Pervaporation Performance Research Articles

Tailoring the microstructure of poly(vinyl alcohol)-intercalated graphene oxide membranes for enhanced desalination performance of high-salinity water by pervaporation

Laminated graphene oxide (GO) membrane is promising in desalination owing to allowing unimpeded water permeation through the tunable interlayer nanochannels. To achieve highly efficient and stable desalination performance of GO membrane is crucial. Herein, GO membranes intercalated and cross-linked by poly(vinyl alcohol) (PVA) and supported on cellulose microfiltration membrane were fabricated via pressure-assisted filtration method for application in pervaporation desalination of high-salinity water. The interlayer spacing and microstructure of the GO membranes is successfully tailored by searching for appropriate intercalated PVA amount for cross-linking. The nanochannel microstructure was probed and its effect on the mass transport property of the membranes was revealed. The results show that the permeability of the GO-PVA membranes was dependent on both d-spacing and 3D cross-linking network between GO nanosheets. The optimized GO-PVA membranes displayed an outstanding water flux of over 98 kg/m2h and 99.99% salt rejection in desalinating 10 wt% NaCl solution at 85 °C. Benefiting from the formation of brick-mortar structure of GO layers with high adhesion strength provided by the cross-linked PVA chains with GO nanosheets, the membranes could toughly resist sonication destruction test and exhibited stable and reliable performance in pervaporation. The study helps understanding and optimizing the constitution of inner structure of intercalated GO membrane for efficient separation.

Novel fabrication of PSSAMA_Na capped silver nanoparticle embedded sodium alginate membranes for pervaporative dehydration of bioethanol.

Polystyrene-4-sulfonic acid co maleic acid sodium salt (PSSAMA_Na) capped silver nanoparticle (Ag_Np) embedded sodium alginate (Na-Alg) nanocomposite membranes have been developed to improve the pervaporation (PV) dehydration of bioethanol. The effect of PSSAMA_Na capped Ag_Nps on the micro-morphology, physicochemical properties and separation performance of the derived membranes was analyzed as a function of temperature at the azeotropic composition of the bioethanol–water mixture. WAXD analysis shows a decrease in crystalline domains with the increase in PSSAMA_Na capped Ag_Nps content and confirms the presence of Ag_Nps. DSC analysis demonstrated that the hydrophilic nature enhances as the PSSAMA_Na capped Ag_Nps content increases in the membrane matrix. Further, both total permeation flux and separation selectivity were increased with an increase in PSSAMA_Na capped Ag_Nps content. The results revealed that the membrane with 3 mass% of PSSAMA_Na capped Ag_Nps exhibited the highest permeation flux (13.40 × 10−2 kg m−2 h−1) and separation selectivity (11 406) at 30 °C which indicate its better PV performance. The total permeation flux and permeation flux of water values were close to each other, which confirms that the membranes can be efficiently used to remove the water from azeotropic aqueous bioethanol.

Supported ionic liquid membranes for the separation of methanol/dimethyl carbonate mixtures by pervaporation

Two supported ionic liquid membranes (SILM) based on 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C8MIM][NTf2]) and N-octyl-N-methylpyrrolidinium bis(triuoromethanesulfonyl)imide ([C8C1Pyrr][NTf2]) were prepared and studied for the pervaporation separation of binary mixtures of dimethyl carbonate (DMC)/methanol. Scanning electron microscope (SEM) analyses were carried out to evaluate the cross section morphology of the porous membranes before and after incorporating the ionic liquids. The pervaporation performance of SILMs was found to be highly concentration dependent. At low methanol concentration (0.2 M fraction), both SILMs tend to preferentially permeate DMC. In general, the SILM based on [C8MIM][NTf2] exhibited a better performance than the one with [C8C1Pyrr][NTf2]. Under optimal conditions, the SILM composed of [C8MIM][NTf2] enabled a transmembrane flux of 0.739 kg/m2h, a DMC/methanol selectivity of 67 and separation factor of 21 at 30 °C at 0.8 M fraction of DMC. However, at high concentration of methanol, the permeance of methanol increased due to coupling effects therefore decreasing the membrane selectivity to around 2.

