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The batch and continuous synthesis of glycolic acid via carbonylation of formaldehyde using high-temperature and high-pressure poly(tetrafluoroethylene) (PTFE) membrane contactor was demonstrated in this paper. The experiments in conventional stirred tank reactor were also conducted for comparison. The results showed that the yield of glycolic acid was significantly improved in membrane contactor system compared to the stirred tank reactor. At reaction temperature of 120 °C and reaction pressure of 5.0 MPa, the yield of glycolic acid was higher than 90% when the reaction time was 1 h, while it was only about 45% in the conventional stirred tank reactor. The enhancement of yield was due to the improvement of mass transfer or dispersion of CO in membrane contactor system, which could provide larger gas-liquid contact area and shorter mass transfer distance. The stability of PTFE hollow fibre membranes was also investigated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), liquid entry pressure (LEP), bubble point (BP) and contact angle (CA) measurements. The characterizations indicated that PTFE membranes exhibited good chemical and thermal stability in this reaction system. This study provided new idea and reference for the carbonylation of formaldehyde and similar gas-liquid reactions. • Batch and continuous synthesis of glycolic acid via carbonylation of formaldehyde in membrane contactor was demonstrated. • Mass transfer of CO is greatly enhanced in membrane contractor system compared to the conventional tank reactor. • Membrane contactor can provide larger contact area and shorter diffusion path for gas-liquid reaction. • PTFE hollow fibers exhibited good stability under high temperature and high pressure conditions. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel acyl chloride monomer trimellitic anhydride chloride (TAC) with an anhydride group was blended with trimesoyl chloride (TMC) as organic phase monomers to fabricate high-flux nanofiltration membranes. Due to the reaction activity differences of organic phase monomers (TMC and TAC) with piperazine, the chemical compositions and structures of polyamide active layer could be tailored through varying the TAC content. It was found that the participation of TAC could yield a looser polyamide separation layer on the polysulfone support membrane, along with an increased surface roughness, hydrophilicity, pore size and negative charge density. As a result, the resultant membrane exhibited excellent water-salt separation. When the TAC concentration was increased to 0.04 wt%, the optimized membrane exhibited a high pure water permeability (PWP) of 13.2 L m−2 h−1 bar−1, up to 2-fold, in comparison with the pristine membrane, whereas the salt rejections of Na 2 SO 4 , MgSO 4 and NaCl were 97.6%, 92.7%, and 34.0%, respectively. This work provided a novel and facile strategy to develop high-flux NF membrane. Highlights • NF membranes were prepared with mixed organic phase reactants of TMCand TAC with an anhydride group. • Membrane physicochemical properties and permselectivity were tuned by varying the TAC content. • The water flux of optimal NF membrane was 2 times to that of controlled membrane under the almost same salt rejections. [ABSTRACT FROM AUTHOR]

Abstract: A series of crosslinked poly(ethylene glycol) diacrylate (PEGDA, MW=302g/mol) membranes were prepared via UV-induced polymerization by adding various ethanol in prepolymerization solution. Membrane surface morphology, interior structure, chemical composition and mechanical property were investigated with scanning electron microscope (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and tensile tester. The results suggested that decreasing PEGDA content in prepolymerization solution could gradually enlarge the pore size in the surface and the bulk of membranes, resulting in a higher water uptake and permeability, but a lower bovine serum albumin (BSA) rejection. Meanwhile, the mechanical property decreased. Specifically, when the PEGDA content in prepolymerization solution changed from 100wt% to 45wt%, the pure water flux of membranes increased from zero to 340L/m2 h at 0.1Mpa. Finally, the BSA fouling and preliminary solvent soaking experiments also indicated that such membranes exhibited excellent antifouling and solvent-resistant properties. [Copyright &y& Elsevier]

