ENVIRONMENTAL RESEARCH
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2020
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IF 5.715
Cong Li,Hongyang Ma,Shyam Venkateswaran,Benjamin S. Hsiao
Carboxylated cellulose filters were fabricated by oxidation of a cellulose fibrous mat via TEMPO-mediated oxidation. These carboxylated cellulose filters were employed as sustainable filters for removal and recovery of lanthanum ions (La (III)) with high adsorption capability. The surface chemistry of the carboxylated cellulose fibers before and after adsorption of La (III) was investigated systematically. The distribution of La (III) on carboxylated cellulose fibers were explored by EDX mapping approach, which revealed that the adsorption occurred on both the surface and the internal structure of the cellulose fibers. The kinetics and isotherms of the adsorption were conducted to understand the adsorption mechanism of the carboxylated cellulose filter and to learn the maximum adsorption capacity for La (III) which was as high as 33.7 mg/g. The adsorption selectivity of the carboxylated cellulose filter for La (III) was determined when interfering ions including mono- and di-covalent ions were involved. The carboxylated cellulose filter exhibited high adsorption capability and high permeation flux evidenced by the breakthrough curves of the dynamic adsorption of La (III) under an extremely low pressure of 0.07 kPa. A variety of desorption reagents were selected to recover lanthanum from the carboxylated cellulose filter, where the optimized conditions for recovery were explored. Finally, a spiral wound cartridge of the carboxylated cellulose fibrous mat was fabricated and the removal and the recovery of La (III, 2.5 ppm) from massive lanthanum-containing water were demonstrated. It was very impressive that the high rejection ratio of 94.3% was achieved under the low pressure drop of 3.0 kPa remaining throughout the separation process, and the treated solution volume was high up to 21.4 L, which was about six-times higher than that of commercially available nanofibrous adsorption membranes, indicating that the carboxylated cellulose filter could be used as a highly efficient adsorption medium for industrial recovery of rare earth metals .
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GREEN CHEMISTRY
·
2020
·Vol. 22
·期 10
·3296-3308
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IF 9.48
Xueqi Chen,Zihui Song,Shaopeng Li,Nguyen Tat Thang,Xing Gao,Xinchao Gong,Minghui Guo
The preparation and functionalization of biomass-based hydrogels that can be used in the field of biomedicine have received an increasing amount of attention. Carbon dots are a kind of fluorescent carbon nanomaterial with stable fluorescence emission and low biotoxicity, therefore the introduction of carbon dots into the biomass-based hydrogel can make it have a broader application prospect. In this work, fluorescent nitrogen-doped carbon dots/cellulose nanofibril composite hydrogel (NCDs/CNF-gel) with exceptional mechanical properties was successfully fabricated by a facile one-pot green hydrothermal treatment. The properties of NCDs/CNF-gel prepared at different temperatures and CNF concentrations were investigated by electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, fluorescence spectroscopy, rheology, and mechanical tests. NCDs/CNF-gel with injectable, pressure-resistance and excellent fluorescence properties can be obtained by controlling the hydrothermal treatment temperature. Furthermore, the self-assembly mechanism of NCDs in the hydrogel network and the improvement mechanism of hydrogel compressive strength were explored. The NCDs/CNF-gel exhibited acid-resistant and alkaline sensitive blue-green fluorescent emission. The outstanding biocompatibility, excellent fluorescence and mechanical properties of NCDs/CNF-gels, and their facile fabrication render these so-prepared gels promising candidates for future biomedical applications.
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JOURNAL OF FOOD ENGINEERING
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2020
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IF 4.499
Ying Ji
The combination of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidization and annealing was applied to modify structural properties of corn starch in order to obtain starch polymer microgels. Microgels were characterized by X-ray diffraction, ATR-FTIR and thermogravimetry analysis (TGA). The effects of microgels on the uptake and release of lysozyme were also analyzed. The formation of oxidized microgels through the crosslinking between starch molecules and sodium trimetaphosphate was confirmed by X-ray diffraction. The ATR-FTIR analysis suggested that TEMPO-oxidation results in the formation of carboxyl groups. TGA data indicated that oxidized-annealed microgels had less thermal stability than oxidized microgels. Furthermore, the oxidized-annealed microgels had an improved capacity for uptake and release of lysozyme. At this stage of the exploration, microgels prepared from corn starches by annealing and oxidation is simple and efficient.
