Camellia oleifera Abel shell, as a by-product produced during the processing of Camellia oleifera Abel, was usually discarded or burned. The resource utilization of C. oleifera shell can not only improve its own added value, but also solve the environmental pollution problems caused by it. Based on the existing research, this paper introduced the main functional components of C. oleifera shell and the utilization of C. oleifera shell in material, fertilizer and energy. C. oleifera shell contained tannins, tea saponins, flavones and polysaccharides and other substances, which made C. oleifera shell an ideal raw material for antibacterial, antioxidant, antiviral and other applications. In terms of materialization, the activated carbon adsorbent of C. oleifera shell showed good adsorption effect, but the capacitance material prepared from C. oleifera shell was low in conductivity, and the mechanical properties of wood-based composites were poor. In the aspect of fertilizer, the organic fertilizer and culture medium prepared from C. oleifera shell could obviously improve the soil, improve the quality of fertilizer and promote the growth of seedlings. In terms of energy utilization, the high lignin, hemicellulose and cellulose content made C. oleifera shell have certain advantages in direct combustion power generation, marsh gas production by anaerobic fermentation, bioethanol and bio-oil preparation, but there are some problems such as chloride corrode boiler, lignin is difficult to degrade, low bioethanol yield, low bio-oil yield and so on. In addition, the future utilization direction of C. oleifera shell was prospected. In the aspect of preparing carbon material, the C. oleifera shell need targeted carbonization for capacitor material. In the aspect of wood-based composites, it need to improve the structure and mechanical property. In the aspect functional components utilization, it need to develop high value-added deep processing products and expand production scale. In the aspect of energy, it need to solve the integration problem of biomass conversion process.
Biorefinery is an excellent strategy to deal with the energy crisis and environmental pollution in the new age. Based on biorefinery, low-value biomass resources can be converted into various value-added products. Furfural is one value-added platform chemical from biomass resources, which has important applications in energy, medicine, chemical, and other fields. The industrial production of furfural has come out for nearly one century and is relatively mature nowadays. However, there are still some issues remain to be solved in the industrial production. In order to solve these problems, efforts have been paid on exploring new technologies and progresses. In this paper, the characteristics of furfural were introduced firstly, and the present situation and problems of furfural industrial production technology are summarized, including corrosion of equipment caused by acid catalysts, difficulty in catalyst recycling, water pollution and so on. Then, the research status and problems of furfural preparation by hydrolysis and pyrolysis and the characteristic of the microwave-assisted technology were carefully reviewed. Finally, the future development direction of furfural preparation technology was prospected.
Corn straw based activated carbon was prepared from corn straw after formed and torrefied by H3PO4 activation and characterized by N2 adsorption, elemental analysis and FT-IR. The results showed that the optimal conditions were the impregnated ratio of 4∶1, the activation temperature of 400 ℃ and the activation time of 100 min. Under these conditions, the yield of activated carbon was 47.78% and the activated carbon showed excellent adsorption capacity with the iodine adsorption value of 864 mg/g, the methylene blue adsorption of 210 mg/g and the caramel decolorization of 100%. The specific surface area and the total volume of activated carbon reached 1 105 m2/g and 0.745 cm3/g, the micropore volume was 0.287 cm3/g, the mesopore volume was 0.354 cm3/g. Meanwhile, the distribution of pore was concentrated within 5 nm, accounting for 73.56%, and the average pore diameter is 2.697 nm. The FT-IR results showed that the crosslinking reaction was occured between H3PO4 and corn straw during octivation and the activated carbon lost some functional groups of corn straw.
Eucommia ulmoides gum(EUG) is a kind of natural polymer material with good biocompatibility, excellent rubber-plastic duality, and good mechanical properties, which has attracted much attention in the field of novel biomaterials in recent years. However, the poor elasticity and miscibility at room temperature have greatly limited its application in the field of functional materials. Therefore, the physical or chemical modification of EUG for broadening its range of applications has become the research hotspot. Combining with the structural characteristics of EUG, the common modification methods, formation mechanism and material properties of EUG by physical and chemical modification were firstly summarized, such as changing the hardness and elasticity of EUG by blending with other materials or epoxidation modification, vulcanization modification, etc. Then, the latest applications of EUG in green tire and road construction, shape memory and self-healing materials, anti-vibration and sound absorption, medical materials, and biodegradable composite are introduced, respectively. Finally, we envision that the EUG will play an increasingly important role in polymer science in future.
