Chem. J. Chinese Universities

Cover and Content of Chemical Journal of Chinese Universities Vol.44 No.4(2023)

2023, 44(4): 1-6.

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Synthesis and Deep Desulfurization Activity of Fuel Oil of PW₁₁M@Cu₃（BTC）₂ Hybrid

HAN Xu, BAI Xue, ZHANG Zhong, YANG Yanli, CUI Hong, LIU Shuxia

2023, 44(4): 20220702. doi:10.7503/cjcu20220702

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Transition metal monosubstituted Keggin-type tungstophosphates（PW₁₁M， M=Ti⁴⁺， Cr³⁺， Mn²⁺， Fe³⁺， Co²⁺， Ni²⁺， Cu²⁺， Zn²⁺） were synthesized and supported in a Cu₃（BTC）₂ metal-organic framework， a series of transition metal-substituted polyoxometalate-based metal-organic framework hybrids［PW₁₁M@Cu₃（BTC）₂］ was obtained. The compositions， structures and porosity of the hybrids were determined by single crystal X-ray diffraction analysis， elemental analysis（ICP）， powder X-ray diffraction（PXRD）， thermogravimetric analysis（TG）， N₂ adsorption-desorption experiment， etc. The series of hybrid materials have good adsorption effect on dibenzothiophene in fuel oil， and rapidly catalyze its oxidation to dibenzothiophene sulfone， and realize deep desulfurization of fuel oil with oxygen as oxidant.

Synthesis of Biochar Derived from Jujun Grass and the Application in Supercapacitors

LIU Junhui, LI Zijia, WU Shuchang, XIE Zailai, CHEN Yiquan

2023, 44(4): 20220653. doi:10.7503/cjcu20220653

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The powder carbonaceous material（JPC） was obtained by pre-carbonizing Jujun grass at low temperature， and then activated with different proportions of KOH at different temperatures， amorphous carbon material（JPCK1） with microporous and mesoporous distribution was obtained. The specific surface area of the synthesized carbon JPCK1-900-4X is up to 3368 m²/g， with large pore volume and 0.95%（atomic percent） nitrogen content. Electrochemical tests showed that JPCK1-900-4X has good energy storage potential in supercapacitor applications. When the current density is 0.5 A/g， the specific capacitance is 311.7 F/g， and when the current density is increased to 10 A/g， the specific capacitance is 230 F/g. After 5000 cycles of charging and discharging at the current density of 10 A/g， the capacitance retention rate is 97.5%， which indicates that it has good stability. In the two-electrode system， when the power density is 250 W/kg， the energy density can reach 17.7 W·h/kg.

Novel Electrochemical Sensor Based on Molybdenum Disulfide and Cobalt Based Metal Organic Frameworks Nanocomposites for Trace Mercury Detection

WANG Ri, BIAN Chao, XIE Yong, HAN Mingjie, LI Yang, XIA Shanhong

2023, 44(4): 20220719. doi:10.7503/cjcu20220719

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The detection of trace mercury ions（Hg²⁺） in water is imperative to ensure water quality and human health. In this work， a novel electrochemical sensor based on molybdenum disulfide（MoS₂） and cobalt based metal organic frameworks nanocomposites（MoS₂@ZIF-67） was developed to detect trace Hg²⁺ in water through differential pulse voltammetry. MoS₂@ZIF-67 amplified the electrochemical signals and improved the electrochemical activity of the sensor， which combined the excellent conductivity of MoS₂ and catalytic performance of metal organic frameworks. The specific detection of Hg²⁺ was realized by the double strand structure of T-Hg²⁺-T formed by Hg²⁺ and thymine T in DNA. The sensor achieved excellent performances in detection of Hg²⁺， including a low limit of detection（5 ng/L）， considerable linear range（0.01—10 μg/L）， good selectivity and satisfactory recovery in tap water samples， which had the potential for application in the future.

Two New Holostane-type Glycosides from Apostichopus Japonicus Selenka

SUN Zhiheng, LIU Guiying, WANG Bingzi, CHEN Yifu, FENG Yuezhu, JIN Yongri, LI Xuwen

2023, 44(4): 20220678. doi:10.7503/cjcu20220678

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In this study， two new holostane-type glycosides were isolated from the ethanol extract of Apostichopus japonicus Selenka. Combined spectral data analysis with physical and chemical properties， they were identified as 3β-O-｛2-O-［3-O-methyl-β-D- glucopyranosyl-（1→3）-β-D-xylopyranosyl-（1→4）-β-D-quinovopyranosyl］-4-O-［β-D-glucopyranosyl］-β-D-xylopyranosyl｝-holosta-7（8），25（26）-dien-16-one（compound 1， named holotoxin E₁） and 3β-O-｛2-O-［3-O-methyl-β-D-glucopyranosyl-（1→3）- β-D-xylopyranosyl-（1→4）-β-D-glucopyranosyl］-4-O-［β-D-glucopyranosyl-（1→3）-β-D-glucopyranosyl］-β-D-xylopyranosyl｝-holosta-7（8），25（26）-dien-16-one（compound 2， named Holotoxin E₂）. Moreover， CCK-8 assay was used to determine the inhibitory activities of these two new compounds together with four known holostane-type glycosides against MDA-MB-231 cells and HepG2 cells. The results showed that the compounds except Holotoxin E₂had good inhibitory activities against MDA-MB-231（IC₅₀= 2.386—4.686 μmol/L） and HepG2（IC₅₀=5.909—18.860 μmol/L）.

