Multifunctional Cellulose Nanopaper with Superior Water-Resistant, Conductive, and Antibacterial Properties Functionalized with Chitosan and Polypyrrole

Recent advance on lignin-containing nanocelluloses: The key role of lignin

Nanocelluloses (NCs) isolated from lignocellulosic resources usually require harsh chemical pretreatments to remove lignin, which face constraints such as high energy consumption and inefficient resource utilization. An alternative strategy involving the partial retention of lignin can be adopted to endow NCs with better versatility and functionality. The resulting lignin-containing nanocelluloses (LNCs) generally possess better mechanical property, thermal stability, barrier property, antioxidant activity, and surface hydrophobicity than lignin-free NCs, which have attracted extensive interest as a promising green nanomaterial for numerous applications. This review provides a comprehensive overview of the recent advances in the preparation, properties, and food application of LNCs. The effect of residual lignin on the preparation and properties of LNCs is discussed. Furthermore, the key roles of lignin in the properties of LNCs, including particle size, crystalline structure, dispersibility, thermal, mechanical, antibacterial, rheological and adhesion properties, are summarized comprehensively. Furthermore, capitalizing on their dietary fiber and nanostructure properties, the food applications of LNCs in the forms of films, gels and emulsions are also discussed. Finally, the challenges and opportunities regarding the development of LNCs are provided.

Advances in the preparation and application of cellulose-based antimicrobial materials: A review

The rise of polymer materials in modern life has drawn attention to renewable, easily biodegradable, environmentally-friendly bio-based polymers. Notably, significant research has been dedicated to creating green antimicrobial functional materials for the biomedical field using natural polymer materials. Cellulose is a rich natural biomass organic polymer material. Given its favorable attributes like film-forming capability, biodegradability, and biocompatibility, it is extensively employed to tackle a wide range of challenges confronting humanity today. However, its inherent drawbacks, such as insolubility in water and most organic solvents, hygroscopic nature, difficulty in melting, and limited antimicrobial properties, continue to pose challenges for realizing the high-value applications of cellulose. Achieving multifunctionality and more efficient application of cellulose still poses major challenges. In this regard, the current development status of cellulose materials was reviewed, covering the classification, preparation methods, and application status of cellulose-based antimicrobial materials. The application value of cellulose-based antimicrobial materials in biomedicine, textiles, food packaging, cosmetics and wastewater treatment was summarised. Finally, insights were provided into the developing prospects of cellulose-based antimicrobial materials were provided.

Nanocellulose-based conductive composites: A review of systems for electromagnetic interference shielding applications

Electronic systems and telecommunications have grown in popularity, leading to increasing electromagnetic (EM) radiation pollution. Environmental protection from EM radiation demands the use of environmentally friendly products. The design of EM interference (EMI) shielding materials using resources like nanocellulose (NC) is gaining traction. Cellulose, owing to its biocompatibility, biodegradability, and excellent mechanical and thermal properties, has attracted significant interest for developing EMI shielding materials. Recent advancements in cellulose-based EMI shielding materials, particularly modified cellulosic composites, are highlighted in this study. By incorporating metallic coatings compounded with conductive fillers and modified with inherently conductive elements, conductivity and effectiveness of EMI shielding can be significantly improved. This review discusses the introduction of EMI shields, cellulose, and NC, assessing environmentally friendly EMI shield options and diverse NC-based composite EMI shields considering their low reflectivity. The study offers new insights into designing advanced NC-based conductive composites for EMI shielding applications.

Fabrication of N-halamine/MWPPy-ZnO hybrids based cellulose nanofibril composite films with improved UV-protective, antibacterial, and biofilm control functions

The design and fabrication of synergistic hybrid antibacterial materials is a promising approach for achieving effective sterilization while compensating for the deficiency of a single component. Despite being highly effective biocidal components, the poor UV light stability of some N-halamines limits their applications. This study was conducted to address this issue by the rational integration of cyclic N-halamine precursor (PGHAPA) with microwaved zinc oxide (MWPPy-ZnO) nanoparticles via covalent bonds and the preparation of cellulose nanofibrils based antibacterial composite films after chlorination (CNF/MWPPy-ZnO-PGHAPA-Cl). The proposed films offered tight lamellar structure, considerable thermal stability and better mechanical properties. The results from the FT-IR and XPS experiments provided the evidence of chemical reactions among the PGHAPA, MWPPy-ZnO, and CNF film. Notably, the CNF/MWPPy-ZnO-PGHAPA-Cl films showed improved UV stability with a chlorine content of up to 0.16 % after 24 h of irradiation, which was much greater than that of the CNF/PGHAPA-Cl films. Furthermore, the CNF/MWPPy-ZnO-PGHAPA-Cl films displayed rapid bactericidal activity, inactivating all the contacted Staphylococcus aureus and Escherichia coli O157:H7 strains within 5 min, along with prominent biofilm disruption, indicating great potential for daily food packaging applications.

