Described herein is a graphene and polyvinyl alcohol based multilayer composite membrane that provides selective resistance for solutes to pass through the membrane while providing water permeability. A selectively permeable membrane comprising a crosslinked graphene with a polyvinyl alcohol and an additive that can provide enhanced salt separation from water, methods for making such membranes, and methods of using the membranes for dehydrating or removing solutes from water are also described.

A reverse osmosis membrane treatment system is provided with a first reverse osmosis membrane treatment device wherein water to be treated is passed through a first reverse osmosis membrane to obtain first permeate water and first concentrated water, and at least a second reverse osmosis membrane treatment device, wherein the first permeate water is passed through a second reverse osmosis membrane to obtain second permeate water and second concentrated water. The permeation flux per 1 MPa of effective pressure for the second reverse osmosis membrane is lower than the permeation flux per 1 MPa of effective pressure for the first reverse osmosis membrane, and the permeation flux per 1 MPa of effective pressure for the second reverse osmosis membrane is 0.5 m.sup.3/m.sup.2/d or less.

A monolayer membrane containing gelling polymer particles having at least one of a basic functional group and an acidic functional group, and having a thickness of less than 5 ?m. A composite having a porous carrier and gelling polymer particles having at least any one of a basic functional group and an acidic functional group and filling up the surface pores of the porous carrier. The invention can provide a novel material capable of efficiently separating an acid gas from a mixed gas.

This invention relates generally to a chitosan-graphene oxide membrane and process of making the same. The nanocomposite membrane can filter water and remove contaminants without fouling like other commercially-available polymer-based water filters. The membrane can be used as a flat sheet filter or can be engineered in a spiral filtration module. The membrane is scalable and tunable for many water contaminants including pharmaceuticals, pesticides, herbicides, and other organic chemicals. The membrane uses chitosan, which is low-cost, renewable biopolymer typically considered to be a waste product and the second most abundant biopolymer on Earth, thus making the membrane an environmentally-friendly product choice.

The present disclosure is directed to methods and systems for detecting a substance of interest. The methods and systems include contacting the substance of interest with a doped membrane, the doped membrane comprising at least one semi-permeable medium doped with at least one acid. The systems and methods further include desorbing the doped membrane to release the substance of interest, performing an analysis of the substance of interest, and detecting the substance of interest.

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.

Provided is an interfacial polymerization process for preparation of a thin film composite membrane, which can be used for nanofiltration, forward osmosis, or reverse osmosis, particularly for use with brackish water or seawater. The process includes contacting a porous support membrane with an aqueous phase containing a polyamine to form a coated support membrane, and applying an organic phase containing a polyfunctional acyl halide to the coated support membrane to interfacially polymerize the polyamine and the polyfunctional acyl halide to form a discrimination layer of a thin film composite membrane, where during formation of the membrane, the polyfunctional acyl halide is purified in situ by removal of hydrolyzed acyl halide through addition of a salt rejection-enhancing additive that includes a biguanide compound, dicarbonate compound, pentathiodicarbonate compound, or salt thereof. Also provided are the membranes prepared by the methods and reverse osmosis modules containing the membranes.

Provided is an interfacial polymerization process for preparation of a thin film composite membrane, which can be used for nanofiltration, forward osmosis, or reverse osmosis, particularly for use with brackish water or seawater. The process includes contacting a porous support membrane with an aqueous phase containing a polyamine to form a coated support membrane, and applying an organic phase containing a polyfunctional acyl halide to the coated support membrane to interfacially polymerize the polyamine and the polyfunctional acyl halide to form a discrimination layer of a thin film composite membrane, where during formation of the membrane, the polyfunctional acyl halide is purified in situ by removal of hydrolyzed acyl halide through addition of a salt rejection-enhancing additive that includes a biguanide compound, dicarbonate compound, pentathiodicarbonate compound, or salt thereof. Also provided are the membranes prepared by the methods and reverse osmosis modules containing the membranes.

The present disclosure provides a rigid self-supporting MXene separation membrane and a preparation method and use thereof, belonging to the technical field of membranes. In the present disclosure, a MXene material is mixed with an aluminum salt powder to conduct one-step membrane formation by hot-pressing. The pressure forms the powder into a membrane and imparts rigidity, enabling a self-supporting structure; the heating breaks an ionic bond of an inorganic metal salt to reach a molten ionic state, and free metal cations react with active oxygen-containing functional groups on the surface of the MXene to form new chemical bonds (such as an AlO bond); such a chemical bond has higher energy, achieving a desirable anti-swelling effect to improve the membrane stability. The separation membrane further has excellent conductivity and hydrophilicity.