Nafion-PTFE hollow fiber composite membranes were fabricated and applied in vacuum membrane distillation (VMD) process to improve the anti-fouling and anti-wetting performance in the presence of oil and surfactant. The composite membrane exhibited an underwater super-oilphobic property according to the contact angle test. The VMD performance when treating saline feed containing 3.5 wt% NaCl and 1000 ppm mineral oil for the composite membrane behaved a stable flux for 40 h. In construct, an immediate and sharply-declined flux was observed for the pristine PTFE, indicating the significant improvement in the anti-fouling property. Meanwhile, the composite membrane also alleviated the wetting phenomena caused by the surfactant comparing with the pristine PTFE membrane, and the Nafion-PTFE composite membrane behaves a stable flux and high salt rejection higher than 99.99% for 60 h treating saline feed containing O/W emulsions. The pressure depression effect of the Nafion layer on the mass transfer was analyzed. It was found that the depression could be reduced with the increasing of the feed temperature and the enhancement of the corresponding effective pore diameter of the Nafion layer, that the pressure depression factor decreased from 0.23 to 0.04 with the feed temperature increasing from 60 °C to 75 °C. Image 1 • An asymmetric composite membrane with a thin Nafion layer on the outside of a PTFE membrane was fabricated for VMD. • The application of Nafion-PTFE membrane to VMD was first studied and reported. • The Nafion-PTFE composite membrane showed good anti-fouling and anti-wetting property. [ABSTRACT FROM AUTHOR]

Abstract: A new kind of zwitterionic molecule, [3-(methacryloylamino)propyl]-dimethyl (3-sulfopropyl) ammonium hydroxide inner salt (MPDSAH) was grafted onto polysulfone (PSF) ultrafiltration membrane surface using benzophenone (BP) as the initiator to improve the antifouling property. Polymer chain scission was suppressed by H-abstraction from methyl groups under long-wavelength UV irradiation (λ >300nm), which avoided the photodegradation of PSF ultrafiltration membrane. The effects of MPDSAH concentration, UV irradiation time and BP concentration on grafting degree (GD) and the improvement of membrane antifouling properties were investigated, respectively. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR/ATR) and scanning electron micrograph (SEM) were used to characterize the chemical and morphological changes of the membrane surface. Static contact angle (CA) measurements showed that the hydrophilicity of MPDSAH-modified PSF ultrafiltration membranes was enhanced with the increase of grafting degree. The flux of pure water decreased slightly after modification, while the rejection to bovine serum albumin (BSA) increased. The improvement of antifouling property for MPDSAH-modified membrane was accordant with the increase of grafting degree. In addition, compared to PSF membrane, the modified membranes could maintain a higher water flux in wide pH range. [Copyright &y& Elsevier]

High-performance semi-permeable membranes play a vital role in the membrane-based separation technology for seawater and brackish water desalination. Herein, plasticizer-assisted interfacial polymerization (PAIP) was implemented to fabricate aromatic polyamide layers with improved water flux and comparable salt rejection for the first time. Specifically, plasticizer (i.e., diethyl phthalate, DEP) was introduced into the organic phase to perform interfacial polymerization. Effective regulation of the desalination performance was achieved via meticulously adjusting plasticizer concentration. With the addition of 0.5 wt% DEP, water flux promoted from 1.06 L m−2 h−1 bar−1 of the pristine membrane to 2.85 L m−2 h−1 bar−1, with NaCl rejection decreasing from 98.3% to 98.2%. With the addition of 1.5 wt% and 2.0 wt% DEP, water flux improved to 4.82 L m−2 h−1 bar−1 and 5.95 L m−2 h−1 bar−1, respectively, more than 4.5 and 5.5 times that of the pristine membrane. Nevertheless, NaCl rejection decreased to 96.6% and 95.9%, respectively. The infrared detection revealed that the introduction of DEP disrupted the original intermolecular hydrogen bonding between polyamide chains, thereby enhancing the softness of the polyamide layer, which was demonstrated by the decreased Young's modulus. As a result, the water diffusion efficiency through the polyamide layer was promoted, leading to the significant enhancement of water flux. These findings pave a new route for the synthesis of the aromatic polyamide layer with excellent desalination performance to expand the application of membrane technology. Image 1 • Plasticizer-assisted interfacial polymerization was developed to prepare RO membranes. • Polyamide chain flexibility improved substantially in the presence of plasticizer. • Disruption of inter chain hydrogen bonding caused enhancement of chain flexibility. • Water flux enhanced due to more efficient transport channels for water molecules. [ABSTRACT FROM AUTHOR]

