NaCl Rejection Research Articles

UiO-66-NH2 MOF/organosilica mixed-matrix membrane for water desalination

A new amine-functionalized UiO-66/organosilica mixed-matrix membrane was fabricated and explored for pervaporation (PV) water desalination. The incorporation of amine-functionalized UiO-66 (UiO-66-NH2) into the BTESE-derived organosilica networks endowed the membrane with enhanced hydrophilicity and dense network structure, leading to an improvement in water flux and NaCl rejection. The UiO-66-NH2/BTESE mixed-matrix membrane was proved to be highly effective for desalination of saline water in concentrations from 1 to 13 wt% of dissolved NaCl. Moreover, the membrane exhibited superior structural stability under a continuous PV desalination operation up to 100 h, delivering water permeance of >3.1 × 10−6 mol m−2 s−1 Pa−1 combined with NaCl rejection of >99.9%. The high water permeance was mainly ascribed to the specific pore structure and the preferential interactions between pore channels and water molecules, and the excellent salt rejection was primarily based on the sieving effect. The proposed UiO-66-NH2/BTESE mixed-matrix membranes show great prospects as an alternative for concentrated brine desalination.

Epoxide-based TFC membranes with tunable performance in the tight nanofiltration range

Membrane technology offers promise as a breakthrough separation technology in many applications, but is frequently limited by the chemical stability of currently available membrane materials. Recently developed membranes utilizing epoxide-based chemistry have shown great potential as intrinsically stable thin-film composite membranes in water-based applications. However, as these membranes are in their infancy, many synthesis parameters are still to be explored. In this study, the versatility of epoxide chemistry is exploited to demonstrate its potential to serve as a new platform for membrane synthesis, even beyond the field of aqueous applications. It is proven here how the membrane performance can be tailored in a controllable way between 20 – 85% NaCl rejection with a water permeance between 0.5 – 3 L m−2 h−1 bar−1 by simply selecting epoxide monomers and initiators of different size and functionality. A systematic increase in water permeance and salt passage was observed for epoxide monomers that exhibit a lower functionality and a lower number of aromatic groups, while a threshold nucleophilicity and aliphatic chain length of the initiator are required to obtain a salt-selective layer. This work demonstrates the possibility to easily and predictably tune membrane performance in the tight nanofiltration range, while simultaneously achieving a better understanding of the synthesis-structure-performance relationship of this new class of promising membranes.

Revealing the selective separation of organics from salty solution in novel aqueous-aqueous membrane extraction co-driven by concentration and pressure difference

Aqueous-aqueous membrane extraction (AAME) has great potential to revolutionize industrial wastewater treatment, achieving the value-added organic product recovery with low operation cost. Here, we first reported the feasibility, performance and mechanism of selective separation of three typical organics (phenol, ethanol and sodium dodecyl sulfate (SDS)) from salty solution not only in common concentration-difference driven but also in novel concentration-pressure-difference co-driven AAME using porous polyvinylidene fluoride (PVDF), non-porous polydimethylsiloxane (PDMS) and composite PVDF/PDMS membranes. In concentration-difference driven AAME, phenol and ethanol were separated from NaCl solution through three membranes, while SDS permeation only occurred on wetted porous PVDF membrane. Note that, volatile phenol and ethanol transported across the porous PVDF and composite PVDF/PDMS via volatilization-diffusion and solution-diffusion. In concentration-pressure-difference co-driven AAME, highest phenol (10.7) and ethanol fluxes (34.7 g m2 h−1) were obtained through composite PVDF/PDMS membrane (ΔP = 3 kPa) and PVDF membrane (ΔP = 9 kPa), respectively, with complete NaCl rejection. These data showed suitable membrane and high ΔP were beneficial to promote organics transmembrane transport. However, overload ΔP increased the membrane wetting risk on porous membranes. Once membrane was wetted, organics transmembrane mass transfer was simplified to direct pore-flow filtration. These findings provide a crucial step toward understanding the potential of AAME in resource recovery from industrial wastewater.