In situ Magnetic Resonance Imaging of Solvent Infiltration on γ -Al₂O₃ Particles

XU Ruotao, WANG Qiang, BAO Qingjia, WANG Weiyu, ZHANG Zhi, LIU Zhaoyang, XU Jun, DENG Feng

2023, 44(4): 20220587. doi:10.7503/cjcu20220587

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Impregnation method is commonly used to prepare high-performance catalyst via loading metal or active phase on porous solid support. Solvent infiltration on the support during the impregnation process is essential for the distribution and state of the supported active components， which impact the catalytic property of the supported catalyst. In this study， magnetic resonance imaging（MRI） is implemented for in situ investigation of the solvent infiltration process on γ-Al₂O₃ particles. MRI of γ-Al₂O₃ particles infiltrated with sufficient water was evaluated by three different MRI sequences， i. e. ， spin-echo（SE）， gradient-echo（GRE） and ultra-short time of echo（UTE）. It is found that the UTE sequence is superior in the acquisition of ¹H MRI signals with short T₂ values. The selection of very short time of echo（TE） values can significantly alleviate the differences in signal intensity caused by protons with different mobility. Particularly， the signals from the motion-restricted protons that diffuse into interior of γ-Al₂O₃ particles can be observed by using the UTE sequence. Meanwhile， the use of small excitation angle and short time of recovery（TR） in UTE allows to obtain the dynamic images with higher time resolution（<1 min） than that of SE and GRE sequences. The UTE sequence is employed to in situ monitor the infiltration process of γ-Al₂O₃ particles in solvent with distinct polarities. For polar solvent water and methanol， both show a typical free diffusion process that the solvent gradually diffuses from the outer edge of the particle to its center up to saturation. Interestingly， there is a different infiltration behavior for the non-polar solvent cyclohexane， and the overall ¹H MRI exhibits strong central signal and low edge signal in the γ-Al₂O₃ particles after immersed for a certain time. The "liquid film" with a strong signal intensity is formed around the particle， which probably prevents the infiltration of outer cyclohexane into particles， thus affecting the subsequent molecular diffusion and redistribution in the particles.

Differentiation and Investigation of Ginsenoside Isomers 20（S）-Rf and Rg₁ by Energy-resolved Mass Spectrometry

ZHAO Huanxi, LI Zhuo, ZHAO Mengya, TIAN Lu, XIAO Yusheng, WANG Zhenhuan, YUE Hao, XIU Yang

2023, 44(4): 20220576. doi:10.7503/cjcu20220576

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An energy-resolved mass spectrometry（ERMS） method was developed for the differentiation and investigation of ginsenoside isomers 20（S）-Rf and Rg₁ by combining continuously varied collision energy with tandem mass spectrometry. The ratio of product ion intensity to its precursor ion intensity was defined as intensity fraction（IF）， whereas the ratio of two product ion intensities was defined as intensity ratio（IR）. IF and IR were plotted against the continuously varied collision energy to establish the IF and IR curves， respectively. Although the tandem mass spectra of ginsenoside isomers 20（S）-Rf and Rg₁ were almost identical， multivariate statistical analysis showed significant differences in the IF and IR profiles of their characteristic fragment ions ［M-Glc-H］^‒，［M-2Glc-H］^‒， and ［M-2Glc-C₆H₁₂-H］^‒ with distinct differentiation boundaries that could directly distinguish 20（S）-Rf and Rg₁. The relative molar contents of 20（S）-Rf and Rg₁ in the biotransformation products of protopanaxtriol-type ginsenosides were further analyzed in real time using ERMS. All the results showed that ERMS enables the rapid differentiation and relative content monitoring of 20（S）-Rf and Rg₁ without the separation by liquid chromatography.

