Support Layer Research Articles

Facile morphological tuning of thin film composite membranes for enhanced desalination performance

Polyamide (PA) membranes with a thin selective layer have been widely investigated for desalination and water treatment. Several modifications have been proposed over the years to tailor the morphology of such thin film composite (TFC) membranes by altering the support and/or selective layers to achieve superior performance. In this study, a facile approach towards fabricating a highly wrinkled selective layer has been demonstrated through bio-inspired modification of the support layer with Y-type zeolites. Results showed that incorporating zeolites in a smaller dimension (200 nm) produced by a unique ball milling technique is favorable for a defect-free selective layer in comparison to larger commercial zeolites. PA membranes formed by the interfacial polymerization (IP) of Piperazine (PIP) and 1,3,5-Benzenetricarbonyl trichloride (TMC) revealed highly wrinkled morphology due to the presence of zeolites in the TFC interlayer. At optimum fabrication conditions, the membrane exhibited a fast transport of 22.5 ± 2.2 Lm-2h-1bar-1 with a salt rejection of 48.6, 91.3, 99.1, and 99.5% for NaCl, MgCl2, MgSO4, and Na2SO4, respectively. Besides the unique preparation of zeolites in smaller dimensions, the novelty of this study lies in the facile membrane pretreatment before IP to achieve wrinkled PA membranes for enhanced nanofiltration performance.

Mechanical Properties of Polyamide Fiber-Reinforced Lime–Cement Concrete

Lime–cement concrete (LCC) is a type of lime-based concrete in which lime and cement are utilized as the main binding agents. This type of concrete has been extensively used to construct support layers for shallow footings and road backfills in some warm regions. So far, there has been no systematic research conducted to investigate the mechanical characteristics of polyamide fiber-reinforced LCC. To address this gap, LCC specimens were prepared with 0%, 0.5%, 1%, and 2% of polyamide fibers (a synthetic textile made of petroleum-based plastic polymers). Specimens were then cured for 3, 7, and 28 days at room and oven temperatures. Then, the effects of the fibers’ contents, curing conditions, and curing periods on the mechanical characteristics of LCC, such as secant modulus, deformability index, bulk modulus, shear modulus, stiffness ratio, strain energy, failure strain, strength ratio, and failure patterns, was investigated. The results of the unconfined compressive strength (UCS) tests showed that specimens with 1% fiber had the highest UCS values. The curing condition and curing period had significant effects on the strength of the LCC specimens, and oven-cured specimens developed higher UCS values. The aforementioned mechanical properties of the LCC specimens and the ability of the material to absorb energy significantly improved when the curing period under the oven-curing condition was increased, as well as through the application of fibers in the mix design. Based on the test results, a simple mathematical model was also established to forecast the mechanical properties of fiber-reinforced LCC. It is concluded that the use of polyamide fibers in the mix design of LCC can both improve mechanical properties and perhaps address the environmental issues associated with waste polyamide fibers.

Ultrasound-Driven Defect Engineering in TiO2-x Nanotubes─Toward Highly Efficient Platinum Single Atom-Enhanced Photocatalytic Water Splitting.

Single-atom catalysts (SACs) have demonstrated superior catalytic activity and selectivity compared to nanoparticle catalysts due to their high reactivity and atom efficiency. However, stabilizing SACs within hosting substrates and their controllable loading preventing single atom clustering remain the key challenges in this field. Moreover, the direct comparison of (co-) catalytic effect of single atoms vs nanoparticles is still highly challenging. Here, we present a novel ultrasound-driven strategy for stabilizing Pt single-atomic sites over highly ordered TiO2 nanotubes. This controllable low-temperature defect engineering enables entrapment of platinum single atoms and controlling their content through the reaction time of consequent chemical impregnation. The novel methodology enables achieving nearly 50 times higher normalized hydrogen evolution compared to pristine titania nanotubes. Moreover, the developed procedure allows the decoration of titania also with ultrasmall nanoparticles through a longer impregnation time of the substrate in a very dilute hexachloroplatinic acid solution. The comparison shows a 10 times higher normalized hydrogen production of platinum single atoms compared to nanoparticles. The mechanistic study shows that the novel approach creates homogeneously distributed defects, such as oxygen vacancies and Ti3+ species, which effectively trap and stabilize Pt2+ and Pt4+ single atoms. The optimized platinum single-atom photocatalyst shows excellent performance of photocatalytic water splitting and hydrogen evolution under one sun solar-simulated light, with TOF values being one order of magnitude higher compared to those of traditional thermal reduction-based methods. The single-atom engineering based on the creation of ultrasound-triggered chemical traps provides a pathway for controllable assembling stable and highly active single-atomic site catalysts on metal oxide support layers.

