Anthocyanin is a kind of flavonoid which mainly exists in plants. It has strong biological activities such as anti-cancer and anti-oxidation, and is widely used in the field of nutrition and health care. Most anthocyanins are extracted directly from plants by physical or chemical means, but the yield is low, and the extracted anthocyanins are mostly mixtures due to the restrictions of time, region and season. Biosynthesis of anthocyanins have attracted much attention by researchers worldwide in recent years. As the biosynthesis of anthocyanins can be controlled artificially and the purity of the obtained products is high, it has been widely studied. Anthocyanins cannot exist stably in the environment, and need to be modified by glycosylation, acylation and methylation to increase their stability. The modified anthocyanins can be synthesized by microorganisms and significant color changes can be seen in the medium. The biosynthesis and modification of anthocyanins were reviewed in this paper, and the preparation technology of anthocyanin synthesis from plants and microorganisms was briefly introduced, the factors affecting anthocyanin synthesis were analyzed, and finally the future research direction of anthocyanin was predicted.
Lignin is the most abundant renewable aromatic polymer in nature, which complex structure and compact connection with cellulose and hemicellulose through covalent bond and hydrogen bond make it difficult to be separated efficiently. Deep eutectic solvents (DES) is a novel kind of green ionic liquid, which has been successfully applied to lignin isolation due to its unique physical and chemical properties. The research progress of dissolution and extraction of lignin by deep eutectic solvents (DES) is reviewed in detail. From the point of view of the mechanism of dissolving lignin by DES, the effects of different factors(composition, proportion, pH value, functional groups of DES, water content of system, raw material, reaction time, temperature, catalyst, co-solvent, and so on) on lignin removal were emphatically expounded. Based on the research progress of DES in lignin extraction, the research progress and futuer application of lignin extraction were summarized and prospected.
The hydrophilic, ductile, thermoplastic and biodegradable properties of cellulose acetate (CA) were introduced, and the basic structure and market application of three kinds of cellulose acetate were summarized.It was pointed out that CA still had some disadvantages such as poor thermal stability at high temperature, low mechanical strength and easily being contaminated. The impacts of the physical modification and chemical modification on the properties of CA were also reassessed.It could conclude that the chemical reaction with polymer could change the structure or properties of CA.The fouling resistance, thermoplastic, selective and reuse of the CA were improved greatly, while the physical modification could improve the porosity and thermal stability of CA membrane, and the membrane mechanical strength, metal ion exclusion rate and the water flux were improved. The applications of CA in seawater desalination, adsorption of toxic substances in flue gas, preparation of biomedical membrane, drug delivery, tissue repair and regeneration, biosensor, outdoor protection and air purification were also summarized, and the market prospect and development trend of CA were prospected.
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.
A cellulose-based highly conductive film (RGO/CNF/RGO(RCR)) was prepared using graphene oxide (GO) and cellulose nanofiber (CNF). Graphene oxide@polypyrrole (GO@PPy) active material was deposited on both sides of the film, then an integrated flexible film with conductive anisotropy and good flexibility was acquired. Furthermore, the liquid electrolyte was infiltrated into the composite film, and the copper foil was used as the current collector to prepare the integrated sandwich structure supercapacitor(SC). The morphology and surface elements of the film were analyzed by scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Afterwards, the electrochemical performance of integrated capacitor was compared with stacked capacitor and gel capacitor. The results showed that PPy was wrapped on the surface of GO and deposited on the surface of RCR film in the form of GO@PPy, and a pseudo-capacitive layer of about 400 nm was formed. When the scanning rate was 5 mV/s, the area specific capacitances of integrated, stacked and gel capacitor reached the maximum, which were 28.5, 28.1 and 33.8 mF/cm2, respectively. When the scanning rate increased to 200 mV/s, the area specific capacitances decreased to 4.6, 3.2 and 1.1 mF/cm2, respectively. It could be seen that the integrated capacitor has higher stability. The tight and seamless connection of the integrated capacitor could effectively avoid the relative displacement and shedding between the adjacent components, and effectively reduce the resistance of electron/ion transfer. At the same time, the integrated capacitor also showed better flexibility, and its electrical performance remained stable after bending test. When the current density was 0.2 mA/cm2, the area and volume specific capacitance of the integrated capacitor could reach 64.8 mF/cm2 and 31.0 F/cm3, respectively, showing excellent electrochemical performance. The preparation of the integrated supercapacitor provides a new method for development of wearable electronic devices.