Structural Characterization of a Homogeneous Polysaccharide Isolated from the Flower of Carthamus Tinctorius L. and Its Inhibitory Activity on HepG2 Proliferation

XU Yongbin, FENG Shuaixia, CHEN Jie, GONG Huan, SHI Songshan, WANG Huijun, WANG Shunchun

2023, 44(4): 20220600. doi:10.7503/cjcu20220600

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To isolate， purify and characterize the structure of polysaccharide from flowers of Carthamus tinctorius L.， and to investigate the inhibitory effect of its homogeneous polysaccharide on the proliferation of HepG2 hepatoma cells. The polysaccharides in flowers of Carthamus tinctoriusL. were extracted by water extraction and alcohol precipitation. The crude polysaccharides were separated and purified by anion exchange column and molecular sieve gel column. The homogeneity and molecular weight distribution were determined by high performance gel permeation chromatography（HPGPC）. Its structure was elucidated by monosaccharide composition， methylation， and nuclear magnetic resonance（NMR） methods. The inhibitory effect of flowers of Carthamus tinctoriusL. polysaccharide on tumor cells was studied by in vitro cell experiments. A homogeneous polysaccharide（CTPS-1A） was obtained. The molecular weight of CTPS-1A was 53800. The monosaccharide composition of CTPS-1A was analyzed by gas chromatography-mass spectrometer（GC-MS） and the monosaccharide composition was n（arabinose）∶n（galactose）=59.2∶40.8. By methylation analysis， the glycosidic linkages were T-Galp， 1，3-Galp， 1，6-Galp， 1，3，6-Galp， T-Araf， 1，5-Araf， and 1，3，5-Araf. The results showed that CTPS-1A was an arabinogalactan（AG）， its main chain was composed of -β-Galp-（6→1）-β-Galp-（6→， and T-β-Galp， 1，3-β-Galp， T-α-Araf， 1，5-α-Araf， 1，3，5-α-Araf were connected to the 3 position of 1，3，6-Galp. The results of in vitro culture of HepG2 cells showed that CTPS-1A inhibited the growth of HepG2 by enhancing nuclear contraction and apoptosis.

Effect of Intermolecular Interaction on the Properties of Benzophenone-based AIDF Materials

WANG Yingjie, PAN Zehui, TAO Zhengyu, WANG Yan, TONG Bihai, FUNG Mankeung, SONG Mingxing

2023, 44(4): 20220562. doi:10.7503/cjcu20220562

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Four benzophenone luminescent materials with phenoxazine as donor were synthesized. The effects of different aromatic substituents on the intermolecular interaction and photoelectric properties of the materials were investigated. The coplanar modification of polycyclic aromatic hydrocarbons will result in a large number of strong π⁃π stacking interactions between molecules， while the three-dimensional triptycene group can avoid these interactions. The four compounds had very high thermal stability. Their temperature corresponding to 5% mass loss to the initia mass（T_d，5） was above 400 ℃， the π⁃π stacking between molecules will obviously improve the thermal stability of the materials. Except for the perylene modified compounds， the other three compounds had obvious aggregation- induced delayed fluorescence（AIDF）， their calculated energy gap（ΔE_st） values were not exceed 0.01 eV. Their photoluminescence efficiency in PMMA thin films was high. The photoluminescence efficiency in PMMA thin films was between 0.60 and 0.78， and increased first and then decreased with the decrease of intermole-cular force. The electroluminescent performance test showed that the compound modified by triptycene had the best electroluminescent performance. The maximum brightness of the doped device was up to 48480 cd/m²， and the peak power efficiency（PE_max） and peak external quantum efficiency（EQE_max） were 54.4 lm/W and 19.0%， respectively. The PE_max and EQE_max of the undoped device were still as high as 33.5 lm/W and 13.4%， indicating that the concentration quenching phenomenon was well suppressed and it has the potential to be applied to organic electroluminescence.

Fluorescence Sensing of Fe³⁺， Cu²⁺ by Coumarin Functionalized Pillar［5］arene

SU Lijiao, BAO Qiulian, YANG Yunhan, LUO Jianping, YANG Ju, ZHANG Juntong, TAO Xin, CHUAN Yongming, YANG Lijuan

2023, 44(4): 20220549. doi:10.7503/cjcu20220549

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A fluorescence probe of coumarin functionalized pillar［5］arenes（P5X） with aggregation induced emission（AIE） effect was synthesized. P5X showed strong AIE performance in DMSO/H₂O（volume ratio： 4∶1） solution. When Fe³⁺ or Cu²⁺ were added to P5X solution， the blue fluorescence of the system was quenched. The lowest detection limits of P5X for Fe³⁺ and Cu²⁺ were 5.21×10^-6 mol/L and 2.48×10^-6 mol/L， respectively. In addition， the probe also had the advantage of strong anti-interference ability， and could realize efficient and sensitive detection of Fe³⁺ and Cu²⁺. The new method for the detection of Fe³⁺ and Cu²⁺ can provide a reference for the detection of related ions in environmental or biological fields.

