As a green bio-based platform chemical, 2, 5-furan dicarboxylic acid(FDCA) was widely used in polyester, plasticizer, fire protection, medicine, etc. At present, according to the distinction of raw materials for the synthesis of FDCA, the synthetic routes of FDCA could be divided into 5-hydroxymethylfurfural(HMF) route, furoic acid route and other raw material routes. Among them, furfural acid could be prepared from the oxidation of bulk bio-based chemical furfural, and the industrial production of furfural made the preparation of FDCA from furfural acid had the potential advantages of green and economical. Based on this, this paper reviews the research status of four methods for preparing FDCA from furoic acid, including: disproportionation, carbonylation, carboxylation and biocatalysis methods. The paper also summarizes a comparative analysis of the advantages and disadvantages of each method and highlights the progress made in their respective research fields. A comparative analysis indicates that the C-H carboxylation method is a gentle and environmentally friendly process, demonstrating significant potential for large-scale production.
In this work, furfural-based monomer tetrahydrofurfuryl methacrylate(THFMA), disproportionated rosin-based monomer(DRM), and oil-based monomer lauryl methacrylate(LMA) were used as raw materials to prepare a series of bio-based pressure-sensitive adhesives(PSA) based on THFMA/DRM/LMA by solution polymerization method. The effects of hard monomer and soft monomer composition ratio and the monomer molecular structure on the performance of PSA were investigated in detail. The results showed that the adhesion increased from 0.48 to 72 h with the increase of hard monomer THFMA in PSA from 10% to 50%. When the content of THFMA was 30%, the comprehensive performance of PSA was the best. The tack of THFMA30-LMA was 2.28 N, the 180° peel strength was 143.6 N/m, and the shear resistance reached 21.25 h. In addition, compared with THFMA, using DRM as hard monomer could enhance the mechanical properties of PSA and improve the thermal stability of PSA.
Porous graphitic carbon nitride(mpg-CN) material with large surface area(126.6 m2/g) was successfully prepared by removing silica from a graphitic carbon nitride(g-C3N4)/silica composite, where the latter was synthesized using urea and tetraethyl orthosilicate(TEOS) as precursors through thermal polycondensation. Nitrogen adsorption-desorption isotherm, SEM, TEM, XRD, ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), photoluminescence spectroscopy(PL) and electrochemical impedance spectroscopy(EIS) were used to analyze the internal structure, physical morphology, crystalline form and photoelectrical properties of the catalyst. The results showed that the introduction of TEOS had almost no effect on the crystal structure and band gap of the catalyst, while it could increase the specific surface area, pore volume and pore size of mpg-CN, thus providing more active sites. mpg-CN had lower photogenerated carrier recombination rate, higher photogenerated carrier separation efficiency and mobility, which was beneficial to the improvement of photocatalytic activity. To test the photocatalytic activity and product selectivity of the catalyst with different atmospheres and solvents conditions, a lignin model compound 1(2-phenoxy-1-phenylethanol) was used as the substrate. The results showed that under the conditions of catalyst mpg-CN, illumination, O2 atmosphere and solvent of CH3CN for 7.5 h, the conversion rate of 2-phenoxy-1-phenylethanol can reach 98.06%, and the selectivity of C-C bond cleavage was 91.79%. The result of the capture experiment proved that the photo-generated hole(h+) was the main active substance in the induced reactions. mpg-CN also had good stability and recycling performance, and the conversion rate of model compound 1 was 93%-98% when it was recycled for 1-8 times. Furthermore, the catalyst also showed a high conversion rate of 93.18% for the photocatalytic conversion of complex dimer lignin model compound 1b(1-(3-methoxyphenyl)-2-(2-methoxyphenoxy)-propane-1-diol).
In order to improve the stability of anthocyanins and broaden their application in functional products, the preparation process of Rhododendron pulchrum flowers anthocyanin microcapsules was optimized by response surface methodology, which was made using gum acacia and whey protein as wall materials and anthocyanin as core material. The anthocyanin microcapsules were characterized by scanning electron microscope(SEM), Fourier infrared spectroscopy(FT-IR) and thermogravimetry(TG). The results showed that the optimal microencapsulation conditions for the preparation of anthocyanin microcapsules by spray drying were as follows: wall-core ratio of 4:1, inlet air temperature of 165℃, and feed flow of 500 mL/h. Under these conditions, the embedding rate of anthocyanin microcapsules was(89.28±1.05)%. SEM showed that anthocyanin microcapsules were uniform spherical particles with a diameter of about 4.0 μm, compact structure, no cracks and non-sticking. FT-IR analysis showed that R. pulchium anthocyanins was embedded in the film formed by gum acacia and whey protein. TG analysis showed that the quality of anthocyanins decreased significantly at 197.7℃. Comparatively, the significant mass loss of anthocyanin microcapsules could be found only at 237.5℃. The storage stability analysis showed that the retention rate of R. pulchium flowers anthocyanin microcapsules was significantly higher than that of unembedded anthocyanins owing to the influence of light and temperature.
