SENSORS AND ACTUATORS B-CHEMICAL
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2022
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IF 9.221
Yuchen Zhu,Jian Xu,Haiyan Zhang,Aodong Zhang,Boxin Chen,Bin Zhao,Lei Li,Xuhong Qian,Ya Cheng,Fei Feng
A novel micro gas chromatography column (μGCC) with straight-sided elliptic microchannel cross sections was prepared by ultrafast laser-assisted chemical etching inside a glass substrate . The straight-sided elliptic cross sections resulted in a uniform distribution of the flow velocity field . This uniform distribution and the use of a microchannel with a consistent composition led to a uniform stationary phase coating. Upon the separation of a test mixture of C7–C11 alkanes, highly symmetrical chromatographic peaks were obtained. The tailing factors of the chromatographic peaks ranged from 0.95 to 1.05, which satisfies the relevant provisions of Pharmacopoeia of the People's Republic of China (ChP). The test results show that the improvement of the tailing factors is mainly due to the optimization of the cross-section structure rather than the optimization of the test conditions. Notably, due to the simple preparation processes and the low cost of the glass substrate, the total manufacturing cost of this novel μGCC is low.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2022
·
IF 9.221
Haiyan Zhang,Fei Feng,Yangyang Zhao,Bin Zhao,Lei Li,Dan Zheng,Xinxin Li
Increasing the aspect ratio of the microchannels of microfabricated gas chromatographic columns (μGCCs) can allow analytes to quickly reach equilibrium between the stationary phase and mobile phase , which helps improve their separation performance. In this paper, an all-silicon microfabricated gas chromatographic column (AS-μGCC) with a high aspect ratio was proposed and fabricated using deep reactive-ion etching (DRIE) and silicon direct bonding. Two AS-μGCCs with the lengths of 2 m and the aspect ratios of 6.6 (100 µm-width × 660 µm-depth) and 25 (30 µm-width × 750 µm-depth) were successfully fabricated. The effects of different aspect ratios on the column efficiency of AS-μGCCs were studied. A separation experiment showed that the column efficiency of the AS-μGCC with an aspect ratio of 25 (AS-μGCC-25) was 12 times higher than that of the AS-μGCC with an aspect ratio of 6.6 (AS-μGCC-6.6). The column efficiency of the AS-μGCC-25 was 1961 plates/m, and a heavy hydrocarbon mixture (C8–C20) could be separated using AS-μGCC-25 within 4.5 min
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JOURNAL OF MEMBRANE SCIENCE
·
2022
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IF 10.53
Shan Xu,Ning Zhao,Lei Wu,Shuanyan Kang,Zhiguang Zhang,Guolong Huo,Zhongde Dai,Nanwen Li
Tuning the relationship between the microporous structure of carbon molecular sieve (CMS) membranes and the corresponding gas permeability performance enables optimization for gas separation applications. The pre-crosslinked structure of the precursor plays a key role in improving the performance of the CMS membrane. Herein, the thermally crosslinkable brominated 6FDA-based polyimide (BMPI) by debromination is prepared and selected as the precursor to fabricate high performance CMS gas separation membranes . By heat-treating the BMPI membrane at 350 °C for 10 h, the debromination-induced crosslinking exhibited higher permeability over the uncrosslinked precursors, as it forms a pre-crosslinked structure that is more stable at 550 °C. A representative BMPI-350/10h-550 °C CMS membranes pyrolyzed at 550 °C had CO 2 and O 2 permeabilities of 11169 and 2182 Barrer with a CO 2 /CH 4 and O 2 /N 2 ideal selectivity of 26.5 and 5.4. These values are much higher than that of the un-crosslinkable precursor (6FDA-DAM) derived CMS membrane (P CO2 = 3465, α CO2/CH4 = 21.1). Even at the high carbonization temperature of 800 °C, the as-obtained CMS membrane still show a promising CO 2 permeability of 1119 Barrer and a CO 2 /CH 4 ideal gas selectivity of 41.2. Importantly, the excellent gas separation performance of CMS membranes obtained in this work exceeds the Robeson's upper-bound. This work outlines a new protocol to tailor CMS membrane microstructures to meet high permeability performance needs. These CMS membrane materials hold great potential in corrosive natural gas purification applications.
