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The separation of magnesium and lithium is the key issue of preparation of pure lithium product due to their similar chemical property. Thermodynamic analysis was conducted on the removal of magnesium from lithium chloride solutions with phosphate precipitation method. The thermodynamic equilibrium diagrams of Mg 2 + - PO 4 3 - - H 2 O, Li + - Mg 2 + - PO 4 3 - - H 2 O and Li + - Mg 2 + - NH 4 + - PO 4 3 - - H 2 O systems at 298 K were established, separately. The effect of process parameters on the removal of magnesium was also investigated. The results revealed that the existence of Li + was not beneficial to the removal of magnesium, and the precipitation method of MgNH 4 PO 4 performed better than that of Mg 3 (PO 4 ) 2 for the separation of magnesium from lithium chloride solutions. The equilibrium concentration of magnesium decreased with the increase in total concentration of NH 4 + and the decrease in concentration of Li + . With the precipitation method of MgNH 4 PO 4 , there are four regions of stable solid phase in the pH range of 4.5–13.0 in lithium chloride solutions containing 1 mol/L Li + , 0.03 mol/L NH 4 + , 0.01 mol/L Mg 2 + and 0.03 mol/L PO 4 3 - , which are MgHPO 4 (5.9 < pH < 6.6), MgNH 4 PO 4 (6.6 < pH < 9.6), Mg(OH) 2 (10.0 < pH < 13.0) and Li 3 PO 4 (6.6 < pH < 1.3), respectively. The verification experiment results showed that the concentration of magnesium can be reduced to 0.011 g/L from a feed solution containing 14.95 g/L (∼1 mol/L) Li 2 O and 0.45 g/L (∼0.02 mol/L) Mg 2+ by adding 0.025 mol/L ( NH 4 ) 3 PO 4 · 3 H 2 O at pH 8 and 25 °C, while the concentration of residual phosphorus in purified solution was only 0.004 g/L, which was consistent with the thermodynamic analysis. [ABSTRACT FROM AUTHOR]

Abstract: Pretreatment to reverse osmosis (RO) seawater desalination historically has been achieved using organic (polymer) ultra- and micro-filter (UF/MF) membranes. Newly developed inorganic (ceramic) membranes offer unique advantages over the currently employed membranes, and were recently introduced for the purpose. In this work, we investigate the performance of a zirconium dioxide ceramic membrane with 0.05μm pore diameter to clarify raw seawater under different operating conditions. The influences of cross-flow velocity (2.7–4.9ms−1), temperature (15–55°C), transmembrane pressure (TMP) 0.1–0.2MPa, and seawater pH (5.5–9.5) on permeate flux and rejection were assessed. The results show that the zirconium dioxide membrane at cross-flow velocity of 3.7–4.2ms−1, TMP of 0.14–0.18MPa, temperature of 25–30°C and seawater pH of 8.0–9.0 exhibited a high flux of 420–450Lm−2 h−1 with turbidity and CODMn rejection of 99.0–99.5% and 32–35%, respectively. This work also introduces a new experimental procedure to determine different filtration resistance (R m, R sads, R pads, R cp, R pb and R cr) components, which helps the analysis of performance characteristics and the better understanding of interactions between the membrane and foulants. The present results show that the effect of concentration polarization was dominant in the ultrafiltration of raw seawater, and various fouling components contribute to the total in the order of R cp > R sr > R m > R sads > R pads > R irr. Further, reversible fouling was much more significant than irreversible fouling. The experimental method also showed interrelation between the reversible and irreversible resistances, whereby part of R sr is transformed into R irr within 20min of filtration. The results of this study indicate that zirconium dioxide ultrafiltration pretreatment before RO desalination can achieve consistent permeate quality and low fouling potential at high permeate fluxes. [Copyright &y& Elsevier]

Abstract: Interfacially polymerized polyamide thin film composite membrane was modified by electrostatic self-assembly of polyethyleneimine on the membrane surface, and the modified membrane showed significantly improved antifouling properties. The charge reversal on the membrane surface due to the application of the polyethyleneimine layer was shown to increase the fouling resistance of the membrane to cationic foulants because of the enhanced electrostatic repulsion, and the increased surface hydrophilicity would help minimize the flux reduction. The effects of parameters involved in the membrane surface modification (e.g., polyethyleneimine concentration and deposition time) on the membrane performance were investigated in terms of water permeation flux and salt rejection. The membrane modification was found to increase salt rejections when MgCl2 and NaCl were tested. The fouling behavior of the membranes was also studied with and without the presence of dodecyltrimethylammonium bromide (which is a common cationic surfactant present in waste water). It was shown that while the deposited polyethyleneimine surface layer tended to offer additional resistance to permeation, the improved fouling resistance and the increased surface hydrophilicity compensated for the reduction in membrane permeability due to the deposition of the polyethyleneimine layer. [Copyright &y& Elsevier]

[Display omitted] • DETA/TA cross-linked polymeric substrate was first used to fabricate dense MOF membrane. • TA and DETA provided enough heterogeneous sites for preparing dense MOF membrane. • DETA anchored TA molecules on hollow fiber substrate to form tight spatial network. • Structure stability of membrane was enhanced by the synergistic effect between TA and DETA. • TA-DETA-PVDF/ZIF-8 composite membrane showed considerable gas separation performance. In this work, a continuous dense zeolite imidazolate framework (ZIF) composite membranes for enhanced gas separation were successfully prepared on diethylenetriamine (DETA) and tannic acid (TA) cross-linked polymeric hollow fiber substrates via the in-situ solvothermal method for the first time. With strong reactivity and small molecular volume, DETA connected various TA molecules and anchored TA molecules on the organic hollow fiber substrate to form a relatively tight spatial network. The modified polyvinylidene fluoride(PVDF) support contained abundant phenolic hydroxyl, carbonyl, and amine groups, providing a large number of active sites for heterogeneous nucleation and promoting the forming of continuous and non-defect MOF film. The synergistic effect between TA and DETA not only enhanced the stiffness and durability of the MOF composite membrane, but also improved the performance of membrane on gas separation. The morphology of the amine/TA modified to support and the MOFs composite membrane was analyzed by SEM, XRD, FTIR, XPS, etc. The fabricated TA-DETA-PVDF/ZIF-8 composite membrane with a continuously dense layer and unique structural stability displayed excellent H 2 permeance of 1.01 × 10-7 mol·m−2 s−1 Pa−1 and competitive H 2 /N 2 and H 2 /CH 4 selectivity of 24.0 and 24.4, respectively. [ABSTRACT FROM AUTHOR]