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GREEN CHEMISTRY
·
2020
·Vol. 22
·期 10
·3208-3215
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IF 9.48
Hao Ling,Ruwei Chen,Quanbo Huang,Feng Shen,Yuyuan Wang,Xiaohui Wang
Transparent, flexible, and eco-friendly touch sensors are important components for next-generation green electronics such as wearable sensors and e-skins. However, most current touch sensors, which are based on plastics or glass substrates and indium tin oxide or metal microelectrodes, are not environmentally friendly, as well as being difficult to recycle and expensive. Here, we demonstrate that a green, transparent, flexible, and recyclable nanopaper-based touch sensor (NPTS) can be fabricated via inkjet printing a conductive polymer, poly(3,4-ethylene dioxythiophene)-doped polystyrene sulfonate (PEDOT:PSS), on cellulose nanofibril paper. The materials cost of a single-keypad NPTS with a size of 3.5 cm × 2.5 cm × 0.05 mm is only $0.060. Good printability, excellent transparency (80% at 400 nm), and high conductivity (1360 S cm−1) were achieved with the PEDOT:PSS microelectrodes when using a newly developed, eco-friendly water-based ink formulation. It takes only 3–4 weeks for the NPTS to degrade completely in natural soil. A four-keypad NPTS was demonstrated by interfacing with the Arduino UNO development board. Folding, bending, and multiple finger-touch trials caused only slight capacitive changes to the NPTS, with no loss of function. The facile fabrication of the NPTS will be invaluable for many practical applications where eco-friendly, transparent, flexible, durable, recyclable, and economical touch-control is required.
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REACTIVE & FUNCTIONAL POLYMERS
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2020
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IF 3.333
Bin Chu,Chaoxi Wu,Shunqing Tang,Mei Tu
A sprayable wound dressing is convenient, simple and easy to administer by nonmedical personnel in clinical medicine. In this study, agarose was employed for the first time as a spray for wound care. The strong gelling properties and cross-linked network structure of agarose makes it unsuitable for spraying. Furthermore, agarose gel exhibits shrinkage and is resistant to degradation. These features constitute major disadvantages of agarose as a wound dressing. To overcome these problems, we degraded and modified agarose using the 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation method, prepared degraded carboxylated agarose (Ag-CA) to improve the biodegradability , and developed a microgel structure that is easy to spray. In addition, we grafted dopamine onto Ag-CA (to yield Ag-g-DA) and evaluated its adhesion to cells and wounds. The surface topography , cell adhesion, tissue adhesion and protein release capabilities of the materials were evaluated, and a histological analysis was performed at 1, 2, 3, and 4 weeks. The introduction of carboxyl and catechol functional groups enabled agarose to bind to cells and thereby promote cell adhesion and growth. The wound adhesion and repair due to Ag-CA and Ag-g-DA were superior to those of unmodified agarose. Furthermore, the agarose-derived hydrogels promoted the downregulation of proinflammatory cytokines, suggesting a potential direction for research in skin regeneration and repair.
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Environmental Science and Ecotechnology
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2020
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IF 0
Jing Ding,Lingjun Bu,Bingxin Cui,Guanshu Zhao,Qingwei Gao,Liangliang Wei,Qingliang Zhao,Dionysios D. Dionysiou
Bisphenol (BP) analogues in wastewater effluent and groundwater pose a potential threat to human health due to their ability to disrupt steroidogenesis. A new solar-assisted electrochemical process (SECP) was developed and evaluated for the degradation of BP analogues. The effects of quenchers, current density, initial pH, supporting electrolyte, and aqueous matrix on the removal kinetics of bisphenol AF (BPAF) and bisphenol A (BPA) were investigated. The kinetic constants of BPAF, BPA, and bisphenol S (BPS) in the SECP with irradiation intensity of 500 mW cm −2 were 0.017 ± 0.002 min −1 , 0.022 ± 0.002 min −1 , and 0.012 ± 0.001 min −1 , respectively. The changes in the degradation rates of BPAF, BPA, and BPS in the presence of quenchers indicated the relative contribution of hydroxyl radical ( ● OH) oxidation, anodic electrolysis, and singlet ( 1 O 2 ) oxygenation in the degradation of BPs in the SECP. The enhanced rate of generation of ● OH and 1 O 2 was observed in the SECP compared with those in the conventional electrochemical system. The identification of the transformation products (TPs) of BPAF demonstrated that hydroxylation, ring cleavage, β-scission, and defluorination were the major processes during the oxidation in the SECP. The conversion to fluoride ions (76%) and mineralization of total organic carbon (72%) in the SECP indicated further degradation of TPs. The results from this study improved our understanding of the degradation of BP analogues in the electrooxidation irradiated by solar light and help to establish the application potential of the SECP for the effective degradation of emerging contaminants in wastewater.