Ultrathin and highly flexible layered silver nanowires/carboxymethyl cellulose nanofiber nanocomposite films for electromagnetic interference shielding

Lightweight, flexible, efficient and easy-to-manufacture electromagnetic interference (EMI) shielding materials are in urgent demand in the communications industry, artificial intelligence and wearable electronics. Based on the large size difference between one-dimensional carboxymethyl cellulose nanofibers (CMC) and large-diameter silver nanowires (AgNWs), layered AgNWs/CMC nanocomposite films with large effective thickness, and high conductivity were first prepared by a simple one-step vacuum filtration self-assembly technique. The unique layered structure of the AgNWs/CMC nanocomposite film significantly enhances the conductive pathways within the film, endowing it excellent EMI shielding performance. The results show that the conductivity of the ultra-thin film with a thickness of 20 μm is 3.72 × 106 S/m, and the EMI SE in the X-band is 87.7 dB, which can effectively shield electromagnetic signals in mobile communications. Furthermore, the AgNWs/CMCs nanocomposite films exhibit excellent thermal management performance, which can be heated to 100-180 °C within 10 s at a low voltage of 1.5 V. In particular, this nanocomposite film with a new layered structure provides a noval preparation idea for future EMI shielding materials and wearable heating devices.

Cellulose-derived raw materials towards advanced functional transparent papers

Pulp and paper are gradually transforming from a traditional industry into a new green strategic industry. In parallel, cellulose-derived transparent paper is gaining ground for the development of advanced functional materials for light management with eco-friendly, high performance, and multifunctionality. This review focuses on methods and processes for the preparation of cellulose-derived transparent papers, highlighting the characterization of raw materials linked to responses to different properties, such as optical and mechanical properties. The applications in electronic devices, energy conversion and storage, and eco-friendly packaging are also highlighted with the objective to showcase the untapped potential of cellulose-derived transparent paper, challenging the prevailing notion that paper is merely a daily life product. Finally, the challenges and propose future directions for the development of cellulose-derived transparent paper are identified.

Fabrication of flame-retardant and water-resistant nanopapers through electrostatic complexation of phosphorylated cellulose nanofibers and chitin nanocrystals

Biogenic, sustainable two-dimensional architectures, such as films and nanopapers, have garnered considerable interest because of their low carbon footprint, biodegradability, advanced optical/mechanical characteristics, and diverse potential applications. Here, bio-based nanopapers with tailored characteristics were engineered by the electrostatic complexation of oppositely charged colloidal phosphorylated cellulose nanofibers (P-CNFs) and deacetylated chitin nanocrystals (ChNCs). The electrostatic interaction between anionic P-CNFs and cationic ChNCs enhanced the stretchability and water stability of the nanopapers. Correspondingly, they exhibited a wet tensile strength of 17.7 MPa after 24 h of water immersion. Furthermore, the nanopapers exhibited good thermal stability and excellent self-extinguishing behavior, triggered by both phosphorous and nitrogen. These features make the nanopapers sustainable and promising structures for application in advanced fields, such as optoelectronics.

Heat-triggered shape recovery, EMI shielding and flame retardant: A novel cellulose/M(OH)(OCH3)@dopamine@Ag (M=Co, Ni) nanopaper for early fire alarm

