查看更多>>摘要：Hybrid extraction-distillation process has shown its strength in energy saving over pure distillation process; however, the widely used sequential iterative optimization method and the ignorance of optimizing distillation column operating pressure would miss a better optimal design. In this work, a rigorous pseudo-transient (PT) tray model and a steady-state optimization algorithm assisted by PT model were applied to realize the simultaneous optimization of column structural parameters and operating conditions. Two case studies were optimized to validate the correctness and the effectiveness of the proposed method. The optimal results revealed that it is more economically favorable to treat design specifications of product purity as inequality constraints to expand the search space of optimization. In the water/PM separation case study, the optimal operating pressures that facilitate separation in strippers help reduce the TAC by 14.64%, thanks to smaller reboiler duties per unit feed and smaller circulating stream flow rates. In addition, a heat integration design is feasible which reduces the TAC by 35.43%. This case study emphasizes the importance of optimizing operating pressures for such type of process.
Joana M.B. DomingosGonzalo A. MartinezElena Morselli
10页
查看更多>>摘要：The application of reverse osmosis (RO) and nanofiltration (NF) to concentrate and/or fractionate volatile fatty acids (VFAs, occurring in acidogenic effluents) was systematically assessed for the first time using three commercial spiral wound modules. A bench scale plant was used to test the polyamide membrane cartridges, namely: AG1812-34D, DK1812-34D and NFS-3B-1812F. The effects of main operational parameters (pH, temperature, applied pressure) were firstly studied in total recirculation mode, using different total and relative VFA compositions. Thereafter, batch concentration tests were carried out (at constant applied pressure, ca. 30 bar) to fully characterize the RO and NF modules. AG1812-34D performed as an RO module and it allowed concentrating target solutions almost 3 times without relevant VFA losses (<4%) in the permeate side. All tested parameters were observed to affect concentration performances. However, typical pH levels occurring in acidogenic effluents allowed to achieve fully satisfactory VFA rejections. DK1812-34D and NFS-3B-1812F performed as NF modules and could represent suitable solutions for VFA fractionation. Separation factors significantly increased by pH rise; in particular, high acetic and propionic acid separation factors over butyric acid were achieved at pH 9, with DK1812-34D module.
查看更多>>摘要：H2 production processes from steam methane reforming and combined cycle power plants require carbon dioxide removal from raw synthesis gas to obtain a useful H2-rich product stream. In this work, a wide variety of operating configurations were techno-economically evaluated in Aspen Plus commercial process simulator to improve the efficiency and costs of the pre-combustion CO2 capture process based on chemical absorption using [P_(2228)][CNPyr] ionic liquid. Multiple absorption (from 30 °C to 70 °C) and regeneration (between 90 °C and 120 °C) temperatures were tested along with four different regenerating pressures: 0.1, 0.25, 0.5 and 1 bar. Energy and solvent consumptions and capital and operating costs were calculated for nine configurations using the COSMO-based/Aspen methodology combined with Aspen Economic Analyzer tool. The most promising results were obtained when regenerating the IL at 1 bar and at elevated absorption and regeneration temperatures, due to the higher operating and equipment costs associated with vacuum and the greater utilities cost related to heat transfer when the gap between both temperatures grows. The minimum cost achieved was 64.1$/t_(CO2) considering an IL scaled up price of 50 $/kg, but it could even be further less than 40 S/t_(CO2) goal for new generation solvents, when only direct costs were considered.
