| 1. |
- Ma, Chunyan, et al.
(författare)
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CO2 Separation by a Series of Aqueous Morpholinium-Based Ionic Liquids with Acetate Anions
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 8:1, s. 415-426
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Tidskriftsartikel (refereegranskat)abstract
- In this work, CO2 absorption capacities in a series of aqueous N-alkyl-N-methylmorpholinium-based ILs with acetate as the counterpart anion were investigated. Among these ILs, N-butyl-N-methylmorpholinium acetate ([Bmmorp][OAc]) with the highest CO2 absorption capacity was screened for thermodynamic modeling. The non-random two-liquid model and the Redlich–Kwong equation of state (NRTL-RK model) were used to describe the phase equilibria. The CH4 absorption capacity in the aqueous [Bmmorp][OAc] was also measured in order to verify the results predicted from the thermodynamic modeling, and the comparison shows the reliability of the model prediction. The parameters were embedded into the commercial software Aspen Plus. After that, the aqueous [Bmmorp][OAc] solutions with 30–40 wt % of water were selected to carry out process simulation for CO2 separation from biogas, and it was found that using these aqueous [Bmmorp][OAc] gave rise to lower energy usage and smaller size of equipment than other physical solvents. The results suggest that aqueous [Bmmorp][OAc] solution can be used as an alternative to organic solvents and has the potential to decrease the cost of CO2 separation.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- Li, Fangfang, et al.
(författare)
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Combination of CO2 electrochemical reduction and biomass gasification for producing methanol : A techno-economic assessment
- 2024
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Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 307
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Tidskriftsartikel (refereegranskat)abstract
- Combining CO2 electrochemical reduction (CO2R) and biomass gasification for producing methanol (CH3OH) is a promising option to increase the carbon efficiency, reduce total production cost (TPC), and realize the utilization of byproducts of CO2R system, but its viability has not been studied. In this work, systematic techno-economic assessments for the processes that combined CO2R to produce CO/syngas/CH3OH with biomass gasification were conducted and compared to stand-alone biomass gasification and CO2R processes, to identify the benefits and analyze the commercialization potential of different pathways under current and future conditions. The results demonstrated that the process that combined biomass gasification with CO2R to CO represents a viable pathway with a competitive TPC of 0.39 €/kg-CH3OH under the current condition. For all the combined cases, electricity usage for CO2R accounts for 36–76% of total operating cost, which plays a key role for TPC. Sensitivity analysis confirmed that the process that combined biomass gasification with CO2R to CO is sensitive to the price of electricity, while both CO2R performance and prices of stack and electricity are important for the processes that combined with CO2R to syngas/CH3OH.
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| 5. |
- Li, Hailong, 1976-, et al.
(författare)
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A new modification on RK EOS for gaseous CO2 and gaseous mixtures of CO2 and H2O
- 2006
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 30:3, s. 135-148
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Tidskriftsartikel (refereegranskat)abstract
- To develop an equation of state with simple structure and reasonable accuracy for engineering application, Redlich-Kwong equation of state was modified for gaseous CO2 and CO2-H2O mixtures. In the new modification, parameter 'a' of gaseous CO2 was regressed as a function of temperature and pressure from recent reliable experimental data in the range: 220-750 K and 0.1-400 MPa. Moreover, a new mixing rule was proposed for gaseous CO2-H2O mixtures. To verify the accuracy of the new modification, densities were calculated and compared with experimental data. The average error is 1.68% for gaseous CO2 and 0.93% for gaseous mixtures of CO2 and H2O, Other thermodynamic properties, such as enthalpy and heat capacities of CO2 and excess enthalpy of gaseous CO2-H2O mixtures, were also calculated; results fit experimental data well, except for the critical region.
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| 6. |
- 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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| 7. |
- 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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| 8. |
- Ma, Chunyan, et al.