PEI/ZIF TFC total heat exchange membranes (THEMs) with enhanced energy recovery and CO 2 barrier properties were formed by in situ grown ZIL-L micro crystalline leaves from the PEI matrix. PEI sealing could effectively open up internal pores of ZIF-L particles while shapes of ZIF-L could be tuned further for better THEM performance. [Display omitted] • PEI chains could tightly seal a mass of ZIF-L on PSF substrates. • PEI sealing could effectively open up internal pores of ZIF-L particles. • Large masses of ZIF-L particles were well dispersed in the PEI matrix. • Shapes of ZIF-L could be tuned for better THEM performance. • THEMs with higher energy recovery and CO 2 barrier properties were formed. A novel strategy was developed to build high-performance thin film composite (TFC) total heat exchange membranes (THEMs) by in situ growing ZIF-8 crystalline micro-leaves (ZIF-L) from Polyethyleneimine (PEI) coated on polysulfone (PSF) ultra-filtration substrates. It was found that flexible PEI polymeric chains could tightly cross-link and seal large masses of ZIF-L micro-leaves (ZIF/PEI wt. ratio up to 18.5) to thwart CO 2 permeation, on top of PSF substrate. Such PEI cross-linking could also effectively open up the internal channels of ZIF-L micro-leaves to enhance moisture permeance and latent heat recovery without trading off CO 2 gas barring property. ZIF-L in varied shapes protruded into the air stream could provide ultra-rough surfaces with increased surface area for improved total energy recovery efficiency. Optimized PEI/ZIF-L TFC THEMs showed ultra-low CO 2 permeance of 0.5–8 GPU and ultra-high total heat recovery rates of 68–74%. [ABSTRACT FROM AUTHOR]

• The membrane prepare by using 2-chloro-1-methyl iodopyridine as an active agent to graft a cationic macromolecule polymer (PEI) onto the membrane surface. • This film exhibits a higher removal rate for toxic metal ions and polyvalent cation salts and dyes. • Polyethylenimine(PEI) with carboxylic acid and acyl chloride to form covalent bonds on the membrane surface. The performance of nanofiltraton (NF) membranes are characterized by a high selectivity for multivalent anions, whereas poor selective separation capacity for multivalent cations and heavy metal ions. In this work, a new positively charged NF membrane was prepared by using 2-chloro-1-methyliodopyridine as an active agent to graft polyimide polymer onto the membrane surface via covalent bonding with surface carboxylic groups. The results showed that the prepared membranes had a high selective separation for divalent and monovalent salts (MgCl 2 97.1%, CaCl 2 96.8%, Na 2 SO 4 83.5%, MgSO 4 87.3%, NaCl 49%, LiCl 32%), and also exhibited a high removal efficiency for toxic heavy metal ions and dyes (CuCl 2 96%, NiCl 2 95.8%, CrCl 3 98.0%, Tropaeolin O 98.3%, Victoria blue B 99.2%, Semixylenol orange 99%, Neutral 98.2%). [ABSTRACT FROM AUTHOR]

Highlights • GO dispersions do have good antimicrobial activity. • GO nanosheets lost their antimicrobial activity once they were assembled into GO membranes. • Layered GO membranes exhibit excellent stability in a 14-day test. • Antifouling properties of GO membranes need to be improved. Abstract GO is of great interesting for membrane materials due to its unique properties including antimicrobial activity and antifouling property. However, the differences between GO nanosheets and layered GO membranes gained little attention. Herein, we fabricated GO membranes that have a thickness of around 30 nm and a void d-spacing of 0.67 nm (wet state) with single layer GO nanosheets of 10–75 nm in lateral size and investigated their antimicrobial and antifouling potential for practical use. It exhibits typical nanofiltration performance, with the rejections of 65.23%, 17.79%, 42.10% and 12.47% to Na 2 SO 4 , NaCl, Mg 2 SO 4 and MgCl 2 , respectively. The antimicrobial test demonstrated that GO nanosheets lose their antimicrobial activity after they stacked together. A 14-day test showing that GO membrane has excellent resistance for organic fouling, with reversible fouling of more than 98%. But when it comes to tapwater, the proportion of irreversible fouling is surging to more than fifty percent even after cleaning with 2000 mg/L of sodium hypochlorite. Thus, we suggested that there are more details should be investigated before put layered GO membrane into practical use. Surprisingly, GO membrane exhibits excellent mechanical stability during the 14-day test, showing its exciting potential in water treatment. [ABSTRACT FROM AUTHOR]

Highlights • A monovalent selective cation exchange membrane was assembled in MCDI system (MSCDI) to separate lithium from magnesium. • MSCDI shows excellent separation effect of magnesium and lithium, with a low energy consumption. • A custom-made large module was adopted for the selective removal of lithium. Abstract Membrane capacitive deionization (MCDI) is an effective water purification technology. In this work, a monovalent selective cation exchange membrane (CIMS) was assembled in MCDI system (denoted as MSCDI) to separate lithium from magnesium. The effects of feed water quality and operating conditions on the lithium removal selectivity were systematically investigated. Specifically, in optimized conditions, the lithium selectivity coefficient reached 2.95. Furthermore, a custom-made large MSCDI module was applied to the selective removal of lithium. The removal rates of Li+ and Mg2+ in large module reached 38.4% and 19.2%, respectively. It is worth noting that the specific energy consumption was 0.0018 kWh mol−1, which is much lower than that of electrodialysis (0.04–0.27 kWh mol−1). Therefore, relying on its low energy consumption and environmental friendliness, MSCDI has considerable economic benefits for the efficient lithium extraction. [ABSTRACT FROM AUTHOR]

