An anti-freezing hydrogel electrolyte(SPI-PVA-PAAm/LiCl) was synthesized, in which soybean protein isolates (SPI), ployvinyl alcohol(PVA) and acrylamide(AAm) were used as raw materials, ammonium persulfate(APS) was used as the initiator, N, N'-methylenebisacrylamide(MBAA) was used as the covalent crosslinker, LiCl was used as the electrolyte salt, and N, N, N', N'-tetramethylethylenediamine(TEMED) was used as the accelerator. Under low temperature conditions, the mechanical properties of the hydrogel electrolyte were analyzed, and the electrochemical properties of the solid-state supercapacitor based on this hydrogel electrolyte were investigated. The results showed that the hydrogel electrolyte had excellent anti-freezing propertity, because a certain molar concentration of LiCl reduced the freezing point of pure water in the hydrogel electrolyte and inhibited the crystallization behavior of water molecules. When the environmental temperature was reduced from 25℃ to -20℃, the hydrogel electrolyte still showed good mechanical properties and ionic conductivity. With the increase of the amount of LiCl, the compression performance of the hydrogel electrolyte firstly increased and then decreased, and the ionic conductivity increased. After 10 cycles of 80% compression strain, the stress retention rate, plastic deformation rate and energy loss coefficient of the hydrogel electrolyte with LiCl concentration of 5 mol/L(S-Li-5) were more than 100%, less than 25% and 0.33, respectively. The hydrogel electrolyte with LiCl concentration of 15 mol/L(S-Li-15) and CNTs were used to assemble the solid supercapacitor whose electrochemical performance was evaluated. When the ambient temperature was reduced from 25℃ to -20℃, the specific capacitance of assembled supercapacitor calculated by GCD curve could be maintained above 80%, and 0-70% compression strain could be withstood without damage, and the supercapacitor could still work normally; In addition, when the current density was 8.12 A/g, the capacitance retention rate of the device was higher than 91% after 1 000 cycles at -20℃.
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.
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.
Desirable pine resources are the basis for the sustainable, high value-added and fine chemical utilization of pine oleoresin. According to the chemical composition and structural characteristics of pine oleoresin, combined with the analysis of the current situation of pine oleoresin resources as well as their deep processing and utilization industries, the demand for individuation pine resources is discussed from the perspective of fine utilization. By the perspectives of production, processing, utilization and benefits, intensive high-quality pine oleoresin resources are needed, which have strong oleoresin exudation, long-lasting resinosis, good quality, and easy processability. And by the perspective of deep processing and utilization, individuation oleoresin resources are needed further, which have higher quality, more useful, more balanced or more outstanding specific components. To research and breed individuation pine resources such as pimaric-type rosin, isopimaric-type rosin, mercusic-type rosin, α-pinene-type turpentine, β-pinene-type turpentine, 3-carene-type turpentine, β-phellandrene-type turpentine and longifolene-type heavy turpentine, are scientifically important and applicably valuable for the fine chemical utilization, high value-added deep processing of rosin and turpentine. It is recommended to focus on the main oleoresin-tapping pine species such as P. massoniana, P. kesiya var. langbianensis, P. elliottii, P. elliottii×P. caribaea, P. latteri Mason, etc., and carry out more integrative and interdisciplinary researches on oleoresin chemistry, fine chemicals, genomics, metabolomics, genetic breeding, resource cultivation, and chemical engineering of forest products.
Cellulose and chitosan are the two most abundant natural biomass polymers on the earth. The novel, green and functional composite nanofibers derived from cellulose and chitosan were expected to be obtained by electrospinning, which can further expand their applications. The selection and development of the optimum solvent system is a crucial prerequisite and guarantee for the preparation of high-quality nanofibers by electrospinning. The characteristics, dissolution effects, mechanisms and spinning performance of the main solvent systems(including organic solvents, aqueous solvents and ionic liquid solvents) for electrospun cellulose, chitosan single and composite nanofibers were reviewed, which could provide a theoretical reference for the high value-added nano-utilization of cellulose and chitosan as well as the development of functional biocomposite nanofibers.
