RSC Advances
·
2016
·Vol. 6
·期 28
·23354-23359
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IF 3.289
Kai Xu,Zhenqi Jiang,Bo Feng,Aisheng Huang
It is well known that zeolite LTA membranes have poor acid resistance although they have been considered the best hydrophilic zeolite membranes for the dehydration of organic aqueous mixtures. In the present work, we develop a simple and effective road to enhance the acidic stability of the zeolite LTA membrane through the depositing of a graphene oxide (GO) layer as an acid-resisting barrier on the surface of the zeolite LTA membrane. A relatively thin (about 5.5 μm) but dense and firm LTA@GO composite membrane is obtained by using dopamine as a covalent linker between the zeolite LTA and GO layers. The presence of the protective GO layer effectively inhibits the degradation of the zeolite LTA membrane by acetic acid, which greatly enhances its acid-resistant stability, leading to a high selectivity and stability for the dehydration of acetic acid. For the separation of 95 wt% acetic acid/water mixture at 333 K, the separation factor and flux of the LTA@GO composite membrane are about 400 and 1.5 kg m−2 h−1, respectively, and keep almost constant for 168 h.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Changyan Zhou,Huiping Zhang,Ying Yan,Xinya Zhang
The technique -- chemical vapor deposition (CVD) is known for its atom economy, simple preparation steps in catalyst preparation as well as high catalytic activity of the catalysts made by this method and was applied to the preparation of copper modified catalysts supported on Linde Type A zeolite membrane/paper-like stainless steel fibers (LTA/PSSF) in this work. A series of catalysts were prepared for acetone oxidation . Several techniques were carried out to characterize the catalysts including X-ray diffraction (XRD), scanning electron microscope (SEM), energy disperse X-ray spectrometer (EDS) mapping, X-ray photoelectron spectrum (XPS), N 2 adsorption and desorption isotherms as well as H 2 -temperature programmed reduction (H 2 -TPR). The results of the SEM showed that the zeolite membrane grew successfully on the surface of PSSF support, and the EDS illustrated that the copper oxides coated on the support materials uniformly. The Cu/LTA/PSSF catalyst prepared by CVD was tested in a zeolite membrane reactor . The experimental results revealed that higher loading results in better catalytic activity as the 10% Cu/LTA/PSSF-CVD presented the highest catalytic activity in acetone oxidation (90% of acetone converted at 300 °C) when compared with 5% Cu/LTA/PSSF-CVD (322 °C) and 1% Cu/LTA/PSSF-CVD (305 °C). The CVD method is proved to be a feasible and powerful way to prepare the catalyst. The experimental results suggested that the T90 of the 10% Cu/LTA/PSSF-CVD is slightly higher than that of 10% Cu/LTA/PSSF- impregnation (IM, 310 °C) and much better than that of granular Cu/LTA catalyst (346 °C), though the T50 (268 °C) is slightly lower than 10% Cu/LTA/PSSF-IM (260 °C).
研究领域:
催化化学
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材料科学
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环境工程
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 26
·12279-12286
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IF 3.3
Chaowen Liu,Mudi Xin,Xuejing Zhang,Chunlu Wang,Limei Qiu,Guangtong Xu
As an alternative to conventional cryogenic distillation, LTA zeolites act as cost-effective adsorbents for the adsorptive separation of ethylene and ethane. In this approach, the thermodynamic and kinetic separation of ethylene and ethane by LTA zeolites with regulated particle sizes and pore structures has been studied. Herein, LTA zeolites, with different particle sizes ranging from 0.82 μm to 4.96 μm and a pore diameter distribution concentrated around 4.16–5.07 Å, were prepared using the hydrothermal method followed by an ion-exchange procedure. The results indicated that variation of the zeolitic particle size and the Ca2+ exchange rate has a great influence on the separation process, including the selectivity of C2H4 and the breakthrough time intervals of C2H4 and C2H6. Several issues, including the intracrystalline diffusion, accessibility of active sites, reinforced interaction between adsorbents and adsorbates, and the confined space in the zeolitic channels, were investigated to explain the altered nature of the separation performance. The optimized separation performance was achieved using LTA zeolites with a particle size of 0.82 μm or with an ion-exchange rate of 69.13% and a pore diameter distribution of 4.94 Å.