The considerable permeability of fully-aromatic polyamide reverse osmosis (RO) membranes is believed to be strongly dependent on the presence of a mount of internal voids within the polyamide separation layer, which provides additional permeation channels in addition to diffusion through the polyamide matrix. Based on this understanding, herein, we reported a novel strategy of developing highly permeable RO membranes via introducing a void-tailoring agent, (3,3,3-trifluoropropyl)trichlorosilane (TFPTCS) into the traditional interfacial polymerization (IP) system composed of m-phenylenediamine and trimesoyl chloride. During IP process, the fast and violent hydrolysis and aminolysis of TFPTCS caused a significantly increasing pore size and porosity of the incipient polyamide film, which resulted in the formation of double- or multi-layer void structures with higher void fraction in the polyamide film. As a result, the TFPTCS added membrane showed a dramatic enhancement in water permeability, and the optimum condition was observed at the 0.03 wt% of TFPTCS concentration with 3.74 L m−2 h−1 bar−1, which was 2.8 times higher than that of the pristine membrane, while the salt rejection was almost unchanged (around 97.0%). These findings demonstrate the feasibility of void-tailoring inside the polyamide film, and encourage further exploration of new alternative void-tailoring agents to prepare highly permeable polyamide RO membranes for water desalination, which were seldom studied previously. • TFPTCS was introduced into the traditional MPD-TMC IP system to tune the internal void structure of the formed PA films. • The addition of TFPTCS led to an increase in the void volume within PA films, the pore size and porosity of PA back face. • The modified membrane showed a 2.8-fold improvement in water permeability without the loss of salt rejection. [ABSTRACT FROM AUTHOR]

Abstract Within a microporous polymer membrane, its high gas separation performance is much dependent on the free volume element architecture. In this study, thermally rearranged poly(benzoxazole-co-amide) (TR-PBOA) copolymer membranes were prepared by in-situ thermal treating poly(o-hydroxyamide- co -amide) (PHAA) precursors, basing on commercially available TR-able and non TR-able diamines with different molar ratio. Free-volume topologies were tailored by controlling the degree of thermal rearrangement and the flexibility of the original chains. Upon thermal conversion, small cavities coalesced into bigger ones, representing hourglass-shaped cavities with larger cavities and small bottlenecks, resulting in the significant increase in permeability. It was found that thermal rearrangement mainly occurred near or above glass transition temperature (T g) where chain segments obtained enough motion ability, and TR-PBOA membrane prepared at this temperature possessed the maximal selectivity due to effective packing of rigid chains. When thermally treated at temperature much higher than T g , there was a compromise between thermal conversion and chain annealing. Compared to thermal treatment temperature, the effect of dwelling time on thermal conversion ratio was minor, as the formed rigid structure limited chain motion until enough energy was received at higher temperature. Furthermore, TR-PBOA membranes with appropriate ratio of PBO and PA contents displayed superior mechanical properties and gas transport performance, especially for CO 2 /CH 4 separation (CO 2 permeability was about 237 Barrer, CO 2 /CH 4 ideal selectivity was 36.6, plasticization pressure of CO 2 was 2.9 MPa) (1 Barrer=10−10 cm3 (STP) cm cm−2 s−1 cmHg−1) Highlights • TR-PBOA copolymer membranes were prepared by in-situ thermal treating PHAA precursors. • Thermal rearrangement mainly occurred near or above glass transition temperature. • The effect of dwell time on thermal conversion ratio was minor. • TR-PBOA membranes displayed superior CO 2 /CH 4 separation performance. [ABSTRACT FROM AUTHOR]

