WO2023044641A1

WO2023044641A1 - A vapor permeation device and methods of the same

Info

Publication number: WO2023044641A1
Application number: PCT/CN2021/119779
Authority: WO
Inventors: Kunzhou LI; Byeongho LEE
Original assignee: Shanghai Tetrels Material Technology Co., Ltd.
Priority date: 2021-09-23
Filing date: 2021-09-23
Publication date: 2023-03-30
Also published as: CN118076426A

Abstract

A vapor permeation process to separate a binary vapor using a graphene oxide membrane is disclosed.

Description

A VAPOR PERMEATION DEVICE AND METHODS OF THE SAME

BACKGROUND

Dehydration and purification of organic solvents have become increasingly important industrial processes. The importance of these processes can be compared against the technical limitations of distillation processes, which are widely implemented. In particular, mixtures of two or more liquids that have a same boiling point, known as an azeotrope or a constant boiling point mixture, have proportions that cannot be altered or changed by simple distillation.

As an alternative to simple distillation for the separation process, membrane separation, referred to as pervaporation, or pervaporative separation, when the feed is a liquid mixture and referred to as vapor permeation when the feed is a vapor mixture, has been explored. Pervaporation and vapor permeation are both membrane-based processes for the selective separation of mixtures of liquids or vapor by partial vaporization through a non-porous or porous membrane that acts as a selective barrier between feed and permeate. It can be effective for diluting solutions containing trace or minor amounts of the component to be removed.

The membrane, itself, is considered a key component in both pervaporation and vapor permeation. Polymeric membranes such as polyvinyl alcohol (PVA) and polyimide, among others, can be used as membranes for alcohol and solvent dehydration, however, there are intrinsic disadvantages for polymeric membranes such as chemical and/or hydrothermal instability. Inorganic membranes using materials such as zeolite A have been developed. However, these membranes are disadvantaged by high manufacturing cost, complicated large-scale preparation, and/or the high cost involved in their processing. Despite considerable progress, polymeric and inorganic membranes continue to display inferior properties as they relate to permeability and selectivity. Therefore, there is a need for novel separation membranes as disclosed herein, which have improved properties and applicability to myriad mixtures.

BRIEF SUMMARY

The present disclosure relates to a vapor permeation device and methods of the same.

In one aspect, the present disclosure relates to a vapor permeation device, comprising a graphene oxide membrane, wherein the graphene oxide membrane is configured to separate a permeation stream comprising water from a feed vapor stream comprising water and an organic solvent. In some cases, the graphene oxide membrane has a separation factor of about 100 to about 4,000. In some cases, the graphene oxide membrane has a separation factor of at least about 100. In some cases, the graphene oxide membrane has a separation factor of at most about 4,000. In some cases, the graphene oxide membrane has a separation factor of about 100 to about 200, about 100 to about 500, about 100 to about 1,000, about 100 to about 2,000, about 100 to about 3,000, about 100 to about 4,000, about 200 to about 500, about 200 to about 1,000, about 200 to about 2,000, about 200 to about 3,000, about 200 to about 4,000, about 500 to about 1,000, about 500 to about 2,000, about 500 to about 3,000, about 500 to about 4,000, about 1,000 to about 2,000, about 1,000 to about 3,000, about 1,000 to about 4,000, about 2,000 to about 3,000, about 2,000 to about 4,000, or about 3,000 to about 4,000. In some cases, the graphene oxide membrane has a separation factor of about 100, about 200, about 500, about 1,000, about 2,000, about 3,000, or about 4,000. In some cases, the separation factor is measured at 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, or 80 ℃.

In some cases, the graphene oxide membrane has a water flux rate of at least 1000 g·m ^- ²·h ^-1. In some cases, the graphene oxide membrane has a water flux rate of about 1,000 g·m ^- ²·h ^-1 to about 160,000 g·m ^-2·h ^-1. In some cases, the graphene oxide membrane has a water flux rate of at least about 1,000 g·m ^-2·h ^-1. In some cases, the graphene oxide membrane has a water flux rate of at most about 160,000 g·m ^-2·h ^-1. In some cases, the graphene oxide membrane has a water flux rate of about 1,000 g·m ^-2·h ^-1 to about 5,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 10,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 20,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 50,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 100,000 g·m ^-2·h ^-1, about 1,000 g·m ^- ²·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 1,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 10,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 20,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 50,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 100,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1 to about 160,000 g·m ^- ²·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 20,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 50,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 100,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1, about 20,000 g·m ^-2·h ^-1 to about 50,000 g·m ^-2·h ^-1, about 20,000 g·m ^- ²·h ^-1 to about 100,000 g·m ^-2·h ^-1, about 20,000 g·m ^-2·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 20,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 20,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^- ¹, about 50,000 g·m ^-2·h ^-1 to about 100,000 g·m ^-2·h ^-1, about 50,000 g·m ^-2·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 50,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 50,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1, about 100,000 g·m ^-2·h ^-1 to about 120,000 g·m ^-2·h ^-1, about 100,000 g·m ^-2·h ^- ¹ to about 140,000 g·m ^-2·h ^-1, about 100,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1, about 120,000 g·m ^-2·h ^-1 to about 140,000 g·m ^-2·h ^-1, about 120,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1, or about 140,000 g·m ^-2·h ^-1 to about 160,000 g·m ^-2·h ^-1. In some cases, the graphene oxide membrane has a water flux rate of about 1,000 g·m ^-2·h ^-1, about 5,000 g·m ^-2·h ^-1, about 10,000 g·m ^-2·h ^-1, about 20,000 g·m ^-2·h ^-1, about 50,000 g·m ^-2·h ^-1, about 100,000 g·m ^-2·h ^-1, about 120,000 g·m ^-2·h ^-1, about 140,000 g·m ^-2·h ^-1, or about 160,000 g·m ^-2·h ^-1.

In some cases, the graphene oxide membrane comprises permeation defects. In some cases, the permeation defects comprise hydrophilic sites on edges of the permeation defects. In some cases, the hydrophilic sites comprises molecules with hydrophilic functional groups. In some cases, the graphene oxide membrane has a density of permeation defects less than 5%, 4%, 3%, 2%, or 1%. In some cases, the graphene oxide membrane has a density of permeation defects less than 1%.

