The present disclosure relates to a polyether block polyamide/polydimethylsiloxane (PDMS) composite membrane for gas separation, and a preparation method and use thereof, and belongs to the technical field of membrane separation. In the present disclosure, an amphoteric copolymer PDMS-polyethylene oxide (PEO) (PDMS-b-PEO) is introduced into an intermediate layer to adjust the interfacial binding performance, thereby promoting preparation of an ultra-thin polyether block polyamide composite membrane. Studies have shown that the surface enrichment of PEO segments not only inhibits a dense SiO.sub.x layer formed due to a plasma treatment of a PDMS intermediate layer, but also provides additional hydrophilic sites and interfacial compatibility for the subsequent selective layer. The use of PDMS-b-PEO in an intermediate layer allows the successful preparation of a selective layer with a thickness of about 50 nm.

Nitrogen is removed from biogas using a three-stage separation system based on gas separation membranes. The first stage separates a biomethane feed stream into a first permeate gas stream and a first retentate gas stream. The second stage separates the first permeate stream into a biomethane product gas and a first low quality biomethane gas stream. The third stage separates the first retentate into a second low quality biomethane gas stream and a waste gas. A biogas feed stream is pretreated to remove amounts of water, VOCs, and CO.sub.2 to yield a methane-enriched biogas stream. The methane-enriched biogas stream is compressed together with the first and second low quality biomethane gas streams to form the biomethane feed stream.

An aspect of the present invention relates to a separation membrane for selectively separating a component (A) from a fluid containing the component (A) and a component (B), wherein the separation membrane has a first surface and a second surface opposite to the first surface, an affinity of the first surface side of the separation membrane for the component (A) is higher than an affinity of the first surface side of the separation membrane for the component (B), and an affinity of the second surface side of the separation membrane for the component (A) is higher than the affinity of the first surface side of the separation membrane for the component (A).

Disclosed herein is a process for separation and purification of a fermentation gas product from a fermenter off-gas containing a fermentation product, volatile impurities, bio-product impurities and water, based on a membrane system. In one preferred embodiment of the present invention, the process of separating and purifying a fermentation product from a fermenter off-gas, containing the fermentation product, volatile impurities, bio-byproduct impurities and water, comprises the steps of: (a) compressing the fermenter off-gas and feeding it into a membrane module, and (b) selectively permeating the volatile impurities, bio-byproduct impurities and water through the membrane, resulting in a product rich retentate stream. The fermentation gas product is separated from the fermenter off-gas in a single membrane stage to produce a purified retentate stream. In accordance with this embodiment of the invention, the fermenter off-gas (2), comprising the fermentation gas product, volatile impurities, bio-byproduct impurities and water, passes through a blower (201) that transports it to a gas holder (202), in order to smooth the process fluctuations. Stream (11) exits the gas holder (202) and is compressed in a multi-stage compressor (203), from which bio-byproduct and water are removed through stream (4). The compressed stream (12) enters the membrane module (204), which permeates the volatile impurities, disposing them in stream (13). The process may be still conducted in a 2-stage membrane system in accordance with the present invention.

A membrane process is provided for separating light olefins from light paraffins to produce a polymer grade light olefin product stream that is about 99.5 mol % ethylene or propylene. The process involves multiple stages to achieve the high purity product and provides for processing hydrocarbon streams that have differing concentrations of light olefins.

The present specification provides a composition comprising a material of Chemical Formula 1:

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having a molecular weight of 500,000 to 700,000 where R1 and R2 are the same as or different from each other, and each independently is hydrogen, deuterium, or an alkyl group, and n is from 10,000 to 20,000, for forming a reverse osmosis membrane protective layer, a method for preparing a reverse osmosis membrane using the same, a reverse osmosis membrane and a water-treatment module.

A porous membrane has a thickness of 150 m or greater. The pore diameters of a first surface are smaller than the pore diameters of a second surface. The average value of the pore diameters of the first surface is 60 nm or less, and the coefficient of variation of the pore diameters is 10% or greater and 50% or less.

An amphiphilic block copolymer comprises a poly(phenylene ether) block or a poly(phenylene ether) copolymer block and a hydrophilic block or graft. A method of making the amphiphilic block copolymer comprises polymerization of a hydrophilic ethylenically unsaturated monomer in the presence of poly(phenylene ether) or a poly(phenylene ether) copolymer to make the amphiphilic block copolymer. A porous asymmetric membrane comprises a poly(phenylene ether) or poly(phenylene ether) copolymer, and the amphiphilic block copolymer comprising a poly(phenylene ether) block or a poly(phenylene ether) copolymer block, and a hydrophilic block or graft. The porous asymmetric membrane is made by phase-inversion of a dope solution of the poly(phenylene ether) or poly(phenylene ether) copolymer and the amphiphilic block copolymer in a coagulation bath.

Multilayer single-bore hollow fibre membranes M or multilayer multi-bore hollow fibre membranes M for ultrafiltration applications are disclosed, comprising at least one hollow fibre membrane substrate S comprising a polymer bulk material P1 and at least one functional layer F disposed on at least the inner surface of the hollow fibre membrane substrate S, wherein the functional layer F comprises at least one polymer P2. The hollow fibre membranes may be used in ultrafiltration methods and filtration modules, in particular for the treatment of waste water.

A membrane process is provided for separating light olefins from light paraffins to produce a polymer grade light olefin product stream that is about 99.5 mol % ethylene or propylene. The process involves multiple stages to achieve the high purity product and provides for processing hydrocarbon streams that have differing concentrations of light olefins.