Development of a Lycopodium powder-based superhydrophobic nanofiber membrane suitable for desalination

A biobased, green, inexpensive additive, Lycopodium particles, which are spores of the “Lycopodium clavatum” plant, were incorporated in the poly(vinylidene fluoride) PVDF electrospun nanofiber membranes (ENMs) for desalination by direct contact membrane distillation (DCMD). Superhydrophobic ENMs were prepared using this additive (PVDF-ENMs-Lyc). Thanks to their morphological structure and their prominent surface superhydrophobicity (anti-wetting) character, the resulting PVDF-ENMs-Lyc exhibited an improved liquid entry pressure (LEP), a high void volume fraction (greater than 87.2%), a good salt rejection factor (greater than 99.93%) and a reasonably high permeate flux (greater than 51.76 kg·m−2·h−1) at 80 °C, which are of great practical importance for water desalination by DCMD. The optimum membrane prepared with 3 wt% Lycopodium in the dope solution demonstrated a stable permeate flux of 52.4 ± 0.6 kg·m−2·h−1 with an electrical conductivity around 4.76 ± 0.46 μS/cm (NaCl rejection factor of 99.998 ± 0.036%) during 25 h DCMD desalination experiment using 35 g/L NaCl aqueous solution (similar to seawater concentration). The presented results pave the way for superhydrophobic nanofibrous membrane engineering suitable for membrane contactors by electrospinning in a single step without surfactants, organic additives, or chemical post-treatments, just by the incorporation of a green additive like Lycopodium powder.

In-Situ Modification of Nanofiltration Membranes Using Carbon Nanotubes for Water Treatment.

Modification of thin-film composite (TFC) nanofiltration (NF) membranes to increase permeability and improve separation performance remains a significant challenge for water scarcity. This study aimed to enhance the permeability and selectivity of two commercial polyamide (PA) NF membranes, NF90 and NF270, by modifying them with carbon nanotubes (CNTs) using microwave (MW)-assisted in-situ growth. The conducting polymer, polypyrrole (Ppy), and a ferrocene catalyst were used to facilitate the growth process. Chemical and morphological analyses confirmed that the surface of both membranes was modified. The NF270-Ppy-CNT membrane was selected for ion rejection testing due to its superior permeability compared to the NF90-Ppy-CNT. The modified NF270 membrane showed a 14% increase in ion rejection while maintaining constant water permeability. The results demonstrated that it is feasible to attach CNTs to a polymeric surface without compromising its functional properties. The Spliegler-Kedem model was employed to model the rejection and permeate flux of NF270-Ppy-CNT and NF270 membranes, which indicated that diffusive transport contributes to the modification to increase NaCl rejection. The present study provides a promising approach for modifying membranes by in-situ CNT growth to improve their performance in water treatment applications, such as desalination.

Constructing carboxylated MXene interlayer in polyamide nanofiltration membrane for enhancing perm-selectivity and antifouling performance

Constructing nanomaterials interlayer for high-performance polyamide membranes is a popular technique in brackish water desalination, while selecting a suitable nanomaterial and convenient method for constructing interlayer remains a challenge. Herein, easily-modified MXene nanosheets were carboxylated to obtain excellent hydrophilicity, negative charge, and good compatibility with polymer, which were applied to construct carboxylated MXene (COOH-MXene) interlayered polyamide membranes by facile brushing process. COOH-MXene nanosheets have good compatibility with polyamide and supporting membranes, and make the membrane surface wrinkled, hydrophilic and negatively charged. The optimized membrane achieves a water flux of 12.9 Lm−2h−1bar−1, 2.9 times of the blank membrane. The MgSO4 rejection is improved to 99.1%, and the NaCl rejection is only 11.4%, displaying excellent selectivity for monovalent and divalent ions. Moreover, the prepared membranes have good antifouling properties and long-lasting desalination performance. This study presents a new approach to brackish water desalination by constructing COOH-MXene interlayered membranes.

