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30 July 2020, Volume 54 Issue 4 Previous Issue   
Research Report
Preparation and Characterization of Activated Carbon from Coffee Grounds and Its Adsorption Mechanism for Cr(Ⅵ)
REN Jie, WAN Li, CHEN Nanwei, YANG Fan, SUN Shuiyu, REN Suizhou
2020, 54 (4):  1-8.  doi: 10.3969/j.issn.1673-5854.2020.04.001
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The preparation conditions of activated carbon from coffee grounds, including activation temperature, activation time and impregnation ratio, were studied by using the response surface methodology with iodine adsorption value as evaluation index. And the effects of adsorption time, initial pH value and temperature on the Cr(Ⅵ) removal by the obtained activated carbon were investigated. In addition, the kinetic data were fitted by pseudo-first-order equation, pseudo-second-order equation and infra-particle diffusion model, and the equilibrium data was analyzed by using Langmuir and Freundlich isotherm models. The experimental results showed that the activated carbon had the best performance under the optimum conditions of activation time 1 h, activation temperature 498℃ and impregnation ratio 1.72. Under these conditions, the yield of activated carbon was 30.4%, and the iodine adsorption value got up to (799±16) mg/g,the relative surface area could reach 1 006 m2/g, the total pore volume was 0.799 cm3/g, the t-Plot micropore volume was 0.051 cm3/g and the average pore size was 3.088 nm. The adsorption data fitted Langmuir isotherm model. Higher temperature and lower pH could promote the adsorption of Cr(Ⅵ) on activated carbon. The adsorption of Cr(Ⅵ) on activated carbon was divided into three stages:fast adsorption stage, slow adsorption stage and adsorption equilibrium stage, the total adsorption of 79% was completed in 10 min, the adsorption process could reach equilibrium in 360 min, and the pseudo-second-order equation generated the best agreement with the experimental data for the adsorption systems. The results showed that the adsorption of Cr(Ⅵ) on the obtained activated carbon was chemical adsorption with monomolecular layer.
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Deacidification Effect of Catalytic Esterification by Ionic Liquid on High Acid Value Oil
LI Huiwen, YANG Lingmei, LYU Pengmei, WANG Zhongming, MIAO Changlin, YUAN Zhenhong
2020, 54 (4):  9-15.  doi: 10.3969/j.issn.1673-5854.2020.04.002
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Using a self-made 1-propylsulfonic acid-3-methylimidazolium-p-toluenesulfonic acid ionic liquid([MIMPS] [C7H7O3S]) as catalyst, the esterification and deacidification of acidified oil with high acid value was carried out with self-designed equipment as reaction device. The effects of amount of methanol, amount of catalyst, reaction temperature, reaction time on the conversion of acidified oil and acid value of pre-esterified oil were investigated, and then the recyclability of catalyst was studied. The infrared spectrum analysis results showed that the synthesized ionic liquid accorded with its structural characteristics. The ionic liquid had good thermal stability under 200℃. The optimum process conditions determined by single factor and orthogonal tests were as follows:acidified oil 50 g, methanol 0.99 mL/min, catalyst dosage 2.5%, reaction time 3 hours, reaction temperature 105℃. Under these conditions, the conversion rate could reach 98.42%, and the acid value changed from 120 mg/g to 1.9 mg/g. After esterification, the acid value of the acidified oil met the requirement of the acid value for preparing biodiesel (less than 4 mg/g). As the ionic liquid catalyst was reused for 9 times, the conversion rate remained above 75%, indicating that[MIMPS] [C7H7O3S] ionic liquid catalyst had good catalytic activity and good stability for deacidification and esterification of acidified oil with high acid value.