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高影响因子
APPLIED SURFACE SCIENCE
·
2022
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IF 7.392
Chengqin Dai,Maosheng Chen,Yujing Lin,Ruijuan Qi,Chunhua Luo,Hui Peng,Hechun Lin
Metal oxide semiconductor have been widely used as sensing materials for detecting various gases with trace concentrations. However, the sensing properties of layered cobaltites with metallic conductivity have not been investigated to date. In this work, we developed a convenient preparation method of Na x CoO 2 nanoflakes via aqueous ultrasonic exfoliation of Na x CoO 2 single crystals. The sensor based on Na x CoO 2 nanoflakes was fabricated, whose resistance is obviously smaller than that of the typical metal oxide based sensors. It shows less response to n -hexane, toluene, xylene, ammonia, methanol, ethanol and acetone. However, it exhibits excellent sensing performance to n -butanol and good moisture-resistance, and the sensitivity to 50 ppm n -butanol is up to 4.48 with the response time of 95 s and the recovery time of 154 s at the optimum working temperature of 200 °C. Owning to the high electric conductivity of Na x CoO 2 layers, the sensor presents a very low noise and a high signal-to-noise ratio value with the detection limit at ppb level. The layered cobaltites exhibit the rich phase diagram and the nanoflakes are versatile surface functionalization. This work provides insight for layered cobaltites to be employed as highly sensitive sensors.
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Separation Science Plus
·
2022
·Vol. 5
·期 9
·513-519
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IF 0
Yanni Huang,Jia Chen,Gafang Fu,Chi Zhang,Hongdeng Qiu
This work reported the preparation and evaluation of a 2D porous graphene as the stationary phase for gas chromatography with high-resolution performance from non-polar to polar structural isomers. As a result, the dynamically coated porous graphene capillary column has a film thickness of about 16 μm. After aging treatment at different temperatures, the porous graphene capillary column exhibited high thermal stability up to 300°C. In addition, the porous graphene capillary column has good column repeatability and reproducibility. The retention time RSDs are 2.61–3.90% ( n = 3) during the days and 4.58–4.78% ( n = 3) column-to-column. This work demonstrates the advantageous separation performance of a good potential for the porous graphene as a new stationary phase for gas chromatography analysis.
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CHEMOSPHERE
·
2022
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IF 8.943
Long Pang,Yanyan Zhang,Huiqiang Yang,Meijuan Zhang,Ziling Huang,Haozhao Wang,Baodan Jin
In this study, the gas-phase retention volume behavior of four highly volatile organophosphate esters (OPEs) on polyurethane foam (PUF) was studied using a frontal chromatogram. The breakthrough volumes ( V B ) of trimethyl phosphate (TMP), triethyl phosphate (TEP), tripropyl phosphate (TPrP), and tri-n-butyl phosphate (TnBP) were 0.33, 0.59, 10.5, and 32.4 m 3 , respectively. A significant negative correlation was found between the logarithm value of V B and the subcooled liquid vapor pressure ( P L ) with an r 2 of 0.905, indicating that the vapor penetration depends on both the volatility and total air volume. The enthalpy of desorption and vaporization (Δ H S −Δ H V ) showed a significant difference between the tested OPEs and polycyclic aromatic hydrocarbons (PAHs), revealing that the strength of the sorption interaction of the tested OPEs vapor on PUF should be different from that of PAHs. The PUF-air partition coefficients ( K PUF-air ) of the tested OPEs ranged from 4.3 to 8.1, which were lower than those of three-to four-ring PAHs (7.02–10.2) and organochlorines (8.01–9.72), revealing that the partition of highly volatile OPEs on PUF is lower than that of low-volatile compounds. The PUF/XAD cartridge improved the absorption efficiency of the tested OPEs; however, its sorptive capacity was still limited.
