JOURNAL OF MOLECULAR LIQUIDS
·
2020
·
IF 5.065
Tiantian Ping,Yu Dong,Shufeng Shen
Nonaqueous CO 2 absorbents, composed of secondary alkanolamines and 2-alkoxyethanols, have attracted much attention for an energy-efficient CO 2 capture process. In this work, densities and viscosities of partially CO 2 -loaded mixtures of 2-(butylamino)ethanol (BAE) + 2-butoxyethanol (EGBE) and 2-(ethylamino)ethanol (EAE) + EGBE were measured at atmospheric pressure over the temperature range of (293.15 to 353.15) K with amine mass fraction ( w 1 ) of (0.10, 0.30 and 0.50) containing various CO 2 loading. With increasing CO 2 loadings, significant increases in both density and viscosity were observed. Dimensionless ρ loaded · ρ CO2-free −1 and η loaded · η CO2-free −1 from the CO 2 -free and CO 2 -loaded systems were fitted by proposed correlations as a function of temperature, amine concentration and CO 2 loading. The calculated values of density and viscosity from the correlations are in good agreement with the experimental results, with AADs within 0.15% and 1.60% for density and viscosity respectively. The dramatic increase in viscosity of carbonated solutions was interpreted by the intermolecular interactions and the formation of ionic products in the mixtures based on the FTIR spectral results.
研究领域:
化学工程
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2025
·
IF 13.1
Tao Wang,Qiao Yu,Zhilin Chen,Chao Xiao,Shuming Peng
The active phase for methane combustion is still in debate. Low-temperature CO-FTIR spectroscopy was used to probe the working surface state on a series of Pd/Al2O3 (PdAl) and Pd/silicalite-1 (PdSil) catalysts with different starting states: oxidized, reduced (R), reoxidized (Ro). The surface of prereduced PdAl (Pd0) is transformed to an oxidized state (PdOx) with a CO stretching vibration (νCO) at ∼2157 cm–1 when it is aged in the methane oxidation mixture. The aging-induced transformation from Pd0 to PdOx occurred at 250 °C or above. Although PdSil has multiple kinds of PdOx entities, prereduced PdSil also transformed into PdOx. For PdAl(4)-R-A250, XRD patterns suggest weak bulk oxidation of Pd0 at 250 °C, XPS spectra indicate 28% of surface Pd0 atoms are oxidized, but CO-FTIR spectra confirm all the “top surface” Pd0 atoms are oxidized. It demonstrates the advantage of CO-FTIR spectroscopy in probing the top surface state. Finally, a direct correlation between operando FTIR spectroscopy and low-temperature CO-FTIR spectroscopy was established. Operando FTIR spectra over PdSil during methane oxidation at 250 °C gives two bands at 2124 cm–1 (CO–Pd+) and 2161 cm–1 (CO–Pd2+). After cooling in nitrogen, CO-FTIR spectra give two similar bands at 2134 cm–1 and 2157 cm–1. The “working surface state” can be preserved in CO-FTIR. For PdAl(4), operando FTIR spectra at 250 and 300 °C give no bands of adsorbed CO. Adding CO into the methane oxidation mixture resulted in a single CO–Pd2+ band at 2163 cm–1, which is in accord with their CO-FTIR spectra. For operando FTIR spectroscopy, the observation of the bands of adsorbed CO depends on the accumulation of the CO intermediates, but their accumulation is limited to reaction temperatures below 300 °C and to PdSil (not PdAl). These limitations make low-temperature CO-FTIR spectroscopy more general and sensitive.
研究领域:
催化化学
·
材料科学
·
环境化学
·
光谱学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers in Molecular Biosciences
·
2022
·
IF 6.113
Yaguchi Momo,Jia Xiaodan,Schlesinger Ramona,Jiang Xiue,Ataka Kenichi,Heberle Joachim
Direct optical activation of microbial rhodopsins in deep biological tissue suffers from ineffective light delivery because visible light is strongly scattered and absorbed. NIR light has deeper tissue penetration, but NIR-activation requires a transducer that converts NIR light into visible light in proximity to proteins of interest. Lanthanide-doped upconversion nanoparticles (UCNPs) are ideal transducer as they absorb near-infrared (NIR) light and emit visible light. Therefore, UCNP-assisted excitation of microbial rhodopsins with NIR light has been intensively studied by electrophysiology technique. While electrophysiology is a powerful method to test the functional performance of microbial rhodopsins, conformational changes associated with the NIR light illumination in the presence of UCNPs remain poorly understood. Since UCNPs have generally multiple emission peaks at different wavelengths, it is important to reveal if UCNP-generated visible light induces similar structural changes of microbial rhodopsins as conventional visible light illumination does. Here, we synthesize the lanthanide-doped UCNPs that convert NIR light to blue light. Using these NIR-to-blue UCNPs, we monitor the NIR-triggered conformational changes in sensory rhodopsin II from Natronomonas pharaonis (NpSRII), blue light-sensitive microbial rhodospsin, by FTIR spectroscopy. FTIR difference spectrum of NpSRII was recorded under two different excitation conditions: (ⅰ) with conventional blue light, (ⅱ) with UCNP-generated blue light upon NIR excitation. Both spectra display similar spectral features characteristic of the long-lived M photointermediate state during the photocycle of NpSRII. This study demonstrates that NIR-activation of NpSRII mediated by UCNPs takes place in a similar way to direct blue light activation of NpSRII.
