Nanoporous Ceramic Membranes Research Articles

Bioinspired Solar-Driven Osmosis for Stable High Flux Desalination.

The growing global water crisis necessitates sustainable desalination solutions. Conventional desalination technologies predominantly confront environmental issues such as high emissions from fossil-fuel-driven processes and challenges in managing brine disposal during the operational stages, emphasizing the need for renewable and environmentally friendly alternatives. This study introduces and assesses a bioinspired, solar-driven osmosis desalination device emulating the natural processes of mangroves with effective contaminant rejection and notable productivity. The bioinspired solar-driven osmosis (BISO) device, integrating osmosis membranes, microporous absorbent paper, and nanoporous ceramic membranes, was evaluated under different conditions. We conducted experiments in both controlled and outdoor settings, simulating seawater with a 3.5 wt % NaCl solution. With a water yield of 1.51 kg m-2 h-1 under standard solar conditions (one sun), the BISO system maintained excellent salt removal and accumulation resistance after up to 8 h of experiments and demonstrated great cavitation resistance even at 58.14 °C. The outdoor test recorded a peak rate of 1.22 kg m-2 h-1 and collected 16.5 mL in 8 h, showing its practical application potential. These results highlight the BISO device's capability to address water scarcity using a sustainable approach, combining bioinspired design with solar power, presenting a viable pathway in renewable-energy-driven desalination technology.

Functionalized Nanoporous Ceramic Membranes for Electrodialysis Treatment of Harsh Wastewater

INTRODUCTION Electrodialysis (ED) is a well-developed technology for electrochemical desalination. However, many industries generate harsh wastewater streams that are incompatible with traditional ion exchange membranes and thus limit the use of ED. Membrion® has developed novel ceramic-based ion exchange membranes which offer a number of advantages over traditional polymer membranes: high performance in low pH, chemical resistance to oxidizers, and a rigid structure which minimizes membrane swelling. This presentation will discuss these novel membranes and their performance in electrodialysis stacks. EXPERIMENTAL Novel ceramic ion exchange membranes (IEM) are synthesized with patented silane-based sol-gel techniques. These ceramic membranes have covalently bound charged moieties similar to polymer IEMs; however, they are attached to a tunable nanoporous structure. The pore size, shape, and network structure are engineered through a molecular self-assembly process where thermodynamic driving forces are used to direct where and how pores form. Either cation (e.g., SO3 -) or anion (e.g., NH4 +) groups can be added within the membrane nanopore structure to enhance ion selectivity. The ceramic IEMs are produced on a roll-to-roll manufacturing line with low temperature processing. Membrane performance is assessed by measuring permselectivity (PS), area-specific resistance (ASR), and batch electrodialysis tests. RESULTS Figure 1 shows that both cation exchange membranes (CEM) and anion exchange membranes (AEM) show a decreased ASR compared to traditional polymer membranes, while maintaining comparable PS (i.e., the ability to separate cations and anions). The lower ASR of ceramic membranes is advantageous, as this can improve the overall energy efficiency of electrodialysis desalination. We maintain good performance (i.e., comparable current efficiency and water recovery) when integrated into a 10-cell pair stack. Most significantly, the right plot of Figure 1 shows a stable dilute water recovery of ~90% achieved with ceramic membranes after being stored in solutions ranging from pH 3 to pH 0 for 30 days. We have also demonstrated this technology in the field with copper wastewater generated at a microelectronics manufacturing facility. On site bench and pilot testing showed that our membranes could be used to nearly eliminate the copper sent to single-use IEX resin. DISCUSSION Ceramic-based ion exchange membranes are able to achieve comparable performance to traditional polymer membranes and offer some unique advantages. Long exposure to very low pH has negligible impact on ceramic ED stack performance. Additionally, we have observed stable performance in the presence of strong oxidizing agents such as hydrogen peroxide. This stability is expected, as the silica backbone of these materials is already in a fully oxidized state, as opposed to traditional polystyrene-based membranes. This data suggests ceramic membranes could be an ideal solution for acidic and/or oxidizing wastewater streams found in industries such as semiconductor manufacturing and mining. In addition to offering chemical stability in harsh environments, the patented silica sol-gel process used to cast these membranes is extremely tunable. Through incorporating commercially available functionalized silanes, the pore size and chemical make-up can be easily altered to target specific waste streams. CONCLUSIONS Ceramic ion exchange membranes are shown to have similar performance attributes to traditional polymer IEMs when evaluated for electrodialysis water purification applications. The good stack-level performance combined with stability in harsh environments have the potential to dramatically broaden the use of ED/EDR for industrial wastewater treatment. Figure 1

