Development Of Inorganic Membranes Research Articles

Book Review Advanced Materials for Wastewater Treatment and Desalination: Fundamentals to Applications

Book Review Advanced Materials for Wastewater Treatment and Desalination: Fundamentals to Applications

Interfacial assembling of flexible silica membranes with high chlorine resistance for dye separation

Inorganic membranes have gained extensive attention due to their more uniform pore size, higher flux, and better chemical stability over traditional polymeric membranes. However, the development of inorganic membranes still faces substantial obstacles in the form of a difficult preparation procedure and the high cost of a large-scale synthesis. Herein, a facile interfacial assembly strategy is designed to prepare flexible silica membranes by the close and strong packing of ultra-small nanoparticles via crosslinking with trimesoyl chloride. Profiting from the extremely small size and tight packing of silica nanoparticles, the permeance of flexible silica membrane with a uniform pore size of 3.4 nm exceeds 210 L m−2 h−1 MPa−1, which is nearly 11 times higher than the polyamide membrane simultaneously ensuring the rejection effect. Meanwhile, the flexible silica membrane has no performance deterioration after exposure to 50000 ppm h of chlorine (NaOCl), indicating its excellent chlorine resistance. The facile interfacial assembly strategy applied for the synthesis of the membrane is highly reproducible and scalable (high-performance silica membrane with 100 cm2 has been obtained), which has overall flexibility after the curvature of 100 m−1, paving the way for the development of future applications.

Permeation Properties of Ions through Inorganic Silica-Based Membranes.

The development of inorganic membranes has mainly found applicability in liquid separation technologies. However, only a few reports cite the permeation and separation of liquids through inorganic nanofiltration membranes compared with the more popular microfiltration membranes. Herein, we prepared silica membranes using 3,3,3-trifluoropropyltrimethoxysilane (TFPrTMOS) to investigate its liquid permeance performance using four different ion solutions (i.e., NaCl, Na2SO4, MgCl2, and MgSO4). The TFPrTMOS-derived membranes were deposited above a temperature of 175 °C, where the deposition behavior of TFPrTMOS was dependent on the organic functional groups decomposition temperature. The highest membrane rejection was from NaCl at 91.0% when deposited at 200 °C. For anions, the SO42− rejections were the greatest. It was also possible to separate monovalent and divalent anions, as the negatively charged groups on the membrane surfaces retained pore sizes >1.48 nm. Ions were also easily separated by molecular sieving below a pore size of 0.50 nm. For the TFPrTMOS-derived membrane deposited at 175 °C, glucose showed 67% rejection, which was higher than that achieved through the propyltrimethoxysilane membrane. We infer that charge exclusion might be due to the dissociation of hydroxyl groups resulting from decomposition of organic groups. Pore size and organic functional group decomposition were found to be important for ion permeation.

High performance membrane materials for gas separation

The use of membranes in various gas separations has increased significantly in recent times. This review presents some of the recent noteworthy advances in the field of membranes materials for these applications. A description of the most promising groups of high free volume polymers, including polyimides, thermally rearranged (TR) polymers, substituted polyacetylenes, perfluoropolymers, and polymers with intrinsic microporosity (PIM) is provided. High performance, rubbery, polyethers and polyether based copolymers are shown as another important class of polymer membrane materials. The development of inorganic membranes, which are not bound to the trade-off limitations between permeability and selectivity exhibited by polymers is also presented. The attention is focused on zeolitic materials, metal organic frameworks (MOF), and carbon molecular sieves (CMS). The field of mixed matrix membranes composed of inorganic particles embedded in a polymer matrix is also briefly outlined.

Innovative ceramic hollow fiber membranes for recycling/reuse of oilfield produced water