Recovery of cutting oil from wastewater by pervaporation process using natural clay modified PVA membrane.

In this study, the pervaporative dehydration of the cutting oil 'diethylene glycol' (DEG) through a hydrophilic PVA membrane was investigated at various operation temperatures in the range of 333-363 K with a feed mixture containing 0.5-2.0 wt% water. The pervaporation (PV) performance of poly(vinyl alcohol) (PVA) is enhanced by the addition of natural clay kaolin into the pristine membrane. The thermal stability of the membranes was analyzed by thermal gravimetric analysis (TGA). The morphological analysis of the membranes was performed by scanning electron microscope (SEM). Separation success was determined by calculation of flux, selectivity, and PSI. These values were investigated as functions of the clay amount, feed concentration and feed temperature. The obtained results show that PV is an effective method for recycling waste cutting oil from wastewater.

Preparation of Zeolitic Imidazolate Framework-91 and its modeling for pervaporation separation of water/ethanol mixtures

Zeolitic Imidazolate Framework (ZIFs) have received much attention in recent years because of their good compatibility with polymer, and their ultramicroporosities that are in the range of the kinetic diameter of several important gas and liquid molecules. In this study, three different ZIF particles, i.e., ZIF-90 and its derivatives (ZIF-91 and ZIF-92) were synthesized and incorporated into polydimethylsiloxane (PDMS) matrix to fabricate ZIF/PDMS nanocomposite membrane for pervaporation recovery of ethanol. The morphologies and structures of ZIF particles and their nanocomposite membrane were characterized by various techniques. The results show that ZIF-91 particles with hydroxyl functional groups have good compatibility with PDMS and are dispersed well in PDMS matrix. Meanwhile, ZIF-91/PDMS nanocomposite membrane have higher pervaporation performance compared to ZIF-90/PDMS and ZIF-92/PDMS nanocomposite membrane with the same loading of 20 wt%. The effects of particle loading, feed concentration and temperature on the separation performance of ZIF-91/PDMS membranes were also investigated. The results indicate that ZIF-91/PDMS-20 wt% membrane showed a prominent separation factor of 15.8 at 55 °C with a comparable total flux of 846 g/(m2 h), which were higher than that of pure PDMS (4.1, 496 g/(m2 h)). In addition, the pervaporation modeling for the flux and separation factor of ZIF-91/PDMS membrane were established with quadratic equations of temperature and feed concentration, which can be used to predict separation performance according to the experiment conditions.

ZIF-8@GO composites incorporated polydimethylsiloxane membrane with prominent separation performance for ethanol recovery

In this study, ZIF-8@GO composites with continuous inner channels for ethanol molecules were prepared by the in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles onto the surface of graphene oxide (GO) nanosheets, and filled into polydimethylsiloxane (PDMS) matrix to fabricate PDMS/ZIF-8@GO mixed matrix membranes (MMMs) for ethanol recovery via pervaporation. The as-prepared ZIF-8@GO composites and PDMS/ZIF-8@GO MMMs were characterized by various techniques. The results showed that ZIF-8 nanoparticles were uniformly dispersed on the surface of GO nanosheets and the hydrophobicity of ZIF-8@GO composites was stronger than GO due to the surface modification of GO by hydrophobic ZIF-8. Moreover, ZIF-8@GO composites as the filler not only exhibited the excellent compatibility with PDMS but also showed the good dispersion in PDMS matrix as compared to ZIF-8 nanoparticles. Therefore, ZIF-8@GO-based MMMs showed better separation performance than ZIF-8-based MMMs. The pervaporation performance of PDMS/ZIF-8@GO MMMs was studied by adjusting the filler type, particle loading, membrane thickness, and feed temperature. The optimized PDMS/ZIF-8@GO MMMs displayed a prominent separation factor of 22.2 with a total flux of 443.8 g/m2 h with 5 wt% ethanol aqueous solution at 40 °C, and therefore the superior pervaporation performance to most other PDMS-based MMMs. The excellent pervaporation results were attributed to the synergistic effect of GO nanosheet as a strong barrier and hydrophobic ZIF-8 nanoparticles with the continuous inner channels. The synergistic effect of hybrid particles may provide valuable guidance to the development of high-performance PDMS-based MMMs for pervaporation recovery of various organic compounds.