Membrane separation technology is one of the most promising strategies for post-combustion CO 2 capture. The high-performance membrane module is one of the most critical components in the CO 2 capture membrane system. The spiral-wound module is a promising type for industrial application; however, most of the research remains in the laboratory. In this work, industrial-scale spiral-wound membrane modules containing facilitated transport membranes have been developed and investigated. Under given practical operating conditions, an apparent gas separation performance was defined as an indicator to study the effects of various feed conditions on membrane performance within the module. As a crucial process parameter, the operating pressure was considered a variable to investigate the module performance at a fixed feed-to-permeate pressure ratio, and techno-economic indicators were also studied. Furthermore, a multi-core module containing up to 14 membrane elements was designed based on the experimental results of the arrangement mode cases. This work could bridge the research gap between membrane development and membrane system engineering. It could also provide essential data for the industrial application of post-combustion CO 2 capture. [Display omitted] • The industrial-scale spiral-wound membrane module was developed. • An apparent gas separation performance was defined to investigate feed conditions. • The effects of operating pressure and arrangement mode were discussed. • A multi-core membrane module containing up to 14 elements was designed. [ABSTRACT FROM AUTHOR]

Extraction of lithium from salt lakes is an important route for lithium sources. Due to the unique structure and separation mechanism, i.e., size exclusion and Donnan effect, nanofiltration (NF) is considered as a promising way to separate magnesium (Mg2+) and lithium (Li+) ions. However, the Mg2+/Li+ separation factor of NF membrane fabricated by traditional interfacial polymerization (IP) is usually dissatisfactory. Here, a swelling-embedding-shrinking strategy was proposed to modify polyethyleneimine (PEI)/trimesoyl chloride (TMC) NF membranes using diethylenetriamine (DETA) to improve the performance in Mg2+/Li+ separation. The pristine PEI/TMC NF membrane was swollen with methanol to increase the polyamide chain spacing followed by embedding electropositive DETA as a modifier. The charge properties and pore structure of the active layer could be regulated by optimizing the modification conditions. Within comparison to the pristine membrane (TFC-0), the pure water flux of modified NF membrane (TFC-3) increased by 63.6% because of the rougher surface and the larger pore size. Meanwhile, the embedding of electropositive DETA reduced the electronegative property of membrane surface. In consequence, TFC-3 membrane exhibited higher rejection of MgCl 2 (93.9% against 88.4%) and lower rejection of LiCl (31.0% against 32.1%), thus showing a twofold improvement in Mg2+/Li+ separation factor (S Li, Mg = 11.38 against 5.87). The swelling-embedding-shrinking strategy in this article provided a good reference for the modification of NF membranes in the separation of multivalent and monovalent ions. [Display omitted] • A swelling-embedding-shrinking strategy was proposed to enhance membrane performance. • Surface property and pore size could be regulated by embedding diethylenetriamine (DETA). • Modified PEI/TMC NF membrane had higher rejection of Mg2+ but lower rejection of Li+. • Mg2+/Li+ separation factor reached up to 11.38 compared to 5.87 of pristine membrane. [ABSTRACT FROM AUTHOR]