Fire alarm systems are essential for protecting lives and properties from fire hazards. However, most of the existing fire alarm nanopapers rely on the resistance reduction after heating, which requires direct contact with the flame. In this study, we present a novel fire alarm nanopaper (CMPA) based on heat-triggered shape recovery. The CMPA is composed of hydroxypropyl methyl cellulose (HPMC) as the matrix and 2D nanomaterials M(OH)(OCH3) as fillers. When the temperature of CMPA exceeded the glass transition, the thrice-folded CMPA-1.0 flattened in 30s and connected to the alarm circuit based on its conductive surface. According to the results, the CMPA-1.0 with a thickness of about 0.2 mm had an efficient electromagnetic shielding of 42.1 dB. Moreover, the CMPA-1.0 self-extinguished rapidly after being ignited with its original shape preserved. The peak heat release rate of CMPA-1.0 was 108.9 W/g, which was 61.9 % lower than that of HPMC. Furthermore, the thermal conductivity of CMPA-1.0 reached to 0.317 W m-1 K-1, which was 40.8 % higher than that of HPMC, reducing the heat accumulation effectively. This work shows that CMPA is an ideal material for sensitive and safe early fire alarm, and the strategy based on heat-triggered shape recovery is promising in fire alarm application.

Enabling Further Organic Electrolyte Infiltration of Cellulose-Based Separators via Defect-Rich Polypyrrole Modification for High Sodium Ion Transport in Sodium Metal Batteries

Sodium metal batteries (SMBs) have high-density and cost-effective characteristics as one of the energy storage systems, but uncontrollable dendrite growth and poor rate performance still hinder their practical applications. Herein, a nitrogen-rich modified cellulose separator with released abundant ion transport tunnels in organic electrolyte was synthesized by in situ polymerization of polypyrrole, which is based on the high permeability of cellulose in aqueous solution and the interfacial interaction between cellulose and polypyrrole. Meanwhile, the introduction of abundant structural defects such as branch chains, oxygen-containing functional groups, and imine-like structure to disrupt polypyrrole conjugation enables the utilization of conductive polymers in composite separator applications. With the electrolyte affinity surface on, the modified separator exhibits reinforced electrolyte uptake (254%) and extended electrolyte wettability, thereby leading to accelerated ionic conductivity (2.77 mS cm-1) and homogeneous sodium deposition by facilitating the establishment of additional pathways for ion transport. Benefiting from nitrogen-rich groups, the polypyrrole-modified separator demonstrates selective Na+ transport by the data of improved Na+ transference number (0.62). Owing to the above advantages, the battery assembled with the modified separators exhibits outstanding rate performance and prominent capacity retention two times that of the pristine cellulose separator at a high current density under the condition of fluorine-free electrolyte.

Nanocellulose-graphene composites: Preparation and applications in flexible electronics

In recent years, the pursuit of high-performance nano-flexible electronic composites has led researchers to focus on nanocellulose-graphene composites. Nanocellulose has garnered widespread interest due to its exceptional properties and unique structure, such as renewability, biodegradability, and biocompatibility. However, nanocellulose materials are deficient in electrical conductivity, which limits their applications in flexible electronics. On the other hand, graphene boasts remarkable properties, including a high specific surface area, robust mechanical strength, and high electrical conductivity, making it a promising carbon-based nanomaterial. Consequently, research efforts have intensified in exploring the preparation of graphene-nanocellulose flexible electronic composites. Although there have been studies on the application of nanocellulose and graphene, there is still a lack of comprehensive information on the application of nanocellulose/graphene in flexible electronic composites. This review examines the recent developments in nanocellulose/graphene flexible electronic composites and their applications. In this review, the preparation of nanocellulose/graphene flexible electronic composites from three aspects: composite films, aerogels, and hydrogels are first introduced. Next, the recent applications of nanocellulose/graphene flexible electronic composites were summarized including sensors, supercapacitors, and electromagnetic shielding. Finally, the challenges and future directions in this emerging field was discussed.

The Alphabet of Nanostructured Polypyrrole

This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation of the ordered structure is dictated by the ability of the local forces and effects to induce restraints that help shape the structure. This review covers the aspects of morphology and roughness and their impact on the final properties of the modified electrode activity in selected applications.

Nanocellulose-based porous materials: Regulation and pathway to commercialization in regenerative medicine

We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure-property-function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.

