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.
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.
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.
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.
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.
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.
Mesoporous activated carbon was prepared from poplar lignin by phosphoric acid activation. The effects of activation temperature(400-900 ℃) and mass ratio of phosphoric acid and lignin(impregnation ratio, 1∶1-4∶1) on the structure of activated carbon LAC-x-y(x represented the impregnation ratio, y represented the activation temperature) were investigated by pore structure, XRD and Raman spectroscopy analysis. The relationship between the electrochemical performance of activated carbon and its structure was investigated by means of electrochemical characterization. Pore structure analysis results showed that increasing the temperature and impregnation ratio was beneficial to the formation of mesopore, but too high temperature would lead to the collapse of pore structure, and too high impregnation ratio would lead to the increase of ash content, which would lead to the degradation of the performance of activated carbon. XRD and Raman spectroscopy results showed that increasing the temperature could improve the degree of graphitization of activated carbon, while increasing the impregnation ratio could decrease the degree of graphitization. Under the activation temperature of 800 ℃ and impregnation ratio of 2∶1, the activated carbon LAC-2-800 had the best performance, with specific surface area of 1 031 m2/g, mesopore ratio of 61% and average pore size of 3.31 nm. As the electrode material of supercapacitor, the specific capacitance reached 165 F/g at 1 A/g current density, and 136 F/g at 10 A/g current density. After 5 000 cycles at 1 A/g current density, the specific capacitance value could keep at 78.1% of the initial value.
In recent years, levulinic acid has been considered as a key biobased platform compound and attracted wide attention, which can be utilized in the synthesis of many high value-added chemicals. Among them, levulinates, as a class of important chemical products, can be used in alternative fuels, edible spices, plasticizers and other fields, especially as alternative fuels, which provides a feasible reference scheme for sustainable development. In this paper, the recent research progress on the catalytic synthesis of levulinates in the field of biomass conversion was reviewed. The reaction performances and related mechanisms were introduced involving in several approaches, such as the esterification of levulinic acid, the alcoholysis of furfuryl alcohol, the conversion of monosaccharides and cellulosic materials, respectively. The synthesis of levulinates was summarized and prospected.
The antibacterial effects of cinnamon essential oil and cinnamaldehyde on bacteria(Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and fungi(Candida albicans) were compared by filter paper method, minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC). The antioxidant activities of cinnamon essential oil and cinnamaldehyde were compared by ABTS+· scavenging ability and ferric reducing antioxidant power(FRAP), as well as their antityrosinase activities were compared. The results showed that the two research subjects showed different sensitivities to the inhibitory effects of the five tested strains, and both had the best inhibitory effect on C. albicans. According to the results of MIC and MBC, cinnamic essential oil and cinnamaldehyde had different inhibitory effects on the tested strains, among which the inhibitory effects of cinnamaldehyde on S. aureus, C. albicans and P. aeruginosa were obviously better than those of cinnamon essential oil. The antioxidant activity of cinnamic essential oil was better than that of cinnamaldehyde. The ABTS+· scavenging rate(94.1%) of 16 g/L cinnamic essential oil was 3 times that of the same concentration of cinnamic aldehyde. The FRAP value(1 502 μmol/L) was 5.8 times that of cinnamaldehyde at the same concentration. Both cinnamon essential oil and cinnamon aldehyde could significantly inhibit tyrosinase activity. The IC50 of cinnamon essential oil to tyrosinase was 4.02 g/L, while the IC50 of cinnamaldehyde to tyrosinase was less than 1.25 g/L.
