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10 August 2017, Volume 38 Issue 8

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Cover and Content of Chemical Journal of Chinese Universities Vol.38 No.8(2017)

2017, 38(8):  0-0. 

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Articles: Inorganic Chemistry

Facile Synthesis of ZIFs-derived Hollow Bimetal (Zn,Co)S Nanocrystals for Supercapacitors

CHENG Wei, CHEN Cailing, YU Ying, LI Chunguang, GAO Lu, SHI Zhan

2017, 38(8):  1303-1308.  doi:10.7503/cjcu20170122

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A simple two-step method was introduced to synthesize uniform and hollow (Zn,Co)S nanostructures. Firstly, the bimetal compound ZIF-Zn,Co(ZIF=zeolitic imidazolate frameworks) with metal ions(Zn²⁺ and Co²⁺) and ligand(2-methylimidazole) was obtained using deionized water as solvent, hexadecyltrimethylammonium bromide(CTAB) as capping agent under stirring at room temperature. Secondy, hollow (Zn,Co)S nanostructures were synthesized by selecting ZIF-Zn,Co as self-sacrificial template and adding thioacetamide(TAA) as sulfate source under the microwave-assisted heating condition. The electrochemical measurements show that the specific capacitance of the as-made hollow (Zn,Co)S nanostructures was 423.3 F/g at current density of 3 mA/cm² and 57% capacitance remains after 2000 cycles at a current density of 10 mA/cm². With the advantages of unique properties, such as high surface area and good electrochemical performance, the as-made hollow (Zn,Co)S nanostructures have great potential as electrode material for supercapacitors.



Effects of Ag⁺, Sr²⁺, Yb³⁺ Dual-doping on Thermoelectric Properties of Ca₃Co₄O_9-δ

YANG Tao, CHENG Tiexin, ZHOU Guangdong

2017, 38(8):  1309-1315.  doi:10.7503/cjcu20170244

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A series of ceramic materials, Ca_3-x-yAg_xSr_yCo₄O_9-δ, Ca_3-x-zAg_xYb_zCo₄O_9-δ and Ca_3-y-zSr_yYb_zCo₄O_9-δ(x, y, z=0.1, 0.15, 0.2) which worked from 300 K to 870 K with excellent thermoelectric properties, was prepared by sol-gel and cold-pressing method. The XRD, IR and SEM results reveal that the prepared samples are uniform crystal particles with high purity. Ag⁺, Sr²⁺ and Yb³⁺ ions have replaced the position of Ca²⁺ ions and they are dissolved in the crystal, which changes the cell volume of the dual-doping materials but does not change the crystal symmetric structure. The characterization results of resistivity and Seebeck coefficient reveal that the concentration of carrier is optimized by dual doping, accordingly the resistivity decreases continuously with the doped different materials and the value of Seebeck coefficient increases continuously with the doped different materials. It can be concluded from the calculations that the electron effective mass contributes to the increase of Seebeck coefficient. The characterization results of thermal conductivity indicate that the thermal conductivity of dual doped samples decreases with the increase of temperature, and the phonon thermal conductivity still contributes more in the prepared system, which is consistent with the results of Ag⁺, Sr²⁺, Yb³⁺ single doped Ca₃Co₄O_9-δ samples. The figure of metrt ZT of Ca_2.7Ag_0.2Yb_0.1Co₄O_9-δ exceeds 0.18 at 870 K.



Preparation and Arsenic Removal Mechanism of Iron Oxyhydroxide/expanded Graphite Composite Material

JIAO Chunlei, XU Congbin, LI Shuyan, YANG Wenjie, SUN Hongliang, LIU Weijiang, JIAO Zhenhuan, LIN Aijun

2017, 38(8):  1316-1323.  doi:10.7503/cjcu20170062

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Iron oxyhydroxide/expanded graphite composites were prepared via surface grafting under the environment of acid and ultrasonic oscillations, with expanded graphite as carrier material and iron oxyhydroxide(FeOOH) prepared as the modifier. Scanning electronic microscopy(SEM), X-ray diffraction(XRD) X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR) techniques were employed to characterize the composite. Then the removal performance of arsenic by the composite was determined. The results show that the iron oxyhydroxide loaded on the surface of expanded graphite evenly as the sub-micron spherical by hydrogen bond and chemical bonds. The removal rate of arsenic can reach 99% using 0.5 g composite to treat 50 mL simulated waste water containing 0.5 mg/L arsenic after 90 min, and the treated waste water can reach the drinking standard. The removal rate of arsenic by the composite improves with the increase of iron content in the composite, and when the iron content in the composite reaches 55%, the removal rate of arsenic can reach 72.6% using 0.5 g composite to treat 50 mL simulated waste water containing 2.0 mg/L arsenic within 60 min, three times as high as that of ordinary expanded graphite. In addition, the dissociated iron oxyhydroxide reacts with arsenic in the vicinity of the composite material and the removal process of arsenic confirms to the secondary dynamics equation and Temkin isotherm adsorption model.