Based on the study of physical and chemical properties of co-hydrothermal carbonization products of municipal solid waste(MSW) and peanut shell(PS), thermogravimetry(TG) analysis was used to investigate the combustion characterstic and kinetics of co-carbonization products. The results indicated that the TG curves of co-carbonization products presented three weight loss peaks in the combustion, the lost degree of the second weightlessness peak was more than 50% of the total weightlessness. At the same co-carbonization temperature, with the increase of the proportion of peanut shells, combustion reactions were more thorough, TG curves were shifted to the high temperature side gradually. With the increase of heating rate, the ignition, the burnout temperature and the integrated combustion characteristic index improved. There existed synergistic interaction of co-carbonization products in the combustion process. With the increase of co-carbonization temperature(180-260℃), both fixed carbon content and combustion characteristic index S increased first and then decreased, the minimum ignition energy(Eαi) had an opposite trend. In this study, municipal solid waste were mixed with peanut shells at mass ratio of 5:5, under the conditions of co-hydrothermal carbonization temperature 220℃, the heating rate 40℃/min, co-carbonization product had the highest combustion characteristic index(5.727×10-6 min-2·℃-3) and the lowest ignition energy(89.55 kJ/mol).
The thermogravimetric analysis method was used to research the pyrolysis characteristics of chitin with KOH, and the effect of different impregnation ratios on the pyrolysis process was analyzed. The pyrolysis kinetic parameters were obtained by using the Coats-Redfern integral theory. The effect of KOH on the activation energy of the main pyrolysis process of chitin was investigated.The results of thermogravimetric showed that the addition of KOH changed the pyrolysis behavior of chitin, reduced the activation energy of pyrolysis accelerated the reaction rate and promoted the pyrolysis of chitin. Chitin could be fast pyrolysis with KOH at 140℃ and m(65%KOH): m(chitin)=2:1 or 3:1. The calculating results of pyrolysis kinetic parameters indicated that chitin pyrolysis with KOH was a complex reaction.
Woody oil is a traditional industrial oil in China, which has a wide range of industrial applications. It can be used as a source of high-quality edible vegetable oil, and also as a raw material for biodiesel production. It is widely used in feed additives and cosmetics industry.The content of C12-C18 unsaturated fatty acids in woody oil is high, which is easily absorbed by the human body. Different extraction technologies(pressing method, water enzymatic method, ultrasonic assisted method, leaching method, etc.) have little effect on the fatty acid composition and content of woody oilseeds. This article firstly briefly introduced the resources and applications of 7 woody oils, including rubber seed oil, walnut oil, coconut oil, Litsea cubeba kernel oil, peony seed oil, camellia seed oil and palm oil. The fatty acid composition of seven woody oils and their extraction and purification technology were summarized, and the extraction technologies of medium and long carbon chain unsaturated fatty acids in woody oils were emphatically introduced, and the applications of purified lauric acid, oleic acid, linoleic acid, and linolenic acid were reviewed and prospected.
In order to realize the direct application of olefin cross-metathesis on preparation of long-chain terminal olefin compounds from the crude fatty acid esters of vegetable oils, methyl oleate(MO) and methyl linoleate(ML) were used as raw materials to prepare long-chain terminal olefin compounds 1-decene(CM1), 1-heptene(CM2) and methyl 9-decenoate(CM3) through olefin cross-metathesis reaction. 4 typical Grubbs catalysts, 10 short carbon chain fluid substrates were chosen and different reaction temperature, time, catalyst dosage and moles ratio of substrate as the reaction conditions were investigated and contrasted. The results showed that the second-generation Hovey-Grubbs catalyst(C3) and the second-generation Grubbs catalyst(C2) were suitable catalysts for raw materials MO and ML, respectively. Eugenol was the most appropriate partner among the 10 substrates for producing aim products. The influences of temperature, time, catalyst dosage and ratio of substrate were investigated, the suitable reaction conditions were reaction temperature 0 ℃, time 20-60 min, catalyst dosage 0.5%-1% and the mole ratio of fatty acid ester to substrates 1∶10-1∶20, the highest conversion of MO and ML were 99%, and the yields of CM1, CM2 and CM3 were 80%, 92% and 73%, respectively.
