Inorganic Composite Membranes Research Articles

A facile strategy for the preparation of carbon nanotubes/polybutadiene crosslinked composite membrane and its application in osmotic energy harvesting

The osmotic energy between riverine water and seawater can be converted into electricity by reverse electrodialysis (RED). However, the facile fabrication of advanced RED membranes with high energy conversion efficiencies, large areas, and excellent mechanical properties remains a challenge. Carbon nanotubes (CNTs) exhibit excellent conductivity and provide suitable channels for ion transport but cannot form membranes independently, which limits the related applications in osmotic energy conversion. Herein, a new organic–inorganic composite membrane is prepared by combining hydroxyl-terminated polybutadiene as a matrix and carbon nanotubes as transport nanochannels. The nanotubes are pre-subjected to plasma treatment to increase the surface charge density and transport capacity of the nanochannels, improving the ion selectivity and energy conversion efficiency. Under actual seawater/river water conditions, the developed membrane delivers a power density of ∼5.1 W/m2 and shows good mechanical strength (219 MPa). Our work provides a facile solution to the problem posed by the inability of ideal nanochannels to form membranes independently and paves the way for the application of RED membranes in osmotic energy conversion.

Organic-inorganic composite membrane-based transport membrane condenser: Performance of waste recovery from hot gas mixture of CO2 and water vapor

Recovering the waste heat from the stripped gas (i.e., the gas mixture of CO2 and water vapor) using the transport membrane condenser is an effective approach to reduce the regeneration heat consumption in CO2 chemical absorption process. To decrease the capital expenditure of transport membrane condenser, this study prepared an inexpensive organic–inorganic composite membrane through adding the hydroxylated boron nitride (BN-OH) into the polyvinylidene fluoride (PVDF) during membrane preparation via nonsolvent induced phase separation. Then the composite membrane was placed in a membrane cell as the transport membrane condenser to recovery the waste heat of simulated stripped gas. The results showed that when compared to the single PVDF membrane, the addition of BN-OH improves the pore uniformity, thermal conductivity, and porosity of membrane. Among all the prepared composite membranes, the composite membrane adding 5 wt% nano-sized BN-OH particles exhibits the best waste heat recovery performance. Furthermore, a decrease in the membrane thickness in addition to an increase in polyvinylpyrrolidone dosage during membrane preparation enhances the waste heat recovery performance, however deteriorates the mechanical strength of membrane. Moreover, the organic–inorganic composite membrane prepared in this study demonstrated a good stability of waste heat recovery performance during a long-term operation, showing a potential in the rich solvent-split modified carbon capture process to achieve a low capital expenditure and a high waste heat recovery performance.

High-Toughness and High-Transparency Recyclable Poly(vinyl alcohol)-Based Organic–Inorganic Composite Membranes

High-Toughness and High-Transparency Recyclable Poly(vinyl alcohol)-Based Organic–Inorganic Composite Membranes

The advances development of proton exchange membrane with high proton conductivity and balanced stability in fuel cells

AbstractIn the proton exchange membrane fuel cell, proton exchange membrane (PEM) serves as both the main conductor of protons and the fuel‐blocking membrane. Thus, high proton conductivity and excellent stability are expected for PEMs at the same time. According to chemical structure, this review divides PEM into three groups. Recently, high‐performance PEM has been made possible by controlling chemical structure, organic–inorganic hybrid composite membranes, and nanofiber composite membranes. One of them, nanofiber composite membranes, is distinguished by long‐range order and is capable of achieving both strong proton conductivity with exceptional stability. The high‐performance PEM has been accomplished by the presence of an acid‐rich layer, acid–base interaction, and proton transport channel in PEMs are also summarized in this paper. We believe that our discussion will help the researcher create high‐performance PEM and pave the way for further developments in the field of energy materials as a whole.

Rational design of a flexible inorganic composite membrane with an interconnected porous structure as a high-performance lithium ion capacitor electrode

The synergistic effect of multiple components (Cu, Cu2O and CuO) in CuxONWs and the high bonding strength between the three materials in a CGA membrane anode markedly improve the capacitance and cycling performance of lithium-ion capacitors.