研究领域:
化学工程
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材料科学
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吸附分离技术
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DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2025
·
IF 5.1
Qianqian Bian,Xiaoxia Zhang,Xiaodi Zhang,Naiyue Zhang,Yifeng E,Peng Chen,Li Li,Kun Qian
Rapid and accurate detection of glutamic acid has always been our focus. Herein, we propose a non-enzymatic electrochemical sensor based on low-cost double transition metal oxides to detect glutamic acid efficiently. In this study, LTA nano-zeolite cages are synthesized by hydrothermal method. To further improve the conductivity, TiO 2 and Co metal nanoparticles are combined with nano-zeolite cages with multiple electrocatalytic sites to form TiO 2 -Co/LTA NPs. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and high-resolution projection electron microscopy (TEM) were used to characterize the materials before and after adsorption and oxidation of glutamic acid. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to test the oxidation and adsorption properties of the modified sensor after adding glutamic acid. Under the optimal pH condition, the sensor detection range is 3.0 × 10 −12 –3.0 × 10 −8 M and the detection limit (LOD) can reach 1.0 × 10 −12 M. In addition, the sensor has good selectivity for glutamic acid, even in the presence of multiple other amino acids. The practical application shows that the sensor can be used to detect glutamic acid in milk, seawater and serum samples with a recovery rate of 90.0 % to 110.0 % and RSD <4 %. We anticipate that this work will provide new ideas for the development of third-generation non-enzymatic sensors for glutamic acid monitoring.
研究领域:
材料科学
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分析化学
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生物医学工程
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2024
·
IF 8.4
Xiaowei Wu,Yuqin Li,Xinwei Chen,Xiaoyan Wang,Jianggui Tan,Tian Gui,Xiangshu Chen,Hidetoshi Kita,Haijiao Xie
Compared with conventional LTA membranes (Si/Al ratio = 1), Si-rich LTA membranes with higher Si/Al ratios are considered to exhibit better hydrothermal stability under high-temperature and water-rich conditions. In this work, high-performance Si-rich LTA membranes were successfully prepared on rough macropore alumina tubes via a hydroxyl radical route in a short synthesis time of merely 8 h. The membrane had the highest Si/Al ratio of 1.63 in the reported LTA membranes. The crystallization processes of Si-rich LTA membranes fabricated with and without hydroxyl radicals were investigated systematically. The role of hydroxyl radicals was detailly discussed by density-functional theory (DFT), SEM, XRD, EDX, EPR, and fluorescence characterizations. Results demonstrated that hydroxyl radicals first promoted the depolymerization of Si substances and then enhanced the Si–O–Si bond formation, thus resulting in an increasing crystallization rate and a higher framework Si/Al ratio of Si-rich LTA membrane. The fabricated Si-rich LTA membrane exhibited outstanding water selectivity with the water content in permeate of exceeding 99.96 wt% and excellent permeation flux of higher than 2.50 kg m −2 h −1 in the case of a 90 wt% EtOH/H 2 O mixture at 348 K. Additionally, the membrane displayed remarkable hydrothermal stability by vapor permeation (VP) test with equimolar of EtOH/H 2 O and MeOH/H 2 O mixtures at a high temperature of 423 K for 120 h, respectively. The Si-rich LTA membranes fabricated with hydroxyl radical showed excellent reproducibility, suggesting that these membranes had a broad promising prospect for separation dehydration of organic solvents even under high-temperature and high-water-content conditions.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2016
·Vol. 100
·期 11
·5079-5088
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IF 3.376
Liu Di,Guo Hua,Zheng Wenyun,Zhang Na,Wang Tianwen,Wang Ping,Ma Xingyuan
Heat-labile enterotoxin (LT) is a protein toxin produced by enterotoxigenic Escherichia coli (ETEC). As a bacterial toxin, LT holotoxin can enter intestinal epithelial cells and cause diarrhea. In addition, LT is also a powerful mucosal adjuvant capable of enhancing the strong immune responses to co-administered antigens. However, the LT immunological mechanism is still not clear in some aspects, especially with the respect to how the LTA subunit functions alone. Here, we discovered that the A 2 domain of LTA could carry a fluorescent protein into cells, whose function is similar to a cell-penetrating peptide. The transmembrane-transporting ability of the A 2 domain is non-specific in its cell-penetrating function, which was shown through testing with different cell types. Moreover, the LTA 2 fusion protein penetrated a fluorescently labeled cell membrane that identified LTA 2 internalization through membrane transport pathways, and showed it finally localized in the endoplasmic reticulum. Furthermore, low-temperature stress and pharmacological agent treatments showed that the LTA 2 internalization route is a temperature-dependent process involving the clathrin-mediated endocytosis and the macropinocytosis pathways. These results could explain the internalization of the LTA subunit alone without the LTB pentamer, contributing to a better understanding of LTA working as a mucosal adjuvant; they also suggest that the A 2 domain could be used as a novel transport vehicle for research and treatment of disease.