Mechanism of Tau R2/Wt Morphology Affected by Osmolytes Using Molecular Dynamics Simulations

SU Lili, SHAO Xueguang, CAI Wensheng

2023, 44(4): 20220745. doi:10.7503/cjcu20220745

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Molecular dynamics simulation was used to study the effects of urea and Trimetlylamine oxide（TMAO） on the folding and conformation of the second repeat of the intrinsically disordered protein Tau（R2/wt） in the presence of urea and TMAO as osmolytes. The distribution of hydrogen bonds， the mobility of water molecules， and the water structure around the fragment were analyzed and compared with the results in pure water. The results show that the R2/wt fragment without osmolyte can form a stable end-to-end hairpin conformation for a long time， the number of intramolecular hydrogen bonds in the peptide chain is higher， and the water molecules around the R2/wt fragment are more mobile. When urea is used as an osmolyte， the intramolecular salt bridges of R2/wt are difficult to form， leading to a fully unfolded conformation； the hydrogen bonding between water molecules around the peptide chain and between water molecules and the peptide chain is weakened， resulting in an decreased mobility of water molecules around the R2/wt chain， and a decreased proportion of highly structured water molecules. When TMAO is used as an osmolyte， the R2/wt fragment can only form an unstable hairpin structure， which is easy to transition to an expanded state. The distribution of hydrogen bonds and water structure around the peptide chain does not change significantly compared with that in the absence of osmolytes， but the mobility of water molecules around the peptide chain also decreases. In conclusion， the addition of osmolytes can change the morphological distribution pattern of R2/wt fragment， and further change the hydrogen bonding， water structure and mobility around the peptide chain. The results provide guidance for regulating the aggregation behavior of R2/wt fragments.

Effects of Amino Content of Aminated Carbon Nanotubes on Specific Capacity of Cathode for Li-sulfur Battery

XUE Zhuan, MU Zhonglin, HE Runhe, LI Yongbing, ZHANG Xingxiang

2023, 44(4): 20220709. doi:10.7503/cjcu20220709

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In order to improve the electrochemical performance of lithium sulfur batteries， aminated carbon nanotubes（MWCNT-NH₂） were used to improve the properties of cathode. MWCNT-NH₂was fabricated by Diels- Alder（D-A） reaction. A series of specimen were obtained by changing the reaction time. The samples were analyzed and characterized using thermogravimetric analyzer， Raman spectrometer and infrared spectrometer. The results show that， the amino content of MWCNT-NH₂ rises with the increase of D-A reaction period， and the grafting rate reaches 10.02 mmol/g at 16 h. The electrochemical performance of four cells assembled from MWCNT-NH₂ composites with different amino content was analyzed. The results show that， the higher the amino content， the better the electrochemical performance. The initial discharge specific capacities of the cathode material with the highest amino content（SPAN/MWCNTs-NH₂-16） at 0.2C and 1.0C are 943.3 and 887.1 mA·h/g_composite. After 200 cycles at 0.2C， the reversible specific capacity is 716.4 mA·h/g_composite， and the capacity retention rate can be increased to 94.3%. The initial discharge specific capacities of SPAN/MWCNTs-NH₂-16 at high current density 4.0C are 475.7 mA·h/g_composite， It has excellent cycle performance and rate performance， and demonstrating its great potential for future application of energy storage.

Preparation and Characterization of an Inner Flower Gel Microsphere Double-embedded with the Activated-lipase

ZHANG Fan, ZHENG Lanlan, CAO Hong, CHENG Lufeng, LI Chun

2023, 44(4): 20220699. doi:10.7503/cjcu20220699

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Lipase was first activated to an open conformation（PEG-Lip） by polyethylene glycol（PEG8000）， then cocrystallized with Ca₃（PO₄）₂ into Ca₃（PO₄）₂@PEG-Lip crystal flowers， and then coated with calcium alginate gel to form a inner flower gel microsphere double-embedded activated-lipase［CA-Gel@Ca₃（PO₄）₂@PEG-Lip］. The gel microspheres were white and oval-shaped with a diameter of about 2 mm. Characterized by scanning electron microscopy（SEM）， energy dispersive spectrometer（EDS）， confocal microscopy（CLSM） and fourier transform infrared spectrophotometer（FTIR）， the activated lipase was embedded in Ca₃（PO₄）₂ crystals， and the Ca₃（PO₄）₂@PEG-Lip crystal flowers were entrapped in mesh pores of calcium alginate gel. Enzymatic properties showed that the heat resistance and the pH stability of CA-Gel@Ca₃（PO₄）₂@PEG-Lip were enhanced under the protection of double armors compared to free lipase. In the repeated utilization experiment， the rapid recovery of CA-Gel@Ca₃（PO₄）₂@PEG-Lip could be achieved with an aperture diameter of approximately 0.5 mm filter， and after 10 cycles， the enzyme activity was retained up to 83%， showing the obvious improvement of operational stability and reusability of the lipase. This paper provides a new idea and method for the development and utilization of lipase in food industry.