Preparation of high permeance thin-film composite nanofiltration membrane on macroporous ceramic support

Thin-film composite (TFC) nanofiltration (NF) membranes have been widely used in water purification processes. In harsh conditions, however, the application of TFC membrane was limited by selectivity loss because of swelling or dissolution. In this study, a defect-free polyamide (PA) layer was directly prepared on a tubular alumina ceramic membrane with a pore size of 100 nm to compensate these shortcomings. The ceramic support, owing to its superior hydrophilicity, showed excellent affinity with aqueous diamine monomers, preventing defects caused by large pore sizes. Besides, the narrow aperture distribution of support is conductive to control the water-oil interface at an appropriate position that the active layer can form near the support by simple air-drying. Different morphologies and performances were easily obtained by changing the monomer concentration and reaction time. The resulting organic–inorganic composite membrane exhibited pure water permeance of 21.7 LMH/bar and desirable rejection to Na2SO4 of 99.0%. Moreover, the prepared NF membrane showed satisfactory compaction resistance at pressure from 2 to 12 bar owing to the excellent mechanical strength of the support. The inorganic support also endowed the TFC membrane with good performance stability even at 75 °C and after soaking in different organic solvents for one week.

A novel anion exchange membrane based on silicone/polyphenylene oxide with excellent ionic conductivity for AEMFC

AbstractTo achieve good stability of anion‐exchange membranes. We report an organic–inorganic composite anion exchange membrane based on polyphenylene oxide (PPO) and 3‐[2‐(2‐aminoethylamino)ethylamino]propyl‐trimethoxysilane to improve dimensional stability and mechanical stability without affecting ionic conductivity. The successful synthesis of the membranes was confirmed by FT‐IR, 1H NMR, and EDX. The SiOSi three‐dimensional network cross‐linked structure was formed inside the anion‐exchange membranes by added inorganic fillers. It suppressed the swelling behavior of the membrane after water uptake, with water uptake rate of 48.2%–55.6% and swelling rate of 3.1%–14.2%. It improved the mechanical strength of the membranes with tensile strength of 33.5–37.8 MPa as the ratio of the membrane structure varied. Meanwhile, the flexible chain segments in the polymer structure contributed to the formation of microscopic phase separation structures, and the constructed ion‐conducting channels enabled QPPO‐Si‐5 to reach the highest hydroxide ion conductivity of 78.7 mS/cm at 80°C (ion exchange capacity [IEC] value of 1.2 mmol/g). QPPO‐Si‐1 exhibited better long‐term chemical stability, retaining 48.3% of the initial conductivity (30.8 mS/cm) after 600 h of alkali stability testing at 80°C in 1 M KOH solution. In conclusion, the results of this study provide a facile synthetic strategy with improved membrane's comprehensive performance.

Sulfonated Poly(arylene ether nitrile)-Based Composite Membranes Enhanced with Ca2+ Bridged Carbon Nanotube-Graphene Oxide Networks

As the core component of proton exchange membrane fuel cells, proton exchange membranes (PEM) have attracted much attention of researchers. To trade-off the proton conductivity, dimensional stability and anti-oxidation ability of PEM, graphene oxide (GO) and acidized multi-walled carbon nanotubes (MWCNT) using calcium ion as coordination bridge (GO-Ca2+-MWCNT) was synthesized, and then incorporated into sulfonated poly(arylene ether nitrile) (SPEN) to fabricate SPEN/GO-Ca2+-MWCNT organic–inorganic composite membranes by solution-casting method and explore the influence of varying loading on performances as PEM. It was found that the proton conductivity of the composite membranes was higher than that of SPEN, while maintaining better dimensional stability, excellent anti-oxidation ability and good mechanical properties. All of these were attributed to the formation of three-dimensional structure between GO and MWCNT bridged by Ca2+ and the interaction between the sulfonic acid group and calcium ions in SPEN/GO-Ca2+-MWCNT composites. Particularly, the SPEN/GO-Ca2+-MWCNT-1 composite membrane exhibited excellent tensile strength of 71.45 MPa, better thermal stability as well as high proton conductivity (0.054 S/cm at 30 °C, and 0.193 S/cm at 90 °C), above 10–2 S/cm, satisfying the requirement of PEM. All in all, the results indicate that the filler with three-dimensional network structure can effectively improve the performances of SPEN, and the prepared composite membranes show potential applications in many fields.

