Research Progress in Preparation of Oxidized Cellulose

Cellulose is the most abundant natural polymer material in the world.Cellulose is diffi-cult to dissolve because it contains a large number of inter molecular hydrogen bonds.Therefore,the modification of natural cellulose by chemical oxidation can expand its application field.The oxidation process of cellulose is focused on,the oxidation methods and research progress of cellulose are introduced,and further development direction of oxidized cellulose is prospected.

Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

The 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)oxidized cellulose film(TOCF)has been attempted to be used as a substrate in electronic and optoelectronic devices,but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication.In this study,TOCF was treated in different atmospheres(air,vacuum,and N2)and at different temperatures,and the properties were investigated.The results indicate that the optical properties are slightly affected by atmosphere and temperature;only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃.In contrast to the slight effects on the optical properties,cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃.Specifically,TOCF was exposed to air,followed by N2 and vacuum atmospheres.Additional Fourier transform infrared(FT-IR)and nuclear magnetic resonance(NMR)results showed that increasing the temperature had no significant effect on the structure of TOCF.Therefore,the annealing temperature should be controlled at a temperature of lower than 100℃and a vacuum atmosphere is preferred.

Unexpected Postoperative Paraplegia after Thoracotomy in Lung Cancer: Incidental Migration of Oxidized Regenerated Cellulose Used for Hemostasis of Intercostal Space Bleeding

Background: We experienced a very rare complication, that is, an unexpected postoperative paraplegia due to the incidental migration of oxidized regenerated cellulose used for hemostasis of intercostal space bleeding. Patients and Methods: The objective is to analyze the cause and to take measures against the very rare complication from an empirical analysis and the literature. For a 78-year-old male with suspected lung cancer in the right upper lobe (S1), a thoracotomy was performed. For hemostasis of the bleeding from the 5th intercostal thoracotomy space, we used and placed oxidized regenerated cellulose at the continuous oozing bleeding sites. On the 3rd postoperative day, paralysis beneath thoracic vertebrae level 6 was observed. Immediate computed-tomographic (CT) scanning and magnetic resonance imaging (MRI) displayed a 17 × 9 × 14 mm epidural hematoma in the spinal canal at level 5 of the thoracic vertebrae. An emergent laminectomy for the thoracic vertebra was performed to remove the oxidative cellulose and haematoma, and the compression was released. The paraplegia gradually began to recover and maintain a standing position. After 1 year from the event, the patient can walk by himself with a crutch. Results: The causes were that the oxidative cellulose materials were used for the intercostal bleeding at the open thoracotomy. The migration of the oxidative cellulose materials into the epidural space and into thoracic spinal canal through the intervertebral foramen, or gradual penetration of the oxidative cellulose materials into the spinal canal due to respiratory costal movement. As a measurement of prevention, the hemostat materials should be completely removed after finishing of the hemostasis. In the case of a difficult hemostasis, consultation of an orthopedist or neurosurgeon to perform the appropriate hemostasis in good cooperation is required. Conclusion: If postoperative paraplegia is suspected, immediate CT scanning and/or MRI examination would become powerful diagnostic procedures as soon as possible to start an interventional treatment.

Lightweight,Flexible Cellulose-Derived Carbon Aerogel@Reduced Graphene Oxide/PDMS Composites with Outstanding EMI Shielding Performances and Excellent Thermal Conductivities

In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required to attenuate electromagnetic wave energy.In this work,the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide(NaOH)/urea solution,and cellulose aerogels(CA)are prepared by gelation and freeze-drying.Then,the cellulose carbon aerogel@reduced graphene oxide aerogels(CCA@rGO)are prepared by vacuum impregnation,freeze-drying followed by thermal annealing,and finally,the CCA@rGO/polydimethylsiloxane(PDMS)EMI shielding composites are prepared by backfilling with PDMS.Owing to skin-core structure of CCA@rGO,the complete three-dimensional(3D)double-layer con-ductive network can be successfully constructed.When the loading of CCA@rGO is 3.05 wt%,CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness(EMI SE)of 51 dB,which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites(13 dB)with the same loading of fillers.At this time,the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability(T_(HRI) of 178.3℃)and good thermal conductivity coefficient(λ of 0.65 W m^(-1) K^(-1)).Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight,flexible EMI shielding composites.