Catalytic Performance and Reaction Mechanism of Chlorobenzene Oxidation over MnO _x -CeO₂ Catalyst

GAO Fengyu, CHEN Du, LUO Ning, YAO Xiaolong, DUAN Erhong, YI Honghong, ZHAO Shunzheng, TANG Xiaolong

2023, 44(4): 20220690. doi:10.7503/cjcu20220690

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The influence factors（Mn/Ce molar ratio， reaction temperature， oxygen， water）， physicochemical properties， interaction process and reaction mechanism are analyzed and proposed on MnO _x -CeO₂ catalysts for chlorobenzene oxidation performances（activity， selectivity and stability）. With 5%（volume fraction） H₂O_gas and 5%（volume fraction） O₂， the optimum Mn₂Ce₁O _x catalyst obtains the chlorobenzene conversion rate of 80.6%， 86.8% and 97.5% at 100， 200 and 300 ℃， respectively. High reaction temperature， high oxygen content and also the presence of water are beneficial to the improvement of catalytic conversion and reaction stability. The doping procedure of MnO _x and CeO₂ multi-oxides increases specific surface area to 128.61 m²/g， decreases pore size to 6.17 nm， and strengthens surface acidity（especially at middle & strong acid sites） and also redox performance. The electron interaction（Ce⁴⁺/Ce³⁺ $↔$ Mn⁴⁺/Mn³⁺/Mn²⁺） and oxygen cycle（surface adsorbed oxygen $↔$ lattice oxygen） are the essential driving processes to promote the catalytic oxidation. Chlorobenzene molecules are adsorbed on the surface of Mn₂Ce₁O _x catalyst to de-chlorinate and form phenol， in turn， the ring-opening of aromatic ring is occurred and then oxidated into the formation of most critical acetate intermediates that result in as finial as possible CO₂， HCl or Cl₂， H₂O. Under the activation actions of water and oxygen molecules to hydroxyl groups and active-oxygen species， the adsorption-activation of chlorobenzene and deep oxidation of intermediates are enhanced and more beneficial to reduce the generation of by-products（chloroethoxyl， phenol and aldehydes， etc.） and also Cl-containing species， thus improving the catalytic activity and reaction stability.

Preparation and Electrochemical Properties of Al³⁺-Doped δ -MnO₂

XIA Ao, ZENG Xiaoxiong, LI Jiameng, CHEN Jun, TAN Guoqiang

2023, 44(4): 20220658. doi:10.7503/cjcu20220658

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Al³⁺-doped δ-MnO₂ nano-powders with different doping ratios were synthesized by hydrothermal method. The influence of Al³⁺-doping on the δ-MnO₂ crystal structure and electrochemical performance was characterized by X-ray diffraction， scanning electron microscopy， transmission electron microscopy， X-ray photoelectron spectro- scopy， cyclic voltammetry， electrochemical impedance spectroscopy and galvanostatic charge-discharge. The results suggested that Al³⁺ ions entered into the crystal lattice of δ-MnO₂ to replace some Mn³⁺ and Mn⁴⁺ ions， which enhanced the electrical conductivity and structural stability of δ-MnO₂， and thus significantly improved the electrochemical performance. When the molar ratio of Al³⁺/Mn²⁺ in the precursor was 0.45， the synthesized product （A0.45M） showed the best electrochemical performance. A0.45M delivered a specific capacitance of 207.61 F/g at a current density of 1 A/g， which was 2.4 times the capacitance of the pure δ-MnO₂（A0M）. Moreover， A0.45M could maintain a high specific capacitance of 100.81 F/g even after 10000 cycles at 10 A/g， with capacity retention ratio of 81.33%.

Preparation and Catalytic Performance of Surface-covered AuNPs@PNIPAM Composite Particles

YAN Yutian, WU Si, CHANG Kangkang, XIA Yuzheng, CHEN Xiaonong, SHI Shuxian

2023, 44(4): 20220636. doi:10.7503/cjcu20220636

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Gold nanoparticles（AuNPs） with high surface energy are easy to agglomerate in water， which restricts their applications. In this study， poly（N-isopropyl acrylamide）（PNIPAM） microgel and AuNPs were combined by electrostatic interaction through physical blending method inorder to cause negative citrate-stabilized AuNPs absorbed on the surface of positive PNIPAM microgels. The prepared surface-covered AuNPs@PNIPAM particles not only have excellent dispersion stability， but also exhibit a temperature-dependent colorimetric property， showing a reversible change of “red→purple→red” during the temperature change of 25 ℃→50 ℃→25 ℃. In addition， the p-nitrophenol（4-NP） reduction reaction was used as the simulated catalytic reaction to examine the catalytic performance of AuNPs@PNIPAM. The results showed that the catalytic performance of AuNPs@PNIPAM first decreased and then increased with temperature. Compared to similar materials reported in the literature， the AuNPs@PNIPAM showed both temperature-colorimetric properties and catalytic performance.