Corn straw enzymatic hydrolyzed lignin carbon LC1, LC2and LC3 were prepared using purified corn straw enzymatic hydrolyzed lignin as carbon source and carbonized at high temperature under N2 conditions for 1, 2 and 3 h. SEM, TEM and nitrogen adsorption/desorption curve were used to analyze the prepared carbon materials. The results showed that LC1, LC2 and LC3 had microporous, mesoporous and macroporous structures with specific surface areas of 894.75, 1 376.74 and 776.47 m2/g, respectively. The pore volumes of the samples were 0.41, 0.70 and 0.40 cm3/g, respectively. XRD and Raman spectrum showed that the order of the enzymatic hydrolyzed lignin carbon increased with the prolongation of carbonization time. XPS analysis showed that the enzymatic hydrolyzed lignin carbon mainly contained C, O and N(small amount) elements. The electrochemical properties of LC1, LC2 and LC3 were tested using a three-electrode system. The results showed that LC2 had the highest specific capacitance of 222.2 F/g at 0.2 A/g current density, and the specific capacitance of LC2 reached 149 F/g at higher current density of 20 A/g. Further study on its practical application in supercapacitors, the results showed that LC2 assembled symmetric supercapacitor had the largest specific capacitance per electrode and the highest capacitance retention(70.2%). At 1 A/g current density, the LC2 supercapacitor showed good rate performance and electrochemical stability after 5 000 charge-discharge cycles. Moreover, a series battery composed of symmetric LC2 supercapacitor could directly light the LED lamp.
The 2.5 mm bamboo charcoal ultra-thick electrode material was prepared by direct carbonization of bamboo which preserved its straight pore structure. The bamboo charcoal materials Z-700, Z-800, and Z-900 were prepared at 700, 800 and 900 ℃, which were characterized by SEM, XPS, Raman spectra analysis. The results showed that the original bamboo structure was maintained after carbonization. Among them, the carbonized sample Z-900 owned a higher BET specific surface area(SBET) of 483 m2/g, total pore volume(Vtotal) of 0.23 cm3/g, mesoporous pore volume(Vmes) of 0.05 cm3/g, and micropore volume(Vmic) of 0.18 cm3/g. Electrochemical performance tests showed that the specific capacitance of the prepared ultra-thick bamboo charcoal electrode Z-900 was as high as 22.0 F/cm2 in the 6 mol/L KOH electrolyte with the current density of 10 A/m2. When the current density was 200 A/m2, the specific capacitance still reached 14.5 F/cm2 and the capacitance retention rate was 65.9%. The symmetric supercapacitor Z-900//Z-900 assembled with ultra-thick bamboo charcoal electrode Z-900 owned a specific capacitance of 14 F/cm2 at the current density of 10 A/m2, which had a discharge time of 3 500 s, an energy density of 4.9 W·h/m2, and a power density of 5 W/m2. At the current density of 100 A/m2, the coulomb efficiency could reach 99.8% after 10 000 cycles, and the capacitance retention was 88%, which demonstrated that Z-900 had an excellent electrochemical stability.
In order to explore the antioxidant activity of cinnamon polysaccharides, the protein was removed from the water extract of cinnamon(CE)to obtain crude polysaccharides. By using cellulose ion column DE-52 and propylene dextran gel S-300, the cinnamon neutral polysaccharides(CNP) was obtained. The relative molecular mass(Mr) of CNP was determined by gel permeation chromatography(GPC), and the monosaccharide component of CNP were determined by pre-column derivatization high performance liquid chromatography. The connection modes of its monosaccharides were determined by methylation method and nuclear magnetic resonance method. The in vitro chemical model was used to study the scavenging effects of CNP on DPPH· and ABTS+·. The results indicated that the weight average relative molecular mass(Mw) of CNP was 3 630 and the main monosaccharide was glucose. Three kinds of connection modes of monosaccharides were 1, 4, 5-Ac3-2, 3, 6-Me3-Glu, 1, 5-Ac2-2, 3, 4, 6-Me4-Glu, and 1, 5, 6-Ac3-2, 3, 4-Me3-Glu. The determination results of free radicals scavenging by CNP showed that when the mass concentration of CNP was 2 g/L, the DPPH· scavenging rate reached the maximum of 84%, the ABTS+· scavenging rate reached 60%. Although the free radical scavenging rate of CNP was lower than that of Vc, the DPPH· scavenging effect was comparable to that of Vc when the concentration of CNP reached 0.5 g/L. Therefore, the antioxidant activity of cinnamon neutral polysaccharide was good and had good development value.