查看更多>>摘要：Various photocatalyst powders (such as bismuth oxide/bismuth oxyiodide) can remove contaminants and microorganism from waterbody efficiently, but their practical application was limited due to poor recovery performance. To address this problem, we reported the construction of epoxy resin induced hydrothermal in-situ growth Z-scheme bismuth oxide/bismuth oxyiodide heterostructure film on various metals as a recycled photocatalysts. Novel epoxy resin was proposed to substitute in-situ growth film of seed layer constructed by magnetron sputtering and electro deposition between film and metals. The universal flower-like microspheres (diameter: 3-5 μm) bismuth oxide/bismuth oxyiodide films (thickness: 13 μm) were grown on various metals. Additional film decorated by photothermal catalyst nanoparticles (such as Ag, diameter: 200 nm) was constructed. The metal/epoxy resin/film can efficiently photodegrade 83.8% of Rhodamine B (RhB) and 73.2% of triclosan (TCS) within 210 min under the visible light illumination. Furthermore, antimicrobial efficiency of bismuth oxide/bismuth oxyiodide neglected in the reported study was assessed and exhibited inactivation of >99.99% Escherichia coli(E. coli) and Staphylococcus aureus (S. aureus) at 6 h and 9 h of irradiation. The Z-scheme heterostructure film can simultaneously produce ·O2~ and ·OH. In addition, there was a synergistic effect between the film and the silver nanoparticles, silver nanoparticles can not only further enhance the separation efficiency of photocarriers and generation efficiency of free radical, but also form silver ions to further improve the antimicrobial property. Therefore, metal/epoxy resin/film had broad application prospects as an easily recycled photocatalyst and can also be adopted to prepare other films for photocatalytic application.
查看更多>>摘要：Stabilizing SrFeO_(3-δ) in cubic structure is of great significance for its application in solid oxide fuel cells. Herein, a rational way is reported to tune the structure and performance of SrFeO_(3-δ) perovskite as oxygen reduction electrodes by embedding aluminum cation in B-site. Compared with their parent oxide, the obtained stabilized cubic perovskites SrFe_(1-x)AlxO_(3-δ) (x = 0.1 and 0.2) show much improved electro catalytic activity, achieving area specific resistance values of 0.57, 0.15 and 0.34 Ωcm~2 at 700 °C in air for SrFeO_(3-δ), SrFe_(0.9)Al_(0.1)O_(3-δ) and SrFe_(0.8)Al_(0.2)O_(3-δ), respectively. Such improved performance is a result of the exceeding 2-fold increase in oxygen chemical bulk diffusion and surface exchange kinetics due to Al~(3+) doping. Moreover, favorable CO2-resistance is also demonstrated. DFT calculations are carried out to reveal the accelerated oxygen reduction reaction and enhanced CO2 tolerance. This work indicates an aluminum dopant in B-site may provide a highly attractive strategy for the future development of cathode materials.
查看更多>>摘要：Endowed with high energy efficiency and low emission, protonic ceramic fuel cells (PCFCs) are emerging as sustainable energy converters at intermediate temperatures. However, the sluggish kinetics of proton involved oxygen reduction reaction (P-ORR) severely limits the commercial application of PCFCs. Herein, we highlight a novel anion defect engineered PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5.84-δ)F_(0.16) (16F-PBSCF) perovskite oxyfluoride as a potential single-phase cathode towards PCFCs. It is revealed that F incorporation not only improves oxygen reduction kinetics but also accelerates water incorporation kinetics, ultimately resulting in high electro catalytic performance. As a proof of concept, the PCFCs with 16F-PBSCF cathode delivers a high peak power density of 0.51 W cm~(-2) at 600 °C, superior to the PCFCs using pristine PBSCF cathode. These findings disclose that tailoring anion defect in perovskite oxyfluorides is a feasible approach to boost the P-ORR of cathode materials for PCFCs.
查看更多>>摘要：The separation and capture of Br~- ions from aqueous solutions is of great significance in view of their dual characteristics, that is, its economic value and its harmful effect on human body. In this study, BiOBr@PPy electroactive hybrid film with core-shell structure, which was fabricated by in-situ coating conductive PPy on BiOBr with ion storage space, was applied to selectively capture Br~- ions using electronically switched ion exchange technology (ESIX). The capture capacity of BiOBr@PPy hybrid film reached 146.2 mg g~(-1) at 0.8 V oxidation voltage. While, the hybrid film had an excellent selectivity towards Br~- ions in the aqueous solution with several competing anions. It was confirmed that selective Br~- ion capture/release by the BiOBr@PPy hybrid film was achieved through the synergistic effect generated from sufficient Br~- ions storage space of BiOBr, highly conductivity and ion screening function of PPy, and powerful driving forces jointly activated by the electrochemical redox reaction of BiOBr and PPy. In addition, the capacity retention efficiency and release rate of the hybrid film still remained above 80% after 10 cycles due to the strategy of in-situ coating of PPy. It is predicted that such a BiOBr@PPy hybrid film with synergistic effects may be a potential electroactive material for the separation and capture of Br~- ions from aqueous solutions.
