CELLULOSE
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2019
·Vol. 26
·期 11
·6653-6667
·
IF 3.917
Chen Yiming,Zhou Lijie,Chen Lian,Duan Gaigai,Mei Changtong,Huang Chaobo,Han Jingquan,Jiang Shaohua
Abstract Directional freeze-drying is considered to regulate the structure of nanocellulose aerogels with special performances. In this work, TEMPO-oxidized cellulose nanofiber aerogels with high porosity (> 99.5%) and low density (~ 7 mg/cm 3 ) were produced by different freeze-drying methods. The effects of temperature, freezing reagents and freezing methods on the structure and properties of aerogels were investigated. Among them, an anisotropic cellulose aerogel was obtained using a simple and flexible directional freezing in ethanol of − 30 °C by a self-made directional freezer. Our results demonstrated that it could present honeycomb-like pores in the transverse direction and regular directional tunnels in the longitudinal direction, and some attractive features, such as high water adsorption (120 g/g) and stability in water. Compared with other aerogels, this anisotropic structure also provided the aerogel with excellent compressive property (15.2 kPa) and faster liquid transport (4.95 mm/s) in the longitudinal direction than in other directions. The distinctive aerogels based on nanocellulose by directional freeze-drying are also expected to be combined with multifunctional materials to achieve directional applications to meet the requirements of different fields. Graphic abstract
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JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
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2019
·
IF 3.261
Zhuang Wang,Xiaofeng Xie,Xiao Wang,Asad Mahmood,Hanxun Qiu,Jing Sun
In realistic Volatile organic compounds (VOC)-containing polluted air, VOCs often do not exist alone, but different VOCs coexist. The interaction between different VOCs affects their photodegradation. However, few studies have focused on the photodegradation of mixed VOCs. Herein, rGO-TiO 2 photocatalysts were synthesized by a modified refluxing-solvothermal method, and applied to photocatalytic degradation of single VOC (p-xylene and ethylene) and VOC mixture (containing benzene, toluene, p-xylene). It was found that rGO-TiO 2 possessed higher photocatalytic degradation activity for single VOC and VOC mixture than pure TiO 2 . The increased single VOC adsorption capacity, more efficient light harvesting ability, and enhanced separation efficiency of electron-hole were responsible for improved degradation performance of rGO-TiO 2 . In addition, superoxide radicals played a more important role than hydroxyl radicals for removing both p-xylene and ethylene. Interestingly, commercial TiO 2 (P25) underwent decreased efficiency (80.0% to 63.8%) in photodegrading from single p-xylene to p-xylene in VOC mixture, while it was remained unchanged (93.5%–93.0%) for T0.2G (0.2% mass ratio of reduced graphene oxide to TiO 2 ). This could be mainly attributed to sufficient adsorption sites provided by rGO sheets to mitigate competitive adsorption. Simultaneously, its photocatalytic activity showed no obvious decrease after five photodegradation cycles of mixed VOCs. These results suggested great potential of efficient photodegradation of VOC mixture by rGO-TiO 2 .
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2019
·
IF 2.931
Guorong Li,Qingqin Wang,Yarong Wu,Yi Li,Liangqia Guo
In this work, photoactivated oxidase mimetics was prepared by copolymerizing dicyandiamide with barbituric acid (BA) and characterized by X-ray diffraction pattern, Fourier transformed infrared spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy , photoluminescence spectrum , diffuse reflectance spectrum. Experimental results and density functional theory calculation indicated that the substitution of nitrogen atoms by carbon atoms in tri- s -triazine structure due to the copolymerization of BA enhanced visible light absorption and weakened the barrier of photocarrier transfer. In the presence of visible light and oxygen, 3, 3′, 5, 5′-tetramethylbenzidine was oxidized under the catalysis of photoactivated oxidase mimetics to produce a green colored product, which could be reduced by glutathione (GSH). Therefore, a facile method based on the photoactivated oxidase mimetic has been developed for colorimetric detection of GSH. The linear range for GSH was ranged from 2.0 to 50.0 μmol L −1 (R 2 = 0.998) with the detection limit of 1.4 μmol L −1 . The proposed method was applied to detect the cellular GSH with satisfactory results.
