MOLECULES
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2020
·Vol. 25
·期 9
·2109
·
IF 3.267
Changzhou Chen,Peng Liu,Haihong Xia,Minghao Zhou,Jiaping Zhao,Brajendra K. Sharma,Jianchun Jiang
It is of great importance to explore the selective hydrogenolysis of β-O-4 linkages, which account for 45–60% of all linkages in native lignin, to produce valued-added chemicals and fuels from biomass employing UV light as catalyst. TiO2exhibited satisfactory catalytic performances in various photochemical reactions, due to its versatile advantages involving high catalytic activity, low cost and non-toxicity. In this work, 20 wt.% Ni/TiO2and oxidant PCC (Pyridinium chlorochromate) were employed to promote the cleavage of β-O-4 alcohol to obtain high value chemicals under UV irradiation at room temperature. The Ni/TiO2photocatalyst can be magnetically recovered and efficiently reused in the following four consecutive recycling tests in the cleavage of β-O-4 ether bond in lignin. Mechanism studies suggested that the oxidation of β-O-4 alcohol to β-O-4 ketone by oxidant PCC first occurred during the reaction, and was followed by the photocatalysis of the obtained β-O-4 ketone to corresponding acetophenone and phenol derivates. Furthermore, the system was tested on a variety of lignin model substrates containing β-O-4 linkage for the generation of fragmentation products in good to excellent results.Keywords:lignin;β-O-4;photocatalyst;Ni/TiO2;oxidant PCC
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2020
·Vol. 31
·期 5
·3890-3898
·
IF 2.22
Liang Yue,Liu Lizhu,Zhang Wenlong,Weng Ling,Hu Deshuai,Li Chunyu
Polypropylene (PP) is considered to be a potential eco-friendly cable insulation material. However, space charge accumulation in PP under high electric stress limits its application for HVDC cable. In this paper, PP was modified with 4-acetoxystyrene (AOS) by melt grafting to improve electric properties. The molecular structure of the polypropylene-graft-4-acetoxystyrene (PP-g-AOS) was characterized by means of Fourier Transform Infrared Spectroscopy (FT-IR). The effects of temperature, screw speed, time, initiator content and monomer content on grafting degree of PP-g-AOS were investigated. Furthermore, the influence of grafting degree of PP-g-AOS on space charge suppression, volume resistivity and dc breakdown field strength was investigated. The FT-IR result showed that AOS was successfully grafted onto PP. It was found that under the proper grafting conditions, the obtained PP-g-AOS exhibited a maximum grafting degree of 1.31%. Moreover, PP-g-AOS with grafting degree of 1.14% can suppress space charge efficiently, and increase both volume resistivity and dc breakdown strength. This provides a new idea for the study of polypropylene HVDC cable insulation.
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JOURNAL OF MEMBRANE SCIENCE
·
2020
·
IF 7.183
Shushan Yuan,Gang Zhang,Junfeng Zheng,Pengrui Jin,Junyong Zhu,Jie Yang,Suilin Liu,Peter Van Puyvelde,Bart Van der Bruggen
Macrocycles have received increasing attention for the design of thin-film composite (TFC) membranes with unprecedented separation performance due to the well-defined intramolecular cavities. Herein, a macrocycle, tetra-C-ethyl resorcin[4]arene (RA), was synthesized as a novel monomer , to prepare entirely RA-based TFC membranes via interfacial polymerization. The cavities of RA macrocycles thereby act as the homogeneous intramolecular pores of the membrane for water transport and salt rejection. However, the intermolecular pores formed by gaps between RA macrocycles are random, resulting in a wide pore size distribution and average nanofiltration performance. Therefore, a very small amount of crosslinked polyamide was introduced in the gaps to tune the intermolecular pores of the membrane by adding trace amounts of piperazine (PIP) in the aqueous solution. As a result, the optimal membrane has a water permeability as high as 42.3 L m -2 h -1 bar -1 with a Na 2 SO 4 rejection of 96.5%, which is much larger than the pristine membrane without incorporating polyamide networks. This facile way of modifying the intermolecular pores gives the membrane an encouraging improvement of the performance in nanofiltration.
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ACS Omega
·
2021
·
IF 3.512
Jiawei Sun,Min Li,Xueyan Sun,Lu Wang,Peng Han,Guicun Qi,Dali Gao,Lijing Zhang,Shengyang Tao
The integral catalytic impeller can simultaneously improve reaction efficiency and avoid the problem of catalyst separation, which has great potential in applying heterogeneous catalysis. This paper introduced a strategy of combining electroless copper plating with 3D printing technology to construct a pluggable copper-based integral catalytic agitating impeller (Cu-ICAI) and applied it to the catalytic reduction of 4-nitrophenol (4-NP). The obtained Cu-ICAI exhibits very excellent catalytic activity. The 4-NP conversion rate reaches almost 100% within 90 s. Furthermore, the Cu-ICAI can be easily pulled out from the reactor to be repeatedly used more than 15 times with high performance. Energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy characterizations show that the catalyst obtained by electroless copper plating is a ternary Cu-Cu2O-CuO composite catalyst, which is conducive to the electron transfer process. This low-cost, facile, and versatile strategy, combining electroless plating and 3D printing, may provide a new idea for the preparation of the integral impeller with other metal catalytic activities.