Poly(ionic liquid)-functionalized graphene oxide towards ambient temperature operation of all-solid-state PEO-based polymer electrolyte lithium metal batteries

Endowing polyethylene oxide (PEO)-based electrolyte with low crystallinity and high efficient Li+ transport channels is urgently required for next generation all-solid-state lithium metal batteries (LMBs). Herein, a new type of oxyethyl containing poly(ionic liquid) modified graphene oxide nanoparticles (ox-PIL@GO) is coincidentally proposed for preparing PEO based organic–inorganic composite electrolyte membranes (CPEs). Both experimental and DFT simulation results indicate that the dissociation of the LiTFSI is significantly enhanced by the anticipated electrostatic interaction between imidazolium cation and TFSI- anions in CPEs. In addition, the formed electrostatic interaction can also inhibit the movement of TFSI-, giving rise to the increased lithium transference number of 0.61 from 0.21 for the neat PEO/LiTFSI electrolyte. Furthermore, the ion–dipole interaction between imidazolium cation and PEO chain largely reduces the crystallinity of PEO and the ionic conductivity of 1.01 × 10-4 S cm−1 at 40 °C is successfully obtained. As a result, the ox-PIL@GO incorporated PEO electrolyte enables the Li||Li symmetric cell with long-term, square-wave galvanostatic cycling test of 800 h at current density of 0.1 mA cm−2 at 50 °C and the solid-state LiFePO4|CPE|Li battery with high discharge specific capacity of 116 mAh g−1 at 40 °C at 1C for 300 cycles.

Synthesis and preliminary gas permeation properties of vitreous composite clinoptilolite membranes

In this study, we communicate our initial findings regarding the development of novel inorganic composite clinoptilolite membranes. The membranes were formed from natural clinoptilolite microparticles sintered together using specialty glass atop a porous Al2O3 porous disk that was used as a support. Fourier transform infrared spectroscopy and x-ray diffraction analysis was used to confirm that the natural clinoptilolite used in this study maintains its overall structural conformation following heat treatment as high as 1073 K. Surface and cross-sectional scanning electron microscopy imagery of the prepared membranes showed the formation of a porous clinoptilolite – glass composite layer and a mostly glass layer with lesser porosity. Single gas He, CO2, CH4, and N2 permeation experiments were carried out to evaluate the initial performance parameters of the membranes. Single gas membrane permeation decreased with increasing amount of glass, and ranged from 2 × 10−7 mol/m2s Pa for the membrane prepared with 30 wt. % clinoptilolite as filler to as high as 4 × 10−6 mol/m2s Pa for the 50 wt. % clinoptilolite membrane. The ideal selectivity was calculated from the single gas permeance for potential natural gas or biogas CH4/N2 and CO2/CH4 separations. These values were the highest at 1.7 ± 0.2 and 1.9 ± 0.1 for the membranes prepared with 40 wt. % and 30 wt. % clinoptilolite, respectively. Considerable refinements to this technique are necessary in order to minimize the presence defects before it may be used as an alternative to inorganic membranes or mixed matrix membranes as an approach when zeolite crystallization is difficult to achieve.

Distillation-pervaporation membrane hybrid system for epichlorohydrin and isopropyl alcohol recovery in epoxy resin production process

Epoxy is a widely used thermosetting resin that exhibits good mechanical strength, chemical resistance, and dimensional stability. In order to manufacture this resin, isopropyl alcohol (IPA) and excess epichlorohydrin (ECH) are used as a solvent and an indispensable raw material, respectively. However, ECH and IPA form a ternary azeotropic mixture in the presence of water, rendering it difficult to separate the materials with high purity via distillation. Therefore, a hybrid of pervaporation (PV)-coupled distillation was attempted to improve the epoxy manufacturing process. Silica-zirconia composite membranes were prepared by coating the α-Al2O3/SiO2-ZrO2 intermediate layer and the SiO2 separation layer, i.e., dip-coating was performed on the α-Al2O3 support and subsequently applied to the hybrid process. When the pervaporation process of distillate get from the epoxy by-product was applied, H2O selectivity for IPA/ECH was 15–30 and for H2O/aqueous impurities was 8–54, indicating that H2O for H2O/aqueous impurities permeated relatively faster than IPA/ECH. Therefore, pervaporation coupled distillation using an inorganic composite membrane was feasible for the selective removal of H2O/aqueous impurities in epoxy by-product mixture obtained from epoxy manufacturing.

Low-cost and facile synthesis of geopolymer-zeolite composite membrane for chromium(VI) separation from aqueous solution

Inorganic membranes in wastewater treatment have captured increasing attention due to their numerous advantages. However, high cost and complicated producing process restricted their benign developments. This study proposed an novel inorganic geopolymer-zeolite composite membrane which was synthesized by using circulating fluidized bed fly ash (CFBFA) solid waste as initial material and via a low-cost and facile geopolymerization-hydrothermal treatment processes, further, the membrane was employed to separate Cr(VI) ion from aqueous solutions. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectra results indicated that geopolymer-zeolite (Li-ABW) composite membrane was obtained successfully. Field emission scanning electron microscopy (FESEM) results demonstrated that the membrane had a compact zeolite layer with thickness about 1.5 μm. The effects of transmembrane pressures (TMP), Cr(VI) concentration, pH, ionic strength, and co-existing ions on Cr(VI) rejection were investigated, and the results revealed that the Cr(VI) rejection reached 85.45 % under 10 kPa of TMP, 1000 mg L−1 of Cr(VI), and pH 7. The separation mechanism of Cr(VI) on the geopolymer-zeolite composite membrane was considered to be size exclusion and electrostatic interaction. These results suggested that the geopolymer-zeolite composite membrane had a potential application for the effective removal of Cr(VI) contaminants from wastewater.