Thermally oxidized PAN as photocatalyst support layer for VOCs removal

Photocatalytic filter plays a key role in VOCs removal and ensuring the long-term durability of photocatalytic filter is essential for increasing their lifespan in real-world industrial application. However, how to unlock the stability of organic supporting materials as photocatalytic filter has not been taken into account. In this work, photocatalyst TiO2 nanoparticles were successfully immobilized on a polyacrylonitrile (PAN) nonwoven using a solvent swelling method, followed by a thermal oxidation treatment. The photocatalytic efficiency of prepared PAN nonwovens in VOCs removal was investigated and the effect of surface treatments and thermal oxidation process on fibers photostability and thermal characteristics were explored. The obtained thermal-oxidized TiO2@PAN nonwoven showed photocatalytic efficiencies of 75% and 92% for the degradation of toluene and formaldehyde gases, respectively, under simulated sunlight. Compared with the TiO2@PAN nonwoven, the photo-induced degradation rate of oxidized-TiO2@PAN nonwoven decreased by 43%, and TGA-DTG results demonstrated a superior thermal stability of the oxidized PAN sample. The findings of this research can facilitate the application of novel PAN-based nonwoven filters in photocatalytic removal of VOCs by providing higher efficiency, improved thermal stability and photostability.

Tailoring the CO2 permeation of Pebax1657/polyether imide thin film composite membrane via embedding Ag-based metal-organic framework

Thin-film composite/nanocomposite (TFC/TFN) membranes count as the latest version of carbon capture membranes characterized by their excellent gas permeance, great selectivity, cost-effectiveness, and the ability to separately manage and tune the constituents of the individual layer. In this regard, Pebax®1657 embedded with synthesized Ag-BTC metal-organic frameworks (MOFs) was coated on the polyether imide (PEI) support layer to produce TFNs. To assess the impacts of Ag-BTC particles (carboxyl-rich surface particles) on the features of the constructed TFC/TFN membranes and their gas permeation qualities, several CO2/N2 and CO2/CH4 separation experiments (mixed and pure gas testing) were carried out. Ag-BTC particles were distributed appropriately within the Pebax1657 matrix, improving the gas permeability (particularly for CO2) and enhancing CO2/N2 and CO2/CH4 separation factors. A simultaneous increase in CO2 permeability and gas pair selectivities was observed with rising feed pressure. A 394.97 Barrer CO2 permeability and 38.20 CO2/N2 and 21.25 CO2/CH4 selectivities were obtained for the TFN filled with 3 wt% Ag-BTC at 10 bar and 30 °C. A mixed gas test also showed a similar trend but lower values than a pure one. The results for the humidified conditions exhibited higher CO2 permselectivities in comparison with the dry gas given the water molecules facilitate the CO2 transportation through the Pebax®1657 matrix. Finally, enhancing Ag-BTC filler content and increasing the input pressure provided excellent conditions for approaching Robeson’s limit.

High performance forward osmosis membrane with ultrathin hydrophobic nanofibrous interlayer

The novel thin film composite (TFC) forward osmosis (FO) membrane with electrospinning nanofibers as support layer can alleviate internal concentration polarization (ICP). While the macropores of the nanofiber support layer cause defects in the polyamide (PA) layer. Therefore, hydrophobic polyvinylidene fluoride (PVDF) fine nanofibers were used as an interlayer to modulate the process of interfacial polymerization (IP) in this study. The results showed that the introduction of the interlayer improved the hydrophobicity of the support layer for achieving uniform, thin and defect-free selective polyamide (PA) layer. The water flux of TFC-PVDF was 58.26 LMH in the FO mode of 2 M NaCl, which was two times higher than that of the unmodified FO membrane. Lower reverse salt flux (4.91 gMH) and structural parameter (179.43 μm) alleviated the ICP. In addition, TFC-PVDF membrane showed good anti-fouling performance for SA (flux recovery ratio of 93.97%) due to high hydrophilicity, low zeta potential and low roughness. This study provides an easy and promising method to prepare defect-free PA selective layer on the macropores nanofiber support layer. The novel FO membrane shows high desalination performance and anti-fouling properties.

