JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2014
·
IF 3.107
Junying Zhao,Hongzhang Chen
The effect of small phenolic compounds in pretreated stover on celluase activity is crucial but has not yet been fully elucidated. This work investigated the effects of both phenolic acid and phenolic aldehyde on cellulase activity. The model substances of small phenolic compounds identified in steam exploded corn stover were used to examine their individual effects on cellulase activity. It was found that phenolic aldehyde significantly inhibited cellulase activity at 0.05–8 g/L. However, phenolic acids might have a concentration-dependent effect on cellulase activity: significant inhibition at 0.05 g/L and slight stimulation at 2–4 g/L. Small phenolic compounds mixture might also have a concentration-dependent effect on cellulase activity: significant stimulation at 2–8 g/L and slight inhibition at 0.05–1 g/L. The small phenolic compounds in pretreated stover were proven to be able to significantly stimulate enzymatic hydrolysis of stover. On the basis of these results, it is proposed that the concentration-dependent effects of small phenolic compounds on cellulase activity should be considered while removing them after pretreatment.
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ANALYST
·
2013
·Vol. 139
·期 1
·242-250
·
IF 3.969
Juan Zhang,Wenpeng Zhang,Tao Bao,Zilin Chen
A novel capillary with hydroxyapatite (HAP) as the stationary phase was prepared for open-tubular capillary electrochromatography (OT-CEC). To immobilize HAP, a mussel-inspired polydopamine method was utilized to modify the capillary firstly, generating a polydopamine layer; and then a layer of HAP would be formed on the polydopamine layer by a biomineralization process, to produce a HAP-modified capillary (HAP@capillary). Scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS) provided evidence of nanostructured HAP grown on the surface of the capillary wall. The electroosmotic flow (EOF) characteristic of the HAP@capillary was investigated by varying the percentage of acetonitrile and pH value of the buffer with thiourea as a marker, and a pH-dependent EOF from anode to cathode was observed. The HAP@capillary exhibits high column efficiency for methylbenzene, up to 151 138 plates per meter. Different kinds of compounds including alkylbenzenes, phenols and amines have been successfully separated by the HAP@capillary in CEC mode. The HAP@capillary also possessed good separation ability in capillary liquid chromatography (CLC) mode because of the relatively large ratio of HAP in the capillary; however, the separation efficiency was not as good as that in CEC mode. The reproducibilities of the HAP@capillary were evaluated, and the relative standard deviations were found to be lower than 5%.
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TALANTA
·
2013
·
IF 3.498
Jin Li,Xuebin Zhang,Yuxin Liu,Hongwu Tong,Yeping Xu,Shaomin Liu
In this paper, a highly selective sample cleanup procedure combing dummy molecular imprinting and solid-phase extraction (DMIP–SPE) was developed for the isolation and determination of bisphenol A (BPA) in tap water. The novel hollow porous dummy molecularly imprinted polymer (HPDMIP) was prepared adopting a sacrificial support approach, using tetrabromobisphenol A (TBBPA), whose structure was similar to that of BPA, as the dummy template and mesoporous MCM-48 nanospheres as the support. Owing to a very short distance between the binding sites and the surface, a large surface area and a good steric structure to match its imprint molecules, the maximum adsorption capacities ( Q max ) of the dummy-imprinted and non-imprinted sorbents for BPA were as high as 445 and 340 μmol g –1 , respectively, and the adsorption reached about 73% of Q max in 10 min. Meanwhile, a method was developed for the determination of BPA using HPDMIP as a solid-phase extraction enrichment sorbent coupled with HPLC . Under the optimum experimental conditions, HPDMIP exhibited satisfactory results in the enrichment and determination of BPA in tap water with a recovery rate of 95–105%, and relative standard deviations of below 6%, and it can achieve a limit of detection as low as 3 ng mL −1 . The developed extraction protocol eliminated the effect of template leakage on quantitative analysis and could be applied for the determination of BPA in complicated functional samples.
