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Abstract: Membrane separation, a new technology for removing VOCs including pervaporation, vapor permeation, membrane contactor, and membrane bioreactor was presented. Comparing with traditional techniques, these special techniques are an efficient and energy-saving technology. Vapor permeation can be applied to recovery of organic solvents from exhaust streams. Membrane contactor could be used for removing or recovering VOCs from air or wastewater. Pervaporation and vapor permeation are viable methods for removing VOCs from wastewater to yield a VOC concentrate which could either be destroyed by conventional means, or be recycled for reuse. [ABSTRACT FROM AUTHOR]

Hydrophilic polymers have garnered much attention due to their critical roles in various applications such as molecular separation membranes, bio-interfaces, and surface engineering. However, a long-standing problem is that their mechanical properties usually deteriorate at high relative humidity (RH). Through the simultaneous incorporation of functionalized carbon nanotubes and copper ions (Cu2+), this study introduces a facile method to fabricate high strength polyelectrolyte complex nanohybrid membranes resistant to high RH (90%). For example, the tensile strength of the nanohybrid membranes is 55 MPa at 90% RH (80% of the original value at 30% RH). These results are explained by copper ions depressing the swelling degree of the membrane, and functionalized carbon nanotubes promoting stress transfer between the polymer matrix and them. The nanohybrid membranes are efficient in separating water/alcohol mixtures containing relatively high water content (up to 30 wt%), whereas common hydrophilic polymer membranes usually suffer from excessive swelling under this condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PEI-Im-CTG CEMs were modified via Debus-Radziszewski in-situ crosslinking. • The PEI-Im layer had rigid structure and strong cation-surface interaction. • The PEI-Im-CTG membrane exhibited high permselectivity between Li+ and Mg2+. • The PEI-Im-CTG membrane showed a high Li+ purity during two-stage ED process. Lithium extraction from salt-lakes is a crucial way to solve the global shortage of lithium resources. With high sustainability and efficient ion separation, electrodialysis (ED) has a high potential for lithium extraction from salt-lakes, yet suffering from the challenges of cation-cation selectivity. In this work, a facile Debus-Radziszewski in-situ cross-linking approach was proposed to construct a polyethyleneimine modification layer containing imidazole groups (PEI-Im) on a common cation exchange membrane (commercial membrane, i.e., CTG membrane) surface to enhance the lithium selectivity. The pore size, architecture rigidity and charged characteristic of this PEI-Im layer were controlled via adjusting the reaction conditions. The resultant membrane (PEI-Im-CTG) exhibited high Li+ permeation rate (0.89 mol·m−2·h−1) and excellent Li+/Mg2+ permselectivity (13.1), which are 4.0 times and 19.8 times higher than that of the pristine CTG membrane, respectively. Moreover, the PEI-Im-CTG membrane based two-stage ED process showed a high Li+ purity (∼99.90 %) and low energy consumption (∼0.158 kWh·mol-1Li+) for Li+ extraction from simulated salt-lakes. This work offers a facile and effective strategy for membrane modification with high Li+ selectivity, which is promising in lithium extraction from salt-lakes. [ABSTRACT FROM AUTHOR]

Antifouling is important for RO membranes. Taking advantage of the reaction between hydroxyl groups on zwitterionic colloid nanoparticles (ZCPs) and acyl chloride group, ZCPs with tuned chemical structures were added into m -phenylenediamine aqueous solution to prepare thin-film nanocomposite membranes (ZPMs) via interfacial polymerization in this study. The incorporation of ZCPs tailored the membrane surface morphology and chemical properties, which were characterized by SEM, AFM, WCA, FTIR and XPS. Meanwhile, the effect on RO membranes separation and antifouling performances were systematically evaluated. In comparison with pristine membranes, the values of WCA decreased which means the hydrophilicity of membranes surface enhanced due to the existence of ZCPs, endowing the membrane with advanced water flux (37.3 L·m − 2 ·h − 1 ) when operate with 2000 ppm NaCl aqueous solution at 25 °C under 1.5 MPa. In order to evaluate the antifouling properties, the filtration with different types of model foulants were operated. When feed solution containing tannic acid, sodium alginate or sodium dodecyl sulfonate respectively as model foulants, ZPMs exhibited low water flux reduction and high water flux recovery after cleaning due to increased hydrophilicity and surface smoothness. Therefore, the ZPMs with improved separation and antifouling performances are promising candidates for practical application in brackish water desalination. [ABSTRACT FROM AUTHOR]