China was rich in forest resources, and it was an important direction and approach of the development of forestry industry for exploiting the active components of forest resources which were beneficial to human health. With the rapid development of forestry bio-agent industry based on the active components as important material basis in China, targeted molecular imprinting materials have important industrial application value in the accurate separation and high-value processing of forest active components. This article introduced the principle and classification of targeted molecular imprinting technology, as well as the carrier types of several new-style targeted molecularly imprinted adsorption materials in recent years, mainly include graphene, silica, carbon dots and bio-based carriers. It focused on the application status in the separation of flavonoids, polyphenols, alkaloids, organic acids and other forest source active ingredients by targeted molecularly imprinted adsorption materials. Finally, the development of targeted molecular imprinting materials for the separation of active components from forest sources was summarized and prospected, the limitation of targeted molecular imprinting materials and the development trend of targeted molecular imprinting materials in the separation of active components from forest sources were also analyzed.
The hydrolysis of 5-chloromethyl furfural(CMF) in pure water or water/acetone system to 5-hydroxymethyl furfural(HMF) was studied. The effects of hydrolysis reaction conditions(such as solvent system, alkali neutralizer, temperature and CMF addition amount) on the hydrolysis of CMF were investigated, and the kinetics of the hydrolysis reaction was analyzed. The results showed that the water/acetone system is helpful to reduce the side reaction of HMF, and the addition of sodium disulfite(Na2S2O4) could further prevent the generation of humus. The optimal hydrolysis conditions are as follows: 1 g CMF was added with 0.35 g CaCO3 in a mixture of 10 mL water/acetone with volume ratio of 1∶4, and incubated at 353.15 K for 28 min. Under these conditions, the CMF conversion rate was 97%, the yield of HMF was 85%, and the yield of by-product levulinic acid(LA) was 6%. The separation rate of HMF increased from 50% to 86% with the addition of Na2S2O4. The kinetic study results showed that the activation energy of CMF hydrolysis was 12.3 kJ/mol and the hydrolysis rate constant k1=5.56exp(-1.23×104/RT) in water/acetone system.
N and P co-doped carbon aerogels(NPCA) were prepared from cattail inflorescence with NH4H2PO4 as dopant by pretreatment with acidic sodium chlorite, ultrasonic cell fragmentation, freeze-drying and carbonization at high temperature. The surface morphology, pore structure, crystalline structure and surface chemical composition of NPCA were characterized by SEM, N2 adsorption/desorption, XRD and XPS. The effects of doping amounts and carbonization temperatures on the electrochemical properties of NPCA were systematically studied. The results of research showed that NPCA was a three-dimensional network structure that composed of amorphous carbon. The nitrogen element on the surface of NPCA existed in the form of pyridine nitrogen(N-6), pyrrole nitrogen(N-5), graphitization nitrogen(N-Q) and oxidation state of nitrogen(N-X), and the phosphorus element existed in the form of P—O and P—C. The pore structure and surface chemical structure of NPCA were greatly affected by doping amount of NH4H2PO4 and carbonization temperature. The optimum preparation conditions of NPAC were that the mass ratio of cattail-based cellulose to ammonium dihydrogen phosphate was 1∶2 and the carbonization temperature was 800 ℃. The NPAC-2-800 prepared under this condition has rich pore structure and surface functional groups. Furthermore, the specific surface area was 599.88 m2/g, the total pore volume was 0.27 cm3/g, the micropore volume was 0.20 cm3/g, and the average pore size was 3.69 nm, the N and P contents of NPCA were 5.69% and 5.12%, respectively. The electrochemical properties of the NPCA were measured by three electrode system in 6 mol/L KOH solution. The specific capacitance of NPCA-2-800 was 249 F/g at a current density of 1 A/g, which was 133.4% higher than that of the undoped sample(106.7 F/g), and had good rate performance.
