SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Can Wang,Zhenyuan Li,Ju Bai,Hongyan Liu,Xinbo Wang,Shuangjiang Luo
Membrane-based helium recovery from natural gas faces a major challenge due to membrane plasticization, which increases permeances but reduces selectivities. Thermal crosslinking has emerged as a promising approach to enhance the plasticization resistance of membranes by restricting segmental mobility and creating well-defined microporosity for gas separation. Herein, we develop novel dual thermally crosslinked asymmetric hollow fiber membranes (HFMs) using a 4,4′-diamino-2,2′-biphenyldicarboxylic acid-containing copolyimide. Decarboxylation-based dual crosslinking is achieved through heat treatment at various temperatures, resulting in the generation of C–C covalent bonds. The interchain distance increases from 5.33 to 5.76 Å, and the hierarchical pore size distributions exhibit ultra-micropore size between 5.6 and 6.8 Å as well as micropore size between 7.0 and 9.5 Å. Notably, the formation of stable C–C covalent bonds through dual crosslinking and the existence of bulky −CF 3 groups in the 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine moiety prevent substructure collapse by enhancing the chain rigidity and rotational barrier. Gas transport properties of the crosslinked HFMs are effectively tuned by adjusting the heat treatment temperatures. Particularly, the PI-TFMB-HF@400 membrane exhibits a He permeance of 25 GPU and He/CH 4 selectivity of 269. Additionally, the crosslinked HFMs exhibit enhanced plasticization resistance. The PI-TFMB-HF@400 membrane, for instance, shows only a 24 % decrease in mixed-gas CO 2 /CH 4 selectivity and an 80 % increase in mixed-gas [He/(CO 2 + CH 4 )] selectivity when exposed to a high-pressure (40 bar) ternary mixed-gas feed of He/CO 2 /CH 4 (0.3/49.7/50, v/v/v), and the mixed-gas [He/(CO 2 + CH 4 )] selectivity increases with temperature. The dual thermally crosslinked HFMs in this study demonstrate the potential for helium recovery from aggressive natural gas.
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CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Shuang Gao,Zhenxing Wang,Yan Chen,Yimu Wang,Qiyuan Fu,Changhao Feng
The efficient and rapid detection of triethylamine (TEA) is crucial in the field of gas sensors. Sensors fabricated using doped ternary metal oxides demonstrate high response, good stability, excellent gas selectivity, and reproducibility. In this study, NiFe 2 O 4 nanofibers doped with different concentrations of Yttrium (Y/Ni = 0 at%, 1.5 at%, 2.5 at%, 3.5 at% and 4.5 at%) were synthesized via electrospinning, and gas sensors fabricated from these materials were systematically analyzed for their gas-sensing performances. The results indicated that the gas-sensing properties of Y-doped NiFe 2 O 4 nanofibers were improved. Gas sensors based on Yttrium-doped NiFe 2 O 4 nanofibers with a Y/Ni ratio of 2.5 % (referred to as 2.5 % Y-NFO) exhibited the best performance, exhibiting a gas response of 39.3 for the detection of triethylamine at a concentration of 100 ppm at 125 °C. This response was about 3.1 times higher than pure NiFe 2 O 4 nanofibers. Additionally, the response time of 2.5 % Y-NFO is only 2 s, which is much faster than other reported TEA sensors. In addition, these gas sensors exhibit excellent repeatability, selectivity, and humidity resistance. Finally, the underlying mechanism responsible for the enhanced gas-sensing properties is comprehensively discussed. This study presents a simple, stable, and effective route for synthesizing Y-NiFe 2 O 4 nanofibers, thereby achieving excellent sensing performance for TEA detection.