On the basis of single factor experiment, response surface methodology(RSM) was used to optimize the ultrasonic-assisted extraction optimum process of saponins from Gleditsia sinensis Thorn(GST), and the inhibitory activities of the extracts on α-glucosidase and α-amylase were investigated under the optimal extraction conditions. The results showed that the optimal ultrasonic-assisted extraction conditions were solid-liquid ratio of 16:1(mL: g), ethanol volume fraction of 60%, ultrasonic time of 80 min and extraction temperature of 50℃. Under these conditions, the yield of total saponins was 13.28%±0.25%, and the IC50 value of α-glucosidase was (0.146±0.019) g/L, which was stronger than that of positive control acarbose with the median inhibitory concentration(IC50) value of (0.48±0.18) g/L. When the mass concentration of the extract was 2 g/L, the inhibition rate of α-amylase could reach 35.13%±0.58%, indicating that GST had the potential development into a drug for type II diabetes.
Amphoteric cellulose copolymers(CO-AC) adsorbents were prepared though free radical polymerization in one-pot process using cellulose as raw material and methacryloxyethyl trimethyl ammonium chloride(METAC), acrylamide(AM), 2-acryloamino-2-methyl-1-propane sulfonic acid(AMPS) as monomers and potassium persulfate as initiator. The structure and properties of CO-AC were characterized by elemental analyzer and fourier infrared spectrometer(FT-IR). It was found that active groups, e.g., quaternary amine, amide and sulfonic acid group were successfully introduced into the molecular chains of cellulose. Taking the removal rate and equilibrium adsorption capacity of CO-AC to NH4+ and H2PO4- as the evaluation indexes, the adsorption conditions were optimized and the influence of various factors on the adsorption capacity of CO-AC were also evaluated. The results showed that the adsorption capacity of the adsorbent, derived under the conditions of 1:2:3:3 molar ratio of cellulose glucose unit to AMPS, AM and METAC, was the best. In 50 mL of NH4+ and H2PO4- solution with a mass concentration of 150 mg/L, the maximum adsorption capacity of NH4+ was 77.4 mg/g when the addition amount of CO-AC was 100 mg and pH value was 7.0. The maximum adsorption capacity of H2PO4- was 61.2 mg/g, while the addition amount was 100 mg and the pH value was 5.0. The adsorption process of NH4+ and H2PO4- on CO-AC was well characterized by the quasi-second-order kinetic, internal diffusion of particle and Langmuir models, indicating that chemisorption and internal particle diffusion processes were the main rate-limiting steps, and the adsorption process was homogeneous monolayer adsorption.
The main chemical constituents of Euscaphis plants are triterpenoids, phenolic acids, flavonoids, lignans, sesquiterpenoids, etc. Modern research shown that the extracts and monomeric compounds of the Euscaphis plants had anti-inflammatory, anti-bacterial, anti-tumour, anti-hepatic fibrosis and other pharmacological effects. At present, species delimitation of Euscaphis was changed and it was not very clear whether there were differences in chemical composition between the different varieties. Through the systematic search and summary of the chemical composition and pharmacological effects of Euscaphis plants, and we deeply elaborated whether differences in chemical composition was existed between different species and possible differential components, in order to provide a reference for the classification, development and use of Euscaphis plants.
The effect of torrefaction on the quality of biofuel was investigated through a small torrefaction experimental equipment with rice husk(RH) and pine sawdust(PS) as the raw materials. The results showed that torrefied rice husk and sawdust exhibited an increase in fixed carbon content by 7.18% and 11.76%, compared with the raw materials. And the C element content with the largest increased of 3.50% and 5.80% for rice husk and sawdust, respectively. The contents of volatile matter and O element decreased significantly, and the content of H element also decreased slightly. The calorific value increased by 11.1%(RH) and 15.9%(PS), respectively. The hemicellulose contents in the torrefied rice husk and sawdust after reaching 300℃ were only 2.41% and 1.06%, respectively. The hemicellulose was decomposed both more than 90%. The relative content of lignin increased significantly, with the largest increases of 119%(RH) and 208%(PS), respectively. After biomass torrefaction, the internal fiber structure was destroyed and the grindability was improved. With the deepening of the torrefaction degree, the particles with the size below 0.15 mm increased significantly after torrefied rice husk being ground. The study found that oxygen-containing functional groups such as -OH and C-O were reduced, and the hydrophobicity of torrefied rice husk and sawdust increased by 28.08% and 25.66%, respectively, when torrefied at 250℃ for 30 min.
In this work, the biomass resource reserve and its potential application as energy source in China was first analyzed. Subsequently, the principle, technical route, and the influence factors of the biomass gasification polygeneration for biogas and biochar technology were comprehensirvely introduced. Furthermore, the typical cases of multiple gasification integrated systems adapted to different feedstocks forms were described and the biomass gasification technology was prespected. The successful implementation of biomass gasification co-production of biogas and biochar technology was of great importantce for China to establish a clean, low-carbon, safe and efficient energy system, increase the share of the renewable energy in national energy supply, and achieve the goal of carbon peaking and carbon neutrality.