The modified coconut shell activated carbons were prepared by loading CuCl2, carbonization and CO2 activation. The Cu-loaded activated carbons were labeled as AC3, AC4, AC5, and AC7 to represent the mass fractions of cupric salt solutions 0.3%, 0.4%, 0.5% and 0.7%, respectively. The Cu-loaded activated carbons were characterized by means of N2 adsorption isotherm, SEM, XRD and XPS. Their dynamic adsorption-desorption performance was measured by the gravimetric method. After modification, the acidic oxygenated groups on the surface of activated carbon decreased. The results showed that cupric salt existed in two forms, i.e., CuO and Cu2O. It was found that the presence of Cu loading led to the decreasing of surface area and pore volume of modified sample, and the increasing of the surface area and proportion of micropore. AC5 showed the largest values of the surface area(733.20 m2/g) and proportion(72.99%) of micropore. Furthermore, AC5 had the optimal equilibrium adsorption capacity(356.40 mg/g) which increased by 33.38% compared to the raw sample, and the optimal equilibrium adsorption time(118.80 min) which increased by 33.38%. Moreover, the adsorption performance of AC5 was better than the activated carbons in the organic gas filter cartridge(3M-3301 CN and 3M-6001 CN). After five cycles of adsorbents regeneration test, 80% of adsorption capability was still able to be reserved. The Cu-loaded activated carbons improved the adsorption performance by transforming the style from physical adsorption to physical-chemical adsorption through complexation of π-bonds in benzene with hollow d-orbitals in Cu2+.
Focusing on alkali-treated bagasse, the effects of solid-liquid mixing methods, addition of three kinds of deep eutectic solvents(DES), feed method of fed-batch feeding, and the addition of xylanase on the enzymatic hydrolysis efficiency at high solid loading were investigated. The results showed that magnetic stirring could accelerate enzymatic hydrolysis speed, but had little effect on the efficiency of enzymatic hydrolysis. Negligible effect on enzymatic hydrolysis was observed by addition of low-concentration DES. A fed-batch with initial substrate loading of 150 g/L was fed at 12 and 36 h, respectively, which resulted in a total solid loading of 350 g/L for enzymatic hydrolysis. After enzymatic hydrolysis for 96 h, the total sugar concentration reached 162.7 g/L with the conversion rates of approximately 51% of both cellulose and hemicellulose. On the basis of fed-batch feeding, 1 000 IU/g hemicellulase was added, and the enzyme cocktail was used for enzymatic hydrolysis for 96 h. The total sugar concentration reached 218.9 g/L, and the conversion rate of cellulose and hemicellulose were 72% and 63%, respectively, which were 40% and 22% higher than those without the addition of hemicellulase.
Epoxy itaconate resin(IE) was synthesized by esterification of itaconic acid(IA) with epoxy resin E51. The IE was then reacted with different half-terminated isocyanates to prepare epoxy itaconate resin modified with isocyanate(DIHIE) in order to improve the UV curing activity. In next, the chemical structure and particle size distribution of IE and DIHIE were characterized by FT-IR, 1H NMR and laser particle sizer. The results showed when the molar ratio of carboxyl group to epoxy group was 2∶[KG-*9]1, the reaction temperature and time was 90 ℃ for 4 h, and the amount of catalyst N, N-dimethylbenzylamine was 3% of the total amount of reactants, while the conversion rate of the IA was about 95%. The half-terminated isocyanate intermediate was synthesized from isophorone diisocyanate(IPDI) and hydroxyethyl methacrylate(HEMA), and then it reacted with IE to obtain IPDIHIE. IPDIHIE was synthesized with acetone as solvent, which was carried out at acetone reflux temperature(56 ℃) for 8 h. The storage stability of the DIHIE dispersion was better when triethanolamine(TEOA) was used as neutralizing agent. The UV curing activity of the resins were improved obviously after being modified by half-terminated isocyanate. The curing time was shortened from 100 s to less than 60 s after modification. The pencil hardness of paint film could reach 4H and the adhesion performance was excellent. Moreover, all of them were about 1 grade.