A novel porous asymmetric cation exchange membrane with thin selective layer for efficient electrodialysis desalination

Ion exchange membranes (IEMs) are widely used in various electrochemical fields. Generally, identifying a solution for the trade-off between ion conductivity and dimensional stability is crucial for the further development of IEMs in the electrodialysis (ED) process. This study aimed to prepare a novel type of cation exchange membrane for electrodialysis desalination. Different from the previous cation exchange membranes with the thick and dense cross-section structure, the as-prepared asymmetric composite membranes in the present work composed of a thin and dense skin layer and a porous support layer via the pore-filling process of the skin layer of the porous poly (ether sulfone) (PES) membrane. Benefiting from such structural features, effective ion transport and dimensional stability were simultaneously achieved in the case of low ion exchange capacity. Ultimately, the optimal sulfonated poly (ether sulfone)-poly (ether sulfone) (SPES-PES) composite membrane simultaneously achieved ion transport enhancement, low swelling rate at 80 °C, and better mechanical stability compared to pure sulfonated poly (ether sulfone) (SPES) membranes. When applied to ED, the prepared 40 %SPES-PES membrane exhibited more excellent desalination performance (91.9%), higher current efficiency (127.5%), and lower energy loss (5.55 Kw·h·kg−1) compared to commercial membrane.

Modification of TFC membrane using green materials for nitrophenol removal from aqueous media

This study focused on preparing high-performance PVDF-supported TFC membrane for application in 2,4-dinitrophenol removal from aqueous media. Two modification methods were applied to enhance the permeability of water and rejection of 2,4-dinitrophenol: 1) improve the surface properties of the support layer using green interlayer (tannic acid and polydopamine), and, 2) using different amounts of tannic acid as an additive of amine solution to control structure of selective polyamide layer. The surface properties and morphology of fabricated membranes were characterized by attenuated total reflection – Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle test. The performance of the as-prepared membranes was evaluated by 2,4-dinitrophenol removal from an aqueous solution. Among the modified-PVDF supported membranes, the one modified with a blend of tannic acid and polydopamine as an interlayer showed the best performance (water permeability of 1.9 LMH/bar and rejection of 98%). For PVDF-supported TFC membrane, by incorporating TA (0.025 to 0.2%) as an additive of the amine solution, the pure water permeability and solute rejection were increased from 0.81 LMH/bar and 92% to 2.6 LMH/bar and 96%, respectively (at TA amount of 0.1%).

Metaverse-oriented visual art quality enhancement strategies: a field architecture design and fuzzy assessment theory perspective

Visual art was originally measured by viewing and appreciating graphic works, and there was no previous research into ways to improve the quality of visual art. With the rapid development of visual arts and technology, the question of how to improve quality has become an urgent one. As the most cutting-edge and hottest concept in the international arena today, the development and application of metaverse technology has widely drawn the close attention of various industries, including management, economy, education, and art. However, there is no in-depth and clear research on the concept of metaverse in the field of art, especially in the field of visual art. We believe that the creation of visual art in the context of metaverse will be an important direction for art development in the future, and can also greatly contribute to the improvement of the quality of metaverse visual art presentation. Therefore, we focus on the issue of visual art quality assessment in our research, and propose a theory and method of metaverse-oriented future visual art quality assessment. The method focuses on the G1-entropy value method to calculate the weights in visual arts, combines qualitative research with quantitative research, and proposes the improvement path and countermeasures for visual arts. In summary, our research aims to address the theoretical approaches to the design of the metaverse field architecture and the assessment of art quality for the future introduction of the metaverse. The main contributions of our research are focused on the following three aspects: 1. The construction of the visual art field architecture draws on the functional requirements analysis method of system science simulation, considering that the entire visual art metaverse field architecture is constructed at three levels: the bottom data support layer, the middle technical support layer and the upper technical application layer. 2. The G1-entropy combination weighting method is used to derive the importance ranking of visual art quality indicators and identify key factors, and to derive suggestions for quality improvement based on the key indicator factors. More importantly, we also build a field architecture for future-oriented visual arts in this study, which bridges the gap in the structural design of visual arts after the introduction of the future concept. Our present study makes a great contribution to the application of visual art quality enhancement, focusing on the analysis of new concepts and the improvement of old methods, building a new scene of organic combination of new technologies and traditional visual art, with practical research theoretical support for the promotion and progress of the disciplinary field.