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Reaction Chemistry & Engineering
·
2021
·Vol. 6
·期 12
·2259-2265
·
IF 4.239
Zhou Lan,Yangcheng Lu
A strategy of dissolving chlorine gas in 1,2-dichloroethane as the chlorine source for a liquid–liquid two-phase chlorination reaction was proposed in this study to resolve the problems of low efficiency, strong corrosivity, and poor controllability of traditional gas–liquid chlorination. Taking the chlorination reaction of 4-nitroaniline to synthesize 2,6-dichloro-4-nitroaniline as an example, the feasibility of the liquid–liquid chlorination method was verified in a microflow system. It can achieve 98.3% conversion and 90.6% selectivity within 1.6 s under the optimized reaction conditions. The recycling of HCl and 1,2-dichloroethane solvents was facile, and after three runs of recycling the chlorination reaction can still maintain good conversion and selectivity. The influence of feed mixing and the reaction networks on chlorination of 4-nitroaniline were also explored as a guide for process design. Compared with the traditional gas–liquid chlorination, the reaction efficiency of liquid–liquid two-phase chlorination is greatly improved, and it has a prospect for industrial application in terms of safety and controllability.
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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 18
·7028-7034
·
IF 3.069
Weitao Xu,Ming Liu,Mary Clare Escaño,Carl Redshaw,Bing Bian,Ying Fan,Zhu Tao,Xin Xiao
The interaction between cucuribit[10]uril (Q[10]) and a series of 4-pyrrolidinopyridinium salts bearing aliphatic substituents at the pyridinium nitrogen, namely 4-(C4H8N)C5H5NRBr, where R = Et (g1), n-butyl (g2), n-pentyl (g3), n-hexyl (g4), n-octyl (g5), n-dodecyl (g6), has been studied in aqueous solution by 1H NMR spectroscopy, electronic absorption spectroscopy and mass spectrometry. The results revealed that the guests g1–g5 are located completely inside the cavity differing only in the orientation of g1, g4 and g5 which are aligned with the portal, whilst g2 and g3 are perpendicular to it. For g6, the tetrahydropyrrole moiety remains outside of the portal. DFT calculations confirm the stability of the guests in the Q[10] and the possibility of their curved structure inside the Q[10].
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2019
·
IF 2.931
Fanyong Yan,Yingxia Jiang,Xiaodong Sun,Tengchuang Ma,Liang Chen,Li Chen
A sensitive and selective nanoprobe for detection of hypochlorite (OCl – ) based on 4-aminoantipyrine (AAP) modified carbon dots (CDs-AAP) has been prepared. The CDs-AAP exhibit an emission peak at 484 nm when the excitation wavelength is 370 nm, accompanying 36 nm red shift compare with the pristine CDs. The addition of OCl – lead to the AAP on the surface of CDs experience a process of hydrazide hydrolysis and double bond addition, causing the singlet and triplet electrons of the excited state more closer in energy (ie, the energy difference between the two is reduced), eventually quenching the fluorescence of CDs due to heavy atomic effects. Central composite design (CCD) and response surface method (RSM) were used to optimize the detection variables of pH, incubation time and temperature. The designed model study indicated that the optimum detection conditions was pH 7.0, temperature 30 °C and incubation time 20 min, respectively. Under optimal conditions, the fluorescent intensity of the nanoprobe linearly responded to the OCl – concentration from 3 μM to 36 μM and the limit of detection was 40 nM. The proposed nanoprobe was successfully used to the detection of OCl – in tap water and pool water, and the recovery were in the range of 94% – 103%. In addition, the nanoprobe was also applied in imaging of VMSCs cells and labeling E.coli .
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Nano Energy
·
2019
·
IF 15.548
Shu-qi Yang,Peng-bo Wang,Han-xin Wei,Lin-bo Tang,Xia-hui Zhang,Zhen-jiang He,Yun-jiao Li,Hui Tong,Jun-chao Zheng
Li-rich Mn-based cathode materials are regarded as promising cathode materials for Li-ion batteries (LIBs) owing to their high electrochemical capacity and low cost. However, residual Li compounds on the surface and dissolution of metal ions cause severe degradation of the electrochemical performance, thereby hindering their practical applications. Li 4 V 2 Mn(PO 4 ) 4 is a composite cathode material with three-dimensional Li-ion diffusion channels and a stable structure at high operating voltages (>4.5 V). Herein, we modify the surface of Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 with Li 4 V 2 Mn(PO 4 ) 4 . The Li 4 V 2 Mn(PO 4 ) 4 coating layer can not only reduce the content of residual Li compounds on the surface but also restrain the dissolution of transition metals. Theoretical calculations illustrate that Li 4 V 2 Mn(PO 4 ) 4 reduces the Li-ion diffusion energy barrier and provides efficient diffusion pathways. Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 @Li 4 V 2 Mn(PO 4 ) 4 compounds deliver a discharge capacity of 300 mAh g −1 with a high initial coulombic efficiency (84.2%) and an excellent cycling stability (capacity retention of 78.1% after 200 cycles at 1C). Hence, the proposed modification strategy of phosphate-based materials could shed light on the structural design of surface-sensitive electrode materials for LIBs.