Blue luminescent carbon quantum dots(B-CQDs) were synthesized by a simple one-step hydrothermal method using lignin and m-phenylenediamine as precursors. Green luminescent carbon quantum dots(G-CQDs) were synthesized by nitric acid oxidation. The optical properties and structures characteristics of these two CQDs were characterized by UV absorption spectroscopy, fluorescence spectroscopy, TEM, FT-IR and XPS. The cytotoxicity and cell imaging properties of G-CQDs were also tested. The results showed that nitric acid played an important role in the synthesis of G-CQDs. The oxidation of nitric acid increased the graphite N content, deepened the graphitization, passivated the surface state, and red-shifted the fluorescence emission wavelength. The results of structural characterization showed that the prepared B-CQDs and G-CQDs were mainly composed of C, N and O elements. All of them had abundant hydrophilic groups such as —OH, —NH, C—O and —COOH on the surface, which were monodisperse in water with the average particle size were 1.3 nm and 2.5 nm, respectively. The results of optical property analysis showed that the excitation wavelengths of B-CQDs and G-CQDs were Ex=392 nm and Ex=446 nm, and the corresponding emission wavelengths were 488 nm and 514 nm, respectively. They exhibited excitation-dependent fluorescence emission behavior and excitation-independent emission behavior, respectively. The results revealed that the possible emission mechanism of G-CQDs belonged to the bandgap fluorescence emissions based on conjugated π-domains. The synthesized G-CQDs with excellent photoluminescence, stable fluorescence and low cytotoxicity could be applied to bioimaging of HeLa cells.
The allyl ether modified lacquer(AGE-L) was successfully prepared by the reaction of lacquer with allyl glycidyl ether(AGE), and subsequently reacted with methacrylic anhydride(MAA) to form a novel lacquer-based monomer with ether bond and ester bond(MAA-AGE-L). Their structures were then characterized by FT-IR, 1H NMR and 13C NMR, and their physical and chemical properties were tested. Additionally, the UV and oxygen(air) curing processes of raw lacquer, AGE-L and MAA-AGE-L were investigated, and the mechanical properties as well as the resistances to chemical media of the cured films were also studied. The results confirmed the successful synthesis of AGE-L and MAA-AGE-L, which were all brownish red liquids. The hydroxyl value of AGE-L was 193 mg/g, the iodine value was 1.89 g/g and the viscosity was 400 mPa·s. The hydroxyl value of MAA-AGE-L was 20 mg/g, the iodine value was 1.39 g/g and the viscosity was 2 000 mPa·s. Compared with lacquer, the surface drying time of MAA-AGE-L was shortened from 2 h to 50 min in presence of the oxygen(air) environment at 30 ℃ with the relative humidity of 80%, and the UV curing surface drying time was shortened from 50 s to 10 s. The pencil hardness of the cured film was H when AGE-L was irradiated by ultraviolet light for 120 s, whereas the pencil hardness of the paint film cured under oxygen(air) for one week was 2H. Moreover, they exhibited good adhesion, flexibility and impact strength. Allyl-modified lacquer films obtained by two curing methods had good water resistance, ethanol resistance, salt water resistance and acid resistance.
In order to enhance the flame retardancy of polysiloxane, a novel flame retardant rosin grafted polysiloxane(RGSO) was synthesized by the amidation reaction of rosin and amino-polysiloxane. The synthesized flame retardant was employed as a part of the soft segment to produce flame-retarding rigid polyurethane foam(RPUF) by "one-pot" process. The flame retardant rigid polyurethane foams(RPUF-1-RPUF-4) were obtained with the rosin amounts of 5, 10, 15 and 20 g. The structure of the flame retardants was characterized by FT-IR and Py-GC/MS. The microstructure, thermal stability, flame retardant property and compressive strength of the RPUFS were analyzed. The results showed that the hydrogenated phenanthrene ring structure of rosin inhibited the gas release of cyclosioxane and promoted the compactness of the silica-rich carbon layer, and invested the materials with excellent flame retardant since it become shielding layer coated on the substrate surface and effectively insulated thermal and oxygen flame retardant. Compared with unmodified RPUF(P-RPUF), the limited oxygen index(LOI) value of the modified sample(RPUF-3) increased by 37.1%, and the peak heat release rate(PHRR) of the modified sample decreased by 44.8%. The fire growth rate(FIGRA) of the modified materials decreased from 10.99 kW/(m2·s) to 4.33 kW/(m2·s), which indicated that the introduction of RGSO could significantly enhance the flame retardant performance of RPUF. Meanwhile, the rigid hydrogenated phenanthrene ring structure of rosin improved the compressive strength of the modified RPUF. The compressive strength of RPUF-4 was 366.7 kPa, which was higher than that of S-RPUF(112.5 kPa).