In some cases, the organic solvent comprises an aldehyde. In some cases, the aldehyde comprises methanol, ethanal, propanal, butanal, phenylmethanal, or any combination thereof. In some cases, the organic solvent comprises an amide. In some cases, the amide comprises acetamide, benzamide, dimethylformamide, dimethylacetamide, or any combination thereof. In some cases, the organic solvent comprises dimethyl sulfoxide (DMSO) or N-Methyl-2-pyrrolidone. In some cases, the organic solvent comprises an alcohol. In some cases, the alcohol comprises methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or any combination thereof.

In another aspect, the present disclosure further relates to a method for vapor permeation, comprising a) passing a feed vapor stream comprising water and an organic solvent through the graphene oxide membrane disclosed herein; and b) separating a permeate stream comprising water from the feed vapor stream. In some cases, the graphene oxide membrane has a separation factor of at least 100 and a water flux rate of at least 1000 g·m ^-2·h ^-1.

In another aspect, the present disclosure further relates to a method for preparing a graphene oxide membrane, comprising contacting a graphite powder with at least one oxidizing agent to generate a first composition comprising graphene oxide, and drying the first composition on a supporting layer to generate the graphene oxide membrane.

In some cases, the drying the first composition comprises vacuum-filtering or spreading the first composition on the supporting layer. In some cases, the at least one oxidizing agent comprises oxygen (O ₂) , ozone (O ₃) , hydrogen peroxide (H ₂O ₂) , Fenton’s reagent, fluorine (F ₂) , chlorine (Cl ₂) , bromine (Br ₂) , iodine (I ₂) , nitric acid (HNO ₃) , sulfuric acid (H ₂SO ₄) , peroxydisulfuric acid (H ₂S ₂O ₈) , peroxymonosulfuric acid (H ₂SO ₅) , chlorite, chlorate, perchlorate, hypochlorite, bleach (NaClO) , chromic acid, dichromic acid, chromium trioxide, pyridinium chlorochromate (PCC) , potassium permanganate, sodium perborate, nitrous oxide (N ₂O) , nitrogen dioxide (NO ₂) , dinitrogen tetroxide (N ₂O ₄) , potassium nitrate (KNO ₃) , sodium bismuthate, or any combination thereof. In some cases, the at least one oxidizing agent comprises sulfuric acid, potassium permanganate, and hydrogen peroxide.

In some cases, a weight ratio of graphite powder to potassium permanganate less than 1: 4, 1: 5, 1: 6, 1: 7, 1: 8, 1: 9 or 1: 10 is used. In some cases, a reaction temperature of less than 40 ℃, 35 ℃, 30 ℃, 25 ℃, 20 ℃, or 15 ℃ is used for contacting the graphite powder with the at least one oxidizing agent.

In some cases, the graphene oxide membrane comprises permeation defects. In some cases, the permeation defects comprise hydrophilic sites on edges of the permeation defects. In some cases, the hydrophilic sites comprise molecules with hydrophilic functional groups.

The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a flow diagram of a method for forming a vapor permeation device, according to an exemplary embodiment of the present disclosure;

FIG. 1B is a flow diagram of a method for forming a vapor permeation device, according to an exemplary embodiment of the present disclosure;

FIG. 2 is a process of a method for separating vapors using a vapor permeation device, according to an exemplary embodiment of the present disclosure;

FIG. 3A is a schematic diagram for a vapor permeation experiment using a thermogravimetric-mass spectrometer combined system, according to an exemplary embodiment of the present disclosure;

FIG. 3B is a graphical illustration of a leak test for vapor permeation chamber, wherein a 20: 80 wt. %water/ethanol mixture was used as the vapor source, according to an exemplary embodiment of the present disclosure;

FIG. 3C is a graphical illustration of a calibration between thermogravimetric analysis and mass spectrometry for pure water, according to an exemplary embodiment of the present disclosure;

FIG. 3D is a graphical illustration of a calibration between thermogravimetric analysis and mass spectrometry for pure ethanol, according to an exemplary embodiment of the present disclosure;

FIG. 3E is a graphical illustration of vapor permeation through a vapor permeation graphene oxide (VPGO) membrane, a normal graphene oxide (NGO) membrane, and a reduced VPGO membrane as measured by thermogravimetric analysis, according to an exemplary embodiment of the present disclosure;

FIG. 3F is an illustration of slip length of VPGO membranes and NGO membranes for the permeation of pure water vapor, according to an exemplary embodiment of the present disclosure;

FIG. 3G is a graphical illustration of lateral size distribution of a VPGO membrane, where average lateral size of the VPGO membrane is 4.46 μm, according to an exemplary embodiment of the present disclosure;

FIG. 3H is a graphical illustration of lateral size distribution of a NGO membrane, where average lateral size of the VPGO membrane is 5.32 μm, according to an exemplary embodiment of the present disclosure;

FIG. 3I is an optical microscopy image obtained for a VPGO membrane, according to an exemplary embodiment of the present disclosure;

FIG. 3J is an optical microscopy image obtained for a NGO membrane, according to an exemplary embodiment of the present disclosure;

FIG. 4A is a graphical illustration of flux as a function of temperature for binary vapors, according to an exemplary embodiment of the present disclosure;

FIG. 4B is a graphical illustration of separation factor as a function of temperature for binary vapors, according to an exemplary embodiment of the present disclosure;

FIG. 4C is a graphical illustration of partial pressure of alcohols in feed vapor as a function of temperature, according to an exemplary embodiment of the present disclosure;

FIG. 4D is a graphical illustration of alcohol flux through a VPGO membrane as a function of temperature, according to an exemplary embodiment of the present disclosure;

FIG. 5A is a graphical illustration of a ratio of vapor pressure of water (P _v, w) and alcohols (P _v, wa) in different feed vapor streams, according to an exemplary embodiment of the present disclosure;

FIG. 5B is a graphical illustration of a ratio of partial pressure of water (P _t, w) and alcohols (P _t, a) in different feed vapor streams, according to an exemplary embodiment of the present disclosure;

