Nanoscale
·
2017
·Vol. 9
·期 44
·17593-17600
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IF 7.367
Min Wang,Xiangqian Fan,Lingxia Zhang,Jianjun Liu,Beizhou Wang,Ruolin Cheng,Mengli Li,Jianjian Tian,Jianlin Shi
Porous activated carbons (PACs) are promising candidates to capture CO2 through physical adsorption because of their chemical stability, easy-synthesis, cost-effectiveness and good recyclability. However, their low CO2 adsorption capacity, especially low CO2/N2 selectivity, has limited their practical applications. In this work, an optimized PAC with a large specific surface area, a small micropore size, and a large micropore volume has been synthesized by one-step carbonization/activation of casein using K2CO3 as a mild activation agent. It showed a remarkably enhanced CO2 adsorption capacity as high as 5.78 mmol g−1 and an excellent CO2/N2 selectivity of 144 (25 °C, 1 bar). Based on DFT calculations and experimental results, the coexistence of adjacent pyridinic N and –OH/–NH2 species was proposed for the first time to make an important contribution to the ultra-high CO2 adsorption performance, especially CO2/N2 selectivity. This work provides effective guidance to design PAC adsorbents with high CO2 adsorption performance. The content of pyridine N combined with –OH/–NH2 was further elevated by additional nitrogen introduction, resulting in a further enhanced CO2 adsorption capacity up to 5.96 mmol g−1 (25 °C, 1 bar). All these results suggest that, in addition to the well-defined pore structure, pyridinic N with neighboring OH or NH2 species played an important role in enhancing the CO2 adsorption performance of PACs, thus providing effective guidance for the rational design of CO2 adsorbents.
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CHEMOSPHERE
·
2017
·
IF 4.208
Xiaohua Ren,Huanhuan Guo,Jinkui Feng,Pengchao Si,Lin Zhang,Lijie Ci
3D porous N-doped reduced graphene oxide (N-rGO) aerogels were synthesized by a hydrothermal reduction of graphene oxide (GO) with urea and following freeze-drying process. N-rGO aerogels have a high BET surface of 499.70 m 2 /g and a high N doping content (5.93–7.46 at%) including three kinds of N (graphitic, pyridinic and pyrrolic). Their high catalytic performance for phenol oxidation in aqueous solution was investigated by catalytic activation of persulfate (PS). We have demonstrated that N-rGO aerogels are promising metal-free catalysts for phenol removal. Kinetics studies indicate that phenol degradation follows first-order reaction kinetics with the reaction rate constant of 0.16799 min −1 for N-rGO-A(1:30). Interestingly, the comparison of direct catalytic oxidation with adsorption-catalytic oxidation experiments indicates that adsorption plays an important role in the catalytic oxidation of phenol by decreasing the phenol degradation time. Spin density and adsorption modeling demonstrates that graphitic N in N-rGO plays the most important role for the catalytic performance by inducing high positive charge densities to adjacent carbon atoms and facilitating phenol adsorption on these carbon sites. Furthermore, the activation mechanism of persulfate (PS) on N-rGO was first investigated by DFT method and PS can be activated to generate strongly oxidative radical (SO 4 · - ) by transferring electrons to N-rGO.
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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
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2014
·Vol. 118
·期 3
·1441-1449
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IF 2.206
Qiu Xiaolin,Lu Lixin,Zhang Zhixiong,Tang Guoyi,Song Guolin
This study focused on preparation and thermal properties of poly(stearyl methacrylate) shell (PSMA) microcapsules containing n -octadecane as a phase change material (PCM). Pentaerythritol triacrylate (PETA) and divinylbenzene (DVB) were employed as crosslinking agents. The surface morphologies, particle sizes, and distributions of the microencapsulated phase change material (microPCM) were studied by scanning electron microscopy. The thermal properties, thermal reliabilities, and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry and thermal gravimetric analysis. The microPCM with DVB exhibits higher phase change enthalpies of melting (87.9 J g −1 ) and crystallization (94.8 J g −1 ) and a greater thermal stability in comparison with the microPCM with PETA. The phase change temperatures and enthalpies of the microPCMs varied little after thermal cycles. Thermal images showed that the gypsum board with PSMA/ n -octadecane microPCM possessed temperature-regulated property. Therefore, microencapsulated n -octadecane with PSMA as shell has good thermal energy storage and thermal regulation potential.
