A two-layer membrane including a polymer layer and a support layer, the polymer layer being disposed on a surface of the support layer. The polymer layer, having a pore size of at most 50 nm and a thickness of 5 nm to 10 μm, is formed of an amphiphilic copolymer that contains both charged groups and hydrophobic groups. The support layer has a pore size of 3 nm to 10 μm, which is larger than the pore size of the polymer layer. Also disclosed is a process of filtering a liquid using the two-layer membrane described above.

The present invention relates to a porous sheet product, to a filter element comprising the porous sheet product, to a method for producing the porous sheet product, to a method for producing the filter element, and to the use of the sheet product and of the filter element.

A conventional media filter such as a gravity sand filter is converted into a membrane filter. The media is removed and replaced by immersed membrane modules. Transmembrane pressure is created by a static head pressure differential, without a suction pump, thereby creating a membrane gravity filter (MGF). Preferred operating parameters include transmembrane pressure of 5-20 kPa, 1-3 backwashes per day, and a flux of 10-20 L/m.sup.2/h. The membranes are dosed with chlorine or another oxidant, preferably at 700 minutes*mg/L as Cl.sub.2 equivalent per week or less. The small oxidant does is believed to provide a porous biofilm or fouling layer without substantially removing the layer. The media filter may be modified so that backwash wastewater is removed from near the bottom of the tank rather than through backwash troughs above the membrane modules. Membrane integrity testing may be done while the tank is emptied after a backwash.

In at least one embodiment, a microporous membrane having a moderate to high water vapor permeability and high liquid water penetration resistance is disclosed. The microporous membrane may be used in building applications, including as or as part of a building wrap, a rain screen, a roofing underlayment, a flashing, a sound proofing material, or an insulation material. The microporous membrane may include at least one thermoplastic polymer, at least one filler, and at least one processing oil. The microporous membrane may be flat or may have ribs. The microporous membrane may include at least one scrim component. A method for forming the microporous membrane is also disclosed.

[Problem to be Solved]

Provided is a polyvinylidene fluoride resin-made porous membrane having excellent hydrophilicity, permeability, and fouling resistance and having suppressed elution of vinyl ether copolymer by using a small amount of vinyl ether copolymer.

[Means to Solve the Problem]

The porous membrane according to the invention comprises a polyvinylidene fluoride resin as a matrix material and a vinyl ether copolymer, wherein the vinyl ether copolymer is a copolymer of an oxyethylene group-containing vinyl ether monomer and a hydrocarbon group-containing vinyl ether monomer.

A fluid control device includes a support structure configured to be deployed to a selected location in a borehole, and a filtration medium disposed at the support structure and configured to filter a fluid, the filtration medium configured to be compacted from an initial shape to a compacted shape prior to deployment in the borehole. The filtration medium includes a first polymeric material configured to withstand a temperature at the selected location, the first polymeric material forming a porous structure including a plurality of fluid passages, and a second polymeric material including a shape memory polymer disposed within the fluid passages, the shape memory polymer configured to expand in the plurality of fluid passages and cause the filtration medium to expand in the borehole.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

A preparation method of a gradient long-effective catalytic membrane with high-strength and anti-deposition property is provided and includes: adding a nanometal oxide catalyst into an N, N-dimethylformamide solution of polyacrylonitrile or polystyrene, uniformly mixing, performing electrostatic spinning, keeping a receiver at −190° C. to −200° C. in the electrostatic spinning process, and performing freeze drying on a precursor membrane obtained after the electrostatic spinning is finished, so as to obtain the gradient long-effective catalytic membrane. According to the method, the gradient long-effective catalytic membrane with high-strength and anti-deposition property is obtained through a one-step method which adopts an ultralow-temperature-electrostatic spinning technology and combines with nanometal, the contradictory relation between the catalytic efficiency and the membrane stability in a traditional catalytic membrane is solved, the catalytic performance of the membrane is fully played, the organic polluted wastewater can be efficiently catalytically degraded, and the service life of the catalytic membrane is prolonged.

A filtration membrane coating comprising a hydrophilic polymer, a surfactant, and one or more charged compounds, each containing one or more sulfonate functionalities and one or more linkable functionalities selected from the group consisting of amine, monochlorotriazine, and dichlorotriazine. The hydrophilic polymer and surfactant form a thin primer layer which is also superhydrophilic. The primer layer improves flux, and enables improved adhesion of the one or more charged compounds, which form a charged dye layer on top of the primer layer when enhances rejection of charged divalent ions. The coating can be applied while the membrane is packaged in its final form, such as in a spiral wound or other configuration.

Multicomponent copolymers including two or more types of repeat units is presented. In one example, the multicomponent copolymer includes at least one repeat unit AC having a structure (I), at least one repeat unit DC having a structure (II), and at least one repeat unit BC having a structure (III) or (V). The multicomponent copolymer may be cross-linked via a cross-linking agent. A polymer blend including the multicomponent copolymer or a cross-linked copolymer and a second polymer is also provided. The multicomponent copolymer may be a random or a block copolymer. The structural units of the multicomponent copolymers provide improved, tunable properties, such as improved biocompatibility and hydrophilicity, protein fouling, and mechanical properties, to the copolymers and/or the membranes fabricated from the copolymers.