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TALANTA
·
2025
·
IF 6.1
Liwei Hou,Xinyue Xu,Fengchun Tian,Yi Xu
The effective qualitative and quantitative detection of mixed components of volatile organic compounds (VOCs) with similar molecular structures has always been a challenge and hotpoint in the research. A novel quartz-crystal microbalance (QCM) nanocomposite sensor integrated with a surface-enhanced Raman scattering (SERS) detection platform for multi-component gas analysis was proposed and fabricated in this paper. MIL-100 (Fe)/PAN composite fibers were developed on QCM via electrospinning of polyacrylonitrile (PAN) and hydrothermal synthesis, addressing the integration issues of MIL-100 particles in devices while maintaining high specific surface area. The MIL-100(Fe)/PAN@QCM sensor can simultaneously collect QCM frequency responses and SERS spectra, enabling the quantitative and qualitative detection of toluene and benzaldehyde in mixtures. The linear response relationship between the frequency obtained by the QCM sensor and the concentration of toluene and benzaldehyde gases was in the range of 0–100 ppm, and the limits of detections were 0.57 and 0.86 ppm, respectively. Additionally, an algorithm, that considered the relationship among the QCM frequency response signal, intensity values of the characteristic peaks in the SERS spectra, and the gas concentration, was developed and applied to measure the mixed gases of toluene and benzaldehyde in the concentration range of 0–100 ppm. The relative standard deviations (RSDs) of spiked sample determinations were found to be in the range of 3–8%. This work provided a new method for the efficient and rapid detection of gas molecules with similar structures, which could be extended and applied to detect more multi-component gas mixtures.
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JOURNAL OF RARE EARTHS
·
2025
·
IF 7.2
Yan Liang,Hua Tang,Chunbo Ru,Xiaojian Zhao,Lu Tang,Yong Yang
Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity. However, phenomena including agglomeration, growth and structural damage of nanostructures are almost inevitable during the processes of device fabrication or sensing tests, which makes it difficult to exert their expected activity. To address this issue, rare earth metal oxide CeO 2 was chosen as the model material to explore confined nanostructures in resistive gas sensors. The experiment successfully achieves the preparation of confined CeO 2 nanoparticles film using a pulsed laser deposition combined with rapid annealing technology. It is found that the confined CeO 2 nanoparticles film enables the efficient detection of volatile organic compound triethylamine, demonstrating a significant response of 20 ( R a / R g ) towards 100 ppm triethylamine, a fast response of 2 s, excellent stability and selectivity. By in-situ confinement in porous carbon matrix, dispersion and fixation of CeO 2 nanoparticles can be achieved, thereby fully utilizing their high surface activity. In addition, the porous carbon matrix can serve as a transport pathway for the target gas molecules and electrons, enabling efficient gas-solid reactions and effective collection of gas sensing signals. More importantly, the confined CeO 2 nanoparticles film was grown in-situ on commercial alumina flats gas sensing substrate, which can be directly used as sensing layer for gas sensors. Based on first-principles calculations, the triethylamine sensing mechanism of the confined CeO 2 nanoparticles film was systematically analyzed at the atomic and electronic scale. This study offers new insights into enhancing the gas sensing performance of resistive gas sensors through confined nanostructures design.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Jiang Yang,Rongrong Fan,Shengke Li,Xiujuan He,Yingcheng Li,Wei Ding
Foam generated from solid foam sticks plays a crucial role in enhancing natural gas production by mitigating liquid accumulation in gas wells. Traditional solid foam sticks dissolve rapidly, releasing foam instantly, particularly at high downhole temperatures in gas wells. This necessitates frequent addition of surfactants to sustain foam generation. To address this issue, this study investigates the use of mesoporous silica nanocomposite to encapsulate the surfactant, cetyltrimethylammonium bromide (CTAB), as foam sticks, allowing for extended foam release. Mesoporous silica was synthesized through a sol–gel process involving a silica precursor and surfactant, utilizing alkali-acid catalysts in two steps. The resulting nanocomposite solid sticks were formed through aging and drying in a mold. The silica-surfactant nanocomposite was characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and small angle X-ray diffraction (SAXD). Experimental results demonstrated the successful encapsulation of 68.2 % surfactant into an average size of 50 nm nanosized silica capsules with a mesoporous structure. Quantitative determination of surfactant release over time in brine at a high temperature (130 °C) was determined through thermogravimetric analysis (TGA), which showed 6.3 % surfactant remained in nanocomposite after 3 days. Foam performance from the released surfactants was evaluated using a dynamic foam apparatus and blender test. The study showed that foam could be control-released over a period of 7 days through surfactant diffusion from mesoporous nanoparticles . The release of CTAB follows the first-order release kinetic model. This research provides a sustainable solution by utilizing mesoporous silica nanoparticles as carriers for surfactants, resulting in longer-lasting foam for the gas well deliquification and the enhancement of gas production.
