Table of Content

30 March 2019, Volume 53 Issue 2 Previous Issue    Next Issue

Research Report

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Effect of Aluminum Hypophosphite Addition on Flame Retardancy of Alkali Lignin Based Polyurethane Foam Jiaxing ZHOU,Zhiming LIU,Xu LI 2019, 53 (2):  1-6.  doi: 10.3969/j.issn.1673-5854.2019.02.001 Abstract ( 515 )   HTML ( 904 )   PDF (4189KB) ( 899 )   Save Alkali lignin-based polyurethane foam(PUF/lignin) was prepared by substituting a part of the polyether polyol with the refined alkali lignin. The PUF/lignin/AHP material was prepared by adding aluminum hypophosphite(AHP) as flame retardant to alkali lignin-based polyurethane foam material. The flame retardant properties of PUF/lignin/AHP materials were tested by limiting oxygen index(LOI), and the thermal degradation behavior and char forming properties of the materials were investigated by thermogravimetric analysis(TG). Cone calorimetry(CONE) and scanning electron microscopy(SEM) were used to study the combustion behavior of PUF/lignin/AHP materials and the surface morphology of char residue. The test results showed that when the addition amount of alkali lignin was 5% of polyether polyol and the amount of AHP was 30%, the LOI value of PUF/5%lignin/30% AHP material reached 25.6%, and the thermal decomposition rate and total heat release of the material were lowered, and the char formation of the material was promoted. When AHP was decomposed by heat, the generated PO radicals captured the hydroxyl radicals generated during the combustion of the material, thereby suppressed the combustion reaction. At the same time, aluminum phosphate and aluminum pyrophosphate were produced to form dense carbon layer barrier substance and energy transfer, which prevented the material from further burning and improved the flame retardancy of the material. Figures and Tables | References | Related Articles | Metrics

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Preparation and Characterization of Undecylenic Acid/Maleic Anhydride Copolymer Meiting WU,Yonghe ZHANG,Liwei JIN 2019, 53 (2):  7-12.  doi: 10.3969/j.issn.1673-5854.2019.02.002 Abstract ( 707 )   HTML ( 160 )   PDF (699KB) ( 1089 )   Save Undecylenic acid/maleic anhydride copolymer(UMA) was prepared by precipitation polymerization method with undecylenic acid(UA) and maleic anhydride(MAH) as raw materials, azobisisobutyronitrile(AIBN) as initiator. The influences of monomer ratio, initiator dosage, and reaction temperature on polymerization were studied. The copolymer was characterized by FT-IR, 13C NMR, DSC and the mass fraction of anhydride of copolymer was measured. The results of FT-IR and 13C NMR showed that the copolymerization of UA and MAH successfully proceeded under the experimental conditions. When the reaction temperature was 75 ℃, the dosage of AIBN was 0.75%, with the increase of the amount of MAH, the molecular weight of copolymer decreased, the conversion rate and anhydride content incresed first and then declined slightly. When n(UA):n(MAH) was 40:60, the conversion rate and mass fraction of anhydride reached the maximum, 61.78% and 20.05%, respectively, which was basically consistent with the change of glass transition temperature(Tg) of DSC curves. Increasing the initiator dosage and reaction temperature was beneficial to the copolymerization but the molecular weight decreased, so the appropriate reaction conditions could be selected according to the properties of the desired polymer. When the n(UA):n(MAH) was 40:60, the Tg reached the maximum, 71.98 ℃. Figures and Tables | References | Related Articles | Metrics

