This study develops a quantitative structure-property relationship (QSPR) model using a hybrid neural network and particle swarm optimization (PSO) to predict the gas separation performance of 120 polymers of intrinsic microporosity (PIMs). Over 5000 descriptors, including topological, constitutional, functional groups, and geometrical properties, were computed using alvaDesc software. Genetic algorithm optimization combined with partial least squares regression was used to select relevant descriptors for predicting PIM permeability to N2, CH4, and CO2. A hybrid neural network model with particle swarm optimization-based backpropagation (PSO-BP) algorithms was used for permeability prediction, and the results were compared to experimental published data. The PSO-BP model showed promising results, with root mean squared error (RMSE) values of 0.0048, 0.000743, and 0.0045 for CO2, N2, and CH4, permeabilities respectively. Key descriptors for predicting PIM permeability are associated with multiple physicochemical properties, including GATS, 3D Morse, TDB, SpMax, MATS, CATS3D, RDF, and ATS descriptors. CO2 permeability prediction requires more 3D descriptors than N2 and CH4.

Membrane separation has emerged as a promising alternative to conventional separation processes for CO2 capture. In this study, a new copolymer architecture corresponding to a PEO-based grafted multiblock copolymer (PUI-g-PEDEGA1000) was compared to the corresponding nongrafted multiblock copolymer (PUI-g) for elaborating mixed matrix membranes with high loadings of metal organic framework ZIF-8. The new grafted multiblock copolymer architecture greatly improved the ZIF-8 dispersion and the ZIF-8/polymer interactions. The gas permeation properties were assessed by time-lag experiments for pure gases CO2 and N2 at 2 bar and 35 degrees C. For the highest ZIF-8 loading (40% vol), the new copolymer architecture led to the best CO2 permeability (112 Barrer), corresponding to an improvement by a factor of 6 compared to the unloaded membrane, while the ideal selectivity alphaCO2/N2 was maintained at a relatively high level (30.4). Finally, the CO2/N2 permeability experimental results were compared with permeation data calculated from semipredictive ideal permeability models.

Herein, experimental and theoretical approaches were used to design a new composite membrane for desalination by pervaporation. The theoretical approaches demonstrate the possibility to reach high mass transfer coefficients quite close to those obtained with conventional porous membranes if two conditions are verified: (i) a dense layer with a low thickness and (ii) a support with a high-water permeability. For this purpose, several membranes with a cellulose triacetate (CTA) polymer were prepared and compared with a hydrophobic membrane prepared in a previous study. The composite membranes were tested for several feed conditions, i.e., pure water, brine and saline water containing a surfactant. The results show that, whatever the tested feed, no wetting occurred during several hours of desalination tests. In addition, a steady flux was obtained together with a very high salt rejection (close to 100%) for the CTA membranes. Lastly, the CTA composite membrane was tested with real seawater without any pretreatment. It was shown that the salt rejection was still very high (close to 99.5%) and that no wetting could be detected for several hours. This investigation opens a new direction to prepare specific and sustainable membranes for desalination by pervaporation.

The current study presents for the first time the synthesis of a new 2:1-[α/aza]-pseudopeptide series possessing charged amino acids (i.e., lysine) and aims at studying the influences of chirality, backbone length, and the nature of the lysine side chains on the conformation of the 2:1-[α/aza]-oligomers in solution using NMR, FTIR spectroscopy and molecular dynamic calculations. The spectroscopic results emphasized the conservation of the β-turn conformation adopted by the trimers regardless of the chirality which demonstrated a noticeable effect on the conformation of homochiral hexamer (8c) compared with the hetero-analogue (8d). The molecular dynamic calculations predicted that the chirality and the side chain of the lysine residues caused a little distortion from the classical β-turn conformation in the case of short trimer sequences (7c and 7d), while the chirality and the backbone length exerted more distortion on the β-turn adopted by the longer hexamer sequences (8c and 8d). The large disturbance in hexamers from classical β-turn was attributed to increasing the flexibility and the possibility of molecules to adopt a more energetically favorable conformation stabilized by non-classical β-turn intramolecular hydrogen bonds. Thus, alternating d- and l-lysine amino acids in the 2:1-[α/aza]-hexamer (8d) decreases the high steric hindrance between the lysine side chains, as in the homo analogue (8c), and the distortion is less recognized. Finally, short sequences of aza-pseudopeptides containing lysine residues improve CO2 separation when used as additives in Pebax® 1074 membranes. The best membrane performances were obtained with a pseudopeptidic dimer as an additive (6b'; deprotected lysine side chain), with an increase in both ideal selectivity αCO2/N2 (from 42.8 to 47.6) and CO2 permeability (from 132 to 148 Barrer) compared to the virgin Pebax® 1074 membrane.