High strength polyelectrolyte complex (PEC) nanocomposite membranes were prepared via synergistic ionic complexation between graphene oxide/carbon nanotubes nanofillers (GO/CNT) and oppositely charged polyelectrolytes of sodium carboxymethyl cellulose (CMC) and poly(2-methacryloyloxy ethyl trimethylammonium chloride) (PDMC). Ultraviolet-visible, Raman spectroscopy and microscopies results demonstrated that the combination of one-dimensional CNTs and two-dimensional GO nanosheets lead to an integrated three-dimensional network through π-π interaction with GO distributed parallel to the surface of PEC membranes. Besides, CNTs and GO nanosheets are tightly encapsulated by PEC matrix through electrostatic interactions. The tensile strength of PEC/GO-CNT nanocomposite membrane containing 3 wt% GO-CNT (1:1, w/w) was 155.4 MPa, showing 2.3 and 1.6 times as high as that of PEC/CNT and PEC/GO membranes, respectively. Moreover, PEC/GO-CNT membranes showed improved separation performance and operation stability with introduction of the three-dimensional network constructed by GO and CNT. [ABSTRACT FROM AUTHOR]

Sugar dissolved in solution is found to stabilize native structure of proteins and notably decrease their denaturation. To better utilization of this unique performance, we herein studied the preparation and application of a novel isoporous membrane with dual sugar and temperature responsiveness that offered both decreased protein denaturation and improved separation efficiency. New block copolymers (BCPs) with poly (N-isopropyl acrylamide-co-acrylamidophenyl boronic acid) P(NIPAM- co -APBA) as pore forming blocks were synthesized and adopted to prepare isoporous membranes via the SNIPS method. The boronic acid moieties in P(NIPAM- co -APBA) were found to endow membranes with adoptive changes of pore size with the variation of sugar concentrations. The microphase separation of BCPs in concentrated solutions and thin film were carefully studied, observing that APBA attached to pore-forming segment greatly increased the phase separation strength for BCPs. Composition analysis indicated that membranes with uniform pore structures showing higher contents of APBA groups on surface, uncovering an interesting structure-composition relationship that segments with higher fractions of APBA moieties segregated much stronger to pores and surface. Sugar dependent permeability and protein sieving were also determined, observing that the separation coefficient increased sharply from 4.2 to 11 for protein mixture of Hemoglobin/Lysozyme, suggesting that prepared isoporous membranes had enabled a faster separation of proteins in the presence of sugars. It was finally found that sugar in solution simultaneously reduced membrane fouling as it decreased protein denaturation during the separation. Our results demonstrate that novel isoporous membranes fabricated from bio-responsive BCPs with specifically designed functionality will enable protein separation with reduced denaturation, decreased membrane fouling and higher separation selectivity, which remain a big challenge for traditional isoporous membranes produced from well-explored BCPs. [Display omitted] • Molecular level design of novel BCPs bearing boronic moiety as pore forming were described. • Isoporous membranes with uniform pore size were successfully prepared from above BCPs. • Stronger microphase separation was observed for membranes produced from BCPs with higher contents of boronic groups. • Sugar and temperature dependent permeability and protein sieving was fully studied. • Protein denaturation and fouling was obviously reduced by the glucose guided separation. [ABSTRACT FROM AUTHOR]

Polyamide (PA) thin film nanocomposite (TFN) reverse osmosis (RO) membranes have been vigorously developed, which could be used in saline water desalination, wastewater treatment and chemicals separation and purification. Aiming at further improving the TFN RO membrane comprehensive performances, such as the perm-selectivity, stability and anti-fouling/-microbial properties remains a great challenge. Herein, we proposed a biomimetic nanoparticle redox strategy to in-situ integration of multiple functional nanoparticles, i.e., biomimetic nanoparticles (BNPs) and silver (Ag) nanoparticles into the PA matrix for simultaneously regulating the membrane microstructure and optimizing the surface property. A much hydrophilic selective layer with interior transporting channel structure renders the resultant RO membrane PA-BNP-Ag with an enhanced water permeance of ∼4.2 L m−2·h−1bar−1 without sacrificing NaCl rejection (∼98.1%). The BNPs induce Ag nanoparticles uniformly distributed within the PA matrix, which significantly improves the membrane anti-fouling/-bacterial property. The water flux recovery ratio of PAM-BNP-Ag was improved to be higher than 96% during several cycles filtration of saline solution containing bovine serum albumin foulants. More importantly, the membrane sterilization rate against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) achieves nearly 100%. This work provides a new strategy for the construction of advanced PA TFN membranes with both high perm-selectivity and anti-fouling/-microbial property in RO desalination. [Display omitted] • The TFN RO membrane was fabricated with in-situ integration of multiple functional nanoparticles. • The TFN RO membrane with high hydrophilic surface and tunable microstructure. • The TFN RO membrane exhibits both high water permeance and NaCl rejection. • The TFN RO membrane represents excellent anti-fouling/-bacterial property. [ABSTRACT FROM AUTHOR]