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CHINESE JOURNAL OF CHEMISTRY
·
2013
·Vol. 31
·期 9
·1228-1233
·
IF 0.917
Guofei Jin,Zhongduo Yang,Weiwei Xue,Jie Sheng,Yin Shi,Xiaojun Yao
New isoconessimine derivatives were synthesized from conessine ( 1 ) and evaluated as acetylcholinesterase (AChE) inhibitors. The derivatives were prepared via two reaction steps, N -demethylation and nucleophilic substitution. All of the synthesized derivatives exhibited more potential anti-acetylcholinesterase activities than conessine ( 1) (IC 50 =16 µmol·L −1 ) and isoconessimine (2) (IC 50 >300 µmol·L −1 ). Compound 7b (3 β -[methyl-[2-(4-nitrophenoxy)ethyl]amino]con-5-enine) showed the most potent inhibitory activity with an IC 50 of 110 nmol/L which is close to that of reference compound huperzine A (IC 50 =70 nmol/L). The mode of AChE inhibition by 7b was reversible and non-competitive. In addition, molecular modeling was performed to explore the binding mode of inhibitor 7b at the active site of AChE and the results showed that 7b could be docked into the acetylcholinesterase active site and compound 7b had hydrophobic interactions with Trp279 and Leu282.
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Environmental Progress & Sustainable Energy
·
2013
·Vol. 33
·期 3
·814-823
·
IF 0.865
Ruihua Huang,Bingchao Yang,Qian Liu,Yanping Liu
The simultaneous adsorption of phenol and Cr(VI) from aqueous solution onto this activated carbon/chitosan composite was investigated. This composite almost removes phenol and Cr(VI) simultaneously in a pH range of 2–5. The removals of phenol and Cr(VI) reached up to 95% when phenol and Cr(VI) concentrations were less than 50 mg/L and 200 mg/L, respectively. The presence of phenol reduced Cr(VI) adsorption, while the presence of Cr(VI) had no evident effect on phenol adsorption. The adsorption for both Cr(VI) and phenol followed pseudo-second-order kinetics in single or mixedsystems. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 814–823, 2014
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CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Tongtong Han,Yuanlong Xiao,Minman Tong,Hongliang Huang,Dahuan Liu,Luyan Wang,Chongli Zhong
A series of CNT@MIL-68(Al) composites with different carbon nanotubes (CNTs) loadings have been synthesized and characterized by SEM, TEM, PXRD, FT-IR, TGA, and N 2 adsorption. As evidenced from SEM and TEM images, the incorporation of CNTs can result in better dispersity of MIL-68(Al) in composites and smaller particle size than pure MIL-68(Al). Adding appropriate amounts of CNTs increases both the BET surface areas and the total volume of small micorpores (<16 Å), leading to largely improved performance of adsorptive removal of phenol from aqueous solution. In the industrial concentration range of phenol, the adsorption capacity of 0.75% CNT@MIL-68(Al) was improved up to 188.7% compared with the pristine MIL-68(Al), possibly due to the increase of small micropores introduced by the incorporation of CNTs. Regeneration experiments demonstrated that the composites are stable with good regenerability for at least five cycles. This work shows that the composites formed by the combination of CNTs and MOFs may find promising applications in liquid phase adsorption.
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JOURNAL OF CHROMATOGRAPHY A
·
2013
·
IF 4.612
Xiao-Dong Cheng,Xi-Tian Peng,Qiong-Wei Yu,Bi-Feng Yuan,Yu-Qi Feng
The present study described the preparation of a novel phosphate ester-bonded silica (PES) stationary phase based on “thiol-ene” click chemistry. The composition of the surface grafts of PES stationary phase was determined by elemental analysis and solid state 31 P MAS NMR. Due to its hydrophilic phosphate-ester groups and short hydrophobic alkyl chains, the PES stationary phase exhibited dual retention mechanism via complexation and hydrophobic interactions with phenols. Benefiting from this special interaction mechanism, the newly synthesized PES stationary phase showed better selectivity in the separation of phenols compared to commercial octadecylsilyl-bonded silica (C18) columns. Furthermore, the separations of 10 nucleosides and nucleobases on the PES stationary phase were achieved in both reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode.
