Journal of Chemistry
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2018
·
IF 1.726
Zou Bin,Chen Xueshan,Xia Jiaojiao,Zhou Cunshan
Conversion of HMF into FDCA was carried out by a simple and green process based on alkaline ionic liquid (IL) modified Pd/C catalyst (Pd/C-OH−). Alkaline ionic liquids were chosen to optimize Pd/C catalyst for special hydrophilicity and hydrophobicity, redox stability, and unique dissolving abilities for polar compounds. The Pd/C-OH− catalyst was successfully prepared and characterized by SEM, XRD, TG, FT-IR, and CO2-TPD technologies. Loading of alkaline ionic liquid on the surface of Pd/C was 2.54 mmol·g−1. The catalyst showed excellent catalytic activity in the HMF oxidation after optimization of reaction temperature, reaction time, catalyst amount, and solvent. Supported alkaline ionic liquid (IL) could be a substitute and promotion for homogeneous base (NaOH). Under optimal reaction conditions, high HMF conversion of 100% and FDCA yield of 82.39% were achieved over Pd/C-OH− catalyst in water at 373 K for 24 h.
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Royal Society Open Science
·
2018
·Vol. 5
·期 9
·
IF 2.504
Benyong Han,Wudi Zhang,Fang Yin,Shiqing Liu,Xingling Zhao,Jing Liu,Changmei Wang,Hong Yang
Methyl laurate was synthesized from lauric acid (LA) and methanol via an esterification reaction using ionic liquids (ILs) as catalysts. The efficiencies of three different catalysts, 1-methylimidazole hydrogen sulfate ([Hmim]HSO4), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4) and H2SO4, were compared. The effect of the methanol/LA molar ratio, reaction temperature, reaction time and catalyst dosage on the esterification rate of LA was investigated by single-factor experiments. Based on the single-factor experiments, the esterification of LA and methanol was optimized using response surface methodology. The results showed that the most effective catalyst was the IL [Hnmp]HSO4. The optimal conditions were as follows: [Hnmp]HSO4 dosage of 5.23%, methanol/LA molar ratio of 7.68 : 1, reaction time of 2.27 h and reaction temperature of 70°C. Under these conditions, the LA conversion of the esterification reached 98.58%. A kinetic study indicated that the esterification was a second-order reaction with an activation energy and a frequency factor of 68.45 kJ mol−1 and 1.9189 × 109 min−1, respectively. The catalytic activity of [Hnmp]HSO4 remained high after five cycles.
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CHEMISTRY-A EUROPEAN JOURNAL
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2018
·Vol. 24
·期 61
·16407-16417
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IF 5.16
Ting Chen,Yanqiao Xu,Lianjun Wang,Weihui Jiang,Wan Jiang,Zhixiang Xie
Graphical Water-soluble quantum dots (QDs) consisting of Cu-In-Zn-S (CIZS) have been prepared by microwave treatment with the assistance of room-temperature ionic liquid. During the process, the instantaneous nucleation rate can be improved, which results in the rapid synthesis of CIZS QDs at low temperature. The weakly coordinating BF 4 − is prone to produce F − , which can passivate the surface dangling bonds effectively and thereby improve the photoluminescence (PL) intensity significantly. A facile approach towards photoluminescent (PL) Cu-In-Zn-S quantum dots (CIZS QDs) has been developed, comprising microwave treatment with the assist of room-temperature ionic liquid (RTIL). Because of its high polarizability, RTIL served as a microwave absorbent, which resulted in the increase of the instantaneous nucleation rate and the rapid synthesis of CIZS QDs at low temperature. Moreover, the surface decoration of QDs with RTIL can passivate the surface defects greatly. The PL intensity of the CIZS QDs depends on the anion species, alkyl chain length of the RTIL, and the metal element ratios of the QDs. On the basis of the variable PL peak position and extended luminescence lifetime of the CIZS QDs, the superior emission behavior of the QDs was confirmed by surface etching with fluoride produced by the hydrolysis of RTIL 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF 4 ). Moreover, the intermediate alkyl chain length of the RTIL can avoid aggregation, which results in the construction of CIZS QDs with homogenous size distribution. The shape-controlled CIZS QDs show a broadened tunable emission peak from 677 to 579 nm compared with that of QDs prepared by a conventional one-pot method by mixing the raw materials. CIZS QDs also exhibit a high quantum yield (QY) of 24.1 % after coating with a ZnS shell. This method is expected to be a useful technique for the rapid synthesis of multiple QDs with a wider range of emission wavelengths and higher QY for a variety of applications.