Antifouling polymeric nanocomposite membrane based on interfacial polymerization of polyamide enhanced with green TiO2nanoparticles for water desalination

In the present investigation, the preparation and characterization of polyamide/TiO2as thin film nanocomposites (TFN) for brackish water desalination was investigated. TiO2nanoparticles (NPs) were synthesized by a green method using thyme plant extract as a reducing and capping agent. The TiO2NPs was successfully prepared in pure crystalline anatase phase with 15 nm size, and −33.1 mV zeta potential. The antimicrobial tests confirmed the antimicrobial activity of TiO2against gram-positive and gram-negative bacteria. In addition, TiO2NPs showed a good photocatalytic activity in degradation of methylene blue dye. TFN based on interfacial polymerization was enhanced by embedding 5% of the greenly synthesized TiO2NPs within the polyamide thin film active layer. The incorporation of TiO2NPs was confirmed by SEM, atomic force microscope (AFM), surface wettability, and FTIR. Membranes performance was investigated based on flux, salt rejection and fouling resistance. The antifouling was examined using bovine serum albumin (BSA) as protein fouling by dead-end cell filtration system at 2 bar. The results showed the TFN increased in water flux by 40.9% and a slight decrease in NaCl rejection (6.3%) was observed, with enhancement in antifouling properties. The flux recovery rate of the modified TFN membranes after fouling with BSA solution was enhanced by 21.5% (from 61.7% for TFC to 83.2% for TFN). Also, they demonstrated remarkable anti-biofouling behavior against both bacterial strains.

Engineering Ultra-Permeable and Antifouling Water Channel-based Biomimetic Membranes toward Sustainable Water Purification

Water channel-based biomimetic membranes (WBMs) are gaining increasing attention due to the effectiveness of water channels in enhancing water permeability and breaking the permselectivity trade-off. However, the ultra-permeable WBMs may suffer from severe membrane fouling issue because a high-water flux tends to result in an accelerated fouling and thus compromises the benefits gained from the usage of water channels. Herein, a novel in-situ modification protocol was proposed to enhance the antifouling performance of ultra-permeable WBMs. The nanovesicles incorporated with aquaporin (AQP) water channels were functionalized with polyethylene glycol brushes (i.e., PEGylation) via a facile self-assembly approach and subsequently encapsulated in the selective layer of thin-film composite membranes through interfacial polymerization. The modification had minimal impact on the function of AQPs, resulting in WBMs with a high water permeance (∼8.2 LMH/bar) and good NaCl rejection (96.4%) comparable to the unmodified WBMs. Moreover, the in-situ modification drastically enhanced the surface hydrophilicity, which endowed the membrane with a superior fouling resistance to organic foulants. The improved fouling resistance ensured a more sustainable operation of ultra-permeable WBMs, particularly in scenarios that favor high water fluxes. This facile modification strategy provides an efficient way to fabricate ultra-permeable and antifouling WBMs for sustainable water purification.

Polymer Inclusion membranes with long term-stability in desalination via membrane distillation

This work explored the feasibility of implement of polymer inclusion membranes (PIMs) in the desalination industry. The methyltrioctylammonium oleate (MTOAO) was imbedded in a blend of polyvinylidene fluoride (PVDF) and polysulfone (PSU) prepared via Non-Solvent Induced Phase Separation (NIPS). The investigation encompassed the analysis of the chemical compositions and morphologies of the novel PIMs, with the objective of identifying the optimal MTOAO concentration within the PVDF/PSU matrix. The membrane characterizations revealed that addition of 33% of MTOAO in PVDF/PSU significantly increased the porosity (from 73.4% to 89.8%) and conferred a highly-hydrophobic character (WCA=123°). In direct contact membrane distillation experiments, PVDF/PSU doped with 33% of MTOAO resulted in a flux of 21.9 kg·m−2·h−1 and a 99.98% NaCl rejection where the salinity and temperature were 30 g/L and 70 °C, respectively. Remarkably, the inclusion of the MTOAO led 625% in transmembrane flux of. Moreover, PVDF/PSU load with 33% of MTOAO demonstrated a long-term stable performance over 10 weeks, whereas the PVDF/PSU membrane exhibited a poor stability in terms of salt rejection because of pore wetting caused by the poor hydrophobic character. Lastly, the performance of the process was positively assessed by desalting seawater from Atlantic Ocean.