研究领域:
微生物学
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免疫学
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细胞生物学
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药理学
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产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Jian Zhang,Ya Wang,Lei Dong,Zhuwen Chen,Yanding Wang,Mei Hong
Micrometer-sized hierarchical LTA-type zeolite crystals with uniform embedded macropores were synthesized via steam-assisted conversion (SAC) of spherical mesoporous silica particles (MSPs) impregnated with alkaline aluminate. The one-pot synthesis was achieved by direct transformation without the need of organic structure directing agents or pre-formed seeds. The obtained cubic hierarchical NaA zeolite materials were 2–5 μm in size which possessed a core-shell structure with a microporous wall in the shell and multi-hollow macropores about 400 nm in the core. Time-series studies revealed the in situ dissolution–crystallization formation mechanism, in which the mesoporous silica particles functioned as silica source as well as “space-filling” template. When the starting MSPs were pre-loaded with metal precursors, multi-hollow zeolite nanoreactor crystals with encapsulated metals were successfully synthesized by this strategy. The present study provides an organic-free way to fabricate hierarchical aluminosilicate zeolites with embedded macropore system.
研究领域:
材料科学
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化学合成
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纳米技术
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催化化学
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无机化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2023
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IF 3.9
Lan Zhang,Keli Zhang,Shengle Kang,Shanshan He,Xiang Dong,Yan Zhao,Fangfang Li,Qihong Cen
Crystalline celluloses , such as microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC), which are originated from biomass, were utilized as templates to prepare hierarchical LTA zeolites . The effect of both size and surface properties of crystalline cellulose on the zeolite synthesis were carefully discussed. As-prepared zeolite based on surface-modification NCC showed hierarchical porous structure with monolithic morphology inherited from nanocrystalline cellulose. Its specific surface area was measured to be 18.3 m 2 /g, which was approximately 3.4 times that of the traditional zeolite A (Z0, 5.4 m 2 /g). Owing to its unique structure, ZNSC facilitated fast Cd(II) adsorption with the adsorption equilibrium time shortened by 81.3%. Kinetics study revealed that intraparticle diffusion was significantly enhanced and the effective diffusion coefficient increased by near 5 times. Furthermore, the maximum adsorption capacity achieved by ZNSC was 324.3 mg/g at 283 K, as calculated from the Langmuir model, which was 1.3 times that of Z0. These results are obtained when the grain size of ZNSC is larger than that of Z0, reflecting the superiority of the hierarchical structure in enhancing adsorption performance and thus providing a facile yet robust strategy for designing hierarchically structured zeolites for rapid and efficient wastewater treatment .
研究领域:
材料科学
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环境工程
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化学工程
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产品关联
DOI
高影响因子
CHINESE JOURNAL OF STRUCTURAL CHEMISTRY
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2024
·
IF 5.9
Yongheng Ren,Yang Chen,Hongwei Chen,Lu Zhang,Jiangfeng Yang,Qi Shi,Lin-Bing Sun,Jinping Li,Libo Li
The identical molecular size and similar physical properties of carbon dioxide (CO 2 ) and acetylene (C 2 H 2 ) make their adsorptive separation extremely challenging to achieve with most adsorbents. Reports on the separation of CO 2 and C 2 H 2 mixtures by zeolites are even rarer with the mechanism of adsorptive separation requiring further exploration. In this paper, we report that ion modulation of zeolite 5A promotes the difference in kinetic diffusion of CO 2 and C 2 H 2 , realizing the inverse separation of zeolite from selective adsorption of C 2 H 2 to selective adsorption of CO 2 . Creating a compact pore space restricting the orientation of gas molecules enables charge recognition. The positive electrostatic potential at the pore openings was utilized to hinder the diffusion of C 2 H 2 between the cages while ensuring the transfer of CO 2 , increasing their diffusion differences in pore channels and leading to the CO 2 /C 2 H 2 kinetic selectivity of 31.97. Grand canonical Monte Carlo (GCMC) simulation demonstrates that the CO 2 distribution in K-5A- β is significantly higher than that of C 2 H 2 . Dynamic breakthrough experiments verify the excellent performance of material in practical CO 2 /C 2 H 2 separation, for CO 2 /C 2 H 2 (50/50 and 1/99, V/V) mixtures can be separated in one step, thus directly generating high purity C 2 H 2 (> 99.95%), which provides a promising thought for the zeolite-based separation of CO 2 and C 2 H 2 .
