JOURNAL OF CHEMICAL THERMODYNAMICS
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2015
·
IF 2.679
Jiayi Chen,Lingxiao Chen,Yingjie Xu
Densities and viscosities of the pure ionic liquid 1,1,3,3-tetramethylguanidine imidazole ([TMG]IM) and its binary mixtures with methanol, ethanol, 1-propanol, and 1-butanol were measured at temperatures from T = (293.15 to 313.15) K. The thermal expansion coefficient, molecular volume, standard entropy, and lattice energy of [TMG]IM were obtained from the experimental density value. The temperature dependence of the viscosity of [TMG]IM was fitted to the fluidity equation. Excess molar volumes V E and viscosity deviations Δ η of the binary mixtures were calculated and fitted to the Redlich–Kister equation with satisfactory results. The result shows that the V E values of the binary mixtures are negative over the whole composition range, while Δ η values have an S-shape deviation. Temperature has little effect on the V E of the systems, but it has significant effect on the Δ η . Furthermore, the absolute values of V E for {[TMG]IM (1) + alcohol (2)} systems at the same temperature decrease with increasing carbon alkyl chain of the primary alcohol. Other derived properties, such as the apparent molar volumes, partial molar volumes, excess partial molar volumes, Gibbs free energy of activation for viscous flow, and excess Gibbs free energy of activation for viscous flow of the above-mentioned systems were also calculated.
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ACS Applied Materials & Interfaces
·
2015
·
IF 6.723
Qiao An,Zifeng Li,Robert Graff,Jia Guo,Haifeng Gao,Changchun Wang
A hydrid microsphere Fe3O4@carbon@poly(InIII-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous InIII–carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m2/g of surface area and 0.2175 cm3/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@InIII-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.
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POLYMER BULLETIN
·
2015
·Vol. 72
·期 10
·2455-2469
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IF 1.438
Bai Liangjiu,Wang Dongju,Chen Hou,Li Dongxin,Xu Yuanyuan,Yu Lili,Wang Wenxiang
Abstract Peanut shell (PNS) was used to prepare a novel adsorbent to achieve resource recovery of the agricultural residue. The hydroxyl groups of peanut shell were turned into –C(CH 3 ) 2 –Br pendant groups to initiate polymerization of acrylonitrile. Graft copolymer peanut shell/polyacrylonitrile (PNS- g -PAN) was modified by hydroxylamine hydrochloride to transform the cyano groups into amidoxime (AO) groups. The modified copolymer of AO-PNS- g -PAN was used as adsorbent. The maximum adsorption capacity for Hg(II) was 4.45 mmol g −1 . The adsorption process fitted well the Freundlich isotherm model and followed pseudo-second-order model. The modified copolymer demonstrated its potential as an efficient adsorbent to solve the problem of Hg(II) contamination. Graphical abstract The peanut shell (PNS) macroinitiator was obtained by acylation of hydroxyl groups on the cellulose backbone of the peanut shell and initiated by Cu(0)-mediated RDRP of acrylonitrile. PNS- g -PAN was modified by NH 2 OH·HCl and used to remove heavy metal ions. The maximum adsorption capacity of Hg(II) was 4.45 mmol g −1 .
