layer with rGO modification guarantees good salt resistance in seawater desalination with high photothermal conversion efficiency. As a result, the obtained Janus aerogel, p-HLS@rGO-12, exhibits impressive solar-driven evaporation rates of 1.75 kg m-2h−1 and 1.54 kg m-2h−1 for pure water and seawater respectively, with good cycling stability in the evaporation process. Furthermore, p-HLS@rGO-12 also demonstrates outstanding photothermal degradation of rhodamine B (greater than98.8 % in 2 h) and sterilization of E. coli (nearly 100 % in 2 h). This work offers an unusual approach to achieve highly efficient solar-driven steam generation, seawater desalination, organic pollutant degradation, and water disinfection simultaneously. The prepared Janus biomass aerogel holds great potential application in the field of seawater desalination and wastewater purification.

Preparation of antifouling and highly hydrophobic cellulose nanofibers/alginate aerogels by bidirectional freeze-drying for water-oil separation in the ocean environment.

Oil spills frequently occur in the ocean, and adsorption is one of the effective ways to deal with oil spills. Compared with other adsorbent materials, biomass aerogel has superior selective adsorption capacity. CNF/SA aerogels with good mechanical properties (340kPa at 90 % strain) and high adsorption capacity (88.91g/g) were prepared by mixing cellulose nanofibers (CNF) with sodium alginate (SA) through bidirectional freeze-drying, ionic crosslinking, and surface modification to effectively solve the ocean oil spill problem. The bidirectional freeze-drying technology is a green and efficient technique for preparing layered microstructured composite aerogels. The prepared aerogels have a three-dimensional interpenetrating lamellar structure, low density (24.2mg/cm3), high porosity (97.85 %), and high hydrophobicity (WCA=144.5°), can be calibrated and used repeatedly. It has potential applications in water-oil separation and can be used as an absorbent for effectively treating oil spills in the ocean environment.