Extraction of Am(Ⅲ) and Eu(Ⅲ) from Nitric Acid Solution with the Pyridylpyrazole Based Ligand C8-BPP

HU Xiaoyang, SU Dongping, LI Shimeng, WANG Zhipeng, ZHANG Lirong, LIU Ying, SONG Lianjun, CHEN Zhili, DING Songdong

2017, 38(8):  1324-1333.  doi:10.7503/cjcu20170027

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Pyridylpyrazole based ligand 2,6-bis[5-(n-octyl)-1H-pyrazol-3-yl] pyridine(C8-BPP) was synthesized and characterized by means of mass spectrometry(MS), nuclear magnetic resonance(NMR) spectrometry, and Fourier transform infrared spectrometry(FTIR). In the presence of 2-bromohexanoic acid, using n-dodecane as diluent, the extraction behaviors of Am³⁺ and Eu³⁺ with C8-BPP were investigated. Influences of diluent, contact time, acidity and the ligand concentration on the extraction of Am³⁺ and Eu³⁺ were evaluated in HNO₃ solution. The distribution ratio values of Am³⁺ and Eu³⁺ decreased with increasing HNO₃ concentration from 0.2 to 1.0 mol/L, and increased with increasing ligand concentration from 0.01 to 0.1 mol/L. With the increase of acidity, the separation factors(SF_Am/Eu) increased firstly and then decreased. The maximum value of SF_Am/Eu can reach 55 at 0.5 mol/L HNO₃. Meanwhile, SF_Am/Eu values decreased slowly with increasing the ligand concentration but all the SF_Am/Eu values were above 40. The extraction results also showed that C8-BPP exhibited good selective extraction ability for Am³⁺ over RE³⁺. Moreover, slope analyses indicated the formation of 1:1 complexes of C8-BPP with Am³⁺ and Eu³⁺, separately. Besides, the complexation behaviors of C8-BPP with Eu³⁺ were also investigated by means of UV-Vis spectrometry titration, electrospray ionization mass spectrometry(ESI-MS), FTIR, Raman spectrometry and time-resolved laser-induced fluorescence spectroscopy(TRLFS). The composition and stability constant(lgK) of the complex of C8-BPP with Eu³⁺ were also obtained.



Analytical Chemistry

Cytosine-rich Oligonucleotide-templated Fluorescent Silver Nanoclusters for Sensitive Assay of S1 Nuclease

WANG Xingxing, LI Panpan, HE Jinglin, OUYANG Wen, XIAO Hui, YANG Chan, CAO Zhong

2017, 38(8):  1334-1340.  doi:10.7503/cjcu20170113

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A label-free fluorescence method for detection of S1 nuclease was developed using oligonucleotide-templated silver nanoclusters(AgNCs). Cytosine-rich single strand DNA(C-rich ssDNA) scaffolded silver nanoclusters were devised and synthesized as a functional probe. S1 nuclease can specifically recognize ssDNA, which is degraded into mononucleotide and oligonucleotide fragment under the optimum enzyme-catalyzed reaction condition. In the absence of S1 nuclease, the silver nanoclusters could be effectively synthesized by C-rich ssDNA, which produced obvious fluorescence intensity. In the presence of S1 nuclease, C-rich ssDNA probes were specifically recognized and effectively digested into small fragments. As a result, the silver nanoclusters synthesis was suspended leading a fluorescence reduction. A good linear correlation was obtained between fluorescence change and the logarithm of the Cu²⁺ ions concentration over the range from 5.0×10^-5 U/μL to 4.0×10^-3 U/μL. The detection limit was estimated as 2.0×10^-6 U/μL. The proposed method was highly selective and there were no obvious interfering effects on the determination from Bst polymerase, Thrombin, ExoⅢ, E.coli ligase and BSA. The proposed sensor reveals good recovery rates from 91.8% to 109.5% in RPMI 1640 cell medium, indicating that the sensing system was feasible for the detection of S1 nuclease in practical samples. This label-free, simple and cost-effective strategy has a potential application in biomedical research and clinical early diagnosis.



Interaction Between 5-Furd and Cu,Zn-SOD1 by Ion Mobility Mass Spectrometry and Fluorescence Spectroscopy

ZHAO Bing, ZHUANG Xiaoyu, LIU Shu, ZHENG Zhong, LIU Zhiqiang, SONG Fengrui

2017, 38(8):  1341-1346.  doi:10.7503/cjcu20170103

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The interaction between 5-Furd and Cu, Zn superoxide dismutase(SOD1) was investigated by means of electrospray-ion mobility mass spectrometry(ESI-IMS-MS) and fluorescence spectroscopy. The result of ESI-IMS-MS showed that 5-Furdis could stabilize the conformation of SOD1 against unfolding transition at different collision voltages. Through the ThT fluorescence method, it was further testified that 5-Furd could inhibit the aggregation of apo-SOD1. In addition, the interaction between SOD1 and 5-Furd at different temperatures was investigated by fluorescence spectrometry, and the characters of their interaction were elucidated including the interaction mechanism, the binding constant, binding site number and the corresponding thermo-dynamic parameters(△H, △S and △G). According to the thermo-dynamic parameters of interaction, it was found that the hydrophobic forces play an important role on their interaction.