Layer-by-Layer Assembled Bacterial Cellulose/Graphene Oxide Hydrogels with Extremely Enhanced Mechanical Properties

Uniform dispersion of two-dimensional(2 D) graphene materials in polymer matrices remains challenging. In this work, a novel layer-by-layer assembly strategy was developed to prepare a sophisticated nanostructure with highly dispersed 2 D graphene oxide in a three-dimensional matrix consisting of onedimensional bacterial cellulose(BC) nanofibers. This method is a breakthrough, with respect to the conventional static culture method for BC that involves multiple in situ layer-by-layer assembly steps at the interface between previously grown BC and the culture medium. In the as-prepared BC/GO nanocomposites, the GO nanosheets are mechanically bundled and chemically bonded with BC nanofibers via hydrogen bonding,forming an intriguing nanostructure. The sophisticated nanostructure of the BC/GO leads to greatly enhanced mechanical properties compared to those of bare BC. This strategy is versatile, facile, scalable, and can be promising for the development of high-performance BC-based nanocomposite hydrogels.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

In Situ Synthesis of Cuprous Oxide/Cellulose Nanofibers Gel and Antibacterial Properties

Cellulose nanofibers were synthesized by acetobacter xylinum(xylinum 1.1812).The cellulose nanofibers with 30-90 nm width constructed three-dimension network gel,which could be used as a wound dressing since it can provide moist environment to a wound.However,cellulose nanofibers have no antimicrobial activity to prevent wound infection.To achieve antimicrobial activity,the cellulose nanofibers can load cuprous oxide(Cu2O)particles on the surface.The cuprous oxide is a kind of safe antibacterial material.The copper ions can be reduced into cuprous oxides by reducing agents such as glucose,N2H4 and sodium hypophosphite.The cellulose nanofibers network gel was soaked in CuSO4 solution and filled with copper ions.The cuprous oxide nanoparticles were in situ synthesized by glucose and embedded in cellulose nanofibers network.The morphologies and structure of the composite gel were analyzed by FESEM,FTIR,WAXRD and inductively coupled plasma(ICP).The sizes of Cu2O embedded in cellulose nanofibers network are 200-500 nm wide.The peak at 605 cm−1 attributed to Cu(I)-O vibration of Cu2O shits to 611 cm−1 in the Cu2O/cellulose composite.The Cu2O/cellulose nanofibers composite reveals the obvious characteristic XRD pattern of Cu2O and the results of ICP show that the content of Cu2O in the composite is 13.1%.The antibacterial tests prove that the Cu2O/cellulose nanofibers composite has the high antibacterial activities which is higher against S.aureus than against E.coli.

Preparation of Dicarboxyl Cellulose Nanocrystals from Agricultural Wastes by Sequential Periodate-Chlorite Oxidation

Agricultural waste straw is the renewable resource with the highest annual yield in the world.In value-added applications of agricultural waste,dicarboxyl cellulose nanocrystals(DCCs)are prepared from rice,wheat,and corn straw by sequential periodate-chlorite oxidation.In this study,DCCs from rice,wheat,and corn straw were characterized by transmission electron microscopy(TEM),Fourier transform infrared spectrometer,X-ray diffractometer(XRD),and thermal gravimetric analysis(TGA).The carboxyl content of the DCCs was also investigated.XRD results show that the crystallinity index decreased after sequential periodate-chlorite oxidation;however,the cellulose I structure was maintained.TEM results show that rod-shaped DCCs with an average length and width of 287.0 nm and 9.9 nm,respectively,were successfully prepared by sequential periodate-chlorite oxidation.The carboxyl content of the DCCs was around 3.9 mmol/g,and not affected by the type of straw.Experiments to study the removal of copper ions in aqueous medium were performed with the prepared DCCs.The adsorption capacities of copper ions were 131,162,and 144 mg/g for DCCs prepared from rice,wheat,and corn straws,respectively.The results show that DCCs prepared from rice,wheat,and corn straws by sequential periodatechlorite oxidation have potential for the removal of copper ions from aqueous medium.