FIG. 6 is a graphical illustration of a relationship between flux and separation factor for the separation of a water-ethanol binary vapor by different separation membranes, according to an exemplary embodiment of the present disclosure;

FIG. 7A is a graphical illustration of flux of water and alcohols as a function of Hansen Solubility Parameter (HSP) distance, according to an exemplary embodiment of the present disclosure;

FIG. 7B is a graphical illustration of separation factor for alcohols as a function of HSP distance, according to an exemplary embodiment of the present disclosure;

FIG. 7C is a graphical illustration of a relationship between total flux and HSP distance for different feed vapor streams, according to an exemplary embodiment of the present disclosure;

FIG. 7D is a graphical illustration of a relationship between separation factor and HSP distance for different feed vapor streams, according to an exemplary embodiment of the present disclosure;

FIG. 7E is a graphical illustration of Hansen Solubility Parameter (HSP) distance (Ra) between water and alcohols based on temperature, according to an exemplary embodiment of the present disclosure;

FIG. 8A is a graphical illustration of water and alcohol flux as a function of interlayer distance of a VPGO membrane at 40℃, according to an exemplary embodiment of the present disclosure;

FIG. 8B is a graphical illustration of interlayer distance of a VPGO membrane as a function of feed vapor stream composition, according to an exemplary embodiment of the present disclosure;

FIG. 8C is a graphical illustration of slip length of water as a function of interlayer distance, according to an exemplary embodiment of the present disclosure;

FIG. 8D is a graphical illustration of separation factor as a function of interlayer distance of a VPGO membrane at 40℃, according to an exemplary embodiment of the present disclosure;

FIG. 8E is a graphical illustration of flow velocity of water and alcohols as a function of interlayer distance, according to an exemplary embodiment of the present disclosure;

FIG. 8F is an illustration of hindrance effect of alcohol against fast water transport, according to an exemplary embodiment of the present disclosure;

FIG. 8G is a graphical illustration of x-ray diffraction measurements for a VPGO membrane in different water-alcohol mixtures, where the VPGO membrane was immersed into 20:80 wt. %water-alcohol mixture solutions, according to an exemplary embodiment of the present disclosure;

FIG. 8H is a graphical illustration of interlayer distance as affected by kinetic diameter, according to an exemplary embodiment of the present disclosure;

FIG. 8I is a graphical illustration of measured alcohol flux (squares) and a theoretical flux with Hagen-Poiseuille model under no-slip condition (dashed line) , according to an exemplary embodiment of the present disclosure;

FIG. 8J is a graphical illustration of flux of water and alcohols through a VPGO membrane as a function of alcohol viscosity, according to an exemplary embodiment of the present disclosure; and

FIG. 8K is a graphical illustration of separation factor of a VPGO membrane as a function of alcohol viscosity, according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Definitions

The term “a” or “an” refers to one or more of that entity, i.e. can refer to plural referents. As such, the terms “a, ” “an, ” “one or more, ” and “at least one” are used interchangeably herein. In addition, reference to “an element” by the indefinite article “a” or “an” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there is one and only one of the elements.

Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device or the method being employed to determine the value, or the variation that exists among the samples being measured. Unless otherwise stated or otherwise evident from the context, the term “about” means within 10%above or below the reported numerical value (except where such number would exceed 100%of a possible value or go below 0%) . When used in conjunction with a range or series of values, the term “about” applies to the endpoints of the range or each of the values enumerated in the series, unless otherwise indicated. As used in this application, the terms “about” and “approximately” are used as equivalents.

Graphene oxides (GO) in a laminated arrangement, also known as GO membranes, whose hydrophilic nature readily allows water to permeate the membrane via angstrom-level channels, can be used as separation membranes. Practically, GO membranes are useful for their ease of fabrication, mechanical strength, chemical stability, and flexibility, even for submicron-thick films.

For the separation of water from a mixture solution (e.g. organic solvent-water mixture) by pervaporation, the separation mechanism of the GO membranes relate to preferential absorption of water on its surface owing to the hydrophilic characteristics of GO membranes and the following diffusion of water or transport of condensed water through its angstrom-level channels. In fact, GO membranes are particularly attractive for organic solvent dehydration. GO-based membranes, commonly expressed in terms of separation factor, have demonstrated superior separation factors to that of conventional pervaporation membranes. The ultrafast water transport phenomena caused by low frictional water flow inside GO membranes ensures high water flux during separation.

Vapor permeation processes, conversely, have the advantage that no phase change occurs during permeation from the feed to the permeate side. Thus, the pervaporation-related problem of supplying heat of vaporization can be avoided and the concentration polarization on the feed side of the membrane can become a less critical factor in the vapor permeation process.

GO membranes developed for organic solvent dehydration can be used on pervaporation processes to separate binary and/or multi-component liquid mixtures. However, few investigations directed to binary vapor separation through atomic-scale channels of GO membrane have been reported. Accordingly, the present disclosure describes improved GO membranes that address the above-described shortcomings of previous membrane systems.

To this end, the present disclosure describes processes of binary or multi-component vapor permeation through GO membranes.

Embodiments of the present disclosure investigate the permeation of binary vapor consisting of water and alcohols through a GO membrane. The mechanism for vapor separation is discussed and measured by a combined system of thermogravimetric analysis (TGA) and mass spectrometer (MS) .

In an embodiment, the present disclosure describes a GO membrane for vapor permeation, referred to herein as a vapor permeation-graphene oxide (VPGO) membrane. The VPGO membrane enables increased water transport through graphitic domains when compared to normal GO membranes, resulting in a longer slip length. Due to the hydrophilicity of the VPGO membrane, the VPGO membrane allows for rapid transport of pure water while muting transport of ethanol.

Experimental results of the VPGO membrane of the present disclosure demonstrate high flux and separation factor for water-ethanol vapor separation. In fact, resulting flux of water is more than an order of magnitude higher than that reported previously for traditional polymeric membranes used in vapor permeation. For instance, VPGO membranes can provide high flux (11,000 g m ^-2 h ^-1) and a separation factor over 500 for water-ethanol vapor separation.