Eco-friendly cellulose-based hydrogel functionalized by NIR-responsive multimodal antibacterial polymeric ionic liquid as platform for promoting wound healing

With the trend of sustainable development and the complex medical environment, there is a strong demand for multimodal antibacterial cellulose wound dressing (MACD) with photothermal therapy (PTT). Herein, a novel MACD fabrication strategy with PTT was proposed and implemented through graft polymerization of an imidazolium ionic liquid monomer containing iron complex anion structure. The fabricated hydrogels exhibited excellent antibacterial properties because of the efficient photothermal conversion ability (68.67 %) of ionic liquids and the intrinsic structural characteristic of quaternary ammonium salts. The antibacterial ratio of cellulosic hydrogel dressings to S. aureus and E. coli could reach 99.57 % and 99.16 %, respectively. Additionally, the fabricated hydrogels demonstrated extremely low hemolysis rates (<5 %) and excellent cell viability (~>85 %). Furthermore, in vivo antibacterial experimental results proved that the fabricated antibacterial dressings could significantly accelerate wound healing. Therefore, the proposed strategy would provide a new method of designing and preparing high-performance cellulose wound dressings.

A comprehensive review of chitosan applications in paper science and technologies

Using environmentally friendly biomaterials in different aspects of human life has been considered extensively. In this respect, different biomaterials have been identified and different applications have been found for them. Currently, chitosan, the well-known derivative of the second most abundant polysaccharide in the nature (i.e., chitin), has been receiving a lot of attention. This unique biomaterial can be defined as a renewable, high cationic charge density, antibacterial, biodegradable, biocompatible, non-toxic biomaterial with high compatibility with cellulose structure, where it can be used in different applications. This review takes a deep and comprehensive look at chitosan and its derivative applications in different aspects of papermaking.

Design, optimization and characterization of a novel antibacterial chitosan-based hydrogel dressing for promoting blood coagulation and full-thickness wound healing: A biochemical and biophysical study

The use of hydrogel dressings has become increasingly popular as a scaffold for skin tissue engineering. Herein, we have developed an innovative wound dressing using chitosan, fibrinogen, nisin, and EDTA as an effective antibacterial scaffold for wound treatment. The structural and functional characteristics of the hydrogel, including morphology, mechanical strength, drug encapsulation and release, swelling behaviors, blood coagulation, cytotoxicity, and antibacterial activity, were studied. Spectroscopic studies indicated that the attachment of chitosan to fibrinogen is associated with minimal change in its secondary structure; subsequently, at higher temperatures, it is expected to preserve fibrinogen's conformational stability. Mechanical and blood coagulation analyses indicated that the incorporation of fibrinogen into the hydrogel resulted in accelerated clotting and enhanced mechanical properties. Our cell studies showed biocompatibility and non-toxicity of the hydrogel along with the promotion of cell migration. In addition, the prepared hydrogel indicated an antibacterial behavior against both Gram-positive and Gram-negative bacteria. Interestingly, the in vivo data revealed enhanced tissue regeneration and recovery within 17 days in the studied animals. Taken together, the results obtained from in vitro and histological assessments indicate that this innovatively designed hydrogel shows good potential as a candidate for wound healing.

Collaboration of two-star nanomaterials: The applications of nanocellulose-based metal organic frameworks composites

Nanocellulose, as the star nanomaterial in carbohydrate polymers, has excellent mechanical properties, biodegradability, and easy chemical modification. However, further practical applications of nanocellulose are limited by their inadequate functionalization. Metal-organic frameworks (MOFs), as the star nanomaterial in functional polymers, have a large surface area, high porosity, and adjustable structure. The collaboration of nanocellulose and MOFs is a desirable strategy to make composites especially interesting for multifunctional and multi-field applications. What sparks will be produced by the collaboration of two-star nanomaterials? In this review article, we highlight an up-to-date overview of nanocellulose-based MOFs composites. The sewage treatment, gas separation, energy storage, and biomedical applications are mainly summarized. Finally, the challenges and research trends of nanocellulose-based MOFs composites are prospected. We hope this review may provide a valuable reference for the development and applications of carbohydrate polymer composites soon.

Hemicellulose-based hydrogels for advanced applications

Hemicellulose-based hydrogels are three-dimensional networked hydrophilic polymer with high water retention, good biocompatibility, and mechanical properties, which have attracted much attention in the field of soft materials. Herein, recent advances and developments in hemicellulose-based hydrogels were reviewed. The preparation method, formation mechanism and properties of hemicellulose-based hydrogels were introduced from the aspects of chemical cross-linking and physical cross-linking. The differences of different initiation systems such as light, enzymes, microwave radiation, and glow discharge electrolytic plasma were summarized. The advanced applications and developments of hemicellulose-based hydrogels in the fields of controlled drug release, wound dressings, high-efficiency adsorption, and sensors were summarized. Finally, the challenges faced in the field of hemicellulose-based hydrogels were summarized and prospected.

