| 1. |
- Ma, Chunyan, et al.
(författare)
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Thermodynamic study of imidazolium halide ionic liquid–water binary systems using excess Gibbs free energy models
- 2023
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 391, Part B
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the excess Gibbs free energy models, i.e., non-random two-liquid (NRTL) model and electrolyte NRTL model, including the original one and those with new strategies (association or hydration), were used to describe the macroscopic properties and interpret the microstructure of ionic liquid (IL) - H2O binary systems, clarifying the role of IL association and ion hydration in model development. To provide systematic data for model development, the enthalpy of mixing of three imidazolium-based IL-H2O systems containing the same cation but different sizes of anions, i.e., Cl−, Br−, and I−, were measured. The models were developed and evaluated based on the newly measured data and the osmotic coefficient from the literature. The results reveal that the model reflecting the intrinsic mechanism of dissociation and hydration gives the best modeling results; and the ionic strength and the degree of IL dissociation as a function of water content can be predicted using the newly established model. The study clarifies the significance of IL association and anion hydration in model development and quantitatively demonstrates how water content influences the microstructure and real species in IL-H2O systems.
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| 2. |
- Dong, Yihui, et al.
(författare)
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Excellent Trace Detection of Proteins on TiO2Nanotube Substrates through Novel Topography Optimization
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:50, s. 27790-27800
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Tidskriftsartikel (refereegranskat)abstract
- For improving the surface-enhanced Raman scattering (SERS) performance of nanomaterials to achieve trace detection of proteins and complex biological systems, structural and topographical control is one of the important strategies. In this work, a facial and effective method to optimize the topography of TiO2 nanotube arrays (TNAs) is demonstrated, together with a significant enhancement of the SERS performance of cytochrome C (Cyt C) on TNAs. An enhancement factor (EF) up to 104, which is obtained with the newly developed method on the basis of the quantification of atomic force microscopy (AFM)-measured interaction force, is achieved, corresponding to a superior detection limit of Cyt C down to 10-7 M. The main reason is that adjusting the fluoride contents in an electrolyte (from 0.4 to 0.1 wt %) can reduce the content and sizes of cracks, as well as the tube ruptures of TNAs, where the fluoride content at 0.2 wt % can successfully provide the excellent and optimized topography of TNAs. The TNAs with the optimized topography, especially those with larger tube diameters, demonstrated the importance of structural integrity on a remarkably excellent SERS performance in the trace detection of proteins. The proposed method will stimulate the development and optimization of the active substrate on the SERS applications in biology, bioanalysis, and nanoscience. © 2020 American Chemical Society.
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| 3. |
- Jiang, Guancong, et al.
(författare)
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Critical Role of Carbonized Cellulose in the Evolution of Highly Porous Biocarbon : Seeing the Structural and Compositional Changes of Spent Mushroom Substrate by Deconvoluted Thermogravimetric Analysis
- 2020
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 59:52, s. 22541-22548
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Tidskriftsartikel (refereegranskat)abstract
- Structural optimization of activated carbon (AC) mainly relies on experience, which depends on the intrinsic structure of biochar, processing conditions, and the interplay of both parties. A fundamental understanding of the pore structure evolution related to the intrinsic structure and composition remains a challenge. In this work, spent mushroom substrate, a rapidly growing byproduct of the mushroom cultivation industry, is used as model biomass to prepare AC under CO2 activation. The structure and composition of the AC products with different activation durations were systematically analyzed with several characterization techniques including N2 adsorption–desorption, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. A multipeak separation method is developed that enables quantitative analysis of carbonized lignin and carbonized cellulose. A peak area ratio parameter is proposed to describe the retention of cellulose. It is revealed that higher retention of carbonized cellulose corresponds to a larger Brunauer–Emmett–Teller (BET) surface area, demonstrating the dominant role of cellulose in the pore structure development process. This work not only provides a qualitative correlation between cellulose and rich porous structure but also offers a new quantitative tool to understand the structure–composition relationship during the pore evolution process.
