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The polydimethylsiloxane (PDMS) membrane commonly used for separation of biobutanol from fermentation broth fails to meet demand owing to its discontinuous and polluting thermal fabrication. Now, an UV‐induced polymerization strategy is proposed to realize the ultrafast and continuous fabrication of the PDMS membrane. UV‐crosslinking of synthesized methacrylate‐functionalized PDMS (MA‐PDMS) is complete within 30 s. The crosslinking rate is three orders of magnitude larger than the conventional thermal crosslinking. The MA‐PDMS membrane shows a versatile potential for liquid and gas separations, especially featuring an excellent pervaporation performance for n‐butanol. Filler aggregation, the major bottleneck for the development of high‐performance mixed matrix membranes (MMMs), is overcome, because the UV polymerization strategy demonstrates a freezing effect towards fillers in polymer, resulting in an extremely high‐loading silicalite‐1/MA‐PDMS MMM with uniform particle distribution. [ABSTRACT FROM AUTHOR]

Abstract Recently much endeavor has been devoted to improving pervaporation performances of polydimethylsiloxane (PDMS) membranes for organic aqueous solutions by doping hydrophobic porous particles. However, the strategy generally promotes water permeation as well, which is contrary to the separation purpose but has not caused researchers' attention. Here, a novel strategy was proposed to improve pervaporation performance by promoting organic permeation and simultaneously inhibiting water permeation via doping organophilic porous particles that have hydrogen bonding interaction sites in pore channels. To test this strategy, COF-300 was synthesized and blended with PDMS to form mixed matrix membranes (MMMs). Pore size distribution, FT-IR, XPS and water adsorption results demonstrated the presence of hydrophilic amino and aldehyde groups in COF-300. Meanwhile, the COF-300 exhibited ultrahigh affinity toward furfural with a maximum adsorption capacity of 525.3 mg g−1 at 80 °C. Pervaporation experiments showed that COF-300 promoted permeations of furfural and other organics including aniline, butanol, ethanol and phenol but inhibited water transport. The reduced water permeability was attributed to the hydrogen bonding between water molecule and COF-300, which increased the mass transfer resistance of water molecules. Compared to the pure PDMS membrane, the 8 wt% COF-300/PDMS MMM displayed an increment of 14.1% in furfural permeability but a diminution of 20.0% in water permeability when separating a 1.0 wt% furfural aqueous solution at 80 °C. As a result, an increase of 42.7% in the furfural selectivity was obtained, demonstrating the feasibility of the proposed strategy and the high potential of COF-300 in fabricating MMMs for pervaporation separation of organic aqueous solutions. Graphical abstract Image 1 Highlights • PDMS/COF-300 matrix mixed pervaporation membranes were prepared. • COF-300 greatly enhances furfural solubility in mixed matrix membranes. • PDMS/COF-300 membranes show high permeabilities to organics due to high organo-affinity and open pore channels of COF-300. • Water transport is limited because of hydrogen bonding between water and COF-300. • COF-300 increases furfural/water selectivity by 42.7% of the pristine PDMS. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Use polydopamine to endow ZIF-8 particles with chemically reactive surfaces. • Enhance the hydrophobicity of hydrophobic ZIF-8 particles by a silane modification. • The enhanced hydrophobicity is favorable for the PV performance of MMMs. • An increase of 23% in separation factor compared to the ZIF-8/PDMS membrane. Abstract The hydrophobicity of porous particles is important for the performance of mixed-matrix membranes for pervaporation separation of n -butanol aqueous solution. Here, a strategy was proposed to further enhance the hydrophobicity of ZIF-8. ZIF-8 particles were first coated by polydopamine (PDA) to create chemically reactive surface and then modified with silane coupling agents n -propyltrimethoxysilane and n -octyltriethoxysilane. The water contact angles of the obtained P-ZIF-8@PDA and O-ZIF-8@PDA separately increased from 132.8° to 137.3° and 151.5°, which demonstrated a remarkable enhancement in hydrophobicity. The silane-modified ZIF-8 particles were subsequently incorporated into PDMS to fabricate mixed-matrix membranes, which exhibited an improved adsorption selectivity for butanol. The best membrane with 1 wt% loading (O-ZIF-8@PDA) exhibited a separation factor of 56 and butanol flux of 480.6 g m−2 h−1 for a 1.5 wt% butanol solution at 55 °C. The separation factor increased by 23% compared with that of a ZIF-8/PDMS membrane. Moreover, compared with those of a pure PDMS membrane, the separation factor and butanol flux increased by 34% and 85%, respectively. Thus, the strategy is an effective method to improve the PV performance of PDMS membranes for butanol separation. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) membrane has attracted increasing attention due to its potential application in separating organic–organic liquid mixtures and removing volatile organic compounds from water and soil. However, solvents like n-hexane, n-heptane and others are generally used in large amounts during its traditional preparation process. This study aimed to provide a low-pollution and high-efficiency preparation method using water as a solvent in the presence of surfactant (dodecylbenzene sulfonic acid, DBSA). Comparisons between the membranes prepared separately with the traditional method and the green method were conducted by scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (FTIR-ATR) spectroscopy and pervaporation (PV) experiments. The results showed that they performed basically the same in the first three aspects but displayed markedly different characteristics in the PV experiments. The separation factors of the PDMS membranes prepared using the green method for separating 1.5 wt% n-butanol aqueous solution at 55 °C increased by 30–53% relative to those of membranes prepared using the traditional method, while the total flux only decreased by 7–10%. These performance improvements resulted from the shortening of evaporation time induced by the decrease of n-hexane content. Further, this hypothesis was confirmed by the performance of membranes prepared using the green method, from angles of crosslinking density, water contact angle and swelling degree (SD). Comparison with previous reports on PV performance of PDMS membranes implied that the green method was not only environment-friendly and economically competitive but also led to enhanced PV performance. [ABSTRACT FROM AUTHOR]