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PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
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IF 7.139
Qiang Sun,Gaoqiang Yuan,Zheng Liu,Jingbo Gao,Yiwei Wang,Xuqiang Guo,Lanying Yang
Recovery of hydrogen (H 2 ) from H 2 -containing gas mixtures has great significance for energy conservation, cost reduction and benefit increase. However, the common separation methods have the ubiquitous problem due to phase equilibrium principle and results in the conflict between H 2 concentration and H 2 recovery rate in the product gas. Consequently, an innovative conception of hydrate-membrane coupling approach is proposed in this work. In the separation process, hydration and membrane permeation two separation driving forces coexist to achieve the aim of strengthening mass transfer kinetics. H 2 and non-H 2 components (hydrocarbons) are synchronously and directionally selected by membrane and hydrate to improve different phase compositions . Therefore, the gas in feed side could keep relatively high two separation driving forces (H 2 fugacity and hydrocarbons fugacity). The results show that the coupling method could synchronously increase both the concentration and the recovery rate of H 2 in the product gas. At the same time, the volume and concentration of the hydrocarbons in hydrate both increases effectively. It indicates that hydrate and membrane separation methods support each other in the separation process. The hydrate-membrane coupling method fundamentally solves the issue of the decreasing driving force resulting from single separation method and phase equilibrium relationship.
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CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
YaHui Cai,ShuYi Ma,TingTing Yang,Li Wang,Ni Na Ma,Miao Miao Liu
The pure YVO 4 and heterostructured YVO 4 /V 2 O 5 gas sensitive materials were prepared by simple and economic hydrothermal path. A variety of characterization methods were used to study the morphology, specific surface area and binding state of YVO 4 /V 2 O 5 composites. The results show that the YVO 4 /V 2 O 5 composites has smaller particle size (reduced from 200 nm to 50 nm) and larger specific surface area, which is increased from 7.738 m 2 /g to 26.586 m 2 /g). Compared with pure YVO 4 , the n-type sensor based on YVO 4 /V 2 O 5 composites has higher response value (increased from 12.29 to 42.15), lower optimal operating temperature (reduced from 200 °C to 140 °C), and shorter response/recovery time (reduced from 11 s/25 s–6 s/14 s). The YVO 4 /V 2 O 5 composites gas sensor has excellent selectivity and good long-term stability for triethylamine gas. The study of gas sensing mechanism shows that n-n heterojunctions and large specific surface area conduce excellent gas-sensitive property of YVO 4 /V 2 O 5 composites. This work provides a valuable direction for low-cost preparation of TEA sensors with excellent performance and long-term stability.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Mengting Xu,Yujia Wang,Fangchun Chen,Jiaxuan Wang,Fangyin Dai,Zhi Li
High performance pressure sensing device fabricated by coating conductive polymers on flexible substrates attracts research focuses in the field of wearable devices currently. The most common method for polymerization of conductive polyaniline (PANI) in aqueous solution, generally causing problems of damage to flexible substrate, poor effect of polymerization and environmental pollution . In this study, a novel low-temperature gas–liquid interface polymerization method for PANI polymerization is developed to fabricate core–shell conductive fibrous membrane. By skillfully taking advantage of volatility of aniline monomer , layered conductive PANI grows vertically on the surface of electrospun fibers at gas–liquid interface instead of in traditional aqueous solution. The degree of PANI polymerization based on this method is controllable by glycerin, which can be analyzed by an established model. The sensor fabricated by this method demonstrates superior performance with a high sensitivity of 10.62 kPa −1 , fast response time (60 ms) and subtle detection limit (5.1 Pa) compared with that prepared by traditional liquid polymerization. This breathable sensor can detect human signal detection effectively, and develop a variety of intelligent applications. In brief, this work provides a novel strategy and facile technology for developing flexible intelligent devices with conductive polymers.