Facile fabrication of ceramic-based highly permeable composite nanofiltration membranes by in-situ interfacial polymerization

The preparation of thin-film composite (TFC) membranes with both extraordinary permeance and excellent rejection performance are still a challenge due to the irreversible and rapid interfacial polymerization (IP). The high reactivity of amine monomers helps to form a defect-free membrane instantaneously during the IP process, but also ultimately leads to low water permeance. Here, a facile strategy was proposed to improve the performance of TFC membrane by conducting in-situ IP on the nanoporous ceramic membranes. First, it was confirmed that the hydrophilic ceramic membrane, which serves as an oil-water interface, can provide a uniform aqueous layer. The free-like interface is conductive to the formation of defect less polyamide layer even at ultra-low monomer concentrations and very short reaction times. Then, the performance of TFC membranes using ceramic membranes with different pore sizes as supports was systematically investigated. The result indicates that supports with smaller pore size and narrower distribution enable facilitate the formation of a thinner membrane. Moreover, the nanofiltration membrane exhibited ultra-high pure water permeances of 42.9 LMH/bar and a rejection of 93.4 % to Na2SO4, utilizing a ceramic membrane with a pore size of 10 nm as support under PIP of 0.025 wt% and reaction times of 10 s.

Numerical investigation of water and heat recovery from flue gas by using nanoporous ceramic membrane tubes

Direct emission of high humidity flue gas results in great wastage of water and thermal energy. Ceramic membrane technology has been widely regarded as a potential technology for water and heat recovery from flue gas. This study presents numerical investigations of water and heat recovery processes from flue gas by using nanoporous ceramic membrane tubes (CMTs). A comprehensive mathematical model is developed based on the Kelvin equation, and the Hagen–Poiseuille equation is applied to calculate the bilateral pressure difference needed for continuous recovery operation. Decreasing the pore size of the separation layer of the ceramic membrane improves the capillary condensation flux but also drastically increases the required bilateral pressure difference. CMT with a pore size of 20 nm is appreciated for the studied conditions. The performances of the CMTs located in the last rows along the flow direction are limited by local low gas temperature and humidity. Twelve rows of tubes are suggested to be arranged along the gas flow direction for ceramic membrane devices with pore sizes of 20 nm and higher. A low transverse spacing obviously improves the overall water and heat recovery efficiency of the device, decreases the performance of each tube, and enhances the gas flow resistance. A transverse spacing ratio of less than 1.4 is suitable for the studied conditions. A combined arrangement by substituting the tubes located in the last rows with those of smaller pore size is a better method than using uniform tubes. The device with combined 20 and 10 nm CMTs is suggested for the studied conditions.

Application of nanoporous ceramic membrane derived from Fe/S/Si/Al/O-rich mining solid waste in oil–water separation and heavy metal removal of industrial high concentrated emulsifying wastewater