The lignin-based phenolic resin was synthesized by condensation reaction of phenol and formaldehyde, in which part of phenol was replaced with alkaline cornstalk lignin. To evaluate the effect of foaming agents on the structure property of the carbon foams, n-hexane, n-pentane and activated carbon loaded n-hexane were chosen as the foaming agents, and the prepared carbon foams were signed as CF-H, CF-P, and CF-ACH, respectively. The results indicated that the lignin-based phenolic foams prepared by different foaming agents exhibited excellent thermal stability, evidenced by the higher residual carbon recovery rate of 47.95% after thermal decomposition at 800 ℃. All of the prepared carbon foams belonged to amorphous carbon, in which non-graphitized carbonaceous structure was detected. The pore shape of CF-H, CF-P, and CF-ACH was spherical or ellipsoid with the pore size distribution of 20-300 μm, and their apparent densities ranged from 0.15 to 0.55 g/cm3. Compared with the normal carbon foams, the prepared lignin-based carbon foams had considerable compressive strength and the maximum compressive strength reached 13.13 MPa. In addition, the specific surface areas of CF-P, CF-ACH, and CF-H were 471.22 m2/g, 186.72 m2/g, and 42.08 m2/g, respectively. The pore opening rates of the carbon foams were all above 64%, and the area percentages of micropore were above 77%.
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.
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.
The anacardic acid based epoxy resin type-Ⅰ(EACA-Ⅰ) was synthesized by the reaction of anacardic acid(ACA) obtained from cashew nut shell liquid(CNSL) and epichlorohydrin. Then, the side chain oxidation of EACA-Ⅰ was carried out to form the anacardic acid based epoxy resin type-Ⅱ(EACA-Ⅱ). The chemical structure of the epoxy resins was characterized by HPLC, FT-IR and NMR. The epoxy values of EACA-Ⅰ and EACA-Ⅱ were 3.7 mmol/g and 6.0 mmol/g, and the viscosities at 25 ℃ were 80 and 300 mPa·s, respectively. The characterization of curing reaction and heat resistance of the cured products obtained from the reaction of epoxy resins with tetrahydromethyl-1, 3-isobenzofurandione(MeHHPA) and isophorondiamine(IPDA) were investigated by DSC and TGA, respectively. The results showed that the heat release of the curing process of the anacardic acid based epoxy resins with MeHHPA was moderate. However, the heat release of the curing process of anacardic acid based epoxy resin with IPDA was intense; the cured products obtained from the reaction of the anacardic acid based epoxy resins with MeHHPA showed good thermal stability with the initial temperature of degradation more than 371.6 ℃ and the peak temperature of weight loss at 417.5 ℃.
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.
Lignin-based activated carbon was prepared from corn cob lignin by using phosphoric acid activation method.Taking methylene blue adsorption value (MB) as the index, the interaction during the preparation of activated carbon were explored by Plackett-Burman design, the steepest climbing test, and the center composite design method.The results showed that the three most important factors obtained by Plackett-Burman design were immersion ratio, activation temperature, and activation time.The best center region was determined through the steepest climbing test.The optimal process conditions obtained by the center composite design (CCD) and response surface analysis (RSM) were impregnation ratio 3:1(g:g), activation temperature 563℃, and activation time 2.75 h. The verification experiment was performed under the above optimized process of 60% phosphoric acid mass fraction, 12 h immersion time, 90℃ immersion temperature. The pore size of the lignin-based activated carbon was mainly concentrated at 2-10 nm, the BET specific surface area was 1 436 m2/g, total pore volume was 1.041 cm3/g, the micropore pore volume was 0.385 6 cm3/g and the methylene blue adsorption value (MB)was 240 mg/g.