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CHINESE JOURNAL OF CATALYSIS
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2018
·
IF 3.525
Xiying Fu,Pengtao Xie,Yiwei Lian,Leqin He,Wei Zhao,Tao Chang,Shenjun Qin
A series of zwitterionic-type quaternary ammoniums (ZTQAs) with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO 2 and various terminal epoxides. The prolonged alkyl chain of ZTQAs exhibited temperature-responsive self-separation in propylene carbonate (PC). The interaction between ZTQAs and KI was confirmed by X-ray photoelectron spectroscopy and quantum chemical calculations. This interaction strengthened the nucleophilicity of the I − ion, favoring the catalytic reaction . The 3-(dimethyltetradecylammonium) propane sulfonate (DTPS)/KI showed an excellent yield of PC (95.1%) at 125 °C, 1.5 MPa, and 1 mol% loading of catalyst. The precipitate formed spontaneously from the catalytic system, providing high catalytic activity of the homogeneous catalyst, as well as easy recovery of the heterogeneous catalyst.
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RSC Advances
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2019
·Vol. 9
·期 26
·14974-14981
·
IF 3.049
Zhongliang Zhao,Caihong Zhu,Qianping Guo,Yan Cai,Xuesong Zhu,Bin Li
Molecular imprinting of proteins has evolved into an efficient approach for protein recognition and separation. However, maintaining the structural stability of proteins during the preparation process of molecularly imprinted polymers (MIPs) remains challenging. Ionic liquids (ILs), being capable of maintaining the stability of proteins, might enable effective imprinting and accurate recognition of proteins. In this study, lysozyme (Lyz)-imprinted titanium dioxide (TiO2) nanoparticles, TiO2@Lyz-MIPs, have been successfully prepared for selective recognition and separation of Lyz. This was achieved by the free radical polymerization of hydroxyethyl acrylate (HEA) and poly(ethylene glycol) dimethacrylate (PEGDMA) on polydopamine (PDA)-modified TiO2 nanoparticles using an IL, choline dihydrogen phosphate (chol dhp), as the stabilizer of Lyz. It was found that both PDA modification of TiO2 and the use of chol dhp as stabilizer improved the adsorption capacity of TiO2@Lyz-MIPs toward Lyz. When the concentration of HEA was 7 mg mL−1, the ratio of monomer to crosslinker was 20 : 1, and the concentration of chol dhp was 12.5 mg mL−1, the highest imprinting factor of 4.40 was achieved. TiO2@Lyz-MIPs exhibited relatively high adsorption capacity with the maximum adsorption capacity up to 120 mg g−1, which was more than four times higher than that of the non-imprinted polymers (NIPs) counterpart, TiO2@Lyz-NIPs. The adsorption rate of Lyz by TiO2@Lyz-MIPs was also much higher than that of TiO2@Lyz-NIPs. TiO2@Lyz-MIPs could successfully separate Lyz from diluted egg white, a complex mixture of proteins. Findings from this study indicate that effective recognition cavities toward Lyz were formed on the surface of Lyz-imprinted TiO2 nanoparticles prepared using IL as the template stabilizer. This approach may facilitate the development of MIPs for efficient protein recognition and separation.
