The cellulose dissolution capability and dissolution mechanism of current novel solvent systems, including aqueous solvent systems (NaOH aqueous solution, alkali/urea and NaOH/thiourea aqueous solution, quaternary ammonium/phosphine aqueous solution, and molten inorganic salt hydrates) and organic solvent systems (LiCl/N, N-dimethylacetamide, ionic liquids and deep eutectic solvents) were reviewed. Sequentially, the advantages and disadvantages of various solvents were discussed, which could provided a reference for the future development and utilization of green cellulose solvents.
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.
The degradtion of condensed tannin to tannin oligomers or monomers with low molecular weight is of great significance for improving their bioavailability and realizing high value-added utilization. This article comprehensively summarizes the research progress of condensed tannins in the fields of microbial degradation (fungal, bacterial), chemical degradation (acid degradation, alkaline degradation, precious metal catalytic degradation and biological enzymolysis), resin catalytic degradation, etc. The problems and solutions are summarized, and the future development direction is prospected.
pH-sensitive micelles BUDA-pentanolamine-(mPEG-NH2) (BPAU) were synthesized with traditional pH-sensitive micelle materials 5-amino-1-pentanol (pentanolamine), 1, 4-butanediol diacrylate (BUDA) and amino group functionalization methoxypolyethylene glycol (mPEG-NH2) as raw materials by self-assembly. Then, with trieneurushiol phenol borate derivative (URU-NH2) as the hydrophobic unit and galactose (Gal) as the recognition unit, the pH-sensitive BPAU-NH2-Gal nanomicelle was synthesized. And then, Paclitaxel (PTX) was used as the test drug, and nano-drug loaded micelles (PTX@BPAU-NH2-Gal) were prepared by dialysis. By nuclear magnetic (NMR), gel chromatography (GPC), surface/interfacial tension, Zeta potential analysis, micelle structure, average relative molecular mass (Mw) and critical micelle concentration (CMC), Zeta potential were characterized. The morphology of drug-loaded micelles was characterized by TEM, and the particle size was determined by DLS.High-performance liquid chromatography (HPLC) was used to determine the encapsulation efficiency and drug loading quantity of PTX. Dynamic membrane dialysis was used to investigate the release and uptake characteristics of drug-loaded micelles at different pH values in vitro. The results showed that BPAU-NH2-Gal was synthesized successfully, and the Mw value of micelle BPAU-NH2-Gal was about 15 550, dispersion index (PDI) was 1.49, the CMC value was about 90.29 mg/L, and the Zeta potential value was 29.69 mV. The drug-loaded micelle PTX@BPAU-NH2-Gal had an irregular elliptical structure with the average particle size about 195 nm; the encapsulation rate of paclitaxel was 92.51%, the drug load quantity was 31.76%.When the pH value was 4.5, the release rate was significantly higher than that in the environment with pH value of 6.8 and 7.4, and the micelle release had obvious pH responsiveness property.When the pH value of the buffer solution was 4.5, 6.8, and 7.4, the cumulative release rate of paclitaxel from the drug-loaded micelle within 90 h were 50.00%, 34.26% and 9.00%, respectively, which showed low toxicity to LO2 and high activity against HepG2.