Ceramic membranes are widely used in industrial wastewater treatment due to their excellent chemical stability, thermal stability, high oil cut-off rate, and long-term recyclability. However, its application range is limited because of the high price of commercial ceramic membranes. In this study, a low-cost environment-oriented ceramic membrane was prepared from gold mine tailings and SiO2-rich granite waste slag by sintering method. The Fe/S/Si/Al/O enriched ceramic membrane prepared by sintering in an atmospheric atmosphere was beneficial to the application of oil–water separation and heavy metal removal of industrial high concentrated emulsifying wastewater. At lower sintering temperature (1000 ℃), adding 33.3% gold tailings (M3), the membrane had good oil cut-off performance (96.1%) and stability. 29.47 MPa mechanical strength and 2.75% mass loss of 1000-M3 was confirmed under extreme acidic and alkaline conditions, and even in high-temperature environments, the mass loss was only 2.5%. After 16 cycles of performance test, the oil cut-off rate only decreased by 0.01%. The developed membrane exhibited good chemical stability and thermal stability. Based on the analysis of membrane contamination behavior, the ceramic membranes prepared could restore nanoporous channels only by ultrasonic treatment. In addition, 100% removal performance of iron and copper was obtained, and 78.6% removal efficiency was achieved for Chromium and cadmium. These fascinating characteristics make the novel ceramic membrane an excellent candidate with a high oil–water separation ability. More importantly, the inexpensive materials from recyclable solid waste and low-energy consumption preparation technique make it possible to scale up production. Thus, the as-prepared nanoporous ceramic membrane prepared from gold mine tailings with biological toxicity as hazardous waste has the potential of waste resource utilization for treating industrial grade high load emulsion wastewater.

Fouling behavior of nanoporous ceramic membranes in the filtration of oligosaccharides at different temperatures

• High temperatures promote more severe membrane fouling by oligosaccharide filtration. • Pore blocking readily occurs at high temperatures during filtration of oligosaccharides. • Cake layer formation is the dominant fouling mechanism at low temperatures. • Membranes with narrow pore size distribution can resist high-temperature pore blocking. Linearly-structured, elastic, and unevenly distributed oligosaccharides affect the durability of membranes owing to fouling. High temperatures are often employed to improve the efficiency and reduce microbial growth in membrane filtration, making it more challenging to address membrane fouling. In this study, the fouling behavior of nanoporous ceramic membranes by oligosaccharides at different temperatures was systematically investigated. The resistance-in-series model and Hermia’s models suggested that the cake layer was the primary source of membrane fouling at low temperatures, whereas the additional occurrence of pore blocking at high temperatures contributed to a higher extent of membrane fouling. The elastic deformation of oligosaccharides at high temperatures led to the filling of membrane pores, which was the key factor contributing to a deterioration in the filtration performance. In this case, the matching relationship between the pore size distribution of the membrane and molecular weight distribution of the oligosaccharides was a critical factor when analyzing pore blocking. Small pores and a narrow pore size distribution could resist high-temperature pore blocking. This study provides fundamental insights into membrane fouling caused during the filtration of oligosaccharides, specifically at high temperatures. The findings will also aid in the development of advanced anti-fouling strategies for membrane filtration.

Photocatalytic anti-biofouling performance of nanoporous ceramic membranes treated by atomic layer deposited ZnO

Biofouling caused by microorganisms is a critical problem in membrane treatment systems. In this study, we immobilized a highly photocatalytic active thin ZnO film on the surface of a nanoporous ceramic membrane using atomic layer deposition (ALD). Through a series of membrane characterizations, we confirmed that ALD ZnO is successfully deposited uniformly along the inner surface of the nanopores in the active layer of the membrane as desired. Additionally, the ALD ZnO-treated ceramic membrane exhibited excellent photocatalytic activity with a ZnO thickness of 36.5 nm under 1 mW/cm2 of UV-A light irradiation. Compared to the bare ceramic membrane, the ALD ZnO-treated membrane with UV-A irradiation showed higher anti-biofouling efficacy. We propose that reactive oxygen species generated from ZnO may impede microbial initial adhesion, thus inhibiting biofilm formation. However, with high irradiation intensity of UV-A, water flux decreased owing to membrane pore constriction, although no significant biofilm formation was observed. Nevertheless, the proposed ALD ZnO treatment on the nanoporous ceramic membrane is expected to provide a promising novel approach for effective prevention of biofouling in membrane-based processes.