With reference now to the Drawings, FIG. 1A and FIG. 1B provide flow diagrams of a method for forming a vapor permeation device. The vapor permeation device may comprise the VPGO membrane of the present disclosure. Briefly, according to an embodiment and as in FIG. 1A, the VPGO membrane may be fabricated by reacting graphite powder with at least one oxidizing agent (at step 105 of method 100) , dispersing the oxidized graphite powder within a base solution (at step 110 of method 100) , and drying the dispersion in order to obtain graphene oxide (at step 115 of method 100) . By the oxidation of the graphite powder using the at least one oxidizing agent, oxygenated functionalities are introduced in the structure of the graphite, thereby expanding layer separation and resulting in a hydrophilic material. For instance, Hummers’ method and Offerman’s method, among others, as well as variations thereof, may be used.

Specifically, a VPGO membrane according to the present disclosure can be fabricated with reference to method 120 of FIG. 1B. A modified Hummers’ method may be used. At sub process 125 of method 120, graphite powder is reacted with at least one oxidizing agent. In an embodiment, the at least one oxidizing agent comprises oxygen (O ₂) , ozone (O ₃) , hydrogen peroxide (H ₂O ₂) , Fenton’s reagent, fluorine (F ₂) , chlorine (Cl ₂) , bromine (Br ₂) , iodine (I ₂) , nitric acid (HNO ₃) , sulfuric acid (H ₂SO ₄) , peroxydisulfuric acid (H ₂S ₂O ₈) , peroxymonosulfuric acid (H ₂SO ₅) , chlorite, chlorate, perchlorate, hypochlorite, bleach (NaClO) , chromic acid, dichromic acid, chromium trioxide, pyridinium chlorochromate (PCC) , potassium permanganate, sodium perborate, nitrous oxide (N ₂O) , nitrogen dioxide (NO ₂) , dinitrogen tetroxide (N ₂O ₄) , potassium nitrate (KNO ₃) , sodium bismuthate, or any combination thereof. In an example, the at least one oxidizing agent comprises sulfuric acid, potassium permanganate, and hydrogen peroxide. First, the graphite powder is dispersed in sulfuric acid. While maintaining a temperature of less than 50℃ (e.g., about 40℃, about 30℃, about 20℃, about 10℃, or about 5℃) , potassium permanganate is added to the dispersion of graphite powder and sulfuric acid. In an embodiment, a weight ratio of graphite powder to potassium permanganate is less than 1: 4. The resulting dispersion is reacted, or oxidized, for a predetermined length of time at a temperature of less than 50℃ (e.g., about 40℃, about 30℃, about 20℃, about 10℃, or about 5℃) . In an example, the reaction temperature is about 30℃. At step 130 of method 120, the reacted dispersion of oxidized graphite powder and oxidizing agents is then poured over ice and hydrogen peroxide is added in order to ensure the reaction is stopped. When gas evolution is completed, GO is obtained at sub process 135 of method 120 by filtering the reaction mixture to, inter alia, remove larger particles. The filtered mixture can then be dispersed in base solution and the resulting GO solution can be sonicated, or exfoliated, to separate unreacted graphite from GO. A supernatant of the sonicated GO solution can then be filtered and, finally, dried in order to obtain graphene oxide. In an embodiment, the sonicated and filtered GO solution can be dried without a support layer, with a support layer, or a combination thereof. No support layer may be used, for instance, when the GO membrane is expected to be of a sufficient thickness (e.g., hundreds of nm or μm) . In an embodiment, the support layer may be a porous membrane. In an embodiment, the support layer may be polysulfone, nylon, anodic aluminum oxide, and the like. After drying, the resulting graphene oxide has a nearly intact σ-framework of C-atoms. In an embodiment, a thickness of the resulting graphene oxide is less than 1 μm (e.g., about 0.75 μm, about 0.50 μm, about 0.33 μm, about 0.25 μm, about 0.10 μm, about 0.01 μm, about 0.001 μm, or about 0.00034 μm) .

Inherent to any crystalline material, including graphene-based structures, is the presence of defects within the lattice thereof. In graphene and graphene-based structures, varieties of defects are unavoidably produced during the preparation process. Moreover, defects can have a significant impact on properties of crystals and nanostructures and can affect the mechanical properties as well as fluid, thermal, and electrical conductivities. As a result, a good understanding of defects and impurities in graphene are useful for accounting for limitations and constraints of graphene-based structures as well as for improving graphene-based structures.

Defects within VPGO membranes, which may be referred to herein as permeation defects, can provide hydrophilic sites. Generally, hydrophilic functional groups within VPGO membranes allow for selective absorption of water in the mixture and flow of water therethrough. However, hydrophilic functional groups present at defect sites within VPGO membranes can cause friction against water transport. Thus, permeation defects can (1) hinder fast water transport and, (2) based on the size of the permeation defects, allow unwanted molecules to permeate the VPGO membrane. For example, larger permeation defects may allow for the unwanted transport of ethanol from a water-ethanol mixture.

With this motivation, the VPGO membranes of the present disclosure are synthesized in order to suppress the creation of permeation defects, and thus permeation defect-proximate hydrophilic groups, while permitting hydrophilic functional groups on the basal plane. In practical terms, friction sites against water transport are decreased while the VPGO membrane retains the capability to selectively absorb water. As a result, it can be considered that VPGO membranes, according to embodiments of the present disclosure, comprise a structure allowing for fast water transport.

It can, therefore, be appreciated that water transport (e.g., ballistic transport) through GO membranes (or VPGO membranes) can be limited by the presence of defects. Accordingly, it is important to control the formation of defects to control, to the extent possible, flow behavior across the membrane.

In the present disclosure, a modified Hummers’ method was used to synthesize a VPGO membrane. Density of defects can be measured by, for example, Raman spectroscopy, wherein a crystallinity and defects can be measured based on optical feedback. In an embodiment, a density of defects of the VPGO membrane may be less than 5% (e.g., about 4%, about 3%, about 2%, about 1%, about 0.5%, or about 0.1%) . In an example, a density of defects of the VPGO membrane is about 0.1%. This value can be best appreciated when compared with a corresponding value for a normal GO membrane generated by Hummer method. In the normal GO membrane, the defect density is greater than 5%, indicating that the VPGO membrane of the present disclosure displays an order of magnitude improvement over normal methods.