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
Jianzhong Yu,Song Ye,Yanling Shi,Huazhen Liao,Deping Wang
In this research, the Linde Type A (LTA) zeolites were firstly synthesized with hydrothermal method and then the Ag + ions were introduced into LTA through Ag + -Na + exchange process, and the luminescent Ag 3 n + nanoclusters can be formed inside the sodalite cages under heat treatment at 300–700 °C, which exhibited yellow-greenish emission under UV excitation. The XRD , SEM and TEM measurements were carried out to study the influence of Ag + loading and heat treatment on the structure of LTA zeolite. The spectral measurement indicated the optimized Ag + -exchange level and heat treatment temperature, and the redshift of emission peak with increasing Ag + -loading or heat treatment temperature can be attributed to the interaction between Ag 3 n + nanoclusters . When exposing in air, the emission intensity of Ag 3 n + nanocluster was two orders of magnitude decreased while the re-heating can partially recover its emission. According to the XPS measurement and the AP calculation, this reduction in emission intensity can be assigned to the oxidation of silver atoms that constitute Ag 3 n + nanoclusters .
研究领域:
材料科学
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纳米技术
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光致发光
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无机化学
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沸石化学
✓ 已验证
DOI
高影响因子
Results in Engineering
·
2025
·
IF 7.9
Qing Jing,Jian Ye,Sili Chen,Xukai Li,Liang Guo,Weimin Zheng,Jinsong Wang,Yanjiao Gao
Radioactive wastewater discharge increased continuously with the widespread utilization of nuclear energy around the world, among which 137 Cs is one of the most critical radionuclides requiring removal. Traditional Lind Type A (LTA) zeolite exhibits promising adsorption potential for ¹³⁷Cs, however its slow adsorption kinetics remains a limitation. A hierarchically porous LTA zeolite (JLTA) via modification with Dimethyl Diallyl Ammonium Chloride (DMDAAC) was developed. Mesopores of JLTA were constructed effectively via hydrophobic groups of DMDAAC while preserving its intrinsic micropores, which was confirmed by XRD, SEM-EDS, BET, and FT-IR. Optimal conditions of JLTA’s adsorption performance (pH = 6, dosage = 5 g/L, T = 298 K) was gained during systematic investigations under varying pH, dosage, contact time, initial Cs⁺ concentration, and temperature. Cs⁺ adsorption by JLTA was primarily due to ion exchange with supplementary electrostatic attraction, following monolayer adsorption, which was revealed via kinetic models, adsorption isotherms, and characterization analyses. The intra-particle diffusion-controlled process achieved equilibrium within 5 min, demonstrating remarkably accelerated kinetics. A maximum adsorption capacity of 249.390 mg/g of JLTA was exhibited.
研究领域:
环境科学
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材料化学
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核化学
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吸附技术
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DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2024
·
IF 15.7
Kai Fan,Qinming Wu,Shuo Liu,Haiyu Kong,Sen Wang,Eduard Kunkes,Trees De Baerdemaeker,Andrei-Nicolae Parvulescu,Nils Bottke,Toshiyuki Yokoi,Dirk E. De Vos,Xiangju Meng,Weiping Zhang,Feng-Shou Xiao
Adjusting location and distribution of Al sites in the zeolite framework is critical for catalysis, and typical strategies include using zeolites as starting Al source. However, this approach is still challenging for aluminosilicate ITH zeolite. Herein, the distribution of Al species in the framework of ITH was efficiently regulated by implementing LTA zeolite as the aluminum source added in the starting gels (LTA-ITH). The obtained LTA-ITH zeolites have similar nanosheet morphology, textual parameters, and acidic properties to those of conventional ITH synthesized from boehmite (C-ITH), while the results of 27 Al MAS NMR spectra and 1-hexene cracking indicate that they have a different Al distribution. The use of LTA zeolite in starting gel is favorable for the formation of more Al species in sinusoidal and straight channels, compared with the C-ITH. Catalytic tests in the conversion of methanol to light olefin showed that LTA-ITH exhibited enhanced catalyst lifetime and propene selectivity compared with the C-ITH, which is reasonably attributed to the different locations of Al species in their respective ITH frameworks.
研究领域:
化学
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催化科学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）