In order to construct a new composite film material with all-component from biomass, ternary deep eutectic solvent consisting of choline chloride-oxalic acid dihydrate-glycerol(ChCl-OAd-Gly) was used to pretreat bagasse raw materials, and the treated residue was recombined with the dissolved components to obtain lignin-containing nanocellulose(LNC) by homogeniza-tion. The lignin-containing nanocellulose film(LNCF) functional materials was then prepared via vacuum-assisted and hot press methods. The influence of the lignin content on UV shielding properties, mechanical properties, water resistance, thermal stability and morphology of LNCF were studied using elemental analysis, atomic force microscopy(AFM), scanning electron microscopy(SEM), material universal tester, thermogravimetric analyzer and spectrophotometer. The results showed that with the lignin addition increase at 20% by volume, the lignin mass fraction in LNC increase 2-3 percentage point the diameter of LNC decrease slightly. The prepared LNCF exhibited good UV shielding effect, and the UV shielding rate in 200-400 nm and the visible light transmittance in 390-780 nm for LNCF-100% reached 99.68% and 65.46%, respectively. The addition of lignin enhanced the mechanical properties of LNCF, and its tensile strength increased from 76.61 MPa of LNCF-0% to 144.73 MPa of LNCF-100%. The hydrophobicity of LNCF was significantly improved. The water contact angle of LNCF-100% surface was 90.47°, and the water absorption rate of LNCF-0% without lignin reduced from 21.52% to 7.14%. Accordingly, the wet mechanical properties were maintained with the wet strength up to 77.3 MPa. Moreover, all six LNCF displayed good thermal stability, and the temperature of maximum pyrolytic weight loss was higher than 337 ℃。
Sugarcane bagasse(SCB), a by-product of the sugar industry, was used as a lignocellulosic raw material. In the present study, a ternary deep eutectic solvent(DES) composed of triethylbenzyl ammonium chloride(TEBAC) with strong phase transfer catalytic ability, non-toxic and harmless glycerol(GL) and high-valence Lewis acid aluminum chloride hexahydrate(ACH), was used to pretreat SCB. The effects of molar ratio of ternary DES, reaction temperature, reaction time and solid-liquid mass ratio on the content of each component in SCB and cellulase enzymatic digestibility were systematically investigated. The results showed that the optimal pretreatment conditions were as follows: the molar ratio of nTEBAC: nGL: nACH was 1:2:0.05, the pretreatment time was 30 min, the pretreatment temperature was 120℃ and the solid-liquid ratio was 1:15. Under these conditions, the lignin removal rate was (86.23±2.11)%, and the cellulose retention rate was (94.51±2.03)%. The conversion of enzymatic hydrolysis cellulose was (98.21±1.02)%, which was 2 times higher than that of untreated SCB, and the yield of glucose was(81.94±1.98)%, which was increased by 1.5 times. The results of SEM, FT-IR and XRD analysisshowed that ternary DES pretreatment could effectively remove lignin and hemicellulose from SCB, and the crystallinity of celluloseincreased from 41.19% to 65.87% after pretreatment. Importantly, DES still maintained good pretreatment performance after 5cycles of recycling, and the cellulose conversion rate and glucose yield reached (92.36±1.64)% and (74.45±1.12)%, respectively.
Aromatic aldehydes were important raw materials for the synthesis of fine chemicals such as dyes, spices, pesticides and drugs. Lignin was the second largest component in lignocellulosic biomass, and was the only renewable resource for producing aromatic compounds. Catalytic oxidation could transform lignin into highly functionalized aromatic aldehydes(e.g., p-hydroxybenzaldehyde, vanillin, syringaldehyde, etc.) under mild conditions, which was regarded as one of the effective ways to realize the resource utilization of lignin. Firstly, the structural characteristics and depolymerization mechanism of lignin were introduced, and the effects of lignin structure on the production of aromatic aldehydes were summarized and discussed. Then, recent progress in the preparation of aromatic aldehydes by oxidative depolymerization of lignin was introduced in detail from the methods of catalytic oxidative depolymerization methods(e.g., wet oxidation and alkaline nitrobenzene oxidation, catalytic oxidative depolymerization with homogeneous and heterogeneous catalysts, photocatalytic oxidation and electrocatalytic oxidation) and types of catalysts(e.g., metal salts and metal porphyrins, heteropoly acids and other homogeneous catalysts, metal oxides and perovskite oxides and other heterogeneous catalysts). Moreover, the upgrading and conversion of aromatic aldehydes into high value-added products such as 2-methoxy-4-methylphenol, aromatic nitrile, aromatic amides and new organic polymer materials were further summarized. Finally, the existing problems in the current research on lignin oxidative depolymerization were summarized, and the possible development direction in the future was proposed, which laid a foundation for lignin oxidative depolymerization and high value-added utilization.