研究领域:
生物物理学
·
光学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Particuology
·
2015
·
IF 2.11
Jie Li,Lianxi Chen,Xi Li,Chaocan Zhang,Zhenhui Liu
In this study, we present a facile method to prepare thiocyanato-functionalized porous silica nanospheres. Thiocyanato functionalized silica shells were coated on positively charged cetyltrimethylammonium bromide (CTAB) micelles via hydrolysis and condensation of (3-thiocyanatopropyl)triethoxysilane (TCPTES), the CTAB cores were removed subsequently to form thiocyanato-functionalized porous silica nanospheres. We demonstrate that the contents of the thiocyanato groups within the functionalized porous silica nanosphere frameworks gradually diminished as a function of hydrothermal treatment time at 100 °C until complete removal, confirmed by TGA and FTIR spectra. The data indicate that extended operation at relatively elevated temperatures may lead to the decomposition of the thiocyanato functional groups. In addition, at a lower CTAB concentration (0.0009 M), non-porous thiocyanato functionalized silica nanospheres were formed. However, increasing the CTAB concentration to 0.01 M resulted in porous nanospheres inferring that a CTAB concentration threshold is needed to form thiocyanato-functionalized porous silica nanospheres.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
SCIENCE & JUSTICE
·
2013
·
IF 1.151
Yuanfeng Wang,Ran Du,Tianshui Yu
Introduction In this paper, the authors presented a case of acrylamide poisoning in a middle-aged woman who had underwent unsuccessful cosmetic surgery six years earlier. The victim was told that the product that had been injected into her face was Restylane®, which mainly contained sodium hyaluronate and was the first and only Food and Drug Administration (FDA)-approved dermal filler for lip enhancement in the USA for more than 20 years. Widespread facial infections occurred several years post-injection; finally, the victim had to undergo removal surgery. Acrylamide poisoning was strongly suspected based on the victim's clinical manifestation. The product that had been injected into the victim's face was probably polyacrylamide hydrogel-based product, which had been prohibited by the State Food and Drug Administration (SFDA) in China in 2006. To confirm this suspicion, a systematical method was established to differentiate varieties of cosmetic surgery products and identify residential acrylamide. Methods The removed objects, original products and a certified reference sample of Restylane® were collected for examination. A direct microscopic examination was applied as a rapid screening method. Fourier transform infrared (FTIR) microspectroscopy analysis was subsequently performed to distinguish the main components from each sample. Automated solid phase extraction , ultra high performance liquid chromatography (SPE UHPLC) analysis was ultimately utilised and optimised to detect the residual acrylamide. Chromatographic separation was achieved on an ACQUITY UHPLC HSS T3 column. The mobile phase consisted of 0.01% aqueous formic acid solution and acetonitrile . The tunable UV (TUV) detection wavelength was at 202 nm. Results The microscopic examination indicated that different samples had different morphological characteristics , depending on their main components. The FTIR spectrum showed that different polymers could be distinguished according to the C O stretching vibration (1655 cm − 1 ), N H bending vibration (1540 cm − 1 ) and C O stretching vibration (1078 and 1045 cm − 1 ). The UHPLC results demonstrated that the calibration curve was linear in the range of 0.5–20.0 μg/mL, with a correlation coefficient of 0.999. The average recoveries of the method were 99–107% with an RSD of 1.6–6.3%. The detection limit was 0.1 μg/mL (S/N = 3). The analytical time was 6 min per sample. Acrylamide was detected in the allegedly Restylane® injection. Conclusions This systematical method provides a rapid, accurate and sensitive determination of polyacrylamide and residual acrylamide. The microscopic and FTIR spectroscopic examinations help to verify the existence of polyacrylamide quickly and easily. The optimised SPE UHPLC-TUV method offers a simpler and more sensitive approach to confirm the amount of acrylamide, comparing to the methods in the literature.
