In a method for forming nanopores, two opposing surfaces of a membrane are exposed to an electrically conducting liquid environment. A nanopore nucleation voltage pulse, having a first nucleation pulse amplitude and duration, is applied between the two membrane surfaces, through the liquid environment. After applying the nanopore nucleation voltage pulse, the electrical conductance of the membrane is measured and compared to a first prespecified electrical conductance. Then at least one additional nanopore nucleation voltage pulse is applied between the two membrane surfaces, through the liquid environment, if the measured electrical conductance is no greater than the first prespecified electrical conductance.

The invention provides a membrane comprising tubes extending through a polymer, wherein substantially all of the tubes are parallel with each other. Also provided is a method for producing a membrane, the method comprising: placing tubes on a substrate, subjecting the tubes to a magnetic field for a time and at a magnetic field strength to cause the tubes to align parallel with each other while simultaneously causing depending ends of the tubes to embed within the substrate; applying polymer to the tubes and substrate in an amount to affix the tubes relative to each other and relative to the substrate, and applying an etchant that cleaves a specific type of the bonds within the polymer to unblock the upstream ends of the nanotubes.

A substrate surface may be modified with a polymer coating to render the surface suitable for plasma functionalization. The polymer coating is deposited onto the surface at ambient temperature to a thickness of less than 0.1 m. The polymer coating includes poly(p-xylylene) or a derivative thereof, and is capable of penetrating into pores of a porous substrate while no substantially altering the porosity of the substrate. The coated substrate is selected from a material lacking a primary or secondary aliphatic hydrogen atom.

A method of preparing a graphene-based membrane is provided. The method may include providing a stacked arrangement of layers of a graphene-based material, wherein the layers of the graphene-based material define one or more nanochannels between neighboring layers, and varying an electrical charge on a surface of the layers of the graphene-based material defining the one or more nanochannels to control size selectivity and/or ionic selectivity of the graphene-based membrane. A graphene-based membrane and a method of separating ions from a fluid stream are also provided.

In a method for forming nanopores, two opposing surfaces of a membrane are exposed to an electrically conducting liquid environment. A nanopore nucleation voltage pulse, having a first nucleation pulse amplitude and duration, is applied between the two membrane surfaces, through the liquid environment. After applying the nanopore nucleation voltage pulse, the electrical conductance of the membrane is measured and compared to a first prespecified electrical conductance. Then at least one additional nanopore nucleation voltage pulse is applied between the two membrane surfaces, through the liquid environment, if the measured electrical conductance is no greater than the first prespecified electrical conductance. At least one nanopore diameter tuning voltage pulse, having a tuning pulse voltage amplitude and duration, is applied between the two membrane surfaces, through the liquid environment, if the measured electrical conductance is greater than the first prespecified electrical conductance and no greater than a second prespecified electrical conductance.

The disclosure provides a method for producing a gas separation article, said gas separation article comprising: a gas separation membrane, optionally a support, and optionally an additional support. The disclosure also provides a gas separation membrane obtainable by the aforementioned method as well as use thereof for separation of gases in a gas mixture.

In one aspect, the present invention relates to a membrane material having a first surface, an opposing second surface and a thickness between the first and second surfaces; the membrane material comprising a mineral comprising a metal; and at least one channel between the first surface and the second surface, wherein the channel has a diameter of less than 1 mm.

In one aspect, the present invention relates to a system comprising the membrane material. In one aspect, the present invention relates to a method of purifying a fluid, using said systems and membrane materials.

A water treatment system for removing contaminant from a feed solution is provided. The system includes a hollow fiber membrane chemical reactor (HF-MCR) and a magnetic field generator; or a magnetic confinement-enabled column reactor (MCCR) comprising one or more column filters and a magnetic field generator. The magnetic field generator is arranged to produce a magnetic field for realizing a magnetically confined zone that results in a formation of a plurality of microwires comprising the zerovalent iron (ZVI) nanoparticles or a plurality of ZVI wires comprising ZVI microparticles. The plurality of microwires can be a magnetic catalyst to enable catalytic degradation and chemical immobilization of the contaminant. The plurality of ZVI wires can reduce aqueous As (As.sub.aq) concentration in the feed solution after the feed solution is pumped through the one or more column filters.

High-quality membranes of complex oxide and complex nitrides are provided. Also provided are method of making the membranes by releasing films of the complex oxides and nitrides from an epitaxial heterostructure using metal islands on the surface of the films as strain-absorbing supports. The methods facilitate the release of flat, large-area membranes characterized by the absence of, or a very low density of, cracks and/or wrinkles. The released membranes are free of the surface organic residues that are present on membranes released with the aid of a polymer support.