This study first develops a facile method to synthesize zeolitic imidazolate framework cuboid (ZIF-C) nanosheets with tunable thickness from 70 to 170 nm from aqueous polymer solutions. The obtained ...ZIF-C nanosheets were characterized by various techniques, including X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), N2 adsorption and thermogravimetric analysis (TGA), to understand their compositional and structural properties. The synthesized ZIF-Cs nanosheets with different thicknesses were further applied as nanofillers to prepare Pebax-based mixed matrix membranes (MMMs) to study the effect of the morphology on membrane properties and CO2/N2 separation performances under different relative humidity (RH) conditions. Results reveal that the incorporation of these ZIF-Cs simultaneously enhances CO2 permeability and CO2/N2 selectivity in the mixed matrix membranes. In addition, MMMs with the thickest ZIF-C nanosheet present better performance. A CO2 permeability of 387.2 Barrer accompanied with a CO2/N2 selectivity of 47.1 has been documented, nearly doubled in CO2 permeability with slightly increased selectivity compared with membranes containing thinner nanosheets.
In this work, defect-free thin-film-composite (TFC) hollow fiber membranes containing various amino acid salts as CO2 facilitated transport carriers were fabricated via dip-coating. Four different ...amino acid salts, i.e., potassium prolinate (ProK), potassium argininate (ArgK), potassium glycinate (GlyK) and potassium cysteinate (CysK), were selected and embedded within polyvinyl alcohol (PVA) matrix. TGA, FTIR, SEM and humid mixed gas permeation test were used for the evaluation. Experiments show that adding amino acid salts into the PVA matrix significantly increases the CO2 permeance with little influence on the CO2/N2 selectivity. ProK was found the most effective within the four investigated mobile carriers; The addition of 40% ProK into the PVA matrix nearly doubled the CO2 permeance (from 399 to 791 GPU). The PVA/amino acid salt membranes also exhibited good long-term stability, in which both CO2 permeance and CO2/N2 selectivity remained nearly unchanged in a 20-h test and after a two-week shutdown period.
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•Four amino acid salts were used as mobile carriers in PVA-based membranes to enhance CO2 transport.•Defect-free TFC hollow fiber membranes with selective layer thicknesses of <500 nm were fabricated.•Lab-size hollow fiber membrane module was prepared and tested using humid mixed feed gas.•Adding amino acid salt improves the CO2 permeance significantly without sacrificing the selectivity.•The membranes show good long-term stability in the test and after a shutdown operation.
The development of multilayer composite membranes for CO2 separation has gained increasing attention due to the desire for energy efficient technologies. Multilayer composite membranes have many ...advantages, including the possibility to optimize membrane materials independently by layers according to their different functions and to reduce the overall transport resistance by using ultrathin selective layers, and less limitations on the material mechanical properties and processability. A comprehensive review is required to capture details of the progresses that have already been achieved in developing multilayer composite membranes with improved CO2 separation performance in the past 15–20 years. In this review, various composite membrane preparation methods were compared, advances in composite membranes for CO2/CH4 separation, CO2/N2 and CO2/H2 separation were summarized with detailed data, and challenges facing for the CO2 separation using composite membranes, such as aging, plasticization and long-term stability, were discussed. Finally the perspectives and future research directions for composite membranes were presented.
Data mining technology has been applied in many fields. Prototype-based cluster analysis is an important data mining method, but its ability to discover knowledge is limited because of the need to ...know the number of target data categories and cluster prototypes in advance. Artificial immune evolutionary network clustering is a clustering method based on network structure. Compared with prototype-based cluster analysis, it has the advantage of realizing unsupervised learning and clustering without any prior knowledge of data. However, artificial immune evolutionary network clustering also has problems such as a lack of guidance in the clustering process, fuzzy boundary sensitivity, and difficulty in determining parameters. To solve these problems, an artificial immune network clustering algorithm based on a cultural algorithm is proposed. First, three kinds of knowledge are constructed: normative knowledge is used to regulate the spatial range of population initialization to avoid blindness; state knowledge is used to distinguish the type of antigen, and immune defense measures are taken to prevent the network structure caused by noise and boundaries from being unclear; and topology knowledge is used to guide the antigen for optimal antibody search. Second, topology knowledge in the cultural algorithm is used to characterize the distribution of antigens and antibodies in space, and elite learning is used to improve the traditional clone mutation operator. Based on the shadow set theory, a method for adaptively determining the compression threshold is proposed. Finally, the results of simulation experiments show that the proposed algorithm can effectively overcome the above problems, and the clustering performances on a synthetic dataset and an actual dataset are satisfactory.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•A pre-pilot scale amino acid salts based facilitated transport HF membrane was fabricated.•The membrane module was tested for CO2 capture from the real stream flue gas with impurities.•Gas ...separation test was carried out in the temperature range of 80–115 °C.•The effects of process operation parameters on the membrane separation performances were investigated.•The membrane stability in the real separation conditions was studied from a one-week test.