Nanofiltration is considered a promising technology for separation of multivalent/monovalent ions such as extracting lithium from Salt Lake brine with high Mg2+/Li+ ratio. However, the nanofiltration membranes fabricated via conventional interfacial polymerization process generally possess negatively charged surface and have low Mg2+/Li+ selectivity. Herein, we proposed a new and facile method, i.e., reversed interfacial polymerization (RIP), to prepare nanofiltration membranes with positively charged surface and uniform charge distribution. The sequence of amine (polyethyleneimine, PEI) and acyl chloride (trimesoyl chloride, TMC) monomers on polysulfone support was reversed compared to the conventional interfacial polymerization (IP) process. Moreover, the solvent of amine monomer was acetone instead of water. The nanofiltration membranes fabricated by this method exhibited higher water flux (from 4.88 to 22.25 Lm−2h−1) and MgCl 2 rejection (from 84.36% to 97.71%). Meanwhile, LiCl/MgCl 2 separation factor in single salt solution reached up to 13.93, which was almost quadruple compared to the conventional control membrane. In addition, the developed nanofiltration membrane also exhibited an excellent separation selectivity (S Li, Mg = 9.22) in mixture system (Mg2+/Li+ mass ratio of 20), which had good application potential in extracting lithium resources from Salt Lake brine. [Display omitted] • A facile reversed interfacial polymerization (RIP) method was proposed. • Positively charged nanofiltration membranes with uniform charge distribution. • Acetone was selected as solvent of polyethyleneimine monomer instead of water. • Mg2+/Li+ selectivity reached 13.93 and 9.22 in single and mixed salt system, respectively. [ABSTRACT FROM AUTHOR]

Calcium carbonate (CaCO 3 ) nanoparticles were used as sacrificial additives to fabricate PSf substrate membranes and based on which thin film composite (TFC) membranes were prepared using m-Phenylenediamine (MPD) and 1, 3, 5-trimesoylchloride (TMC) as the monomers. Then CaCO 3 nanoparticles dispersed in PSf matrix were effectively etched with hydrochloric acid to increase the substrate porosity. The effect of CaCO 3 loading (ranging from 0 to 10.0 wt%) was systematically investigated. The results showed that the substrate membranes fabricated with CaCO 3 incorporation exhibited higher porosity and smaller structural parameter, which is advantageous for improving water permeability and reducing mass transfer resistance. As for forward osmosis (FO) performance, the TFC membranes fabricated using modified substrates exhibited much higher water flux than the control TFC membrane prepared by substrate without CaCO 3 incorporation in both AL-FS and AL-DS mode when using DI water as the feed and 2 M NaCl as draw solution. The optimized TFC21 membrane also had better performance than other commercial TFC membranes in simulated seawater desalination. Moreover, the reduced membrane structural parameter indicated that the internal concentration polarization (ICP) could be mitigated via the etching method. This study provides a low cost and feasible way to reduce the ICP in FO membranes. [ABSTRACT FROM AUTHOR]

Abstract: A novel nanofiltration membrane prepared by interfacial polymerization of purposefully synthesized polyhexamethylene guanidine hydrochloride (PHGH) with antibacterial property and trimesoyl chloride (TMC) on polysulfone (PSf) ultrafiltration membrane was investigated. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM) and atomic force microscopy (AFM) were employed to characterize the chemical structures and morphologies of the active layers of obtained membranes. The effects of monomer concentrations, reaction time, curing temperature and time on filtration performance of the composite nanofiltration membranes were discussed. It was found that the membrane rejections to different salts followed the order of MgCl2>MgSO4>Na2SO4>NaCl. Dyes rejection results further showed the feasibility for the membranes to separate small organic molecules with a molecular weight cut-off (MWCO) of around 700Da. Antibacterial experiments indicated that the newly prepared composite nanofiltration membrane had effective inhibition against Escherichia coli. Furthermore, a 50h fouling test using high concentration of bacteria solution also demonstrated an enhanced anti-biofouling performance of the composite nanofiltration membrane. [Copyright &y& Elsevier]