Fast pyrolysis is one of the most promising methods for the efficient conversion and utilization of biomass. However, the target product, known as bio-oil, is difficult to utilize directly due to its high oxygen content and complex components. Fast pyrolysis of biomass catalyzed by alkaline earth metal oxides is able to remove the oxygen of the pyrolysis products in the form of CO2 and H2O, thereby improving the bio-oil quality. This review summarized the reaction mechanism (ketonization, aldol condensation, ring opening and side-chain scission) involved in the catalytic pyrolysis of biomass with the typical alkaline earth metal oxides-based catalysts. Also, the effects of catalysts (CaO, MgO, alkaline earth metal-based zeolites and activated carbons), raw biomass, pyrolysis temperature, catalyst amount, residence time, catalytic fast pyrolysis method and catalyst deactivation on the yield and quality of bio-oil were discussed. Finally, the application of biomass catalytic pyrolysis for producing high-quality bio-oil was prospected, which was expected to provide a theoretical basis for the utilization of biomass resources.
In recent years, the application field of superhydrophobic materials has become more and more extensive, and the requirements on mechanical strength, wear resistance, light transmissibility, reuse and other properties of super hydrophobic materials have become higher and higher, and the requirements on green environmental protection of raw materials have been increasing day by day. Biomass materials have many kinds and large volume, which occupy the do minant position of renewable resources. Cellulose, as the downstream fine products of biomass materials, has entered the field of vision of researchers with its advantages of green environmental protection, large reserves and flexible application. This paper briefly indicates the development history, characteristic, and application of superhydrophobic materials and cellulose, the application of superhydrophobic modification methods such as hydrothermal method, chemical deposition method, atom transfer radical polymerization and sol-gel method (cellulose/SiO2 super-hydrophobic materials and cellulose aerogel) in the preparation of cellulose based superhydrophobic materials was emphatically analyzed. Finally, the future development of cellulosic superhydrophobic materials was prospected.
In order to understand the overall situation of tea saponin research at home and abroad, and explore the hot issues and research trends, the annual publications, subjects involved, funding status, countries researched and institutes, lead author, quantity of master and doctoral dissertations, source journals of the research literatures of tea saponin, which were retrieved from the Web of Science and CNKI Chinese journal database from 1990 to 2019, were analyzed by using bibliometric analysis and CiteSpace keyword co-occurrence network analysis method. According to the result, the researches on tea saponin have been in the stage of rapid development since 2004, and the total quantity of the literatures and citations showed a year-by-year growth trend on the whole. The researches on tea saponin were mainly funded by national funds, and among 34 provincial administrative regions, more financial support was granted to Zhejiang and Hunan province. Globally, the research on tea saponin was mainly concentrated in China, followed by Japan and the USA. South China Agricultural University was the institution publishing the largest number of Chinese papers, and Zhejiang University was the institution publishing the largest number of SCI papers; YOSHIKAWA M of Kyoto Pharmaceutical University published the largest number of SCI papers. Currently, the hot issues of the researches on tea saponin mainly concentrated on in vitro pharmacological activity (antioxidant activity), rumen fermentation, methanogenesis and other directions. Besides, although constantly innovating and optimizing the methods of extracting tea saponin was not the research front, a lot of science researchers have constantly focused on it.
Tobacco in Sichuan, Guizhou, and Fujian was selected as raw materials, and the essential oil of tobacco was extracted by distillation in water. Gas chromatography-mass spectrometry(GC-MS) was used to analyze the composition and content of tobacco essential oil from different production areas, and the influences of different production areas on the yield and composition of the product were compared. The results showed that the average yields of tobacco from Fujian, Sichuan, and Guizhou were 0.139 1%, 0.085 1%, and 0.107 5%, respectively, and the corresponding contents of neophytadiene were 39.86%, 36.12%, and 44.88%, respectively. According to the comparison analysis, the tobacco produced in Fujian had the highest oil yield and moderate characteristic aroma; the tobacco essential oil produced in Guizhou had moderate oil yield, prominent tobacco aroma, and obvious licorice aroma; the tobacco essential oil produced in Sichuan had the highest oil yield, and weaker aroma.