Preparation of Cellulose Nanofibrils by Multi-Site Regioselective Oxidation

Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are energy intensive because heating and mechanical disintegration are required to produce cellulose fibers below 100 nm in size.In this study,CNFs were prepared through the multi-site regioselective oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)and periodate at room temperature(20–25°C),without any mechanical-disintegration treatment.Transmission electron microscopy(TEM)revealed that the CNFs had the average widths of 14.1,55.4,and 81.9 nm for three different treatments.Fourier-transform infrared spectroscopy revealed that carboxyl groups were created on the surfaces of the microfibrils,while X-ray diffraction studies showed that the cellulose I structure was maintained after oxidation,and that the cellulose nanofibril crystallinity index exceeded 70%.These results demonstrate that CNFs can be prepared by multi-site regioselective oxidation at room temperature in the absence of mechanical disintegration.In addition,a model was developed to calculate the total content of carboxylate and aldehyde groups of CNFs prepared by the TEMPO mediate oxidation,the periodate oxidation,and the multi-site regioselective oxidation methods based on the particle width determined by TEM.The calculated values of the model were in good agreement with the total content(experimental value)of carboxylate and aldehyde groups of CNFs prepared by the TEMPO-mediated oxidation and the multi-site regioselective oxidation methods.However,the model was not valid for CNFs prepared by the periodate oxidation method.

Enhanced Removal of Phosphates by the Adsorbent Consisting of Iron Oxide Loaded on Porous Chitosan/Cellulose Acetate Particle

The effective and economical removal of phosphates from aqueous solution, mostly applied in waste water treatment, is one of the significant issues globally. Removal of phosphates ions in aqueous solution was analysed by chitosan blended with cellulose acetate, and iron oxide loaded chitosan-cellulose acetate adsorbents. The adsorbents were made in the form of beads. Batch experiments were performed to investigate the performance of the beads under various conditions on phosphate adsorption. Contact time, effect of initial phosphate concentration, adsorbent dosage, pH and temperature were investigated. Zeta potential measurements were also undertaken. The results showed that the adsorption process was highly pH dependent. The adsorption kinetics data were modelled with the application of adsorption reaction models and adsorption diffusion models. The results revealed that the pseudo 2nd order model was the best fitting in all cases. The experimental data were tested with Langmuir and Freundlich isotherms. The equilibrium data were well fitted to the Langmuir isotherm model with a maximum adsorption capacity of 958 μg/g. The Freundlich isotherm model also had a close fit with a maximum adsorption of 233 μg/g, which was very close to the experimental maximum adsorption. The mechanism of adsorption followed two stages in which the first one was fast followed by a slower gradual stage. SEM images showed that the adsorbent was macroporous. Fourier Transform Infrared Red (FT-IR) Spectroscopy, X-ray Diffraction Spectroscopy (XRD) and X-ray photoelectron Spectroscopy (XPS) showed that the phosphate adsorption on the HFO-CS/CA beads was due to surface complexes, and mainly involved Nitrogen atoms. HFO loading also increased surface area.

Oxidizing Cellulose to 2,3-Dialdehyde Cellulose by Sodium Periodate

Study on oxidizing cellulose to 2,3-dialdehyde cellulose by sodium periodate （NaIO4） was carried out. The effects of reaction conditions such as pH of solution, temperature, oxidant concentration, oxidation time, the particle size of 2,3-dialdehyde cellulose and alkali treatment temperature on the dialdehyde concentration of cellulose were investigated in detail. The results show that the aldehyde group content was created while reaction temperature and alkali treatment temperature increased.The most principal factors affecting the aldehyde group content of 2,3-dialdehyde cellulose were found out and the best oxidation conditions were as follows: the pH was 2, the reaction temperature was 45 ℃, the mass ratio of cellulose to NaIO4 was 1/2, the reaction time was 4 h, the alkali treatment temperature was 70 ℃ and smaller particle size was 0.80 mm.