Solvent-activated thin-film nanocomposite membranes molecularly tuned with macrocyclic cavities for efficient water desalination and boron removal

Tuning the permeation properties of thin-film nanocomposite (TFN) membranes through the molecular redesign of their underlying nanoarchitecture is a challenging but important task for realizing reverse osmosis (RO) desalination performance above the trade-off limit. Activation by organic solvents, as one of the most facile methods to rearrange the microstructure of RO membranes, can effectively boost the water permeability but is constrained by the significant rejection loss. Here, we innovated an integrative approach whereby soluble organic macrocyclic cavitands (OMCs) with molecular-sieving open cavities were simultaneously dissolved in the activating solvent during membrane post-treatment such that their infiltration into the interfacially polymerized (IP) polyamide (PA) layer enabled the formation of a nanocomposite structure with recovered or even enhanced salt rejections. In this work, prefabricated polysulfone-supported pristine PA membranes were transformed into cavity-bearing nanocomposites after being treated with methanol solutions containing 4-sulfocalix[4]arene (SCA4), an OMC structure with a strongly size-sieving ∼ 3.0 Å cavity opening. This integrative solvent-cavitand treatment allowed their water permeability to increase by up to 129% from 1.98 to 4.53 Lm−2h−1bar−1 with uncompromised or even enhanced NaCl rejection, leading to overall separation performances that well surpassed the permeability-selectivity trade-off line. Meanwhile, these SCA4-infiltrated TFN membranes also demonstrated promising boron removal efficiency with an increase in both the water permeability and boron rejection from 1.95 to 4.17 Lm−2h−1bar−1 and 96.9% to 97.4% at pH = 10, respectively. With the wide array of solvent and soluble nanoarchitecture options, this study could provide a new and versatile direction in designing high-performance TFN membranes for environmentally important separations.

Facile hydrophilization of polyethylene substrate by in situ polymerization of m-phenylenediamine for preparing high-performance polyamide reverse osmosis membrane

Polyethylene (PE) microporous membrane-supported thin-film composite (TFC) polyamide membranes have received growing attention owing to their low cost, superior separation performance, and excellent chemical robustness. Developing facile and cost-effective methods to hydrophilize PE membranes is essential for the scale-up of PE-supported TFC membranes. Here, a facile approach of in situ polymerization of m-phenylenediamine (MPD) was employed to hydrophilize the PE membranes for the first time. Characterizations showed that both the outer surface and the interior of the PE membrane were homogeneously coated with poly(m-phenylenediamine) (PMPD). The hydrophilicity of the modified PE membrane was dramatically enhanced with the water contact angle decreasing from ∼120° to ∼72° and water flux at 2 bar increasing from 0 to ∼640 L m−2 h−1. The high surface porosity and appropriate surface hydrophilicity of the MPD-modified PE membrane together with the excellent coating uniformity favor the formation of a highly permselective polyamide active layer. The outstanding coating stability was demonstrated through different tests. The cost of the MPD-modified PE membrane is estimated to be less than 1% of that of the conventional substrates. Furthermore, high-performance and low-cost reverse osmosis (RO) membranes were prepared via interfacial polymerization on the MPD-modified PE substrates. The PE-supported RO membrane exhibited an excellent separation performance with NaCl rejection of 99.3%, pure water permeance of 1.3 L m−2 h−1 bar−1, and long-term operating stability. The proposed hydrophilization strategy of PE membrane is facile, low-cost, environmentally friendly, and reliable, and thus has a brilliant prospect for industrialization.