In order to promote the development of biomass gasification technology and the utilization of gasification products, the development and industrial status of biomass gasification technology, gasifier type and its development status at home and abroad were mainly introduced, and the advantages and disadvantages of biomass gasification technology were analyzed. At the same time, it is also found that China's biomass resources had great potential and biomass energy had the excellent characteristics of renewability, such as renewable, less pollution, large reserves, wide distribution, zero carbon emissions and so on. However, it was difficult to internationalize because of a series of problems such as imperfect of collection-storage-transportation system, shortage of capital chain and more by-products. It was further prospected that biomass gasification in China should not only take a basic research, but also consider the overall demand of biomass gasification technology and the competition with other technologies as the future development direction and important key point. This paper was expected to lay a solid foundation for the further development of biomass gasification technology and the high-value utilization of gasification products.
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.
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%.
In this article, the research progress of electrochemical technology of lignin depolymerization recently, including micro electrochemical expression of lignin depolymerization, types of catalysts, electrode materials and electrode mechanism of electrochemical reactor and other strategies, were reviewed. The frontier research of lignin depolymerization by electrochemical technology combined with ionic liquid catalysis system, biological enzyme catalysis system and photocatalysis technology were analyzed. The influences of electrode material and current density on electrocatalytic efficiency were summarized, and the challenges as well as the opportunities of the application of electrochemical technology were presented.
A choline chloride-urea(molar ratio of 1:2) based deep eutectic solvent(DES) system was used as a non-hydrolytic pretreatment media to prepare the cellulose nanofibrils(CNF) from bleached kraft poplar pulp by using microfluidizer. The properties of CNF were characterized by elemental analysis, scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), thermogravimetric analysis and X-ray diffraction analysis. Furthermore, the polymerization degree(DP) of CNF and the energy consumption were calculated. The results showed that DES pretreatment could promote the swelling of pulp fibers, which was beneficial to fibrillation during the microfluidization process. The microfluidization treatment, was performed 15 times. It was found that compared with the energy consumption(4.35×107 kW·h/t) of raw materials without DES pretreatment, the energy consumption(2.44×107 kW·h/t) of raw materials with DES pretreatment decreased by 43.91%. whereas the crystallinity indexes(ICr) of CNF prepared before and after pretreatment were 54% and 44%, respectively. However, DES pretreatment had no obvious effect on the polymerization degree of fiber raw materials. DES pretreatment also reduced the thermal stability of CNF. The increase of homogenization times could promote the fibrillation of fibers, and reduce the crystallinity and polymerization degree of cellulose at the same time. FT-IR analysis showed that choline cations interacted with anionic groups of cellulose fibers through static electricity during DES pretreatment. Elemental analysis showed that nitrogen-containing residues remained in CNFs.
Nanocellulose is a kind of nano-sized cellulose extracted from natural cellulose. It not only has the basic characteristics of cellulose, but also has large specific surface area, unique strength and optical properties originated from nano-size. However, the presence of free hydroxyl groups in cellulose is hydrophilic, which reduces the stiffness of nanocellulose materials in humid environments and limits its application fields. Therefore, hydrophobic modification of nanocellulose can expand its scope of application. This article reviewed the methods of hydrophobic modification of nanocellulose in recent years, including physical adsorption modification, esterification/acetylation modification, graft copolymerization, silane coupling agent modification, etc., and summarized the research results of the above methods, as well as the advantages and disadvantages. And the future development direction was prospected in order to provide reference for hydrophobic modification research.
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.
This article reviews the recent research progress of preparation of 2, 5-furandiformaldehyde(DFF) by the oxidation of 5-hydroxymethylfurfural(HMF) with transition metal-based catalysts. The application of manganese-based, copper-based, vanadium-based, iron/cobalt-based and other catalytic systems in the preparation of DFF by HMF oxidation is mainly introduced. The effects of different reaction conditions on the catalytic performance of the catalyst are analyzed in detail, the reaction mechanism of different catalysts is explained, and the advantages and disadvantages of different catalysts are summarized. In addition, based on the analysis of the existed problems in the current catalyst catalysis process, the development prospects of the transition metal-based catalysts catalyzed by HMF oxidation to prepare DFF are also prospected.