Highlights • Hydrophilic MPEG brushes were grafted onto the surface of PA TFC RO membrane. • Membrane performance in tertiary treatment of textile effluent was investigated. • Membrane water permeability and fouling resistance to textile effluent were improved. • Membrane COD removal and conductivity rejection to textile effluent were enhanced. • Membrane durability against chlorine was also improved. Abstract To improve the separation performance and durability of the aromatic polyamide thin-film composite reverse osmosis membrane in tertiary treatment of textile effluent, grafting of hydrophilic polymer brushes was performed in this work through sequential surface treatment using acidic aqueous glutaraldehyde and monomethoxy-poly(ethylene glycol) (MPEG) solutions. ATR-FTIR and XPS analyses confirmed that MPEG brushes were grafted on membrane surface at the sites of N H group of amide linkages and end amino groups in the polyamide active layer. The modification was found to enhance membrane fouling resistance, water permeability and rejections to both COD and conductivity in tertiary treatment of textile effluent. The steady-state flux of the modified membrane to secondary textile effluent was higher by 24.0% compared with the virgin membrane and comparable with that of the commercial membrane BW30FR. The grafting of MPEG brushes was also found to make the membrane less susceptible to chlorine. After ten times of intensified chlorine exposure, i.e. total chlorine exposure of 42,000 ppmh NaClO of 35.0 °C and pH 9.0, the membrane grafted with MPEG brushes maintained COD and conductivity rejections of 97.9% and 98.5%, respectively, to textile effluent, showing better durability against chlorine than the virgin membrane and compared membrane BW30FR. [ABSTRACT FROM AUTHOR]

Highlights • A surface hydroxylation process for SBA-15 with short channels was investigated. • NaOH solution of low concentration was employed for the hydroxylation of SBA-15. • Hydroxylated SBA-15 showed a 20.8% increase in surface silanol groups. • AO-functionalized hydroxylated SBA-15 has higher AO amount than unhydroxylated one. • The U(VI) adsorption capacity on pristine AO-hydroxylated SBA-15 was 709 mg g−1. Abstract A surface hydroxylation process with an alkali solution of low concentration was employed to recover surface silanol groups of SBA-15 prior to amidoxime (AO)-functionalization. The effect of concentration and temperature on surface hydroxylation were investigated, and the optimal conditions of 0.003 mol L−1 and 65 °C for the surface hydroxylation were determined. The silanol density was increased from 1.20 mmol g−1 of the untreated SBA-15 to 1.45 mmol g−1 of the hydroxylated SBA-15. Characterizations through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N 2 adsorption-desorption proved that the hydroxylation process did not destroy mesopore structure and morphology of SBA-15. The hydroxylated SBA-15 could anchor more AO groups than the untreated SBA-15, resulting in higher U(VI) adsorption capacity (709 mg g−1) of the pristine AO-functionalized SBA-15 following hydroxylation than that of untreated sample (601 mg g−1). The adsorption capacity of the regenerated samples slightly decreased after three sorption-desorption cycles. Compared with other coexisting cations (Na+, K+, Mg2+, and Ca2+) in artificial seawater with rich uranium, the distribution coefficient (K d) and concentration factor (CF) value of UO 2 2+ were far larger, suggesting high selectivity of AO-H-SBA-15 for UO 2 2+. These results indicate that the surface hydroxylation process can enhance U(VI) adsorption maintaining the high adsorption selectivity and long-term adsorption stability. [ABSTRACT FROM AUTHOR]

Graphical abstract A durable and antifouling monovalent selective anion exchange membrane modified by polydopamine and sulfonated reduced graphene oxide. Highlights • AEMs are modified by polydopamine and sulfonated reduced graphene oxide. • The modified AEMs is stable and antifouling due to polydopamine coating. • The modified AEMs have monovalent anion selectivity with S-rGO layer. Abstract Developing a durable and antifouling monovalent selective anion exchange membrane is critical in practical electrodialysis (ED) process. Herein, a commercial anion exchange membrane was modified by sulfonated reduced graphene oxide (S-rGO) and polydopamine (PDA). Inspired by biological adhesion from mussels, the PDA coating on the surface of S-rGO-PDA membrane enhanced the stability of S-rGO nanosheets due to strong adhesion. The monovalent anion selectivity was evaluated by means of the Cl - / SO 4 2 - permeselectivity, and stability property was measured by the ion concentration changes of Cl - and SO 4 2 - for a long time application of ED. Moreover, antifouling property was measured by recording the time course of the potential difference in the presence of sodium dodecyl benzene sulfonate (SDBS). The results show that permselectivity of S-rGO-PDA membrane is 2.50, which is higher than pristine membrane (1.08). In addition, S-rGO-PDA membrane is stable, the permselectivity did not change significantly during 70 h ED process. Besides antifouling property of S-rGO-PDA membranes is improved compared with S-rGO membranes. [ABSTRACT FROM AUTHOR]

Modified three-compartment electrodialysis (MTED), a novel process containing intermediate compartment with fluorinated ion exchange membrane, has been applied to the recovery of petroleum sulfonate from petrochemical dispersion. The fluorinated ion exchange membrane has higher degree of crosslinking than heterogeneous ion exchange membrane. The petroleum sulfonate is separated from the petrochemical dispersion during anion migration by the different steric effect of ion exchange membranes. In order to reduce the membrane fouling and increase the current efficiency, the 50 nm ceramic membrane was utilized as the pretreatment of MTED. The result indicated that in total of 99.4 wt% of petroleum sulfonate in the petrochemical dispersion could be recovered at the applied voltage 25 V, flux rate 30 L/h, temperature 40 °C and initial concentration 7.5 wt% (NH 4 ) 2 SO 4 . Simultaneously, the (NH 4 ) 2 SO 4 solution without petroleum sulfonate was received in concentrate compartment of MTED. The results verified the feasibility of MTED on separating the petroleum sulfonate and inorganic salt in petrochemical dispersion, and provided important technical basis for a large-scale procedure of MTED in petrochemical dispersion treatment. [ABSTRACT FROM AUTHOR]