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ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Xun Li,Hui Hu,Tian Tan,Mengjing Sun,Yuwen Bao,Zhongbing Huang,Sohail Muhammad,Xiaohong Xia,Yun Gao
Detection of leaks of flammable methane (CH4) gas in a timely manner can mitigate health, safety, and environmental risks. Zinc oxide (ZnO), a polar semiconductor with controllable surface defects, is a promising material for gas sensing. In this study, Ag–Ru co-doped into self-assembled ZnO nanorod arrays (ZnO NRs) was prepared by a one-step hydrothermal method. The Ag–Ru co-doped sample shows a good hydrophobic property as a result of its particular microstructure, which results in high humidity resistance. In addition, oxygen vacancy density significantly increased after Ag–Ru co-doping. Density functional theory (DFT) calculations revealed an exceptionally high charge density accumulated at the Ru sites and the formation of a localized strong electric field, which provides additional energy for the CH4 reaction with •O2– at the surface at room temperature. Optimized AgRu0.025–ZnO demonstrated an outstanding CH4 sensing performance, with a limit of detection (LOD) as low as 2.24 ppm under free-heat and free-light conditions. These findings suggest that introducing defects into the ZnO lattice, such as oxygen vacancies and localized ions, offers a promising approach to improving the gas sensing performance.
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Polymers
·
2024
·Vol. 16
·期 13
·1940
·
IF 4.7
Kuo Zhao,Yunbo Shi,Mingrui Cui,Bolun Tang,Canda Zheng,Qinglong Chen,Yuhan Hu
High sensitivity and selectivity and short response and recovery times are important for practical conductive polymer gas sensors. However, poor stability, poor selectivity, and long response times significantly limit the applicability of single-phase conducting polymers, such as polypyrrole (PPy). In this study, PPy/MoS2composite films were prepared via chemical polymerization and mechanical blending, and flexible thin-film resistive NO2sensors consisting of copper heating, fluorene polyester insulating, and PPy/MoS2sensing layers with a silver fork finger electrode were fabricated on a flexible polyimide substrate using a flexible electronic printer. The PPy/MoS2composite films were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy. A home-built gas sensing test platform was built to determine the resistance changes in the composite thin-film sensor with temperature and gas concentration. The PPy/MoS2sensor exhibited better sensitivity, selectivity, and stability than a pure PPy sensor. Its response to 50 ppm NO2was 38% at 150 °C, i.e., 26% higher than that of the pure PPy sensor, and its selectivity and stability were also higher. The greater sensitivity was attributed to p–n heterojunction formation after MoS2doping and more gas adsorption sites. Thus, PPy/MoS2composite film sensors have good application prospects.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2024
·
IF 8
Shenman Yao,Dehua Wang,Jiahao Li,Jianxian You,Yulin Zhu,Wufei Gong,Keng Xu,Yan Liang,Yanxing Yang,Yong Yang
Crystal facets engineering emerges as a potent strategy for modulating the surface properties and gas sensing performance of semiconductor metal oxides. However, related studies have primarily focused on conventional binary metal oxides gas sensing materials, while few studies have investigated the crystal facets-dependent gas sensing activity of recently developed ternary metal oxides. Herein, the effect of crystal facets on the gas sensing activity of Aurivillius-type layered perovskite structure material Bi 2 MoO 6 was studied. It was shown that Bi 2 MoO 6 nanosheets with {001} crystal facets exhibited significantly enhanced gas sensing activity with a high response value of 72 (R a /R g ) towards 100 ppm of triethylamine at relatively low working temperature of 250 °C, which was about 10 times higher than that of Bi 2 MoO 6 nanosheets with {010} crystal facets. The gas mechanism was elucidated at the atomic and electronic levels through first principles calculation combined with experimental characterization. On the one hand, the synergistic effect of Mo/Bi bimetallic sites makes the adsorption/charge transfer between {001} facets and triethylamine much stronger. On the other hand, {001} facets have abundant chemically adsorbed oxygen and oxygen vacancy on the surface, which act as the active species in gas sensing. These results not only significantly broaden the application scope of Aurivillius-type layered perovskite structure materials in the realm of gas sensing, but also provide important guidance for the study of gas sensing mechanism in ternary metal oxides.