Synthesis of nanoporous ceramic materials for filtration of liquids and gases by technological combustion method

Experimental and analytical studies on the synthesis of a Ti-Al-based ceramic material with a nanoscale porous structure were conducted. The results of previous studies conducted by the authors showed that it is reasonable to obtain porous ceramic materials designed for filtration of liquids and gases by thermal explosion (throughout the sample) rather than by layer-by-layer combustion. Self-propagating high-temperature synthesis (SHS) was used to obtain nanoporous ceramic membranes from a mixture of powders, wt.%: 40Ti + 60Al in one stage with the TiAl3 formation. It was found that the synthesized material consists of the main phase TiAl3 with a small amount of aluminum oxidized into Al 2 O 3 and unreacted. The microstructural analysis of the sample fracture showed that the resulting material has a developed surface and high open porosity. Empirically investigated open porosity is up to 48%, and the pore size ranges from 0.1 to 0.2 цт. The efficiency of the porous material obtained for the Ti-Al-based ceramic SHS filter reaches 99.999 %, gas flow resistance is 100 mmHg, filtration index is 0.062. Gas ultrafiltration capacity is up to 40 l/(cm 2 •h) at a pressure drop on the filter of 2 kPa, and water ultrafiltration capacity ranges from 2 to 10 l/(cm 2 •h) at a pressure drop on the filter of 0.1 MPa. Membranes made of ceramic materials with a gradient nanoporous structure by this method can be used as filter elements for small units providing fine water cleaning from bacteria, viruses, dissolved organic carbon, as well as for fine cleaning of air, process gases from dispersed micro-impurities and radioactive aerosols. The membrane SHS filters developed can also be used in units operating in aggressive environments and/or at high temperatures (up to 1000 °C).

Facile pore size tuning and characterization of nanoporous ceramic membranes for the purification of polysaccharide

Developing nanoporous ceramic membranes with tunable pore structure offers a new paradigm to the precise separation and purification of functional polysaccharides. Here, a facile in-situ chemical deposition method was applied to obtain nanoporous ZrO2 membranes with controllable pore size. A modified rejection curve method based on Poiseuille flow, Ferry's equation, and log-normal distribution was proposed to calculate pore size distribution of membrane. The results showed that with the increase of precursor content from 0 to 20 wt%, the geometric mean diameter of ceramic membranes decreased from 5.9 nm to 3.1 nm, corresponding to a significant decrease of molecular weight cut-off from 15.0 kDa to 3.3 kDa. Still, the pure water permeability was maintained at a high level of about 42 L m−2 h−1·bar−1. Meanwhile, the geometric standard deviation decreased from 1.20 to 1.16, indicating a narrower pore size distribution. The obtained nanoporous ZrO2 membrane performed a high rejection of dextran, while the fructose can be effectively and efficiently separated with a separation factor as high as 11.5, therefore enlarging our choices removing fructose from dextran.

Experimental study on differences of heat and mass flux on opposite side of a 10-nm nanoporous ceramic membrane tube

A nanoporous ceramic membrane tube (CMT) is able to extract water vapor and latent heat from gas mixture, such as flue gas exhausted from thermal power plant, because of its excellent permselectivity and heat-exchange capacity. However, due to the effect of the gravity force on condensation film formation and condensate permeation process, the water and heat-recovery performance on top and bottom parts of a horizontal CMT may be distinct. In this study, a corresponding experiment was performed to verify and research the phenomenon by installing six equidistant and symmetrical measuring points at top and bottom parts of the experimental CMT module, respectively. According to the experimental data, the local temperature of cooling water on top (Tc,l,t) and bottom (Tc,l,b) parts of CMT module exhibited a distinct changing tendency, and the maximum temperature difference (ΔTc) could approach 2.68 °C. Typically, the effects of gravity force on condensation film was negligible, while the permeation capacity of condensate was influenced by gravity force apparently. Moreover, most of condensate (92.24% maximally) was generated during the normal condensation process, merely a small proportion of condensate was produced by the capillary condensation process. This paper is useful for horizontal membrane type gas-water technology improvement.