5-hydroxymethylfurfural (HMF), an important precursor for biofuel production, can be prepared via dehydration of carbonhydrates such as cellulose. In this study, titanium tetraisopropanolate and zirconium n-butoxide with different molar proportion were used as the precursor to prepare binary oxides (TiZrO). Phosphorus was introduced to enhance the acidity of catalyst and to obtain TiZrPO. TiZrPO-1, TiZrPO-2 and TiZrPO-3 catalysts were prepared, when n(Ti):n(Zr) was 7:3, 1:1 and 3:7, respectively. The structures of these catalysts were characterized by XRF, STEM, FT-IR and NH3-TPD, and the catalytic performance for the conversion of fructose and glucose to HMF was tested. The characterization results suggested that Ti, Zr and P distributed evenly in the catalysts. Moreover, the distribution of Brønsted acid and Lewis acid could be controlled by adjusting the value of n(Ti):n(Zr). When n(Ti):n(Zr) was 1:1, the amount of Brønsted acid reached the maximum (2.55 μmol/g) in TiZrPO-2, and the corresponding Brønsted acid to Lewis acid ratio (0.49) was also the highest. The catalytic performance of TiZrPO on the conversion of fructose and glucose showed that, among the three catalysts, TiZrPO-2 had the best catalytic performance with 98.5% conversion of fructose and 76.5% yield of HMF at 40 min, and 72.2% conversion of glucose and 38.1% yield of HMF at 180 min; when TiZrPO-2 was recycled and reused for 4 times, the conversions of fructose and glucose still reached as high as 92.7% and 65.8%, respectirely. While the corresponding HMF yields were 72.6% and 30.4%, respectively, which indicated that TiZrPO-2 had satisfying reusability. According to the product analysis for fructose, levoglucosan, etc., it was found that Lewis acid could promote the conversion of glucose to fructose, while side reactions involving fructose was also favored. Brønsted acid could accelerate the dehydration of glucose to levoglucosan, and it also catalyzed the direct dehydration of fructose and glucose to HMF.
Using residual carbon powder from sawdust gasification as raw material, the formed activated carbon was obtained by adding activating agent(calcium hypochlorite), binders(carboxymethyl cellulose sodium, asphalt, phenolic resin), and then carrying out carbonization and water vapor activation process. The properties of activated carbon were influenced by many factors, such as the types of the binders, the adding amount of binders and activation agent, and the conditions of the water vapor activation. The aforementioned factors were investigated amply. It was found that the formed activated carbon with good properties could be prepared by using asphalt and phenolic resin as binder alone or in combination. The addition of activation agent could improve the adsorption performance of activated carbon, but reduce the strength and yield. Adding activating agent(0.3 g), the activated carbons were prepared by water vapor activation(850℃, 45 min, 1.5 mL/min) via three molding modes:AC1 with asphalt(addition amount 25 g) as binder, and AC2 with phenolic resin(addition amount 6 g) as binder, AC3 with the mixture of asphalt(addition amount 10 g) and phenolic resin(addition amount 3 g) as binder. The maximal iodine adsorption value was over 900 mg/g, the maximal methylene blue adsorption value reached 180 mg/g, the maximal strength was 99%, and the maximal yield was 32.9%. The pore size of activated carbon was mainly microporous, and the maximal micropore content was over 83%. The maximal specific surface area and total pore volume were up to 697.04 m2/g and 0.38 cm3/g, respectively.
The mechanism of 5-hydroxymethylfurfural(5-HMF) pyrolysis was studied by density functional theory B3LYP/6-31G++(d, p). The results show that the energy barrier of generating furfural by hydroxy side chain removal of 5-HMF is 322.8 kJ/mol, and the energy barrier of 2-furfuryl alcohol by aldehyde group side chain removal of 5-HMF is 375.4 kJ/mol. It is indicated that the appearance of furfuryl is earlier than 2-furfural in the pyrolysis process of 5-HMF. Further pyrolysis of furfural can occur the ring-opening reaction to form benzene ring with the reaction energy barrier of 370.8 kJ/mol, which explains that the furan ring can undergo deoxygenation and cyclization reaction. 5-HMF can directly generate ring-opening reaction in the case of H2O participation or without H2O participation to obtain enol compounds or enone compounds. The energy barrier of ring-opening reaction with H2O participation is 287.6 kJ/mol, and the energy barrier of ring-opening reaction without H2O participation is 279.1 kJ/mol. Thus, the participation of water molecules is not conducive to the ring opening of 5-HMF.
The deprotonation process of a typical tannic acid, 1, 2, 3, 4, 6-penta-O-galloyl-β-D-glucopyranose(PGG), and its parent compound methyl gallate(MeG) was studied by pH potentiometric titration and spectrophotography. The dissociation constants of PGG and MeG were calculated by chemometric methods using the Reactlab Equilibrium software. Concentration profiles of the fully protonated PGG and its two deprotonated forms at different pH values were also predicted by the chemometric method. The results showed that the deprotonation of phenolic hydroxyl of PGG was found with the increasing of pH value, and fully deprotonated forms of PGG existed at pH>11. These formed negative ions of oxygen can further coordinate with metal ions. Spectroscopic studies showed that there were two deprotonated forms of PGG, and the corresponding pKa values were 10.84±0.03 and 10.62±0.02. There was only one deprotonated form of MeG during titration, and the corresponding pKa value was 9.68±0.02.