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Journal of Physical Chemistry C
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2019
·
IF 4.309
Zepeng Rao,Xiaofeng Xie,Xiao Wang,Asad Mahmood,Shengrui Tong,Maofa Ge,Jing Sun
A series of Er-doped TiO2 photocatalysts, using Er(NO3)3·6H2O precursor ranging from 0.5 to 2 mol %, were synthesized via sol–gel method with titanium(IV) isopropoxide solution as reactant. The structure and properties of as-prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, thermogravimetric analysis, photoluminescence, electrochemical impedance spectroscopy, and photocurrent. The as-synthesized Er-doped TiO2 nanoparticles demonstrated improved photocatalytic activities for the photodegradation of selected volatile organic compounds, including acetaldehyde, o-xylene, and ethylene. Additionally, high photodegradation of acetaldehyde was recorded in the visible region (λ > 420 nm). XPS analysis revealed that a handful of Er in anatase TiO2 was presented in the form of Er2O3, which benefited by increasing the specific surface area ranging from 59.28 to 110.34 m2/g and consequently enhanced the adsorption capacity for acetaldehyde, o-xylene, and ethylene 3.3, 3.7, and 3.8 times, respectively, in contrast to the undoped TiO2. Electron spin resonance results showed that Er doping caused production of oxygen vacancies (VO) and Ti3+, which promoted the photocatalytic activity of the catalyst. The TiO2 samples containing 0.5–1.5% Er content exhibited higher photoactivity in comparison with other samples. The highest removal efficiency of acetaldehyde and o-xylene within 100 min was 99.2 and 84.6%, respectively, and ethylene degradation efficiency reached 22.4% within 180 min. Furthermore, the visible light elimination efficiency of acetaldehyde was 25.5%. Finally, the results suggested that Er doping predominantly inhibited the catalyst poisoning in the degradation of o-xylene.
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POLYMER
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2019
·
IF 3.771
Jie Chen,Fushan Chen,Yahui Meng,Shuangfei Wang,Zhu Long
The pursuit of sustainable plastic packaging materials stimulates the development of new materials based on renewable resources and efficient fabrication methods. In this study, thermoplastic hydroxypropyl starch (TPS) as a matrix and oxidized microcrystalline cellulose (MCC) as a reinforcing agent were used to prepare water-soluble composite films via a hot-compression molding technique. As-prepared composite films were disintegrated in water in approximately 60 s, which could potentially reduce plastic pollution in the environment. In addition, MCC was treated to enhance the tensile strength of composite films, with a remarkable increase of ∼249.42%. The composite films are composed of renewable, biodegradable, and environment-friendly materials, and the fabrication process is environmentally benign, highly efficient, cost-effective, and easy for scaling up. The new composite films can be used as a renewable water-soluble material for industrial applications.
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FOOD HYDROCOLLOIDS
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2019
·
IF 5.839
Xingzhong Zhang,Yingli Liu,Yixiang Wang,Xiaogang Luo,Yan Li,Bin Li,Jing Wang,Shilin Liu
In order to enhance the surface hydrophobicity and emulsifying capacity of cellulose nanofibrils, a ‘green’ surface-modification with protein nanoparticles was conducted. The adsorption of soy protein isolate (SPI) nanoparticles on the bacterial cellulose oxidized by 2,2,6,6-tetramethylpiperidine-nitrogen-oxide (TEMPO) through electrostatic attraction at pH 3 was investigated. The experimental results demonstrated that the modification increased the surface hydrophobicity of TEMPO-oxidized bacterial cellulose (TOBC), and the complexes expressed the improved interfacial rheological properties. Accordingly, with the increasing contents of complexes, the Pickering emulsions exhibited the smaller droplets size, higher viscosity, and better physical stability. Moreover, the emulsions showed good anti-oxidative stability, where both primary (POVs) and secondary (TBARS) products of lipid oxidation were significantly lower than those of oil without coverage. The results of in vitro digestion indicated the improved anti-lipid hydrolysis performance of emulsions with tunable interfacial structure formed by complexes.