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 vapor-liquid equilibrium data of pine resin system with the content of rosin among 0 to 70% as well as the effect of desorption of superior oil of turpentine(95.85% α-pinene) and medium oil of turpentine(36.00%α-pinene) from the distillation of oleoresin were determined by modified Ellis equilibrium cell and gas chromatography at the temperature of 428.15-488.15 K and atmospheric pressure. The results showed that the phase equilibrium temperature increased by the content increasing of rosin in oleoresin, which indicated that the lower concentration of turpentine in oleoresin was, the higher distillation temperature of oleoresin was, that was to say, the turpentine components were difficult to be desorbed from rosin. However, the content of rosin had little influence on vapor-liquid equilibrium data of distillate composition in turpentine. According to the results of vapor-liquid equilibrium properties and the effect of desorption, circulating N2 or CO2 distillation method the was designed to modify the process of pine gum distillation. Compared with traditional overheated steam method, the annual consume of standard coal, cooling water and greenhouse gas CO2 by circulating N2 or CO2 method based on 10 000 tons of rosin were decreased by 567.4-694.0 tons, 1.329×105-1.624×105 m3 and 2 080-2 545 tons, respectively. The production processes of separator for oil from water and filter for salts were not required. Water was not contaminated in products of rosin and turpentine. There was no emission of waste gas, waste water with turpentine and waste salts. The loss of turpentine and the emissions of waste salt were decreased by 13.52-29.72 tons and 60 tons annually. The obtained rosin and turpentine products met the national standard requirements.
Miscanthus-based lignocellulosic nanofibrils(LCNF) was produced by using citric acid pretreatment followed by the high-pressure homogenization with using miscanthus straw fiber as raw material. LCNF was cross-linked with 4, 4'-diphenyl-methane-diisocyanant(MDI) by using triethylamine as catalyst to obtain aerogel with high oil absorption capacity. The properties of aerogels were characterized by cold field emission scanning electron microscope, Fourier transform infrared spectrometer(FT-IR), thermogravimetric analyzer, and optical contact angle analyzer, and the oil absorption performance of aerogel was determined by gravimetric method. The results showed that the modified LCNF aerogel exhibited obvious multi-level rough micro/nanostructure with good thermal stability, hydrophobicity, and oil absorption capacity; the maximum weight loss temperature and water contact angle were 353.6℃ and 152.2°, respectively. FT-IR showed that cross-linking reaction was occurred between the hydroxylgroup on LCNF and the isocyanate group of MDI. When the mass ratio of LCNF to MDI was 1:4, the water contact angle of themodified aerogel was 138.1°, and the oil absorption performance was the bestwith chloroform absorption capacity of 41.6 g/g.
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.
Nitrogen-doped activated carbon was fabricated by one-step pyrolysis with Chinese fir sawdust as raw material, melamine solid waste(oxhydryl and amino triazine, OAT) as nitrogen-rich source, alkali/urea system as solvent. The effects of activation temperatures and melamine solid waste dosage on adsorption performance and electrochemistry performance of activated carbon were investigated. X-ray photoelectron spectroscopy(XPS) and specific surface area analyzer were used to study the surface structure and pore structure of the material. Cyclicvoltammetry(CV) curves, galvanostatical charge/discharge(GCD) and electrochemical impedance spectroscopy(EIS) were used to test the electrochemical performance of samples. The results showed that with the increase of melamine solid waste content, the yield and adsorption performance of activated carbon samples increased first and then decreased; the addition of melamine solid waste was beneficial to increase the yield, nitrogen content, adsorption performance and electrochemical performance of nitrogen-doped activated carbon. The specific surface area and pore structure of carbon materials affected the electrochemical performance of activated carbon samples. When the activation temperature was 900 ℃ and the melamine solid waste content was 15%, the yield of nitrogen-doped activated carbon was 34.2%, the iodine adsorption value was 1 116 mg/g, and the methylene blue adsorption value was 165 mg/g, specific surface area was 1 324 m2/g, nitrogen content was 3.5%. In the 6 mol/L KOH electrolyte, the specific capacitance could reach 193 F/g when the current density was 1 A/g.