Global warming caused by greenhouse gas emissions is a pressing environmental problem. Given that CO2 is the most significant greenhouse gas, research into materials that can efficiently adsorb CO2 has attracted considerable attention. Compared with other adsorption materials, porous materials offer a large specific surface area with high chemical and thermal stabilities and also feature good adsorption capacity, selectivity, cyclicity, and fast adsorption kinetics; therefore, they are widely used as solid adsorbents for CO2 capture. This review systematically introduces five types of porous carbon materials coal/petroleum-coke-activated carbons, biomass porous carbons, carbon aerogels, metal-organic-framework-derived carbons, and carbon nanomaterials that have been developed in recent years. Furthermore, the four primary methods used to prepare these materials for CO2 adsorption (i.e., high temperature carbonization and activation, hydrothermal carbonization, sol-gel processing and the template method) are presented. Emphasis is placed on their structure-performance relationship with CO2 adsorption. Simultaneously, the mechanism whereby CO2 is adsorbed by porous carbons with a pore texture is reviewed, in addition to the surface chemistry. Lastly, current challenges pertaining to CO2 adsorption are summarized, and future development trends are also prospected.
The preparation of biofuels by catalytic hydrogenation from the pyrolysis products of Swida wilsoniana oil was studied. The catalytic hydrogenation process was investigated and optimized by single factor test and response surface experiments. The optimum parameters obtained by single factor test were catalyst dosage 1.0%, reaction temperature 170℃, reaction pressure 2.0 MPa, reaction time 150 min and the maximum conversion was 96.3%. The optimal parameters obtained by response surface experiments were catalyst dosage 1.05%, reaction temperature 173℃, reaction pressure 2.0 MPa, and the highest catalytic conversion rate was 98.1%. It was found by GC-MS, elemental analysis and FT-IR that after hydrogenation, alkanes increased by 8.15 percentage points, oxygen content decreased from 10.502% to 2.392%, and biological hydrocarbon compounds increased significantly, with the mass fraction of 95.12%. At the same time, the carbon chain C3-C7 in biofuels increased by 4.31 percentage point and C8-C19 increased by 18 percentage point compared with that of pyrolysis products. The product structure was closer to the existing fossil fuels.
Using Myrica rubra leaves as raw materials and tea saponin as extraction enhancer, the ultrasonic-assisted extraction process was used to optimize the extraction process of myricetin by orthogonal test on the basis of single factor test, and the antioxidant activity of myricetin was investigated. The results showed that the best processing conditions for the extraction of myricetin were liquid-to-material ratio 15:1 (mL:g), ethanol volume fraction 80%, extraction temperature 70℃, extraction time 50 min, and the amount of surfactant tea saponin 0.3%. Under these conditions, the extraction yield could reach up to 1.33%. When the mass concentration was 3.0 mg/L, the scavenging rate of myricetin to DPPH· could reach 52.11% and the IC50 value was 2.670 mg/L; the scavenging rate of VC to DPPH· was 56.49% and the IC50 value was 2.363 mg/L. The ·OH scavenging rate of myricetin at the mass concentration of 120 mg/L reached the maximum of 64.21%, and the VC scavenging rate was 72.11%, and the IC50 values were 91.139 and 61.483 mg/L, respectively; it could be seen that myricetin had a better anti-oxidation ability, but the overall effect was slightly lower than VC.