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Preparation and Properties of Herba Epimedii Dregs Fungus Chaff Composite Super Absorbent Resin
ZHU Anxiang, DENG Tingfei, PAN Xiong, TIAN Yan, YANG Xiaosheng
2020, 54 (4):  16-22.  doi: 10.3969/j.issn.1673-5854.2020.04.003
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Using the dregs of Herba Epimedii as raw materials, the cultivation of edible fungi Pleurotus ostreatus was conducted to obtain medicinal fungus chaff; and then using the residues of medicinal residues as raw materials, acrylic acid(AA) as monomer, N,N'-methylenebisacrylamide(MBA) as cross-linking agent, ammonium persulfate(APS) as initiator, sodium sulfite(SBS) as co-initiator, the aqueous solution polymerization method was used to prepare the dregs fungus chaff-based composite superabsorbent resin(SAP). The effect of preparation conditions on water absorption was discussed. The best process conditions were 1.50 g fungus chaff, 6.00 g AA, neutralization degree of AA 70%, 0.090 g APS, 0.030 g SBS, and 0.010 5 g MBA. And on this basis, the untreated medicinal dregs was used to prepare superabsorbent resin for grafting control. The results showed that the water absorption rate of the resin formed by the fungus chaff to the filtered water and physiological saline solution under the optimal process conditions were 1 234.96 and 71.11 g/g, and much higher than the superabsorbent resin obtained by graft copolymerization of the original dregs, and it had good water retention performance with the water retention rate of 168 h 22.59%. FT-IR was used to characterize its structure, proving that acrylic acid was successfully grafted onto mycelium; the surface was observed as a rough porous structure by scanning electron microscopy.
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Dissolving Effect of Steam Exploded Corn Stalk on Phosphate Rock Powder and Influence of Its Residual on Wheat Growth
LIU Feifei, WANG Lan, LI Zuohu, CHEN Hongzhang
2020, 54 (4):  23-29.  doi: 10.3969/j.issn.1673-5854.2020.04.004
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In order to explore the dissolving effect of biomass on phosphate rock powder, steam explosion was used to release organic acid from corn stalk(CS) to dissolve phosphate rock powder(PRP) under high temperature and hydrothermal conditions, at the same time, phosphorus-containing humic acid was prepared. The process of dissolving phosphate rock powder by steam exploded corn stalk(SECS) was explored and the optimal conditions were determined. The structures and properties were investigated by Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM) and X-ray fluorescence spectroscopy(XRF). The results showed that under the conditions of temperature 170℃, 15 g steam exploded corn stalk, 1 g phosphate rock powder, 75 mL water, adding 10% calcium chloride, reaction for 3 h, the amount of dissolved phosphorus was 1.46 mg/g(based on the mass of stalk). The addition of sodium bisulfate could lower the pH value of the system to below 2, and the amount of dissolved phosphorus could reach 13.26 mg/g. Under high temperature and hydrothermal conditions, partial humification of stalks could be directly used as fertilizer. After adding 0.2% humic acid, the plant height, root length, chlorophyll content and relative conductivity of wheat were significantly higher than those of the control group.
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Preparation and Properties of Bacteriostatic Chitosan/PVA/Chitosan Oligosaccharide Nanofibrous Membranes
LIU Yongxu, ZHANG Dawei
2020, 54 (4):  30-36.  doi: 10.3969/j.issn.1673-5854.2020.04.005
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Chitosan(CS)/polyvinyl alcohol(PVA)/chitosan oligosaccharide(CHOS) nanofibrous membrane was prepared by electrospinning. The morphology, structure, bacteriostasis, hydrophilicity and solubility of the membrane were studied. Scanning electron microscope(SEM) observation showed that CS/PVA/CHOS nanofibrous membrane had uniform and dense micro morphology. FT-IR test showed that CHOS was dispersed in CS/PVA/CHOS nanofibrous membrane in the form of physical mixing. XRD test showed that the addition of CHOS changed the crystallinity of the nanofibrous membrane and promoted the compatibility between components. Water contact angle test showed that the nanofibrous membrane had good hydrophilicity. As the mass ratio of CS, PVA and CHOS was 20:80:10, the water contact angle of CS/PVA/CHOS nanofibrous membrane decreased from 59.8° to 37.5° compared with that of CS/PVA nanofibrous membrane with the mass ratio of CS and PVA 20:80. Bacteriostatic test and solubility test showed that CS/PVA/CHOS nanofibrous membrane with mass ratio of CS, PVA and CHOS 20:80:10 were better than those of CS/PVA nanofibrous membrane without CHOS, the bacteriostasis and solubility increased 38.9% and 38.6%, respectively.