Carbon Capture Membranes Based on Amorphous Polyether Nanofilms Enabled by Thickness Confinement and Interfacial Engineering.

Thin-film composite membranes are a leading technology for post-combustion carbon capture, and the key challenge is to fabricate defect-free selective nanofilms as thin as possible (100 nm or below) with superior CO2/N2 separation performance. Herein, we developed high-performance membranes based on an unusual choice of semi-crystalline blends of amorphous poly(ethylene oxide) (aPEO) and 18-crown-6 (C6) using two nanoengineering strategies. First, the crystallinity of the nanofilms decreases with decreasing thickness and completely disappears at 500 nm or below because of the thickness confinement. Second, polydimethylsiloxane is chosen as the gutter layer between the porous support and selective layer, and its surface is modified with bio-adhesive polydopamine (<10 nm) with an affinity toward aPEO, enabling the formation of the thin, defect-free, amorphous aPEO/C6 layer. For example, a 110 nm film containing 40 mass % C6 in aPEO exhibits CO2 permeability of 900 Barrer (much higher than a thick film with 420 Barrer), rendering a membrane with a CO2 permeance of 2200 GPU and CO2/N2 selectivity of 27 at 35 °C, surpassing Robeson's upper bound. This work shows that engineering at the nanoscale plays an important role in designing high-performance membranes for practical separations.

Constructed "sandwich" structure to obtain recyclability and high rejection rate high-flux CA@HMSN@h-BN/PDA membrane for efficient treatment of dye wastewater

It is necessary to develop a nanofiltration membrane that can remove dye molecules efficiently and is not easily polluted for the treatment of textile industry wastewater. A novel high-flux CA@HMSN@h-BN/PDA membrane with a "sandwich" structure was obtained by assembling the support layer of the Hollow mesoporous silica nanoparticles (HMSN), and the isolation layer of the h-BN/PDA on the Cellulose acetate (CA) membrane. HMSN was synthesized using ZIF-8 as a self-sacrificial template to provide improved permeability. h-BN/PDA obtained by modifying hexagonal boron nitride (h-BN) with polydopamine (PDA) brought higher hydrophilicity, rejection rate, and stability to the membrane. The study solved the problem that the membrane separation process requires sacrificing flux and recyclability for high rejection rates. CA@HMSN@h-BN/PDA membrane has a super-hydrophilic property (water contact angle of 22.5°) and high pure water flux (4419.4 L·m−2·h−1·bar−1). Meanwhile, the CA@HMSN@h-BN/PDA membrane achieves a high rejection rate (over 99.5%) due to the special "sandwich" structure. Through cycling experiments, CA@HMSN@h-BN/PDA membranes exhibit recyclability. More importantly, CA@HMSN@h-BN/PDA membranes maintain stable performance in complex environments, such as extremely acidic/alkaline or inorganic salt interference environments. Thus the CA@HMSN@h-BN/PDA membrane has the potential for future wastewater treatment.

Novel interface enhancement strategy enables SiC fiber membrane for high-temperature gas/solid filtration