In this work, a pre-pilot scale hollow fiber membrane module with a PVA/ProK hybrid membrane containing up to 40 wt% amino acid salt was fabricated and tested infield for CO2 capture. The petroleum coke-fired flue gas generated from the rotary kiln provided with a 5-stage cyclone pre-heater tower for the production of grey clinker in the Colacem cement plant in Gubbio (PG), Italy, was used as feed gas after a simple filtration to remove the suspended particulate matter without further pretreatment. The temperature for the membrane test was ranging from 80 to 115 °C. The effects of various parameters including operation temperature, pressure, sweep gas flow rate, vacuum grade, and the impurities in the feed were systematically investigated. Under optimized condition, CO2 content of 50% in the permeate and CO2 permeate flux of ˜5 × 10−3 cm3(STP) cm−2 s−1 were documented, which is comparable with other facilitated transport membranes. The presence of impurities in the feed stream showed a negligible effect on the CO2 separation performance. Long-term stability was also studied through a test for a duration of 1 week at 90 °C.
This work presents the development of molecular-based mathematical model for the prediction of CO2 solubility in deep eutectic solvents (DESs). First, a comprehensive database containing 1011 CO2 ...solubility data in various DESs at different temperatures and pressures is established, and the COSMO-RS-derived descriptors of involved hydrogen bond acceptors and hydrogen bond donors of DESs are calculated. Afterwards, the efficiency of the input variables, i.e., temperature, pressure, COSMO-RS-derived descriptors of HBA and HBD as well as their molar ratio, is explored by a qualitative analysis of CO2 solubility in DESs using a simple multiple linear regression model. A machine learning method namely random forest is then employed to develop more accurate nonlinear quantitative structure-property relationship (QSPR) model. Combining the QSPR validation and comparisons with literature-reported models (i.e., COSMO-RS model, traditional thermodynamic models and equations of state methods), the developed QSPR model with COSMO-RS-derived parameters as molecular descriptors is suggested to be able to give reliable predictions of CO2 solubility in DESs and could be used as a useful tool in selecting DESs for CO2 capture processes.
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•A QSPR model is developed for predicting CO2 solubility in DESs.•Efficiency of the input variables is explored by a multiple linear regression model.•Importance of the input variables in the QSPR model is ranked by random forest model.•CO2 solubility predictions by QSPR model are compared to the COSMO-RS model.•QSPR model is suggested to be a reliable tool for selecting DESs for CO2 capture.
CO2 separation performance in facilitated transport membranes has been reported depended not only on the CO2 carrier properties but also to a great extent on the polymeric matrix regarding the ...capacity of retaining water and carriers as well as the processability for coating defect-free ultra-thin films. In this study, the blends of hydrophilic polymers polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were studied to find an optimal polymer matrix to host carriers in facilitated transport membranes for enhanced CO2 separation. It is found out that the optimized blend is 50/50 PVA/PVP by weight, which shows a significant increase in the water uptake (from 63 to 84%) at equilibrium state compared to the neat PVA. Polyethyleneimine (PEI) was employed to provide sample carriers to evaluate the synergistic effect of PVA and PVP on the CO2 separation performance. A thin film composite (TFC) membrane of the optimized blend (50/50 PVA/PVP with 50 wt% PEI) was fabricated on polysulfone (PSf) porous support. The fabrication of the TFC membranes is simple and low cost, and CO2 permeance of the optimized blend membrane is nearly doubled with the CO2/N2 selectivity remained unchanged, showing great potential for industrial applications of the resulted membranes.
A polymeric matrix suitable to host CO2 facilitated transport carriers was optimized by blending PVA and PVP. The water-retention of the blend membrane and the processability for thin-film coating were improved, showing synergetic enhancement on CO2 separation permeance. Display omitted
In order to design ionic liquids as absorbents for gas separation, a systematic computer-aided ionic liquid design (CAILD) methodology is applied and demonstrated by three cases of CO2 capture. ...Mixed-integer nonlinear programming problems are formulated, where a mass-based Absorption-Selectivity-Desorption index (ASDI) integrating the most important thermodynamic properties of ILs (i.e., gas solubility, selectivity, and desorption capacity) is proposed as the objective function and calculated by the COSMO-GC-IL inputted COSMO-SAC model. The physical properties of ionic liquids are implemented as optimization constraints, which are estimated by semiempirical models. The reliability of the thermodynamic method for IL-gas systems is validated first by comparing a large number of experimental and calculated data of Henry’s law constant of different gases in ILs. Then, comparative CAILD studies are performed for CO2 separation from flue gas (CO2/N2) to demonstrate the importance of ASDI for identifying practically attractive ILs. Afterward, the developed method is applied to design IL solvents for the separation of CO2 from syngas (CO2/H2) and sour gas (CO2/H2S). The correspondingly designed ILs for each case (OAc− and COOH-functionalized pyridinium for CO2/H2 and CO2/N2; AlCl4− and long branched alkyl substituted pyridinium for CO2/H2S) are analyzed from the σ-profile point of view.
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