查看更多>>摘要：Conventional colloid filtration theory (CFT) uses the single collector contact efficiency (η) to describe the mass transfer of colloids to a collector surface. However, this approach neglects the full complexity of the pore structure and flow field of real porous media. In this study, the porous medium geometry, flow field, and colloid mass transfer are quantified using a pore-network model (PNM). A database of pore scale η is established by finite-element method to train a Neural-network model (NNM). The reasonable prediction of η indicates the potential of using the developed KNMs as an alternative to correlation equations, which can free the users from repeated numerical simulation. In contrast to the prediction by conventional CFT, the value of η in the PNM occurs as a distribution, which is dependent upon the geometry parameters of the PNM. The mean value of η increases with the standard deviation of pore radius and decreases with the curvature number, but the dependency on coordination number is more complex. Upscaled values of the deposition rate coefficient (kd) corresponding to the distribution of η are calculated by the breakthrough curves by PNMs. The prediction of kd by PNM is then compared with that by CFT. Results show that kd predicted by PNM shows more significant response to velocity change, and less remarkable response to colloid density change than kd predicted by CFT. The comparison between the flow velocity distribution between PNM and CFT shows that the high-velocity region of the flow field in the porous media has been neglected in CFT, which can lead to insufficient consideration of convection. The results of this work imply that it is necessary to consider the influence of the complex pore structure of porous media on the collection of colloids.
查看更多>>摘要：The special bioinspired structure will help membranes to improve the antifouling properties during the membrane distillation (MD) process. Here, a new MD utilized membrane with oriented shish-kebab structure was prepared by stirring the ultrahigh molecular weight polyethylene (UHMWPE)/decalin solution to induce the shish-kebab crystals to grow on a polyester mesh along the flow field, and then coated with fluororesin to decrease the surface energy. The multi-stage extraction drying technology was adopted to reduce the membrane shrinkage in the dry process and make the shish-kebab membranes have high porosity (77.5%). More interesting, when the water flows along the shish direction, just like the fish gill works, the membrane has better resistance to NaCl, CaCO3 scaling, due to the nanoscale structure can intensify the interfacial nanoscale turbulent flow and hinder the crystal deposition. Specifically, the membrane has a high-water recovery of 92.5% and a low conductivity increase (from 2.76 to 8.33 μS/cm in 70 h) in the long-term MD process.
查看更多>>摘要：In this study, the usage of dual hybrid organosilica is proposed for discussing the influence of thermal-driven chain stitching on the organosilica membrane structure for the first time. The influence of the gas thermal diffusivity on the hybrid organosilica membrane for separating H2 from CH4, C2H6, and C3H8, is discussed in detail. The characterization and permeation tests revealed that the optimal condition of the organosilica membrane fabrication is the usage of nitrogen as calcination atmosphere owing to the mild reaction. In addition, it is found that when N2 is used as the calcining gas and calcination is performed at a lower temperature, it is beneficial for the separation of small-molecule gases. However, calcination at higher temperatures is beneficial to the separation of gas pairs with a big difference in kinetic diameter. The as-prepared M-N2-300 exhibited the maximum selectivity of 37.32 for CO2/N2, 82.37 for CO2/CH4, 47.51 for Ha/N4, and 109.28 for H2/CH4, and ideal H2 permeance of 2.24 × 10~(-8) mol/(m~2sPa). Moreover, the as-prepared M-N2-500 exhibited the maximum selectivity for the following gases: 438.99 and 301.47 toward H2/C2H5 and H2/C3H8, respectively, at the ambient environment, and satisfactory H2 permeance of 5.14 × 10~(-8) mol/(m~2sPa). This shows the potential and industrial relevance for gas-separation concerning applications like H2 energy production and olefins/paraffins recovery.
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