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Preparation of Cotton Stalk Based Activated Carbon by KOH Activation and Its Adsorption Capacity for Phenol Wastewater Wenying TAN,Xiaohong CHENG,Shuo LI,Yuxiang YANG 2019, 53 (2):  13-18.  doi: 10.3969/j.issn.1673-5854.2019.02.003 Abstract ( 632 )   HTML ( 488 )   PDF (658KB) ( 1181 )   Save The activated carbon, which was obtained with agricultural waste cotton stalk as raw material, was prepared by the activation of potassium hydroxide and used to adsorb phenol wastewater. The optimum preparation conditions for cotton stalk based activated carbon were carbonized cotton stalk, KOH as activator, mass ratio of KOH and carbonized cotton stalk (material ratio) 1.5:1, activation temperature 800 ℃, activation time 70 min. Under these conditions, the adsorption value of methylene blue was 342.33 mg/g, and the iodine adsorption value was 1 368.65 mg/g. The BET specific surface area was 1 735.94 m2/g, the total pore volume was 0.36 cm3/g, and the average pore size was 2.33 nm. The activated carbon was used to adsorb phenol wastewater. When the amount of activated carbon was 50 mg, the mass concentration of phenol was 60 mg/L, the volume of wasterwater was 50 mL, the pH value was 7 and the adsorption time was 2 h, the removal rate of phenol was up to 98%. The kinetic analysis of the adsorption process showed that the pseudo-second-order kinetic model could better describe the process of the activated carbon adsorption of phenol. Figures and Tables | References | Related Articles | Metrics

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Transcript and Gene Expression Analysis of Chlorococcum sp. GIEC-38 with High Lipid Productivity Jia FENG,Shunni ZHU,Jin XU,Zhongming WANG,Zhenhong YUAN 2019, 53 (2):  19-25.  doi: 10.3969/j.issn.1673-5854.2019.02.004 Abstract ( 499 )   HTML ( 87 )   PDF (457KB) ( 831 )   Save The transcript of Chlorococcum sp. GIEC-38 which exhibited high biomass and lipid yield was sequenced. 74 605 transcripts and 65 984 genes were obtained related to 344 metabolic pathways which were active in ribosome, protein, nucleotide, RNA, carbon fixation, photosynthesis, and lipid metabolism. The lipid content of Chlorococcum sp. GIEC-38 cultured without nitrogen reached up to over 50% and compared with the original strain, 868 genes of strain cultured without nitrogen significantly up-regulated and 1 157 genes significantly down-regulated which were distributed in 41 biological functions and 71 metabolic pathways. It was found that the expressions of synthetase catalyzed intermediate products synthesis which provided for lipid acid synthesis and the key enzymes in metabolic pathways related to lipid metabolism were up-regulated significantly. All those changes promoted lipid synthesis and increased the lipid content of GIEC-38. Figures and Tables | References | Related Articles | Metrics

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Preparation and Properties of Melt-spun Kraft Hardwood Lignin-based Activated Carbon Fibers Erqiang YIN,Shichao WANG,Hengxue XIANG,Zhe ZHOU,Meifang ZHU 2019, 53 (2):  26-34.  doi: 10.3969/j.issn.1673-5854.2019.02.005 Abstract ( 768 )   HTML ( 2941 )   PDF (2751KB) ( 922 )   Save Kraft hardwood lignin activated carbon fiber(HKL-ACF) was prepared from carbon fiber(HKL-CF) by water vapor activation using melt-spun kraft hardwood lignin(HKL) fiber as raw material. On this basis, the effects of water vapor activation on the chemical structure and morphology of activated carbon fibers were investigated by infrared spectrometer and scanning electron microscopy. And the effects of different activation time, activation temperature and water vapor flow rate on specific surface area, pore structure and microcrystalline structure of the carbon fiber were studied by automatic physical adsorption instrument, X-ray diffractometer and Raman spectrometer. The results showed that the chemical structure of carbon fiber was changed greatly after water vapor activation, and the contents of C—O and C＝C were increased. At the same time, the specific surface area increased with the increase of activation time, and increased firstly and then decreased with the increase of activation temperature and water vapor flow rate. With the increase of activation time and temperature, the grain size became smaller. The degree of graphitization of the fiber surface became larger with the increase of activation time. The maximum BET specific surface area of activated carbon fiber was 2 081.34 m2/g and the maximum pore volume was 1.60 cm3/g under the activation temperature of 800 ℃, activation time of 4 h, and water vapor flow rate of 1 mL/min. Figures and Tables | References | Related Articles | Metrics