Preparation of High Quality Indium Tin Oxide Film on a Microbial Cellulose Membrane Using Radio Frequency Magnetron Sputtering

微生物引起的纤维素(MC ) 膜由醋菌属 xylinum NUST4.1 生产了，为透明的铟锡氧化物(ITO ) 的制造被用作灵活底层电极。透明、传导性的 ITO 薄电影在房间温度使用收音机频率(RF ) 磁控管劈啪作响在 MC 膜上被扔。最佳 ITO 免职条件被检验水晶的结构，有 X 光检查衍射(XRD ) 的表面形态学和 optoelectrical 特征，扫描电子显微镜学(SEM ) ，原子力量显微镜学(AFM ) ，和紫外光谱学完成。样品的表抵抗与一根四点的探针被测量，这部电影的抵抗力是计算的。结果表明扔的 ITO 晶体的比较喜欢的取向强烈依赖于与氧内容(O2/Ar，体积比率) 在劈啪作响的房间。并且 ITO 水晶的结构直接决定扔 ITO 的电影的传导性。高传导性[pBAD33 上的 PBAD 的表抵抗 120 ntrol，能生产 CoQ10 直到 3.24 mg？

Porous Spherical Cellulose Composites Coated by Aluminum (Ⅲ) Oxide and Silicone: Preparation, Characterization and Adsorption Behavior

Porous spherical cellulose composite (PSCA) coated by aluminum(Ⅲ) oxide was prepared and modified by organosilicone. SEM images of the surface morphology of the bead cellulose shows that it has spherical shape and abundant porous structure on its surface. The mapping images of aluminum and silicon of the composite (PSCAS) present aluminum(Ⅲ) oxide and silicone are uniformly dispersed on the surface. The adsorption behavior of PSCAS toward metal ions was determined.

The Dissolution of the Cellulose in the N - ethylmorpholine - N - oxide (NMMO) - Water System with Hydrothermolysis

Tbe N - methylmorpholine - N - oxide (NMMO) - water solvent was used to dissolve the cellulose that was achieved by means of hydrothermolysis. Sample B, RS and WS used here were made from beech, rice straw and wheat straw respectively. They could be completely dissolved in the NMMO - water system. A commercial a - cellulose was employed in the comparative experiment. The entire dissolving process was Investigated. At a given temperature, the vacuum condition applied to the mixture of the cellulose and NMMO - water was very important in order to accelerate the dissolution of cellulose and shorten the dissolving period. After dissolution, degree of polymerization (DP) of all samples was measured by viscometry. Longer dissolving time and higher temperature could cause the degradation of the dissolved cellulose. N- propyl gallate could prevent the degradation of cellulose during the process of dissolution.

Synthesis, Characterization of Cellulose Grafted N-Oxide Reagent and Its Application in Oxidation of Alkyl/Aryl Halides

Oxidation of aliphatic and aromatic halides by N-oxide functionalities supported on 4- vinyl pyridine, (4-VP), grafted cellulose is reported in the present manuscript. Synthesis of graft copolymer of cellulose and poly 4-vinyl pyridine, poly(4-VP), has been carried out using ceric ions as redox initiator. Post-grafting treatment of CellO-g-poly (4-VP) with 30% H2O2 in acetic acid gives Cellulose-g-poly (4-VP) N-oxide, the polymeric supported oxidizing reagent. The polymeric support, CellO-g-poly (4-VP) N-oxide, has been used for oxidation reactions of different alkyl / aryl halide such as 1-bromo-3-methyl butane, 2-bromo propane,1-bromo heptane and benzyl chloride. The polymeric reagent was characterized by IR and thermo-gravimetric analysis. The oxidized products were characterized by FTIR and H1NMR spectral methods. The reagent was reused for the oxidation of a fresh alkyl / aryl halides and it was observed that the polymeric reagent oxidizes the compounds successfully but with little lower product yield.

Structural Study of Cellulose-Iron Oxide Composite Materials

There are limited structural studies of iron oxide coated cellulose materials despite their use as adsorbents for the removal of waterborne arsenic species. This study reports on the structural characterization of cellulose-iron oxide composites at variable iron oxide content using spectroscopy methods (Raman, solids 13C NMR, powder X-ray diffraction (pXRD)) and thermal gravi-metric analysis (TGA). Iron oxide was supported onto cellulose (ca. 25 wt.%) without significant loss in the Fe coating efficiency, where the accessibility of the biopolymer -OH groups affect the coating efficiency and yield of the iron oxide-cellulose composite. Isotherm adsorption studies for cellulose, iron oxide species and the cellulose composite materials with roxarsone (3-nitro- 4-hydroxyphenylarsonic acid) were studied to characterize the surface chemical properties of these potential adsorbent materials.