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POLYMER
·
2013
·
IF 3.379
Houluo Cong,Lei Li,Sixun Zheng
In this work, we reported the synthesis of poly(N-isopropyl acrylamide)- block - poly(N-vinylpyrrolidone)- block -poly(N-isopropylacrylamide) triblock copolymer (PNIPAAm- b -PVPy- b -PNIPAAm) via reversible addition-fragmentation chain transfer polymerization/macromolecular design via the interchange of xanthate (RAFT/MADIX) process. This approach was further employed to prepare the PNIPAAm- b -PVPy block copolymer networks with N,N′-methylenebisacrylamide as the crosslinker. The results of small angle X-ray scattering (SAXS) indicate that the PNIPAAm- b -PVPy block copolymer networks were microphase-separated, in which PVPy was dispersed into PNIPAAm matrix as the microdomains. The architecture of block copolymer networks allows investigating the effect of the blocked permanently hydrophobic chains ( viz. PVPy) on the deswelling and reswelling behavior of the PNIPAAm hydrogels. It was found that the diffusion of water molecules in PNIPAAm- b -PVPy block copolymer networks was in a non-Fickian and accelerating manner. The swelling ratios of the PNIPAAm- b -PVPy hydrogels were significantly higher than that of control PNIPAAm hydrogel. Compared to control PNIPAAm hydrogel, the PNIPAAm- b -PVPy hydrogels displayed an accelerated response to the external temperature changes in terms of deswelling and reswelling tests. The accelerated thermoresponsive properties is ascribed to the presence of the PVPy blocks in the PNIPAAm- b -PVPy block copolymer networks, which could act as the hydrophilic tunnels to facilitate the diffusion of water molecules in the PNIPAAm networks.
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JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY
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2013
·
IF 0.9
Yihang Lv,Hui Ma,Dongdong Gao,Yi Zhong,Hong Xu,Zhiping Mao
Adhesive polymers, which contain an unusual amino acid, 3,4-dihydroxyphenylalanine (DOPA), can bind strongly to all organic or inorganic surfaces. However, due to DOPA’s poor solubility in organic solvents, it is difficult for us to get desired adhesive polymers. In this paper, poly(N-benzyloxycarbonyl-3,4-dihydroxyphenylalanine) (PNBD) was synthesized based on the modified L-DOPA. Gel Permeation Chromatography was used to analyze the molecular weight of PNBD. The structure of PNBD was characterized by Fourier Transform Infrared Spectroscopy and Hydrogen-1 Nuclear Magnetic Resonance. The adhesive properties of PNBD were determined by lap shear tensile strength tests. The results indicated that PNBD was prepared successfully and had formidable adhesive performance on the various substrates.
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RSC Advances
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2015
·Vol. 5
·期 120
·99418-99424
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IF 3.84
Jinda Fang,Ke Zhang,Jingwei Jia,Zhengke Wang,Qiaoling Hu
To improve the drug-loading capacity and control the initial release of amphiphilic drug carriers, a series of N-phthaloyl-chitosan-g-(PEO–PLA–PEO) compounds were synthesized with well-defined structures. The self-assembly behavior of copolymers in aqueous solutions was confirmed by various techniques such as fluorescence spectrometry, dynamic light scattering, and transmission electron microscopy. The results demonstrated that the micellization behavior of graft copolymers was different from that of their linear counterparts. The micelle sizes of the graft copolymers could be tuned with chemical composition as well as temperature. Furthermore, when hydrophobic indomethacin was loaded into the micelles, the graft copolymer micelles trapped more indomethacin than PEO–PLA–PEO micelles, facilitating the in vitro control of the initial burst release of the drug. Drug release could be controlled in vitro by simply altering the EO/LA ratio of the grafting chains. The graft copolymer showed low cytotoxicity to 293T cells, indicating its great potential application for drug delivery.
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ACS Applied Materials & Interfaces
·
2015
·
IF 6.723
Dongdong Xu,Huanan Yu,Qun Xu,Guiheng Xu,Kaixi Wang
In this work, we report a simple method to fabricate smart polymers engineered with hierarchical photonic structures of Morpho butterfly wing to present high performance that are capable of color tunability over temperature. The materials were assembled by combining functional temperature responsivity of poly(N-isopropylacrylamide)-co-acrylic acid (PNIPAm-co-AAc) with the biological photonic crystal (PC) structure of Morpho butterfly wing, and then the synergistic effect between the functional polymer and the natural PC structure was created. Their cooperativity is instantiated in the phase transition of PNIPAm-co-AAc (varying with the change of temperature) that can alter the nanostructure of PCs, which further leads to the reversible spectrum response property of the modified hierarchical photonic structures. The cost-effective biomimetic technique presented here highlights the bright prospect of fabrication of more stimuli-responsive functional materials via coassembling smart polymers and biohierarchical structures, and it will be an important platform for the development of nanosmart biomaterials.
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Journal of Energy Chemistry
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2015
·
IF 2.352
Feifei Sun,Yue An,Lecheng Lei,Fuying Wu,Jingke Zhu,Xingwang Zhang
Hydrogenation of carbazole and N-ethylcarbazole over Raney-Ni catalyst were realized in the temperature range of 393–503 K. 4[H] adduct dominated the hydrogenation products and the formation of 2[H] adduct was the rate-limiting step during the period, in which the conversion of carbazole was less than 40%. The hydrogenation process followed pseudo-first-order kinetics and the hydrogenation activation energies of carbazole and N-ethylcarbazole were 90 kJ/mol and 115 kJ/mol, respectively. The reaction starting position as well as the pathway of the hydrogenation of (N-ethyl)carbazole were investigated by comparing the kinetic characteristics of hydrogen uptake of carbazole and N-ethylcarbazole. The results showed that the reaction was a stepwise hydrogenation process and the first H 2 was added to the C1 = C10 double bond in the hydrogenation.