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JOURNAL OF CHROMATOGRAPHY A
·
2013
·
IF 4.612
Guangxin Yuan,Yongbo Peng,Zhenghua Liu,Jieya Hong,Yao Xiao,Jialiang Guo,Norman W. Smith,Jacques Crommen,Zhengjin Jiang
In order to prepare zwitterionic HILIC monolithic columns with high polarity, the highly hydrophilic monomer N , N -dimethyl- N -acryloyloxyethyl- N -(3-sulfopropyl)ammonium betaine (SPDA) and crosslinker N , N ′-methylenebisacrylamide (MBA) were employed for developing a novel sulfoalkylbetaine type stationary phase. The polymerization parameters were systematically optimized in order to obtain a satisfactory performance for column permeability, mechanical stability, hydrophilicity, efficiency and selectivity. Compared to the previously reported poly( N , N -dimethyl- N -methacryloxyethyl- N -(3-sulfopropyl)ammonium betaine- co -ethylene dimethacrylate) (poly(SPE- co -EDMA)) monolith and the poly(SPDA- co -EDMA) monolith that we developed, a significantly enhanced hydrophilicity was obtained on the poly(SPDA- co -MBA) monolithic column, illustrated by the lowered critical composition of the mobile phase corresponding to the transition from the HILIC to the RP mode. Excellent permeability, reproducibility and stability were achieved on this optimized poly(SPDA- co -MBA) monolith. A column efficiency of 70,000 plates/m was obtained for the analysis of bases at a linear velocity of 1.95 mm/s. As expected, by studying the influence of mobile phase pH and salt concentration on their retention, a weak electrostatic repulsion interaction for negatively charged analytes was also observed at low organic solvent content on the poly(SPDA- co -MBA) monolithic column. The final optimized poly(SPDA- co -MBA) monolith exhibited good selectivity for a series of polar compounds, such as phenols, bases, benzoic acid derivatives, small peptides, urea and allantoin.
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Journal of Materials Chemistry A
·
2013
·Vol. 1
·期 31
·8876-8887
·
IF 0
Yuchao Wang,Shengyang Tao,Yonglin An,Shuo Wu,Changgong Meng
Inspired by the structure and function of coral in nature, a series of composite electrode materials were prepared via depositing conducting polymers, such as polyaniline (PANi), polythiophene (PTh) and polypyrrole (PPY), on the surface of monolithic coral-like porous carbon (MC). MC with a specific surface area as high as 1125 m2 g−1 was prepared by a facile dual-templating approach. A thin layer of the conducting polymer was formed on the carbon surface. The constitutive properties including the morphology, pore size and specific area were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller measurement (BET), respectively. The electrocapacitive properties of electrode materials were evaluated using cyclic voltammetry and galvanostatic charge–discharge cycling in a three electrode system. Compared with MC, the specific capacitances of composite materials had an obvious shift, which reached 1488 F g−1 at a high current density (1.0 A g−1) in an aqueous H2SO4 electrolyte. The coral-like hierarchical porous structure of the carbon favoured the diffusion of the electrolyte ions, hence not only improving the energy storage capacity but also enhancing the power density. The energy density reached 49.5 W h kg−1, even when the maximum power density was 12 000 W kg−1. In addition, such a composite electrode material also showed considerable electrochemical stability, with at least 76.7% of the capacitance being retained after 1000 cycles.