Visible‐light photocatalytic membranes based on heterostructured Fe3O4‐doped g‐C3N4/TiO2 catalysts

AbstractBACKGROUNDDesalination membranes have been widely in demand for separating dyes and salts. However, dyes are easily adsorbed on/in the membranes, deteriorating membrane performance. Coupling photocatalysis and membrane separation might be a promising strategy for efficiently alleviating membrane fouling. Aiming at the defects of single catalyst, this work constructed photocatalytic membranes based on heterostructured Fe3O4‐doped g‐C3N4 (FeCN)/TiO2 catalysts by successively filtrating FeCN aqueous dispersion and titanium butoxide/isopropanol solution on the hydrolyzed polyacrylonitrile substrate.RESULTSThe H‐bonds among TiO2, FeCN and substrate lead to excellent load stability of the photoresponsive layer. Due to the low‐potential conduction band and high conductivity of Fe3O4 and the low‐potential conduction band of TiO2 in FeCN/TiO2, electrons can be more easily transferred to guarantee the high separation efficiency of electrons and holes. Hence the membrane not only exhibited superior permeability (104 L m−2 h−1 bar−1) and dye desalting performance (Coomassie brilliant blue R250 rejection of >98.80% and NaCl rejection of <7.00%), but also displayed highly efficient and stable dye photodegradation.CONCLUSIONThe degradation efficiency surpassed that reported in the literature in comparable circumstances, and the recovery rate of permeability still reached 89.12% after three fouling–photodegradation cycles. This work provides new opportunities for designing high‐efficiency self‐cleaning membranes to solve membrane fouling based on low‐cost materials. © 2023 Society of Chemical Industry (SCI).

Regulation of micro-structure and surface property of SWRO membrane via introducing albumin into polyamide layer for improving permselectivity

The concerned trade-off effect between water permeability and permselectivity hinders further improvement of the performance based on dense polymeric membranes. Here, seawater reverse osmosis (SWRO) membranes with higher water-salt permselectivity and water permeability were prepared by introducing albumin concentrated and crystallized from chicken egg white (EW) into aqueous solution before interfacial polymerization (IP) to regulate the micro-structure and surface property of the aromatic polyamide layers. Due to the hydrophilic nature and its multi-functional groups, EW albumin could disperse homogeneously in aqueous solution during the interfacial polymerization process. The deposited EW albumin on polysulfone (PSf) substrate could also increase the surface charge as well as its hydrophilicity. Due to the higher and more vertical leaf-like structures, together with the rougher surfaces and more hydrophilic surface, the water flux of db-0.1 membrane increased by 21.29 % compared to the original db-0 membrane, which reached 49.66 L·m−2·h−1. Meanwhile, because of the higher cross-linking degree and the more negatively charged property, db-0.1 membrane which exhibited the best water permeability also showed the best NaCl rejection of 99.66 %. It provides new sights on simultaneous regulation of micro-structure and surface property of SWRO membranes for improving water permeability and permselectivity via a facile incorporation procedure.

In situ assembly of graphitic carbon nitride/polypyrrole in a thin-film nanocomposite membrane with highly enhanced permeability and durability

Although thin-film nanocomposite (TFN) membranes have been proposed as a competitive approach for improved reverse osmosis performance within the last decade, their intrinsically poor organic-inorganic interfacial compatibility and low durability still hinder further upscaling. In this study, a new in situ assembly strategy is proposed to solve this dilemma by using polypyrrole (PPy) to build a bridge between polyamide matrix and nanomaterial (graphitic carbon nitride, g-C3N4) and further fabricate g-C3N4/PPy-incorporated TFN membrane. The synthesized g-C3N4/PPy nanocomposites are hybridized into the interfacial polymerization process, which endows the TFN membrane with a smaller “ridge-valley”, higher hydrophilic and thinner polyamide layer. With 0.005 wt% of g-C3N4/PPy, the water permeability of TFN membrane is increased to 377 % (4.0 L·m−2·h−1·bar−1), while keeping a similar NaCl rejection (99.1 %) to pure polyamide membrane. Importantly, the resulting TFN membrane exhibits high chlorine resistance in acidic, neutral and alkaline environments. Moreover, the TFN membrane has superior antifouling performance for organic, inorganic and mixed organic-inorganic foulants, which is of vital importance for the long service life of TFN membranes. This study offers a facile avenue to solve the application needs of advanced TFN membranes for efficient desalination with stable high-quality water.

