As a natural material with good biocompatibility and biodegradability, nano-cellulose has unique structure and excellent mechanical properties. It has been widely used in the construction of electrochemical energy storage system of lithium-ion batteries(LIBs), and has made significant progress. This thesis provided an overview of the preparation and modification methods of cellulose nanofibrils(CNF), cellulose nanocrystals(CNC) and bacterial cellulose(BC) in the context of the application of advanced energy storage devices LIBs and green materials nanocellulose, and reviewed the research progress on the application of nanocellulose in the field of LIBs. It was mainly divided into three aspects: first, nanocellulose-based flexible LIBs electrodes; second, carbon materials derived from nano cellulose as electrodes; third, nano cellulose derived battery separator. Finally, some problems in this field were analyzed, summarized and prospected.
Anthocyanin is a kind of flavonoid which mainly exists in plants. It has strong biological activities such as anti-cancer and anti-oxidation, and is widely used in the field of nutrition and health care. Most anthocyanins are extracted directly from plants by physical or chemical means, but the yield is low, and the extracted anthocyanins are mostly mixtures due to the restrictions of time, region and season. Biosynthesis of anthocyanins have attracted much attention by researchers worldwide in recent years. As the biosynthesis of anthocyanins can be controlled artificially and the purity of the obtained products is high, it has been widely studied. Anthocyanins cannot exist stably in the environment, and need to be modified by glycosylation, acylation and methylation to increase their stability. The modified anthocyanins can be synthesized by microorganisms and significant color changes can be seen in the medium. The biosynthesis and modification of anthocyanins were reviewed in this paper, and the preparation technology of anthocyanin synthesis from plants and microorganisms was briefly introduced, the factors affecting anthocyanin synthesis were analyzed, and finally the future research direction of anthocyanin was predicted.
5-Hydroxymethylfurfural (HMF) is one of the most important biomass-based platform molecules and widely used in the preparation of multifunctional compounds such as fine chemicals, key pharmaceutical intermediates, functional polyesters, solvents and liquid fuels. At present, the preparation of HMF is a hot spot in the field of biomass research, and the raw materials and methods for preparing HMF have been continuously expanded. This paper reviews the main preparation methods and research progress of HMF. Catalysis systems for HMF preparation is systematically described, including the types of the catalysts (mineral acids, ionic liquids, metal chlorides, solid acids and others) used in the catalytic process and the solvent systems. Then, the preparation paths and applications of important derivatives from HMF are summarized. Finally, suggestions for future research on HMF are provided based on the understanding of problems existing in the current research.
The hydrophilic, ductile, thermoplastic and biodegradable properties of cellulose acetate (CA) were introduced, and the basic structure and market application of three kinds of cellulose acetate were summarized.It was pointed out that CA still had some disadvantages such as poor thermal stability at high temperature, low mechanical strength and easily being contaminated. The impacts of the physical modification and chemical modification on the properties of CA were also reassessed.It could conclude that the chemical reaction with polymer could change the structure or properties of CA.The fouling resistance, thermoplastic, selective and reuse of the CA were improved greatly, while the physical modification could improve the porosity and thermal stability of CA membrane, and the membrane mechanical strength, metal ion exclusion rate and the water flux were improved. The applications of CA in seawater desalination, adsorption of toxic substances in flue gas, preparation of biomedical membrane, drug delivery, tissue repair and regeneration, biosensor, outdoor protection and air purification were also summarized, and the market prospect and development trend of CA were prospected.
Lignin is the most abundant renewable aromatic polymer in nature, which complex structure and compact connection with cellulose and hemicellulose through covalent bond and hydrogen bond make it difficult to be separated efficiently. Deep eutectic solvents (DES) is a novel kind of green ionic liquid, which has been successfully applied to lignin isolation due to its unique physical and chemical properties. The research progress of dissolution and extraction of lignin by deep eutectic solvents (DES) is reviewed in detail. From the point of view of the mechanism of dissolving lignin by DES, the effects of different factors(composition, proportion, pH value, functional groups of DES, water content of system, raw material, reaction time, temperature, catalyst, co-solvent, and so on) on lignin removal were emphatically expounded. Based on the research progress of DES in lignin extraction, the research progress and futuer application of lignin extraction were summarized and prospected.