研究领域:
医学毒理学
·
分析化学
·
整形外科
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymer Chemistry
·
2016
·Vol. 8
·期 5
·865-878
·
IF 5.687
Gehong Su,Tao Zhou,Xifei Liu,Yanan Ma
In this study, the micro-dynamics mechanism of the volume phase transition behavior of the poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (PNIPAM-co-HEMA) hydrogel was investigated by temperature-dependent FTIR spectroscopy in combination with the perturbation correlation moving window (PCMW2D) technique and generalized two-dimensional correlation analysis. In conventional 1D FTIR spectra analysis, Boltzmann fitting curves showed that the volume phase transition temperature and the phase transition degree of the PNIPAM-co-HEMA hydrogel were lower than those of the pure PNIPAM hydrogel. They also showed that the PHEMA segments exhibit a similar “phase transition” behavior to the PNIPAM segments, which can be ascribed to the driving effect of the phase transition of PNIPAM segments. Furthermore, we found that the rate at which water molecules were expelled out of the gel structure during phase transition changed in an anti-S shape. PCMW2D spectra revealed that the phase transition can be divided into two processes (named I and II) upon heating, and further determined the temperature regions of processes I and II to be 21.8–31.4 °C and 31.4–36.5 °C, respectively. Finally, generalized 2D correlation analysis found that both processes I and II can be further divided into nine steps. From the deduced nine steps of process I, the significant role of PHEMA in the phase transition of PNIPAM segments was revealed. As for the deduced nine steps of process II, the driving effect of the phase transition of PNIPAM segments for PHEMA segments was confirmed.
研究领域:
材料科学
·
生物医学工程
·
高分子化学
✓ 已验证
DOI
高影响因子
Soft Matter
·
2015
·Vol. 11
·期 35
·7059-7065
·
IF 4.029
Lei Hou,Peiyi Wu
The UCST-type transition of poly(acrylamide-co-acrylonitrile) (P(AAm-co-AN)) (molar fraction of AN: 13.3%; PDI = 3.2) in H2O and D2O is explored and compared by applying turbidity, DLS as well as FTIR measurements. The transition temperature of P(AAm-co-AN) in D2O is observed to be almost 10 °C higher than that in H2O at the same concentration, demonstrating a dramatic solvent isotope effect. Such a phenomenon could be rooted from a stronger interaction among polymer chains in D2O than in H2O, as indicated from DLS results. It is also observed in second-derivative analysis of FTIR spectra in the ν(CO) region, where all CO groups participate in the formation of inter-/intra-chain hydrogen bonds (CO⋯H–N) in D2O while there is still part of relatively “free” CO groups in H2O. Moreover, we find in the temperature-dependent FTIR spectra that CN groups exhibit hydrating behavior while CO groups present increased inter-/intra-molecular hydrogen bonding interaction (CO⋯H–N) upon cooling, revealing the later process to be the driving force of the UCST-type transition.
研究领域:
高分子化学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
AICHE JOURNAL
·
2025
·
IF 4
Hui Wang,Yifan Jin,Yaxin Jin,Siyu Kuang,Tianxiang Yan,Xinyue Wang,Xiao Wang,Wenquan Cui,Sheng Zhang
Electrochemical carbon dioxide reduction reaction (CO 2 RR) is one of the most prospective strategies to achieve carbon neutrality. Multi-carbon compound (C 2+ ) products have higher commercial value and wider applications, among which ethanol is a widely used chemical feedstock and high energy density fuel. Here, we prepared nitrogen-doped carbon nanofibers containing copper-zinc double atoms using the electrospinning technique and controlled the content of both metal atoms by varying the calcination temperature. This catalyst exhibited ultra-high selectivity for ethanol at low potentials. Ethanol selectivity at −0.3 V versus RHE was more than 60% with the total alcohol selectivity of over 80%. Meanwhile, we explored the ethanol production pathway by combining density-functional theory (DFT) and ATR-FTIR spectroscopy, and found that OCCO* intermediates were most abundant for the optimal ratio of Cu to Zn atoms, lowering the energetic barriers to ethanol formation, and thus improving the selectivity of ethanol production.
研究领域:
材料科学
·
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
MINERALS ENGINEERING
·
2019
·
IF 3.315
Fei Lyu,Wei Sun,Sultan Ahmed Khoso,Chenyang Zhang,Runqing Liu,Li Wang,Jiande Gao
In this study, propyl gallate (propyl 3,4,5-trihydroxybenzoate; PG) was introduced as a collector for scheelite. The adsorption mechanism on the scheelite surface was investigated by computational and experimental methods, including first principle calculations and Fourier transform infrared (FTIR) spectroscopy. Flotation experiments were conducted to investigate the flotation performance of PG on scheelite. Ethyl p-hydroxybenzoate (EPHB) and ethyl 3,4-dihydroxybenzoate (EDHB), acting separately as collectors for scheelite, were also investigated for comparison. Our results consistently demonstrated that PG chemisorbed onto the scheelite surface by forming a five-member ring through its ortho oxygens. As speculation, the chelating ability of PG was greater than that of EDHB, and EPHB cannot coordinate to Ca(II), which was in excellent agreement with FTIR results. The flotation results showed that PG exhibited an excellent collecting ability for scheelite, followed by the weaker collecting ability of EDHB. EPHB had nearly no ability to collect scheelite, thus confirming the first principle calculation and FTIR analysis. In addition, PG has a stronger ability to collect scheelite than BHA without activation by any metallic ions. Overall, PG is a promising scheelite collector for application and the activate polyphenolic hydroxyl groups offer a new insight for the development of flotation collectors.