A novel soybean protein/polyacrylamide (SPI/PAAm) composite hydrogel was synthesized, in which soybean protein (SPI) and acrylamide (AAm) were used as raw materials, ammonium persulfate (APS) was used as the initiator, N, N'-methylenebisacrylamide (MBAA) was used as the covalent crosslinker, CaCl2 was used as the ionic crosslinker and N, N, N', N'-tetramethylethylenediamine (TEMED) was used as the accelerator. The structure and mechanical properties of the obtained hydrogels were analyzed, and the mechanical mechanism was then investigated. The results suggest that the obtained hydrogel had a double-network structure, including ionically-crosslinked soybean protein network and covalently-crosslinked polyacrylamide network. For the double-network hydrogel, the ionically-crosslinked network dispersed the applied stress and dissipated the energy, and the covalently-crosslinked network contributed to the shape retention. The synergistic effect resulting fromdouble networks endowed the hydrogel with high elasticity, high compressibility and fatigue resistance.The morphology analysis revealed that the obtained hydrogel showed a uniform cell structure, and the soybean protein was uniformly distributed within the hydrogel. The mechanical analysis indicated that the obtained hydrogel exhibited high compression-resilience property and elasticity, which could rapidly recover to its original shape upon 80% compressive strain without structural collapse or damage during 10 successive uniaxial compression cycles. More encouragingly, the obtained hydrogel possessed outstanding toughness and fatigue resistance, which could remain shape intact after undergoing 100 compression cycles at 20%, 50% and 80% strain, respectively.After 100 compression cycles at 20%, 50% and 80% strain, the corresponding stress remaining rates were 90%, 95% and 104%, the corresponding plastic deformation rates were 3.1%, 5.9%and 8.4%, and all the energy loss coefficients were below 0.3.
The pericarp of Sapindus mukorossi was extracted by water fermentation extract and ethanol extract and two kinds of extracts were obtained, with the comparative analysis of the chemical composition of two methods.The results showed that the purity of total saponins in water fermentation extract(WFE) (80.23%) was higher than that of ethanol extract(EE)(75.50%). Based on HPLC-DAD/MS, a total of 13 saponins were identified including 6 kinds of sesquiterpene glycosides and 7 kinds of triterpenoid saponins.WFE and EE both contained 12 saponins, of which triterpenoid saponins accounted for 66.07% and 80.39%, respectively. The MIC and MBC were used to compare in vitro antifungal activities. It was found that the WFE and EE all had significant antifungal activities, the MIC values were 62.50 and 31.25 mg/L and the MBC values were 250 and 125 mg/L, respectively. A mouse model of vulvovaginal candidiasis(VVC)was established to examine in vivo inhibitory effects. Compared with the negative group, the WFE significantly reduced (P < 0.05) the fungal burden and inflammatory factor (IL-6, IL-8). Both WFE and EE could improve VVC histopathology (P < 0.05). Therefore, S.mukorossi pericarp extracts had antifungal activity against Candida albicans in vitro and in vivo, and the treatment effect of the WFE was better.
Cellulose microfibril (CMF) was prepared from bleached softwood pulp by beating-high pressure homogenization process. The change of pulp fiber properties in beating process and the effects of homogenization process on the morphology and scale of CMF were studied. The results indicated that the beating process could effectively reduce the length of fiber and promote fiber microfibrization. The fibers with the Canadian standard freeness (CSF) of 0-800 mL and the length of 0.43-2.3 mm could be obtained by controlling the beating time 0-240 min. With the increase of homogenization passes, pressure and fiber mass concentration in homogenization process, the mechanical force strengthened, the microfibrization increased, the width of CMF decreased, and its width distribution tended to be concentrated. The multi-scale CMF with width from 406 nm to 134 nm could be prepared by controlling could the changes of homogenization passes (1-20 times), pressure (50-110 MPa) and fiber mass fraction(0.1%-0.5%). The beating-high pressure homogenization process could be used for environmentally friendly preparation of multi-scale CMF.