With the depletion of petroleum resources and the increasingly serious white pollution, the preparation of bio-based poly(ethylene 2, 5-furandicarboxylate)(PEF) from lignocellulosic resources has become one of the research hotspots in the fields of biorefinery and green chemical industry. Compared with petroleum-based plastics, such as poly(ethylene terephthalate)(PET) and polycarbonate(PC), PEF not only has excellent thermal properties and mechanical strength, but also has more obvious advantages in gas barrier properties, which is considered as a perfect substitute for PET. However, PEF also has some drawbacks, including low elongation at break, dark color, difficult degradation and slow deep crystallization speed. Therefore, it is necessary to modify PEF before practical application. In this paper, the research progresses of PEF modification, including copolymerization, blending and other modification methods were reviewed. The effects of different diols or diacid modified monomers, catalyst types, reaction modes, additives on the properties of PEF were summarized, and the developing trend and application prospects of modified PEF were discussed.
Lignin is an amorphous, highly cross-linked polyphenol aromatic polymer with a wide range of sources and rich carbon content, and is suitable for the preparation of porous carbon materials. Using lignin to prepare porous carbon is an important way to solve the problem that lignin is difficult to be used efficiently. It can solve environmental pollution and realize resource utilization. This article mainly introduced the research status of the preparation of microporous activated carbon with lignin as carbon precursor by physical and chemical activation method and the preparation of mesoporous carbon materials by template method in recent years. The pore structure and morphology of porous carbon materials prepared by different methods were compared and analyzed, as well as their application progress in adsorption, catalysis and electrochemistry.
Firstly, this review introduced the research background and application status of bio-based hydrogels. According to the different crosslinking mechanisms, physical and chemical hydrogels were classified and described. Then, the hydrogels prepared from cellulose, chitosan, protein and other bio-based materials were summarized based on the classification of the used biomass, including the solvents system of cellulose, the preparation of cellulose-based hydrogels and modification of cellulose derivatization. Also, the feedstock sources and modification methods of chitosan-based hydrogels, as well as cross-linking mechanisms such as electrostatic interaction and imine bond formed by amine groups on their molecular chains were assembled. Protein-based hydrogels with good biocompatibility and bioactivity, formed by β-folded self-assembly of polypeptide chains were depicted as well in this review. Similarly, bio-based hydrogels prepared by using physical or chemical crosslinking of hydrophilic natural polymers such as starch, sodium alginate and carrageenan, were introduced respectively. At the same time, the main applications of functionalized bio-based hydrogels in the biomedical fields were described in detail, including drug sustained release, targeted delivery, cell media, tissue repair scaffolds, wound dressings, etc. In addition, the application and research progress of bio-based hydrogels as adsorbent materials in environmental field were reviewed, and their applications in packaging, sensing, photoelectric catalysis and other fields were also highlighted. Finally, the development opportunities and challenges of bio-based hydrogels were summarized, and the future research directions were prospected.
Stimulus-responsive hydrogels, as a new class of functional polymer materials, can actively sense the difference of the external environment and reflect the change to the outside world by specific ways such as swelling or contraction, and show a great application potential in many fields of life and production. As a renewable natural resources, biomass has been widely applied in the preparation of stimulus-responsive hydrogels in recent years. Particularlly for rapid development of engineering technology and applications, including controllable/active polymerization and click chemistry, dynamic covalent bond, supramolecular self-assembly and super molecular aggregation state regulatory molecules, etc, is able to overcome the instrisic structure defects of biomass macromolecule to a certain extent, and fabricate the stimulus-responsive hydrogels containing unique molecular structure of biomass raw materials, which promoted the development of new green synthesis strategies, multi-functional technology, simple modular synthesis technology, modern biotechnology and other technologies. Based on the stimulus-responsive methods and types of stimulus-responsive hydrogels, this paper assembles six types of hydrogels, including temperature response, acid-base response, light response, electric response, magnetic response and multiple response and highlights the effect of the unique molecular structure of biomass raw materials on the performance of the stimulus-responsive hydrogels. Also, the applications of biomass-based hydrogels with different environmental responses in the fields of drug controlled release, biological tissue engineering, biosensors, adsorption materials, cell culture and antibacterial materials were summarized, and the future development direction of biomass-based hydrogels was prospected.