Molecular imprinted nanospheres(MINs) with high selective adsorption to 10-deacetyl baccatin Ⅲ(10-DAB) was prepared by 10-DAB as template molecule, and 4-vinylpyridine(4-VP) was used as functional monomer. The maximum adsorption capacity reached to 37.42 mg/g. The polymer was characterized by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR) and thermogravimetric(TG) analysis, which indicated that it was successfully synthesized. The adsorption kinetics of 10-DAB-MINs could be well described by the pseudo-second-order model, and R2 was 0.979 5. Meanwhile, the adsorption mechanism conformed to the Langmuir-Freundlich model, and R2 was 0.982 7. The cyclic adsorption results showed that 10-DAB-MINs had better recycling ability than that of the template free molecular imprinted nanaspheres(NINs). Furthermore, the adsorption capacity of 10-DAB-MINs could still reach 28.66 mg/g after recycling for 5 times, which indicated the good stability.
Compounds methyl (Z)-6-((4-(5-(2-(3, 5-bis(trifluoromethyl)phenyl)-2-cyanovinyl)thiophen-2-yl) phen-yl)(4-methoxyphenyl)amino)-7-isopropyl-1, 4a-dimethyl-1, 2, 3, 4, 4a, 9, 10, 10a-octahydrophenanthrene-1-carboxylate(2) and dimethyl 6, 6'-(((1-cyanoethene-1, 2-diyl)bis(thiophene-5, 2-diyl))bis(4, 1-phenylene))bis((4-methoxyphen-yl)azanediyl))(E)-bis(7-isopropyl-1, 4a-dimethyl-1, 2, 3, 4, 4a, 9, 10, 10a-octahydrophenanthrene-1-carboxylate)(3) were obtained simply by mixing 5-(dehydroabietic acid triarylamine)-thiophene-2-carbaldehyde and 3, 5-bis(trifluoromethyl)phenylacetonitrile at room temperature and 100 ℃, respectively. The UV-Vis absorption spectra, fluorescence emission spectra, solvatochromism effect, aggregation-induced emission(AIE) characteristics, thermal stability and electrochemical performance of compounds are studied, and the relationship between their structure and performance is further studied through theoretical calculations. Compared with triarylamine-based acrylonitrile compounds, after introducing the dehydroabietic acid skeleton, the compounds show a larger stokes shift and longer red light emission in the solid state. 2 exhibits AIE characteristics, while 3 does not have AIE characteristics. Both of the two compounds have good thermal stability and morphological stability. 2 and 3 have higher highest occupied molecular orbital(HOMO), lowest unoccupied molecular orbital(LUMO) energy levels and narrow band gap, due to the introduction of dehydroabietic acid skeleton.
By changing the solvent system and pretreatment conditions, a series of studies were carried out on the electricity generation performance of the four types of lignin (enzymatic hydrolysis lignin(EHL), alkaki lignin(AL), sodium ligninsulfonate(SL) and furfural residue(FR))in direct biomass fuel cells. The UV spectrum, FT-IR spectrum and 1H NMR spectrum before and after the reaction of alkali lignin were analyzed. The results showed that the alkali lignin exhibited the best power generation performance, the open circuit voltage(OCV) could reach 392.7 mV, and the peak power density(PPD) was 0.198 W/m2. And lignin had the best power generation performance in NaOH solution. Water bath heating pretreatment could improve the power generation performance of lignin. The higher the temperature and the longer the treatment time, the better the power generation performance of the lignin would be. When lignin was irradiated with ultraviolet light, the electricity production performance increased first and then decreased with the passage of time. The electricity production performance was the best when it was treated for 24 hours. The OCV could be increased to 431.2 mV, and PPD was increased to 0.371 W/m2. After the oxidation reaction in the fuel cell, the benzene ring structure of lignin had been destroyed to a certain extent, and the hydroxyl group on the benzene ring had been oxidized to a carbonyl structure. The UV absorption peak of alkali lignin produced red-shift and color enhancement effects. And in the FT-IR spectrum, the carbonyl absorption peak was enhanced. Especially, the signals of aromatic protons, phenolic hydroxyl groups and aliphatic hydroxyl groups were weakened in 1H NMR spectrum.