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2014
·Vol. 98
·期 12
·5665-5675
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IF 3.811
Xu Weiyuan,Cao Huazhen,Ren Guangwei,Xie Hujun,Huang Jianying,Li Shijun
A sorbent based on affinity ionic liquid (AIL), triazacyclononane-ionic liquid, was synthesized, characterized, and applied to the extraction of histidine (His)-tagged proteins from aqueous buffer to ionic liquid (IL) phase. The adsorbed His-tagged proteins could be back-extracted from the IL phase to the aqueous buffer with an imidazole solution. The specific binding of His-tagged proteins with AIL/IL could be affected by a few factors including the ionic strength and coordinated metal ions. In the case of His-tagged enhanced green fluorescent protein (EGFP), the maximum binding capacity of Cu 2+ -AIL/IL reached 2.58 μg/μmol under the optimized adsorption conditions. The eluted His-tagged EGFP kept fluorescent and remained active through the purification process. Moreover, a tandem extraction process successively using Cu 2+ -AIL/IL and Zn 2+ -AIL/IL systems was developed, which was proven very efficient to obtain the ultimate protein with a purity of about 90 %. An effective reclamation method for the AIL/IL extraction system was further established. The sorbent could be easily regenerated by removing metal ions with EDTA and the followed reimmobilization of metal ions. Easy handling of the presented M 2+ -AIL/IL system and highly specific ability to absorb His-tagged proteins make it attractive and potentially applicable in biomolecular separation.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2014
·
IF 2.93
Yufei Wang,Shuanjin Wang,Min Xiao,Dongmei Han,Yuezhong Meng
By the solution casting method, a novel porous membrane has been prepared for VRB by doping sulfonated poly(fluorenyl ether ketone) (SPFEK) with imidazole , and then imidazole was washed out by extraction with solution. The proton conductivity of porous membrane increased with increasing the content of imidazole, but proton/vanadium ion (H/V) selectivity decreased. Layer-by-layer (LbL) technique was used to improve the porous membrane with high selectivity. Moreover, the performance of VRB using SPFEK-20.7imidazole-(PDDA/PSS) 8 membrane which is doped with 20.7 wt.% content of imidazole and then removed imidazole, and then deposited with eight LbL bilayers exhibits the highest columbic efficiency (CE) of 92.5% at 30 mA cm −2 .
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APPLIED SURFACE SCIENCE
·
2013
·
IF 2.112
Zhike Wang,Cunling Ye,Xueyuan Wang,Juan Li
Imidazole-modified silica adsorbent with chloride as counter ion (SilprIm-Cl) was synthesized and characterized by scanning electron microscope, infrared spectra, thermogravimetric analysis, elemental analysis and BET analysis. The adsorption of chromium(VI) from aqueous solutions onto the SilprIm-Cl was investigated at varying pH, contact time, initial Cr(VI) concentration, adsorbent amount and temperature. The experimental results showed that the modification of silica with imidazole enhanced significantly the adsorption capacity for Cr(VI). The SilprIm-Cl was of primary anion-exchange adsorption nature, pH and excess Cl − ions in solutions affected significantly the adsorption of chromium(VI). The adsorption isotherms would be well defined with Langmuir model instead of Freundlich model. The adsorption process follows the pseudo-second-order kinetics. The maximum adsorption capacity of Cr(VI) of 47.79 mg g −1 with an initial Cr(VI) concentration of 150 mg L −1 was achieved at pH of 2.0. The adsorption–desorption experiments of the SilprIm-Cl exhibited that the adsorbent could be regenerated and reused eight times at least by simple washings with NaCl and water in turn.
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RSC Advances
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2015
·Vol. 5
·期 19
·14277-14284
·
IF 3.84
Mengshuai Liu,Fangxiao Wang,Lei Shi,Lin Liang,Jianmin Sun
The novel Zn-based task-specific ionic liquids (Zn-TSILs) catalysts were developed for the coupling of carbon dioxide and epoxides to form cyclic carbonates under mild reaction conditions without using additional organic solvents and cocatalysts. Due to the synergistic effects of the cation and anion in this catalytic system, excellent yields and selectivities to cyclic carbonates were achieved with high TOF values up to 794 h−1. Among the catalysts investigated, OH-containing Zn-TSILs showed better activity than COOH-containing Zn-TSILs, and [(CH2CH2OH)Bim]ZnBr3 was found to be the best. Additionally, the influences of CO2 pressure and catalyst concentration were also investigated over [(CH2CH2OH)Bim]ZnBr3. In addition, the rate constants as well as the activation energies for the cycloaddition reaction catalyzed by Zn-TSIL and TSIL were comparatively determined. The activation energy was calculated to be 34.1 kJ mol−1 for bare TSIL catalyst, whereas the Zn-TSIL reduced the activation energy value by 14.7 kJ mol−1. Moreover, the Zn-TSIL was easily recyclable without significant loss of activity, representing the exceptionally promising candidate for the effective fixation of CO2 to epoxides.