A novel amidoxime (AO) functionalized SBA-15 (AO@SBA-15) with platelet shape and short channels, was prepared by the amidoximation reaction of hydroxylamine with cyanoethyl (CN) functionalized SBA-15 (CN@SBA-15) under N 2 atmosphere. The precursor CN@SBA-15 was initially synthesized by co-condensation of tetraethoxysilane with 2-cyanoethyltriethoxysilane (CTES) using a triblock copolymer (P123) as a structural directing agent in acid medium or via the post-grafting of CTES onto SBA-15 with short channels. The AO@SBA-15 with platelet shape and short channels was employed as an adsorbent to remove U(VI) from an aqueous solution. The g-AO@SBA-15 (precursor prepared by post-grafting method) has higher adsorption capacity (625 mg g −1 ) than that of c-AO@SBA-15 (precursor prepared by co-condensation method) (516 mg g −1 ) at an optimum pH of 6, but with one more preparation step. Results indicated that both the adsorbents showed fast adsorption rate, high selectivity to Na + , K + , Mg 2+ , and Ca 2+ , and reusability for uranium extraction. Therefore, AO-functionalized SBA-15 with short channels is a promising adsorbent to remove uranium ion from an aqueous solution. [ABSTRACT FROM AUTHOR]

High energy consumption and membrane fouling are the two major obstacles that limit the extensive application of nanofiltration technology in treatment of textile and dyeing wastewaters. In this work, traditional polyamide (PA) thin-film composite (TFC) nanofiltration membrane was modified with diethanolamine (DEA) for improved water permeability and antifouling property in the removal of dyes from aqueous solution. The DEA-modified PA-TFC membrane was fabricated by a facile approach of pouring the DEA-aqueous solution on the surface of the nascent polyamide membrane prepared via interfacial polymerization between trimesoyl chloride and piperazine. The covalent attachment of DEA molecules was found to make membrane surface more hydrophilic and less negatively charged while having no influence on the morphological structure and compactness of the active layer. Compared with the traditional PA-TFC membrane, the steady-state water fluxes of the DEA-modified PA-TFC membrane to dye aqueous solutions of Congo red, methyl blue, sunset yellow and neutral red were higher by more than 37.0%, the flux decline ratios due to membrane fouling were lower by at least 35.0%, while the dye removal remained constant, and furthermore, the dye molecules adsorbed and deposited on membrane surface could be more readily washed off by simple hydraulic washing. [ABSTRACT FROM AUTHOR]

[Display omitted] • SBA-15 is granulated by covering hydrophobic nanoparticles through liquid marble. • The resultant granule (SSG) (∼2 mm size) was used as micro-adsorber for U(VI). • SBA-15 in SSG kept 96.2% of adsorption capacity while kept 54.1% in PVC granule. • SSG packed in column experiment proved stability during dynamic adsorption process. • The column device enriched uranium resource and diluted original U(VI) solution. The improvement of the molding process of adsorbent powders is significant for practical application on uranium adsorption in aqueous solution. In this work, the phenomenon of liquid marble was harnessed to prepare silica nanoparticles & SBA-15 granule (SSG). The obtained SSGs were millimeter-sized spherical particles, which overcame the difficulty in application of powders. The maximum adsorption capacity of SSG was 123.2 mg/g under pH of 6 and 25 °C. The SBA-15 existed inside SSG and the active adsorption sites on SBA-15 were not embedded, making them play the role of adsorption as far as possible. Moreover, the porous shell of SSG offered possibility for the delivery of the adsorbate. The transmission of uranyl ions and adsorption process both happened within the millimeter-sized hollow spheres, which proved the role of micro-adsorbers. The adsorption behaviors of SSG were more consistent with the pseudo-second-order model and Langmuir model. The SSGs were packing in column to prove their great stability during dynamic adsorption process. In addition, the dynamic adsorption device achieved the dilution of adsorption solution and enrichment of uranium resources. The SSGs demonstrated their ability in uranium extraction. Moreover, the granulation process also offered a new approach for practical application of powders. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wetting-induced reversible superlyophobic membranes were fabricated. • A novel method of direct surface decoration during phase inversion was proposed. • The membrane could efficiently separate W/O and O/W emulsions in alternation. • The membrane exhibited excellent durability and recyclability. Super-wettable membranes have been extensively investigated due to their prospective applications in oily wastewater remediation. However, it is still a big challenge to develop super-wettable membranes via a facile and rationally designed method. In this work, we proposed a novel strategy to develop wetting-induced superlyophobic polyacrylonitrile (PAN) membranes with reversible wettability via in situ cross-linking polymerization and surface immobilization of nanoparticles during phase inversion process. The resulting membranes exhibited super-amphilic property in air, and were capable of converting their wetting behavior from underwater superoleophobicity to underoil superhydrophobicity with excellent dynamic stability. The membranes also displayed outstanding separation capability toward various surfactant-stabilized emulsions with separation efficiencies exceeding 99.2% under gravity. Moreover, the membranes could be regenerated with high performance preserved using a facile rinsing-and-drying method, and could be repeatedly applied to separate surfactant-stabilized emulsions. This work has made progress in the