Structurally, these defect density results suggest that the honeycomb sp ² carbon network of the VPGO membrane is well-preserved. The advantages for the well-preserved carbon network of the VPGO membrane can be appreciated with respect to FIG. 3A through FIG. 3J, which will be described in detail later.

According to an embodiment, a VPGO membrane of the present disclosure may be used for separation of fluids within a feed vapor stream, as in sub process 205 of method 200 shown in FIG. 2. Fluid passing through the VPGO membrane may form a permeation stream. The feed vapor stream may comprise an inorganic solvent and an organic solvent. In an embodiment, a feed vapor stream comprising water and an organic solvent may be brought into contact with the VPGO membrane. The permeation stream passing through the VPGO membrane may substantially comprise water.

In an embodiment, the organic solvent may comprise an aldehyde. In an embodiment, the aldehyde may comprise methanol, ethanal, propanal, butanal, phenylmethanal, or combinations thereof.

In an embodiment, the organic solvent may comprise an amide. In an embodiment, the amide may comprise acetamide, benzamide, dimethylformamide, dimethylacetamide, or combinations thereof.

In an embodiment, the organic solvent may be acetone, ethylene glycol, benzene, or combinations thereof.

In an embodiment, the organic solvent may comprise an alcohol. In an embodiment, the alcohol may comprise methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or combinations thereof.

In an embodiment, the organic solvent comprises dimethyl sulfoxide or N-methyl-2-pyrrolidone.

EXAMPLE

VPGO Membrane Fabrication

For experimentation, the VPGO membrane of the present disclosure is synthesized by a modified Hummers’ method. For instance, 1 kilogram (kg) of graphite powder (100 mesh) was dispersed in 30 liters (L) of concentrated sulfuric acid. The dispersion was then cooled to about 10℃. Subsequently, 3 kg of potassium permanganate, achieving a weight ratio of graphite powder to potassium permanganate of 1: 3, was slowly added, and the resulting dispersion stirred an additional 3 hours (not exceeding 3 hours) at 30℃ (without exceeding 30℃) . The reaction mixture was then poured on 60 kg of ice, and 0.3 L hydrogen peroxide (30%) was added drop wise until gas evolution was completed. Graphene oxide was then obtained by pressure filtration. The filtrate was then dispersed in water via mild sonication to form a GO solution. A supernatant of the GO solution was then vacuum filtered, and a filtrate thereof was dried on a support layer. In an example, the filtrate volume of the GO solution following vacuum filtration was 20 mL (concentration: 0.1 mg/mL) , and the thickness of the VPGO membrane was approximately 0.33 μm, as measured by surface profilometer.

Vapor Permeation Test

In order to evaluate, sequentially, water permeability of the fabricated VPGO membrane and performance of the VPGO membrane as a function of temperature, a vapor permeation analyzer equipped with a mass spectrometer was deployed for performing thermogravimetric analysis. The evaluation facilitates accurate quantitative and component analysis for vapor permeate at the same time. Such an evaluation system is shown in FIG. 3A. The combined measurement system makes it possible to precisely estimate amounts of each component in multi-component or binary vapor permeate and analyze the mechanism of vapor permeation and separation of binary vapor through unique atomic-scale channels of the VPGO membrane and other, referential GO membranes.

To perform the experiment, a μ-pervaporation chamber for vapor permeation experiments was fabricated from stainless steel (SS) . Binary mixture solutions were loaded into the μ-pervaporation chamber. In one example, a 20: 80 wt. %water/alcohol mixture was used as a feed vapor stream. A polytetrafluoroethylene (PTFE) film (thickness: 350 μm) having a 300 μm diameter aperture at its center was used as a gasket. Prior to testing, a leak test was carried out from room temperature to the boiling point of alcohol, where the feed vapor stream includes a 20%water -80%ethanol mixture solution. In the leak test, a PTFE film gasket without an aperture was loaded. No weight loss and variation in mass number (m/z) for water and ethanol was detected in the leak test, as shown in FIG. 3B. Therefore, the weight loss detected during experiments with VPGO membranes could be confidently attributed to permeate passing through the GO membranes.

For each experiment, a VPGO membrane was loaded onto the PTFE gasket and then a SS gasket with a 1.2 mm diameter aperture at its center, and a corresponding SS lid, was placed on the VPGO membrane. Finally, all were tightly locked with screw bolts.

All experiments were carried out under N ₂ atmosphere. First, before performing vapor permeation experiment, a calibration between thermogravimetric analyses and mass spectrometer was conducted via the pin hole method. The calibration enabled, via mass spectrometry data, the analysis of an amount of each component in the permeate. For calibration, pure solutions consisting of binary mixtures was loaded in the μ-pervaporation chamber as a vapor source. During calibration, the evaporated weight of the components was controlled by limiting the evaporation area. In other words, the evaporated weight was controlled by limiting the hole size of the PTFE film gasket. Calibrations, like the leak test, were performed in the absence of VPGO membranes.

Results from the calibration experiment yielded calibration data, as shown in FIG. 3C and FIG. 3D, for water and ethanol in the range from room temperature to 95 ℃ and from room temperature to 85 ℃. Mass numbers measured according to variation of weight losses (i.e., evaporated amount as measured via thermogravimetric analysis) for water and ethanol was measured via mass spectrometer. Subsequently, the amount of water and ethanol in the permeate was analyzed alongside mass spectrometer data for pure water and ethanol when the water-ethanol binary vapor was measured.

Following successful calibrations, and returning now to FIG. 3E and FIG. 3F, experiments were performed to compare permeate component flux for different membrane types. The membranes assessed included an open aperture, a VPGO membrane according to embodiments of the present disclosure, a normally prepared GO (NGO) membrane, and a reduced VPGO membrane. Reduced VPGO membranes a form of VPGO membrane that has been processed by chemical, thermal, and other methods in order to reduce the oxygen content. Experiments were performed at 40℃ under atmospheric pressure. As shown in FIG. 3E, water vapor flux through VPGO membranes is an order of magnitude greater than that for NGO membranes. Comparatively, ethanol (EtOH) flow through the VPGO membrane was low. Flux was calculated as

where M _permeate is mass (g) of permeate (i.e., weight loss measured from thermogravimetric analysis) , A is membrane area (m ²) , and t is measurement time (hr) . The flux includes water flux and alcohol flux.