Based on the theory of lignin-based polyurethane preparation, this article summarized the methods for binding lignin and polyurethane when polyurethane adhesives were prepared from lignin, and elucidated the research status of lignin and modified lignin for preparing polyurethane adhesives. Furthermore, the main modification methods of lignin for the synthesis of polyurethane adhesives were summarized, and the influence of lignin modification methods on the performance of polyurethane adhesives was also discussed. It can be found that the ultimate goal of modification of ligin is to convert the phenolic hydroxyl groups into alcohol hydroxyl groups, in order to improve the reaction activity between lignin and polyurethane. Finally, the development directions of lignin polyurethane adhesives were prospected.
Nitrogen and phosphorus doped mesoporous carbon(NPC) materials were prepared by carbonization activation at different temperatures, using lignocellulose as raw material, hexa p-carboxylphenoxy cyclotriphosphazene(HCPCP) as nitrogen and phosphorus dopant with NaOH as coactivator, and were characterized by SEM, XRD, XPS and Raman spectra. The sample activated at 650℃(NPC-650) exhibited a rich reticular pore structure, with the average pore size of 5.18 nm, and the mesopore volume ratioreached 89%. A new zinc ion hybrid capacitor was assembled using NPC-650 as cathode material. Electrochemical performance tests showed the specific capacitance was 194 F/g at 0.2 A/gcurrent density, the energy density was 87.3(W·h)/kg, and the power density was 179.5 W/kg. The capacitance retention rate was 98.9% after 5 000 charging and discharging cycles under the current density of 10 A/g.
Using Bambusa pervariabilis as the raw materials the effects of acetic acid on the pulp yield, hardness, fiber crystallinity, fiber morphology and paper performance in ethanol pulping were studied. The results showed that the pH value of the solution decreased significantly from 7.3 to 4.1 after 2.0% acetic acid was added. The yield of coarse pulp decreased from 46.64% to 43.14%, which accelerated the degradation of carbohydrates. The Kappa number of pulp decreased from 52.31 to 48.90, which promoted the lignin removal during cooking. The relative molecular weight of lignin increased when the dosage of acetic acid was lower than 6%, while the relative molecular weight of lignin reduced when the dosage of acetic acid was higher than 6%. The addition of acetic acid made the coexistence of lignin degradation or condensation. The average length of the double mass(Lw) decreased from 1.72 to 1.58 mm, and the average width of the doublemass(Ww) decreased from 25.27 to 19.37 μm, which could make the fiber shrink and hard. The loose thickness and tear index of the finished paper were improved after adding acetic acid. The loose thickness increased from 2.16 to 2.30 cm3/g, and the tear index increased from 130.67 to 133.33(mN·m2)/g. The tensile index, flexability and break resistance decreased significantly. The tensile index decreased from 19.06 to 14.37(N·m)/g, the flexability decreased from 6 times to 3 times, and the break index decreased from 1.0 to 0.7 (kPa·m2)/g. The fiber crystallinity decreased from 54.67% to 48.71%. Acetic acid would destroy the fiber crystal zone, and the fiber crystallinity gradually decreased with the increase of acetic acid dosage, while the crystal zones of natural cellulose did not change.
An antifreezing soybean protein-based gel electrolyte was prepared by thermally induced polymerization using soybean protein(SPI), acrylamide(AAm) and ZnCl2 as raw materials. The effect of temperature on its ionic conductivity and mechanical property was investigated, and the mechanism was then analyzed. The results showed that the gel electrolyte had excellent frost resistance, and the introduction of ZnCl2 leaded to the formation of numerous Zn2+ solvation structures, which broke the hydrogen bonds among water molecules and reduced the freezing point of gel electrolyte. The synergistic effect of gel matrix and salt ions gave the gel electrolyte high compression resilience and fatigue resistance. The analysis of low-temperature ionic conductivity showed that when the ZnCl2 concentration exceeded 5 mol/kg, the ionic conductivity of gel electrolyte was still 3.65×10-3 S/cm at -30℃. The analysis of mechanical properties at low temperatures showed that the gel electrolyte could keep structural integrity after 100 compression cycles of 80% strain at -30℃, the stress retention remained more than 85% and the plastic deformation maintained 15%. At the same time, the gel electrolyte-based electrochemical capacitors assembled by gel electrolyte exhibited satisfied low-temperature resistance, which could work normally at -30℃ and maintain capacitance retention of 83.2%. The capacitance retention reached 92% after 10 000 cycles of charge and discharge at -30℃.