The high gas permeance of ceramic membranes is the most important indicator of hot-gas filtration. Ceramic membranes made of fibers show significant potential for filtering dust-laden gases owing to their high porosity and high gas permeance. A novel method is proposed for preparing a SiC fiber separation layer on a rigid ceramic support that endows the membrane with a high porosity. However, the interfacial adhesion between the support and separation layers was low as there were insufficient connection points. Therefore, a solvothermal method was proposed for the in-situ vertical growth of TiO2 nanocords on the surface of a SiC support (SiC–TiO2). Next, a SiC fiber separation layer was deposited on the SiC–TiO2 support to improve the interfacial adherence. The fabrication parameters of the SiC fiber layer, such as the solid content of the coating slurry and sintering procedure of the separating layer, were investigated in detail. At a SiC fiber content of 6 wt%, spray-coating times of 2, and sintering temperature of 1150 °C, a complete fiber layer was successfully deposited on the rigid ceramic support. The resulting membrane had a thickness of 100 μm, porosity of 91%, average pore diameter of 6.8 μm, and gas permeance of 440 m3·m−2·h−1·kPa−1. In the filtration of dust-laden gas containing SiO2 as simulated dust (average particle size, 0.3 μm), the rejection rate was >99.9%; further, after four cycles of filtration–backwashing, the pressure drop was <0.82 kPa. The outlet dust content was less than 0.1 mg m−3. Moreover, this membrane exhibited superior filtration ability at 500 °C. The findings of this study can aid the fabrication of ceramic fiber membranes with a high gas permeance and high interfacial adherence for industrial applications.

Facile spray-printing of hydrophobic and porous gas diffusion electrodes enabling prolonged electrochemical CO2 reduction to ethylene

The twelve-electron carbon dioxide reduction reaction (12e– CO2RR) constitutes a sustainable alternative to steam cracking for the production of ethylene (C2H4), the world's most coveted organic compound. State-of-the-art gas diffusion electrodes (GDEs), while exhibiting promising faradaic efficiencies for C2H4 electrosynthesis, suffer from poor long-term stability, particularly at elevated applied currents, due to catalyst delamination and flooding of the diffusion layer. Herein, through the development and optimisation of a novel, facile and flexible spray-printing method, hydrophobic porous carbon and copper electrodes with different architectures are obtained readily by using suspensions consisting of two fugitive solvents, which provide larger surface areas for the three-phase boundary and improve the hydrophobicity/flooding tolerance of the electrodes, due to their increased surface roughness and binder (PVDF) content. These structures, with pore sizes as low as 60 μm, transform the surfaces from incomplete wetting to highly hydrophobic, and can be employed as gas-diffusion, microporous or supportive layers, in addition to acting as a supporting substrate for the copper-based catalyst. These layers are spray-printed in a stacked assembly upon polymer film and carbon paper substrates, and ultimately result in an extended duration of enhanced C2H4 production at applied currents of up to 200 mA cm−2 via multiple configurations. Through layer-by-layer spray-printing with a hydrophobic microporous layer and porous catalyst support, this inventive approach can efficiently control the hydrophobicity of the GDE, and extends the cathode operation time by a factor of 6, with a maximum faradaic efficiency of 52% attained, and an average of >30% maintained over 12 h of continuous electrolysis, demonstrating the versatility of this technique for engineering highly durable GDEs for selective CO2 reduction toward multi-carbon (C2+) commodities, energy storage devices and other electrochemical applications.

Numerical analysis of the relation between the porosity of the fuel electrode support and functional layer, and performance of solid oxide fuel cells using computational fluid dynamics

The development of the hydrogen industry brings new technological challenges. Solid oxide fuel cells (SOFCs) seem to be one of the leading devices for hydrogen conversion and its production while operating in its reverse mode (as an electrolyser). Fine-tuning of SOFC microstructure might extend cells life and boost their performance. The article presents original numerical studies of the performance of solid oxide fuel cells, based on the OpenFuelCell model, extended by fuel and oxidant concentration loss equations. Transport phenomena in the porous structure of the anode functional layer (AFL) and the anode support layer (ASL) were simulated using the modified Fick's law (MFL) and the Knudsen diffusion coefficient. The presented research focuses on the influence of fuel distribution in fuel electrode of SOFC together with reacting zones and on the influence of AFL and ASL microstructure characteristics on cell performance. The studies included porosity in the range of 30%–60% for both types of anode layers. The obtained results showed a significant impact of the porosity characteristics on the SOFC performance and indicated the possible direction for further improvement. Numerical studies have shown that an increase in anode layers porosity of 30% allows for an increase in cell efficiency of even 15%. Experimental, as well as numerical results, showed that above a porosity of 49%, further increasing the porosity has no strong effect on the results. Also, a novelty in the work and an important part of it is the comparison of the impact of microstructure manipulation of the two anodic layers. Improvement of ASL microstructure allows to better, more homogeneous, fuel distribution inside the anode. Additionally, it increases the concentration of the fuel in the functional layer by up to 8%, which leads to increase in SOFC performance.