Polysaccharide nanofiltration (NF) membrane with traditional modification normally suffers from poor water permeability as a result of its tight packing of polymeric chains. In this work, a novel membrane building block, polyelectrolyte complex (PEC) nanoparticles (NPs) armed with adjustable content of sulfated groups was developed using chitosan and dextran sulfate sodium. The sulfated polyelectrolyte complex membranes (SPECMs) were first prepared by solution-casting and glutaraldehyde crosslinking process, and their structural characteristics and surface properties were systematically investigated. Intrinsic aggregation structure combined with numerous sulfate groups attenuates packing density of polymeric chains and promotes hydrophilicity, endowing SPECMs with high flux and perm-selectivity. SPECMs achieved a water permeability of 6.71 L m −2 h −1 bar −1 , which was ∼2.3 times higher than pristine sulfated chitosan membrane. The selectivity for NaCl/Na 2 SO 4 separation and NaCl/methyl blue dye separation were as high as 13.1 and 850.0, respectively. Moreover, SPECMs featured efficient dye antifouling property with low flux decline ratio (6.8%) and high recovery ratio (96.8%), which was primarily attributed to its hydrophilicity and smooth surface. The prominent perm-selectivity associated with antifouling property suitably position SPECMs for practical small organic molecule/inorganic salt mixture separation in a long-term process. [ABSTRACT FROM AUTHOR]

Zwitterionic monomers have aroused great attraction for membrane preparation due to their tremendous hydrophilicity and antifouling properties. Zwitterionic diamine monomer N-aminoethyl piperazine propane sulfonate (AEPPS) was added into m -phenylenediamine (MPD) aqueous solution to react with trimesoyl chloride (TMC) via interfacial polymerization to fabricate zwitterionic thin film composite reverse osmosis membrane (TFCMZs). The membrane preparation conditions, including AEPPS content, TMC concentration and curing temperature, were systematically evaluated. The membrane surface hydrophilicity and antifouling properties of TFCMZs were greatly enhanced via introducing AEPPS into membranes. When tested with brackish water desalination conditions (2000 ppm NaCl feed solution at 1.5 MPa and 25 °C), the water flux of TFCMZs containing 10% AEPPS was significantly increased to be 54.5 ± 3.2 L·m − 2 ·h − 1 , which is about an 82% increase compared with the pristine membrane, while the NaCl rejection remains above 98%. Furthermore, using tannic acid (TA) and sodium alginate (NaAlg) as model foulants, the TFCMZs displayed outstanding fouling-resistant and easy-cleaning properties. TFCMZs present both admirable separation and fouling-resistance performance, which indicates that TFCMZs have wide application potential for brackish water desalination. [ABSTRACT FROM AUTHOR]

Nanomaterials are widely used to improve the separation performance for asymmetric isoporous membranes. Different from those prevalent researches, MOFs crystals with particle sizes of 0.52–0.75 μm which were an order magnitude larger than the molecular size of block copolymers (BCPs) were loaded to casting solution, and their tailoring on membrane formation and permselectivity of isoporous membranes prepared via the SNIPS were carefully investigated. As far as we know, 3D particles with such big size have never been added to isoporous membranes before. Results from small angle X-ray scattering indicated that the microphase separation in solutions had been increased obviously although MOFs crystals were too large to co-assemble with BCPs. This interesting finding was assigned to the breathing effect from MOFs crystals that increased the effective concentrations of BCPs. Morphology observation indicated that MOFs crystals located on surface were fully covered by a thin layer of BCPs which also assembled into defect-free, isoporous structures. This result was observed even though the contents of MOFs in membranes reached 40 wt%. It was measured that the permeability and selectivity to protein mixtures improved obviously by the MOFs crystals blended to membranes. Finally, with the removal of MOFs from membranes by acid etching, the permselectivity of membranes improved further. Considering the easy synthesis and good dispersibility, micro-sized MOFs crystals can be used as more effective additives to improve the separation performances for isoporous membranes than that of nanomaterials. This finding will pave the ways for preparing the high-performance isoporous membranes by using MOFs crystals as the additives for block copolymers. [Display omitted] • Defect-free isoporous membranes are successfully prepared with MOFs loadings up to 40 wt%. • The microphase separation and domain size have increased obviously by the MOFs. • The solvent adsorption and breathing effect from MOFs account for higher permselectivity. • Performance of membranes prepared with MOFs of different sizes and properties are compared. • The permselectivity of membranes is further improved when the MOFs are etched. [ABSTRACT FROM AUTHOR]

