A preparation method of separation membrane is provided. First, a polyimide composition including a dissolvable polyimide, a crosslinking agent, and a solvent is provided. The dissolvable polyimide is represented by formula 1:

##STR00001##

wherein B is a tetravalent organic group derived from a tetracarboxylic dianhydride containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group, A′ is a divalent organic group derived from a diamine containing aromatic group and carboxylic acid group, and 0.1≦X≦0.9. The crosslinking agent is an aziridine crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a diamine crosslinking agent, or a triamine crosslinking agent. A crosslinking process is performed on the polyimide composition. The polyimide composition which has been subjected to the crosslinking process is coated on a substrate to form a polyimide membrane. A dry phase inversion process is performed on the polyimide membrane.

System, devices, and method for the production of thin film composite hollow fiber membranes on a hollow fiber support structure. The system includes a comb and roller device, or comb and dual roller device, which can be used to define a submerged travel path in a first solution bath for a hollow fiber. The combs and rollers control the amount of time the hollow fiber spends in the first solution. The first solution contains a first monomer, and the hollow fiber is impregnated with the first monomer. The amount of impregnation depends on the time spent in the first solution. Subsequent immersion in a second solution containing a second monomer results in the formation of a thin film composite hollow fiber membrane.

A thin film composite membrane (TFC) includes an active layer on a support. The active layer includes at least 8 barrier layers of star-polymers each having at least three linear polymers attached at a central core. Each of the barrier layers has a thickness between 5 and 50 nm, and the barrier layers have alternating charge.

Reverse osmosis membranes made by interfacial polymerization of a monomer in a nonpolar (e.g. organic) phase together with a monomer in a polar (e.g. aqueous) phase on a porous support membrane. Interfacial polymerization process is disclosed for preparing a highly permeable RO membrane, comprising: contacting on a porous support membrane, a) a first solution containing 1,3-diaminobenzene, and b) a second solution containing trimesoyl chloride, wherein at least one of solutions a) and b) contains nanoparticles when said solutions are first contacted, and recovering a highly permeable RO membrane.

A hand-carry gravity-driven water filter with high throughput and water disinfection performance is formed. Membranes used for this water filter can be fabricated using electrospun method and non-solvent induced phase inversion method. A novel composite membrane structure (interwoven composite structure) was designed for further enhances water permeability and mechanical strength. The composite membrane can be composed of nanofibers with different diameter from the same polymer or different polymers. Membrane porosity and surface pore size can be controlled. Silver nanoparticles can be in-situ loaded on the surface of the membranes. The developed filter is effective for removal of a wide range of contaminants (e.g., pathogens, suspended solids and heavy metals). The purification process can be carried out under the drive of gravity (with an option for mechanically-enhanced filtration) without electricity.

An electrochemical compressor utilizes an anion conducting layer disposed between an anode and a cathode for transporting a working fluid. The working fluid may include carbon dioxide that is dissolved in water and is partially converted to carbonic acid that is equilibrium with bicarbonate anion. An electrical potential across the anode and cathode creates a pH gradient that drives the bicarbonate anion across the anion conducting layer to the cathode, wherein it is reformed into carbon dioxide. Therefore, carbon dioxide is pumped across the anion conducting layer. The compressor may be part of a refrigeration system that pumps the working fluid in a closed loop through a condenser and an evaporator.

Highly energy efficient electrodialysis membranes having low operating costs and a novel process for their manufacture are described herein. The membranes are useful in the desalination of water and purification of waste water. They are effective in desalination of seawater due to their low electrical resistance and high permselectivity. These membranes are made by a novel process which results in membranes significantly thinner than prior art commercial electrodialysis membranes. The membranes are produced by polymerizing one or more monofunctional ionogenic monomers with at least one multifunctional monomer in the pores of a porous substrate.

A porous polymer membrane useful in gas separation, the porous polymer membrane comprising a polymeric structure having crosslinked aromatic groups and a hierarchical porosity in which micropores having a pore size less than 2 nm are present at least in an outer layer of the porous polymer membrane, and macropores having a pore size of over 50 nm are present at least in an inner layer of the porous polymer membrane. Also described are methods for producing the porous polymer membrane in which a non-porous polymer membrane containing aromatic rings is subjected to a Friedel-Crafts crosslinking reaction in which a crosslinking molecule crosslinks the aromatic rings in the presence of a Friedel-Crafts catalyst and organic solvent under sufficiently elevated temperature, as well as methods for using the porous polymer membranes for gas or liquid separation, filtration, or purification.

Provided herein are methods of making asymmetric membranes comprising a first layer and a second layer. The methods include preparing a polymeric solution comprising one or more polymers, casting the polymeric solution to form a polymeric film, contacting the polymeric film with a solvent comprising a crosslinker under conditions to form a first layer on the top of the film, wherein the first layer is dense and solvent resistant, and contacting the polymeric film having the dense, solvent-resistant first layer with a non-solvent solution under conditions that form a porous second layer on the bottom of the film.

Disclosed are copolymers which are useful in hydrophilically modifying porous fluoropolymer supports. An example of the copolymers is: ##STR00001##
Also disclosed are a method of preparing such copolymers, a method of modifying porous fluoropolymer surfaces, and hydrophilic fluoropolymer porous membranes prepared therefrom. Also disclosed is a method of filtering fluids by the use of the hydrophilic fluoropolymer porous membranes.