High flux through VPGO membranes can be attributed to enhanced slip flow in VPGO membranes, as shown in FIG. 3F, where a given VPGO membrane exhibits a two order longer slip length than that of an NGO membrane. The slip length, a measure of non-frictional flow when the permeate passes through a membrane, will be described in greater detail later.

The results from FIG. 3E and FIG. 3F confirm that water and organic solvents, including alcohols, are involved in capillary flow and viscous flow through GO membranes, respectively. This means that water provides advantages for rapid transport through GO membranes. Previous studies suggest capillary pressure as a driving force for water permeation in GO membranes is greater than 1000 bar in GO membranes. Capillary pressure in a VPGO membrane prepared according to embodiments of the present disclosure is about 1200 bar. Thus, it can be appreciated that fast water transport through VPGO membranes can be realized, enabled, in part, by a long slip length and high capillary pressure.

Briefly, supporting information for is shown in FIG. 3G through FIG. 3J. For FIG. 3G and FIG. 3H, the distributions were obtained from optical microscopy measurements of over 200 individual graphene oxide sheets coated on silicon dioxide substrate. The distributions are, generally, Gaussian-distributed. For FIG. 3I and FIG. 3J, the graphene oxide sheets were coated on silicon oxide substrates through Langmuir-Blodgett method. Only single layer sheets in the microscopy images were counted to measure the lateral size shown in FIG. 3G and FIG. 3H.

Temperature dependent performance of the VPGO membrane were evaluated, as shown in FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D. Briefly, results indicate that VPGO membranes exhibit a trade-off behavior between the flux and separation factor in response to a change in temperature. For instance, flux increases with an increase in temperature (see FIG. 4A) while separation factor (see FIG. 4B) decreases. Moreover, flux (see FIG. 4A) and separation factor (see FIG. 4B) are different among different binary vapors.

The trade-off behavior may be explained by a change in the driving force (e.g., partial pressure) in the feed vapor stream, wherein partial pressures of alcohols increase with increasing temperature, as shown in FIG. 4C. This is particularly relevant to the separation factors shown in FIG. 4B. The trade-off behavior may also be explained by the amount of alcohol (e.g., MeOH, EtOH, IPA, BuOH, PeOH) that permeates through the membrane as the temperature is increased (see FIG. 4D) . An increase in temperature leads to an increase in vapor pressure of alcohols within the feed vapor stream, the vapor pressure being defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The vapor pressure generally increases, which indicates the partial pressure (i.e., concentration) of alcohols in the feed vapor stream increases. According to Fick’s law of diffusion in gas, particularly in a homogenous vapor stream, the partial pressure of each component is the driving force for diffusion, where the diffusion rate is defined by

and N _A is the diffusion rate of gas A, D is the diffusion coefficient of gas A, R is the universal gas constant, T is temperature (Kelvin) , dP is the partial pressure of gas A, and dx is the characteristic length of the membrane.

In a binary feed vapor stream, however, the partial pressure of water also increases with temperature. Thus, considering that the ratio of the partial pressure between water and alcohols with temperature does not significantly change, as shown in FIG. 5A and FIG. 5B, the increase in partial pressure of alcohols in the binary feed vapor stream is not likely the main reason for the results described above. In other words, GO membranes would selectively absorb water from the binary feed vapor stream, due to its hydrophilicity, even when the partial pressure of alcohols increases on the feed side of the membrane.

The trade-off behavior may also be explained by the change of interlayer distance according to temperature. The interlayer distance of a GO membrane in aqueous solution is determined by the thickness of the Debye length λ _D, which can be modeled by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory as

where ε _s is the dielectric constant of solution, ε ₀ the vacuum permittivity, k the Boltzmann constant, T the absolute temperature, N _A Avogadro’s number, e the electron charge, and I the ionic strength of the bulk solution.

The model by DLVO theory is applicable to vapor permeation through GO membranes. According to the model, the thickness of the Debye length, λ _D, is proportional to the temperature. Theoretically, it is expected that the interlayer distance can increase with temperature rise, thereby contributing to an increase of the flux with temperature. Moreover, calculating a change of water flux according to interlayer distance at fixed slip length supports these results.

Further to the above, FIG. 6 is a graphical illustration of the relationship between flux and separation factor for a water/ethanol binary vapor exposed to presently-available membranes (e.g., polymeric membranes) and the VPGO membranes of the present disclosure, appreciating that graphene oxide-based membranes for vapor permeation have not yet been reported. In FIG. 6, circles represent conventional polymer membranes, triangles represent inorganic membranes, and rectangles represent VPGO membranes.

The separation factor (SF) was calculated as

where F _water is the mass (g) of water vapor in the feed vapor stream, P _alcohol is the mass (g) of alcohol vapor in the feed vapor stream, P _water is the mass of water vapor in the permeate stream, and P _alcohol is the mass (g) of alcohol vapor in the permeate stream. The mass of water vapor and alcohol vapor in the permeate stream was calculated by the mass spectrometer data through the calibration data for each component. The water contents in permeate was calculated as follows:

Limitations of polymeric membranes are observed in flux. Though certain polymeric membranes demonstrate good separation factors, polymeric membranes generally exhibit flux around 1,000 g m ^-2 h ^-1. This may be expected as polymeric membranes often display weak chemical resistance and thermal stability. Chemical resistance of membranes for vapor permeation is a critical factor as the membranes are mainly exposed to alcohols and solvents vapor. For this reason, inorganic membranes have been recently studied due to their excellent chemical resistance, mechanical strength, and thermal stability. While inorganic membranes exhibit improved performance when compared with polymeric membranes, in particular as it relates to flux, inorganic membranes are difficult to machine (due to brittleness) and are costly. Accordingly, VPGO membranes represent a significant improvement. As shown in FIG. 6, VPGO membranes exhibit high flux along with high separation factor. For instance the separation factor of a VPGO membranes may be greater than 100, about 200, about 300, about 400, about 500, or about 1000. With respect to flux, VPGO membranes result in flux an order of magnitude higher than polymeric membranes.