• Adsorption and diffusion of furfural and water in vinyl-modified PDMS were simulated. • Vinyl-modified PDMS membranes were prepared based on simulation results. • 20.4% and 37.0% improvement in separation factor and furfural flux were achieved. • Experimental results were well interpreted by simulation results. Furfural is an important platform chemical for fine chemicals, which has wide applications and market prospect. However, due to the low furfural concentration in the hydrolysis product of biomass, the separation of furfural from dilute aqueous solution is energy-consuming and challenging. Herein, an efficient-energy technology, pervaporation based on vinyl-modified polydimethylsiloxane (PDMS) membrane, is suggested for the separation of furfural. To investigate the effect of vinyl group on the pervaporation performance of PDMS membrane, a molecular dynamics (MD) simulation via Materials Studio was employed, where vinyl group displays beneficial effects. Thereafter, a series of vinyl-modified PDMS membranes with different vinyl group contents were fabricated by using vinyl triethoxysilane to crosslink PDMS. The membrane exhibits a separation factor of 49.1 and a furfural flux of 737.6 g m−2 h−1 for 3.0 wt% furfural aqueous solution at 65 °C, which are improved by 20.5% and 37.2%, respectively, compared with those of the pristine PDMS membrane and conform with the expectation of MD simulation. This work proves the promising potential of MD simulation and vinyl group modification in preparing pervaporation membrane with high separation performance for furfural. [ABSTRACT FROM AUTHOR]

• Increase pore diameter and pore volume of ZIF-8 by carbonization. • Improve the diffusion process of ZIF-8/PDMS MMM by using ZNC instead of ZIF-8. • An increase of 68.7% in butanol permeability compared with ZIF-8/PDMS MMM. • The enhanced hydrophobicity is favorable for the PV performance of MMMs. • An increase of 17.6% in butanol/water selectivity compared with pure PDMS membrane. The diffusion process is the rate-limiting step for n -butanol recovery from diluted aqueous solution, which can be improved by incorporating hydrophobic nanoparticle into the polymer matrix. However, the micropore structure of zeolitic imidazolate framework-8 (ZIF-8) in the commonly applied ZIF-8-based mixed matrix membrane (MMM) could hardly meet the diffusion demand of the penetrant molecules. Herein, ZIF-8-derived nanoporous carbon (ZNC) with larger pore diameter and pore volume was prepared to replace ZIF-8 in conventional MMM in order to improve the diffusion process. An increase of 68.7% in n -butanol permeability of ZNC/PDMS MMM with 3 wt% of particle loading was obtained compared with ZIF-8/PDMS MMM. Coupled with the good compatibility between ZNC and PDMS, ZNC was homogeneously dispersed in PDMS matrix. As a result, a n -butanol permeability of 109,583 Barrer and a n -butanol/water selectivity of 4.47 were obtained for n -butanol recovery from 1.5 wt% n -butanol/water solution at 55 °C, which were increased by 145.4% and 17.6%, respectively, compared with the pure PDMS membrane. Overall, the ZNC-filled PDMS membrane shows promising in effective separation of n -butanol in realistic applications. [ABSTRACT FROM AUTHOR]