Ultrasensitive Detection of Malachite Green Using the Coupling Technique of Dummy Molecular Imprinting and Surface-enhanced Raman Scattering

MA Fangchen, LI Xin, REN Xiaohui

2017, 38(8):  1347-1353.  doi:10.7503/cjcu20170047

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The coupling technique of molecular imprinting with surface enhanced Raman scattering is regarded as a promising analysis method due to its properties of high sensitivity and selectivity. However, the traditional molecular imprinting technique is very difficult to thoroughly remove template molecules. So, the technique will result in strong background interference impacting the test results when it is combined with the surface-enhanced Raman scattering spectroscopy. In this study, the Ag particles were first synthesized adopting the method of ascorbic acid reduction. Then, the as-prepared Ag particles were silanized using 3-methacryloxypropyltrimethoxysilane. Finally, the dummy molecularly imprinted polymers were synthesized using abietic acid replacing malachite green as the template molecule to react with methacrylamide functional monomer. The results show that the resulting "core-shell" composite substrate has a more remarkable SERS enhancement than Ag substrate. And its detection limit for malachite green can down to 10^-11 mol/L. This method can eliminate the background interference and improve the accuracy of the analysis results, which provide a new method for the ultrasensitive detection of organic dyes.



Organic Chemistry

Characterization of the Interaction Between Esterified TAM Radical and Bovine Serum Albumin

AN Pengjiao, YU Nannan, SUN Ruisheng, SUI Xiaofang, SONG Yuguang

2017, 38(8):  1354-1361.  doi:10.7503/cjcu20170203

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Fully substituted tetrathiatriarylmethyl(TAM) radicals and their derivatives are ideal electron paramagnetic resonance(EPR) spectroscopy/imaging probe and have been received much concern in NMR contrast agent or spin traps fields. This work demonstrated that an esterified TAM radical(ET-03) bound to bovine serum albumin(BSA) in aqueous solution with fluorescence, electron paramagnetic resonance(EPR) spectroscopy, UV-Vis spectroscopy and molecular docking. The results showed that ET-03 spontaneously bound to BSA. The binding between ET-03 and BSA was driven by a hydrophobic interaction and the binding site was mainly determined to be the sub-domain ⅡA(Sudlow's site Ⅰ) and the sub-domain ⅢA(Sudlow's site Ⅱ). The fluorescence quenching of BSA by ET-03 was a mixture of static and dynamic mechanism with energy transfer probably. This protein binding of the esterified TAM probe to albumin can be used to study the structure and function of albumin and also must be considered for its use as an in vivo imaging agent or spin label.



Cascade Biodegradation of Organic Pesticide Isoproturon

WANG Fengjiao, LI Xuelian, HU Mancheng, LI Shuni, ZHAI Quanguo, JIANG Yucheng

2017, 38(8):  1362-1367.  doi:10.7503/cjcu20170055

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Cascade biodegradation of organic pesticide isoproturon by enzymatic oxidation and activated sludge treatment is presented in this work. An enzymatic approach for the degradation of pesticide isoproturon catalyzed by chloroperoxidase with H₂O₂ as oxidant was proposed firstly. The complete degradation efficiency was achieved within 10 min at pH=3.0 and room temperature. The required H₂O₂ concentration was 0.2 mmol/L, and the dosage of chloroperoxidase(CPO) was only 7 nmol/L, indicating very few enzyme was required. The proposed degradation method was very efficient, mild, environment-friendly and no second pollution was involved, ensuring a potential application. The degradation products of isoproturon by CPO were determined by HPLC-MS, and the degraded route was proposed accordingly. Isoproturon was decomposed into small molecule 4-isopropyl aniline and 4-ethyl aniline benzylic cation by CPO-H₂O₂ catalytic oxidation. If the CPO-H₂O₂ was used as pre-stage treatment and was combined with activated sludge, the chemical oxygen demand(COD) can be eliminated to achieve effective decontamination of waste water containing isoproturon. Moreover, the ecotoxicity test using a green algae, Chlorella pyrenoidosa, showed that the growth inhibition ratio decreased with the increase of degradation of efficiency of isoproturon, indicating that the degraded products had lower toxicity than the parent isoproturon molecule.