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CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jie Hu,Xueqing Xiong,Wangwang Guan,Haizhu Long
To realize a synergistic effect between composition engineering and morphology modulation, PdO–Fe 2 O 3 heterojunction architectures with various morphologies were fabricated by facile hydrothermal and solution impregnation methods. Afterwards, gas sensing devices were constructed from the as-prepared PdO–Fe 2 O 3 composites, and their parameters were systematically investigated. The obtained results revealed that all PdO–Fe 2 O 3 sensors exhibited excellent selectivity properties and high responses to target gases. Importantly, an urchin-like PdO–Fe 2 O 3 sensing device produced the largest response of 75 to 50 ppm hydrogen sulfide at a PdO concentration of 4 wt%, which was approximately four times greater than that of a spherical PdO–Fe 2 O 3 sensor. The urchin-like sensor was also characterized by the highest response recovery efficiency, water resistance, and long-term stability. Furthermore, the sensing mechanism of the fabricated PdO–Fe 2 O 3 composite-based gas sensors was discussed comprehensively.
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Yuan Liu,Binghui Xue,Yuyan Lai,Linkun Cai,Kun Chen,Panchao Yin
The strong inter-phase attraction is required for the effective and stable integration of inorganics and polymers in mixed matrix membranes (MMMs), which would impact the structures and microscopic dynamics of the two phases and cause unexpected deviation of MMM performance from original design; however, the understanding of its structure-property relationship is still poor. Herein, 2 nm coordination nanocage (CNC) with well-defined, monodispersed structure is complexed with poly(4-vinyl pyridine- r -n-butyl acrylate) (P4VP- co -PnBA) via both coordination and hydrogen bonding to afford model systems. The surface interaction between the two phases is quantified by the thickness of absorbed layers of polymers on CNC surface as well as the segmental dynamics of polymers. In broadband dielectric spectroscopy (BDS) studies, accelerated chain dynamics can be observed in the nanocomposites with loadings of CNC, which is originated from the frustrated packing of polymers absorbed on CNC surface. The co-effect of interfacial layer thickness and chain dynamics leads to the non-monotonic dependence of the MMMs’ gas permeabilities on CNC concentrations. The temperature dependence of their gas permeability and chain dynamics are both explored and the two processes are fully decoupled at temperatures higher than 333 K due to the weakening of multiple supramolecular interaction. Our discoveries provide microscopic and quantitative understanding on structure-property relationship of MMMs, which benefits directly to the rational design of polymer structures for optimized gas separation performance.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2023
·
IF 8.4
Zhixiang Hu,Licheng Zhou,Long Li,Jingyao Liu,Hua-Yao Li,Boxiang Song,Jianbing Zhang,Jiang Tang,Huan Liu
Colloidal quantum dots (CQDs) are promising materials candidates for next-generation semiconductor gas sensors, due to their high surface activity and solution-processability. Despite the improved sensitivity demonstrated by PbS CQDs, their long-term stability remains a challenge for practical applications. In this paper, we propose a stabilization strategy for PbS CQD gas sensors by using atomic-ligand engineering. The oleic acid ligands surrounding PbS CQDs are replaced by halide ligands (Cl – , Br – and I – , respectively) via a phase-transfer ligand exchange method. The sensitivity and long-term stability of the PbS CQD gas sensor towards nitrogen dioxide (NO 2 ) at room temperature are impressively improved. The excellent humidity stability of the iodine ligand exchanged PbS CQD gas sensor is also demonstrated. The mechanism is investigated by real-time electrical measurement, combined with operando diffuse reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. The results indicate that the large atomic radius and high binding energy of iodide ligands enhance surface passivation and provide favorable conditions for NO 2 adsorption and charge transfer. This study highlights the importance of surface ligand engineering in the development of practical CQD gas sensors.
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