Using natural and renewable plant oils as raw materials to prepare pressure-sensitive adhesives is an effective way to solve the current resource shortage and environmental problems of petroleum-based pressure-sensitive adhesives, it is also one of the hotspots in academic research and application development. The author reviewed the research progress of plant oil-based pressure-sensitive adhesives by domestic and foreign researchers in recent years. And the adhesives were classified according to the types of plant oil-based polymers (epoxy resin, acrylic resin, fatty acid derivatives, polyester and polyurethane, etc.), and the design ideas and modification methods of these research were emphatically summarized. On this basis, the development of new plant oil monomer structure and copolymerization with functional monomer were discussed, so as to provide a feasible theory and reference for the design and development of new bio-based pressure sensitive adhesive materials.
With the continuous improvement of the concept of green synthesis, transition metal catalysts with high catalytic activity, stability and low price replacing strong oxidizers and precious metal catalysts to catalyze the oxidation of 5-hydroxymethyl furfural(HMF) to prepare fine chemicals gradually become the focus of the researchers. This article reviewed recent researches on the use of cheap transition metal-based catalysts to catalyze the oxidation of 5-hydroxymethylfurfural(HMF) to 2, 5-furandicarbaldehyde(FDCA). The latest research in this field was described, with emphasis on introducing. The application of manganese-based, copper-based, iron/cobalt-based, nickel-based and other catalytic systems, such as manganese-based metal oxide, CuCl2 catalytic system, Fe3O4-CoOx magnetic catalyst, etc, in the HMF oxidation reaction were discussed. In addition, on the basis of the introduction of the above-mentioned catalysts, the development prospects of cheap transition metal-based catalysts catalyzed by HMF oxidation to prepare FDCA were also prospected.
The catalytic characteristics of metal ions for glucose isomerization and dehydration were investigated with metal chloride as catalyst. The influences of metal ion category, content and temperature on reaction process were studied. The reaction kinetic model was applied to correlate experimental data to analyze catalytic characteristics quantitatively. The process of glucose to HMF was a tandem reaction, and the kinetic model based on this mechanism could simulate the reaction accurately. Ni2+, Cr3+ and Sn4+ possessed good catalytic activity for glucose conversion, among which the catalyst activity of Sn4+ was the highest, and that of Ni2+ was the lowest. The kinetic constant of side reaction of Sn4+ was about 20 times of that of Ni2+. For Ni2+, reaction rate of glucose isomerization and side reaction increased, yet the catalytic activity for fructose dehydration to HMF was negligible with the increasing of Ni2+ content. Increasing of Cr3+ could enhance reaction rate of glucose isomerization significantly, and almost had no effect on other reactions. With the increasing of Sn4+ content, reaction rate of all steps increased, yet the intensity of side reaction would decrease. The influence of temperature on reaction constants followed the Arrhenius model. Higher temperature was beneficial to the side reaction, fructose dehydration and glucose isomerization respectively, when Ni2+, Cr3+ and Sn4+ were used, respectively.
Biomass gasification, heat supply and power generation industry is an efficient and comprehensive utilization of processing residues of forestry resources. The annual amount of forestry processing residues in China is about 210 million tons. The heat supply and power generation using renewable forest resources would improve the energy structure in our country, strengthen energy security, enhance the level of energy conservation and emissions reduction, promote the construction of new socialist countryside and sustainable development of forestry. However, several issues generally exist during the development of biomass gasification, heat supply and power generation industry, such as difficult collection, storage and transport of raw materials, poor automation and intelligent level of manufacturing process, immature standardized production technology, and lack of high-value and comprehensive utilization technology. So several suggestions were proposed, including strengthening the construction of forestry characteristic resource base, innovation of distributed industry development mode, breakthrough on the bottleneck technical problems, strict examination and approval of market access, intensive industry standard and government management, and improved policy support, in order to establish an industry system, including stable raw material supply, green manufacturing of high quality gas and efficient application of biochar. Moreover, the forestry residues annually utilized in gasification industry will be more than 5 million tons of standard coal, and the total output value will reach 10 billion yuan per year until 2035.