Combustion Mechanism Construction Based on Minimized Reaction Network： Combustion of Aromatic Hydrocarbon

XIA Wenwen, YU Hongjing, WANG Shiye, YAO Li, LI Xiangyuan

2023, 44(4): 20220616. doi:10.7503/cjcu20220616

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Based on the minimized reaction network（MRN） method， the combustion reaction mechanisms of benzene， toluene， ethylbenzene and n-propylbenzene for the specified chemical resolution， which consider both the necessary chemical species in combustion and the feasibility of three-dimensional combustion dynamic simulations， have been developed in this work. The chemical resolution is simply defined as the number of species involved in the reaction mechanisms. The new features of MRN approach including the small size of the reaction mechanisms， two-parameter rate constants， and the reversibility for all the“elementary”steps. The reaction mechanisms consist of 22 species with 35 reactions， 27 species with 42 reactions， 32 species with 58 reactions and 36 species with 68 reactions， for benzene， toluene， ethylbenzene and n-propylbenzene， respectively. It is worth noting that on the basis of the C3 core mechanism， the combustion mechanism of benzene has been constructed by adding 5 species and 14 reactions， and that of toluene constructed by adding 7 species and 15 reactions. On the basis of benzene mechanism， the combustion mechanism of ethylbenzene has been constructed by adding 4 species and 8 reactions， that of n-propylbenzene constructed by adding 3 species and 7 reactions， respectively. The correctness and reliability of these combustion reaction mechanisms have been verified by comparing with the experimental results of ignition delay time and laminar flame velocity.

Modification of Activated Carbon Electrode for Efficient Electrosorption of Co²⁺， Mn²⁺ and Ni²⁺

CHEN Jiaqi, CHENG Wanting, WEN Qiuhui, HAN Jingru, MA Fuqiu, YAN Yongde, XUE Yun

2023, 44(4): 20220598. doi:10.7503/cjcu20220598

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Two different modified activated carbon（AC） electrode materials were prepared by modification with H₃PO₄ and NaOH using commercial AC as raw material. The surface properties and electrochemical properties of the AC before and after modification were investigated using scanning electron microscope（SEM）， transmission electron microscope（TEM）， Brunauer⁃Emmett⁃Teller（BET） test， Fourier transform infrared spectroscopy（FTIR）， X-ray photoelectron spectroscopy（XPS） and electrochemical analysis. The results showed that the H₃PO₄ modification made the pore distribution of AC denser， and the NaOH modification made the pore structure on the surface of AC more clearer and uniform. The specific surface area of the original AC was increased after modification with H₃PO₄ and NaOH. Moreover， the content of oxygen-containing functional groups of AC was significantly increased by H₃PO₄ and NaOH modifications. The cyclic voltammetry results showed that both modification treatments improved the specific capacitance of the AC electrode. When the scanning rate was 5 mV/s， the specific capacitances of unmodified， H₃PO₄ and NaOH modified AC electrodes were 36.51， 77.25 and 85.19 F/g， respectively. The experimental results of electrosorption experiments demonstrate that both modified AC electrodes had excellent removal effects on Co²⁺， Mn²⁺ and Ni²⁺， and the electrosorption processes were more consistent with the Langmuir model. Under the same experimental conditions， the NaOH-modified electrode had higher removal rates and adsorption capacities for Co²⁺， Mn²⁺ and Ni²⁺. The removal rates could reach 96.84%， 94.37% and 96.90% ， respectively， and the adsorption capacities were 140.8， 111.4 and 108.5 mg/g， respectively. This work indicates the potential application of modified AC electrodes and electrosorption in the efficient remediation of Co²⁺， Mn²⁺ and Ni²⁺.

Application of Bisoxazoline-grafted Amino Acid Polymer as Chiral Catalytic Center in Asymmetric Henry Reaction

ZHU Jipeng, LIU Runhui, SONG Gonghua

2023, 44(4): 20220569. doi:10.7503/cjcu20220569

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A series of amino acid polymers with different solubility was prepared through controlling the ratio of L-Glutamic acid-1-ethyl ester to DL-cysteine and the ratio of initiator to monomer in the polymerization process. With the amino acicl polymer as carriers for chiral ligands， a series of bisoxazoline-grafted amino acid polymers was synthesized by the addition reaction between the double bond on the bisoxazoline ligand and the sulfhydryl group on the polymer. The polymers can be used as a recoverable chiral ligand to catalyze asymmetric Henry reaction. The enantiomeric excess（e. e.） value of the reaction is between 50%—90% and the yield is between 67%—95%. The catalyst can be recycled for at least 7 times without reactivation.