A safe quasi-solid electrolyte based on a nanoporous ceramic membrane for high-energy, lithium metal batteries

The use of lithium metal as the anode for Lithium Metal Batteries (LMB) requires having solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Here we reported on a hybrid electrolyte membrane based on nanostructured yttria-stabilized-zirconia, sintered by means of High Pressure-Field Assisted Sintering Technique (HP-FAST) in order to retain proper nano-porosity, and activated with a standard LiPF6-EC-DMC solution. By a thorough physico-chemical and functional characterization, we demonstrated that the liquid is effectively nano-confined in the ceramic membrane, and the resulting quasi-solid electrolyte is non-flammable. A remarkable conductivity value of 0.91 mS cm−1 was observed at room temperature, with activation energy of 0.2 eV, and cation transference number, t+ = 0.55, substantially higher than that of the pure liquid electrolyte. The hybrid electrolyte showed electrochemical stability up to 5.5 V vs. Li+/Li, and excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. A full cell Li/electrolyte/LiMn2O4 showed more than 90 mAh g−1 at 2C for more than 120 cycles. These very promising results indicated that nano-porous ceramic hybrid electrolytes may be conveniently used in LMB.

Ultrasound Assisted Synthesis of Size-Controlled Aqueous Colloids for the Fabrication of Nanoporous Zirconia Membrane.

Permeation and separation efficiency of ceramic membranes are strongly dependent on their nanoporous structures, especially on the pore size. In this work, ultrasound is employed to form the size-controlled ZrO2 nanoparticles, and a ceramic membrane is prepared with tunable pore size. Under the ultrasound treatment, H+ from water plays a key role in the synthesis process. The cavitation caused by ultrasound promotes the hydrolysis of the precursor in water, which produces a large number of H+. These H+ will react with precipitant added and generate cyclic tetrameric units. Excess H+ can peptize cyclic tetrameric units and form an electrical double layer, resulting in a stable sol. Unlike ultrasound treatment, precipitant will react directly with the precursor and generate precipitation if there is no ultrasound added. Moreover, cavitation is good for the dispersion of cyclic tetrameric units. The particle size of Zr-based colloidal sol can be tuned in the ranges of 1.5 to 120 nm by altering the molar ratio of precursor to precipitant, ultrasonic power density and radiation time. Meanwhile, ultrasonic power density and radiation time have effects on grain size and the crystalline transition temperature of particles which influence performance of the ceramic membrane. As a result, membranes exhibit high performance together with high permeability and desirable rejection. To develop such a simple and controllable method for tuning particle size is extremely important in the preparation of nanoporous ceramic membranes.

Contrastive research of condensation-heat-transfer and water-recovery performance on 10-nm ceramic membrane tube and stainless steel tube

As a new type of condensation-heat-transfer facility, nano-porous ceramic membrane tube is surrounded by nano-porous wall surface, which is hydrophilic to capture the vapor or condensate. In general, water vapor will condense into liquid near the wall surface or inside its nano-sized pores, wherein its latent heat will be released synchronously. Thus, an amount of heat and water can be recovered by using nano-porous ceramic membrane tube. Experiments are performed using a 10-nm ceramic membrane tube and a traditional condensation-heat-transfer tube (a 304 stainless steel tube in the experiment) with the same dimensions. The gas mixture consisting of nitrogen (N2) and water vapor is employed as working fluid, and the low-temperature water is used as the cold source. Great attention is paid to contrastively evaluate the heat-transfer and water-recovery performance of two kinds of tubes at different influential parameters (e.g., inclination angle). Compared with stainless steel tube, ceramic membrane tube has a more outstanding heat-transfer characteristic; it can enhance the cooling water temperature by 125% maximally. In addition, condensation-heat-transfer process of 10-nm ceramic membrane tube is influenced by inclination angle more significantly. In the 10-nm ceramic membrane tube, it has highest condensation-heat-transfer coefficient at horizontal flow (θ = 0°) and lowest at vertical down flow (θ = − 90°). Finally, water-recovery mass flux in the 10-nm ceramic membrane tube is higher than that in stainless steel tube, especially for the transmembrane pressure difference is higher than 3.83 kPa. This paper is useful for ceramic membrane condenser arrangement and design.