研究领域:
矿物加工工程
·
理论化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuhang He,Hua Ke,Yangcheng Lu
Controlled alcoholysis of ethylene–vinyl acetate copolymer (EVA) is very important both to industry and academic research. To this end, accurate kinetic model is an important tool, but traditional methods for studying reaction kinetics involving polymers are usually laborious and time consuming due to the need of product purification. Therefore, we developed a new method to study the alcoholysis of EVA with 32 mol% ethylene content based on in situ FTIR spectroscopy. The feasibility and accuracy of this method was carefully studied. A kinetic model for predicting reaction rate was obtained using this method. The applicability of the kinetic model was further verified by performing flow alcoholysis in microflow reactor. It was found that this kinetic model is pretty accurate for conversions up to around 60 %, even at a relatively high temperature. The in situ FTIR method may also be suitable for monitoring industrial production process and other alcoholysis systems like PVA.
研究领域:
高分子化学
·
化工工程
·
分析化学
✓ 已验证
DOI
高影响因子
CHEMICAL GEOLOGY
·
2018
·
IF 3.57
Yong Yuan,Xixi Cai,Bin Tan,Shungui Zhou,Baoshan Xing
Solid-phase humic substances (also termed humins, HMs) are the largest fraction of humic substances (HSs) in soils and sediments, which are recently shown to be capable of mediating electron transfer in many key biogeochemical processes. However, the redox properties of HMs remains poorly investigated, likely due to their structural complexity and the lack of efficient methodology. Herein, an electrochemical in situ FITR spectroscopic (EC-FTIRS) technique coupled with two-dimensional correlation spectroscopy (2D-COS) was employed for the first time to study the redox process of complex HMs at a molecular level. In situ FTIR identified that the IR bands of quinone and phenolic moieties in the HMs were potential dependent, suggesting that they were the main redox sites in response to the redox transformation of the HMs. Meanwhile, In situ FTIR characterizations showed that the significant variations in IR bands positioned at ~1500 and ~1470 cm −1 in response to the applied potentials, providing evidence for the presence of quinone radical and dianion intermediates during the redox process. The 2D-COS analysis was used to further explore variations in infrared intensities as a function of the potentials applied to reduce or oxidize the HMs, which indicated the occurrence of the typical redox reactions of quinone in the HMs. These results improve our understanding on the redox mechanism of HMs at the molecular level and have significant implication for in-depth understanding of biogeochemical processes.
研究领域:
环境科学
·
分子生物学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2024
·
IF 3.3
Tao Wang,Benlong Yu,Long Mu,Zhilin Chen,Chao Xiao,Shuming Peng
The palladium oxide phase (PdOx) plays a critical role in catalytic methane oxidation and CO oxidation reactions. Precise characterization of supported PdOx by CO-FTIR spectroscopy is often accompanied by the reduction of PdOx by CO. Lowering the CO partial pressure to 0.05% CO/N2 (0.5 mbar) and the adsorption temperature to −130 °C is a proper condition to inhibit the reduction completely. Then CO-FTIR spectroscopy was conducted on a series of supported PdOx catalysts. We find that CO adsorbed on coordinatively unsaturated Pd atoms (Pdcus) on the PdOx surface gives three adsorption bands at ∼2145 cm–1. Three types of surface Pdcus atoms with different degrees of coordination unsaturation (types I, II, and III) exist in supported PdOx catalysts; their νCO are located at 2133, 2145, and 2160 cm–1, respectively. The order of coordination unsaturation of surface Pdcus should be type III < type II < type I. Since νCO of surface Pdcus is between νCO of Pd2+(CO) and Pd+(CO), the effective charge of surface Pdcus is 1 < n < 2. For small PdOx clusters in zeolite-supported PdOx catalysts, surface Pdcus atoms with more coordination unsaturation (i.e., step, edge, and corner sites) are more abundant, leading to greater IR intensity of adsorbed CO.
研究领域:
催化化学
·
表面化学
·
光谱学
·
材料科学
·
环境化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）