The paper presented a method for the pretreatment of bamboo wood with AlCl3 assisted eutectic solvent(DES). The DES was synthesized using choline chloride and AlCl3 as the hydrogen acceptors, and guaiacol used as the hydrogen donors. The effects of AlCl3 dosage in DES on the chemical composition and subsequent enzymatic hydrolysis efficiency of the pretreated bamboo were investigated. The results showed that with the increase of AlCl3 dosage, the contents of xylan and lignin decreased gradually with the content of glucan increased in pretreated bamboo, which significantly improved its enzymatic hydrolysis efficiency. Under optimal conditions(the amount of choline chloride, guaiacol and AlCl3 was 25∶50∶1). The conversion rate was 42.84%, the recovery of glucan and xylan were 95.95% and 12.84%, respectively, with 74.88% lignin removal. Compared with the DES treatment without the addition of AlCl3, glucan enzymatic hydrolysis with AlCl3-assisted DES treatment increased from 11.16% to 96.20%. The results demonstrated that AlCl3 could effectively promote the dissolution of xylan and lignin. The pretreated materials were characterized by XRD, SEM, and FT-IR. XRD analysis showed that with the increase of AlCl3 dosage, the crystallinity of the pretreated materials increased gradually, mainly due to the gradual removal of lignin and xylan components, while the cellulose components were not significantly damaged. SEM analysis showed that after pretreatment, the pretreated materials appeared obviously fragmentation and agglomeration. With the increase of AlCl3 dosage, the bamboo components were gradually dissolved and destroyed. The FT-IR analysis results also proved that the increase of cellulose content in the pretreated materials accompanied by the gradual decrease of xylan and lignin.
Lignin-based phenolic resin(LPF)with high phenol substitution rate(≥70%) were synthesized based on alkali lignin(UL)from black liquor of kraft pulping of spruce, or based on demethylated lignin(DUL) and hydroxymethylated lignin(HUL) obtained from the modification of UL. The effects of the hydroxyl content of three types of lignin on the adhesive strength and free formaldehyde content of LPF adhesives were compared and analyzed in this paper. The results of structure analysis of lignin showed that the hydroxyl ratios of DUL and HUL increased by 26.41% and 72.35%, respectively, while compared to raw UL. UL, DUL and HUL were separately used to replace phenol for the preparation of LPF that were applied in the bonding experiment of poplar veneer. The experimental results showed that demethylation of UL could further improve the heat-resistant water-based bonding strength((σHWT). At 30% lignin substitution rate, DUL showed the largest σHWT of 1.09 MPa, which was 39.39% higher than PF(0.78 MPa). The replacement rate of lignin increased from 30% to 70%. Meanwhile, the content of free formaldehyde in plywood decreased from 0.33 mg/L to 0.29 mg/L, which was still less than the requirement of national standard GB 9846.2—2004(< 0.5 mg/L). The bonding strength of LPF prepared from HUL was significantly improved after modification of UL by hydroxymethylation. At 30% lignin replacement rate, the dry bonding strength(σdry) and wet bonding strength(σWST) were 2.55 MPa and 1.99 MPa which increased by 79.02% and 135.31% respectively, while compared those with PF(1.43 MPa and 0.84 MPa).
Cellulose acetate nanofibers(CANFs)were prepared by electrospinning cellulose acetate(CA), followed by deacetylation to obtain cellulose nanofibers(CNFs). Subsequentially, in-situ polymerization of polypyrrole was perform to fabricate the conductive composite nanofibers(CNFs-PPy), which was combined with cellulose paper as a flexible substrate for assembling a flexible pressure sensor. The materials were characterized by FT-IR, XRD and SEM, and the mechanical and sensing performance of the devices were analyzed using a universal material testing machine and an electrochemical workstation. The results showed that polypyrrole was successfully coated on the surface of cellulose nanofibers, and the nitrogen content of composite nanofiber was 24.8%. The current-voltage curves of the sensor maintained a good linear relationship under 1-15 kPa pressure load, and the relative current change rate increased with increasing pressure. The sensitivity values of the sensor were up to 1.77 kPa-1 in the range of low pressure(0-0.99 kPa), 0.43 kPa-1 in the range of medium pressure(1.00-8.33 kPa) and 0.22 kPa-1 in high pressure(8.53-15 kPa), respectively. The sensor had excellent signal reliability and stability, i.e., the sensing signal remained stable after 3 000 cycles of loading. The sensor could realize the real-time monitoring of external pressure changes such as finger touch, which provided a new insights into the development of green electronics.