The enhancement in selectivity of nanofiltration (NF) membranes is of great significance for extending the application areas and improving the process economy, especially for the separation of monovalent/divalent ions. The characteristics of moderately increased pore size, fewer nonselective defects and a more uniform structure are conducive to NF membrane exhibiting higher rejection of divalent ions but lower rejection of monovalent ions. Nonylphenol polyoxyethylene ether (NP-10) was introduced in interfacial polymerization process in this study to optimize the microstructure and surface properties of polyamide (PA) layer to manufacture highly selective NF membranes. The hydrophobic benzene ring and aliphatic chain in NP-10 could form a local space that restricted the interfacial polymerization reaction on the side of the oil phase, thereby appropriately increasing the pore size of the PA layer. It was advantageous to the permeation of water molecules and monovalent ions with a smaller radius. The long hydrophilic oxyethylene group as a guide could facilitate the uniform diffusion of the monomer to the water/hexane interface. NP-10 as an amphiphilic substance would form a self-assembled network at the water/hexane interface, which was expected to optimize the distribution of aqueous amine monomers at the phase interface. Meanwhile, introducing NP-10 can form a stable interface and reduce the interface disturbance, thus inhibiting the formation of non-selective macropores (or "defects") in PA layer, which could improve the separation selectivity of monovalent/divalent ions. In addition, the hydrophilicity and electronegativity were also enhanced. The results showed that the MWCO of NF membrane increased from 210.1 Da (TFC-0) to 269.6 Da (TFC-0.25), and the average pore radius increased from 0.248 nm to 0.276 nm. The water flux of optimized membrane was doubled compared to the control membrane. Most important, the optimized exhibited higher rejection of divalent Na 2 SO 4 (from 98.07% to 99.43%), and meanwhile lower rejection of monovalent NaCl (from 54.07% to 27.52%). NaCl/Na 2 SO 4 separation factor reached up to 130.53, which was about four times of TFC-0 membrane. [Display omitted] • Separation factor (NaCl/Na 2 SO 4) reached up to 130.53. • Higher rejection of divalent ions but lower rejection of monovalent ions. • Moderately increased pore size, fewer defects, and uniform structure. • Restricted IP reaction to appropriately increase the pore size of PA layer. • A stable interface and reduce the interface disturbance. [ABSTRACT FROM AUTHOR]

Abstract: A hollow fiber composite membrane was prepared by coating a poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate) (PDMAEMA–PEGMEMA) skin layer onto a porous polysulfone (PSf) substrate. The influence of fabrication parameters including coating solution concentration and coating times on the permselectivity of the prepared membrane was investigated. For the composite membrane prepared from the optimal fabrication parameter, its CO2 permeance was about 30GPU with CO2/N2 selectivity of 31 at 35°C and 202.65kPa. Moreover, the effects of experimental temperature and pressure on the permselectivity of hollow fiber composite membranes were evaluated. The gas permeance increased with the increase of temperature, which obeyed Arrhenius relation. With the increase of pressure, N2 showed the similar permeance that meant the transport of N2 through membrane followed solution–diffusion mechanism, while for CO2, its permeance underwent a two step change (first increased then decreased) which suggested there might be two transporting models for CO2 (solution–diffusion and facilitated transport). In addition, it was found that water vapor in the feed gas not only caused plasticization, but also enhanced the interaction of CO2 with amino groups in PDMAEMA–PEGMEMA skin layer. Both of the two effects contributed to a higher CO2 permeance compared with the condition that water vapor was absent. [Copyright &y& Elsevier]