A series of mixed matrix membranes containing poly (ether-block-amide) Pebax 1657 as matrix and polyethylene glycol (PEG) and Zeolitic Imidazolate Framework-8 (ZIF-8) as additives, were prepared and tested for CO2 separation. The membranes were prepared by solvent evaporation method and were characterized by TGA, DSC, SEM, and gas permeation measurements. The effects of PEG and its molecular weight, and the percentage of ZIF-8 into Pebax matrix were investigated. The results showed that the addition of PEG to Pebax/ZIF-8 blends avoid the agglomeration of ZIF-8 particles. A synergic effect between PEG and ZIF was particularly observed for high ZIF-8 content, because the initial permeability of pristine Pebax was multiplied by three (from 54 to 161 Barrers) while keeping the CO2 selectivity (αCO2/N2 = 61, αCO2/CH4 = 12 and αCO2/O2 = 23). Finally, the mechanism of CO2 transport is essentially governed by the solubility of CO2 into the membranes. Therefore, this new Pebax/PEG/ZIF-8 system seems to be a promising approach to develop new selective membranes for CO2 with high permeability.

Linear poly(ether-urea-imide)s (PUIs) are attractive multi-block segmented copolymers well-known for high selectivity for CO2 separations. Their CO2 permeability generally increases but their selectivity decreases with their polyether soft content limited to 70 wt% to preserve their mechanical properties. In this work, the grafting of a PUI copolymer with PEO-based soft grafts is reported for strongly increasing the membrane properties. The design of the grafted copolymers involved step-growth polymerization, controlled radical polymerization, and "click" chemistry. This strategy ensured the control of grafting rate, graft molecular weight and soft contents varying from 57 to 85 wt%. The membrane properties for CO2 and N2 permeation were correlated to the PUI chemical structure, morphology and soft content. The best membrane properties (PCO2 = 196 Barrer; alpha CO2/N2 = 39 at 2 bar and 35 degrees C) were obtained for PUI-g-1PEDEGA5000 corresponding to the highest grafting rate and graft length. Compared to the non-grafted PUI, the best grafted copolymer had much higher CO2 permeability ( x 17) while the ideal separation factor alpha CO2/N2 was maintained at high level, thus leading to separation properties very close to the Robeson 2008 upper-bound. By allowing very high contents of amorphous soft phase and specific morphology, the new grafting strategy offered high-performance membranes for CO2 capture.

The data contained in this publication refers to a new approach to design composite pervaporation membranes that could be useful in water treatment. The work is based on the rational prediction of the membrane mass transfer coefficient using the resistance in series model and the corresponding experimental membranes were tested with several aqueous solutions comparatively to a commercially available porous distillation membrane (PVDF). All the related data, i.e. permeation water fluxes and conductivity of the permeate, were collected for hours, in the range 3 to 7 h. The strategy was to develop pervaporation membranes by coating a porous PVDF support (122µm) with various dense layers (hydrophobic polymers: Teflon™ AF2400, PMP, PTMSP). The objective was to avoid definitely the wetting problem observed in membrane distillation while keeping approximately the permeance than the porous support. The data reported here are related to the surface property of the membranes (contact angles), to the mechanical resistance of the membranes, to the wetting phenomena observed directly and recorded by observing the variation of water flux through the membranes and to the conductivity of the water condensed at the permeate side.

Pervaporation (PV) has mainly been used for dehydration in industrial applications as well as for the recovery of some organic components from various organic or water mixtures. Nevertheless, to date, pervaporation has never been seen as a potential industrial solution to get drinkable water by water permeation, contrarily to membrane distillation (MD). Nevertheless, at the lab scale, some studies with hydrophilic PV membranes have been reported. This work intends to underline the potential industrial interest of hydrophobic PV composite membranes for desalination. Indeed, even in hypersaline solutions, the water activity remains very high (>0.9), and it is wise to use membranes with stable properties in water to guarantee steady performance. Therefore, this study investigates the interest of hydrophobic polymers as coating selective layers for desalination. To guide our choice, a rational approach was used based on the prediction of the membrane resistance to water transfer. Polymethylpentene, poly(1-trimethylsilyl-1-propyne) and Teflon™ AF2400 were tested as the top layer to obtain hydrophobic composite PV membranes. Several feed NaCl solutions with or without a surfactant were used to investigate the mass transfer properties of these PV membranes for water treatment comparatively to more conventional porous membranes (e.g. PVDF) currently studied in membrane distillation.