Abstract Recently, zeolitic imidazolate framework-8 (ZIF-8) has been recognized as one of the most potential doping particles for pervaporation separation of organics because of its unique pore structure and high surface area. However, in this work, ZIF-8-based mixed matrix membrane (MMM) was found to have poor stability in separating acetone-butanol-ethanol (ABE) fermentation broth due to the organic acids caused the degradation of ZIF-8 framework. To improve the stability of ZIF-8-based MMM in practical application, ZIF-8-derived nanoporous carbon (ZNC) was prepared via direct carbonization and used to replace ZIF-8 in MMM. Results indicated the acid-stability, specific surface area and pore volume of ZNC were all remarkably improved compared with those of ZIF-8. The ZNC-based MMM showed high hydrophobicity and good compatibility between particles and polymer. More attractively, during 100 h of continuous operation for ABE recovery from fermentation broth, ZNC incorporated MMM exhibited a stable performance with an average total flux of 1870 g m−2 h−1 and a n -butanol separation factor of 20. Graphical abstract Image 1 Highlights • ZIF-8-based mixed matrix membrane (MMM) has poor stability in separating ABE fermentation broth. • The degradation of ZIF-8 is affected by the organic acids. • ZIF-8-derived nanoporous carbon (ZNC) is used to replace ZIF-8 in MMM. • After incorporating ZNC into PDMS matrix, the total flux of MMM is increased significantly. • ZNC/PDMS membrane exhibits a long-time stability for ABE recovery. [ABSTRACT FROM AUTHOR]

Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient 'green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm−2h−1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of crosslinker KH571 on membrane forming were detailed evaluated. • Using PDMS-PTFPMS block copolymer not conventional PDMS to enhance membrane hydrophobicity. • Showing the ultrafast curing time within 30−50 s. • A high water contact angle >110° was obtained. • An outstanding PV performance for ethanol recovery. Crosslinker is a vital factor for the preparation of polymeric membranes, which has a substantial effect not only on the membrane-forming process, but also on the membrane structure as well as separation performance. However, little attention has been paid on UV-crosslinked membrane for organics pervaporation. In this work, the effect of crosslinker 3-methacryloxypropylmethyldimethoxysilane (KH571) on (1) the UV-crosslinking kinetics was characterized by real-time infrared spectroscopy and photo-rheology, (2) the membrane structure was characterized by crosslinking density, and (3) separation performance was evaluated by ethanol pervaporation. Moreover, the conventional polydimethylsiloxane (PDMS) was replaced by polydimethylsiloxane-poly[(3,3,3-trifluoropropyl)methylsiloxane] (PDMS-PTFPMS) block copolymer, where the strong C–F bond contributes to enhance membrane hydrophobicity. Results show an ultrafast membrane-forming process (30−50 s) for all coating solution systems and an outstanding separation performance, including 11.3 of ethanol separation factor and 1149 g m−2 h-1 of total flux for pervaporation recovery of 5 wt% ethanol/water solution at 60 °C. [ABSTRACT FROM AUTHOR]

• F-MOF incorporated PDMS MMM with high hydrophobicity was prepared. • MAF-9 provides the high transport channels for butanol molecules. • The trade-off between membrane flux and separation factor was overcome. • 24% and 16% of increases in separation factor and flux, respectively. Direct separating butanol from fermentation broth via pervaporation is considered as the most effective method to realize solvent enrichment, which is dominated by membranes. Herein, MOF (MAF-9) with CF 3 group is doped into PDMS matrix to enhance the butanol pervaporation, especially selectivity. The super-hydrophobicity of MAF-9 caused by CF 3 groups allows the preferential adsorption and permeation for butanol molecules, thus increasing the membrane selectivity; while its appropriate pore diameter renders the exquisite diffusion pathways towards the butanol molecules, thus increasing the membrane flux. Results show that the loading-optimized MAF-9/PDMS MMM has 53 of separation factor and 848 g m−2 h−1 of membrane flux, which are increased by 24% and 16%, respectively, compared with pure PDMS membrane. TGA, FT-IR, BET, and XRD are conducted to characterize the thermal stability, morphology and structure of MAF-9; PALS, SEM, AFM, SD and TGA are tested to evaluate the free volume property, morphology, adsorption capacity and thermal stability of membranes, respectively. Conditions including particle loading, feed temperature and feed concentration are also optimized in this study. [ABSTRACT FROM AUTHOR]