Constructing high-performance GO membrane with pore-adjustable polymer nanoparticles

Desalination of textile wastewater is an effective measure to reduce environmental pollution and realize resource reuse. Graphene oxide (GO) membrane is regarded as one of the first choices for textile wastewater desalination due to its chemical resistance, strong mechanical properties, and adjustable interlayer channels. Here, we propose a polyaniline (PANI) particle incorporation strategy and use the dedoping effect of polyaniline to provide an additional permeation pathway through one-step alkali treatment to accelerate water molecule transport. Polyaniline (PANI) doped with polystyrene sulfonic acid (PSS) nanoparticles were synthesized and incorporated into GO membranes, followed by crosslinking of glutaraldehyde (GA) for stability and alkali treatment for more porosity generation. The as-prepared BGO/PANI-PSS membrane with 30% PANI-PSS addition displayed a flux of 70.4 LMH/bar, 99.3%, and 4.8% rejection for Congo red and NaCl, respectively, exhibiting 5.9 times higher permeability than that of GO membrane with similar dye rejection. This work provides a facile strategy for designing GO composite membranes for dye/salt separation.

Influence of pH and NaCl on the rejection of glycine and triglycine in binary solutions for desalination with diananofiltration

Nanofiltration can be used as the last step in the purification of the biomolecules that are present in many industrial by-products, such as biological protein hydrolysates. The present study explored the variation in glycine and triglycine rejections in binary solutions with NaCl at different feed pHs with two nanofiltration membranes: MPF-36 and Desal 5DK with molecular weight cut-offs of 1000 and 200 g mol−1, respectively. First, water permeability coefficient showed a n-shaped curve with feed pH, which was more evident for the MPF-36 membrane. Second, membrane performance with single solutions was studied and the experimental data were fitted with the Donnan steric pore model with dielectric exclusion (DSPM-DE) to explain the variations of solute rejection with feed pHs. Glucose rejection was assessed to estimate the membrane pore radius of the MPF-36 membrane, and a pH dependence was observed. For a tight membrane (Desal 5DK), glucose rejection was close to unity and the membrane pore radius was estimated from the glycine rejection in the feed pH range from 3.7 to 8.4. Glycine and triglycine rejections showed a pH-dependence with a u-shaped curve, even for the zwitterion species. In binary solutions, glycine and triglycine rejections decreased with NaCl concentration, especially in the MPF-36 membrane. Triglycine rejection was always higher than NaCl rejection and it was estimated that triglycine can be desalted using a continuous diananofiltration the Desal 5DK membrane.

Cellulose nanocrystals-microfibrils biocomposite with improved membrane performance

This study investigates eco-friendly membrane biocomposites derived from biomass, utilizing cellulose microfibrils (CMF) as the main membrane material. Cellulose nanocrystals (CNC), isolated from rice husk, were added as reinforcing fillers in CMF flat sheet membranes. CNC with concentrations of 0%, 10%, 20%, and 30% were employed. Scanning electron microscopy images revealed that CNC influenced the surface profile and the pore structure of the membranes, reducing the porosity by 23%. The empty areas formed by CMF interaction were effectively filled by CNC. This modified membrane resulted in an increase in NaCl rejection of up to 16%. Dynamic water contact angle demonstrated the role of CNC in enhancing permeability, with a shorter spreading time of 13 min. It was also confirmed by the highest flux of 351 L/m− 2h−1 under pure water flux conditions. Mechanical properties were significantly improved, with a 125% increase in tensile strength and a modulus of 329 MPa. The distribution of CNC within the membranes filled pores and enhanced CMF interaction, facilitated by abundant hydroxyl groups in CNC. Overall, this study highlights the potential of eco-friendly membrane biocomposites derived from biomass, offering valuable insights for the development of sustainable and efficient membrane materials.