An ion-conductive Li7La3Zr2O12-based composite membrane for dendrite-free lithium metal batteries

Lithium (Li) metal is pursued as the anode for next generation lithium batteries because of the highest energy density and the lowest reduction potential. However, the formation of lithium dendrite caused by nonuniform Li deposition exists. Moreover, the safety issue arising from hazardous Li dendrites hinders the practical application of lithium metal batteries (LMBs). In this work, an organic and inorganic composite protective membrane (CPM) consisting of PVDF-HFP and LLZO particles is prepared by a simple tape-casting method. The CPM modified Li symmetric cell exhibits no obvious voltage hysteresis over 500 h at 2 mA cm−2 and 1 mAh cm−2. Moreover, the CPM modified Li | LFP cell can stably run 800 cycles at 1C and retain a high average Coulombic efficiency of ~99.95%. Moreover, the in-situ formation of LiF between metallic Li anode and the C–F group in PVDF-HFP exhibits high modulus, effectively suppressing the growth of lithium dendrites. The uniform Li deposition is achieved owing to the high ionic conductivity and Li+ transference number of CPM. In addition, the high modulus LiF layer can stabilize interface and greatly reduce interfacial resistance after cycling.

Recent progress in molecular engineering to tailor organic–inorganic interfaces in composite membranes

Recent advances in molecular engineering of organic–inorganic composite membranes are presented.

The Investigation of Thermodynamic and Kinetic Effects in TiO2/Al2O3/ PVDF Composite Membrane Forming Process

Background: The addition of inorganic nano dioxide (TiO2) and alumina (Al2O3) particles into the organic polymer material Polyvinylidene Fluoride (PVDF) can enhance the composite membranes’ hydrophilicity and anti-pollution capacity in the water treatment process. Objective: The study aimed to investigate thermodynamic and kinetic effects of the inorganic nanoparticles on composite membrane in the membrane forming process. Method: The turbid point titration method was adopted to determine casting solution phase separation point of the system and draw ternary phase diagrams. Ternary system phase diagrams were used to investigate the thermodynamic effects of nanoparticles on the membrane forming process. UV spectrophotometer transmittance decline curves of the casting solution system added different amounts of nanoparticles were measured in order to investigate the kinetic effects of nanoparticles in the membrane forming process. Results: The results show that nanoparticles have a very high specific surface area, which can make strong adsorption of PVDF polymer chain and reduce the cohesive energy of the polymer in the casting solution. The membrane forming system is more prone to phase separation, thereby reducing the sedimentation values of the phase separation point. The casting solution system becomes unstable thermodynamically. The decreasing trend casting solution system and precipitation values is obvious in the range of 1% to 3% nanoparticles content and this trend weakens when nanoparticles content is 4%. Nanoparticles can decrease the ability of non-solvent to accommodate in the casting solution and make membrane form in smaller non-solvent concentration. The hydrophilic nanoparticles in the casting solution can affect mass transfer resistance of the solvent and non-solvent and augment mass transfer driving force for mutual diffusion of the solvent and non-solvent thus shortening the membrane forming time from the casting solution being immersed in the gelation bath for membrane formation. In the system with PVP as pore-forming agent, the process takes about 800s without nanoparticles addition and about 600s to complete the process after adding the nanoparticles. Conclusion: The addition of nanoparticles reduces the cohesive energy of the polymer in the casting solution, the casting solution becomes unstable in thermodynamics; The addition of nanoparticles increases the mass transfer force by bidirectional diffusion of solvent and non-solvent in the casting solution.

A Review on Inorganic Nanoparticles Modified Composite Membranes for Lithium-Ion Batteries: Recent Progress and Prospects.