fabrication of super-amphiphilic membranes with superior separating performance through a facile method, providing great potential in practical application for oily wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monovalent cation permselective membranes were prepared by the combination of surface-crosslink and inorganic nanomaterial doping. • Two-dimensional MOFs were introduced into the monovalent cation permselective membranes for the first time. • 2D MOF, Zn-TCPP, effectively enhanced the ion transport. • Tremendous permselectivity and permeability were obtained simultaneously. Monovalent cation permselective membranes (MCPMs) manifest remarkable effectiveness and potential in lithium extraction whereas facing the challenge to achieve high permselectivity and high Li+ permeability simultaneously. In this work, Zn-TCPP, a kind of two-dimensional nanosheet with abundant negative charges, was successfully synthesized via surfactant-assisted method and introduced into surface cross-linked SPES membrane to fabricate MCPMs. The physicochemical properties, electrochemical properties and Li+/Mg2+ separation performance of resulted MCPMs were systematically estimated. As ions passing through the membrane, dense PVA/GA crosslinked layer separated Li+ and Mg2+ by pore-size sieving effect. Afterwards, uniformly distributed Zn-TCPP nanosheets with rich negative charges and physically adsorbed water molecules elevated the charge density and water content in the membrane and thus expedited Li+ transporting. Therefore, high Li+/Mg2+ permselectivity (P Mg 2 + Li + = 8.99) and Li+ permeation flux (J Li + = 9.12 × 10−9 mol cm−2∙s−1) were obtained. Furthermore, membrane surface resistance was reduced from 108.99 Ω cm2 to 24.12 Ω∙cm2. This study points out the feasibility of the new method for accelerating monovalent ion transport and alleviating the restriction between ion permeation and permselectivity in selective ion exchange membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • TFC polyamide-polyarylate OSN membrane prepared via IP reaction with non-planar rigid twisted structure monomer. • Non-planar rigid twisted monomer effectively manipulates the interfacial polymerization process. • The separation performance of the prepared OSN membrane with PIM structure is remarkably enhanced. • High permeability of ethyl acetate, DMF and methanol and greater than 99% RDB rejection was achieved. • Superior solvent resistance was maintained after immersion in DMF at 80 °C for 63 d. Organic solvent nanofiltration (OSN) has become an emerging green and efficient technique for the separation and purification of organic solvents. The key of the industrial application of this technique is OSN membrane. Till now, current OSN membranes still have relatively low solvent permeance due to the high hydraulic resistance of the dense structure of the OSN barrier layer. Herein, a thin-film composite (TFC) polyamide-polyarylate OSN membrane containing polymers of intrinsic microporosity (PIMs) structure was successfully prepared via interfacial polymerization (IP) using a kind of hydrophilic monomer with rigid twisted structure as aqueous co-monomer together with m -phenylenediamine (MPD). The added co-monomer remarkably enhanced the perm-selectivity of the prepared OSN membrane, with an increase of more than 1.5 times for ethanol permeance, while maintaining the rejection of rhodamine B (RDB, 479 Da) above 99% under the optimal conditions. Moreover, the prepared OSN membrane has a much high permeance to polar solvents, e.g., 110.5, 112.6 and 95.8 L m−2h−1 MPa−1, for ethyl acetate, methanol and DMF, respectively. The most exciting aspect of the prepared OSN membrane is its superior solvent resistance in strong polar organic solvent. It maintained an essentially unchanged solute rejection during 63 d immersion in DMF at 80 °C, and during 120 h continuous cross-flow filtration of the RB-DMF solution at room temperature, which is superior over most of the state-of-the-art literature works, indicating its broad application prospects for separation and purification of polar organic solvent systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PAN-H 1.6 Mn 1.6 O 4 composite nanofiber membranes were prepared by electrospinning. • Nanofiber membrane has higher Li+ adsorption capacity than that of dense membrane. • Nanofiber membrane shows high selectivity and Q e for Li+ in salt-lake brine. • Li+ can be enriched by dynamic adsorption via the column packed with membrane. In this paper, polyacrylonitrile (PAN) as the binder and Li 1.6 Mn 1.6 O 4 as the powder were used to prepare the composite nanofiber flat-sheet membrane-type adsorbent (ESNM-H) via the electrospinning method. The influence factor on membrane adsorption capacity for Li+ were investigated, such as the concentration of PAN, precursor content, and membrane thickness. When the content of PAN and Li 1.6 Mn 1.6 O 4 were 10 wt% and 18 wt%, respectively, the equilibrium adsorption capacity for Li+ on ESNM-H with the thickness of 164 ± 4 μm was 1328 mg/m2, and the actual adsorption capacity of powder H 1.6 Mn 1.6 O 4 incorporated in the nanofiber membrane remained 92% of the unsupported powder. In the artificial salt-lake brine, the adsorption selectivity of ESNM-H for Li+ was higher to other interfering ions (Na+, Ca2+, K+ and Mg2+). After eight cycles, the adsorption capacity of ESNM-H decreased by 8%. The ESNM-H exhibited the better long-term stability. The ESNM-H packed column was enriched with Li+ from 100 mg/L to 726 mg/L after ten consecutive dynamic adsorption–desorption cycles. The overall results show that the composite nanofiber flat-sheet membrane-type adsorbent fabricated via the electrospinning method has potential applications and recyclability in adsorbing Li+ from salt-lake brine. [ABSTRACT FROM AUTHOR]