Fabrication of Textured Ni-Coated Carbon Tubes for a Flexible Strain Sensor: Effect of the Device Elastic Modulus on Sensor Performance.

The exploration of flexible resistive sensors with excellent performance remains a challenge. In this paper, a nickel-coated carbon tube with a textured structure was prepared as a conductive sensitive material and inserted into the poly(dimethylsiloxane) (PDMS) polymer; interestingly, the sensor performance was controlled by the elastic modulus of the matrix resin. The results show that Pd2+ may be adsorbed by the active groups on the surface of a plant fiber as a catalytic center for the reduction of Ni2+. After 300 °C annealing, the inner plant fiber would be carbonized and attached to the outside of the nickel tube; to be precise, the textured Ni-encapsulated C tube was fabricated successfully. It is worth noting that the C tube serves as a layer of support for the external Ni coating, providing sufficient mechanical strength. In addition, resistance sensors with different properties were prepared by controlling the elasticity modulus of the PDMS polymer by introducing different contents of curing agents. The limit uniaxial tensile strain was enhanced from 42 to 49% and sensitivity reduced from 0.2 to 2.0% with the elasticity modulus of the matrix resin increasing from 0.32 to 2.2 MPa. As expected, the sensor is obviously appropriate for the detection of elbow joints, human speaking, and human joints with the reduction of the elasticity modulus of the matrix resin. To be precise, the optimal elastic modulus of the sensor matrix resin would facilitate the improvement of its sensitivity to monitor different human behaviors.

A self-supported agZIF-UC-4 glass membrane for gas separation

Metal-organic framework (MOF) membranes have become promising candidates for gas separation due to their adjustable structure, high separation performance, and environmental friendliness. However, the emergence of grain boundary defects, and interface defects between the support layer and separation layer significantly decrease the gas separation performance of MOF membranes. Herein, a self-supported ZIF (zeolitic imidazolate framework) glass membrane is fabricated, eliminating grain boundary defects and cracks through the molten-liquid phase. The fluorine-based linkers with high electronegativity and polarizability are introduced to enhance agZIF-62(a and g denote amorphous and glass, respectively) interaction of CO2 and CH4. The CO2/N2 and CH4/N2 ideal selectivity of agZIF-UC-4 membrane (fluorine-based, UC-4 named by Cambridge University) reach 36 and 6.2, respectively. In addition, the CO2 and CH4 permeance of the agZIF-UC-4 membrane with an independent separation layer and the non-grain boundary has improved to 4752 and 818 GPU, respectively. Under the mixed gas condition, agZIF-UC-4 membrane exhibits good separation performance, exceeding the 2019 Mckeown upper bond of CO2/N2. Moreover, agZIF-UC-4 membrane has good stability for CO2/N2 and CH4/N2 under continuous operation and variable pressure testing. Hence, the self-supported agZIF-UC-4 membrane is a potential candidate for preparing MOF glass membranes with good gas separation performance.

Forward-Reverse Osmosis Processes for Oily Wastewater Treatment

In this study, the feasibility of Forward–Reverse osmosis processes was investigated for treating the oily wastewater. The first stage was applied forward osmosis process to recover pure water from oily wastewater. Sodium chloride (NaCl) and magnesium chloride (MgCl2) salts were used as draw solutions and the membrane that was used in forward osmosis (FO) process was cellulose triacetate (CTA) membrane. The operating parameters studied were: draw solution concentrations (0.25 – 0.75 M), oil concentration in feed solution (FS) (100-1000 ppm), the temperature of FS and draw solution (DS) (30 - 45 °C), pH of FS (4-10) and the flow rate of both DS and FS (20 - 60 l/h). It was found that the water flux and oil concentration in FS increase by increasing the concentration of draw solutions, the flow rate of FS and the temperature for a limit (40oC), then, the water flux and oil concentration decrease with increasing the temperature because of happening the internal concentration polarization phenomenon. By increasing the oil concentration in FS and the flow rate of the DS, the water flux and oil concentration in FS decreased, while it had a fluctuated behavior with increasing pHof oily wastewater. It was found also that MgCl2 gives water flux higher than NaCl. So the values of resistance to solute diffusion within the membrane porous support layer were 55.93 h/m and 26.21 h/m for NaCl and MgCl2 respectively. The second stage was applied reverse osmosis process using polyamide (thin film composite (TFC)) membrane for separating the fresh water from a diluted (NaCl) solution using different parameters such as draw solution concentration (0.08–0.16 M), feed flow rate (20–40 l/h).