Linear poly(ether-urea-imide)s (PUIs) are attractive multi-block segmented copolymers well-known for high selectivity for CO2 separations. Their CO2 permeability generally increases but their selectivity decreases with their polyether soft content limited to 70 wt% to preserve their mechanical properties. In this work, the grafting of a PUI copolymer with PEO-based soft grafts is reported for strongly increasing the membrane properties. The design of the grafted copolymers involved step-growth polymerization, controlled radical polymerization, and “click” chemistry. This strategy ensured the control of grafting rate, graft molecular weight and soft contents varying from 57 to 85 wt%. The membrane properties for CO2 and N2 permeation were correlated to the PUI chemical structure, morphology and soft content. The best membrane properties (PCO2= 196 Barrer; αCO2/N2 = 39 at 2 bar and 35°C) were obtained for PUI-g-1PEDEGA5000 corresponding to the highest grafting rate and graft length. Compared to the non-grafted PUI, the grafted copolymers had much higher CO2 permeability (×17) while the ideal separation factor αCO2/N2 was maintained at high level (≅ 40), thus overcoming the permeability-selectivity trade-off. By allowing very high contents of amorphous soft phase and specific morphology for the grafted copolymers, the new grafting strategy offered high-performance membranes for CO2 capture.

Most of the porous supports are prepared by phase inversion method by using classical and toxic solvents: NMP, DMF, THF, DMSO, ... These supports present 95?99% of total thickness and the active layer presents only 0.1 1?3 ?m. It is necessary to find new green method and material to prepare these supports. This paper describes the possibility to use a biodegradable polymer polyvinyl alcohol (PVA) to prepare porous support by using water as a solvent and aqueous or alcohol solutions as a coagulation bath. The SEM microscope is used to study the influence of the composition of polymer solution and the coagulation bath on the structure of prepared membrane. In addition, the life cycle assessment (LCA) tool is used to evaluate the environmental impacts for different preparations and compared with others from bibliography. Finally, a membrane with PVA dense and porous structure was prepared.

La pervaporation est un procede de separation de melanges liquides par transfert selectif au travers d’une membrane organique ou inorganique, poreuse ou non, dont la face aval est generalement maintenue sous basse pression. Particulierement bien adaptee a l’extraction d’un compose minoritaire, elle permet alors une economie d’energie importante par rapport a la distillation. Cet article decrit ses principaux atouts, les membranes utilisees et les separations d’interet. Les principales applications industrielles, les procedes correspondants, leur simulation et analyse technico-economique sont aussi presentes, ainsi que les perspectives R&D notamment dans la petrochimie et les biotechnologies.

To match simultaneously the climate change mitigation with the increasing global demand for energy is a tremendous paradox for this century. To satisfy both criteria, carbon capture seems to be a mandatory technology for the development of sustainable energy infrastructures. Post-combustion capture is a mature and proven technology, but not economically attractive unless novel solvents and optimized processes are implemented. The use of carbonic anhydrase, inspired by the CO2 metabolic process in cells, a natural fast biocatalyst, is a promising technique which can dramatically improve the implementation and economics of carbon capture under stringent environment demands. In this tutorial review, the authors address the state of the art of the carbonic anhydrase-driven processes for carbon capture, recent developments, current and prospective research and engineering achievements.