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RENEWABLE ENERGY
·
2018
·
IF 4.9
Yongqiang Wang,Dan Zhao,Guanyi Chen,Shejiang Liu,Na Ji,Hui Ding,Jianfeng Fu
For biodiesel production from waste cooking oils with high acid values, an inefficient esterification pretreatment is always conducted to convert free fatty acids (FFAs) before alkali-catalysed transesterification process. In this paper, phosphotungstic acid based poly(ionic liquid) was prepared to catalyse the esterification of palmitic acid with methanol while the required catalyst dosage was much lower than commercial Amberlyst-15. And the catalyst was characterized by 31 P CP-MAS NMR, FTIR, SEM, XRF and TG. Among the three poly(ionic liquid)s prepared in this paper, phosphotungstic acid based poly(ionic liquid) was selected to be the most suitable catalyst for esterification because the catalyst could be reused for more than 5 times without significant deactivation. According to single factor analyses, the esterification yield could reach 91.6% after 8 h while the reaction temperature, methanol to acid molar ratio and catalyst dosage were 65 °C, 6 and 3% wt, respectively. Afterwards, palmitic acid was proposed to be first adsorbed on the catalyst before reacting with methanol. Finally, a palmitic acid adsorbed Eley-Rideal model was employed to analyse the reaction and the adsorption mechanism was assumed as well.
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BIORESOURCE TECHNOLOGY
·
2018
·
IF 5.807
Xianfeng Hou,Zhinan Wang,Jin Sun,Meng Li,Shujie Wang,Kai Chen,Zhenzhong Gao
A novel pretreatment strategy based on combination of microwave and ionic liquid [TBA][OH] was developed for enhancing enzymatic hydrolysis of Eucalyptus sawdust. The sugar yield of pretreated sample achieved 410.67 mg/g in 48 h, which suffered from optimized microwave-assisted [TBA][OH] pretreatment. The work mechanism was illuminated by chemical composition, Fourier transform infrared spectroscopy (FTIR), 13 C cross polarization/magic-angle spinning solid state NMR ( 13 C solid NMR), X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The combined effect of microwave and [TBA][OH] leads to the violent deconstruction of lignin, removal of hemicelluloses, destruction of crystalline region and an eroded, pored and irregular micro-morphology. As a green, relatively inexpensive and high efficient pretreatment, microwave-assisted [TBA][OH] pretreatment has great potential in the field of bio-refinery.
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FOOD CONTROL
·
2019
·
IF 4.248
Na Li,Xiaoying Liu,Jihe Zhu,Bijing Zhou,Junxian Jing,Aibing Wang,Rui Xu,Zhou Wen,Xingbo Shi,Shiyin Guo
A simple and sensitive electrochemical biosensor for acrylamide (AA) detection based on hemoglobin (Hb) entrapped in ionic liquid-carbon paste was constructed. The Hb-carbon ionic liquid paste electrode (Hb/CILPE) was studied and characterized by scanning electron microscopy (SEM) and electrochemical method. The surface passivation of the Hb/CILPE could be achieved by the addition of acrylamide molecule, which caused the lower current response value owing to the adduct formed by acrylamide and Hb as a result of the reaction between the α-NH2 group and the N-terminal valine of Hb. The experimental conditions such as pH value of supporting electrolyte, pulse increment and concentrated time of AA was examined. Under the optimum conditions, the differential pulse voltammetry (DPV) responses of Hb/CILPE toward AA was evaluated in a good linear range from 1.0 × 10 −11 to 1.0 × 10 −5 M, with a detection limit of 5.0 × 10 −12 M at S/N = 3. This biosensor can be successfully applied to the determination of AA in a real sample without complex pretreatment. Compared with other electrochemical methods for detecting AA, the prepared electrochemical biosensor exhibited advantages of simple preparation, easy surface renewal, better reproducibility and satisfactory stability.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
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2019
·
IF 5.04
Liting Guo,Changdong Gu,Jie Feng,Yongbin Guo,Yuan Jin,Jiangping Tu
A hydrophobic epoxy resin coating with an environmental-friendly deep eutectic solvent (DES)-based conversion pretreatment was proposed to enhance the corrosion resistance of magnesium alloys . The hydrophobic epoxy resin coatings on the AZ31B magnesium alloy with and without the DES-based conversion pretreatment were thoroughly compared. It is found that the DES-based conversion film on the AZ31B magnesium alloy is mainly composed of MgH 2 , MgO and MgCO 3 . Furthermore, the conversion film possesses porous structure, which provides more anchor points for the following epoxy resin coating. However, without the DES-conversion pretreatment, the epoxy resin is difficult to be attached on the substrate during the dip-coating process. The double layered hybrid coating system promotes the corrosion resistance of the magnesium alloys significantly, which can be ascribed to the unique architecture and component including the hydrophobicity of the surface layer, the dense and interlocked epoxy resin, and the corrosion resistant DES-based conversion pretreatment.