The focus of this study was on the development and application of ceramic hollow fiber membrane (CHFM) technology for the treatment of oilfield produced water (PW) prior to disposal/discharge into the environment. PW refers to any fossil water that is brought to the surface along with crude oil or natural gas. It is a complex mixture of dispersed oil, dissolved organic compounds, suspended solids, production chemicals, heavy metals, and natural radioactive minerals. PW is difficult to handle/treat and represents the largest volume of waste associated with the oil and gas industry. It can have different potential impacts on offshore or onshore environments depending on where it is discharged. Therefore, the development of effective treatment technologies for PW is essential from both ecological and economic standpoints. The first stage of any treatment process for PW consists of a significant reduction in the level of dispersed hydrocarbons and suspended solids. In a second and often in a third stage, the oil and total carbon (TC) content is reduced by hydrocyclones and by micro- and ultrafiltration using membrane technologies. Due to legal requirements, final oil contents below 10 ppm are required in some regions before PW disposal to the environment. CHFMs represent a new generation in the development of inorganic membranes by offering the advantages of one membrane consisting of both inorganic material and hollow fiber geometry. In this study, the effect of cross-flow velocity on the CHFM performance at a low trans-membrane pressure of 0.5 bar, as well as the permeate quantity and quality, was investigated in terms of fouling behavior and efficiency of oil and TC removal. In the filtration system presented here, using ceramic hollow fiber ultrafiltration (UF) membranes with a d90 pore diameter of 40 nm, the removal of oil and TC from samples of tank dewatering produced water and oily model systems, was successfully demonstrated with a remarkable decontamination efficiency of >99.5% (oil) and 61–94% (TC), respectively.

エネルギー効率利用に向けたCVD法による無機分離膜の開発

エネルギー効率利用に向けたCVD法による無機分離膜の開発

Microporous silica and doped silica membrane for alcohol dehydration by pervaporation

The aim of this work is the development of inorganic membranes that will enable broad application of pervaporation/vapour permeation technology in the chemical industry. This can be achieved by improvement of the existing microporous membranes and the development of new types with enhanced thermochemical stability and separation characteristics. The materials in the system, SiO 2Al 2O 3TiO 2ZrO 2MgO, were investigated with respect to their chemical stability and pervaporation performance in alcohol dehydration processes. It was found that, depending on the nature and amount of dopant, composite membranes with improved pervaporation characteristics and chemical stability were obtained.

CVD techniques for gas separation membranes synthesis - characterization - applications

Membranes used in the separation of gas phase have found a number of important applications. In the past few years, the development of inorganic membranes, which have numerous advantages (thermal and mechanical stabilities, steam cleaning ability...) paved the way for high temperature applications. Inorganic membranes are widely used in gas separation processes such as reversible dehydrogenation reaction, O-2/N-2 separation, CO2 and volatil organic compounds recovery... Usually, inorganic membranes (SiO2, Al2O3, TiO2,, ZrO2, Pd...) are deposited on porous substrates in the sol-gel way. CVD techniques can be used as an alternative process for the deposition of very thin films in a wide range of temperature. The membranes deposited belong to the oxide, nitride, carbide and mixted metal compounds. We will present the different CVD techniques used in membranes synthesis : conventional CVD and OMCVD, counterdiffusion CVD, plasma assisted CVD. From a porous substrate, the CVD techniques lead to the pore diameter reduction or film deposition on the top of the membrane and plugs penetrating the pore entrance. Some examples of.-as separation membranes coated by CVD will be developed.

Microporous Inorganic Membranes for Gas Separation

Microporous inorganic membranes are potentially useful in gas separation in emerging areas such as catalytic reactors, gasification of coal, molten-carbonate and solid-electrolyte fuel cells, and water decomposition by thermochemical reactions. If the feed or product gases can be separated at elevated temperatures specific to each process, the energy required for purification could be greatly reduced. Advances in the development of inorganic membranes have been quite rapid in recent years. For example, in 1991 the reported CO2/N2 selectivity at ambient temperature was less than 10, but by 1997 it had improved to approximately 100.The permeation rate and permselectivity of porous inorganic membranes are dependent on the microstructures of membrane/support composites such as pore size and distribution, porosity, tortuosity, and the affinity between permeating species and pore walls. Figure 1 shows the relationship between molecular weight and kinetic diameter (calculated from minimum equilibrium cross-sectional diameter) for a selected series of molecules. Hydrogen and helium are smaller and lighter than the others. Structural isomers such as n-C4H10 and i-C4H10 have the same mass but quite different sizes. Therefore, the control of micropores is of critical importance in these cases. However, the molecular masses and sizes of CO2 and N2 are not greatly different; thus the difference in affinity is important for separation of these molecules.In order to achieve effective separation of small-molecule gases, the membrane pores should be smaller than 2 nm. In the case of mesopores or macropores, gases permeate with low selectivities through these pores. In this article, preparation processes and permeation properties of porous inorganic membranes are reviewed, and permeation mechanisms are discussed.