A polyacrylonitrile/palygorskite composite chemically modified with amidoxime groups was prepared by free-radical graft polymerization of acrylonitrile onto 3-glycidyloxypropyl trimethoxy silane (KH-560)-modified palygorskite and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Adsorption of uranium(VI) from simulated seawater on the material was investigated. Batch experiments were carried out to study the effects of initial pH, contact time, initial feed concentration and ionic strength on uranium removal. The solution pH values had a major impact on uranium(VI) adsorption with optimal adsorption observed around pH 5. The kinetic data followed the pseudo second-order process. The equilibrium data fitted the Freundlich model well and the maximum adsorption capacity was found to be 78.13 mg/g. The ionic strength did not significantly affect uranium removal and chemisorption was assumed to describe the uranium adsorption. Desorption was performed using 0.1 M HCl solution, and the regenerated adsorbents could be reused with little loss of adsorption capacity after five cycles. [ABSTRACT FROM AUTHOR]

The mesoporous silica SBA-15 with short channels was prepared and added into the solution of polyvinyl chloride (PVC) to form the SBA-15-PVC membrane via the phase-inversion process. Under the optimized preparation conditions with 5 (wt%) of SBA-15 and 10 (wt%) of PVC, the adsorption capacity of uranium(VI) can reach 2,519.8 mg/m at pH 6. Nine repeated adsorption-desorption cycles were carried out, and the adsorption capacity is almost kept the same in the last eight cycles. Therefore, SBA-15-PVC membrane could be as a promising adsorbent for uranium(VI) from aqueous solutions with large adsorption capacity and reusability. [ABSTRACT FROM AUTHOR]

Abstract: Functionalized multiwalled carbon nanotubes (MWNTs) were incorporated into a chitosan membrane for separation of benzene/cyclohexane mixtures by pervaporation. The pristine MWNTs were treated by mixed acid (H2SO4/HNO3=3/1) and then functionalized with isonicotinic acid. Ag+ was grafted to the pyridine ring on the MWNTs by a complexation reaction. Membranes made of chitosan and Ag+/carbon nanotubes were prepared with polysulfone membranes as support. The surface structure of modified MWNTs was examined by FT-IR, TEM, EDS and XPS to assess its morphology. The swelling and pervaporation characteristics of the membranes for separation of benzene/cyclohexane mixtures were investigated. The swelling degree of the membranes in benzene was more than 2.5 times that of the pristine chitosan membrane. The swelling degree was found to increase with the content of the MWNTs–Ag+ in the membrane and the benzene content in the feed. Pervaporation results also showed that the MWNTs–Ag+/chitosan hybrid membrane separation performance is better than MWNTs/chitosan hybrid membrane and pristine chitosan membrane. The permeation flux of the membrane increased, the selectivity increased firstly and then decreased with the increase in the content of MWNTs–Ag+. The selectivity reached 7.89 and the permeate flux was 357.96g/m2 h (the mass ratio of benzene was 50%, the temperature was 20°C) when the percentage by weight of the MWNTs–Ag+ to chitosan was 1.5%. The Arrhenius activation parameter of 1.5% MWNTs–Ag+/chitosan (CS) hybrid membrane is 4.28kJ/mol while 1.5% MWNTs/CS membrane is 10.6kJ/mol in 50% benzene concentration in feed. [Copyright &y& Elsevier]

Highlights: [•] Silica modified with polyelectrolyte was synthesized. [•] Membranes were prepared incorporation of modified silica. [•] Membranes demonstrate enhanced mechanical property and separation performance. [ABSTRACT FROM AUTHOR]