Modified activated carbon(ACN)was prepared via dipping method with coconut shell activated carbon as precursor and urea and niacinamide as modification agents. Effects of surface chemical properties and pore structure on the adsorption performance of formaldehyde were investigated. The surface morphology, pore structure and surface functional groups were characterized by using scanning electron microscopy, N2 adsorption isotherm and X-ray photoelectron spectroscopy, respectovely of carbon. The results revealed that the loaded particles appeared on the surface and pore of the modified activated carbon, the specific surface area and total pore volume of the modified activated carbon decreased and the number of amide and quaternary ammonium functional groups and lactone class (-C=O) oxygen functional groups increased. As the mass fractions of urea solution was 9% and the mass fractions of nicotinamide was 0.5%, the modified activated carbon ACN3 had the most excellent adsorption capacity with the equilibrium adsorption capacity of 0.042 9 mg/g, which was 60.67% higher than that of the original activated carbon (0.026 7 mg/g), and was 2-3 times of commercial activated carbon.
To deeply understand the catalytic mechanism of bio-char on volatiles during biomass pyrolysis, a variety of functionalized graphenes, including RGO-OH, RGO-COOH and RGO-NH2, were used as functional-group-rich char models. The catalytic effect of these different surface functional groups on the typical lignin α-O-4 compound benzyl phenyl ether(BPE) at 400℃ was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results showed that -OH and -COOH significantly increased the degree of thermal decomposition of BPE. The conversion of BPE increased from 0.1% (without catalyst) to 37.73% (with RGO-COOH as catalyst) and 53.78% (with RGO-OH as catalyst), respectively. However, -NH2 only provided a BPE conversion of 12.29%, even weaker than the catalytic activity of non-functionalized reductive graphene oxide (RGO) (BPE conversion of 25.63%), indicating that the RGO as carrier also had a certain catalytic effect on BPE conversion, and -NH2 played an inhibitory role. The decomposition of BPE was mainly caused by the sp3 Cα-O bond cleavage, and the proudcts were mainly phenol and 2-benzylphenol. The surface oxygen-containing functional groups (-OH and -COOH) promoted the dimerization reaction, forming 2-benzylphenol and 4-benzylphenol. In addition, the functional groups also could promote the cleavage of sp2 Caryl-O, and the main product was benzaldehyde.
The type-I cardanol with allyl ester group(GMA-C) was synthesized by the reaction of cardanol and glycidyl methacrylate(GMA), and further reacted with methacrylic anhydride(MAA) to prepare the type-II cardanol with allyl ester group (MAA-GMA-C). The chemical structure of the products were characterized by FT-IR, 1H NMR and 13C NMR. The UV curing properties of the prouducts, mechanical properties and chemical resistance of the cured film were investigated. The results showed that the cardanols with allyl ester group could be cured under UV irradiation for 40 s, the pencil hardness of the film could reach 4H, the adhesion force could reach grade two, and the cured film had better properties of water resistance, ethanol tolerance and acid resistance.
In order to explore the preservation effect of rosin-based antistaling agent on postharvest citrus fruits, maleic rosin pentaerythritol ester(MRPE) was used as main component to prepare preservative, which was coated on ponkan for preservation and compared with uncoated ponkan and ponkan coated by morpholine fatty acid salt(MFAS) at room temperature storage conditions.Relevant indexes were measured every 6 days, and the results showed that after storing for 42 days, the weight loss rate of ponkan coated by MRPE coatings was 11.39%, which was 31.39% lower than that of the blank control group; firmness of ponkan coated by MRPE coatings was 1.61 N and the changes of firmness were lower than those coated by MFAS and the blank control; meanwhile, MRPE and MFAS coatings all could effectively inhibited the changes of soluble solids content and titratable acid content and the increase of malondialdehyde content(MDA). At the same time, the activities of superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) of ponkan coated by MRPE were increased which were 9.90, 1.26 and 1.02 U/g after storing for 42 days. These results showed that the preservation effect of MRPE coating treatment was better than that of MFAS treatment, which indicated that rosin resin had a good application prospect in postharvest preservation of ponkan.
Pollution by heavy metals is a serious environmental problem. Lignocellulose offers the advantages of high-capacity storage, renewability, and biodegradability, while offering excellent adsorption performance and being easy to recycle. As such, it is being increasingly used as a magnetic adsorbent for the removal of metal ions from polluted water. Starting with a brief description of magnetic nanomaterials, this review focuses on the preparation of cellulose-, lignin-, and hemicellulose-based magnetic adsorption materials, both domestically and overseas, summarizing and comparing their abilities to adsorb different heavymetal ions. In addition, the adsorption abilities and factors influencing the removal of different heavy metal ions are discussed in detail. Finally, future development directionsfor lignocellulose-based magnetic adsorbents are discussed.