The investigation of desulphurization and water recovery from flue gas using ceramic composite membrane

Using nanoporous ceramic composite membranes to remove sulphur dioxide and to recover water vapor in flue gas is a new method, and this paper studied the effects of sulphur dioxide on the water recovery process. In this study, the outer-side coating of hollow nanoporous ceramic composite membrane is selected as the study object. In the membrane module for desulphurization, one end of membrane is closed to create the high-pressure environment inside membrane to ensure that the cooling water in the membrane penetrates the outer surface of the membrane to form a stable water film which can absorb sulphur dioxide from flue gas. In the membrane module for recovering water, using a vacuum pump to create micro-negative pressure environment inside membrane, and then water vapor and condensate can penetrate through the membrane under pressure difference. Based on the ceramic composite membrane module, an integrated experimental platform for desulphurization and water recovery is constructed, and the mathematical model for predicting water recovery performance is established. According to the experimental and theoretical results, the mathematical model can predict the water recovery performance of the ceramic composite membrane.

Reducing CO2 regeneration heat requirement through waste heat recovery from hot stripping gas using nanoporous ceramic membrane

In CO2 chemical absorption process, bypassing the unheated rich solvent before the lean/rich heat exchanger to recover the waste heat of the stripping gas (i.e., rich-split process) can reduce CO2 regeneration heat requirement. In this study, we introduce the hydrophilic mono-channel tubular ceramic membranes for recovering the waste heat from stripping gas using CO2-rich monoethanolamine (MEA) solvent. Heat recovery performance (qrec) of the ceramic membrane heat exchanger (CMHE) is systematically investigated with various operating parameters. Results show that an increase in the rich solvent flow rate can lead to a great increase of qrec value, however may inversely generate a higher CO2 regeneration heat consumption than that w/o rich-split process, particularly at higher solvent flow rates. So the flow rate of bypassed rich solvent in CMHE should be optimized. Meanwhile, increasing the water vapor molar fraction or the inlet stripping gas pressure can increase qrec value as well. Additionally, it is mandatory to reduce the temperature of cold rich solvent because its increase can generate the great drop of qrec value. Furthermore, the CMHE with 4 nm mean pore size of the separation layer of the ceramic membrane performs better than 10 nm CMHE in terms of qrec value, meaning the required membrane area of 4 nm CMHE is 14.9–60.54% smaller than 10 nm CMHE for recovering the same waste heat. The mass transfer of MEA and CO2 can be neglected due to the blocking effect of the condensate in the membrane nanopores. To allow the heat transfer data readily utilized, the empirical correlations with high accuracy for predicting qrec are proposed for 4 nm and 10 nm CMHEs.

Experimental study on differences of heat and mass flux between 10- and 50-nm pore-sized nano-porous ceramic membranes

In this study, the experiment compares the thermal and water-recovery performance of the 10- and 50-nm pore-sized ceramic membrane tubes. The gas mixture consisting of water vapor and nitrogen gets thorough the ceramic membrane tube, and the cooling water flows along the tube exterior surface. The feed gas velocity (Ub,in) at the entrance was changed from 4 to 8 L/min and the inlet temperature (Tb,in) was increased from 323 to 353 K. What’s more, the cooling water (Uc,in) velocity at the entrance was 1, 1.5, and 2 L/min respectively. In conclusion, the performance of heat and mass transfer in the 10-nm pore-sized membrane tube is more remarkable than that in 50-nm pore-sized membrane tube. Additionally, the efficiency of water recovery in the two kinds of ceramic membrane tube increases with the increasing of Tb,in and Uc,in, while it decreases with the increasing of Ub,in. The capabilities of gas adsorption and thermal conduction are influenced by surface area of membranes, which can be attributed to the difference of heat and mass-transfer process between the 10- and 50-nm pore-sized ceramic membrane tubes.