The cotton linters was used as raw materials to prepare water-soluble cellulose acetate (WSCA) with high degree of polymerization (Dp=650-680), by high mechanical strength and low degree of substitution novel one-step method. Subsequently, the WSCA solution and chitosan (CS) solution were mixed with different mass ratios to prepare the WSCA/CS composite films. The properties of the composite films were analyzed by SEM, TG, FT-IR, XRD, and tensile tests, and the effects of different mass ratios of WSCA and CS on the microstructure and properties of the composite film were discussed. The results showed that WSCA and CS with different mass ratios could be well dissolved in acetic acid solution and mixed evenly. As the ratio of WSCA increased, the WSCA/CS composite films presented a nacre-like layered microstructure, the nacre-like layered microstructure significantly improved the mechanical properties of the composite film. When m(WSCA):m(CS) was 1:1, the tensile strength of the composite film reached 126.5 MPa and the tensile strain at break was 7.3%, the thermal stability of the composite film was the best, and the maximum thermal weight loss rate temperature was 300 ℃.
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.
In order to investigate the separation characteristics of typical oxygenate components of biomass pyrolysis oil in both macro- and micro-level, a series of molecular distillation experiments were conducted under different evaporation temperature and operation pressure using cotton stalk pyrolysis oil as raw material. It showed that the distilled fractions had higher H/C molar ratios and contained higher oxygen content than the residual fractions, while the residual fractions contained higher carbon contents with higher heating value and their H/C molar ratios was close to 1. The separation factor(αi, n) was defined based on previous study and was used to evaluate the separation characteristics of typical compounds in micro-level. It showed that compounds with light molecular weights such as acetic acid, 1, 1-dimethoxy-propane, tetrahydro-2, 5-dimethoxy-furan were very easy to be distilled under all experiment conditions, while the distillation of 3-methyl-1, 2-cyclopentanedione was highly affected by the temperature and pressure in the experiment.It also indicated that monophenol compounds such as guaiacol, syringol and phenol could be distilled more easily than other compounds with large molecular weight, among which guaiacol was the easiest one to be distilled under 1 500 Pa and the phenol was less affected by temperature changes. It was much harder to distill diphenol than monophenol, among them, benzenediol showed comparatively poor distillation characteristics under the conditions of 2 500 Pa/50 ℃ especially. However, further lower the operation pressure could facilitate the evaporation of benzenediol largely. The changes of evaporation temperature and operation pressure had less effect on distillation of long-chain esters and carbohydrates than other compounds with large molecular weight.
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 activated carbon derived biomass waste corncob was investigated for the adsorption of antibiotic ciprofloxacin(CIP) from aqueous solution.The Box-Behnken design(BBD) of response surface methodology was used to optimize the operating conditions, the optimum adsorption conditions were found to be adsorption time of 537 min, adsorbent dosage of 0.46 g/L and pH 4.92. The results showed that the equilibrium adsorption amount of ciprofloxacin increased with the increase of temperature, and the adsorption equilibrium data were found to fit the Redlich-Peterson model and Sips model well. The thermodynamic parameters revealed the adsorption process of CIP on activated carbon was a spontaneous, endothermic and increasing entropy process.The Elovich model could perfectly describe the adsorption process of ciprofloxacin on activated carbon.At 298 K, the maximum adsorption capacity of ciprofloxacin was 238.01 mg/g, indicating that the corncob-based activated carbon was a promising adsorbent for the removal of ciprofloxacin from aqueous solution.
Based on the dissolution mechanism of cellulose macromolecules in alkali/urea system, self-bonding granular activated carbon was prepared with Chinese fir as raw material. The effects of different activation temperature, alkali/urea ratio and freezing conditions on the abrasion resistance and adsorption performance of granular activated carbon were discussed. The results showed that as the activation temperature increased the abrasion resistance and adsorption performance of activated carbon increased. Under the combination effect of alkali and urea, freezing process was beneficial to promote the development of activated carbon pore structure and improve the adsorption performance. Under the optimal conditions of the activation temperature 900℃, the alkali/urea mass ratio 14:36 and freezing time for 12 h, the abrasion resistance, iodine adsorption value, methylene blue adsorption value, specific surface area, total pore volume and average pore diameter of granular activated carbon were 99.12%, 1 204 mg/g, 232 mg/g, 1 365 m2/g, 0.86 cm3/g, and 2.46 nm.