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In Vitro Antioxidant and Antibacterial Activity of Ethanol Extract from Mulberry Leaves Xinyan GAO,Haiying WANG,Zhiming LIU 2019, 53 (2):  35-40.  doi: 10.3969/j.issn.1673-5854.2019.02.006 Abstract ( 784 )   HTML ( 529 )   PDF (519KB) ( 954 )   Save Dry mulberry leaves was extracted by soxhlet extraction to obtain ethanol extract of mulberry leaves. And the composition, antioxidant activity and antibacterial activity of the ethanol extract of mulberry leaves in vitro were measured. The results showed that the ethanol extract of mulberry leaves contained many organics, including esters(82.85%), alkanes(6.31%), aromatic hydrocarbons(1.62%) and alcohols(0.21%). There was a significant linear relationship between the total reducing power and the concentration of ethanol extracts from mulberry leaves, and the extracts had good scavenging capacities of DPPH free radicals and OH free radicals with the half inhibitory concentrations(IC50) of 73.07 and 104.52 mg/L, respectively. The ethanol extract of mulberry leaves had certain inhibitory effects on Bacillus subtilis, Staphylococcus aureus and Escherichia coli. Inhibitory effects were B. subtilis > S. aureus > E. coli, IC50 were 4.824, 6.806 and 14.382 g/L, respectively. The antioxidant and antibacterial activity of the ethanol extract of mulberry leaves increased with the increase of sample concentration. Figures and Tables | References | Related Articles | Metrics

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Pore Structure and Fractal Characteristics of Biochars From Different Straw Xiefeng YE,Xiaona YU,Hanjun ZHOU,Zhipeng LI,Xiaofan ZHANG 2019, 53 (2):  41-46.  doi: 10.3969/j.issn.1673-5854.2019.02.007 Abstract ( 1449 )   HTML ( 322505812 )   PDF (947KB) ( 2272 )   Save Based on the cryogenic nitrogen gas adsorption method, the pore characteristics of biochars made from farmland waste including rice straw, corn stalk and wheat straw were studied. The BET equation, BJH equation and t-plot method were used to caculate the specific surface area, pore size distribution and microporous parameters, and FHH model was used to obtain the fractal dimension(D) of pore. Results showed that different temperature and different materials all had larger effects on the pore characteristics of biochar. With the increase of pyrolysis temperature, the BET specific surface area and pore volume of rice-straw-biochar and wheat-straw-biochar increased firstly and then decreased, whereas, the porosity of corn-stalk-biochar always increased. It was concluded that the mesopores were the main type of pores in three kinds of biochars and the pores mainly consisted of the second pores. It was found that rice-straw-biochar, corn-stalk-biochar and wheat-straw-biochar all had good fractal characteristics, and the pore fractal dimensions were 2.545 4-2.669 3, 2.629 7-2.689 5 and 2.577 3-2.597 2, respectively, which reflected the complexity and heterogeneity of the biochar porosity. Both rice-straw-biochar and wheat-straw-biochar had higher fractal dimension at 500 ℃(2.669 3 and 2.597 2), but corn-stalk-biochar had higher fractal dimension at 700 ℃(2.689 5). Figures and Tables | References | Related Articles | Metrics

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Optimization of Preparation Process of Cellulose Nanocrystals Min DUAN,Tao LIN,Xuefeng YIN,Jing LI 2019, 53 (2):  47-53.  doi: 10.3969/j.issn.1673-5854.2019.02.008 Abstract ( 1069 )   HTML ( 2617 )   PDF (2017KB) ( 1024 )   Save Cellulose nanocrystals(CNC) were prepared from microcrystalline cellulose(MCC) by sulfuric acid hydrolysis. The effects of sulfuric acid mass fraction, reaction temperature and reaction time on the yield and average particle size of cellulose nanocrystals were studied by single factor method combined with orthogonal test. The performance of CNC was characterized by scanning electron microscopy(SEM), atomic force microscopy(AFM), X-ray diffractometer(XRD) and nano-laser particle size analyzer, and the mechanism of acid hydrolysis to prepare CNC was revealed. The results showed that the optimum process parameters of CNC preparation were sulfuric mass fraction 64%, reaction temperature 45 ℃ and reaction time 90 min. Under these conditions, the yield of CNC was 24.6% and the particle size was 204.8 nm. The CNC aqueous suspension was a kind of stable light blue colloidal state, and its microscopic morphology was relatively regular, which was short rod-shaped, with diameter of about 10-20 nm and length between 150-300 nm; XRD results showed that the crystal form of CNC was cellulose type Ⅰ, and the crystallinity was 80.2%. Figures and Tables | References | Related Articles | Metrics