When pure propane contained in pipelines or storage tankers has to be flushed out by nitrogen fluxes for maintenance purpose, propane recovery is obviously of interest both for environmental issue and for propane valorization. A low temperature condensation is generally used for that purpose and is attractive because it allows to recover propane under liquid state. However, the energy required is very important to reach a high recovery separation target. An alternate approach can be the combination of a nitrogen or propane permselective membrane with a conventional condensation step to improve the global efficiency of the separation process. The present work has been intended to investigate this approach and evaluate to which extent a hybrid process can bring an added value. This study shows first a map of membrane separation performance of propane over nitrogen from data of the open literature. Interestingly it shows that either N-2-selective or conversely, propane selective membranes can be used and also that propane selective membrane will require higher area for atmospheric down-stream pressures (1 bar) compared to down-streams kept at lower pressures (0.1 bar). The selection of the most nitrogen and propane selective membrane is used in order to simulate hybrid processes where separations performances (purity of the propane condensed versus energy required) are compared to the baseline cryogenic standalone process. For low propane contents in the feed mixture (X-in,(C3H8) = 0.5 and 5% mol/mol), it is shown that the use of a propane selective membrane module with a vacuum system seems to be the most energy efficient process while reaching a high purity (> 98%). Based on rigorous process simulations, other hybrid processes cases were performed considering SSZ-13 zeolite membranes and the different separation performances are discussed. It is shown that a membrane/cryogenic process can indeed be less energy demanding to recover propane from N-2-vents. However, according to the recovery target the choice of the membrane type can vary from an organic to a zeolite membrane.

ABSTRACTFew commercially available membranes can be used for organic solvent nanofiltration (OSN). Applying OSN in chemical industries is nevertheless of high interest to cut with energy consumption linked to solvent recycling and soluble catalysts recovery. A commercial membrane, PERVAP4060, was used to investigate the retention of dilute solutes in toluene feeds and to mimic metathesis medium. The studied solutes were R‐BINAP a neutral polyaromatic molecule used in metathesis chemistry, tetraoctylammonium bromide (ToABr), a charged molecule used as a homogeneous catalyst and n‐hexadecane. Retention of polar ToABr (95%) was higher than that of neutral R‐BINAP (80%). The transfer mechanism, either pore flow or solution‐diffusion, was discussed. All the results obtained suggested that the transport is governed by the solution‐diffusion mechanism. The measured retentions could be explained in terms of solubility affinities and diffusion coefficients. The stability and performances of PERVAP4060 were well established, showing the strong potential for industrial applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48359.

The so-called Graftfast reaction in water and at room temperature (RT) was applied to graft polyethylene glycol (PEG) at the surface of the microporous zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) using acrylPEG of different chain lengths (480 Da and 5 kDa). In comparison to nonmodified ZIF-8 NPs, both chemical and colloidal stabilities of PEGylated ZIF-8 NPs are significantly enhanced in water. A series of colloidal complex fluids by mixing PEG grafted ZIF-8 (i.e., PEG-g-ZIF-8) NPs with different amounts of poly(vinyl alcohol) (PVA) was prepared and characterized by advanced characterization tools such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) thereby showing their long-term colloidal stability. Finally, dense and supported mixed matrix membranes were cast from PEG-g-ZIF-8/ PVA solutions and have shown high performance in isopropanol (IPA) dehydration by pervaporation. The permeation flux of the supported MMM (i.e., 0.091 kg/(m(2).h)) is 11 times higher than that of the pure PVA membrane and these MMMs present a high separation factor (i.e., 7326). These transport properties are presumably due to the molecular sieving effects induced by ZIF-8 and the good interfacial properties of the membrane. The computational exploration of the ZIF-8/PVA and PEG/PVA interfaces provides a microscopic scale explanation for the enhanced compatibility of PVA with the PEGylated MOF when compared to that for the composite based on the bare ZIF-8 as a filler.

Graft copolymers of natural rubber (NR) and poly-3-hydroxybutyrate (PHB) with 60: 40 ratio were synthesized in chlorobenzene. Two types of initiators namely azoisobutyronitrile (AIBN) and benzoyl peroxide (BPO) AIBN and BPO were employed to initiate the free radical grafting of the two polymers. The influence of the various types of initiator loadings was also investigated. Estimation of the grafted NR was performed using FTIR. The thermal stability and crystallization behavior of NR-g-PHB was studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) TGA as well as DSC respectively. The absence of the C=C peak of NR in the FTIR spectra confirmed that PHB grafted on this site after the breakage of the C=C bond. The increase in initiator loading, improved the smoothness of the NR-g-PHB. Moreover, single Tg were observed for NR-g-PHB which indicate that no phase separation occurs and the thermal stability of pristine NR after grafting was improved compared with that of NR alone.