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JOURNAL OF HAZARDOUS MATERIALS
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2013
·
IF 3.925
Zhike Wang,Cunling Ye,Juan Li,Heping Wang,Han Zhang
The objective of this work was to improve the understanding the influence of the methyl group at different positions of imidazolium ring on the adsorption behaviors of imidazole-modified silica adsorbents. Five adsorbents named as SilprImCl, SilprM 1 ImCl, SilprM 2 ImCl, SilprM 4 ImCl and SilprM 1 M 2 ImCl were synthesized using imidazole , 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 1,2-dimethylimidazole, respectively. These adsorbents were characterized by scanning electron microscope, infrared spectra, thermogravimetric analysis, elemental analysis and BET analysis. Firstly, phenol, 2-nitrophenol (2-NP), 3-nitrophenol (3-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) were used as adsorbates to investigate the selectivity of SilprImCl and its adsorption capacities followed the order of 2,4-DNP ≫ 4-NP > 2-NP ≫ 3-NP > phenol. Therefore, 2,4-DNP was used to investigate the adsorption behaviors of the five adsorbents. It was inferred that the adsorbents are of primary anion-exchange and electrostatic nature. The electrostatic nature was affected significantly by the methyl group at different positions of imidazolium ring. The adsorbed amounts of 2,4-DNP decreased in the order of: SilprM 1 M 2 ImCl ≈ SilprM 1 ImCl > SilprM 4 ImCl > SilprM 2 ImCl > SilprImCl. The adsorption–elution experiments indicated that 2,4-DNP can be removed from aqueous solutions by a SilprM 4 ImCl packed column and the recovery of 91.6% was obtained. The adsorbent could be regenerated and reused ten times at least by simple washings with HCl and water in turn.
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ANALYTICAL CHEMISTRY
·
2013
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IF 5.695
Wenjie Ma,Qin Jiang,Ping Yu,Lifen Yang,Lanqun Mao
This study demonstrates the first exploitation of zeolitic imidazolate frameworks (ZIFs) as the matrix for constructing integrated dehydrogenase-based electrochemical biosensors for in vivo measurement of neurochemicals, such as glucose. In this study, we find that ZIFs are able to serve as a matrix for coimmobilizing electrocatalysts (i.e., methylene green, MG) and dehydrogenases (i.e., glucose dehydrogenase, GDH) onto the electrode surface and an integrated electrochemical biosensor is readily formed. We synthesize a series of ZIFs, including ZIF-7, ZIF-8, ZIF-67, ZIF-68, and ZIF-70 with different pore sizes, surface areas, and functional groups. The adsorption capabilities toward MG and GDH of these ZIFs are systematically studied with UV–vis spectroscopy, confocal laser scanning microscopy, and Fourier transfer-infrared spectroscopy. Among all the ZIFs demonstrated here, ZIF-70 shows excellent adsorption capacities toward both MG and GDH and is thus employed as the matrix for our glucose biosensor. To construct the biosensor, we first drop-coat a MG/ZIF-70 composite onto a glassy carbon electrode and then coat GDH onto the MG/ZIF-70 composite. In a continuous-flow system, the as-prepared ZIF-based biosensor is very sensitive to glucose with a linear range of 0.1–2 mM. Moreover, the ZIF-based biosensor is more highly selective on glucose than on other endogenous electroactive species in the cerebral system. In the end, we demonstrate that our biosensor is capable of monitoring dialysate glucose collected from the brain of guinea pigs selectively and in a near real-time pattern.