Detection of Animal Tissue Distribution of β-1,3/1,6-Glucan from Durvillaea antarctica by in vivo Imaging

ZHAO Xiaoliang, LIU Xi, YANG Yi, CAI Chao, LÜ Youjing, LI Guoyun, HAO Jiejie, YU Guangli

2017, 38(8):  1368-1374.  doi:10.7503/cjcu20170127

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In the present study, β-1,3/1,6-glucan(DAG) from Durvillaea antarctica was investigated. First, the functional amino group was introduced into the DAG reduction site by reductive amination reaction. The reaction product was then coupled with NHS-activated fluorescent dye(Cy7), and the Cy7-labeled DAG molecule was obtained subsequently. The distribution of DAG in mice was studied by small animal in vivo imaging technique. The results show that DAG is mainly distributed in the lungs, livers and kidneys, which possessed the characteristics of targeting the mouse lungs and excreting through the kidneys. The method is simple and reliable, which provides an important reference for the distribution and metabolism study of polysaccharides and oligosaccharides in vivo.



Synthesis, Crystal Structure and Fungicidal Activity of (Z)-3,3-Dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one O-[(5-Aryl-1,3,4-oxadiazol-2-yl)methyl] oxime

TAN Ying, XIAO Mengwu, YE Jiao, HU Aixi, ZENG Ziqing, OU Xiaoming

2017, 38(8):  1375-1382.  doi:10.7503/cjcu20170024

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A series of (Z)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one O-[(5-aryl-1,3,4-oxadiazol-2-yl)methyl] oxime(4a-4u) was designed and synthesized via the reaction between iodobenzene diacetate(IBD) and the intermediates, (E)-N'-substituted benzylidene-2-({(Z)-[3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ylidene] amino}oxy)acetohydrazide(3), which were prepared from (Z)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one oxime via etherification, hydrazinolysis and condensation with various of substituted benzaldehyde. The structures of target compounds 4 were confirmed by muclear magnetian resonance(NMR), high resolution mass spectrum(HRMS) and elemental analysis. The crystal structure of compound 4c was determined by X-ray diffraction analysis. The results of fungicidal activity indicated that some of the title compounds exhibited moderate control rate against Rhizoctonia solani at 500 mg/L and moderate inhibition rate against Sclerotonia sclerotiorum at 25 mg/L.



Physical Chemistry

Theoretical Investigation on the Adsorption of Nitroglycerin on the α-Al₂O₃(0001) and γ-Al₂O₃(110) Surfaces

WANG Yanqun, WANG Baoshan, LI Wei

2017, 38(8):  1383-1389.  doi:10.7503/cjcu20170228

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Nitroglycerin(NG) and alumina were used as the models of energetic plasticizers and the surface of fuels in propellants to investigate the microscopic mechanism of interactions between materials containing nitrate ester group and combustion agent surface. First-principles calculations based on density functional theory with the all-electron double numerical polarized basis sets were employed to study the adsorption of NG on the α-Al₂O₃(0001) and γ-Al₂O₃ (110) surfaces. The results indicate that strong chemical adsorption exists between NG and the α-Al₂O₃(0001) as well as γ-Al₂O₃ (110) surfaces, which results in significant elongation and breakage of corresponding O-NO₂ bond of NG. The dissociation which produces NO₂ free radical is barrierless and releases a large amount of heat. The adsorption energy is about 175.7 kJ/mol. The interaction of NG and the fully hydroxylated surfaces comes from H-bonding interactions mainly. The adsorption energy decreases significantly and is about 50.0 kJ/mol. For partly hydroxylated surfaces, it is found that both chemical and physical adsorption would occur on the surfaces and no obvious synergy or catalysis exist for both mechanisms. The present theoretical work is useful to gain some new insights on the compatibility of materials containing nitrate ester group and the other components in propellants.



Ab initio Calculation and Kinetic Investigation of Monacid-catalyzed Decomposition of Sulfurous Acid

FANG Sheng, LIU Jingjing, DUAN Xuemei, TAO Fuming, LIU Jingyao

2017, 38(8):  1390-1398.  doi:10.7503/cjcu20170162

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The mechanism of decomposition of sulfurous acid to sulfur dioxide and water catalyzed by formic acid, acetic acid, propionic acid and nitric acid, respectively, was investigated by ab initio calculations at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level of theory herein. The computational results showed that all the four acids presented catalytic effect for the decomposition of sulfurous acid. The reduction extent of the energy barrier was in the order propionic acid > acetic acid > formic acid > nitric acid. Furthermore, the energy barrier of propionic acid-catalyzed reaction decreased dramatically from 99.84 kJ/mol of naked reaction to 27.24 kJ/mol. The rate constants of the catalyzed reactions in the temperature range of 200-320 K had been calculated. In addition, the effective rate constants were also calculated in combination with the atmospheric concentrations of these acids. The results indicated that the acetic acid had the most effective catalytic effect in the atmospheric environment, and the lifetime of sulfurous acid was only 0.02 s with the appearance of acetic acid.