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CHEMICAL ENGINEERING JOURNAL
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2019
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IF 8.355
Yizhen Zhang,Lifen Liu,Qiyuan Chen,Yun He,Michael K.H. Leung
A novel system including peroxymonosulfate (PMS) activation process in a photocatalytic fuel cell (PFC) was established, promoting the degradation efficiency of berberine and enhancing the simultaneous electricity generation. The cathode is based on carbon-fiber cloth (CC) and loaded CoFe 2 O 4 with carbon nano-fibers (CNFs), matching well with Ag NPs/ZnO NRs/NiF photo-anode to drive PFC work. The CNFs/CoFe 2 O 4 /CC cathode is multifunctional, it can activate PMS for sulfate radical ( SO 4 - · ) generation, and can simultaneously accept electrons from photo-anode for transform between Co 3+ and Co 2+ . The adding of PMS in PFC system boosts radical formation and cyclic reactions between related species. This PFC-PMS system showed a high antibiotic degradation efficiency and stable electricity generation (93.5% for berberine degradation, 9.18 h −1 for kinetic rate constant, ~0.50 V for cell-voltage at 2000 Ω). In addition, the pollutant removal capacity, influencing factors and the pollutant degradation mechanism in PFC-PMS system were illustrated. The feasible mechanism of berberine degradation was elucidated by the radical trapping and EPR test and these results confirmed that the formation of reactive species, including SO 4 - · , OH, O 2 - · , 1 O 2 radicals and holes. This study suggests that the established PFC-PMS system is more efficient in wastewater treatment and simultaneous energy recovery.
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CELLULOSE
·
2019
·Vol. 27
·期 3
·1385-1391
·
IF 3.917
Cao Xinwang,Zhu Mengting,Fan Fangwei,Yang Yinzhi,Zhang Qiang,Chen Yiren,Wang Xin,Deng Zhongmin
In this study, all-cellulose nanocomposites were developed by depositing one-dimensional jute cellulose nanowhiskers on a hydrolyzed two dimensional electrospun nanofibrous membrane via an immersion-drying process. The prepared nanocomposites were characterized by Fourier Transform Infrared, field emission scanning electron microscope, thermal gravimetric analysis, Brunauer, Emmett and Teller specific surface area, and mechanical properties. The versatile all-cellulose nanocomposites have the potential to be used in ultrafiltration, medical application, catalyst supports, etc.
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Nanomaterials
·
2020
·Vol. 10
·期 1
·112
·
IF 4.324
Huixiang Wang,Subir Kumar Biswas,Sailing Zhu,Ya Lu,Yiying Yue,Jingquan Han,Xinwu Xu,Qinglin Wu,Huining Xiao
Recently, with the development of personal wearable electronic devices, the demand for portable power is miniaturization and flexibility. Electro-conductive hydrogels (ECHs) are considered to have great application prospects in portable energy-storage devices. However, the synergistic properties of self-healability, viscoelasticity, and ideal electrochemistry are key problems. Herein, a novel ECH was synthesized by combining polyvinyl alcohol-borax (PVA) hydrogel matrix and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-cellulose nanofibers (TOCNFs), carbon nanotubes (CNTs), and polyaniline (PANI). Among them, CNTs provided excellent electrical conductivity; TOCNFs acted as a dispersant to help CNTs form a stable suspension; PANI enhanced electrochemical performance by forming a “core-shell” structural composite. The freeze-standing composite hydrogel with a hierarchical 3D-network structure possessed the compression stress (~152 kPa) and storage modulus (~18.2 kPa). The composite hydrogel also possessed low density (~1.2 g cm−3), high water-content (~95%), excellent flexibility, self-healing capability, electrical conductivity (15.3 S m−1), and specific capacitance of 226.8 F g−1at 0.4 A g−1. The fabricated solid-state all-in-one supercapacitor device remained capacitance retention (~90%) after 10 cutting/healing cycles and capacitance retention (~85%) after 1000 bending cycles. The novel ECH had potential applications in advanced personalized wearable electronic devices.Keywords:cellulose nanofibers;carbon nanotube;polyaniline;hydrogels;supercapacitor
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CHEMICAL ENGINEERING JOURNAL