FIG. 6 illustrates why graphene oxide is a very fascinating material as a membrane for vapor permeation. VPGO membranes exploit the advantages of each of polymeric membranes and inorganic membranes, such as excellent chemical resistance and mechanical strength and easy fabrication and good thermal stability.

The trade-off behavior demonstrated for VPGO membranes in FIG. 4A and FIG. 4B has particular relevance to the intramolecular interaction between water molecules and alcohol molecules. This can be explained, in part, by a solubility parameter. Hansen Solubility Parameter (HSP) , for instance, is a method of predicting if one material will dissolve in another and form a solution. The HSP distance between two molecules, conventionally called Ra, is the difference in HSP between two substances and is a measure of how alike they are. The smaller the Ra, the more likely they are to be compatible. Understanding the HSP distance between water and alcohols can help to explain, in particular, changes in the separation factor with temperature, as shown in FIG. 4B. Such a relationship can generally be referred to as cooperative permeation. Cooperative permeation indicates that two molecules interact strongly when the HSP distance is shorter and, as a result, and as shown in FIG. 7A, alcohol permeates at a higher rate. A similar scenario can be observed with separation factor, as shown in FIG. 7B. Together, a smaller HSP distance indicates higher compatibility of water and alcohols.

Therefore, it must be considered that water vapor in the feed vapor stream generates condensed water layers into the interlayer space and certain alcohol molecules interact with the condensed water layers. As a result, water delivers alcohols together in the process of the vapor permeation through the GO membranes ( “cooperative permeation” ) . MeOH and EtOH molecules can trigger stronger cooperative permeation than other alcohols at fixed temperature. This is shown in FIG. 7C and FIG. 7D. With that, HSP distance decreases in all binary vapors in response to temperature rise, as shown in FIG. 7E. Thus, an enhancement of compatibility between the molecules demonstrates that flux and separation factor are dependent on the change of HSP distance according to temperature.

FIG. 8A through FIG. 8F illustrate the relationship between interlayer distance and flux, slip length, separation factor, and flow velocity, among others, wherein interlayer distance is an indication of a size of channels within the VPGO membranes.

As in FIG. 8A, the flux of water and alcohols was separated from the measured total flux and was shown to be dependent on the interlayer distance. FIG. 8B demonstrates changes in interlayer distance of VPGO membranes in the presence of solvent mixtures. FIG. 8G demonstrates the impact of different solvent mixtures on x-ray diffraction data. The interlayer distance was measured with a water-alcohol mixture solution, appreciating that vapor builds condensed layers, like the bulk phase, into the interlayer space of a VPGO membrane. It can be observed that the interlayer distance of a VPGO membrane is changeable in view of different binary vapors. Such adjustability can be explained by kinetic diameter of alcohol molecules, as shown in FIG. 8H, wherein the kinetic diameter of 1-pentanol is assumed to be identical to 1-butanol (in analogy with the linear alkanes, where n-pentane has the same kinetic diameter as n-butane) . It is known that VPGO membranes, due to their hydrophilicity, can preferentially absorb water molecules from the binary vapor. However, if only water in the binary vapor is absorbed and then diffused through the VPGO membrane, the interlayer distance would not change in the presence of different solvent mixtures. This is not realized in FIG. 8B, though, indicating intercalation of a small amount of alcohol molecules into the interlayer spacing by interacting with water molecules. It is also possible that cooperative permeation, described above, plays a role. The interlayer spacing may be manipulated by preferentially absorbing water on the GO membrane, thereby allowing alcohol permeation through the interlayer spacing with the interaction of two molecules.

In an example, interlayer spacing of a normal GO membrane, generated by Hummer’s method, increases from 8.6 Angstroms, in a dry state, to 12.1 Angstroms, when contacted with water. This can be directly compared with interlayer spacing of a VPGO membrane, generated by methods of the present disclosure, which increases from 9 Angstroms, in a dry state, to 11.7 Angstroms, when contacted with water. Such a comparison shows a smaller interlayer spacing for VPGO membranes in water, thereby allowing for improved separation of water from a binary vapor, as can be appreciated from the above discussions.

Further, it can be appreciated from FIG. 8A that the reduction of the water flux is larger than that of the scaling of the flux. The scaling of the flux (φ) with the interlayer distance should be φ～δ ²·λ where δ is interlayer distance and λ is a slip length. The scaling to calculate slip length (λ) can be used as a function of interlayer distance (δ) . Slip length was calculated using an indirect method and defined as

where

is an enhancement factor, Q _slip is a flow rate with a slip boundary condition, Q _no-slip is a flow rate with a no-slip boundary condition, λ is the slip length, and δ is the pore size. Q _slip can be matched with the experimentally observed flow rate when choosing the slip length, λ. Interlayer distance was used as the pore size. Assuming water inside the interlayer space behaves as a classic liquid, the Hagen-Poiseuille equation for Q _no-slip is

where Δp is the pressure, ρ is the bulk water density, η is water viscosity (mPa·s) , L is the channel width and l is the channel length (i.e., permeation length) . The channel length, l, is calculated by N×L. N is a number of turns of a GO sheet and L is a width of a GO sheet, where N=h/d, h being a thickness of the VPGO membrane and d being an interlayer distance. The interlayer distance of a VPGO membrane and of an NGO membrane, in a wetted state, was measured by X-ray diffraction. For calculation of the pressure, Δp, the capillary pressure is assumed to be generated in the interlayer space of the GO membrane. Thus, Δp can be replaced by capillary pressure (P _c) , the capillary pressure in GO membranes being calculated using the Young-Laplace equation as

where P _c is the capillary pressure, γ is the water-air interfacial tension, θ is the wetting angle, and r is half of the interlayer distance. θ is assumed to be zero.