Xylo-oligosaccharides(XOS), as one of the most effective prebiotics, are widely applied in medicine and health production, food additive, pet food and feed, etc. The production of XOS by enzymatic hydrolysis has the disadvantages of low efficiency, long production cycle and high cost, which is difficult for large-scale industrial production. Therefore, non-enzymatic production of XOS has become a hot spot in recent years. This paper introduced the chemical structure, physicochemical properties and biological properties of XOS. Then, the process, technological characteristics, XOS yield and relative merits of non-enzymatic catalysis methods(such as acid hydrolysis, steam explosion, autohydrolysis, subcritical CO2 and inorganic salt treatment) were systematically summarized. Finally, the suggestions for future research on XOS were provided based on the understanding of problems existing in the current research.
This review reports the progress of oil-based unsaturated polyester resins(UPR) in the last two decades, including plant oil resins cured via direct polymerization, traditional oil-based UPR, oil-based unsaturated ester resins, blending oil-based UPR, styrene-replacing oil-based UPR, etc. At last, the prospect of the oil-based UPR is described.
In order to improve the domestic pulp output and utilization rate, and alleviate the shortage of high-quality materials in the pulping and paper-making industry, a rapid analysis research was conducted on the specific material model of pulp making-Eucalyptus-Acacia mixed with pulpwood in southern China. The near-infrared spectra of 175 Eucalyptus-Acacia mixed samples and 45 single-species samples were collected. The mixing degree and chemical composition content of all samples were analyzed. The original spectra were preprocessed by the combined pretreatment methods of smoothing, vector normalization(V-Norm), multiple scattering correction(MSC), first derivative(1st Der) and second derivative(2nd Der). Combined with the least absolute shrinkage and selection operator(LASSO) algorithm, the mixing degree, holocellulose, Klason lignin, pentosan, benzene-alcohol extractives and 1% NaOH extractives content models were built. The optimal adjustment parameters determined during the modeling process were 13.62, 18.30, 6.39, 9.64, 7.49, and 12.07. The RMSEP values of the six models were 1.93%, 0.61%, 0.51%, 0.80%, 0.28%, and 0.41%, respectively. The absolute deviation ranges were -3.19%-3.24%, -0.96%-1.01%, -0.89%-0.84%, -1.37%-1.46%, -0.43%-0.39%, -0.58%-0.60%. The models have good adaptability and could meet the needs of the pulping and paper-making industry. It also confirmed the feasibility of the LASSO algorithm for the analysis of mixed pulpwood materials.
Isopimaric chloride(compound 2) was synthesized by using isopimaric acid as raw material. Then four new isopimaric thiophene sulfonamides derivatives:isopimaric acid acyl-4-bromo-2, 5-dichlorothiophene-3-sulfonamide(5a), isopimaric acid acyl-5-bromothiophene-2-sulfonamide(5b), isopimaric acid acyl-5-chloro-4-nitro-sulfonamide (5c), and isopimaric acid acyl-thiophene-2-sulfonamide(5d) were prepared by aminolysis reaction from compound 2 and thiophere sulfonamides which were connected with p-phenylenediamine. The structures of the compound were confirmed by FT-IR, 1H NMR, 13C NMR, and ESI-MS. In addition, the cell proliferation inhibition assay (MTT method) was used to study the in vitro inhibitory activity of 5a-5d on four human tumor cells. The results showed that compound 5b had inhibition rates of 91.36%, 94.06% and 92.26% against Hela, MDA-MB-231 and Hep G-2 at the concentration of 100 μmol/L, besides, the inhibition rate against PC-3 was 86.93%, which was close to 90%, indicating that compound 5b had good antitumor activity. Through the determination of IC50 value, it was further concluded that the inhibition effect of compound 5b was better than that of 5-fluorouracil (5-FU), a widely used anticancer agent in clinic.