Based on the freeze-drying process and chemical vapor deposition technology, polyvinyl alcohol(PVA) was compounded with cellulose to enhance the mechanical compressibility and dimensional stability of cellulose(CE) aerogels, followed by the fabrication of highly elastic, hydrophobic, and porous CE/PVA composite aerogels. The effects of PVA content on the mechanical properties of CE/PVA composite aerogels were studied. As the mass fraction of PVA increased, the compressive strength of cellulose aerogels increased. When the amount of PVA was 15% of the mass of cellulose, the compressive strain increased to 66 kPa, which was increased by 6.5 times. Simultaneously, the influences of silane modification on the microstructure, thermal stability, hydrophobicity, specific surface area and physical properties of composite aerogels were explored, and the results showed that S-CE/PVA composite aerogel modified by methyltriethoxysilane(MTES) had a denser lamellar structure, the initial decomposition temperature rose to 314.6℃, the water contact angle was as high as 115°, the specific surface area was 109.42 cm3/g, the density was 0.045 g/cm3, and the porosity was greater than 95%.
Tannic acid(TA) is a kind of multi hydroxyl aromatic biomass. The thermal properties of TA were analyzed by thermogravimetric experiment, the carbonization process of TA was observed by muffle furnace heating experiment, the apparent activation energy was observed by KAS and Ozawa method, and the most probable function was determined by Satava method. Thermogravimetric analysis showed that TA entered the state of rapid weight loss at about 182 ℃; when the temperature reached 800 ℃, the carbon residue of TA in nitrogen atmosphere was 15.29%. In air atmosphere, the carbon residue was 1.97% due to the second rapid weight loss in the temperature range of 436-538 ℃. It was found in the macro carbonization experiment that TA would form an expanded carbon layer when heated. Among them, a hollow carbon layer appeared at 100-200 ℃, and a solid carbon layer was formed at 300-400 ℃, which had obvious expansion, integrity, compactness and good gloss. It had the potential to become a new carbon source in intumescent flame retardants. The results of thermal decomposition kinetics showed that the apparent activation energy of thermal decomposition of TA in nitrogen atmosphere was 494 kJ/mol, lgA was 111.32, and the most probable mechanism function of rapid weight loss stage was G(α)=[-ln(1-α)]1/n, n=0.105 3, and its thermal decomposition mechanism belonged to random nucleation and subsequent nucleation growth reaction.
The consumption of wood adhesive in China is huge. However, the main wood adhesive based on formaldehyde is still prevalent. In recent years, environment friendly adhesives such as non-formaldehyde adhesives and biomass adhesives have developed rapidly. Herein, the recent research and application of wood adhesives including urea-formaldehyde resin adhesives, phenolic resin adhesives, melamine-formaldehyde resin adhesives, protein adhesives, lignin adhesives, starch adhesives, tannins adhesives, isocyanate adhesive, emulsion adhesives and pyrolysis biological oil adhesives were reviewed. The development trend and the research direction of wood adhesives were also prospected.
This paper reviewed the research progress of screening and activity evaluation of terpenoid botanical pesticides in recent 20 years at home and abroad including the perspective of the antifeedant, repellent, poisonous activities and growth regulation of terpene type insecticides, the inhibition of terpene type antibacterial agents, phytopathogens and the activity of terpene type herbicides in the inhibition of seed germination and seedling growth. The investigation and application of agriculture active terpenoid botanical compounds were systematically introduced and summarized. Based on the existing problems in relevant research fields, the development prospects for the screening and application of terpenoid botanical pesticides was forecasted. This review will provide guidance for the synthesis and application of high-active terpenoid botanical pesticides and devote deeply to the exploitation and utilization of terpenoid resources.
Supercapacitors are a new type of green energy storage device with the advantages of fast charging and discharging and long service life. The electrode material is the core component of supercapacitors. The carbon from biomass is considered as a good choice for the preparation of activated carbon because of its wide variety, low price, environmental friendly, porous structure and rich in hetero-atoms, and it is the most popular electrode material for commercial applications. This paper reviewd the effects of pore structure and specific surface area on the performance of electrochemical energy storage of activated carbon, summarized the common pore structures of biomass activated carbon such as tubular, lamellar, honeycomb and network and their electrochemical properties, and analyzed the effects of different biomass components on the performance of activated carbon from three categories: plant-based, animal-based and microbial-based. Finally, the traditional methods of preparing activated carbon and the new preparation methods in recent years were briefly introduced. The problems and challenges of biomass activated carbon were pointed out. Some suggestions were provided to guide the selection of precursors for biomass activated carbon.