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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 39
·15700-15705
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IF 3.069
Yan Lei,Limei Yu,Maochang Shen,Shikang Luo,Zhanxian Gao
A series of ionic liquids (ILs) were synthesized and their Hammett acidities (H0) were determined using 4-nitroaniline as the indicator. The relationship among IL's structure, the acid strength, and the catalytic performance in the condensation reaction of 9-fluorenone with phenol was discussed. The effective H0 range of ionic liquids that can catalyse the condensation reaction was obtained. Moreover, the catalysis of the mercapto compound co-catalyst was also systematically studied. According to the analysis of how the structure of the sulfydryl co-catalyst affects the percent conversion of 9-fluorenone and the selectivity of BHPF, a mechanism for the reaction in the IL–thiol cooperative catalytic system was proposed. The present work gave a clear clue to design novel IL catalysts for the synthesis of BHPF.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2019
·
IF 1.911
Yu Ji,Tengda Zhang,Xia Gui,HaiJian Shi,Zhi Yun
The ketalization of glycerol with acetone was conducted over an ionic liquid [P(C 4 H 9 ) 3 C 14 H 29 ][TsO] (TTPT) in a batch reactor. A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a maximum solketal yield of 86% is achieved at acetone/glycerol molar ratio of 6/1, reaction time of 0.5 h, reaction temperature of 303 K, catalyst amount of 5 wt% of glycerol. TTPT was recycled and reused for ten times without obvious losses in terms of quantity and activity. Furthermore, effects of various experimental parameters (stirring speed, catalyst loadings, temperature and reactant composition) on the reaction kinetics are investigated. In terms of kinetics modeling, K γ is fitted by reactant composition at the temperature range 298 K–323 K, which was a concise strategy that showed good precision in the kinetics fitting. The activation energy for this ketalization reaction was evaluated to be 28.2 kJ·mol −1 . In addition, the kinetics of the reaction at a temperature exceeding the boiling point of acetone were also studied. We believe that all the results are important for further development of a technology for the continuous synthesis of solketal.
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Polymers
·
2017
·Vol. 9
·期 10
·478
·
IF 3.364
Chongrui Zhang,Xiaoqian Mi,Junyu Tian,Junheng Zhang,Tiwen Xu
The present study aims to improve the mechanical properties of epoxy composite by incorporating supported ionic liquid silica (IL-silica). The IL-silica not only showed improved interfacial interaction and reinforcement, but also served as cure agent of epoxy composites. The differential scanning calorimetry analysis revealed that epoxy composites could be successfully cured with IL-silica without any routine curing agents. IL-silica/epoxy composites presented higher mechanical and thermal properties compared with epoxy composite containing un-functionalized silica (u-silica). The dynamic mechanical analysis showed that the storage modulus of composites significantly increased with the addition of IL-silica in comparison to that with added u-silica, as well as the variation ofTgparameter. The incorporation of IL-silica simultaneously enhanced the tensile strength, toughness, and thermal stability of the epoxy composites. The considerable improvements in mechanical and thermal properties are ascribed to the improved dispersion of IL-silica and the enhanced interfacial interactions between epoxy matrix and IL-silica by strong covalent bonding, which results in an effective load transfer.Keywords:epoxy resin;silica;composites;supported ionic liquid;curing agent
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