Effect of Branched Hydrophobic Group on the Surface Dilational Rheology of Betaine Surfactants

GUO Lanlei, ZHU Yangwen, XU Zhicheng, GONG Qingtao, JIN Zhiqiang, ZHANG Lei, ZHANG Lu

2017, 38(8):  1399-1405.  doi:10.7503/cjcu20170050

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The surface dilational rheological properties ofisomeric compounds, straight chain(C₁₆PB) and branched chain(C₁₆GPB) hexadecyl hydroxypropyl carboxybetaines were investigated by drop shape analysis. The influences of ageing time, surface pressure, dilational frequency and bulk concentration on surface dilational modulus and phase angle were expounded. It is found that the whole hydrophilic part of betaine molecule inclines to flat on the surface when betaine adsorbs, which will lead to higher dilational modulus. The nature of adsorption film is determined by in-surface processes, such as the variation of orientation of hydrophilic group. The branched hydrophobic alkyl chains of betaine molecules improve the intermolecular interactions, not only results in higher moduli, but causes a maximum in dynamic modulus at high betaine concentration. This result indicates that the strength of surface film is strongly related to molecular arrangement, not simply determined by the surface molecule concentration.



Mechanism Research of Reactions of Metal Carbides and Carbenes Cation[M-X] ⁺(M=Au, Ag, Cu; X=C, CH₂) with Methane

SUN Xiaoli, MENG Lingmin, JIN Mingxing, LI Jilai

2017, 38(8):  1406-1414.  doi:10.7503/cjcu20170039

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In this article, the reaction mechanism of the cation[Au(CH₂)] ⁺ and methane was investigated at the CCSD(T)-REL//B2GP-PLYP level of theory initially. A detailed analysis of geometric structure changes during the C-H bond activation was given. As a major result, based on natural bond orbital(NBO) charge and molecular orbital analysis, a hydride transfer mechanistic scenario from methane to[Au(CH₂)] ⁺ was identified unambiguously. Methane activation has been identified among its reaction with[M-X] ⁺(M=Au, Ag, Cu; X=C, CH₂). Analysis for the inherent factors during the reaction of methane as a hydrogen donor is given. The M-X bond energy and the low-lying vacant orbital directly involved in the reaction of the active center C play an important role on the reaction activity, and both mediated microscopic mechanism. This study may provide important guidance for the rational design of catalysts.



Nitrate Removal by Expanded Graphite Loaded with Zero-valent Iron:Performance and Mechanism

XU Congbin, ZHANG Li, YANG Wenjie, SUN Hongliang, LIU Weijiang, JIAO Zhenhuan, JIAO Chunlei, LIN Aijun

2017, 38(8):  1415-1422.  doi:10.7503/cjcu20170036

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Zero-valent iron(ZVI) loaded onto expanded graphite(EG) as a composite material(EG-ZVI) was prepared through chemical deposition method to remove nitrate. The EG/ZVI was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). It is observed that the EG was successfully loaded with sub-micron scale zero-valent iron. Batch experiments with variable theoretical ZVI mass loading, pH values and temperature were conducted to evaluate the removal performance of EG-ZVI. The results showed that the removal rate of nitrate was 2.3 times higher than that for EG. Furthermore, the removal of nitrate by EG-ZVI shows little dependence on solution pH. Even at pH=9, the nitrate removal efficiency could attain 65% after reaction for 90 min. Galvanic cell effect and high specific surface area are the main reasons for the enhanced removal of nitrate by EG-ZVI with chemical reduction and physical adsorption. And third-order kinetic model is well fitted. XPS were used to analyze the mechanisms of nitrate removal, which indicated that ZVI loaded on the surface was oxidized, and the removed nitrate was reduced to NH₄⁺-N and NO₂^--N. In addition, EG-ZVI could overcome the shortcomings of ZVI which formed undesirable precipitation of ferrous hydroxide on the surface during reaction frequently. High removal capability, excellent stability and broad applicability make EG-ZVI ideal candidates for nitrate removal in practical application.



Synthesis of Ordered Mesoporous Fe-N-C-PANI Catalyst via Self-assembly and Its Oxygen Reduction Reaction Activity in Acid Medium