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APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Zhikun Wang,Zhuo Chen,Ayesha Yousaf,Lan Wu,Guixin Jin,Zhigang Shao,Zhihua Zhao
Herein, a resistive gas sensor based on Molybdenum tri oxide (MoO 3 )/ 9 % mass fraction of multi-walled carbon nanotubes (MWCNTs-9) nanocomposites was developed by hydrothermal method to detect NH 3 gas at room temperature. According to the findings, outstanding resistance change rate of 187.5 % was observed in MoO 3 /MWCNT-9 sensor when exposed to 100 ppm NH 3 at room temperature (25 °C). In contrast, 8.2 % response rate was recorded for pure MoO 3 sensor when exposed to same condition and the response value of newly fabricated sensor was improved by about 22.9 times to unalloyed MoO 3 . In addition, the nanocomposite sensor consisting of MoO 3 /MWCNT-9 had demonstrated excellent selectivity, repeatability, and a high level of sensitivity in detecting low concentrations of NH 3 at low temperature. During experiment when the sensor desorbed NH 3 gas at room temperature, a certain instantaneous voltage was applied, which greatly reduces the sensor’s resistance recovery time to 90 s. MWCNTs’s doping decreased the operating temperature of MoO 3 and showed good gas sensitivity at room temperature. Finally, the results reveal that MoO 3 /MWCNT-9 nanocomposite-based sensor can be fruitful in the field of NH 3 monitoring.
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CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Xiao-Fang Lv,Xing-Ya Ni,Yan-Yun Xiao,Yang Liu,Ming-Guo Peng,Qian-Li Ma,Chuan-Shuo Wang,Shi-dong Zhou,Shang-Fei Song
The gas separation technology based on hydrate method offers several advantages, including a short process flow, simple equipment, no pollution, less corrosion, and lower energy consumption. It has a broad application prospect in the acid gas purification, biogas purification and CO 2 sequestration., etc. However, demanding hydrate formation conditions and lower gas separation effects constrain its application. Oil-water emulsion shows promise in improving mass and heat transfer efficiency, enhancing hydrate slurry fluidity, and reducing hydrate aggregates. Thus, this study investigates the effects of different oil–water ratios, promoter concentrations, and surfactants on hydrate formation and separation efficiency in an oil–water emulsion system. At an oil–water ratio of 1:1, the purification rate increased to 6.06, five times higher than in a pure water system. The addition of 1,3-Dioxolane (DIOX) facilitated bidirectional growth properties of hydrate formation on droplet surfaces, enhancing hydrate nucleation and formation, leading to a CO2 recovery increase to 87% with 1.5 wt% DIOX. Furthermore, lipophilic surfactants were more likely to promote hydrate slurry fluidization. The addition of Span80 reduced hydrate agglomeration and increased the rate of hydrate formation as concentration rose. The results suggest that adding DIOX and increasing the concentration of Span80 could improve the hydrate method’s separation efficiency at an oil–water ratio of 1:1.