(författare)
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Development of Low-Cost Deep Eutectic Solvents for CO2 Capture
- 2017
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 142, s. 3320-3325, s. 3320-3325
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Tidskriftsartikel (refereegranskat)abstract
- CO2 capture plays an important role to mitigate CO2 emissions. Deep eutectic solvents (DESs) as promising absorbents for CO2 separation have raised lots of attention. As a new class of ionic liquids (ILs), DESs maintain most of the favorite properties of ILs but avoid their economic and environmental problems. However, the viscosity of the synthesized DESs is relatively high, resulting in slow mass transfer rate (or slow sorption kinetics) and then may lead to a large equipment-size. The CO2 solubility in the DESs still needs to be improved. In our work, 35 DESs were prepared and screened in terms of their CO2 solubility and viscosity. Among them, 15 DESs with high CO2 solubility and low viscosity compared to the conventional ILs were chosen as the promising candidates. In addition, the effect of water as a co-solvent for the glycerol-based DES with relatively high viscosity was investigated, and two other DESs that demonstrated relatively high sorption capacity and low viscosity were chosen for functionalization to further improve their CO2 sorption capacity. The results showed that the viscosity decreased drastically from 716 to 20 mPa·s, while the CO2 solubility increased from 0.26 to 0.33 mol/kg DES by the addition of a small amount of water into the glycerol-based DES (BTMA/GLY (1:2)). The further increase of the amount of H2O decreased the CO2 solubility due to the low CO2 solubility in H2O. In addition, after functionalization of TPAC/ EA(1:4), the CO2 solubility increased from 1.4 to 3.2 mol/kg DES, which showed a better performance compared with the common ILs.
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| 9. |
- Nookuea, Worrada
(författare)
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Impacts of Thermo-Physical Properties on Chemical Absorption for CO2 Capture
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Following the climate change mitigation target in Paris agreement, the global warming has to be limited to 2.0°C above the preindustrial levels. One of the potential methods is carbon capture and storage (CCS), which can significantly reduce the CO2 emissions from the vast point sources such as power plants, industries, and natural gas processes. The CCS covers four steps which are capture, conditioning, transport, and storage. For the capture part, post-combustion capture is easier to implement based on today’s technologies and infrastructure compared with pre-combustion and oxy-fuel combustion captures, since the radical changes in the structure of the existing plant are not required.To design and operate different CCS processes, the knowledge of thermo-physical properties of the CO2 mixtures is of importance. In this thesis, the status and progress of the studies related to the impacts of the uncertainty in thermo-physical properties on the design and operation of the CCS processes were reviewed. The knowledge gaps and the priority of property model development were identified.According to the identified knowledge gaps in the review, the impacts of thermo-physical properties which are the density, viscosity, and diffusivity of the gas and liquid phases, and the surface tension and heat capacity of the liquid phase on the design of the absorber column for the chemical absorption using aqueous monoethanolamine were quantitatively analyzed. An in-house rate-based absorption model was developed in MATLAB to simulate the absorption process, and the sensitivity study was done for each property. An economic evaluation was also performed to further estimate the impacts of the properties on the capital cost of the absorption unit. For column diameter of the absorber, the gas phase density shows the most significant impacts; while, the liquid phase density and viscosity show the most significant impacts on the design of the packing height and also the capital cost of the absorption unit. Therefore, developing the flue gas density model and liquid phase density and viscosity models of the aqueous solvents with CO2 loading should be prioritized.
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| 10. |
- Zhang, Zhibo, et al.
(författare)
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Novel artificial ionic cofactors for efficient electro-enzymatic conversion of CO2 to formic acid
- 2022
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Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- The low yield of enzymatic conversion of CO2 to formic acid as well as the high cost and instability of using the natural cofactor (NADH) hamper the large-scale application of the CO2 enzymatic utilization. To address these issues and to improve the production of formic acid, six bipyridinium-based artificial cofactors were developed for the enzymatic conversion of CO2 and further integrated with the electrocatalytic regeneration of the cofactors for the formic acid production. All of them did show a higher catalytic performance compared to NADH. Particularly, 1,1′-bis(2-(dimethylamino)ethyl)-4,4′-bipyridinium bromine did exhibit the highest catalytic performance with a high formic acid concentration of 4.76 mM in 60 min, which is 47 times higher than that of the natural cofactor NADH and is also currently the highest performance among the reported artificial cofactors in literature. Thermodynamic analysis, electrochemical investigations, and molecular dynamics simulations were performed to clarify the structure-energy relationship of the functional bipyridinium-based salts and to rationalize how it is affected by the different functional groups. This study gives a deep insight into the role of artificial cofactors in enzymatic reactions and can clearly promote the development of novel bioelectrochemical conversion of CO2.
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