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CHEMICAL ENGINEERING SCIENCE
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2014
·
IF 2.613
Huidong Zheng,Weifeng Ren,Kunxiong Chen,Yao Gu,Zhengshuai Bai,Suying Zhao
An experimental study of the mass transfer rates in single drops with simultaneous Marangoni convection was carried out, using a system in which acetic acid was transferred from water to n -propyl acetate. In all experimental trials, high purity deionized water was employed as the continuous phase while n -propyl acetate served as the dispersed phase. The effects of both the drop diameter and the initial solute concentration in the continuous phase on the mass transfer were examined. The results demonstrated that mass transfer is increased as the drop size decreases and exhibits a maximum at an acetic acid concentration in the aqueous solution of 0.15 g/ml which reveals the competing mechanisms between reduction of velocity and mass transfer enhancement due to Marangoni effects. All current models, including the Newman (1931) model, do not account for the influence of the initial solute concentration, and thus a correction factor, α , was introduced to obtain the factor, R ׳ , by which the effective diffusivity is enhanced, based on Steiner׳s (1986) modified Newman model. This α factor is a function of the initial difference in solute concentration. The mass transfer rates predicted by our modified Newman model were in good agreement with the experimental data obtained in the present study.
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ELECTROCHIMICA ACTA
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2013
·
IF 3.777
Jiu-Ju Feng,Zhang-Ying Lv,Su-Fang Qin,Ao-Qi Li,Yao Fei,Ai-Jun Wang
Au porous textile-like sheet arrays (AuPTSAs) have been facilely prepared on a glassy carbon electrode (GCE) by one-step electrodeposition, which are performed at -0.4 V for 600 s in the electrolysis solution containing 10 mM HAuCl 4 , 1.25 M N -methylimdazole and 0.5 M H 2 SO 4 . N -methylimdazole plays an important role in the formation of the gold nanostructures. This approach is simple and facile, whereas no additional issues such as seeds, templates, and surfactants are required. Thus prepared AuPTSAs are perpendicular to the electrode surface and growing in the (1 1 1) directions and their growth mechanism is discussed in some detail. The AuPTSAs show enhanced electrocatalytic activity with better stability toward methanol oxidation in alkaline media, compared with those of polycrystalline Au nanoparticles.
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CLINICAL NUTRITION
·
2014
·
IF 3.94
Lulu Xia,Chaonan Fan,Hua Dong,Cui Wang,Yuanyuan Lu,Richard J. Deckelbaum,Kemin Qi
Summary Background & aims The catabolic pathways of n-3 triglyceride (TG) rich particles (n-3 TGRP) have not been clearly elucidated. In this study, we investigated the effects of lipoprotein lipase (LPL) on the catabolism of n-3 TGRP compared to n-6 TGRP in vivo and in vitro, and we determined whether particle size affects the biological functions of LPL in n-3 TGRP catabolism. Methods Four types of lipid emulsions , chylomicron (CM)-sized n-3 TG and n-6 TG emulsions, and very low density lipoprotein (VLDL)-sized n-3 TG and n-6 TG emulsions, were labeled with 1,1′-dioctadecy1-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate (DiI) and administered via a bolus injection to LPL gene knockout (LPL+/−) mice in vivo and were added to cultured LPL miRNA-transfected 3T3-L1 adipocytes in vitro. Results With CM-sized emulsions, a reduction in LPL expression in LPL+/− mice had almost no effect on tissue uptake of n-3 TG emulsions with smaller changes in their initial blood clearance ; however, greater effects were observed for VLDL-sized n-3 TG emulsions with respect to tissue uptake with greater changes in their initial blood clearance, compared to n-6 TG emulsions with the same size. In vitro, LPL miRNA transfection had smaller effects on CM-sized and greater effects on VLDL-sized n-3 TG emulsions, with respect to particle uptake, cell TG mass, particle-cell binding and particle lipolysis . Conclusion These results suggested that LPL is more important for catabolism of n-3 TGRP of smaller size; whereas it is essential for catabolism of all sizes of n-6 TGRP.
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THERMOCHIMICA ACTA
·
2014
·
IF 2.105
Zhenjin Fu,Lin Su,Jing Li,Ruizhuang Yang,Zhanwen Zhang,Meifang Liu,Jie Li,Bo Li
The elastic silicone/ n -hexadecyl bromide microcapsules were prepared as novel microencapsulated phase change materials by microfluidic approach with the co-flowing channels, where the double oil1-in-oil2-in-water (O1/O2/W) droplets with a core–shell geometry were fabricated. The thermal characterizations of the microcapsules were investigated using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The DSC results showed that the microcapsules had good energy storage capacity with melting and freezing enthalpies 76.35 J g −1 and 78.67 J g −1 , respectively. The TGA investigation showed that the microcapsules had good thermal stability. The surfaces of microcapsules were smooth and the cross sections were compact from the results of optical microscope and scanning electron microscopy (SEM). Optical microscope showed that the silicone shell can provide expansion place due to its elastic property. Therefore, the silicone/ n -hexadecyl bromide microcapsules showed good potential as thermal regulating textile and thermal insulation materials.
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