KANG Huan, LI Shang, LIU Chang, GUO Wei, PAN Mu

2017, 38(8):  1423-1430.  doi:10.7503/cjcu20160941

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Highly ordered mesoporous Fe-N-C-PANI electrocatalysts were synthesized by ethanol evaporation induced self-assembly using triblock copolymer Pluronic F127 as template, phenol-formaldehyde resin as carbon precursor and polyaniline as the N precursor. XRD, TEM, BET, XPS and RDE techniques were used to characterize the composition, morphology and electrocatalytic activity of the catalysts. The results show that the catalyst pyrolyzed at 800℃ has distinctly ordered mesoporous structure and straightest channel, and its speci-fic surface area is as high as 1007 m²/g. The results of XPS show that the percentage of pyidinic N and Graphitic N of Fe-N-C-PANI-800 is 3.86%(molar fraction). In the process of heat treatment, Fe(Ⅲ) was reduced to metallic Fe, and the introduction of N was facilitated, which made iron carbide turn into Fe-N_x active sites, and enhanced the ORR catalytic performance of catalysts. But when the temperature rise to 900℃, the formation of metallic Fe decreases its ORR activity. In the acid medium, Fe-N-C-PANI-800 has an onset potential of 0.89 V(vs. RHE) and a half-wave potential of 0.81 V(vs. RHE). Ordered mesoporous catalyst had higher graphitization structure, which improved its stability.



Catalytic Cracking of n-Hexadecane

SUN Chuanyin, WANG Ying, WANG Runwei, QIU Shilun, ZHANG Zongtao

2017, 38(8):  1431-1435.  doi:10.7503/cjcu20160928

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A new kind of hierarchical ZSM-5 zeolite catalyst with hollow and thin shell structure was synthesized and tested by cracking of n-hexadecane to study its pore effect and acid properties. The results showed that this zeolite catalyst had better catalysis activity and prolonged life because of its improved molecular diffusion brought by its mesopores and macropores. In addition, large amount of acid sites on the hierarchical pores can be more beneficial to large molecular reactions and get better product selectivity. This structure-activity relationship is more obvious especially on short contact time conditions. In a word, catalysts with proper activity distribution as well as hierarchical pores, hollow and thin shell structure should have better activity, product selectivity and prolonged life, which can provide the basis to design novel high-performance catalysts in the future.



Freeze-drying Synthesis and Characterization of Li₂FeSiO₄/C Cathode Materials for Lithium Ion Batteries

ZHANG Dong, LI Haoming, QIU Hailong, CHEN Gang, YUE Huijuan, LIU Anhua

2017, 38(8):  1436-1441.  doi:10.7503/cjcu20160925

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Li₂FeSiO₄/C nanocomposites were prepared by freeze-dying synthesis. X-ray diffraction, Raman spectrometry, field emission scanning electron microscopy and N₂ adsorption-desorption were used to investigate the effect of dry method on the physical characteristics of Li₂FeSiO₄/C. The results show that Li₂FeSiO₄ obtained by freeze-drying method(DG) exhibits smaller particle size and larger specific surface area. The electrochemical performance was studied by galvanostatic charge-discharge and electrochemical impedance spectra. Compared to the Li₂FeSiO₄ obtained by ordinary drying method(HG), DG exhibits better rate capability, and the discharge capacity of 106.7 mA·h/g can be achieved at 2C rate.



Preparation and Lithium Storage Performance of Nanostructured V₂O₅ with 0/1/2 Dimensional Hybrid Morphologies

XIE Zhiping, YAO Jinhuan, LIU Canzheng, JIANG Jiqiong, LI Yanwei

2017, 38(8):  1442-1449.  doi:10.7503/cjcu20160839

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Orthorhombic V₂O₅ nanomaterial with 0/1/2 dimensional hybrid morphologies(H-V₂O₅) was prepared by sol-gel method combined with freeze-drying technique using P123 as structure-directing agent. The microstructure and morphology of the prepared samples were analyzed by X-ray diffraction(XRD) and Scanning electron microscopy(SEM), and the lithium sto-rage performance was characterized by cyclic voltammetry(CV), constant current charge/discharge, and electrochemical impedance spectroscopy(EIS) tests. The results showed that H-V₂O₅ possessed high lithium sto-rage capacity, excellent cycling stability, and outstan-ding high rate capability. When cycled at a constant current density of 1 A/g, the H-V₂O₅ delivered a stable discharge capacity of 117.5 mA·h/g after 500 cycles, corresponding to capacity retention of 94.4%; even at a very high current density of 5 A/g, the H-V₂O₅ still showed a discharge capacity of 88.2 mA·h/g, which is much superior than that for two dimensional sheet-like V₂O₅ nanomaterial prepared without the assistance of P123.



Preparation and Synergistic Catalytic Performance of Ag/TiO₂ Composite Photocatalysts Modified by Acetic Acid

A Shan, ZHEN Jiawei, LIU Juming, BAI Jie, YANG Jucai, ZHANG Qiancheng

2017, 38(8):  1450-1457.  doi:10.7503/cjcu20160809

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Ag/TiO₂ sample was prepared by photochemical reduction approach, and then the sample was impregnated with acetic acid to obtain the HAc-Ag/TiO₂ composite photocatalysts. The samples were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS), X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared(FTIR) spectroscopy. The visible light photocatalytic degradation of methyl orange(MO) in an aqueous solution was used as a probe reaction to evaluate the photocatalytic activity of the obtained samples. It reveals that the modifying of acetic acid can obviously narrow the bandgap of TiO₂ via the formation of band tail in the bandgap of TiO₂. Especially, the co-modification of Ag and acetic acid resulted in more narrow TiO₂ bandgap and more positive top of valence band. The synergistic effects of Ag and acetic acid on TiO₂ enhanced the photocatalyst performance of HAc-Ag/TiO₂ composite. Under visible light irradiation, nearly 100% of MO was degraded within 2 h on the HAc-Ag/TiO₂ photocatalyst.