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WATER RESEARCH
·
2024
·
IF 11.4
Zhengxuan Ji,Jiaxuan Wang,Zhongsen Yan,Caihong Liu,Zhe Liu,Haiqing Chang,Fangshu Qu,Heng Liang
Substantial volumes of hazardous shale gas produced water (SGPW) generated in unconventional natural gas exploration. Membrane distillation (MD) is a promising approach for SGPW desalination, while membrane fouling, wetting, and permeate deterioration restrict MD application. The integration of gravity-driven membrane (GDM) with MD process was proposed to improve MD performance, and different pretreatment methods (i.e., oxidation, coagulation, and granular filtration) were systematically investigated. Results showed that pretreatment released GDM fouling and improved permeate quality by enrich certain microbes’ community (e.g., Proteobacteria and Nitrosomonadaceae ), greatly ensured the efficient desalination of MD. Pretreatment greatly influences GDM fouling layer morphology, leading to different flux performance. Thick/rough/hydrophilic fouling layer formed after coagulation, and thin/loose fouling layer formed after silica sand filtration improved GDM flux by 2.92 and 1.9 times, respectively. Moreover, the beneficial utilization of adsorption-biodegradation effects significantly enhanced GDM permeate quality. 100 % of ammonia and 53.99 % of UV 254 were efficiently removed after zeolite filtration-GDM and granular activated carbon filtration-GDM, respectively. Compared to the surged conductivity (41.29 μS/cm) and severe flux decline (>82 %) under water recovery rate of 75 % observed in single MD for SGPW treatment, GDM economically controlled permeate conductivity (1.39-19.9 μS/cm) and MD fouling (flux decline=8.3 %-27.5 %). Exploring the mechanisms, the GDM-MD process has similarity with Janus MD membrane in SGPW treatment, significantly reduced MD fouling and wetting.
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ANALYST
·
2024
·
IF 3.6
Jiaying Wu,Shiyuan Xu,Xuemei Liu,Jingwen Zhao,Zhengfu He,Aiwu Pan,Jianmin Wu
Helicobacter pylori (H. pylori) is a globally widespread bacterial infection. Early diagnosis of this infection is vital for public and individual health. Prevalent diagnosis methods like the isotope 13C or 14C labelled urea breath test (UBT) are not convenient and may do harm to the human body. The use of cross-response gas sensor arrays (GSAs) is an alternative way for label-free detection of metabolite changes in exhaled breath (EB). However, conventional GSAs are complex to prepare, lack reliability, and fail to discriminate subtle changes in EB due to the use of numerous sensing elements and single dimensional signal. This work presents a dual-element multimodal GSA empowered with multimodal sensing signals including conductance (G), capacitance (C), and dissipation factor (DF) to improve the ability for gas recognition and H. pylori-infection diagnosis. Sensitized by poly(diallyldimethylammonium chloride) (PDDA) and the metal–organic framework material NH2-UiO66, the dual-element graphene oxide (GO)-composite GSAs exhibited a high specific surface area and abundant adsorption sites, resulting in high sensitivity, repeatability, and fast response/recovery speed in all three signals. The multimodal sensing signals with rich sensing features allowed the GSA to detect various physicochemical properties of gas analytes, such as charge transfer and polarization ability, enhancing the sensing capabilities for gas discrimination. The dual-element GSA could differentiate different typical standard gases and non-dehumidified EB samples, demonstrating the advantages in EB analysis. In a case–control clinical study on 52 clinical EB samples, the diagnosis model based on the multimodal GSA achieved an accuracy of 94.1%, a sensitivity of 100%, and a specificity of 90.9% for diagnosing H. pylori infection, offering a promising strategy for developing an accurate, non-invasive and label-free method for disease diagnosis.
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