Using carbon by-products produced by bamboo gasification as raw material and the polymerized modified tar as the binder, the bamboo formed activated carbon was obtained by hydro-forming, pyrolytic cross-linking and followed by water vapor activation. The forming mechanism of different binders were analyzed, and the properties of activated carbon were investigated, such as the variety of the binder, the adding amount of modified tar, the activation temperature and the activation time. The results showed that after modification by aromatization and cross-linking, the molecular weight and thermal stability of tar were improved; the blocking effect of bamboo char pore channels was reduced; the bonding and pyrolytic cross-linking between char particles were enhanced; and high-performance bamboo forming activated carbon could be prepared. Using 40g bamboo charcoal as raw material, the tar addition amount of 12 g, the carbonization temperature of 550 ℃, the carbonization time of 90 min, the activation temperature of 850 ℃ and the activation time of 80 min, the iodine adsorption value of the formed carbon was 1 232 mg/g, the methylene blue(MB) adsorption value was 240 mg/g, the strength was 91%, and the yield was 48.5%. The specific surface area and total pore volume were 1 157 m2/g and 0.478 1 cm3, respectively. The adsorption rates of toluene and carbon tetrechloride were 385 mg/g and 75.2%, respectively. And the adsorption rate of toluene and carbon tetrechloride was positively related to the micropore volume of formed activated carbon.
In the present study, the microstructure of Gelsemium elegans vegetative organs was observed, and the alkaloids in plants were localized. Also, the antibacterial activity of the alkaloids was explored, and the antibacterial mechanism of the alkaloids was analyzed. The anatomical study of the structural characteristics of G. elegans vegetative organs was carried out with anatomical methods, and through histochemical staining, the alkaloids in the plant were localized. Microscopic observation results showed that the structure of G. elegans performed the typical characteristics of the dicotyledonous plants; the leaf of G. elegans was dorsiventral, and there were starch granules deposited in stem pith. The histochemical results showed that the vegetative organs of G. elegans contained alkaloids. Alkaloids were mainly distributed in the mesophyll tissue of leaves. In the stem, alkaloids were mainly distributed in stem epidermis, cortex cells and phloem parenchyma cells. Also, alkaloids were distributed in parenchyma cells of pith and ray cells. Yellow-brown sedimentation also could be observed in the cork cambium, the inner layer, the cortex, phloem parenchyma and ray cells of the rhizome. The antibacterial activity results showed that the G. elegans alkaloid had antibacterial activity against Listeria monocytogenes ATCC19115, Staphylococcus aureus ATCC25923, Staphylococcus aureus CMCC26003, Escherichia coli ATCC25922, Escherichia coli O157, Pseudomonas aeruginosa ATCC27853, and Pseudomonas aeruginosa CMCC10104. With the increase of alkaloid concentration, the antibacterial effect was also enhanced. The inhibitory effect on Listeria monocytogenes was the most obvious. After treatment with its minimum inhibitory and lethal concentrations, the morphology and internal structure of Staphylococcus aureus ATCC25923 and Escherichia coli O157 showed that both two kinds of bacteria changed in different degrees, such as rough surface, depression, rupture of the cell membrane and cell wall, overflow of internal substance and even cell lysis. The morphology of S. aureus changed at the minimum inhibitory concentration and the cell wall of E. coli was stratified. This indicated that G. elegans alkaloid destroyed the permeability of the cell membrane, impeded the formation of the cell wall, and lysed the bacteria. The cell death at the minimum lethal concentration might be caused by the loss and cleavage of the mechanical strength and permeability of the wall.
Bamboo was pretreated by choline chloride(ChCl)/1, 4-butanediol(BDO)/AlCl3 deep eutectic solvent(DES) system with a solid to liquid ratio of 1∶4(g∶g) at 90-130 ℃. The effects of DES reaction system with high loading capacity of lignocellulose on chemical composition, enzymatic hydrolysis efficiency, and lignin recovery of moso bamboo were investigated at different temperatures. The results of the research showed that the mass fractions of xylan and lignin in the pretreated substrates decreased gradually with the increase of pretreatment temperature, while the mass fraction of glucan increased, and the enzymatic hydrolysis efficiency increased significantly. When conducting pretreatment at the optimal condition of 110 ℃, the recovery rate of pretreated substrates was 59.24%, and the recovery rate of glucan and xylan were 91.38% and 27.03%, respectively. The lignin removal ratio was 69.72%, and the glucan enzymatic hydrolysis yield reached almost 100%, indicating that the ChCl/BDO/AlCl3 ternary DES system could greatly improve the pretreatment efficiency of moso bamboo. Further research showed that more than 90% lignin in the pretreatment liquid could be recovered by sequential organic solvent dissolution and reprecipitation, and the purity of the recovered lignin had high value of 99.26%. From the mass balance, it was found that each component of moso bamboo could be separated and transformed effectively.