Highlights: [•] The voltage drop follows the orders: U BP-A-C-BP > U BP-A-BP > U BP-C-BP. [•] Concentration follows the orders: C BP-C-BP > C BP-A-C-BP > C BP-A-BP. [•] Current efficiency follows the orders: ŋ BP-A-C-BP > ŋ BP-C-BP > ŋ BP-A-BP. [•] Energy consumption follows the orders: E BP-A-BP > E BP-A-C-BP > E BP-C-BP. [•] It is wise to choose BP-A-C-BP configuration for preparation the succinic acid. [Copyright &y& Elsevier]

Highlights: [•] Regenerating spent acid produced by HZSM-5 zeolite preparation is proved feasible by BMED. [•] The pure sodium hydroxide in the base chamber can be recycled. [•] The recycled acid solution can replace the pure acid solution completely. [Copyright &y& Elsevier]

Highlights: [•] Natural hydrophilic polymer sericin was coated on the surface of TFC RO membrane. [•] Membrane surface hydrophilicity was improved and negative charge was enhanced. [•] Membrane surface morphology was smoothed. [•] Membrane pure water permeability and salt permeability coefficient were decreased. [•] Modified membrane showed improved fouling resistance to BSA. [Copyright &y& Elsevier]

[Display omitted] • Oxygen-containing azido functionalized GO were synthesized via facile EMR-FD method. • Novel MMMs were synthesized by incorporating azido functionalized GO nanosheets. • Oxygen-containing AGO enhanced interaction with polymer to achieve high compatibility. • AGO/PSF membranes displayed high permeability and good antibacterial performance. Bio-fouling of membranes caused by microorganisms seriously limited the development of membrane technology in practical applications. Design and synthesis of antifouling and antibacterial membranes with high quality are of paramount importance. In this study, we report a facile and safe method of extended Mitsunobu reaction (EMR)-freeze drying (FD) method to achieve oxygen-containing azido functionalized GO (AGO) nanosheets and synthesize novel azido-group functionalized graphene/polysulfone mixed matrix ultrafiltration membranes with enhanced permselective, antifouling and antibacterial property. Unlike reported thermochemical or chemical reactions to modify GO nanosheets, GO nanosheets were functionalized at low temperature which effectively prevented the decomposition of structural frame of pristine GO materials and the self-stacking phenomenon. Because of strong interactions between oxygen-containing AGO nanosheets and polymer matrices, high dispersity and interfacial compatibility were obtained in polysulfone membranes, resulting in sharp decrease of interfacial defects. Different kinds of techniques include SEM, ATR-FTIR, XPS, XRD, TEM and EDX were used to investigate the structure and morphology of AGO nanosheets and blended membranes, and cross-flow filtration experiments, anti-fouling and antibacterial test were applied to predict the behavior of hybrid membranes. High performance AGO/PSF mixed matrix membranes with excellent anti-fouling ability were successfully synthesized, which exhibited pure water flux as large as 245.1 L m−2h−1 with satisfactory rejection of 95.8% for BSA. Moreover, the prepared membranes displayed good antibacterial activity against E. coli and S. aureus in long-term duration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Separation efficiency of PA NF membrane was improved by modification with APTES. • Modification was fulfilled via surface cross-linking and in-situ condensation. • Homogenized pore size and reduced mean pore diameter were achieved by modification. • Removal efficiency to both cationic and anionic dye aqueous solutions was improved. • Anti-fouling resistances to model foulants CTAB, HA and BSA were enhanced. Surface modification has been adopted to tune surface property of nanofiltration membrane for improved separation performance. However, it has rarely been explored to modulate membrane pore size distribution. Here, we reported a novel modification strategy combined with surface cross-linking and in-situ condensation for fabricating composite nanofiltration membrane with reduced and homogenized pore size. The strategy was fulfilled by soaking the surface of nascent polyamide-based membrane with an aqueous solution of 3-aminopropyltriethoxysilane (APTES). Membrane physico-chemical property analyses demonstrated that the hydrolyzed APTES molecules bonded onto membrane surface through amidation and esterification reactions with the residual acyl chloride groups, and chemically combined with each other through condensation reaction. Modification was found to hydrophilize membrane surface, homogenize pore size and reduce mean pore diameter. The modification under desired conditions led to an improvement in pure water permeance from 12.2 to 14.0 l/m2 h bar, a decrease in geometric mean pore diameter from 0.71 nm to 0.63 nm, and a decline in geometric standard deviation from 1.32 to 1.23. Permeation test results showed that the APTES-modified membrane also exhibited improved removal performance to methylene blue and cresol red removal and enhanced antifouling resistances to model foulants cetyltrimethylammonium bromide, humic acid and bovine serum albumin. [ABSTRACT FROM AUTHOR]

Abstract: Submerged nanofiltration of anionic dye aqueous solution by laboratory-fabricated sodium carboxymethyl cellulose (CMCNa)/polypropylene (PP) thin-film composite hollow fiber membrane was investigated in this paper. The CMCNa/PP thin-film composite membranes were prepared through dip-coating CMCNa skin layer on the outer surface of polypropylene microporous hollow fibers followed by cross-linking with FeCl3. The molecular weight cut-off (MWCO) and surface zeta potential of the tailor fabricated membrane were estimated through permeation tests using different PEG solutions and measurements of surface steaming potential, respectively. Submerged nanofiltration tests were then performed with anionic dye solutions under different conditions. It was found that, at neutral pH, the negatively charged CMCNa/PP composite hollow fiber membrane with a MWCO of about 700Da could effectively remove anionic dyes (Congo red and Methyl blue) from aqueous solution with good long-term performance stability and anti-fouling property through submerged nanofiltration. The dye retention and water permeability was affected by the trans-membrane pressure, the dye concentration as well as the presence of salt in the solution. The dye retention, water permeability and salt rejection rate to aqueous solution containing 2000mg/l Congo red and 10,000mg/l NaCl were 99.8%, 7.0l/m2 hbar, and lower than 2.0%, respectively. [Copyright &y& Elsevier]

Abstract: Interfacially synthesized thin-film composite (TFC) aromatic polyamide reverse osmosis membranes were modified by depositing a thermo-responsive polymer poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-co-Am)) with low critical solution temperature (LCST) on membrane surface, and the modified membranes showed significantly improved antifouling properties and cleaning efficiency. In the experiments, membrane modifications were conducted in situ with dilute P(NIPAM-co-Am) solutions under different modifying conditions (e.g., P(NIPAM-co-Am) concentration and deposition time), after which fouling properties of the virgin and modified membranes were studied through cross-flow fouling experiments using bovine serum albumin (BSA) aqueous solution under different feed concentrations and pHs, and membrane cleaning tests were also carried out with the fouled membranes using de-ionized water under different feed temperatures. The membrane properties were also characterized by ATR-FT-IR, contact angle and streaming potential measurements as well as permeation tests. It was found that membrane modification improved the water permeability and fouling resistance to BSA due to the increased membrane surface hydrophilicity, and that the phase transition of the thermo-responsive polymer surface coating layer above LCST facilitated the removal of foulant located on membrane surface. Furthermore, the in situ membrane surface modification approach would be of particular interest for treating existing commercial membranes in their original module assembly. [ABSTRACT FROM AUTHOR]

[Display omitted] • –COOH and Ag-functionalized carbon nanospheres are successfully synthesized. • TFN membranes containing functionalized CNs are prepared for RO application. • Carboxyl groups in nanofillers significantly influence the membrane structure. • TFN-Cs-COOH membrane shows high water flux of 63 LMH and NaCl rejection over 96.8%. • The TFN–Cs–COOH/Ag membrane possesses remarkable anti-bacterial property. In this study, carboxyl group-functionalized carbon nanospheres (CNs–COOH) and silver-coated products (CNs–COOH/Ag) were successfully realized and used as nanofillers to fabricate thin-film nanocomposite (TFN) membranes via the interfacial polymerization of m -phenylenediamine (MPD) and trimesoyl chloride (TMC) solutions. The structure of the functionalized CNs modified TFN membranes (TFN–Cs–COOH, TFN–Cs–COOH/Ag) was significantly different from that of the CNs modified TFN (TFN–Cs) and TFC membranes, as the carboxyl groups in the nanofillers strongly influence the process of interfacial polymerization. The permeability and anti-fouling performances of the TFN membranes were significantly enhanced owing to the changes in the membrane structure. The water fluxes of the TFN–Cs–COOH and TFN–Cs–COOH/Ag membranes were respectively 91.9% and 73.2% higher than that of the TFC membrane, with the NaCl rejection exceeding 96%. The nanofillers of CNs–COOH/Ag with monodispersed silver nanoparticles (NPs) resulted in outstanding anti-bacterial performance in the TFN–Cs–COOH/Ag membrane. Overall, this work demonstrates that, when functionalized carbon NPs are used as nanofillers, the practical performance of TFN membranes can be improved for reverse osmosis. [ABSTRACT FROM AUTHOR]