Flexible Ceramic Membranes for Redox Flow Batteries

Grid-scale power storage remains one of the largest challenges to wide-spread adoption of clean energy technologies with intermittent energy sources (e.g., solar, wind and tidal). Redox flow batteries (RFB) are an environmentally friendly and scalable technology with the potential to meet this need. However, ion exchange membranes that are crucial to battery performance are expensive, lack chemical stability in a strong oxidizing environment, and/or have poor ion selectivity which leads to electrolyte diffusion across the membrane and performance instability. These issues have limited commercial flow battery manufacturers to two options: 1) perfluorocarbon membranes - which are chemically robust and moderately ion selective but very expensive, or 2) separators - which are cheap but chemically degrade over time and have poor ion selectivity. In this paper, we discuss the design and scale-up of a novel, nanoporous ceramic flow battery membrane that is chemically robust, ion selective and inexpensive enough to reduce the total production cost of commercial flow batteries by > 15%. In this work, we investigate the use of a primarily inorganic membrane created using sol-gel processing of silicates without calcination or sintering. Silica is an advantageous material for membranes because of its excellent chemical stability and extremely low cost. Furthermore, the gelation process can be utilized to tune the pore size for effective size exclusion of electrolytes (i.e., good ion selectivity). In this study, small angle x-ray scattering (SAXS) was utilized to characterize the membrane pore structure. Model fitting can be utilized to extract the porosity as well as pore shape, size and size distribution. By varying the gelation conditions, average pore radii were found to be in the range of 0.4 – 2 nm. This pore structure is nearly ideal for vanadium-based RFBs given that pores must be able to effectively transport protons (radius of 0.25 nm) but not vanadium ions (radius of 0.5 nm). Proton conductivity and vanadium permeability were also determined and shown to be identical to an industry standard perfluorocarbon membrane (i.e., Nafion 212). Variation in membrane nanostructure was directly correlated to performance. Furthermore, on-going accelerated chemical oxidative stability testing shows no degradation for silica based membranes. These promising results highlight the commercial potential for a new flow battery membrane that is inexpensive, chemically robust and ion selective.

Evaluation of the performance of α-alumina nano-porous ceramic composite membrane for esterification applications in petroleum refinery

The carrier gas permeation performance through α-alumina nano-porous ceramic membrane was investigated in this study. The four carrier gases used for the study were argon (Ar), helium (He), nitrogen (N2) and carbon dioxide (CO2). The experiments was carried out at the gauge pressure drop of 0.10–1.00bar at 80°C. The α-alumina membrane was prepared using the sol-gel dip-coating techniques. The dip-coated membrane exhibited a higher molar flux with He (0.046molm−2s−1) and Ar (0.037molm−2s−1) with a much lower flux for N2 (0.037molm−2s−1) and CO2 (0.035molm−2s−1) at 0.30bar. The membrane recorded a huge decrease of permeance with the four carrier gases in the range of 9.81783E-07molm−2s−1Pa−1 to 1.23237E-06molm−2s−1Pa−1 at 0.50bar. The gas flow rate increased with respect to the pressure drop across the membrane. A plot of the inverse square root of the gases molecular weight showed a linear dependence on the gas permeance. The order of the gas flow rate with respect to the mean pressure was He>Ar>CO2>N2. The membrane was characterised using different methods including liquid nitrogen physisorption (Quantachrome instrument 2013) and scanning electron microscopy (Zeiss EVO LS10 SEM). The liquid nitrogen adsorption isotherm were described using the BET and BJH methods The BET surface area of the 7th dip-coated membrane was found to be higher (5.991m2/g) in contrast to the 8th dipped (3.840m2/g). The BJH pore size distribution of the membrane show a reduction pore size after the modification process. The BET isotherms of the membrane indicated a type IV isotherm with hysteresis on the curve indicating that the membrane can undergo a capillary condensation in the mesoporous region. The SEM/EDAX of support showed a clear surface without evidence of crack while the SEM micrograph of the silica membrane exhibit a bonding on the surface membrane as result of the modification process.