In order to explore the effect of delignification under different organic solvent-assisted alkaline hydrogen peroxide treatment, the composition changes of poplar mechanical pulp after lignin removal by ethanol alkaline hydrogen peroxide(EAHP) and dioxane alkaline hydrogen peroxide(DAHP) were investigated using the alkaline hydrogen peroxide system(AHP) as a reference. The chemical structure, molecular weight, and hydroxyl content of alkali lignin(AL) and alkaline hydrogen peroxide lignin(AHPL), ethanol alkaline hydrogen peroxide lignin(EAHPL) and dioxane alkaline hydrogen peroxide lignin(DAHPL) were characterized by high-performance liquid chromatography(HPLC), Fourier transforms infrared spectroscopy(FT-IR), gel-permeation chromatography(GPC), and 31P nuclear magnetic resonance(31P NMR). The results showed that the three reaction systems led to the varying degradation degrees of the material yield and the dissolution of a large number of hemicellulose. Compared with AHP and DAHP, EAHP was more conducive to preserve cellulose and dissolve more lignin, and the highest lignin removal rate reached 65%. Compared with AL, AHP, EAHPL and DAHPL possessed basically the same infrared spectral peak type, both belonging to G-S type. The minimum Mn of the prepared lignin was 4 672 g/mol with low polydispersity and low phenolic hydroxyl content, while it had higher aliphatic hydroxyl group and carboxylic acid hydroxyl group contents, with the highest contents of 14.95 and 1.25 mmol/g, respectively.
In order to realize the preparation of morphologically controllable hydrothermal carbon microspheres, the effects of hydrothermal reaction conditions(reaction temperature, reaction time and reactant addition) on the morphology and physicochemical structure of the products were systematically studied using bamboo pulp fiber as a raw material. The obtained hydrothermal carbon was investigated by SEM, XRD, FT-IR and other characterization methods. The results showed that when the reaction temperature was 220℃, the reaction time was 6 h and the amount of reactant was 6 g, the carbon microspheres were dispersed and the size distribution was relatively uniform. The highest carbon fixation rate of the sample reached 24.3%, indicating that the preparation of hydrothermal carbon had a good carbon fixation ability. XRD results showed that hydrothermal carbon was an amorphous crystal. Functional gronp analysis showed that the surface of hydrothermal carbon was rich in a series ofoxygen-containing functional groups such as hydroxyl, carbonyl, ester and ether bonds. Elemental analysis showed that hydrothermal carbon had preferably carbon fixation ability. The specific surface area of the products ranged from 23.2-83.7 m2/g, and the pores were mainly mesopores. The main distribution range was 3-8 nm, and the maximum pore volume was 0.35 cm3/g.
The ethanolic extracts of Eucommia ulmoides Oliv. leaves were isolated and purified, where thirteen compounds were obtained, including one new compound and twelve known compounds. The structures of the compounds were identified by spectral data as follows: (R, 9Z, 12E, 15Z)-11-hydroxyoctadeca-9, 12, 15-trienoic acid(1), 7-hydroxycoumarin(2), astragaline(3), quercetine(4), quercetin-3-O-glucoside(5), 2-(3, 4-dihydroxyphenyl)-5, 7-dihydroxy-3-[(3-O-α-D-xylopyranosyl-α-D-galactopy-ranosyl)oxy]-4H-1-benzopyran-4-one(6), (2R, 3S)-3-(4-hydroxy-3-methoxyphenyl)-3-methoxypropane-1, 2-diol(7), (2S, 3R)-3-(4-hydroxy-3-methoxyphenyl)-3-methoxypropane-1, 2-diol(8), chlorogenic acid(9), gardendiol(10), 4-benzyloxy benzoic acid(11), vanillic acid(12) and myristic acid(13). Among them, compound 1 was a new fatty acid compound. The anti-neuroinflammatory and neuroprotective activities of 13 compounds were studied. The results showed that compounds 4, 5 and 10 exhibited significant anti-neuroinflammatory activity by inhibiting the release of nitric oxide(NO) production in lipopolysaccharide(LPS)-induced in mouse microglia(BV-2 cells), with half inhibitory concentration(IC50) values of (10.8±0.9), (9.7±1.1) and (10.7±0.3) μmol/L, respectively. Compound 5 exhibited significant neuroprotective activity under oxidative stress. After pretreatment with 20 μmol/L H2O2-induced rat adrenal pheochromocytoma cells(PC-12 cells), the cell survival rate was (86.5±0.5)%, which was higher than that of the positive control hesperidin.
Using the staged conversion strategy, the lignin component in furfural residue(FR) was first prepared into lignin-based dispersant(LS). When the mass of FR was 100 g, the mass of the deionized water was 1 000 g, the reaction temperature was 70℃, the reaction time was 3 h, the dosage of sodium hydroxide was 6.5 g, sodium sulfite dosage was 1.6 g, and formaldehyde dosage was 0.2 g, the dispersing force of LS was 105%. Subsequently, water absorption resin was further prepared from the separated cellulose residue. The effects of the reaction temperature, the amount of initiator ammonium sulfate(APS), crosslinking agent N, N'-methylene bisacrylamide(MBA) and the total amount of complex monomer acrylic acid(AA) and acrylamide(AM) on the water absorption of the water-absorbing resin were investigated. Under the optimum conditions of the neutralization degree of acrylic acid of 60%, the initiation time of 0.5 h, the amount of complex monomer of 9 g, the amount of initiator of 1.3 g, crosslinking agent dosage of 0.05 g, the reaction temperature of 52℃, and the graft copolymerization reaction time of 3 h, the water absorption of the water absorbent resin reached 64.6 g/g. FT-IR analysis showed that the grafting reaction of AM, AA and cellulose residue occurred. SEM images showed that theproduct with cross-linked network structure was formed in the reaction; thermogravimetric analysis showed that the introduction of AA and AM improved the thermal stability of the water absorbent resin; XRD revealed that the grafting reaction of AA and AM took place on the skeleton of cellulose residue.