Carboxyl Functionalized Microfiltration Membrane PSF-g-PMAA： Preparation， Rejection and Removal Properties for Triazine Herbicides

DU Ruikui, GAO Baojiao, MEN Jiying

2023, 44(4): 20220695. doi:10.7503/cjcu20220695

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A redox surface-initiating system of —NH₂/S₂O $82$ ^- was constituted at the interface of amine-based chloromethylated polysulfone（CMPSF） microfiltration membrane by using persulfate. MAA was graft-polymerized on the surface of microfiltration membrane by using the surface-initiating graft-polymerization method， and the grafted microfiltration membrane of PSF-g-PMAA was obtained. The rejection and removing performance of PSF-g-PMAA membrane for the three triazine herbicides（ametryn， prometryn and atrazine） from water was examined by using isothermal adsorption experiments and the permeation experiments. The experimental results show that PSF-g-PMAA membrane has strong removal properties for the three triazine herbicides under the synergy adsorption of electrostatic interaction and hydrogen bond interaction， and the maximum adsorption capacity of PSF-g-PMAA membrane for ametryn can reach up to 0.18 μmol/cm²（41 μg/cm²）. Using an injection filter with a membrane area of 1.77 cm²， the rejection rate of PSF-g-PMAA membrane for the solutions of the three triazine herbicides with a concentration of 0.8 mg/L can be closed to 100% under 100 mL of penetrating liquids.

Impact Resistance Mechanism of Ultra-high Molecular Weight Polyethylene Molded Sheet

SONG Xinyue, WEI Yue, SHEN Jie, SHI Dean, YANG Huawei, LUAN Shifang

2023, 44(4): 20220641. doi:10.7503/cjcu20220641

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Ultra-high molecular weight polyethylene（UHMWPE） is an high performance engineering plastic with superior impact resistance， and the studies about its synthesis， processing and application have been a hot topic in modern polymer science， however， the mechanism behind its superior impact resistance is still unclear. In this work， four UHMWPE samples with viscosity average molecular weight around 5×10⁶ and impact strength from 54.7 to 152 kJ/m²were studied in order to reveal the impact resistance mechanism of UHMWPE. It is found that under the same compression molding conditions， the four UHMWPE samples have the same crystal form， similar crystallinity and lamellar thickness. During the impact strength test， the UHMWPE sheets show a characteristic repetitive “extension-fracture” anti-impact behavior， and the number and width of extended bands are positively correlated with the impact strength. It is also discovered that the entanglement density of the amorphous phase is negatively and linearly correlated with the impact strength with a goodness-of-fit as high as 0.9. Thus it can be concluded that controlling the entanglement of UHMWPE during its synthesis and processing procedure is really crucial to the impact strength.

Fabrication and Properties of Rosin-based Epoxy Vitrimer with Dual Dynamic Covalent Bonds

ZENG Yanning, YANG Bin, YUAN Rongyan, LUO Zhaoyi

2023, 44(4): 20220621. doi:10.7503/cjcu20220621

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Herein， rosin-based epoxy vitrimers（RE） with dual-dynamic covalent bonds （disulfide bond and ester bond） were fabricated by epoxy-carboxylic acid reaction with rosin derivative as an epoxy monomer， 3，3'-dithiodipropionic acid（DTDPA） as crosslinker. The structures of the RE networks were characterized by Fourier transform infrared spectroscopy（FTIR） and Raman spectroscopy， and the results indicated that rosin-based epoxy networks with dynamic disulfide bond and ester bond were successfully synthesized. Meanwhile， the thermo-mechanical properties， mechanical properties， thermal stability， and stress relaxation of the RE were investigated by dynamic mechanical analysis（DMA）， tensile testing， and thermogravimetric（TG） analysis. Furthermore， the effects of DTDPA content on self-healing and reprocessing capabilities of the RE networks were researched. The results show that the Rosin-based epoxy vitrimer which was prepared at a molar ratio of carboxyl in DTDPA/epoxy groups in rosin monomer=100∶100（RE-100） possess the excellent self-healing and reprocessing capabilities due to the most dynamic disulfide bonds and ester bonds in the network.

Influence of Surface Wettability and Surface Charge on Microbial Adhesion of Electrospun Polyaniline Coatings

BA Didi, ZHAO Haizhou, ZHANG Zhiming, YU Liangmin

2023, 44(4): 20220615. doi:10.7503/cjcu20220615

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The surface wettability and surface charge of the materials have a very important influence on the attachment of microorganisms to the material surfaces. In this paper， two kinds of polyaniline fiber coatings， hydrophobic and hydrophilic， were prepared on the surface of stainless steel electrodes by electrospinning. Electrochemical impedance spectroscopy was used to monitor the adhesion of Escherichia coli（E. coli） on the surfaces of the two polyaniline fiber coatings， and the results showed that the hydrophilic surface was beneficial to inhibit the adhesion of E. coli. Further， the hydrophilic surface was positively and negatively charged， respectively， by electrochemical polarization， and the bacteriostatic rate of two kinds of charge surface under different polarization times were studied by plate count method， and it was found that both positive and negative charges were beneficial to inhibit the attachment of microorganisms， and there was no significant difference between them. Moreover， under the same cathodic polarization conditions， the antibacterial properties of hydrophilic and hydrophobic polyaniline fiber coatings were not much different， indicating that the effect of electrochemical polarization on the inhibition of bacterial adhesion by electrospun polyaniline coatings is greater than that of surface wettability.