High selective polymers are bound to exhibit low intrinsic permeability. To mitigate this issue, thin film composite (TFC) membrane has been proposed whereby high selectivity, low permeability thin polymer layers are deposited on top of a thicker, highly permeable (even porous) materials. Nevertheless, deposition of thin film can be complicated on these structures due to limitation of fabrication methods (pore intrusion and support resistance to thin film solvent) and/or reduction of permeation efficiency (lateral diffusion). In this work, the potential of commercial Oxyplus (R) hollow fibre membrane as support-gutter layer was studied. Polymethylpentene (PMP), the material of the dense skin in Oxyplus has high gas permeability yet glassy enough to be self-standing, making it a possible candidate as a combined support-gutter layer. Ten fibres were potted together, assembled into a module, and tested in dead-end mode under 1-5 bar transmembrane pressure for CO2, CH4 and N-2 gases. The permeances were registered at 607.3 +/- 31.3 GPU, 156.0 +/- 13.1 GPU, and 84.6 +/- 6.2 GPU, respectively, equivalent to a separation factor of 7.4 +/- 0.4 (CO2/N-2), 4.0 +/- 0.2 (CO2/CH4) and 0.6 +/- 0.1 (N-2/CH4). With dense skin layer thickness of 0.1 +/- 0.1 mu m, these values are comparable to the PMP results in literatures and are suitable as support-gutter layer for low permeability polymers such as P84 (R) polyimide.

In this work, dense and supported pervaporation polyvinyl alcohol (PVA)-based membranes modified with poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate)(PSS)/PAH top nanolayers were synthesized. Two main points were investigated: the role of the polyelectrolyte PAH on water selectivity of the selective polymer matrix and the impact of the porous substrate based on polyacrylonitrile (PAN) and aromatic polysulfone amide (UPM-20®), used to get supported high-performance membranes. Various methods of analysis (fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), porosity, contact angles, ultrafiltration) were applied to study the developed membranes. Transport characteristics of the developed membranes were studied in isopropanol dehydration by pervaporation. Obtained results are discussed in the light of the structure and physicochemical characteristics of these PVA/PAH membranes and the types of porous substrate. It was shown that the PAN-supported membrane with the selective layer based on PVA/PAH modified by 10 polyelectrolyte PSS/PAH bilayers possessed ~4.5 times higher permeation flux with the same high selectivity level (99.9 wt % water in the permeate) for the dehydration of the isopropanol (20 wt % water) at 60 °C compared to the commercial analog PERVAPTM 1201.

New functionalized poly(dimethylsiloxane) (PDMS) membranes were prepared by the surface modification of the commercially available PERVAP4060 membrane (Sulzer (TM)) through cold plasma activation followed by the layer-by-layer assembly method. Four different pairs of polyelectrolytes, i.e., poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA), PAH/poly(sodium 4-styrene sulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDDA)/PAA, and PDDA/PSS, were used to coat the PDMS layer by the controlled deposition of successive nanolayers (20-50 nm). PERVAP4060 was systematically modified by the deposition of 10 bilayers of polyelectrolyte pairs. These membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), ellipsometry, and atomic force microscopy (AFM). The nanofiltration membrane performance for the rejection of four diluted solutes-two soluble catalysts 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (R-BINAP) and tetraoctylammonium bromide (ToABr) and two linear aliphatic molecules n-Tetratetracontane (C44H90 or C44) and n-Hexadecane (C16H34 or C16)-was studied in the toluene feed solution at up to 40 bar pressure. It was shown that the organic solvent nanofiltration (OSN) mass transfer properties differ clearly depended on the layer-by-layer chemical structure and the characteristics of the solutes. Thus, the intrinsic permeance of toluene in the PEL multilayers were calculated by applying resistance-in-series model. Despite the highly diluted concentrations of the solutes, i.e., < 1 wt% for R-BINAP and ToABr, and the high solvent permeate flux, the ToABr, R-BINAP, and C44 solutes were markedly rejected by all the membranes. ToABr had the highest rejection coefficient, up to 97%. As a trend, higher the polarity of the bilayer assembly, lower was the mass transfer of the solvent compared to that of the pristine membrane. The results indicated that a solution-diffusion mechanism is likely to apply. The best rejection of R-BINAP (up to 88%) was obtained when the membrane was coated with 10 bilayers of PAH/PSS. Thus, these prepared polyelectrolyte (PEL)-modified membranes have potential applications in homogeneous catalysis industry, for example in olefin metathesis for expanding the lifetime of soluble catalysts by separating them at mild OSN condition while ensuring the permeation of products.