Preparation of Wheat Straw Nanocellulose by Acid Hydrolysis Assisted High Pressure Homogenization

QI Minghui,YI Tan,MO Qi,DENG Jingchun,ZHANG Jinlan,HUANG Lijie,HUANG Chongxing,LIU Yang,ZHAO Hui,WANG Shuangfei

2020,35(3):1-8

Nanocellulose of wheat straw was prepared in layers by means of acidolysis assisted high pressure homogenization. Subsequently， the layered wheat straw nanocellulose was characterized by Marvin nano-particle analyzer， transmission electron microscope， atomic force microscope， infrared spectrum， X-ray diffractometer and thermal stability analyzer. The nanocellulose prepared from the supernatant was the nanocellulose whisker， and the crystallinity increased from 48.61% of the wheat straw materials to 71.87%. The residual fiber solids of wheat straw after cellulose acidolysis were homogenized for 8 times under the condition of 150 MPa to obtain nanocellulose. The resulted particle size distribution was 100~200 nm， the diameter was about 15 nm， and the same nanocellulose whiskers with high crystallinity （Iβ） were obtained. The thermal stability of both nanocellulose wiskers decreased compared with the raw materials. The yield of nanocellulose prepared by this method was higher than that by the method of complete sulfuric acid hydrolysis， and the number of homogenization times was obviously reduced compared with that of complete mechanical homogenization.

[Abstract] [PDF]

Preparation and Characterization of Cellulose Nanocrystals from Bleached Bamboo Pulp Sheet

LIU Jianrong,ZHANG Zhenyu

2020,35(3):9-14

In order to obtain cellulose nanocrystals （NCC）， bamboo pulp was treated with sulfuric acid assisted by magnetic stirring and ultrasonic wave after alkali pretreatment. The solid-liquid ratio of bamboo pulp to sulfuric acid was 1∶31. Effects of sulfuric acid concentration， sulfuric acid assisted with magnetic stirring treatment time and reaction temperature on NCC were discussed. And the properties of NCC were characterized by SEM， AFM， XRD and TGA. The results showed that the particle size of NCC was small and the distribution of NCC was uniform， and the crystal structure of NCC was changed from cellulose II to cellulose IVII when the optimum preparation condition of NCC was concentration of sulfuric acid of 65%， the reaction temperature of 45℃ and the treatment time of 45 min. Compared with bamboo cellulose， the adsorption capacity， accessibility， and thermostability of NCC were improved.

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Preparation and Properties of Nacre-inspired MTM/PVA/ANF Composite Films by Different Methods

MA Qin,SI Lianmeng,LUO Zhirong,LU Zhaoqing

2020,35(3):15-20

MTM/PVA/ANF composite films with nacre-like structure were prepared by water evaporation induced self-assembly （A）， vacuum-assisted suction filtration （F） and their combination with centrifugal treatment （C）. The microstructure， thermostability， light transmittance， hydrophilicity， and mechanical properties of the composite films were characterized by SEM， AFM， TGA， UV spectrometry， dynamic contact angle and tensile tester. The results showed that the composite films obtained by different combinations of preparation methods （A， CA， F， CF） exhibit a distinct layered structure， and the transmittance， hydrophilicity and mechanical properties of the films were different. The composite film prepared by method F had higher light transmittance and better hydrophobic property； the composite film prepared by method CF had the best mechanical properties， and its tensile strength reached to 132.4 MPa， and the composite film prepared by method A had more excellent toughness and its elongation at break was as high as 11.3%.

[Abstract] [PDF]

Impact of Fiber Fractionation on the Yielding Properties of Bleached Spruce Pulp Fiber Suspensions

WANG Can,LI Jinlong,WANG Qi,SHAO Yuzheng,SHA Jiulong,WANG Shuangfei

2020,35(3):21-26

In order to study the influence of fiber fractionation on the yield stress of bleached spruce pulp fiber suspensions， the compressive and shear yield stresses of fiber suspension were measured by sedimentation and rheological methods， and their coupling correlation was also analyzed. The results showed that the gel crowding number of pulp samples before and after fractionated ranged from 26.1 to 37.8， and increased approximately linear with the fiber aspect ratio. Compressive and shear yield stresses of all suspensions of fiber fractionations increased exponentially as increasing of the crowding number. Moreover， Froude number decreased gradually with increasing crowding number， and finally approached a stable value.

