▎ 摘　　要

NOVELTY - Deionizing water carrying unwanted ions involves: providing sheet of graphene (212) with several apertures (312) to allow passage of water molecules and to disallow passage of selected one of unwanted ions to form perforated graphene; pressurizing water carrying unwanted ions; applying pressurized water to first surface (212u) of perforated graphene so that water molecules flow to second side (212d) of perforated graphene sheet in preference to ions; and collecting water molecules (202) from second side of graphene sheet. USE - For deionizing water carrying unwanted ions (claimed), such as for converting seawater into clean drinking water. ADVANTAGE - In the apparatus or arrangement for deionizing water, pressure of ion-laden water applied through path to perforated membrane can be provided by gravity from water tank. Thus, unlike reverse osmosis (RO) membrane, perforated graphene sheet forming perforated membrane is hydrophobic, and water passing through pierced apertures is not impeded by attractive forces attributable to wetting. Also, length of flow path through apertures in graphene sheet is equal to thickness of sheet, which is about 2 nm. This length is much less than lengths of random paths extending through RO membrane. Consequently, very little pressure is required to provide fluid flow, or conversely, flow at given pressure is much greater in perforated graphene sheet. This, in turn, translates to low energy requirement for ion separation. The pressure required in RO membrane to force water through membrane against osmotic pressure includes frictional component which results in heating of membrane. Consequently, some of the pressure which must be applied to RO membrane does not go toward overcoming osmotic pressure, but instead goes into heat. Simulated results show that perforated graphene sheet reduces required pressure by at least a factor of 5. Thus, where RO membrane might require 40 pounds per square inch (PSI) of pressure on upstream side to effect particular flow of deionized water at particular ion concentration, the perforated graphene sheet for same flow rate may require less than or equal to 8 PSI. DETAILED DESCRIPTION - Method for deionizing water carrying unwanted ions involves: providing sheet of graphene (212) with several apertures (312) selected to allow passage of water molecules and to disallow passage of selected one of unwanted ions to generate perforated graphene; pressurizing water carrying unwanted ions to generate pressurized water; applying pressurized water to first surface (212u) of perforated graphene so that water molecules flow to second side (212d) of perforated graphene sheet in preference to ions; and collecting water molecules (202) from second side of graphene sheet. When unwanted ions are chlorine, apertures for disallowance of chlorine ions are nominally 9 nm. When unwanted ions are sodium, apertures for disallowance of sodium ions are nominally 6 nanometers. The apertures are nominally spaced apart by 15 nm. The method further involves reinforcing sheet of perforated grapheme by backing (220). The step of backing includes backing with grid. The step of providing sheet of graphene with several apertures selected to allow passage of water molecules and to disallow passage of selected one of unwanted ions involves applying oxidizer to at least portion of sheet of graphene to generate apertures; and further involves before applying oxidizer masking those portions of graphene at which apertures are not desired. INDEPENDENT CLAIMS are included for the following: (1) water deionizer comprising: graphene sheet perforated with apertures dimensioned to allow flow of water molecules and to disallow flow of ions of particular type; source of water laden with ions of particular type; and path for flow of water laden with ions of particular type through graphene sheet perforated with apertures; and (2) separator comprising: first graphene sheet perforated with apertures dimensioned to allow flow of water molecules and to disallow flow of ions of first type; second graphene sheet perforated with apertures dimensioned to allow flow of water molecules and to disallow flow of ions of second type, where ions of second type are smaller than ions of first type; source of water laden with ions of first and second types; path for applying flow of water laden with ions of first and second types to first graphene sheet, so that ions of first type accumulate on upstream side of first graphene sheet, and water laden with ions of second type flows through first graphene sheet to downstream side of first graphene sheet; path for applying flow of water laden with ions of second type to upstream side of second graphene sheet, so that ions of second type accumulate on upstream side of second graphene sheet and water free of ions of first and second types flows through second graphene sheet; and a collection arrangement coupled to receive water free of ions of first and second types. DESCRIPTION OF DRAWING(S) - The figure shows perforated graphene sheet for deionizing water carrying unwanted ions showing shape of apertures. Unfiltered water (201) Deionized water (202) Perforated graphene sheet (212) Second side of perforated graphene sheet (212d) First surface of perforated graphene (212u) Tank containing gravity fed salt water (216) Backing structure (220) Apertures in graphene sheet (312)