Preparation and Electrochemical Performance of Na⁺-stabilized Layered LiNi_0.6Co_0.2Mn_0.2O₂ Cathode Material for Lithium-ion Batteries

ZHENG Zhuo, WU Zhenguo, XIANG Wei, HUA Weibo, GUO Xiaodong

2017, 38(8):  1458-1464.  doi:10.7503/cjcu20160781

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Na-doped Li_0.98Na_0.02Ni_0.6Co_0.2Mn_0.2O₂ cathode material was synthesized through a simple oxalate co-precipitation. Powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), inductively coupled plasma-atomic emission spectrometry(ICP-AES), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge tests were employed to analyze the particle morphology, crystal structure and electrochemical properties of the as-prepared materials. Results indicate that the Na-stabilized sample has a more ordered α-NaFeO₂ structure(space group R3m), reduced Li⁺/Ni²⁺ cation mixing and enlarged Li layer spacing, which facilitates the fast insertion and extraction of Li⁺ ions in the bulk structure. Electrochemical results confirm that the Na-stabilized sample has excellent cycling stability and high rate performance. After 100 cycles at 1C between 2.7 V and 4.3 V, the cathode delivers a discharge capacity of 146 mA·h/g with capacity retention of 95.4%. At 0.1C, 0.2C, 0.5C, 1C, 3C, 5C, 10C and 20C, the specific capacities of the material are 181, 168, 162, 155, 143, 136, 126 and 113 mA·h/g, respectively. The Na-doping method is facile and feasible, which can provide some valuable reference for synthesizing other high rate and high capacity layered anode/cathode oxides.



Polymer Chemistry

Preparation of PVA/GA/β-CD Nanofibers and Its Adsorption of Dyestuff

LU Guanxiu, LIU Qingwen, KONG Xiangyi, CONG Lele, SONG Yan, ZHAO Qing, YANG Qingbiao, LI Yaoxian

2017, 38(8):  1465-1469.  doi:10.7503/cjcu20170142

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The polyvinylalcohol/β-cyclodextrin(PVA/β-CD) nanofibers with 70%(mass fraction) of β-CD were obtained by electrostatic spinning with hexafluoroisopropanol(HFIP) and H₂O as solvents. And after cross-linking treatment with glutaraldehyde(GA), a water-insoluble nanofiber membrane of PVA/GA/β-CD was prepared. Compared with the products before being cross-linking, composition and morphology for the nanofibers were studied by Infrared spectroscopy and scanning electron microscopy. In addition, the adsorptive properties of the PVA/GA/β-CD nanofibers to seven water-soluble dyes were investigated. The results show that the adsorptive effect of fiber on malachite green, methyl violet and congo red are better than others, and the maximum adsorptive capacities are 124.71, 121.14 and 127.39 mg/g, respectively. After four cycles of adsorption-desorption, the dye removal rate still remains 80%. Thus, the nanofiber exhibits an excellent applicative prospect in waste water treatment with dye.



Effect of Amphiphilic Silica Rods on the Morphology of Immiscible Polyisobutylene/Polydimethylsiloxane Blends Under Simple Shear Flow

YE Lishaya, HUANG Yajiang, KONG Miqiu, LOU Fangli, YANG Qi, LI Guangxian

2017, 38(8):  1470-1476.  doi:10.7503/cjcu20170102

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Silica rods with amphiphilic surface properties were synthesized and their effects on the morphology of immiscible polyisobutylene(PIB)/polydimethylsiloxane(PDMS) blends were investigated via online flow-visualization technique and rheology. Confocal laser scanning microscopy revealed that amphiphilic silica rods tended to distribute at the interface and within the PIB phase. In addition, the flow-induced coalescence behavior of droplets was found to strongly depend on the particle content and the blending composition ratio. The addition of a small amount of amphiphilic silica rods could promote the coalescence of droplets, while coalescence was suppressed effectively at high particle loadings.