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COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2020
·
IF 6.444
Yiming Chen,Liang Pang,Yang Li,Heng Luo,Gaigai Duan,Changtong Mei,Wenhui Xu,Wei Zhou,Kunming Liu,Shaohua Jiang
Exploring an electromagnetic interference (EMI) shielding material with lightweight, flexible and easy fabricating process to deal with the increasingly serious electromagnetic environment pollution has become a current developing trend. Here, we reported a novel cellulose nanofiber (CNF)/silver nanowire (AgNW) conductive paper with a distinctive hierarchical structure by a facile “blending-filtration-peeling” process. Results showed that the obtained paper with a thickness of ~40 μm exhibited excellent tensile strength of ~49.1 MPa, a low percolation threshold of 1.4 vol% AgNWs, no significant changes in electrical conductivity after 2000 bending. The outstanding synergy between green CNFs and AgNWs endowed the paper with high EMI shielding effectiveness of up to 39.3 dB in X band and effective shielding effects on electromagnetic signals for realistic mobile phone communication. The special CNF/AgNW papers are expected to broaden new application fields as electronic devices e.g. flexible electronic components or effective ultra-thin EMI shielding materials for daily demands.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
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IF 5.162
Qifeng Chen,Jieyi Xiong,Guangxue Chen,Taiyan Tan
In this paper, nanocellulose was extracted from agricultural waste corn husks. Transparent hydrophobic membranes containing silica were fabricated through two facile methods including surface coating and internal grafting. The results showed that: the nanocellulose prepared by TEMPO-mediated oxidation and high pressure homogenization not only retained the type and crystal structure of the original cellulose , but also increased the crystallinity to 64.5% and improved the thermal stability . Both surface coating and internal grafting methods had successfully loaded silica onto films. The internal grafting film had a silica content of 10.5%, which was mainly present inside the film. The light transmittance of this film was 84.4% and the surface contact angle to water was 152.6°. The content of silica on the surface coating film was 5.7%, and they were mainly distributed on the surface of the film to form a nano-scale rough surface. The light transmittance of the surface coating film was 87.8% and the surface contact angle to water was 165.7°. Compared to the film prepared by internal grafting method, the nanocellulose film prepared by surface coating method contained less nano silica and had better properties including higher transparency, higher surface roughness and excellent hydrophobic anti-fouling properties.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
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IF 5.162
Kaiwei Zhang,Songming Zheng,Yuqing Liu,Jinyou Lin
Cellulose nanofibrils (CNF) is a natural nanomaterial composed of biomacromolecules that can be extracted from plants and has great potential applications in many fields due to its excellent regenerative, sustainable, and biodegradable properties. In this work, the flax CNF with hierarchical scales was obtained by using the flax fibers (FF) treated with different concentrations of alkaline solution, followed by the TEMPO-mediated ternary oxidation and mechanical treatment. Subsequently, the resultant CNF was implanted on the commercial filter paper as a surface barrier for oil/water preparation. The changes of cellulose crystal form and crystallinity caused by alkali treatment on FF were studied by Fourier transform infrared spectroscopy and X-ray diffraction. Morphological changes of FF before and after alkali treatment were observed. The morphology of obtained CNF was examined. Moreover, the transmittance of the prepared CNF suspension and films was also investigated by a UV spectroscopy . The prepared modified filter paper can effectively separate the oil/water mixture, which gives themselves promise as candidates in practical applications of oil/water separation.
