A desalination battery cell includes a first compartment separated by an anion exchange membrane from a second compartment, each of the first and second compartments containing a saline water solution having a concentration of dissolved salts c.sub.1 and first and second intercalation host electrodes, respectively, in fluid communication with the solution, a voltage source supplying electric current to the first and second intercalation host electrodes to release cations into the solution, and a controller programmed to adjust an amount of the electric current being supplied to change direction of anions in the solution passing through the anion exchange membrane between the compartments such that the first and second compartments alternately collect and disperse salt from the solution and release desalinated water solution having a concentration c.sub.2 of dissolved salts and a brine solution having a concentration c.sub.3 of dissolved salts such that c.sub.3>C.sub.1>C.sub.2.

Systems and methods for electrochemical separation are provided. An electrochemical separation device may include at least one cell pair wound around an electrode to from a bundle having a racetrack configuration.

A target analyte is extracted out of a sample fluid in a sample fluid passage by diffusing the target analyte through a supported liquid membrane to a product fluid passage. Extraction of the target analyte is accelerated by applying an electric field across and perpendicular to the supported liquid membrane with electrodes. Passage of selected ions across an exchange membrane extending between one of the electrodes and the supported liquid membrane is inhibited.

A membrane structure is provided. The membrane structure may include: a membrane; at least one hole extending into the membrane configured to receive a fluid. The membrane may include a plurality of electrodes arranged to provide one or more electric fields to control a movement of the fluid within the at least one hole.

Surface conduction in porous media can drastically alter the stability and morphology of electrodeposition at high rates, above the diffusion-limited current. Above the limiting current, surface conduction inhibits growth in the positive membrane and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization shock in the negative membrane. The discovery of uniform growth contradicts quasi-steady leaky membrane models, which are in the same universality class as unstable Laplacian growth, and indicates the importance of transient electro-diffusion or electro-osmotic dispersion. Shock electrodeposition could be exploited for high-rate recharging of metal batteries or manufacturing of metal matrix composite coatings.

A method and apparatus for reduction of biofouling on reverse osmosis membranes is provided. One embodiment provides a charged filter surrounding a cathode that is, in turn, surrounded by an anode. A plurality of these charged filters may be included in a larger filtration system that may be included in a typical reverse osmosis system.

Disclosed is an energy-saving system and method for direct air capture with precise ion control. The system includes an air conveying device, an air distribution device and a CO.sub.2 adsorption device with a moisture swing adsorbent with high CO.sub.2 adsorption capacity, where the air conveying device, the air distribution device and the CO.sub.2 adsorption device are connected in sequence, and the CO.sub.2 adsorption device is provided with a spray desorption device; a valence-state ion sieving device; a pH swing regeneration device; and a CO.sub.2 regeneration device. In accordance with the energy-saving system provided by the present disclosure, ultra-low concentration of CO.sub.2 in the air can be enriched to the concentration of 95% step by step for industrial application or biological application at room temperature and pressure by consuming the electricity which cannot be connected to a power grid.

Processes, systems, and techniques for multivalent ion desalination of a feed water use an apparatus that has a cathode, an anode, and an electrodialysis cell located between the cathode and anode. The cell has a product chamber through which the feed water flows, a multivalent cation concentrating chamber on a cathodic side of the product chamber through which the concentrated multivalent cation solution flows, and a multivalent anion concentrating chamber on an anodic side of the product chamber through which the concentrated multivalent anion solution flows. The product chamber and the multivalent cation concentrating chamber are each bounded by and share a cation exchange membrane, and the product chamber and the multivalent anion concentrating chamber are each bounded by and share an anion exchange membrane. A monovalent ion species is added to at least one of the concentrated multivalent cation solution and the concentrated multivalent anion solution.

Methods for making multiple walled nested coaxial nanostructures and devices incorporating the coaxial nanostructures are disclosed. The coaxial nanostructures include an inner nanostructure, a first outer nanotube disposed around the inner nanostructure, and a first annular channel between the inner nanostructure and the first outer nanotube. The coaxial nanostructures have extremely high aspect ratios, ranging from about 5 to about 1,200, or about 300 to about 1200.

A method for assessing a state of fouling of a reverse osmosis system is provided. The method comprises deriving a plurality of impedance values from a low frequency region of an electrical impedance spectrum of a reverse osmosis membrane comprised in the reverse osmosis system, and determining a state of fouling of the reverse osmosis system based on 10 the plurality of derived impedance values. Use of the method for in-situ monitoring of fouling on a reverse osmosis membrane, and an apparatus for assessing a state of fouling of a reverse osmosis system are also provided.