Novel TFC membrane with crosslinked PMIA active layer fabricated by the T-FLO technique for dye desalination

Poly (m-phenyleneisophthalamide) (PMIA) is a promising candidate for membrane material resulting from its excellent thermal and chemical stability. Being the linear molecular structure, almost all studies have been carried out on PMIA as a substrate material for thin-film composite (TFC) membranes rather than an active layer. Here, amino-epoxide crosslinkers were introduced into the PMIA dope solution to modify the molecular structure for the first time. Employing the casting coupled solvent evaporation deposited the crosslinked PMIA (CPMIA) thin-film. The effect of crosslinker type and concentration on the morphology and the ion permeance have been investigated systematically. That is, achieving the separate optimization of the active layer. Based on the CPMIA thin-film with the best ion permeation, novel TFC membranes (TFC-CPE) with CPMIA active layer were generated successfully via the thin-film liftoff (T-FLO) technique for the first time. Results demonstrated that TFC-CPE had desirable dye desalination performance. For feeding solution containing 100 ppm CR and 1 g L−1 NaCl, the permeance was 25.17 L m−2 h−1 bar−1. CR rejection was 99.88% and NaCl rejection was 6.30%. The selective coefficient α was up to 793.9. It also demonstrated that the TFC-CPE had excellent thermal resistance, anti-fouling capability and long-term stability. In conclusion, the novel TFC membrane has a promising future for in-situ dye wastewater treatment. This work throws light on the PMIA modification and the preparation of the TFC membrane with a novel active layer.

Transport properties investigations of nanocomposite membranes incorporating titanate nanowires for water desalination

AbstractImprovement of membrane properties is an important issue to enhance the efficiency of water permeation processes. Nanocomposite membranes are gaining prominence in this field due to the particular properties of these materials. In the present study, incorporating titanate nanowires (TNW) into the cellulose acetate (CA) matrix allowed getting a nanocomposite membrane with modified characteristics. Morphologic and physical–chemical properties of the synthesized membranes were characterized by Fourier transform infrared spectrometry and scanning electron microscopy analysis, presenting a dense, uniform membrane formation with a highly dispersed inorganic phase when low amounts of particles were added. The membranes were tested by measuring water flux and salt rejection. The results showed that the incorporation of inorganic nanostructures into polymer membranes affects their transport properties. It was observed an increase of three times in water flux, reaching from 1.33 to 4.0 L/h m2, with NaCl rejection over 65%. Membranes with such characteristics could be specially designed for nanofiltration or forward osmosis processes as a promising application for water desalination or energy generation.

High-Flux lamellar MoSe2 membranes for efficient dye/salt separation

Membrane-based technology is emerging as an efficient technique for wastewater treatment in recent years. Membranes made up of two-dimensional materials provide high selectivity and water flux compared to conventional polymeric membranes. Herein, we report the synthesis and use of MoSe2 membrane for dye and drug separation in wastewater, mainly from textile and pharmaceutical industries. The as-prepared MoSe2 membrane shows ∼ 100% rejection for organic dyes and ciprofloxacin drug with a water flux reaching up to ∼ 900 Lm-2h-1bar-1. Further, the MoSe2 membrane shows lower NaCl rejection of ∼ 1.9% for the dye/salt mixture. The interlayer spacing in the MoSe2 membrane allows the water molecules and ions from the salt to pass through freely but restricts the movement of large contaminants. The membrane is stable against the bovine albumin serum fouling with a flux recovery rate of 96%. It also shows good performance even in harsh environments (pH 3–10). To the best of our knowledge, the MoSe2 membranes were fabricated for the first time for wastewater treatment application. The dye/salt separation performance of the MoSe2 membrane is significantly better than several other membranes. This work highlights the promising potential for using two-dimensional materials for textile and pharmaceutical wastewater treatment.