[Abstract] [PDF]

Optimization of Fenton Oxidation Pretreatment of Poplar by Response Surface Methodology

LEI Shanshan,SHI Yan,ZHI Yamei,YIN Hao,YAO Lan

2020,35(3):27-33

In this study， on the basis of single factor experiment and response surface method， the optimum conditions for Fenton oxidation pretreatment of poplar for bioethanol production were obtained： H2O2/FeCl3=10%， pH value 2.5， FeCl3 concentration 50 mmol/L， and the yield of glucose under these conditions was 51.4%. Analysis by response surface showed that FeCl3 concentration had the most significant effect on the yield of glucose， H2O2/FeCl3 had the most significant effect on delignification ratio. Component analysis of pretreated poplar indicated that lignin was removed partly during Fenton oxidation pretreatment. But there was no correlation between lignin removal and cellulose conversion. Furthermore， the cellulose crystallinity and specific surface area of pretreated poplar were increased by 12.8% and 80.2%， respectively， compared with the control. The increased specific surface area is beneficial to the enzymatic degradation of cellulose， which is one of the mechanisms of improving enzymatic degradation of poplar with the help of Fenton oxidation pretreatment.

[Abstract] [PDF]

Study on Surface Oxidation of Pulp Fiber by MFC Loaded Iron Ion Catalysis based on Fenton Reaction

LIU Rongrong,LI Qun,DUAN Linjuan

2020,35(3):34-39

Iron ions were loaded on micro-fibrillated cellulose as a catalyst to perform Fenton oxidation pretreatment on the surface of softwood bleached kraft pulp （SWBK）. The distribution of hydroxyl radicals generated by Fenton reaction on the fibers was detected by laser scanning confocal microscopy （LSCM）. The adsorption of iron ion on the fibers was determined by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. The influence of Fenton oxidation pretreatment on fiber surface was evaluated through the average degree of polymerization （DP）， fiber morphology， the tensile index and tearing index of handsheets under the same PFI beating revolution. The results showed that the hydroxyl radicals generated by the decomposition of hydrogen peroxide during the oxidation pretreatment process were mainly occurred on the surface of the pulp fibers， which made them possible to oxidize the surface of the fibers. Compared with the pulp without Fenton pretreatment， the DP of Fenton surface-oxidated pulp only decreased by 4.9%. When the PFI beating revolution was about 8000 r， the tensile index and the tearing index of the sheet made with surface oxidation pretreated fibers were increased by about 20.9% and 25.7% respectively compared with the handsheet prepared with the original pulp.

[Abstract] [PDF]

Determination of 5-Hydroxymethylfurfural in Pre-hydrolysate of Eucalyptus by UPLC-PDA Method

QI Yungeng,MA Mingshuai,GUO Huaize,LI Haiming

2020,35(3):40-45

A method was developed to determine 5-hydroxymethylfurfural （5-HMF） in the pre-hydrolysate of Eucalyptus by Ultra Performance Liquid Chromatography-Photo-diode Array Detector （UPLC-PDA）. Without complicated pretreatment， different components in the samples were eluted and then separated with the mobile phase of acetonitrile/water （20/80，V/V） at flow rate of 0.2 mL/min， and then quantitatively detected with PDA detector at 283.55 nm. Detection limit， the correlation coefficient， relative standard deviation （RSD） and 5-HMF standard recovery rate of the determination method were 3.883 μg/L， 0.9998， 0.2% and 105.2%， respectively. The method developed had characteristics of simple sample preparation， fast determination and high accuracy. Finally， this method was used for fast determination of 5-HMF in the Eucalyptus pre-hydrolysate， which was beneficial to optimization of pre-hydrolysis conditions and utilization of pre-hydrolysate.

[Abstract] [PDF]

Discussion on SEM Sample Preparation and Imaging Techniques in Pulp and Paper Discipline

HUANG Yanbo,WANG Ruoyun

2020,35(3):46-52

Scanning election microscopy （SEM） preparation techniques for samples such as paper， pulp， powder （filler and auxiliaries） and film were introduced. The common problems in SEM experiment were also discussed. The authors suggested using carbon conductive adhesive tape， silver liquid conductive adhesive to enhance the conductivity of the sample surface. As for the sample of fiber cross-section， using ion beam cutting technology could effectively avoid sample deformation caused by mechanical cutting. Optimizing coating time and accelera-ting voltage could significantly avoid the imaging problems caused by charging effect， edge effect， and electron beam damage.