Seventeen tetrahydrolinalyl amides(2, 4a-4p) were designed and synthesized using tetrahydrolinalool as starting material. Their structures were characterized by FT-IR, 1H NMR, 13C NMR and HRMS, then the herbicidal activities against Lolium perenne and Echinochloa crusgalli were evaluated. The results showed that the tetrahydrolinalyl amides exhibited certain growth inhibitory effects on L. perenne and E. crusgalli. Compounds 2, 4a, 4o showed the best pre-emergence herbicidal activity against L. perenne, where the inhibitory concentration 50%(IC50) values for the root growth of L. perenne were 0.05, 0.05, and 0.04 mmol/L, respectively(weaker than that of the positive control glyphosate), and the IC50 values for the shoot of L. perenne were 0.06, 0.05, and 0.05 mmol/L, respectively(stronger than that of glyphosate). The IC50 values of compound 4b on root and shoot growth of E. crusgalli were 0.06 and 0.15 mmol/L(equal to that of glyphosate), respectively. The structure-activity relationship analysis showed that tetrahydrolinayl amides exhibited selectivity among different weed species. The compounds containing alkyl group showed higher herbicidal activity than that of benzene ring and furan ring. The herbicidal activity of compounds with electron-donating group on benzene ring was stronger than that with electron-withdrawing group, exhibiting better activity when it was located at the ortho- and meta-position of benzene ring.
Nickel-based supported molecular sieve catalysts were prepared by excessive impregnation with different auxiliary methods using molecular sieve as the carrier. The catalytic pyrolysis performance of the nickel-based molecular sieve catalysts on the hydrogen carrier of biomass tar aromatic hydrocarbon-toluene to produce hydrogen was studied in a fixed-bed reactor. The effects of different molecular sieves, auxiliary methods and process conditions were investigated, and the service life of the catalyst was studied. The catalysts were characterized by XRD, SEM and BET. The results showed that the Ni/HZSM-5 molecular sieve catalyst using HZSM-5(the ratio of silicon to aluminum was 25) zeolite as the carrier had the highest catalytic activity, through the ultrasonic-assisted impregnation method, and the ultrasonic time was 20 min, the ultrasonic power was 80 W, and the Ni loading was 8%. At 700℃ and 40 min, the yields of H2 and CH4 were 76.6 mL/g and 27.6 mL/g, respectirely, and the total gas yield reached 108.9 mL/g. The toluene conversion rate was 76.8%, and the carbon deposition was 238.2 mg/g. The specificsurface area, the total pore volume and the average pore size of the catalyst were 241.8 m2/g, 0.19 cm3/g and 3.16 nm, respectively. The Ni loading did not affect the crystal structure of HZSM-5 obviously, while it exhibited an excellent catalytic activity. The stability of Ni/HZSM-5 catalyst was improved, and the service life was also extended. The catalytic hydrogen production performance of toluene was better than that of tetralin, phenol and acetic acid.
On the basis of static experiments, the purification effects of polysaccharides on 14 kinds of macroporous adsorption resins(S-8, ADS-F8, LSA-21, LSA-10, HP-20, ADS-17, NKA-9, DM130, AB-8, X-5, H103, D101, XAD-8, DA201) from Codonopsis pilosula(Franch.) Nannf. extraction were compared, and the better resin ADS-F8 was selected for dynamic adsorption. Based on the single factor experiments, the weighted comprehensive score of polysaccharides retention rate, decolorization rate and protein removal rate were used as the response values, and the response surface methodology was used to optimize the purification conditions of C. pilosula polysaccharide by macroporous resin. Meanwhile, the whitening activity, moisture absorption and moisture retention of the purified polysaccharides were tested. The results showed that the optimal purification conditions were as follows: loading concentration of 1 g/L, eluting volume of 150 mL, flow rate of 100 mL/h, and sample volume of 150 mL. Under these conditions, the comprehensive score of purification was (73.12±0.06)%(n=3), which was close to the predicted value of 73.02%. The purified polysaccharides had favorable whitening activity, and the half inhibitory mass concentration(IC50) value of tyrosinase monophenase was 3.20 g/L, which was similar to the inhibitory effect of whitening agent phenylethylresorcinol. The IC50 value of bisphenolase was 7.96 g/L, which is higher than phenylethylresorcinol of 0.73 g/L. When the air humidity was 43%, the purified polysaccharide showed strong hygroscopicity, and the highest moisture absorption rate was 123.01% at 12 h. In four air humidity conditions, the purified polysaccharides, crude polysaccharides and their mixture with a volume ratio 1∶1 to glycerol all had high moisture retention, especially, the moisturizing property of the mixture was better, and the moisturizing rate reached 99.95% within 12 h, which was significantly better than that of purified polysaccharide and crude polysaccharide.