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| 4. |
- Sun, Yunhao, et al.
(författare)
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How to detect possible pitfalls in ePC-SAFT modelling : Extension to ionic liquids
- 2020
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 519
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Tidskriftsartikel (refereegranskat)abstract
- An ion-specific electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) has been developed to describe the thermodynamic and transport properties of ionic liquids (ILs) for developing IL-based technologies to separate CO2 from gas mixtures. However, as it has been pointed out previously, SAFT-based models can lead to a pitfall, manifesting as an additional fictitious liquid-liquid critical line connected to an additional mechanically stable critical point when modeling pure substances. In this work, a method for detecting a pitfall in ILs was developed, where an expression with ionic term for calculating the critical point with ePC-SAFT was derived and an algorithm for detecting the additional fictitious phase equilibrium for ILs was proposed. The pitfall occurrence for an extended set ILs taken from our previous work was investigated. It shows that a pitfall occurs only for one single IL among all 96 ILs in the temperature and pressure range of interest. For [C8mpy][BF4], at 290.27–291.78 K, a pitfall may occur at the pressures of interest; at 273.15–290.20 K, it may occur at any given pressure. The ion-specific ePC-SAFT parameters for [C8mpy]+ may therefore need to be modified in the future when more reliable experimental results are available for parameter fitting.
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| 5. |
- Wang, Hui, et al.
(författare)
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Experimental and theoretical study on ion association in [Hmim][halide] + water/isopropanol mixtures
- 2023
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 566
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Tidskriftsartikel (refereegranskat)abstract
- The electrical conductivities of the dilute solutions containing ionic liquids (1-hexyl-3-methylimidazolium chloride [Hmim]Cl, 1-hexyl-3-methylimidazolium bromide [Hmim]Br, and 1-hexyl-3-methylimidazolium iodide [Hmim]I) with water and isopropanol were determined in the temperature ranging from 293.15 to 313.15 K. The liquid densities of all binary mixtures were further determined for model parameterization. In theoretical modeling, the limiting molar conductivities Λ0(T) were first obtained using the Debye-Hückel-Onsager (DHO) equation, and thereafter the ion association constants KA(T) were determined using the Shedlovsky equation. The effects of temperature, dielectric constant, and anion size on the values of Λ0(T) and KA(T) were systematically discussed. The Eyring activation enthalpy of charge transport ∆H* and the Walden values Λ0η for all studied binary mixtures were obtained from the temperature-dependent Λ0(T).
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| 6. |
- Li, Jiahui, et al.
(författare)
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Extra low friction coefficient caused by the formation of a solid-like layer : A new lubrication mechanism found through molecular simulation of the lubrication of MoS2 nanoslits
- 2018
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier. - 1004-9541 .- 2210-321X. ; 26:12, s. 2412-2419
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Tidskriftsartikel (refereegranskat)abstract
- Monolayer molybdenum disulfide (MoS2) is a novel two-dimensional material that exhibits potential application in lubrication technology. In this work, molecular dynamics was used to investigate the lubrication behaviour of different polar fluid molecules (i.e., water, methanol and decane) confined in monolayer MoS2 nanoslits. The pore width effect (i.e., 1.2, 1.6 and 2.0 nm) was also evaluated. Results revealed that decane molecules exhibited good lubricating performance compared to the other two kinds of molecules. The friction coefficient followed the order of decane < methanol < water, and decreased evidently as the slit width increased, except for decane. Analysis of the spatial distribution and mobility of different confined fluid molecules showed that a solid-like layer was formed near the slit wall. This phenomenon led to the extra low friction coefficient of confined decane molecules
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| 7. |
- Bao, Ningzhong, et al.