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Novel Demineralization Technology of Phosphate-activated Carbon
XU Ruting, XU Wei, LU Xincheng, SUN Kang
2020, 54 (4):  37-41.  doi: 10.3969/j.issn.1673-5854.2020.04.006
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The solubilities in acid and water of the polyphosphate obtained from phosphate at different temperatures were determined. The results showed that the solubility of polymeric phosphate decreased with the temperature increase; as the preparation temperature increased from 350℃ to 650℃, the water solubility and acid solubility decreased from 98.71% and 98.93% to 73.12% and 74.80%, respectively. Compared with the conventional water elution process, the effects of acid pickling, heating, oxidant HClO and centrifugal process on the ash content and the adsorption capacity of commercial phosphate-activated carbon were studied. The specific surface area of activated carbon were determined. The results showed that the ash content of activated carbon reduced from 6.24% to 1.49% when the samples were washed twice by HCl and oxidant HClO and then washed three times by water in 80℃ with centrifugal dehydration process compared the sample of water washing. And the specific surface area, pore diameter, pore volume, iodine adsorption value, methylene blue adsorption value and caramel decolorization were 1 503 m2/g, 3.656 nm, 1.361 cm3/g, 975 mg/g, 277.5 mg/g, 110%, which were larger than those of the water washed sample. Therefore, low-ash phosphate-activated carbon could be prepared at low temperature and by using the above demineralization process.
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Optimization of Microwave Assisted Pyrolysis of Coconut Clothes by Response Surface Method and Analysis of Liquid Product Composition
DAI Qiqi, WEI Xiaocui, TANG Hongbiao, LI Jin, WANG Jinjing
2020, 54 (4):  42-48.  doi: 10.3969/j.issn.1673-5854.2020.04.007
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The Box-Behnken experimental design was used to optimize the microwave pyrolysis process of the coconut clothes by response surface method (RSM). The effects of microwave pyrolysis temperature, nitrogen flow rate, heating rate and pyrolysis time on liquid yield were investigated. The results showed that the regression equation model fitted well and was significant. The influence order of various factors on liquid product yield was microwave pyrolysis temperature > nitrogen flow rate > pyrolysis time > heating rate. The optimum conditions were temperature 550℃, nitrogen flow rate 80 mL/min, heating rate 20℃/min and pyrolysis time 20 min. According to this process, the obtained yield of liquid product value was 38.28%. The analyses of properties and composition of liquid product showed that the water content in the liquid product was 14.32%, the pH value was 3.78, and the maximum heating value under the best pyrolysis conditions was 24.61 MJ/kg.By GC-MS analysis of bio-oil, under the optimal conditions, the liquid product was composed of phenols, aldehydes, acids, ketones and so on, and their contents were 84.35%, 6.01%, 3.37%, 2.05%. The phenols included phenol(33.51%), p-cresol(9.71%), 2-methoxyphenol(10.99%) and 4-ethyl-2-methoxyphenol(5.57%).
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Status and Analysis of Nanocellulose Technology Based on Patents
SHANG Weijiao, WANG Lu
2020, 54 (4):  49-56.  doi: 10.3969/j.issn.1673-5854.2020.04.008
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PatSnap was used to collect domestic and foreign patent data of nanocellulose, and then patent publication trends, countries of patent assignees, main assignees, highly cited patents, technical areas and technological evolution paths were analyzed by patent analysis, patent maps and multiple main paths method. The results show that the technology of nanocellulose is in a fast developing stage and it is the hotspot of the world; USA, China, Japan, India and Finland are the leading countries; China has a large number of patents, but the impact needs to be improved, the assignees are mainly universities; the preparation of nanocellulose is key point and the application is wide.
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Review Comment
Research Progress in Nanocellulose Hydrophobic Modification and Applications
SUN Lin, LIU Huayu, LIU Kun, ZHANG Xiaoyi, XIE Hongxiang, ZHANG Rui, LI Haiming, SI Chuanling
2020, 54 (4):  57-66.  doi: 10.3969/j.issn.1673-5854.2020.04.009
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As a renewable nanomaterial, nanocellulose displays excellent performances and exhibits wide application potentials. However, nanocellulose has extremely strong hydrophilicity due to its abundant hydroxyl groups. Thus, the above characteristics not only seriously affect the performance of nanocellulose in terms of hydrophobicity, but also limit its applications in the field of composite materials to a certain extent. This article summarized the research advances of hydrophobic modification of nanocellulose in three aspects:physical adsorption, surface chemical modification(silylation, alkanoylation, esterification, etc.), and polymer graft copolymerization. Current wide applications of hydrophobic nanocellulose were also summarized in fields of packaging materials, papermaking, and water purification. At the end of this paper, the future development of hydrophobically modified nanocellulose was prospected, aiming to provide reference for the research and wide application of hydrophobic nanocellulose.
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