Biphenyl-based covalent triazine framework-incorporated polydimethylsiloxane membranes with high pervaporation performance for n-butanol recovery

Biphenyl-based covalent triazine framework (CTF) particles, as a new class of organic porous materials, were incorporated into polydimethylsiloxane (PDMS) for the fabrication of a high performance pervaporation membrane for n-butanol (n-BtOH) recovery. Increasing the CTF loading remarkably enhanced both the flux and the separation factor of the membrane. This was ascribed to the strongly hydrophobic, highly porous and mesoporous structure of CTF providing highly permeable and preferential pathways for n-BtOH. Importantly, compared to other reported PDMS-based mixed matrix membranes containing conventional microporous particles, our CTF-incorporated PDMS (CTF/PDMS) membrane exhibited a significantly higher flux and excellent separation factor. Increasing feed temperature and n-BtOH concentration further enhanced pervaporation performance. As a result, the maximum n-BtOH recovery performance (total permeate flux: 2816 ± 118 g m−2 h−1, separation factor: 62.8 ± 1.5 and permeate n-BtOH concentration: 71.5 ± 2.7 wt%) was attained when the CTF/PDMS membrane containing 12.5 wt% CTF was operated with a 4 wt% n-BtOH feed solution at 60 °C. Our proposed strategy provides an effective method to prepare high performance membranes for pervaporation and gas and organic solvent separation.

Polyacrylonitrile-supported self-aggregation crosslinked poly (vinyl alcohol) pervaporation membranes for ethanol dehydration

Highly water-selective poly(vinyl alcohol) (PVA)/polyacrylonitrile (PAN) pervaporation membranes were prepared by combining self-aggregation crosslinking reactions for PVA through ammonium persulfate (APS) initiations and interface physicochemical structure regulations for PAN supports. The membrane physicochemical properties were tested and the pervaporation performances were investigated by separation of 95 wt% ethanol aqueous. The results showed that the swelling degree and crystalline region of PVA membranes decreased with the increasing of APS content. On the contrary, the gel fraction of PVA membranes increased. Interestingly, the interface physicochemical structure between the PAN support and PVA separation layer played an important role in pervaporation processes. When the PAN supports were treated by sodium hydroxide (NaOH) and tannic acid (Ta), the water fraction in permeation always kept over 99.99 wt%, especially after Ta treatment. After optimization, the membrane based on PVA content of 8 g, 1.25 g self-crosslinking agent of APS and spin-coated onto H2-PAN (PAN modified by NaOH and Ta respectively), showed good permeability-selectivity and long-term performance stabilities. The total flux and water content ratio in permeation were 117.6 g/(m2h) and 99.99 wt% respectively by using the PVA8-1.25/H2-PAN membrane. After running for 120 h, the membranes still displayed a good stability for the ethanol dehydration in the pervaporation process. Importantly, the ethanol solution could be concentrated to over 99.99% using this polyacrylonitrile-based self-aggregation crosslinked poly (vinyl alcohol) pervaporation dehydration membrane.