Large amounts of effluent discharge and a costly wastewater treatment hinder the scale-up of the lignocellulosic acetone-butanol-ethanol (ABE) fermentation process. By recycling the broth after solvents removal and using it in the subsequent cycles of biomass hydrolysis and fermentation, the overall amount of effluent can be reduced. However, the ABE production is severely inhibited by the accumulated acids and other toxic by-products when reusing the cycled streams. In this study, a pervaporation assisted sequential fermentation was performed. The ABE liquor recovered after batch fermentation and ex situ pervaporation was used as the buffer for corn stover pulp hydrolysis and the following microbial lipids fermentation. In microbial lipids fermentation stage, toxic acid by-products remained in the liquor can be co-utilized as a substrate. The acids eliminated post-harvested broth was further cycled as the buffer for pulp hydrolysis and ABE fermentation. As a result, ABE yield of 0.349 g/g and concentration of 14.40 g/L were achieved after 3 cycles of operation, which show only 3.86% and 14.98% reduction compared to those of the initial cycle. Remarkably, the effluent discharge was reduced by 92.20% after applying the hybrid two-stage sequential fermentation. Meanwhile, 8.20 g/L of microbial lipids can be co-generated. The novel process offers an environmentally friendly strategy for the co-production of ABE and microbial lipids from lignocelluloses under the concept of biorefinery. Image 1 • ABE fermentation was hybrid with ex situ pervaporation and microbial lipids fermentation. • The effluent wastewater in the hybrid process was reused by a recycled loop. • Acids by-product in the ABE fermentation broth can be used as carbon source for lipids production. • Total 3 cycles of was conducted with 92.20% of ABE wastewater saving rate. • ABE and lipids production were not obvious decreased within 3 cycles of operation. [ABSTRACT FROM AUTHOR]

The ultrashort and controllable membrane-forming process is highly required in large-scale production of PDMS membrane. To shorten the cross-linking time, an UV-induced ring-opening polymerization of the epoxide groups was introduced to the preparation of PDMS membranes. PDMS was firstly functionalized with epoxide groups, providing the possibility of being cross-linked under UV irradiation. With this strategy, the membrane curing was finished within 200 s, hence shortened by two orders of magnitude in comparison with the conventional thermal-driven method. Meanwhile, the cationic photoinitiation of epoxide groups can be achieved without oxygen inhibition in an open-air environment. Moreover, the viscosity of the coating solution in the groove is kept constant when protected from light, thus meeting the requirement of the coatability. When applied to the pervaporation of a 1.5 wt% 1-butanol/water solution at 55 °C, the measured 1-butanol separation factor was 45 and the total flux was 1119 g m−2 h−1. This novel strategy shows a great prospect in the continuous preparation of membrane. Image 1 • Introducing the UV-induced ring-opening polymerization of epoxide groups to the membrane preparation. • Shortening two orders of magnitude in the membrane-forming time. • Using the cationic photoinitiation overcomes the oxygen inhibition. • Obtaining an outstanding performance for 1-butanol recovery. [ABSTRACT FROM AUTHOR]

• CF 3 groups enhance the membrane hydrophobicity compared with conventional PDMS membrane. • A green preparation method using water as solvent is used. • The high hydrophobicity increases diffusion resistance of water molecules. • An increase of 30% in furfural/water separation factor compared with pure PDMS membrane. A high hydrophobicity of membrane plays a vital role in separating organics from dilute solution by pervaporation, which highly contributes to the increase of organics selectivity. Herein, we chose the high-hydrophobic poly[(3,3,3-trifluoropropyl)methylsiloxane] (PTFPMS) material to prepare the pervaporation membrane using a green method for the first time. Within the PTFPMS membrane, the -Si-O- chains imply the hydrophobic nature, and introducing CF 3 groups further enhances the hydrophobicity. The high-efficiency transport pathways are formed in which water will experience a larger diffusion resistance within PTFPMS membrane compared with the conventional polydimethylsiloxane (PDMS) membrane without CF 3 groups. Moreover, considering the great threat of organic solvent to the environment and operators during membrane preparation, a green approach using water instead of organic solvent was employed. Especially, when separating 1 wt% furfural aqueous solution at 80 ℃, there are 30% of increase in the furfural separation factor (45.6) and an effective increase in furfural flux (328 g m−2 h−1) compared with those of PDMS membrane. Overall, the super-hydrophobic PTFPMS membrane highly improves the feasibility of the downstream processes for recovering the biomass derives furfural. [ABSTRACT FROM AUTHOR]