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Optimization of Preparation Technology of Peanut Shell Based Activated Carbon by Response Surface Model Xueqin LI,Zhiwei WANG,Miao YANG,Tingzhou LEI,Haiyan XU,Xiaofeng HE 2019, 53 (2):  54-60.  doi: 10.3969/j.issn.1673-5854.2019.02.009 Abstract ( 576 )   HTML ( 273 )   PDF (3499KB) ( 899 )   Save The process conditions of wood-based activated carbon were optimized by using agriculture and forestry waste, peanut shell, as raw material, phosphoric acid as activator and sulfuric acid as auxiliary activator. The impacts of phosphoric acid concentration, impregnation ratio(volume-mass ratio of activator to peanut shell), activation time, activation temperature on the properties of activated carbon were investigated by using the response surface methodology. The results showed that through Box-Behnken test data, the P value of mathematical model of quadratic polynomial on the methylene blue adsorption value and iodine adsorption value was less than 0.000 1, the correct determination coefficients(R2) were 0.990 2 and 0.997 8, respectively, reached extremely significant level; and CV was less than 10%, the experiment had most high credibility and accuracy, and the regression equation was established. The optical process conditions of using phosphoric acid-sulfuric acid activation method to prepare peanut shell based activated carbon were peanut shell powder 1 g, phosphoric acid mass fraction 57.7%, impregnation ratio 2:1, activation time 117 min and activation temperature 550 ℃. Under the conditions, the methylene blue adsorption value was 147.2 mg/g, the iodine adsorption value was 1 022.03 mg/g, which was close to the predicted values and had good repeatability, the inner hole of the peanut shell base activated carbon was more developed, the larger methylene blue adsorption value and the relatively small iodine adsorption value maked the activated carbon have stronger adsorption capacity and desorption capacity, the study of preparation mechanism of peanut shell activated carbon had laid a solid foundation. Figures and Tables | References | Related Articles | Metrics

Review Comment

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Research Progress of Influence of Promoters on Performance of Nickel-based Catalyst for Biomass Tar Reforming Xuetao WANG,Xiaoxin SU 2019, 53 (2):  61-66.  doi: 10.3969/j.issn.1673-5854.2019.02.010 Abstract ( 548 )   HTML ( 401 )   PDF (556KB) ( 1064 )   Save This review discussed the influence of promoters in terms of catalyst performance, physical and chemical properties as well as deactivation characteristics of catalyst from the perspective of alkali and alkaline earth metals, transition metal and rare earth metal, respectively.After the addition of alkali metal components, the biomass pyrolysis reaction rate will increase significantly, the steam gasification reaction of biomass coke will be promoted, and the temperature required to achieve the maximum pyrolysis rate will also decrease, the pyrolysis products tend to be small molecular weight products. The transition metal has good catalytic activity to the catalytic cracking reforming of tar in the gasification process. Rare earth elements play an important role in catalytic reactions such as methanol steam reforming. The addition of Ce and Pr in nickel-based catalysts can improve methanol conversion, gas-producing components and H2 selectivity. Combined with the domestic and foreign research, it is found that Co, La and other metal promoters are conducive to improving the hydrogen production activity of nickel-based catalyst, while carbon deposition and active particles aggregation are the main causes of catalyst deactivation. Figures and Tables | References | Related Articles | Metrics