Incorporation of Al2O3 into cellulose triacetate membranes to enhance the performance of pervaporation for desalination of hypersaline solutions

In this study, nanocomposite membranes were prepared by incorporating alumina (Al2O3) nanoparticles into cellulose triacetate (CTA) membranes in order to enhance the performance of pervaporative desalination. The resulting membranes were characterized by SEM, TGA, water contact angle, water uptake, tensile strength, and FTIR. The desalination performance was investigated as a function of Al2O3 loading, feed temperature (ranging from 40 to 70 °C) and feed concentration (varying from 0 g/L to 90 g/L NaCl). Pervaporation (PV) experiments showed that incorporating 2% Al2O3 into a CTA membrane increased the water flux by 204% compared to pristine CTA (from 2.2 kg m−2 h−1 to 6.7 kg m−2 h−1) for a 30 g/L NaCl feed solution at 70 °C, while the salt rejection remained above 99.8%. Moreover, when the CTA-2% Al2O3 nanocomposite membrane was tested with a 90 g/L feed solution, only 25% flux reduction without sacrificing the salt rejection. Furthermore, different feed concentration affected the activation energy of water molecules to diffuse through pristine CTA and CTA/Al2O3 nanocomposite membrane. However, the nanocomposite membrane has a lower apparent activation energy even at high NaCl concentrations, compared to the pristine CTA. This suggests that the developed CTA/Al2O3 nanocomposite membrane is suitable for desalting hypersaline water.

Selective facilitated fixed-site carrier transport of methanol through sulfonated copolyimide pervaporation membranes for the separation of methanol/toluene mixtures

Dense and asymmetric membranes were obtained from novel sulfonated copolyimide synthesized by polycondensation of 3,3′,4,4′-(1,3-diphenoxybenzene) tetracarboxylic dianhydride, 4,4′-bis-diphenyl-2,2′-disulfonic acid and 4,4′-oxydianiline. The polymer was characterized by the use of NMR spectroscopy, differential scanning calorimetry, Fourier transformed infra-red spectroscopy and thermal gravimetric analysis. The morphology of the asymmetric membrane was studied with scanning electron microscopy. Pervaporation separation performance of membranes was studied for H2O/EtOH and MeOH/toluene systems at different compositions and temperatures. Transport of polar components inside the polymer matrix is discussed. The realization of the selective fixed-site carrier transport mechanism for methanol allows reaching high fluxes and separation efficiency values for mixtures with exceeding methanol content. Developed membranes showed great pervaporation performance in the case of MeOH/toluene mixtures separation by reaching a maximal separation factor value of 158 (91 wt% toluene, 20 °C, for the dense membrane with total flux of 0.007 kg⋅m−2⋅h−1) and maximal overall flux of 1.944 kg⋅m−2⋅h−1 (36 wt% toluene, 50 °C, for the asymmetric membrane with separation factor of 12).

A highly selective sorption process in POSS-g-PDMS mixed matrix membranes for ethanol recovery via pervaporation

Incorporating nanofillers into polymer matrix to construct mixed matrix membranes (MMMs) is an effective approach to improve either sorption selectivity or diffusion selectivity or both. In this contribution, octa-vinyl polyhedral oligomeric silsesquioxanes (V-POSS) particles were chemically incorporated into polydimethylsiloxane (PDMS) matrix to fabricate POSS-g-PDMS MMMs. POSS-g-PDMS MMMs exhibited a homogeneous phase and achieved good integration between V-POSS and PDMS. Compared with pure PDMS membrane, POSS-g-PDMS MMMs possessed higher crosslinking density and gel content as well as enhanced ethanol affinity and hydrophobicity, which contributed to the significant improvement of ethanol sorption selectivity with a little sacrifice of diffusion selectivity. The chemical incorporation of V-POSS into PDMS matrix significantly enhanced both separation factor and permeation flux, which showed reversal trade-off effect. The best pervaporation performance of POSS-g-PDMS MMMs was achieved at 5 wt% POSS loading, with separation factor of 17.7 and permeation flux of 536 g/(m2 h), increased by 130% and 260% compared with pure PDMS membrane, respectively. An excessive POSS loading sharply depressed the fast transport of small molecules and finally led to the decline of diffusion selectivity and separation factor. The sorption and diffusion selectivity results suggested selective sorption was a major contributor to the high separation factor of MMMs at 5 wt% POSS loading, and diffusion was a rate-controlling process. The effect of variation of external driving forces and intrinsic membrane properties induced by increasing feed temperature and ethanol concentration on pervaporation performance was also investigated in detail. This work may provide useful insights of PDMS based mixed matrix membranes, especially those with covalent bonding between organic and inorganic phases for pervaporation recovery applications.