Anethole-based carboxylic acid, which maintained the phenylpropanoid C6-C3 active structural unit in anethole, was prepared by Perkin condensation reaction of propionic anhydride with anisaldehyde obtained by the oxidation of anethole. Then, nineteen anethole-based diacylhydrazine compounds(6a-6s) were synthesized via esterification, hydrazinolysis, and N-acylation reactions. All the target compounds were characterized by FT-IR, 1H NMR, 13C NMR, and ESI-MS. Their antifungal activity against eight tested plant pathogens was also evaluated. The results showed that, the target compounds showed certain antifungal activity against the eight tested plant pathogens, at the mass concentration of 50 mg/L. Among them, compounds 6a(R=H), 6f(R=m-Cl), 6o(R=p-I), 6p(R=p-OH), and 6q(R=p-t-Bu) had inhibition rates of 94.8%, 96.1%, 91.7%, 96.1%, and 91.7% against Physalospora piricola(all in A-class activity level), which were much better than that of the positive control chlorothalonil. Compounds 6f(R=m-Cl) and 6p(R=p-OH) were worthy of further investigation.
Acetic acid lignin(AAL) was fractionated by dissolution in aqueous solution of acetic acid with various mass fraction. Four fractions with different relative molecular weight, which were chosen from the fractionation products, were sulfomethylated to obtain products with different relative molecular weight and sulfonic group content. The sulfomethylated lignin(SML) was added into myclobutanil as a pesticide dispersant to get a 40% myclobutanil wettable powder(WP). The influence of relative molecular weight and sulfonic group content on the application performance of 40% myclobutanil wettable powder was investigated. The results indicated that the suspension rate of myclobutanil increased from 72.68% to 83.69% and the wetting time increased from 45 s to 62 s when the average molecular weight increased from 5 768 to 13 964. The suspension rate of myclobutanil increased from 73.56% to 84.86% and the wetting time decreased from 72 s to 57 s when the sulfonic group increased from 0.51 mmol/g to 1.78 mmol/g. The average particle size of the dispersed phase of a 40% myclobutanil WP decreased when the relative molecular weight and sulfonic group content increased. However, too high relative molecular weight resulted in a decrease of the suspension rate of myclobutanil.
Gum rosin derived methacrylate(GRGMA) was firstly synthesized by the esterification reaction between gum rosin(GR) and glycidyl methacrylate(GMA). Subsequently, atom transfer radical polymerization(ATRP) was applied to fabricate ethyl cellulose-gum rosin-fatty acid derived co-polymer(EC-R-LMA). The structure and properties of GRGMA and EC-R-LMA were then characterized by FT-IR, 1H NMR, DSC, TG/DTG, universal tensile machine and contact angle measurement. It was found that the monomer conversion was higher than 90%. With the increase of the molar ratio of GRGMA from 10% to 70%, the Tg of EC-R-LMA increased from -61.3 ℃ to 62.58 ℃. Particularly, when the molar ratio of GRGMA increased from 30% to 35%, the tensile strength at break increased from 0.41 MPa to 0.50 MPa, whereas the tensile strength at break of the cross-linking polymer(BMI-EC-R-LMA) increased to 1.04 and 1.27 MPa respectively after cross-linking. It was also observed that when the molar ratio of GRGMA and LMA was set to 1∶9 and 2∶8, the Tg of EC-R-LMAs were -61.3 ℃ and -52.9 ℃, respectively, which could be used as a pressure-sensitive adhesive(PSA). Notably, GRGMA acted as a new type of hard monomer for the PSA rather than as a tackifying resin. While the molar content of GRGMA increased from 10% to 20%, the 180° peel strength of PSA increased from 0.56 N/cm to 1.08 N/cm, and the shear resistance property increased from 2 h to more than 72 h.