(författare)
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Thermodynamic modeling and experimental verification for ion-exchange synthesis of K2O·6TiO2 and TiO2 fibers from K2O·4TiO2
- 2002
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Ingår i: Fluid Phase Equilibria. - 0378-3812 .- 1879-0224. ; 193, s. 229-243
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Tidskriftsartikel (refereegranskat)abstract
- A thermodynamic model was established to determine ion-exchange conditions for the synthesis of potassium hexatitanate (K2O·6TiO2) and titanium dioxide (TiO2) from potassium tetratitanate (K2O·4TiO2) fiber. In the proposed model equilibrium species in the solid phase and corresponding ion-exchange equilibrium constants at 298.15 K were determined from the experimental data of Sasaki et al. [Inorg. Chem. 24 (1985) 2265]. In order to verify the proposed model, prediction results were compared with experimental data determined in literature and those measured in this work. The comparison shows a good agreement. Based on this, the proposed model was also used to predict more extensive suitable conditions for the synthesis of K2O·6TiO2 and TiO2.
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| 8. |
- Cao, Danyang, et al.
(författare)
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Biolubricant
- 2023
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Ingår i: Sustainable Production Innovations. - : John Wiley & Sons. ; , s. 1-56
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Cao, Jian, et al.
(författare)
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Heterogeneous consecutive reaction kinetics of direct oxidation of H2 to H2O2: Effect and regulation of confined mass transfer
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 455
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Tidskriftsartikel (refereegranskat)abstract
- Porous catalysts in heterogeneous reactions have played an important role in the modern chemical industry, but it is still challenging to quantitatively describe mass transfer and surface reaction behaviors of reactants in nano-confined space. Direct synthesis of hydrogen peroxide (H2O2) is considered as an attractive alternative to anthraquinone oxidation process, while the confined mass transfer of H2O2 in porous catalysts limits the reactivity. In this work, taking the consecutive reaction of H2O2 synthesis as an example, a quantitative method in modeling the effects of confined mass transfer on the reactivity was studied. More specifically, calorimetry was developed to characterize the confined structures of porous carbon experimentally, the linear nonequilibrium thermodynamics and the statistical mechanics method were further combined. Then, the heterogeneous consecutive reaction kinetics and the Thiele modulus influenced by confined mass transfer were modeled. Consequently, regulation strategies were proposed with the help of theoretical models. The optimized catalyst with biological skeleton carbon support and 0.5 wt% palladium loading shows an excellent catalytic performance. Lastly, for the mesoscience in heterogeneous reaction, the resistance was explored as a quantitative descriptor to compromise in the competition between mass transfer and surface reaction. The mesoscale structures were considered as the dynamic spatiotemporal distribution of substance concentrations, and the resistance minimization multi-scale (RMMS) model was proposed.
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| 10. |
- Chen, Jingjing, et al.
(författare)
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A high efficient heat exchanger with twisted geometries for biogas process with manure slurry
- 2020
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Heat-transfer enhancement in manure slurry is crucial for increasing the efficiency and production of biogas during anaerobic digestion in biogas plants. In this study, a novel heat exchanger with an optimal twisted geometry was developed based on the numerical screening of the twisted tubes with equilateral polygons, and experiments were conducted to validate the numerical results. It was observed that the SST k-ω model is more efficient than other turbulence models in representing the heat transfer performance of the twisted tubes, and the numerical model with a thermostatic wall can be used to reliably screen the twisted geometries. The twisted hexagonal tube has the optimal geometry, with enhancement capability of up to 1.4 times compared to that of the circular tube. The formation of high continuity regions with relatively strong heat-transfer rates along the heat-exchange wall is the main reason for the high performance during heat transfer. The external heating process was integrated in a full-scale biogas plant, and the model and algorithm were developed and validated with additional experiments to describe the overall performance of both conventional and screened optimal geometries under different conditions. It was observed that a profit equivalent to 39% of total production for a large-scale biogas plant can be achieved owing to energy conservation in external heating with the twisted hexagonal tubes.
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