The Ultrafast and Continuous Fabrication of a Polydimethylsiloxane Membrane by Ultraviolet-Induced Polymerization.

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.

The Ultrafast and Continuous Fabrication of a Polydimethylsiloxane Membrane by Ultraviolet‐Induced Polymerization

AbstractThe 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.

Application of PVA-b-NaY zeolite mixture membranes in pervaporation method

Abstract Pervaporation, an economical, energy-saving and eco-friendly membrane process for separating liquid mixtures, has been considered as a promising candidate for the separation of azeotropic mixtures that are difficult to separate using classical processes. In this study, isopropyl alcohol/water azeotropic mixtures were separated by the pervaporation method using poly(vinyl alcohol)-blended-NaY zeolite (PVA-b-NaY) membranes. For this purpose, different yields of PVA/NaY mixtures were prepared and characterized by using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), water contact angle and atomic force microscopy (AFM). The effect of different parameters, such as PVA/NaY yield, membrane thickness, feed solution concentration and temperature, on the pervaporation performance was examined, and the optimum conditions were determined. The best separation factor was determined to be 2690.4 at a flux of 0.00512 kg/m2.h and an IPA concentration of 87.7%. Based on the research findings, it can be said that PVA-b-NaY membranes are very effective in separating IPA and water using the pervaporation method.

Poly(vinyl alcohol)/carboxyl graphene mixed matrix membranes: High‐power ultrasonic treatment for enhanced pervaporation performance

ABSTRACTHigh‐power ultrasonic treatment was conducted during the mixing process to obtain poly(vinyl alcohol) (PVA)/carboxyl graphene (CG) mixed matrix membranes (MMMs). Results from X‐ray photoelectron spectrometer and thermogravimetric analysis confirmed the enhanced esterification reaction. The increased amorphous region and free volume were investigated by wide‐angle X‐ray diffraction and positron annihilation lifetime spectroscopy. Scanning electron microscope and atomic force microscope measurements suggested that ultrasonic could uniformly disperse CG in PVA polymer matrix. The mechanical properties and hydrophilicity of as‐prepared membrane were enhanced due to ultrasonic treatment. The permeation flux and separation factor of PVA/CG‐US membrane for 90 wt % ethanol aqueous solution were 0.79 kg m−2 h−1 and 860, respectively. For methanol (15 wt %)/methyl tert‐butyl ether mixture, its permeation flux and separation factor were also increased significantly compared with membranes without ultrasonic treatment. Due to the simplicity of the ultrasonic process and the versatility of the inorganic fillers, this method may contribute to the design of various MMMs and extend the application of these membranes in different uses. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48526.

High-hydrophobic [sbnd]CF3 groups within PTFPMS membrane for enhancing the furfural pervaporation performance

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 CF3 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 CF3 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.

High performance and thermally stable PDMS pervaporation membranes prepared using a phenyl-containing tri-functional crosslinker for n-butanol recovery

Polydimethylsiloxane (PDMS) pervaporation membranes for n-butanol recovery were fabricated using various crosslinkers: a conventional tetra-functional crosslinker and tri-functional crosslinkers containing different organic (hexyl, cyclohexyl and phenyl) groups. Irrespective of the feed solution conditions, the membranes prepared using tri-functional crosslinkers exhibited a higher permeate flux than the membrane prepared using the tetra-functional crosslinker because their less crosslinked structures increased the free volume. Importantly, among the fabricated membranes, the membrane prepared using the phenyl-containing tri-functional crosslinker exhibited the highest separation factor with a remarkably high permeate flux even under high alcohol concentration and elevated temperature conditions. Its superior pervaporation performance was attributed to its highest hydrophobicity and excellent thermal stability, which are imparted by the phenyl group in the crosslinker, combined with the tri-functional structure of the crosslinker. Our proposed strategy provides an effective and facile method to fabricate high performance pervaporation membranes for alcohol recovery.