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JOURNAL OF RAMAN SPECTROSCOPY
·
2018
·Vol. 49
·期 8
·1395-1401
·
IF 2.879
Caiqing Ma,Yu Liu,Jing Wang,Shiwei Wu,Qian Zhang,Peng Song,Lixin Xia
The coupling reaction of 4-nitrothiophenol to 4,4′-dimercaptoazobenzene was investigated by surface enhancement Raman scattering method. The reaction was found to be controlled by the compatibility of organic alkalis and silver nanoparticles. The effect of hot electron–hole pairs on the reaction was evaluated. Furthermore, the mechanism of organic alkalis affecting hot electron–hole pairs to achieve regulation of the coupling reaction of 4-nitrothiophenol to 4,4′-dimercaptoazobenzene was studied. A comprehensive analysis of the different surface enhancement Raman scattering signals collected was conducted. The forward-looking view of capturing holes through the hydrolysis of organic alkalis to ensure the integrity of the substrate was also presented.
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NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 20
·16814-16822
·
IF 3.201
Wei Huang,Shucheng Liu,Jinxin Liu,Wenli Zhang,Jianming Pan
A facile strategy to fabricate crown ether (2-methylol-12-crown-4, 2M12C4) immobilized porous polymers (PGMA-CE) was reported toward lithium(I) (Li+) recovery. Macroporous polymer foam (polymeric glycidyl methacrylate, PGMA) with abundant epoxy groups was firstly prepared as a support using a high internal phase emulsion (HIPE) template. And then 2M12C4 was covalently attached onto the surface of PGMA to endow the PGMA-CE with good stability and high selectivity. PGMA-CE was characterized by SEM, FT-IR, XPS, and 13C NMR spectroscopy, and its porous structure and the successful introduction of 2M12C4 were confirmed. In batch mode experiments under optimum conditions, PGMA-CE exhibited fast adsorption kinetics (the equilibrium time was 3.0 h), and the kinetics data were well described using a pseudo-second-order model. A Langmuir-type monolayer adsorption was investigated, and the calculated maximum equilibrium adsorption capacity was 3.15 mg g−1. In addition, PGMA-CE displayed excellent selectivity for Li+ in the presence of multiple interfering ions (Na+, K+, Mg+, and Ca2+), and the selective separation factors (α) were above 4.75. Regeneration analysis showed that the adsorption capacity of PGMA-CE toward Li+ after five cycles was 91.8% of the first cycle.
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Nanoscale Research Letters
·
2014
·Vol. 9
·期 1
·1-8
·
IF 2.481
Gao Zhao,Su Rongxin,Huang Renliang,Qi Wei,He Zhimin
A facile one-pot approach for synthesis of gold nanoparticles with narrow size distribution and good stability was presented by reducing chloroauric acid with a polysaccharide, konjac glucomannan (KGM) in alkaline solution, which is green and economically viable. Here, KGM served both as reducing agent and stabilizer. The effects of KGM on the formation and stabilization of as-synthesized gold nanoparticles were studied systematically by a combination of UV-visible (UV-vis) absorption spectroscopy, transmission electron microscopy, X-ray diffraction, dynamic light scattering, and Fourier transform infrared spectroscopy. Furthermore, the gold nanoparticles exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2013
·
IF 3.172
Qiongbo Zhou,Ding Gao,Jun Liu,Xuzhuo Sun,Lei Zhang,Bin Qi,Haibo Zhang,Chunlan Xia,Xiaohai Zhou
Spontaneous formation of supramolecular vesicles which are triggered by the formation of [4]pseudorotaxane B was demonstrated, whereas both Guest and [2]pseudorotaxane A, the precursors of [4]pseudorotaxane B, only assemble into micelles in DMF/water solution. The remarkable transformation of Guest from micelles to supramolecular vesicles was confirmed through DLS , TEM , and Cryo-TEM experiments. The cumulative release of a model drug, 5-carboxyfluorescein (CF), was used to determine the permeability of the supramolecular vesicles. No leakage of entrapped CF was observed within 48 h by fluorescence measurement, indicating the high stability of supramolecular vesicles. The formation mechanism of supramolecular vesicles self-assembled by [4]pseudorotaxane B was also discussed. In [4]pseudorotaxane B, CB[6] is used to increase the hydrophobic property of site β , which acts as hydrophobic “tail.” Meanwhile, CB[7] plays the role of increasing “head area” of site α , which acts as hydrophilic “head.” The synergistic effect of CB[6] and CB[7] induces the formation of supramolecular vesicles. Moreover, the effect of DMF content was investigated by TEM observations. It was found that the [4]pseudorotaxane B can self-assemble into regular supramolecular vesicles when the DMF content is in the range of 50–70%.
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