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RSC Advances
·
2015
·Vol. 5
·期 125
·103203-103209
·
IF 3.84
Qin Zhang,Po Yang,Yuyuan Deng,Chengxi Zhang,Rongqi Zhu,Yi Gu
This work aims to search the key starting materials and the key step of benzoxazine synthesis using primary amine, phenol and formaldehyde as the starting materials. The reaction kinetics were investigated by gas chromatography. The kinetic parameters of benzoxazine formation, such as reaction order, rate constant and activation energy, were found to approximately equal those of phenol consumption, which revealed that phenol was the key starting material and played an important role in the synthesis of benzoxazine. Furthermore, step 2, the reaction between formaldehyde–amine derivatives and phenol for the production of a mannich base was the controlling step. This improved insight into the benzoxazine synthesis is expected to help researchers explore novel benzoxazines and control their synthesis.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2015
·Vol. 17
·期 29
·19401-19409
·
IF 4.493
Feng Quan,Yun Hu,Xingchen Liu,Chaohai Wei
In this study, mesoporous SBA-15 bifunctionalized with cetyl and amino groups (cetyl/amino-SBA-15) was successfully prepared by a post-synthesis grafting method. Detailed characterization by XRD, FT-IR, N2 adsorption–desorption and elemental analysis confirmed that cetyl/amino-SBA-15 still retained a long-range ordered hexagonal mesostructure. Cetyl and aminopropyl groups were simultaneously functionalized on the surface of SBA-15. The adsorption capacity of cetyl/amino-SBA-15 was much higher than the arithmetic sum of those of cetyl-SBA-15 and amino-SBA-15 due to the cooperative effect of hydrogen bonding/electrostatic interaction between 4-nonylphenol (4-NP) and aminopropyl groups and hydrophobic interactions between 4-NP and cetyl groups. The effects of the dosage and mole ratio of cetyl and amino groups on the adsorption properties of cetyl/amino-SBA-15 for 4-NP were also investigated. Cetyl/amino-SBA-15 exhibited excellent adsorption capacity over a wide range of pH values and cetyl/amino-SBA-15(3.2/0.8) displayed the highest adsorption capacity up to 120 mg g−1. Furthermore, cetyl/amino-SBA-15 exhibited high adsorption selectivity for 4-NP against phenol as well as high reusability, showing great potential for applications in wastewater treatment.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2015
·
IF 3.091
Fengzhen Zhang,Chaohai Wei,Yun Hu,Haizhen Wu
The studies in ozonation catalysis present a trend in development of advanced oxidation processes (AOPs) applied to the wastewater treatment. The zinc ferrite (ZnFe 2 O 4 , ZFO) catalysts were synthesized hydrothermally (ZFO-H) and using the citrate sol–gel (ZFO-C) method with their characterization by XRD, Raman spectrum, SEM, XPS and FT-IR techniques. The objectives of this study include examining the performance of the catalysts in oxidation of phenol and pollutants in biologically treated coking wastewater (BTCW), compared to non-catalytic ozonation, and evaluating the ozonation reaction kinetics. The changes in the composition of BTCW on course of treatment were determined by ultraviolet–visible (UV) absorption and three-dimensional excitation–emission matrix spectroscopy (3DEEMs) analyses. The experimental results showed the ZFO-H catalyst accelerating the degradation of phenol for about 1.5 times as compared to non-catalytic ozonation. The catalytic activity of ZFO-H surpassed that of ZFO-C in phenol removal, attributed to the larger contact surface area and higher surface hydroxyl group density. The higher catalytic activity of ZFO-H was also confirmed by the ability of decomposing ozone and generating hydroxyl radicals ( OH). The empirical model developed in the research indicates the catalyst concentration and the ozone concentration to be the most significant factors of the reaction apparent rate; the role of pH appeared to be minor. The presence of catalysts leads also to a higher mineralization efficiency of BTCW pollutants compared to non-catalytic ozonation. The UV and 3DEEMs analysis demonstrated effective removal of the aromatic and conjugated structural compounds in BTCW by catalytic ozonation. The performance of the catalysts is determined primarily by their synthesis method defining the surface properties.
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