Nanoporous ceramic membranes modified by carbon nanotubes used to separate gaseous mixtures

Studies devoted to the development of ceramic membranes, which are capable of separating gaseous mixtures, first and foremost of H2–CH4, are presented in this paper. The membranes from alumina prepared on the basis of thermochemical activation (TCA) products of gibbsite contain a considerable amount of macropores and possess low selectivity in gas separation. In order to reduce the contribution of macropores to the porous structure of membranes, we have introduced glass additives, which sinter more easily than alumina. Tests of the samples, in which a part of TCA product is replaced by glass, have shown that the factor of separation for gaseous mixtures of H2–CH4 increases to 2.2. In the next part of this work, we synthesize the ceramic membranes, which were modified by carbon nanotubes (CNTs) with an external diameter of 3–5 nm. It is shown that when CNTs are introduced into the composition of a ceramic membrane, the selectivity in the separation of gaseous mixtures of H2–CH4 increases to 2.4.

The Composite of Aluminum Oxide/Pvdf-HFP Membrane for Advanced Li-S Batteries

The potential candidates for post lithium ion batteries, lithium-air (Li-O2) and lithium-sulfur (Li-S) batteries, have been drawing keen attention for large-scale energy storage systems such as automotive and smart-grid applications. Current lithium ion technology is facing to the challenging limitations in high specific capacities and energy densities. Even though the distinctive achievement in insertion-based electrode materials brought the increase of charge-storage capacities, it is still remaining as a huge task of delivering the higher capacity. To overcome these major drawbacks, it is necessary to discern the limitation of electrochemical reactions and devise a promising option. Sulfur is, the most abundant element in the earth’s crust, one of the attracting alternatives for offering the high specific capacity and energy density. The utilization of sulfur as a cathode material undergoes electrochemical conversion reactions with lithium ions in which it accommodates more ions and electrons relative to the lithium-ion batteries. Its theoretical capacity and energy density are as high as 1672 mA h g-1 and 2600 W h kg-1, respectively. There is no doubt the Li-S cell is the possible solution to meet the demand, however, there are some critical prerequisites to commercialization. For example, the conversion reactions accompanying volume expansion, safety issues in use of metallic lithium anode, and polysulfides dissolution by shuttle mechanism have been not yet solved satisfactorily for the past decades. Herein, we introduce the composite of anodic aluminum oxide (AAO) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer as lithium ion transport media in Li-S battery system for prevention of polysulfide shuttle reaction, which leads to capacity fading due to loss of active material from the cathode, and utilization of metallic lithium as anode. With the perspectives, our composite material can act as a separator to avoid electrical short-circuiting between anode and cathode, also, as a solid-state gel polymer electrolyte facilitating lithium ion transportation. Moreover, both AAO and PVdF-HFP have relatively high dielectric constant (ε) (about 9 and 8.4, respectively), which can help effective dissolution of lithium salts and maintain high concentration of charge carriers [1]. The configuration of AAO/PVdF-HFP composite is noteworthy that the poreless PVdF-HFP layer can effectively impede the lithium polysulfides dissolution and travelling to the surface of metallic lithium anode, where insoluble phase of Li2S is formed resulting in low coulombic efficiency (CE) and long-term cyclability [2]. Also, the hexagonal nanopore-arrays of AAO induces the uniform current pathways and high rate of liquid electrolyte uptake with infiltration as reported in the previous study. In terms of the mechanical properties, the composite of gel polymer electrolyte and ceramic separator exhibits excellent mechanical reinforcement to inhibit the short-circuit risk by lithium dendrite formation [3]. In conclusion, the model study of composite material with anodic aluminum oxide (AAO) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer is expected that structurally ideal construction of separator-electrolyte system for Lithium-sulfur batteries (Li-S) can solve the challenging issues of capacity loss by polysulfides blocking via poreless character of PVdF-HFP layer. Furthermore, the composite can bring the enhancement of electrochemical performance, the part of gel polymer electrolyte decreases the interfacial resistance, and high mechanical moduli of nanoporous ceramic membrane leads to stable operation with metallic lithium anode. Thus, the model study of AAO/PVdF-HFP composite provides the possible solution to safety concerns on Li metal anode and an advanced Li-S cell configuration.