Polytetrafluoroethylene (PTFE) is considered as a promising material for membrane contactors due to its intrinsic hydrophobicity and excellent chemical stability. In most published works concerning CO 2 absorption, PTFE hollow fiber membranes with diameter larger than 1.2 mm even 2.0 mm were applied, which lost the advantage of membrane contactor in high specific surface area and also increased the mass transfer resistance. In this study, biogas purification by membrane contactor was systematically investigated based on the smaller-diameter PTFE hollow fibers (0.9 mm) developed recently in our laboratory. CH 4 –CO 2 (40%) mixture was used as simulated biogas, and deionized water was used as absorbent for all tests. The influence of module configuration, liquid flow pattern, membrane microstructure, and gas-liquid flow velocity on CO 2 removal performance were studied in detail. Moreover, the mass transfer resistance and CH 4 recovery rate were also discussed. CO 2 content in purified biogas could be below 3% by adjusting the operating parameters. CO 2 flux and overall mass transfer coefficient (K OV) under experimental conditions ranged from 0.61 × 10−3 to 1.35 × 10−3 mol/(m2. s) and from 1.67 × 10−5 to 6.34 × 10−5 m/s, respectively. Moreover, CO 2 removal performance was stable in an operation of 36 h. PTFE hollow fibers with smaller diameter exhibited preeminent CO 2 removal efficiency, which proved great application potential in biogas upgrading by membrane contactor. [Display omitted] • PTFE hollow fiber (diameter of 0.9 mm) for biogas upgrading by membrane contactor. • Weaving configuration design of membranes significantly improved mass transfer. • Effects of fluid flow pattern and membrane microstructure were also investigated. • Smaller-diameter PTFE membrane contactor exhibited good application potential. [ABSTRACT FROM AUTHOR]

A versatile pilot-scale two-stage membrane plant for CO 2 capture from different simulated exhaust gases was designed and constructed. The capture efficiency was investigated in detail under different operating pressures, humidifier temperatures, and stage-cuts based on the graded CO 2 contents of the initial feed gas (i.e., 14%, 25%, and 35%), which were similar to the typical CO 2 contents of industrial exhaust gas emitted from coal-fired power plants, steel mill/cement plants, and factories associated with high–CO 2 –concentration operations, respectively. When the CO 2 capture rates were 61.3%, 60.7%, and 53.9% in the three cases, the product gas CO 2 purities could reach 78.5%, 87.2%, and 96.3%, respectively. This study also represents the first instance of developing an actual design and layout of a three-stage and three-step membrane plant, which will be built in early 2021 in Nanjing, China, and is expected to achieve the targets of 95% CO 2 product purity and 90% CO 2 capture rate. The experience gained through this study could accelerate the industrial application of membrane technology for CO 2 capture. Image 1 • A versatile pilot-scale two-stage membrane plant was designed and constructed. • It provided a picture of CO 2 capture covering different industrial occasions. • It was the first time to present an actual design and layout of membrane plant. • The well-designed plant had the potential to approach the DOE's capture target. [ABSTRACT FROM AUTHOR]

Soluble aromatic polyamide films were prepared with different molar ratios of 2,2′-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF) and 3,3′-dihydroxy-4,4′-diaminobiphenyl (HAB), and then in-situ treated at different temperature to obtain thermally rearranged polybenzoxazole (TR-PBO) membranes with ultra-high gas permeability. Compared to polyamide precursors, the obtained TR-PBO membranes exhibited bimodal cavity distribution. The size of smaller cavities, ranging from around 3.3 Å to around 4.1 Å, increased with APAF content. And the larger cavities of 5.6–6.0 Å were almost constant in size, irrespective of thermal treatment temperature or precursor structure. It was found that increasing thermal treatment temperature could prompt smaller cavities to coalesce into bigger ones, thus resulting in better gas permeability. Higher APAF content results in higher gas permeability but inferior resistance to CO 2 plasticization, however, too low APAF content is also not beneficial to plasticization resistance due to the lower thermal conversion ratio caused by close-packed array of HAB-TPC. It was found that with APAF/HAB molar ratio of 5/5, the prepared TR-PBO membranes exhibited better resistance to CO 2 plasticization as well as comparable mechanical properties and stable permeation performance. • Solubility and mechanical properties are optimized by tuning monomer ratio. • Precursor structure only influences the size of smaller cavities. • Increasing TR temperature prompts smaller cavities to coalesce into bigger ones. • TR-PBO membranes display superior resistance to plasticization and physical aging. [ABSTRACT FROM AUTHOR]