As an important part of renewable energy, biomass resources have a wide range of sources. However, large-scale application is limited due to the properties of biomass, such as dispersion, low bulk density, low calorific value, and high hygroscopicity. Solid briquette fuel is one of the important ways to promote the large-scale application of biomass, which can replace coal and other fossil fuels. As one of the pretreatment methods to improve the physical and chemical properties of briquette fuel, torrefaction can improve the hydrophobicity of biomass briquette fuel and optimize its physical and chemical properties, which is a research hot topic at home and abroad. In this paper, the factors of torrefaction pretreatment and characteristics of torrefaction products were summarized, the factors and the lignin bonding mechanism of the pelletization process were analyzed, the influence of torrefaction pretreatment on the preparation of clean solid fuel was described, and the application of torrefaction and upgrading solid fuel process was prospected. This paper provides reference for promoting the development and application of biomass briquette fuel in China.
As a medical plant with a long history, the Usnea species of lichen are widely distributed in China. However, the research about its chemical composition and activity is rare, delayed, and the basic data accumulation is weak, which restricts its further development and utilization.The primary metabolites polysaccharide(lichenan, isolichenan, galactomannan, and heteropo-lysaccharide) and fatty acids, and secondary metabolites(single benzene ring derivatives, depsides, depsidones, and benzofuran) of the Usnea species of lichen are reviewed in this article.The research progress of the bioactivity of lichen polysaccharide and lichen acid are introduced. Lichen polysaccharides have functions of antioxidation and antitumor; and lichen acids have functions of insecticidal, antibacterial, anticancer, antitumor, antioxidation, antivirus, antiinflammatory, liver-protecting, detoxication, and enzyme inhibition.
Dehydroabietic acid(DA) reacted with 3-glycidyloxypropyltriethoxysilane(GTS) to synthesize dehydroabietic acid-based cross-linking agent(DAG), and then DAG was combined with TiO2, catalyst dibutyltin dilaurate, and hydroxyl polysiloxane(PDMS) to fabricate the TiO2 modified dehydroabietic acid cross-linked the room temperature vulcanized silicone rubber(TiO2-DAG/RTVSR). The microscopic morphology, mechanical properties, thermal stability, and hydrophobicity of the samples were investigated. The results showed that DAG and TiO2 were uniformly dispersed in the dehydroabietic acid cross-linked silicone rubber. Compared with DAG/RTVSR-3 obtained by only adding DAG, when the addition of TiO2 was 7%, the tensile strength of the obtained TiO2-DAG/RTVSR-4 increased from 0.65 MPa to 0.98 MPa which increased by 50.8%, and the elongation at break increased from 250% to 317%.The 5% mass loss temperature of silicone rubber increased from 324.5℃ to 338.8℃ as the addition of TiO2 increased from 0% to 7%; and the swelling degree decreased, which indirectly reflected the increase in the degree of cross-linking.The contact angle gradually decreased with the increasing of TiO2 amount. These results indicated that the synergistic effect of dehydroabietic acid with rigid structure and TiO2 into the molecular chain of silicone rubber could effectively enhance the mechanical properties and thermal stability of room temperature vulcanized silicone rubber.In summary, silicone rubber with 7% TiO2 had the best performance.
Furfural residue is the biomass waste in the process of furfural industrial production. In this paper, the sources and composition characteristics of furfural residue are firstly introduced. On this basis, the researches of furfural residue in the fields of biomass energy, composite materials, fine chemicals and agricultural supplies are reviewed, and the research progress in various application fields is analyzed and summarized. Finally, according to the characteristics of furfural residue, the existing problems and challenges in the application of furfural residue are pointed out and the high-value utilization of furfural residue are also prospected.