[Abstract] [PDF]

Application of Projection Pursuit Classification Model in Comprehensive Evaluation of Common Papermaking Materials

ZHAO Jingyuan,XIONG Zhixin,LIANG Long,FANG Guigan

2020,35(3):53-58

In this paper， the projection pursuit classification （PPC） and accelerated genetic algorithm （RAGA） based on real coding were combined and optimized multiple index parameters to convert high-dimensional data indexes into one-dimensional projection. Based on the RAGA-PPC model， the various papermaking raw materials were classified， and evaluated effectively. The conclusion demonstrated that eva-luation result of RAGA-PPC model was consistent with the actual category of the papermaking raw materials. Furtherly this method has more advantages in objectivity， reliability， accuracy and has practical application prospects.

[Abstract] [PDF]

Research on Online Monitoring and Evaluation Method of Energy Efficiency in Dryer Section of Paper Machine

CHEN Xiaobin,ZHENG Qifu,DONG Yunyuan,ZHAN Zhengfeng,LI Jigeng,CHEN Xueping,LIU Yuan

2020,35(3):59-64

Through the analysis of the energy consumption in dryer section of paper machine， the online monitoring and evaluation method of energy efficiency in dryer section was preliminarily explored. Four energy efficiency indexes for online monitoring in dryer section were put forward， which were specific steam consumption and heat efficiency of dryer section， specific power consumption of ventilation and heat recovery system， heat recovery efficiency of ventilation and heat recovery system， their calculation models were established simultaneously. Finally， based on the proposed indicators， current paper authors studied the energy efficiency evaluation method of dryer section. Therefore， the energy efficiency level of the dryer section could be evaluated in real time from two dimensions of energy efficiency benchmarking and energy efficiency rating.

[Abstract] [PDF]

Catalytic Ozonation Treatment of Papermaking Wastewater by Al2O3 Loaded with ZnO

ZHOU Lang

2020,35(3):65-69

A catalyst loading ZnO on Al2O3 for oxidative degradation of papermaking wastewater was prepared. The properties of the catalyst was characterized by XRD and SEM. The effects of initial pH value of papermaking wastewater， reaction time， and catalyst dosage on the treatment of papermaking wastewater were studied. In addition， the effect of the free radical trapping agent tert-butanol on the catalytic ozone treatment of wastewater was also characterized. The characterization results showed that the Al2O3@ZnO catalyst with good catalytic performance was successfully prepared. Under the conditions of pH value=11， catalyst dosage of 2.0 g/L， and reaction time of 60 min， the removal rate of chemical oxygen demand （COD） reached 84.6%. Furthermore， the removal rate of the catalytic ozonation method was significantly higher than that of the ozonation method alone. The kinetic degradation reaction of CODCr followed a quasi-first-order equation. The experimental results of tert-butanol showed that in the process of Al2O3@ZnO catalyst treating organic matter in papermaking wastewater， hydroxyl radical was the main factor in the degradation of organic matter in wastewater.

[Abstract] [PDF]

Research Progress in Preparation of Enzyme-mimic Solid Acid and Improvement of Cellulose Hydrolysis

JIN Shuyuan,CHENG Yi,LU Jie,WANG Haisong

2020,35(3):70-79

Traditional solid acid has been sought after as the advantage of no corrosion， easier to recover and reuse， etc. However， the traditional solid acids generally have the problem of poor affinity to cellulose and lower hydrolysis efficiency. In order to overcome the above-mentioned drawbacks， mimicking the cellulase hydrolysis mechanism， a cellulose binding group （CBD） was introduced to synthesize the enzyme-mimic solid acid which can improve the cellulose hydrolysis efficiency by forming hydrogen bonds between CBD and cellulose and oligosaccharide. In this review， the process and mechanism of hydrolysis of cellulose by enzyme-mimic solid acid were analyzed， and the preparation methods and hydrolysis effects of several commonly used imitation enzyme solid acids were summarized. Finally， some research trends in the future were also prospected to provide some valuable ideas for the hydrolysis of cellulose into glucose in a more green， simple， efficient and inexpensive way.

[Abstract] [PDF]

Research Progress of Aramid Nanofibers and Their Composite Materials

CHEN Jian,JIA Fengfeng,XIE Fan,YAO Cheng,WANG Yafang,LU Zhaoqing

2020,35(3):80-87

The recent progress of aramid nanofibers nanofabrication technology at home and abroad was reviewed. The mechanism and application advantages of aramid nanofibers obtained by alkali/dimethyl sulfoxide splitting approach were introduced emphatically. Afterthat， the research progress in application of aramid nanofibers in high strength & high toughness materials， filtration materials， transparent materials， battery materials， electromagnetic shielding materials， thermal insulation materials and electric heating materials were summarized. Finally， the research direction of aramid nanofibers in future was discussed and prospected.

[Abstract] [PDF]