Electro-conductive Nanocrystalline Cellulose Film Filled with TiO_2-ReducedGraphene Oxide Nanocomposite

Imparting electro-conductive properties to nanocellulosebased products may render them suitable for applications in electronics,optoelectronics, and energy storage devices. In the present work, an electroconductive nanocrystalline cellulose(NCC) film filled with TiO2-reducedgraphene oxide(TiO2-RGO) was developed. Initially, graphene oxide(GO) was prepared using the modified Hummers method and thereafter photocatalytically reduced using TiO2 as a catalyst. Subsequently, an electro-conductive NCC film was prepared via vacuum filtration with the as-prepared TiO2-RGO nanocomposite as a functional filler. The TiO2-RGO nanocomposite and the NCC/TiO2-RGO film were systematically characterized. The results showed that the obtained TiO2-RGO nanocomposite exhibited reduced oxygen-containing group content and enhanced electroconductivity as compared with those of GO. Moreover, the NCC film filled with TiO2-RGO nanocomposite displayed an electro-conductivity of up to 9.3 S/m and improved mechanical properties compared with that of the control. This work could provide a route for producing electro-conductive NCC films, which may hold significant potential as transparent flexible substrates for future electronic device applications.

Facile Fabrication of Conductive Paper-based Materials from Tunicate Cellulose Nanocrystals and Polydopamine-decorated Graphene Oxide

Conductive papers made from graphene and its derivatives are important for the development of electronic devices; however, elastomerbased matrices usually make it difficult for the conductive sheets to form continuous conductive networks. In this work, we used tunicate-derived cellulose nanocrystals(TCNC) instead of traditional elastomers as the matrix for polydopamine(PDA)-coated and reduced graphene oxide(GO) to prepare conductive paper, which, at a low concentration, were better for the formation of conductive networks from conductive sheets. It was found that the Young's modulus of the conductive paper produced via this strategy reached as high as 7 GPa. Meanwhile, owing to the partial reduction of GO during the polymerization of dopamine, the conductivity of the conductive paper reached as high as 1.3×10-5 S/cm when the PDA-coated GO content was 1 wt%, which was much higher than the conductivity of pure GO(～4.60×10-8 S/cm). This work provides a new strategy for preparing environmentally friendly conductive papers with good mechanical properties and low conductive filler content, which may be used to produce high-performance, low-cost electronic devices.

Low Temperature Hydrothermal Synthesis of Ultra-light and Superelastic Graphene Oxide/Cellulose Aerogels for Absorption of Organic Liquids

Two-dimensional(2 D) graphene oxide(GO) nanosheets and 1 D2,2,6,6-tetramethylpiperidin-1-oxyl(TEMPO)-oxidized cellulose nanofibers(TOCN) were assembled into GO/TOCN aerogels via a low temperature hydrothermal and freeze-drying process. The as-prepared GO/TOCN aerogels exhibited interconnected 3 D network microstructures, a low density of 6.8 mg/cm^3, a high porosity up to 99.2% and excellent mechanical flexibility.The high porosity in conjunction with their hydrophobicity(contact angle of 121.5°), allowed the aerogels to absorb different organic liquids with absorption capacities up to 240 times of their own weight, depending on the density of the liquids. These results indicated that the aerogels were excellent candidates as sorbent materials for the clean-up of organic liquids. After five absorption-desorption cycles, the absorption capacity of the TOCN carbon aerogels could be regenerated up to 97% of the initial absorption capability,which demonstrated their excellent recyclability.

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose(cellulose I)can not be oxidized by TEMPO-NaOCl-NaBr system,one of TEMPO-mediated selective oxidant systems,but regenerated cellulose(cellulose Ⅱ)can be completely selectively oxidized.In the present work,natural cellulose pulp was treated with NaOH solution,which concentration is lower than 20 wt%.The alkaline celluloses obtained were oxidized by TEMPO-NaOCl-NaBr system and the factors which influence the selective oxidation reaction rate have been investigated.The structure of the oxidized products has been characterized by Fourier transform-infrared(FTIR),nuclear magenatic resonace(NMR)and wide angle X-ray diffraction(WAXD)methods,and their adsorption properties for Cu2+and Cd2+ in aqueous solutions have been preliminarily examined.The results show that after the alkaline treatment,the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8,the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing.The alkaline treatment has a great effect on the crystal structure of natural cellulose,but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation.The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.