Pretreatment was a key step in sugar platform -based biomass refinery using lignocellulosic biomass as raw material. In this paper, the advantages and disadvantages of the commonly used methods such as dilute acid/alkali, steam explosion, liquid hot water, microwave, subcritical CO2, ionic liquids, deep-eutectic solvents, organosolv, milling/grinding, and biological, and the research progress of subsequent enzymatic hydrolysis and fermentation were reviewed. Furthermore, the application of the co-production of ethanol and platform chemicals in the pretreatment of biomass feedstock at home and abroad based on Aspen Plus and techno-economic analysis were introduced. Finally, the drawbacks of Aspen Plus in biomass pretreatment for ethanol production were summarized and the further research directions were proposed.
In this work, the effects of sodium chlorite(SC) and sodium hydroxide(SH) pretreatments on the chemical composition of poplar were investigated. The preparation of xylooligosaccharides(XOS) and monosaccharides by enzymatic hydrolysis was discussed. The results showed that poplar lignin could be selectively removed by SC pretreatment. After 6% SC pretreatment at 70℃ for 3 h, the removal of lignin reached 65.8%, whereas 90.7% glucan and 92.4% xylan were retained. The data of X-ray diffraction and X-ray photoelectron spectroscopy indicated that SC pretreatment removed the total lignin in poplar and the surface lignin on poplar, and increased the crystallinity and accessibility of the substrate. After the pretreatment with 6% SC at 70℃ and 1% SH at 50℃, the contents of glucan, xylan, and lignin in the pretreated poplar were 67.8%, 21.5%, and 2.9%, respectively. The highest XOS yield of 47.2% from the SC-SH-pretreated poplar by xylanase hydrolysis was obtained, and the XOS preparation was composed of 98% xylobiose. Compared with the poplar treated by 6% SC at 70℃ for 3 h, SH pretreatment increased the yield of XOS by 7.1 times. After the hydrolysis by xylanase, the glucose yield of two-step pretreated poplar residue was 90.2% with a cellulase lading of 30 mg/g dry matter. Finally, 52.5 g XOS, 317.6 g glucose and 49.9 g xylose were obtained from 1 kg raw poplar. The results of this work provided a theoretical guidance for the preparation of XOS and monosaccharides from poplar under mild conditions.
Activated carbon was prepared by phosphoric acid activation method with corn stalks as raw materials. The carbon quantum dots(CQDs) were prepared by hydrothermal synthesis with the activated carbon as the carbon source. The CQDs/TiO2 composite photocatalyst was prepared by CQDs and TiO2 composite. CQDs were characterized by FT-IR, XPS, TEM, XRD andRaman spectroscopy, confirming that CQDs mainly contained C and O elements, and they existed in a combination of C-C/C＝C, C-O and C＝O. CQDs were mainly nano spherical particles with an average particle size of 3.1 nm, which were composed of graphitized carbon core and functional groups. Moreover, the fluorescence performance of CQDs showed that the optimal excitation wavelength was 315 nm and the emission wavelength was 435 nm with blue fluorescence emission. The successful preparation of CQDs/TiO2 photocatalyst was confirmed by TEM and XPS, and the composite of CQDs and TiO2 was connected by Ti-O-C. Through the comparative analysis of catalytic degradation performance of CQDs/TiO2 and TiO2 under UV light (365 nm), xenon lamp simulated sunlight and outdoor sunlight, the results showed that the catalytic performance of CQDs/TiO2 was lower than pure TiO2 under UV light. The catalytic degradation performance of CQDs/TiO2 under visible light(simulated sunlight and outdoor sunlight) was superior to pure TiO2, and the highest degradation rate was 99.51% after outdoor sunlight irradiation for 105 min, basically degraded completely.
Hydrodeoxygenation(HDO) process of phenolic compound is an important process for upgrading and refining bio-oil to high value-added chemicals and high-quality liquid fuel, in which the catalyst plays a vital role. Research on the catalytic process of hydrodeoxygenation of bio-oil model compound phenols has important reference significance for bio-oil upgrading and refining. Phenolic compound hydrodeoxygenation catalysts mainly include precious metal catalysts, non-precious metal catalysts and bimetallic catalysts. This paper summarized the advantages and disadvantages of various catalysts, and briefly described the mechanism of various catalysts in the process of phenol hydrodeoxygenation. And the catalyst was evaluated for substrate conversion, product selectivity, and catalyst stability.