Strong, flexible, and highly conductive cellulose nanofibril/PEDOT:PSS/MXene nanocomposite films for efficient electromagnetic interference shielding

Flexible and light weight electromagnetic interference (EMI) shielding materials with high electromagnetic shielding efficiency (SE) and excellent mechanical strength are highly demanded for wearable and portable electronics. In this work, for the first time, a freestanding and flexible cellulose nanofibril (CNF)/PEDOT:PSS/MXene (Ti₃C₂T_x) nanocomposite film with a ternary heterostructure was manufactured using a vacuum-assisted filtration process. The results show that compared with pure MXene films, the tensile strength of the optimized nanocomposite film increases from 8.88 MPa to 59.99 MPa, and the corresponding fracture strain increases from 0.87% to 4.60%. Intriguingly, the optimized nanocomposite film exhibited an impressive conductivity of 1903.2 S cm^-1, which is among the highest values reported for MXene and cellulose-based nanocomposites. Owing to the superior conductivity and unique heterostructure, the nanocomposite film exhibits a high EMI SE value of 76.99 dB at a thickness of only 58.0 μm. Taking into account the robust mechanical properties and remarkable EMI shielding performance, the CNF/PEDOT:PSS/MXene nanocomposite film could be a prospective EMI shielding material for a variety of high-end applications.

Nanocellulose/two dimensional nanomaterials composites for advanced supercapacitor electrodes

With the emerging of the problems of environmental pollution and energy crisis, the development of high-efficiency energy storage technology and green renewable energy is imminent. Supercapacitors have drawn great attention in wearable electronics because of their good performance and portability. Electrodes are the key to fabricate high-performance supercapacitors with good electrochemical properties and flexibility. As a biomass based derived material, nanocellulose has potential application prospects in supercapacitor electrode materials due to its biodegradability, high mechanical strength, strong chemical reactivity, and good mechanical flexibility. In this review, the research progress of nanocellulose/two dimensional nanomaterials composites is summarized for supercapacitors in recent years. First, nanocellulose/MXene composites for supercapacitors are reviewed. Then, nanocellulose/graphene composites for supercapacitors are comprehensively elaborated. Finally, we also introduce the current challenges and development potential of nanocellulose/two dimensional nanomaterials composites in supercapacitors.

Effects of taxifolin from enzymatic hydrolysis of Rhododendron mucrotulatum on hair growth promotion

Flavonoid aglycones possess biological activities, such as antioxidant and antidiabetic activities compared to glycosides. Taxifolin, a flavonoid aglycones, is detected only in trace amounts in nature and is not easily observed. Therefore, in this study, to investigate the hair tonic and hair loss inhibitors effect of taxifolin, high content of taxifolin aglycone extract was prepared by enzymatic hydrolysis. Taxifolin effectively regulates the apoptosis of dermal papilla cells, which is associated with hair loss, based on its strong antioxidant activities. However, inhibition of dihydrotestosterone (DHT), which is a major cause of male pattern hair loss, was significantly reduced with taxifolin treatment compared with minoxidil, as a positive control. It was also confirmed that a representative factor for promoting hair growth, IGF-1, was significantly increased, and that TGF-β1, a representative biomarker for hair loss, was significantly reduced with taxifolin treatment. These results suggest that taxifolin from enzymatic hydrolysis of RM is a potential treatment for hair loss and a hair growth enhancer.

Surface Engineering of Nanomaterials with Polymers, Biomolecules, and Small Ligands for Nanomedicine

Nanomedicine is a speedily growing area of medical research that is focused on developing nanomaterials for the prevention, diagnosis, and treatment of diseases. Nanomaterials with unique physicochemical properties have recently attracted a lot of attention since they offer a lot of potential in biomedical research. Novel generations of engineered nanostructures, also known as designed and functionalized nanomaterials, have opened up new possibilities in the applications of biomedical approaches such as biological imaging, biomolecular sensing, medical devices, drug delivery, and therapy. Polymers, natural biomolecules, or synthetic ligands can interact physically or chemically with nanomaterials to functionalize them for targeted uses. This paper reviews current research in nanotechnology, with a focus on nanomaterial functionalization for medical applications. Firstly, a brief overview of the different types of nanomaterials and the strategies for their surface functionalization is offered. Secondly, different types of functionalized nanomaterials are reviewed. Then, their potential cytotoxicity and cost-effectiveness are discussed. Finally, their use in diverse fields is examined in detail, including cancer treatment, tissue engineering, drug/gene delivery, and medical implants.