Abstract: 2-Hydroxypropyltrimethyl ammonium chloride chitosan/polyacrylonitrile (HACC/PAN) positively charged composite nanofiltration (NF) membrane was prepared using HACC as active layer, PAN ultrafiltration (UF) membrane as support layer, and toluene diisocyanate (TDI) as cross-linking reagent. FTIR-ATR spectrum was employed to characterize the cross-linking on the resultant membrane surface. Besides, some characteristics such as the permeability of pure water and the rejection performance to different salt solutions were evaluated. At 20°C and 30Lh−1 of cycling flow, the permeability of pure water through this membrane was 8.96kgm−2 h−1 MPa−1. The rejection to different salt solutions increased in the order of Na2SO4, MgSO4, NaCl and MgCl2. [Copyright &y& Elsevier]

Abstract: A novel composite nanofiltration (NF) membranes were prepared using quaterinized chitosan as a selective layer, poly(acrylonitrile) UF membrane as a support layer and anhydride mixture as cross-linking reagent. The images of these membranes were characterized by scanning electron microscope, and the other characterizations such as pure water permeability, molecular weight cut-off, rejection and swelling were investigated. Molecular weight cut-offs tested were in the range of 550–580Da (in NF range). Both pure water permeability and swelling in water decreased, whereas rejection increased with an increase in anhydride mixture concentration, indicating pore contraction and the increase in both hydrophobicity and pore tortuosity due to cross-linking. Besides, the rejection declined with the increasing feed concentration, whereas it was not affected by feed cross-flow rate. The order of rejection to different salts followed the decreasing of CaCl2, MgCl2, NaCl, KCl, MgSO4, Na2SO4 and K2SO4, suggesting the positively charged characteristic of the NF membranes. And the rejections to MgCl2, CaCl2 solutions reached up to 0.95, so the membranes developed can be used for the hardness removal in water treatment process. [Copyright &y& Elsevier]

Abstract: A water-soluble copolymeric membrane material containing tertiary amine and carboxyl groups for CO2 facilitated transport have been synthesized by radical polymerization of DMAEMA (2-N,N-dimethyl aminoethyl methacrylate)–AA (acrylic acid). The composite membranes were prepared with copolymer of DMAEMA–AA as separation layer and polysulfone (PS) ultra-filtration membrane as support. The permeation rates of the membranes for pure CO2 and CH4 were investigated. The results show that the copolymeric membrane possesses a higher permeance of CO2. The membrane displays a CO2 permeance of 6.12×10−7 cm3 (STP)/cm2 sPa, and a CH4 permeance of 2.4×10−9 cm3 (STP)/cm2 sPa at 299K, 1.140kPa of gas pressure. The results with the mixed gas are not as good as those obtained with pure gas because of the coupling effects between CO2 and CH4. [Copyright &y& Elsevier]

Abstract: Elevated CO2 levels in a closed space or room are of big concerns in many situations. Controlling the CO2 level within a certain range is one of the most important tasks in a life support system. In this paper, a 10l photobioreactor integrated with a hollow fiber membrane module was constructed to remove CO2 from air by using the photosynthetic microalga, Chlorella vulgaris. The effects of the inlet CO2 concentration and the introduction of the membrane module on microalgal CO2 fixation were investigated. The results showed that the proper inlet CO2 concentration was determined to be 1.0%, based on the description of the growth characteristics of the microalga, and the gas exchange efficiency was improved greatly when the membrane module was adopted. Compared with an ordinary photobioreactor, not only the retention time of the smaller and more uniform gas bubbles in the new membrane-photobioreactor increased from 2s to more than 20s, but also the dissolved oxygen (DO) dropped by a factor of 30, resulting in the enhancement of the CO2 fixation rate from 80 to 260mgl−1 h−1. When the operating conditions were controlled at cell density of 2.0×107 cellsml−1, inlet gas flow rate of 3lmin−1, and light intensity of 157.6 μEm−2 s−1 at 25–30°C, the 1.0% (v/v) CO2 in the input aeration gas could be reduced to 0.3% in the discharged gas. Using normal room air (0.04% CO2) as feed, the CO2 concentration in the discharged gas could be decreased to the boundary value of 0.015%, indicating that the novel membrane-photobioreactor by intensifying the process of CO2 conversion and fixation during the microalgal photosynthesis may be a promising solution to CO2 removal in a closed space or room. [Copyright &y& Elsevier]

• F-TiO 2 @PP membrane with coral synapses is formed by in-situ cross-linking polymerization. • F-TiO 2 @PP membrane shows outstanding oil-collecting capacity with ultra-high oil fluxes. • Water rejection efficiency of 99.7% is reached by gravity-driven filtration. • F-TiO 2 @PP membrane also has high separation performance for seawater and oil. Super-hydrophobic F-TiO 2 @PP membranes were developed from polypropylene (PP) non-woven fabric by in situ cross-linking polymerization of trifluorofluorooctyl methacrylate (FOMA) and sol–gel-derived titanium dioxide with vinyltriethoxysilane (VTES). Due to the formation of super-hydrophobic "coral"-like synapses on the filamentous surfaces of PP non-woven fabric, F-TiO 2 @PP membranes showed extremely high water contact angles up to 157° and capability of rapidly absorbing oil drops. The F-TiO 2 @PP membranes were also able to expel water from water-in-oil emulsions with robustly high oil permeate fluxes (up to 11,000 L m−2h−1 under gravity), water removing efficiency (up to 99.7%), re-usability and long-term stability even at the presence of surfactant and salts. Such superior performance could lead to potential applications in rapid collection and efficient purification of recovered oily organic components from waste liquids or accidental oil discharges in marine or continental situations. [ABSTRACT FROM AUTHOR]