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BIOMACROMOLECULES
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2020
·
IF 6.092
Yanlei Hu,Liang Liu,Juan Yu,Zhiguo Wang,Yimin Fan
Native biopolymer nanofibers (cellulose, chitin, and silk nanofiber) are one of the most important contributors to the outstanding functions and mechanical properties of natural materials. To enhance the mechanical performance, A great deal of top-down routes have been reported to prepare biopolymers nanofibers/nanowhiskers that retaining their nanostructures. Compared with advances in cellulose and chitin nanofibers/nanowhiskers, it remains difficult for direct downsizing the natural silk fibers into silk nanofibers/nanowhiskers (SNFs/SNWs) because of their high crystallinity and sophisticated structures. In this work, environmentally friendly and recyclable deep eutectic solvents (DESs) were used to direct pretreat and downsize natural silks into silk nanowhiskers with high yield. SNWs with similar diameter (3.1–22 nm for OA/ChCl DES treated SNWs, 2.7–20 nm for CA/ChCl DES treated SNWs) and contour length (329 ± 140 nm for OA/ChCl DES treated SNWs, 365 ± 200 nm for CA/ChCl DES treated SNWs) to individual nanofibers in natural silk fibers were obtained. In addition, the separated DES with a recovery yield of at least 92% could be reused four times to produce SNWs, indicating the possibility of DESs as green solvents for sustainable biopolymer nanomaterial extraction. Based on the inherent amphoteric properties of SNWs, multicompatibility was explored to facilely composite SNWs with various polymers for preparation of coextruded membranes with enhanced performance and endowed the composites with protein-endowed double adsorption properties. Overall, this work demonstrated that the DES pretreatment process is promising for green and low-cost biopolymer nanomaterial extraction and that the SNWs prepared via DES have good prospects as nanoscale materials in the environmental field and in development of smart biomaterials and drug delivery in biomedicine.
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ACS Omega
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2020
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IF 2.87
Jun Zhang,Meng Wang,Wenli Peng,Zhengcan Chen,Zhenbin Chen
A novel glutathione (GSH) surface molecularly imprinted polymer (SMIP) was prepared using modified macroporous adsorption resin (MAR) CLX1180 as a solid substrate, glutathione as a template, acrylamide (AM) and N-vinyl pyrrolidone (NVP) as functional monomers, and N,N′-methylenebisacrylamide (NMBA) as a cross-linker. The reaction could be initiated by three different ways, using CLX1180, GSH, and both, which was proved by the experimentation. The morphology and structure of this polymer were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and time-of-flight mass spectrometry (TOF-MS). The maximum adsorption capacity of GSH approached 39.03 mg·g–1, and the separation degree related to l-cysteine was as high as 4.18. Pseudo-first-order and Langmuir models were well fitting the adsorption properties. GSH-SMIP could be used for three adsorption/desorption cycles with only a slight decrease of adsorption capacity.
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CARBOHYDRATE POLYMERS
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2020
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IF 7.182
Ya Liu,Yipeng Zhang,Tougen Liao,Li Gao,Meng Wang,Xu Xu,Xinxin Yang,He Liu
Boron nitride nanosheets (BNNSs) are desirable materials for thermal management applications owing to their excellent thermal conductivity. Such property also related to the increased thermal transfer efficiency per unit mass, which can be improved by constructing three-dimensional (3D) structures. Cellulose nanofibers (CNFs) are often used to prepare 3D skeletons and stabilize the dispersion of inorganic fillers. Therefore, CNF/BNNS aerogels were prepared to disperse BNNS in a 3D network. CNF/BNNS aerogel exhibited a thermal conductivity of 0.57 W m −1 K −1 , which is an enhancement of 443 % compared to 0.105 W m −1 K −1 of CNF aerogel. The surface temperature changes of the aerogels were confirmed a strong thermal management capacity. The BNNSs also resulted in the compressive strength increased from 0.25 MPa (CNF aerogel) to 0.37 MPa (CNF/BNNS aerogel). This study provides an effective strategy for the preparation of cellulose-based nanocomposite aerogels with excellent thermal management properties and mechanical properties.
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