Cellulose Nanopaper: Fabrication, Functionalization, and Applications

Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices, food packaging, biomedical application, and so forth, owing to their various advantages such as good flexibility, tunable light transmittance, high thermal stability, low thermal expansion coefficient, and superior mechanical properties. Herein, recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies. We begin with a brief introduction of the three types of nanocellulose: cellulose nanocrystals, cellulose nanofibrils and bacterial cellulose, recapitulating their differences in preparation and properties. Then, the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared. Furthermore, the advanced applications of cellulose nanopaper including energy storage, electronic devices, water treatment, and high-performance packaging materials were highlighted. Finally, the prospects and ongoing challenges of cellulose nanopaper were summarized.

Lignin-Based/Polypyrrole Carbon Nanofiber Electrode With Enhanced Electrochemical Properties by Electrospun Method

Tailoring the structure and properties of lignin is an important step toward electrochemical applications. In this study, lignin/polypyrrole (PPy) composite electrode films with microporous and mesoporous structures were designed effectively by electrostatic spinning, carbonization, and in situ polymerization methods. The lignin can not only reduce the cost of carbon fiber but also increase the specific surface area of composite films due to the removal of carbonyl and phenolic functional groups of lignin during carbonization. Besides, the compact three-dimensional (3D) conductive network structures were constructed with PPy particles densely coated on the lignin nanofibers, which was helpful to improve the conductivity and fast electron transfer during the charging and discharging processes. The synthesized lignin carbon fibers/PPy anode materials had good electrochemical performance in 1 M H2SO4 electrolyte. The results showed that, at a current density of 1 A g−1, the lignin carbon nanofibers/PPy (LCNFs/PPy) had a larger specific capacitance of 213.7 F g−1 than carbon nanofibers (CNFs), lignin carbon nanofibers (LCNFs), and lignin/PPy fiber (LPAN/PPy). In addition, the specific surface area of LCNFs/PPy reached 872.60 m2 g−1 and the average pore size decreased to 2.50 nm after being coated by PPy. Therefore, the independent non-binder and self-supporting conductive film is expected to be a promising electrode material for supercapacitors with high performance.

Corrosion protection of aluminum alloy (AA2219-T6) using sulfonic acid-doped conducting polymer coatings

Incorporation of organic materials into polypyrrole and polyaniline matrices to reinforce their anticorrosive properties for the protection of aluminum alloys.

The Kinetics Studies on Hydrolysis of Hemicellulose

The kinetics studies is of great importance for the understanding of the mechanism of hemicellulose pyrolysis and expanding the applications of hemicellulose. In the past years, rapid progress has been paid on the kinetics studies of hemicellulose hydrolysis. In this article, we first introduced the hydrolysis of hemicelluloses via various strategies such as autohydrolysis, dilute acid hydrolysis, catalytic hydrolysis, and enzymatic hydrolysis. Then, the history of kinetic models during hemicellulose hydrolysis was summarized. Special attention was paid to the oligosaccharides as intermediates or substrates, acid as catalyst, and thermogravimetric as analyzer method during the hemicellulose hydrolysis. Furthermore, the problems and suggestions of kinetic models during hemicellulose hydrolysis was provided. It expected that this article will favor the understanding of the mechanism of hemicellulose pyrolysis.

Preparation and Application in Water Treatment of Magnetic Biochar

This paper reviews the preparation of magnetic biochar and its application in wastewater treatment, and briefly discusses the adsorption mechanism of biochar to remove pollutants and the modification methods of biochar. Due to the good physical and chemical properties of biochar, including its rough porous structure, it has been widely used to absorb pollutants from water. Magnetic biochar is commonly prepared by combining biochar with magnetic material. The biochar is endowed with the characteristics of the magnetic material, which could effectively solve the problems of difficult recovery and easy loss of adsorbent in water treatment. Magnetic biochar with high carbon content, large specific surface area, magnetic separation, and other excellent properties, has become a hot research topic in recent years. The preparation methods and application properties of magnetic biochar are reviewed. The future research directions of magnetic biochar are put forward to provide directions for further research and application of magnetic biochar materials.