Microwave-assisted Biomineralization of Graphene to Enhance the Interfacial Interactions with Poly（lactic acid）

TANG Mengke, JIANG Liang, XU Wenxuan, ZHANG Zilin, TANG Daoyuan, HUANG Donghui, YANG Haoran, GAO Jiefeng, JI Xiang, WANG Yanqing, XU Huan

2023, 44(4): 20220601. doi:10.7503/cjcu20220601

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Graphene nanosheets have shown great application promise in promoting the mechanical performance and gas barrier properties for poly（lactic acid）（PLA）， which was dwarfed by the relatively poor interfacial interactions. Using the microwave-assisted aqueous biomineralization approach， this work disclosed a high-efficiency and ecofriendly route to direct decoration of graphene nanosheets with well-crystallized and high-uniformity hydroxyapatite nanowhiskers， yielding the biomineralized graphene（BMGr） nanohybrids with favorable dispersibility and strong interfacial adhesion. The BMGr nanohybrids were homogeneously exfoliated and adhered onto the PLA microfibers， followed by the confined processing at 60 ℃ and 3 MPa for fabrication of strong and tough PLA composite films with extensive interfacial interactions. It is worth noting that the tensile strength， Young’s modulus and tensile toughness of BMGr-reinforced PLA achieved 22.6 MPa， 199 MPa and 6.6 MJ/m³， which were 6.46， 3.75 and 8.25 times of those of pure PLA， respectively. This work is of important significance for effective decoration and surface modification of 2D nanosheets， as well as industrially viable fabrication of mechanically robust biodegradable nanocomposites.

Preparation and Characterization of a High Perm-selectivity Poly（amide/ester） Nanofiltration Membrane Using a Poly（vinylidene fluoride） Substrate

YANG Yanfu, WANG Qiqi, ZHANG Hui, ZHANG Qinglei, ZHAO Junqiang, ZHAO Yiping, CHEN Li

2023, 44(4): 20220574. doi:10.7503/cjcu20220574

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Using polyvinylidene fluoride（PVDF） as a substrate material， an amphiphilic triblock copolymer PHEAA-b-PMMA-b-PHEAA（PHMH） with hydrophilic poly（N-hydroxyethyl acrylamide）（PHEAA） and hydrophobic polymethyl methacrylate（PMMA） chain segments was used as a modifier for fabrication of PVDF/PHMH substrate via non-solvent induced phase separation method. The surface pore size of the PVDF/PHMH substrate was smaller than that of the unmodified PVDF substrate， and the porosity and hydrophilicity were increased. Compared with PVDF substrate nanofiltration membrane（N0）， PVDF/PHMH substrate nanofiltration membrane（N1） prepared via interfacial polymerization exhibited a higher surface roughness， hydrophilicity and lower molecular weight cut-off. The N1 membrane showed a rejection of Na₂SO₄ up to 96.0% and the water permeation flux was 304 L·m^-2·h^-1·MPa^-1， which exceeded those of commercial nanofiltration membranes.

Statistical Properties of Ring-based Polymers Formed in Polycondensation Systems

LI Jiangtao, ZHAO Xinxin, GU Fang, WANG Haijun

2023, 44(4): 20220561. doi:10.7503/cjcu20220561

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We present statistical properties of ring-based polymers formed in the polycondensation system consisting of ring polymers of $R B f$ type and monomers of $A B g$ type. The number- and weight-average molecular weights as well as polydispersity index of ring-based polymers are explicitly given. Furthermore， the effect of the molar ratio of reactants， the functionality and degree of polymerization of ring polymers on the average properties of ring-based linear and branched polymers are carried out. Consequently， a critical conversion is proposed， at which an inversion in the contribution of ring polymers to average properties of ring-based polymers takes place. Meanwhile， the polydispersity index of ring-based polymers decreases with functionality but does not depend on the molar ratio of reactants， while the critical conversion is closely related to all the above-mentioned factors. It is expected that the present results would be useful to elucidate the average properties of ring-based polymers prepared in the system under consideration.

Construction and Properties of DNA Hybrid Hydrogels

ZHANG Qi, SUN Rui, ZHANG Yu, LI Xia, ZHU Ying

2023, 44(4): 20220761. doi:10.7503/cjcu20220761

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DNA hybrid hydrogels based on pure DNA hydrogels were prepared by selecting three different hybrid factors to encode and restructure pure DNA hydrogels successively. The microstructure， mechanical properties and biological toxicity of DNA hybrid hydrogels were characterized. The results showed that the bivariate coding factor （sodium alginate/agarose） DNA hybrid hydrogels could meet the double evaluation indexes of mechanical strength and biological safety effect， with excellent biological safety， and improved mechanical properties by three orders of magnitude. The result of this work provides a new idea for programming DNA hydrogels， which expands its application in biomedical field.

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