High-grade biofuels were produced from coconut oil through liquid phase cracking(LPC) and gas phase catalytic cracking(GPCC). With LPC of coconut oil, the maximum biofuel yield reached 76.5% under the pyrolysis temperature of 450 ℃, intake rate of 30 mL/min and reaction time of 40 min. However, the acid value of biofuel was above 100 mg/g. Thus the GPCC processing craft of pyrolysis liquid which was one of the cracking products was constructed with the CaO/bentonit as combined catalyst to reduce the acid value. The results showed that the maximum yield rate of biofuel reached 69.5% under the pyrolysis temperature of 400 ℃ and CaO dosage of 15% in the combined catalyst, and the acid value of the biofuel was 26.8 mg/g. Meanwhile, the minimum acid value of biofuel was 2.8 mg/g under the pyrolysis temperature of 450 ℃ and CaO dosage of 30% in the combined catalyst, and the yield of biofuel reached 64.1%. Through GC-MS analysis, it could be known that the major components in the liquid product via LPC were hydrocarbons, ketones, and acids, and their mass fractions were 32.6%, 24.2% and 43.3%, respectively. Compared with former, the hydrocarbons in GPCC liquid products increased by 23.3 percentage points, and the unfavorable acids and ketones decreased by 18.8 and 4.6 percentage points, respectively. The kinematic viscosity and oxygen content of biofuel obtained from the LPC of coconut oil decreased, while the acid value and low calorific value increased. Furthermore, the GPCC biofuel had lower acid value, lower oxygen content and higher calorific value than those of the LPC biofuel. As a whole, the GPCC biofuel had more similar properties with 0# diesel compared with the LPC biofuel.
Algal polysaccharide is a natural gel polysaccharide with great application potentials in emulsification and dispersion. Its hydrophilic and hydrophobic functional groups endow it with natural amphiphilicity, which could improve the interface compatibility between heterogeneous phases. Furthermore, the algal polysaccharide with a natural gel network structure could greatly improve the stability of the sol-gel system by effectively preventing the re-aggregation between the dispersed phases in the system. This paper introduced the chemical compositions, structures and properties of algal polysaccharides, including alginate, fucoidan, carrageenan, agar, ulvan, etc. Their amphiphilic structures were originated from the functional groups on sugar units including hydrophilic groups such as carboxyls and sulfates and hydrophobic groups such as methoxyls, acetyls and proteins. The effects of the amphiphilic structures on molecular configuration, surface activity and rheological properties of algal polysaccharides and further on their applications in emulsification and dispersion were summarized. At the same time, the researches on enhancing amphiphilic properties of algal polysaccharides by physical or chemical methods were introduced. The research progress of the applications of algal polysaccharide derivatives in emulsification and dispersion was summarized. Finally, the direction of enhancing the interfacial adsorption activity of algal polysaccharides was prospected.
The proportion of plant-based activated carbon used in the field of environmental protection is increasing year by year due to its characteristics such as wide sources, price moderate, short preparation cycle, mature process, large specific surface area, developed pore structure, low content of hybrid elements, and excellent thermal and chemical stability. The main components of plant are cellulose, hemicelluloses and lignin. In the present work, the effect of these three components on the pore formation of biochar and activated carbon was reviewed. In addition, the pore forming mechanism and characteristics of the formed pores of the physical activation, chemical activation (KOH activation, H3PO4 activation and ZnCl2 activation), catalytic activation and self-activation process were contrasted and summarized. Finally, the future research direction of plant-based activated carbon pore regulation was proposed based on the problems in previous research work.
The corn straw lignin was modified by demethylation/hydroxyethylation with sodium sulfite and glyoxal, to further improve the hydroxyl content and activity of lignin. The combined modification effect on lignin was characterized by Fourier transform infrared spectroscopic(FT-IR), thermogravimetric, differential scanning calorimetry(DSC) and acetylation titration. The results showed that the corn straw lignin modified by demethylation/hydroxyethylation had excellent activity. The total hydroxyl mass fraction of the modified lignin was 88.33% higher than that of the original lignin, and the phenolic hydroxyl group increased by 14.70%, which indicated that the reaction activity was significantly enhanced. Microscopic characterization by Fourier tansform infrared spectroscopy showed that the hydroxyl content of lignin was increased in many ways by combined modification, which had a significant effect on the increase of hydroxyl content. It was found by thermogravimetric and differential scanning calorimetry (DSC) analysis characterization that compared with the original lignin, the combined modified lignin(G-DL) degraded more thoroughly, with an exothermic peak at 77 ℃ and an exothermic value of 459.82 J/g. The activity of the reaction was higher than that of demethylated lignin(DL) and raw lignin.