The primary network was formed by using ethanol vapor to induce the microcrystalline cellulose(MCC)-sodium hydroxide/urea solution. The acrylic acid(AA) and acrylamide(AM) were chosen as raw materials, together with N, N′-methylene bisacrylamide(MBAA) as a cross-linking agent, and ammonium persulfate(APS) as an initiator to fabricate the secondary network. Then, ferric chloride was introduced by soaking method to construct a multi-crosslinked cellulose/polyacrylamide-polyacrylic acid/ iron ion hydrogel(C/PAMAA/Fe3+). The mechanical and electrochemical properties of the hydrogel were investigated. The results showed that the coordination bond formed by Fe3+ and —COO- acted as a sacrificial fracture during deformation, which contributed to the improvement of the mechanical properties of C/PAMAA/Fe3+. The hydrogel showed the toughness of 17.13 MJ/m3 and tensile strength of 4.59 MPa, respectively. Moreover, the results of the cyclic tensile loading-unloading test showed that the energy dissipation efficiency of the C/PAMAA/Fe3+ hydrogel increased with the increase of Fe3+ concentration, and the energy dissipation rate increased from 56.86% to 75.17%. Besides, the elastic recovery after the second cyclic loading-unloading could reach around 85.0%. As the increasing concentration of Fe3+, the ionic conductivity of the C/PAMAA/Fe3+ hydrogel increased, and a Fe3+ concentration of 0.2 mol/L was 1.03 S/m. The C/PAMAA/Fe3+ hydrogel was assembled as a strain sensor, and the sensitivity was 4.0. The resistance change results of the stretching increment and stretching cycle showed that the C/PAMAA/Fe3+ hydrogel strain sensor had good stability. The results of real-time monitoring of joint activities showed that the sensor had a stable strain response.
Citric acid carbon dots(CDs) were prepared by a one-step hydrothermal method using citric acid as carbon source. The afterglow aerogel CDs@CNF was prepared by doping CDs into cellulose nanofibers(CNF) after physical cross-linking. The red afterglow aerogel CDs-RhB@CNF was prepared by triplet-to-singlet Förster resonance energy transfer(TS-FRET) strategy using CDs as donor and rhodamine B(RhB) as acceptor. The photophysical properties and microstructure of the aerogel were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), ultraviolet-visible(UV-Vis) absorption spectrum, steady-state transient fluorescence spectroscopy and International Commission on Illumination(CIE) chromatograms. The results showed that, the phosphorescence lifetime of CDs@CNF at 535 nm was 144.88 ms, the CDs were uniformly distributed in the CNF aerogel, which had a honeycomb porous structure. The phosphorescence lifetime of CDs-RhB@CNF at 600 nm was 102.49 ms, and the Förster transfer efficiency was up to 65.9%. The yellow afterglow aerogel CDs-Rh6G@CNF and CDs-Rh123@CNF were obtained by doping rhodamine 6G(Rh6G) and rhodamine 123(Rh123) with fluorescent dyes, and the aerogel-loaded phosphorescent paper was further applied in the field of aesthetic origami and advanced anti-counterfeiting, extending the strategy and application area of preparing multicolor afterglow materials from natural biomass.
The extracts of Qinan(QN) and traditional agarwood(TA) were prepared by cold extraction(CE) and hot extraction(HE) with water and ethanol as solvent, respectively. The chemical constituents of the extracts were analyzed by GC-MS and HPLC, and their antioxidant and antibacterial activities were studied. The results showed that the species of sesquiterpenoids in QN were less than those of TA, while the contents of sesquiterpenoids in both were higher than that of TA. There was almost no tetrahydro-2-(2-phenylethyl) chromones(THPECs) in QN, and Flidersia type 2-(2-phenylethyl) chromones(FTPECs) was contained, where the mass fraction of 2-(2-phenethyl) chromone could reach 10.87%, and the mass fraction of 2-[2-(4-methoxy)phenethyl]chromone was 4.80%. The species and contents of THPECs in TA were rich, and the mass fraction of agartetrol could reach 1.50%. With the increasing ethanol volume fraction(0-55%), the ABTS free radical scavenging ability and iron ion reduction ability of QN and TA extracts increased. Although the antioxidant activity of QN water extracts was lower than that of TA, while its ethanol extracts were higher than that of TA. QN and TA had no significant antibacterial activity against Escherichia coli, but their water extracts had antibacterial activity against Candida albicans.