Preparation and Properties of Flame Retardant Cotton Fabric by Surface Chemical Grafted Modification

LIU Ziyi, XU Miaojun, WANG Qi, LI Bin

2017, 38(8):  1477-1483.  doi:10.7503/cjcu20170032

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Cotton fabric was firstly selective oxidized by sodium periodate to formed aldehyde groups, ethylenediamine was chosen and reacted with aldehyde groups. Then, the flame retardant dimethyl phosphite was grafted on cotton fabric surface by phosphine hydride addition reaction. Finally, trimethylolmelamine was grafted on the surface of cotton fabric and the phosphorus-nitrogen containing flame retardant cotton fabric was obtained. The structure of the modified cotton fabric was characterized by Fourier transform infrared spectroscopy(FTIR). The flame retardancy of the modified cotton fabric was evaluated by limiting oxygen index(LOI) tests, and the combustion behavior was investigated by cone calorimeter tests. The water washing durability of the modified cotton fabric was investigated by washing in soap water for 10 times at 40℃, and the surface morphology was studied by scanning electron microscopy. The result indicated that the LOI value of the obtained modified cotton fabric dramatically increased from (19.5±1.0)% for pure cotton fabric to (43.1±1.0)%, and after washing test, the LOI value slightly decreased to (42.6±1.0)%, which indicated that the obtained cotton fabric remained superior flame retardancy and possessed excellent washing durability. The surface chemical grafted modification for cotton fabric enhanced the char-forming ability of cotton fabric during combustion, and the formed intumescent char layer protected the inner cotton fabric from further degradation and combustion, thus enhanced the flame retardancy of cotton fabric.



Synthesis and Properties of PS-b-P(DMS-stat-VMS) Block Copolymer

LU Zhiwei, CHEN Shun, JU Yanyun, ZHANG Yang, XIONG Chuanxi, DONG Lijie

2017, 38(8):  1484-1488.  doi:10.7503/cjcu20170014

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The active block copolymer polystyrene-block-poly(dimethylsiloxane-stat-vinylmethylsiloxane)[PS-b-P(DMS-stat-VMS)] was prepared by reactive anionic polymerization, which was advantageous for diverse chemical modifications for broad practical applications. The chemical structure, molecular weight and morphology of as-prepared copolymer were characterized by FTIR, ¹H NMR, GPC, FESEM and AFM. Meanwhile, the water/diiodomethane contact angle test was utilized to investigate the surface property of the product. The results indicated that the copolymer exhibited narrow molecular weight distribution of 1.37. Owing to the thermodynamic incompatibility between soft and hard domains, the copolymer film prepared by tape casting showed microphase separation structure, and the PDMS-PVMS soft domain was inclined to accumulate on the surface of the film. Moreover, the copolymer exhibited excellent hydrophobicity and low surface energy due to the surface enrichment of PDMS-PVMS soft domain.



Synthesis and Characterization of Injectable Hydrogels Based on Star β-CD-g-poly(L-glutamic acid)

JIAN Yuhang, YAN Shifeng, LI Xing, HUANG Yanan, YIN Jingbo

2017, 38(8):  1489-1496.  doi:10.7503/cjcu20170008

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A Gadelle-Defaye method was used to synthesis per-6-amino-β-CD[β-CD-(NH₂)₇]. Then, different molecular weighted star β-CD-g-poly(L-glutamic acid)(β-CD-g-PLGA-ADH) was synthesised via "grafting-from" method. The hydrogel precursors, β-CD-g-PLGA-ADH and oxided alginate(ALG-CHO) were mixed to prepare β-CD-g-PLGA/ALG hydrogel. The effect of solid content and molecular weight of β-CD-g-PLGA on the properties of hydrogel was studied. Simvastatin(SIM) was used as a model drug, the drug loading and release behavior of β-CD-g-PLGA/ALG hydrogel were researched. The introduction of β-CD into hydrogel made it an effective SIM loading and sustained release system.



Polyethylene-b-poly(ethylene/1-octene) Block Copolymer Prepared via Novel Dinuclear FI/Nickel(Ⅱ) α-Diiminecatalytic Systems

ZHANG Yixin, WANG Mengxue, ZHANG Zheyuan, MI Puke, WANG Tinglan

2017, 38(8):  1497-1502.  doi:10.7503/cjcu20160957

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A novel dinuclear phenoxyimine zirconium catalyst(CatB) was synthesized and constituted catalytic system with nickel(Ⅱ) α-diimine catalyst(CatA). The catalytic system was used for the preparation of polyethylene-b-poly(ethylene/1-octene) copolymer in the presence of co-catalyst(MAO) and chain shuttling agent diethylzinc(ZnEt₂). Polymer structure was characterized by differential scanning calorimetry(DSC), Fourier transform infrared spectrophotometer(FTIR) and carbon nuclear magnetic resonance(¹³C NMR). The results showed that under the same condition:toluene as solvent, pressure 1.0 MPa, temperature 50℃, n(MAO)/n(CatA+CatB)=300:1, c(1-octene)=0.58 mol/L, the insert amount of 1-octene on copolymer was 4.9%. The DSC curve presented bimodal profile and the "soft" segment of the products was more concentrated.