Low-cost ceramic membranes manufacture using INKJET technology for active layer deposition and validation on membrane bioreactors

The fabrication of eco-friendly ceramic membranes based on low-cost raw materials, using digital INKJET printing techniques for active layer deposition and its validation in a membrane bioreactor (MBR) has been studied. The raw materials used in the manufacture of the support layer were UA50/2 clay, chamotte, calcium carbonate and potato starch. A MBR laboratory plant was operated to treat municipal wastewater with three ceramic membranes with different grammages in the selective layer deposition. The membrane performance at laboratory scale was evaluated in terms of transmembrane pressure (TMP) evolution for a constant permeate flux, permeate quality and mixed liquor characteristics. From these experiments, it was selected the membrane which obtained the lowest TMP profile maintaining appropriate water quality parameters (chemical oxygen demand (COD) removal percentage around 90% and turbidity around 0.06 NTU). This membrane was also operated at pilot plant scale in order to validate it at higher scale. Results indicated that TMP values were in the range of 0.06 and 0.1 bar, COD removal percentage was around 98% and microbiology analysis demonstrated that the quality of the effluent, according to European regulation 2020/741, can be classified as Class A and it can be reused for non-potable purposes.

Regulation of dopamine forward osmosis membrane via inorganic salt and macro-porous substrates for pharmaceutical concentration

Dopamine (DA) with good designability could self-polymerize into polydopamine (PDA) with various polymerization states in alkaline solution. However, the poor structural controllability of PDA leads to serious PDA hyper-polymers, making DA difficulty to be used as sole aqueous phase monomer during conventional interfacial polymerization (IP) for membrane preparation. In this work, the organic solvent forward osmosis (OSFO) membranes were fabricated via substrate-floating interfacial polymerization (SFIP) method with DA as sole aqueous phase monomer and macro-porous polyether sulfone (PES) membrane with pore size of 0.1–0.22 μm as substrates. Inorganic salt such as NaCl was employed as aqueous phase additive, which not only effectively regulated the oligomeric polymerization state of PDA but also promoted DA diffusion. The macro-porous substrate could enlarge the reaction contact area and relieve the internal concentration polarization in support layer. The resulting OSFO membranes exhibited an excellent ethanol flux of ∼10.70 L m−2 h−1 and lower reverse LiCl flux of ∼0.53 g m−2 h−1, as well as a high tetracycline concentration efficiency of >15 % for 1 h run whatever the tetracycline concentration in the feed (500–2000 mg/L). This work provides new insights into the fabrication of high-performance OSFO membrane for solvent recovery and pharmaceutical concentration.

Ultrathin breathable and stretchable electronics based on patterned nanofiber composite network

Wearable comfort and performance modulation of stretchable electronics are the focus of next-generation electronic skin. Herein, we developed ultrathin breathable and stretchable electronics by introducing elaborate patterned electrospinning technology. The principle of patterned electrospinning technology is studied, and this technology is proved to be universal for variety of polymers experimentally. The effect of electrospinning time and patterned pore size on the performance of patterned electrospun film is studied. Using an ultrathin patterned stretchable thermoplastic polyurethane electrospun film (10 μm) as a supportive layer, a patterned nanofiber composite network is constructed, combined with Ag nanowires and thermoplastic polyurethane/Ag nanofibers. The patterned nanofiber composite network is achieved with outstanding stretchability and conductivity, while the mean sheet resistance is as low as 1.59 Ω/sq and can be stretched to 110% strain. The electromechanical performance of nanofiber composite network is controlled by the pore size of patterned electrospun film, which can be applied for stable, breathable, and stretchable electrode and strain sensor. Hence, the elaborate patterned electrospinning technology and the fabrication and modulation of patterned nanofiber composite network offer a method for stretchable electronics.