Hollow mesoporous silica microspheres SiO2-1 and SiO2-2 were prepared by sol-gel and hydrothermal synthesis using dichloride-N, N'-bis (3-hydrorosin loxy-2-hydroxypropyl) tetramethylenediamine (DHRT) as template agent and ethyl orthosilicate as silicon source.SEM, TEM, FT-IR, XRD and nitrogen adsorption-desorption were used to characterize SiO2-1 and SiO2-2.The results showed that silicon dioxide microspheres with amorphous structure were successfully prepared by both methods; the agglomeration phenomenon between silica particles gradually disappeared with the increase of the amount of template agent (0.1-1 g); SiO2-1 was mainly loose microsphere with patterns, and SiO2-2 was hollow microsphere with the wall thickness of 80-85 nm.The average particle size distributions of SiO2-1 and SiO2-2 prepared with different template dosages (0.3-1 g) were 0.22-0.33 μm and 0.34-0.41 μm, respectively.The morphology and particle size of SiO2-1-0.7 and SiO2-2-0.7 prepared by two methods exhibited good morphology and low particle size, with specific surface area of 561.52 and 463.41 m2/g, cumulative pore volume of 0.35 and 0.42 m3/g, and average pore size of 2.56 and 3.66 nm, respectively.Zeta potential analysis showed that the formation of SiO2 hollow mesoporous structure was mainly caused by the cooperative self-assembly process between the oligomer obtained by hydrolyzing polycondensation of ethyl orthosilicate and the template agent.
In order to further broaden the application of Cinnamomum cassia leaves essential oil in food, feed and other fields, C. cassia leaves essential oil/β-cyclodextrin microcapsules were prepared by co-precipitation method with β-cyclodextrin as the wall material and C. cassia essential oil as the core material. The preparation conditions of microcapsules were optimized by orthogonal experimental design. Essential oil/β-cyclodextrin microcapsules were characterized by using gas chromatography-mass spectrometry(GC-MS) and Fourier transform infrared spectroscopy(FT-IR).The results showed that the suitable preparation conditions of microcapsules were wall-core ratio 6:1, temperature 50℃, time 4 h and stirring speed 1 000 r/min. The encapsulation efficiency of C. cassia essential oil of the obtained microcapsule was 74.17%. The GC-MS analysis showed that the main compositions of C. cassia essential oil were trans-cinnamaldehyde(81.39%), followed by o-methoxycinnamaldehyde(7.61%) and the main compositions of C. cassia essential oil in the microcapsule were also trans-cinnamaldehyde(78.68%) and o-methoxycinnamaldehyde(9.34%). FT-IR analysis showed that C. cassia leaves essential oil and β-cyclodextrin formed good inclusion complex. C. cassia leaves essential oil/β-cyclodextrin microcapsules had good thermal stability and slow-release properties.
Rosin is an important biomass resource in China, and its main component resin acid contains tricyclophenylene skeleton strong hydrophobic rigid group and carboxyl weak hydrophilic group. Rosin can be used to disperse inorganic nano materials and reduce the aggregation of inorganic nano materials. The surfactant with excellent hydrophilic and lipophilic properties can be obtained by chemical modification of acid double bond and carboxyl group of rosin resin, which has better "fusion" with inorganic materials. Rosin based surfactant can be used as template and dispersing agent to prepare a variety of inorganic functional materials. The rosin based small molecule/inorganic hybrid materials and rosin modified polymer/inorganic hybrid materials can be obtained by designing functional rosin derivatives to bond with inorganic materials. Based on the structural characteristics and chemical properties of rosin and its derivatives, the application of rosin and its derivatives in inorganic functional materials was reviewed, and the application prospect of rosin derivatives in the development of inorganic functional materials was prospected.
Nowadays, the application of hydrotropes is one of the research hotspots in the field of biorefinery. Hydrotrope can effectively separate the lignocellulosic components to realize the high value-added utilization of the products, such as producting biofuels, biochemicals, and biomaterials. In this work, we provided a review of the applications of hydrotropes for fractination of cellulose, hemicelluloses and lignin, and producting bioethanol, cellulose nanocrystals(CNCs) and nano lignin etc..