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2019
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IF 8.355
Qinglong Zeng,Xiao Wang,Xiaofeng Xie,Guanhong Lu,Yan Wang,Shun Cheng Lee,Jing Sun
Differing from the photocatalysis of liquid contaminant, the capture of gaseous molecule is an essential factor on the photocatalytic activity because of the fast and random motion of gaseous molecule. TaS 2 is a two-dimensional material with good conductivity and large specific area, which are beneficial to the adsorption of gaseous pollutant and the separation of photo-induced e − -h + pairs. Here, P25/TaS 2 (P25: commercial TiO 2 ) was synthesized for the first time to explore the effect of the addition of TaS 2 on the photocatalytic degradation of gaseous acetaldehyde. It turned out that the existence of TaS 2 provided two merits: on the one side, the adsorptive capacity of P25/TaS 2 for gaseous acetaldehyde boosted greatly with the highest adsorptive amount of 234.4 mL, which was three times of that of P25 (76.4 mL); on the other side, the separation efficiency of e − -h + pairs of P25/TaS 2 also increased extremely with the highest photo-current response of 15.5 μA/cm 2 , which was almost four times of that of P25 (4.2 μA/cm 2 ). These two merits made P25/TaS 2 have superior photocatalytic activity for the degradation of gaseous acetaldehyde with the highest removal ratio of 98%, which was twice of that of P25 (48%). The cyclic experiments verified that P25/TaS 2 could keep excellent cycling stability after 6 cycles usage. In addition, proved by electron spin resonance (ESR) analyses and radicals quenching tests, superoxide radical was the decisive active species for the degradation of gaseous acetaldehyde compared with hydroxyl radical. Briefly, this work not only created the pioneer of the application of TaS 2 in the photocatalytic field but also verified TaS 2 an efficient co-catalyst in gaseous photocatalysis.
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JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Qinglong Zeng,Xiaofeng Xie,Xiao Wang,Guanhong Lu,Haiwei Li,Shun Cheng Lee,Jing Sun
Although coupling reduced graphene oxide (RGO) with TiO 2 is believed to enhance the photocatalysis through the light utilization, studies on its photothermal conversion effect are rarely reported. Herein, RGOP (reduced graphene oxide/P25) was synthesized to explore roles of the enhanced light adsorption and photothermal conversion in the photocatalytic process. It was found that although RGOP had increased absorbance, it actually possessed lower available light utilization compared with P25. In the synergistic effect of available light utilization, transfer resistance and hydrophilicity, RGOP exhibited less superoxide radicals but more hydroxyl radicals. In the presence of scavenger experiments, O 2 − was proved to play the predominant role in the photocatalytic process, while OH was the secondary one. In comparison to P25, the change of active radicals of RGOP was adverse to its photocatalysis. However, due to the superior adsorptive property of RGOP, it exhibited higher photocatalytic activity than P25. The improved photocatalytic activity of RGOP was ascribed to its superior adsorptive ability aside from active radicals ( O 2 -, OH).
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Nuclear Science and Techniques
·
2018
·Vol. 29
·期 7
·1-8
·
IF 1.085
Bian Zhong-Xuan,Miao Xia-Ran,Lin Jin-You,Tian Feng,Bian Feng-Gang,Li Hui
Cellulose nanofibrils (CNFs) are a type of natural nanomaterials extracted from plants and animals that have expanding applications in numerous areas benefiting from their inherent properties of renewability, biodegradability, and sustainability. For energy consumption reduction, CNFs were extracted from raw jute fibers, which were not pretreated in a hot alkali or acid solution, by TEMPO-mediated oxidation. Synchrotron radiation wide-angle scattering was performed to realize the crystallization of the CNF crystallites; Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy were used to characterize the changes in chemical groups and visualized morphology of CNFs. The simplified preparation and shortened cycle should further help the study of the structure–function relationship of jute CNFs subjected to chemical modification.
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