Fast surface crosslinking ceramic hollow fiber pervaporation composite membrane with outstanding separation performance for isopropanol dehydration

A facile fast surface crosslinking method was adopted to fabricate ceramic hollow fiber composite membranes with a thin separation layer for outstanding pervaporation (PV) performance. The morphologies, surface chemical compositions and hydrophilicity of the chitosan (CS)/ceramic hollow fiber composite membranes were characterized by field emission scanning electron microscopy (SEM), X-ray photoelectron analysis (XPS), and water contact angle (CA), respectively. The influences of CS concentration, feed composition and temperature on the membrane performances were investigated systematically. The operation time of the surface crosslinking process was several minutes (i.e., 4 min). The thickness of the separation layer of the obtained composite membranes ranged from 322 to 1414 nm, exhibiting excellent separation performance. The Arrhenius active energy (EJ and ED) and the diffusion coefficient (Dw and DIPA) were calculated to theoretically analyze the membrane separation process. The highest PV separation index (PSI) value was 8.2 × 106, indicating that the obtained membranes possessed enormous potential in IPA dehydration.

HCl modification and pervaporation performance of BTESE membrane for the dehydration of acetic acid/water mixture

Membrane pervaporation has gained much attraction for high level purity of acetic acid from water because of energy saving and ecofriendly operation compared with distillation and extraction. However, fabricating membranes with high stability, selectivity and permeation flux for dehydration of acetic acid by pervaporation is highly demanded. In this work, hybrid silica membranes were fabricated using bis(triethoxysilyl) ethane (BTESE) as a precursor through sol gel route. Further modification was done as solid post HCl treatment for the synthesized BTESE membrane aiming to improve separation performance of the BTESE membranes for dehydration of acetic acid. The effect of HCl exposure time (30, 100, and 150 min) to the synthesized BTESE membranes was investigated to get optimum treatment conditions with lower separation tradeoff. In our investigation HCl treatment for about 100 min was found suitable in order to maintain permeation flux with higher selectivity. For the pervaporation performance to dehydrate acetic acid/water (90/10 wt%) at 80 °C, the synthesized BTESE membrane showed total flux of 2.47 kg m−2 h−1 with separation factor about 350 but HCl treated (100 min) BTESE membrane showed almost double separation factor up to 780 with somehow reduced flux (2.07 kg m−2 h−1). Both the membranes (synthesized and HCl treated BTESE) showed good stability within the investigated time of 150 h at 80 °C.

Graphene oxide membranes with fixed interlayer distance via dual crosslinkers for efficient liquid molecular separations

The interlayer distance of stacked graphene oxide (GO) membranes is the decisive factor of achieving high permeability and selectivity. Fixating the size of 2D channel in GO membrane proves a critical challenge for liquid separation. Herein, GO membrane was firstly crosslinked by polyvinylamine (PVAm) to acquire mechanically stable membrane, and PVAm then induced the biomimetic mineralization to in situ generate silica as the second crosslinker to further fixate the size of 2D channels. The interlayer distance of GO-PVAm-Silica membrane fixed around 0.62 nm in water, showing the improved swelling resistance compared to the GO-PVAm membrane. The resultant GO-PVAm-Silica membrane featured high water permeability as well as distinct sieving properties for bio-alcohol molecules and hydrated ions. To be specific, the membrane exhibited a superior pervaporative dehydration performance with separation factor of 1188 ± 39 and flux of 12.9 ± 0.3 kg/(m2h) under 80 °C for 90 wt% butanol/water mixture. And the membrane showed a high NaCl rejection rate of higher than 99.99% and total permeation flux of 80.2 ± 0.8 kg/(m2h) when treating 3.5 wt% NaCl solution under 70 °C. Moreover, the GO-PVAm-Silica membrane kept excellent operation stability in 168 h test.