• The NaCl solution improved the permeation flux. • The NaCl solution expanded the membrane pore. • The flux respond to the NaCl concentration. • The membrane remained the selectivity in the NaCl solution. The preparation methods of nanofiltration (NF) membranes are various. Designing composite layer structures can obtain NF membranes with special properties. In our work, the polyethyleneimine/trimesic acid NF membrane exhibited high permeability. Based on this, the NaCl solution caused the permeate flux improving (ion-promoting-penetration phenomenon), and the flux was responsive to the solution concentration within a certain range. The detailed analysis of cross-linked structure, membrane pores, and solutions were made. The ion-promoting-penetration effect level, the highest growth rate Rg, could achieve about 70% (from 40 to 68 L m−2 h−1). This feature was still significant in mixed salt solutions, which had the potential to be applied to deep water treatment. After long-term treatment with the NaCl solution, the PEI/TMA membrane still maintain the excellent desalination performance (rejection of MgCl 2 , >90%). The discussion of these contents was beneficial to deepen the understanding of the NF process. [ABSTRACT FROM AUTHOR]

• A new type of monovalent anion-selective amphoteric membrane was fabricated. • The blend AIEMs show the good miscibility between the two polymer components. • The swelling ratio of the optimized blending AIEM is as low as 10.9% at 25 °C. • The Cl–/SO 4 2– selectivity of the most optimized AIEM in ED is 21.8 at 2.5 mA cm−2. It is of significant importance to develop highly monovalent anion-selective membranes (MASM) having stable structure for a wide range of applications. To realize the efficient monovalent/bivalent anion separation, in this work, three amphoteric ion-exchange membranes (AIEMs) through blending were fabricated for use in electrodialysis (ED). The three membranes were prepared by blending amino-containing poly(arylene ether sulfone) (PAES-NH 2) with 10, 15, and 20 wt% of sulfonated polysulfone (SPSf), respectively, followed by grafting imidazolium salt-terminated side alkyl chains on PAES backbone. Our investigations demonstrate that each transparent AIEM shows good miscibility between the two components, which has been verified by a homogeneous structure via SEM observation and by an even distribution of N element via EDX mapping. In the ED process at a current density of 2.5 mA cm−2, AIEM with 15 wt% of SPSf shows the superior perm-selectivity (Cl–/SO 4 2–) of 21.8, relative to many reported MASMs having modified surfaces (<6.0), which is synergistically contributed by (i) electrostatic repulsion difference from the negatively-charged sulfonate groups against monovalent Cl– ions and bivalent SO 4 2– ions and (ii) hydrated energy difference of hydrated Cl–/SO 4 2– ions. This work thus presents a strategy to guide the architectural design of advanced MASMs. [ABSTRACT FROM AUTHOR]

• TFN RO membranes were prepared by incorporating p -aminophenol modified GO into polyamide skin layer. • The incorporation of mGO reduced the hydrophilicities and the thickness of functional layers. • The optimized RO membrane shows the superior water flux of 23.6 L·m−2·h−1 and NaCl rejection rate of 99.7%. • RO membrane with mGO exhibits bacterial killing ratios of 96.78% and 95.26% against E. coli and S. aureus. Innovative approaches to restraint bacterial adhesion and growth on membranes are significantly needed to avoid membrane performance decaying for biofouling. In this work, a series of thin film nanocomposite (TFN) reverse osmosis (RO) membranes has been prepared by incorporating nano-fillers of p -aminophenol-modified graphene oxide (mGO) into the polyamide skin layer via interfacial polymerization. Our investigations demonstrate that the introduction of mGO nano-fillers into the functional skin layers reduces the hydrophilicities with the water contact angles drop from 69.6° to 48.2° and meanwhile decreases the thickness of functional skin layers from 240 nm to 50 nm, relative to pristine polyamide RO membrane without nano-fillers. As a result, the as-prepared TFN RO membrane at optimized conditions shows a water flux of 23.6 L·m−2·h−1 and a NaCl rejection rate of 99.7%, reflecting a remarkable promotion in water flux (by 24.5%) compared with the pristine RO membrane. In addition, the data statistics of the live/dead fluorescent imaging assay demonstrate that TFN RO membrane with mGO exhibits bacterial killing ratios of 96.78% and 95.26% against E. coli and S. aureus at the additive loading of 0.005 wt%, which are much higher than RO membrane with GO (90.64%; 90.43%) and pristine RO membrane (4.95%; 2.48%). This work demonstrates a facile way to TFN RO membranes with good separation performance and desirable antibacterial capacities. [ABSTRACT FROM AUTHOR]

• Three composite AEMs from QPSU and PVA blends have been fabricated for ED. • The swelling ratio of optimized M 2 -0.05 AEM was significantly reduced to 4.7% at 20 °C. • The chloride ion conductivity of M 2 -0.05 reaches 23.5 mS cm−1 at 20 °C. • M 2 -0.05 has the superior NaCl removal ratio of 74.6% within 120 min (vs. 61.06% of AEM-Type II). It is significant to develop anion exchange membranes (AEMs) with efficient ionic transport and desirable stabilities (mechanical and dimensional) for various applications, including electrodialysis (ED). In this paper, three types of composite AEMs based on quaternized polysulfone (QPSU) and polyvinyl alcohol (PVA) blends: QPSU/PVA composite AEM (M 0), potassium thioacetate (PT) modified QPSU blending with PVA (M 1) and QPSU blending with 4-formylbenzoic acid (FBA) modified PVA (M 2 -X, X = mass ratio of the FBA with the values of 0.05 and 0.20), have been investigated. Our investigation demonstrates that the swelling ratios of M 1 and M 2 -0.05 were significantly reduced to 10.9% and 4.7% at 20 °C, much lower than M 0 (16.9%). This can be due to the formed hydrogen-bonding network via OH from PVA and >C O from PT structure on PSU within M 1 or the ionic crosslinking interactions between COO– from FBA and >N+– on QPSU within M 2. Though the free volume inside AEM matrix is reduced, the chloride ion conductivities of M 1 and M 2 -0.05 reach 20.5 mS cm−1 and 23.5 mS cm−1 at 20 °C. In ED application, the optimized M 2 -0.05 has the highest NaCl removal ratio of 74.6% within 120 min (vs. 61.06% of the commercial AEM-Type II), and exhibits better desalination performance with high current efficiency (98.0% vs.92.8%) and lower energy consumption (2.2 kWh kg−1 NaCl vs. 2.4 kWh kg−1). The simple preparation process and good ED performance of M 2 -0.05 are indicative of its potential ED application. [ABSTRACT FROM AUTHOR]