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Journal of Materials Chemistry B
·
2013
·Vol. 1
·期 25
·3202-3208
·
IF 0
Peng Fei Gao,Lin Ling Zheng,Li Jiao Liang,Xiao Xi Yang,Yuan Fang Li,Cheng Zhi Huang
A new type of coordination polymer sphere prepared by combining 1,1′-(1,4-butanediyl)bis(imidazole) (bbi) and ferrous ions has been demonstrated as a targeted delivery system for in situ encapsulating anticancer drugs. These stable coordination polymer spheres can be fabricated simply by a deposition method. Drugs, doxorubicin hydrochloride (DOX·HCl) for example, can be easily in situ encapsulated by simply mixing the drug with bbi ligand through the deposition method and results in a high drug loading efficiency up to 98% and a drug loading content of nearly 40%, which is remarkably high for not only metal–organic but also other materials. A noticeable feature of the drug loaded coordination polymer spheres is that they show sustainable drug release for several days due to their superior stability, and are sensitive to external pH owing to the coordination bonds. The drug can be released faster in mild acidic conditions in comparison to physiological acidity. By conjugating folic acid to the surface of the coordination polymer spheres, the vehicles can be taken up selectively by cancer cells through cell surface receptor-mediated mechanisms. Cell viability experiments with HeLla cells demonstrated the low toxicity of the delivery vehicles and the good anticancer efficacy of the drug-loaded coordination polymer spheres.
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RSC Advances
·
2015
·Vol. 5
·期 112
·92025-92032
·
IF 3.84
Jing Zheng,Liping Hu,Min Zhang,Jingli Xu,Pingang He
Rapid, sensitive, and accurate DNA detection is of great significance to meet the growing demand of disease diagnostics. Herein, an ultrasensitive and highly specific electrochemical sensing strategy for detection of hepatitis B virus (HBV) DNA hybridization in homogeneous solution was presented. In this sensing protocol, magnetic nanoparticles (MNPs) were prepared and modified with β-CD. MNPs/β-CD were then used for host–guest recognition, separation and detection. In the experiment, a stem-loop structured DNA was designed as the probe to indicate the occurrence of hybridization. It was labeled with dabcyl at the 5′-end as a guest molecule and Au nanoparticles at the 3′-end as an electrochemical tag. Initially, the DNA probe retained the stem-loop configuration, which shielded dabcyl from docking with β-CD/MNP in solution due to the steric effect. While in the presence of the complementary target DNA, the stem-loop structure of the probe was dissociated and the double-stranded DNA (dsDNA) was formed as a result of the hybridization. Consequently, dsDNA was linked to β-CD/MNP owing to the host–guest recognition between β-CD and dabcyl. Thus, the hybridization events could be sensitively transduced to electrochemical signals provided by Au nanoparticles. Au nanoparticles were then captured by the electrode through an external magnetic field. The designed sensor favored discrimination between the healthy and single-nucleotide polymorphism (SNP)-containing sequences. Under the optimized detection conditions, the sensing strategy showed high sensitivity and the detection limit was down to 9.930 × 10−13 M for a complementary HBV DNA sequence.
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BIOSENSORS & BIOELECTRONICS
·
2015
·
IF 6.409
Meiding Yang,Jian Chen,Huipeng Zhou,Wenying Li,Yan Wang,Juanmin Li,Cuiyun Zhang,Chuibei Zhou,Cong Yu
A benzoperylene probe excimer emission in an aqueous buffer solution is observed for the first time, and a novel ratiometric fluorescence method based on the probe excimer emission for the sensitive detection of heparin and heparinase is demonstrated. A negatively charged benzoperylene derivative, 6-(benzo[ghi]perylene-1,2-dicarboxylic imide-yl)hexanoic acid (BPDI), was employed. A polycation , poly(diallyldimethylammonium) chloride (poly-DDA), could induce aggregation of BPDI through noncovalent interactions. A decrease of BPDI monomer emission and a simultaneous increase of BPDI excimer emission were observed. Upon the addition of heparin, the strong binding between heparin and poly-DDA caused release of BPDI monomer molecules, and an excimer–monomer emission signal transition was detected. However, after the enzymatic hydrolysis of heparin by heparinase, heparin was hydrolyzed into small fragments, which weakened the competitive binding of heparin to poly-DDA. Poly-DDA induced aggregation of BPDI, and a monomer–excimer emission signal transition was detected. Our assay is simple, rapid, inexpensive, sensitive and selective, which could facilitate the heparin and heparinase related biochemical and biomedical research.
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