Separators with high porosity, mechanical robustness, high ion conductivity, thin structure, excellent thermal stability, high electrolyte uptake and high retention capacity is today’s burning research topic. These characteristics are not easily achieved by using single polymer separators. Inorganic nanoparticle use is one of the efforts to achieve these attributes and it has taken its place in recent research. The inorganic nanoparticles not only improve the physical characteristics of the separator but also keep it from dendrite problems, which enhance its shelf life. In this article, use of inorganic particles for lithium-ion battery membrane modification is discussed in detail and composite membranes with three main types including inorganic particle-coated composite membranes, inorganic particle-filled composite membranes and inorganic particle-filled non-woven mates are described. The possible advantages of inorganic particles application on membrane morphology, different techniques and modification methods for improving particle performance in the composite membrane, future prospects and better applications of ceramic nanoparticles and improvements in these composite membranes are also highlighted. In short, the contents of this review provide a fruitful source for further study and the development of new lithium-ion battery membranes with improved mechanical stability, chemical inertness and better electrochemical properties.

A Novel Metal–Organic Framework (MOF)–Mediated Interfacial Polymerization for Direct Deposition of Polyamide Layer on Ceramic Substrates for Nanofiltration

AbstractA facile metal–organic framework (MOF)‐mediated interfacial polymerization (IP) method is developed to prepare a polyamide (PA) layer directly on the ceramic substrate for nanofiltration. MOF is introduced to connect ceramic substrate and PA layer via chemical bonding, resulting in a robust separation layer. The optimization of IP can be controlled by MOF growth process via tuning the surface roughness as well as hydrophilicity. This method will provide a new way for the preparation of next generation of organic–inorganic composite membranes.

Composite inorganic anion exchange membrane for electrodialytic desalination of milky whey

Composite membranes have been obtained by modification of macroporous ceramics with hydrated zirconium dioxide and basic bismuth nitrate. The modification technique provided formation of the two-component modifier directly in macropores of the inorganic matrix. This method allows us to obtain the material, which possesses by optimal combination of charge selectivity and electrical conductivity, by means of one-time modification. It is assumed that nanoparticles of basic bismuth nitrate (5 nm) block pores between larger particles of hydrated zirconium dioxide (several tens of nanometers) providing semipermeability of the membranes towards anions in acidic media: potentiometric transport number of counter-ions (Cl-) reaches 0.9. Electrodialytic desalination of milky whey has been carried out using a pair of polymer cation exchange (Nafion 117) and composite inorganic membranes. The possibility of whey desalination under overlimiting current has been shown. The current efficiency due to anions reaches 80% under these conditions. Electrodialysis of whey allows us to remove 75 % of the mineral components in 3 h, the same purification degree is achieved in 30 min for nanofiltration permeate.

Self-repairing mechanism and surface characterization of compressor vanes lubricated with oil added with magnesium silicate hydroxide nanorods

Using magnesium silicate hydroxide as additive of lubricating oils for reducing friction in engineering equipment/machinery has been researched intensively. However, some mechanism relating to the growth of the self-repairing layers on the won surfaces is still not clearly explained. At the same time, using magnesium silicate hydroxide (MSH) in the form of nanorods showed great promise in reducing friction and wear. In this study, surface-modified MSH in the form of nanorods was used as additive of polyolester oil (POE) which was then used for the lubrication of compressor vanes. The sample parts were studied on the morphology and the microstructure of the self-repairing layer in a great depth. The results showed that self-repairing layers with different thicknesses were generated on the worn surfaces when the POE with 1 wt.% nanorods-MSH was used. It was found that the self-repairing layers consist of organic–inorganic composite membranes, and with increase of working time of the compressor vanes, the self-repairing layers become denser and thicker, while their micro-structural form remains to be similar. The situ-repairing capability of the metal surfaces (roller-vane pair of the compressor) enforced by the MSH nanorods is very significant, indicating high potential for industrial applications where boundary and mixed lubrications are needed.

Preparation and characterization of PES-xerogel nanocomposite ultra-filtration membrane

Organic–inorganic composite ultrafiltration membrane was prepared with Polyethersulphone and nano-xerogels. On the other hand, xerogels were also prepared by a simple method and were synthesized by a sol–gel process in which tetramethyl orthosilan and tetraethyl orthosilan were used as a precursor. Besides, high-energy planetary ball mill process was applied to make the nano-xerogels. Then, the final nano-xerogels were used to prepare ultrafiltration membrane. Modified membranes showed significant changes in physical and chemical properties. The presence of nano-xerogel in the membrane structure improved the hydrophilicity of the membrane. Pure water flux and the pore size of the membranes increased significantly. The result showed that BSA rejection of modified membranes is high. The membrane with 2 wt% of TEOS xerogel proved to have higher BSA rejection.