In view of FIG. 8A, it can be appreciated that the water flux from binary vapor with methanol is not significantly reduced when compared with that of pure water flux. Water flux from the binary vapor with other alcohols, however, impacts the scaling of flux. Based on these results, it can be said that a significant volume of the channel is filled with water, meaning that a high flux of MeOH is not driven by high filling of MeOH molecules into the channel, where flux is approximately equal to a number of particles multiplied by velocity. Rather, the high flux of MeOH is likely due to a high velocity of MeOH molecules, as shown in FIG. 8E. Hence, it can be suggested that cooperative fast transport occurs in nanochannels of the GO membranes. Moreover, it cannot be explained by conventional viscous flow of organic solvents for GO membranes. The flux of alcohols is much higher than that calculated with Hagen-Poiseuille model under a no-slip condition, as shown in FIG. 8I. This also supports the theory of cooperative fast permeation. For other binary vapors, it is expected that higher water filling and slower cooperative transport result in lower flux than that with MeOH, in accordance with FIG. 8A. Different slip lengths of water, as shown in FIG. 8C, may indicate the velocity difference of the cooperative transport, although it is expected the slip length of water cannot be changed, given its physical definition (i.e., moving distance of water molecules without any friction between water molecules and GO sheets) . The slip length of water in the binary vapor with PeOH is much lower than slip length of pure water

The hindrance effects of alcohols to fast water transport may impact the channels. A trace of alcohol molecules can get into the channel (i.e., the interlayer space) of the GO membrane through the interaction with water molecules even though alcohol molecules cannot enter the channels alone. The relative difference in the flow velocity between water and alcohols, attributable to the different flow modes mentioned above (e.g., slip flow for water and viscous flow for alcohols) , is shown in FIG. 8E. The alcohol molecules clog a part of the channel while moving slowly and retarding fast water transport due to their relatively slow velocity in the channel, as shown in FIG. 8F, where δF indicates intermolecular forces between water and alcohol molecules (e.g., dispersion and dipolar force, hydrogen bonds, etc. ) . For instance, PeOH exhibits the slowest velocity among the alcohols. It slows water velocity more than other alcohols and, as a result, causes the change of slip length of water. In the binary vapor permeation, the hindrance effect of alcohol molecules restricts ballistic water transport in the channel of the GO membrane. Thus, it is critical to determine the water transport into the atomic-scale channel of the GO membrane. The hindrance effect also leads to visco-selectivity, or dependency of the flux and separation factor of the membrane on the viscosity of alcohols exposed thereto, as shown in FIG. 8J and FIG. 8K.

The present disclosure demonstrates that a GO membrane can be used to separate a binary vapor including water. A VPGO membrane according to embodiments described herein is attractive for use as a separation membrane. The VPGO membrane allows for selective water permeation from the binary vapor mixture and defect-free characteristic results in fast water transport, thereby presenting its utility as a high-flux membrane for vapor permeation. To this end, it delivers a flux capacity exceeding that of available inorganic and polymeric membranes, achieving a level of 10 ⁴ gMH for an ethanol-water binary vapor, almost an order of magnitude greater than that attainable by traditional membranes.

The VPGO membrane represents a new class of membrane for vapor permeation. The present disclosure demonstrates that a high performance GO membrane for vapor permeation can be generated by controlling hydrophilicity, interlayer distance, and defect density of the GO membrane. Based on the above and traditional theory for capillary force, enhancing hydrophilicity of GO membranes for selective water permeation, reducing defect density to trigger fast water flow, and narrowing interlayer space in order to increase the capillary force for fast water permeation. In this way, the separative ability of GO membranes can be controlled.

INCORPORATION BY REFERENCE

All references, articles, publications, patents, patent publications, and patent applications cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

NUMBERED EMBODIMENTS OF THE INVENTION

Notwithstanding the appended claims, the disclosure sets forth the following numbered embodiments:

(1) A vapor permeation device, comprising a graphene oxide membrane, wherein the graphene oxide membrane is configured to separate a permeation stream comprising water from a feed vapor stream comprising water and an organic solvent, and wherein the graphene oxide membrane has a separation factor of at least 100 and a water flux rate of at least 1000 g·m ^-2·h ^-1.

(2) The device of (1) , wherein the graphene oxide membrane comprises permeation defects.

(3) The device of either (1) or (2) , wherein the permeation defects comprise hydrophilic sites on edges of the permeation defects.

(4) The device of any one of (1) to (3) , wherein the hydrophilic sites comprises molecules with hydrophilic functional groups.

(5) The device of any one of (1) to (4) , wherein the graphene oxide membrane has a density of permeation defects less than 5%.

(6) The device of any one of (1) to (5) , wherein the graphene oxide membrane has a density of permeation defects less than 1%.

(7) The device of any one of (1) to (6) , wherein the organic solvent comprises an aldehyde.

(8) The device of any one of (1) to (7) , wherein the aldehyde comprises methanol, ethanal, propanal, butanal, phenylmethanal, or any combination thereof.

(9) The device of any one of (1) to (8) , wherein the organic solvent comprises an amide.

(10) The device of any one of (1) to (9) , wherein the amide comprises acetamide, benzamide, dimethylformamide, dimethylacetamide, or any combination thereof.

(11) The device of any one of (1) to (10) , wherein the organic solvent comprises dimethyl sulfoxide (DMSO) or N-Methyl-2-pyrrolidone.

(12) The device of any one of (1) to (11) , wherein the organic solvent comprises an alcohol.

(13) The device of any one of (1) to (12) , wherein the alcohol comprises methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or any combination thereof.

(14) A method for vapor permeation, comprising passing a feed vapor stream comprising water and an organic solvent through a graphene oxide membrane, wherein the graphene oxide membrane has a separation factor of at least 100 and a water flux rate of at least 1000 g·m ^-2·h ^-1, and b) separating a permeate stream comprising water from the feed vapor stream.

(15) The method of (14) , wherein the organic solvent comprises an aldehyde.

(16) The method of either (14) or (15) , wherein the aldehyde comprises methanol, ethanal, propanal, butanal, phenylmethanal, or any combination thereof.

(17) The method of any one of (14) to (16) , wherein the organic solvent comprises an amide.

(18) The method of any one of (14) to (17) , wherein the amide comprises acetamide, benzamide, dimethylformamide, dimethylacetamide, or any combination thereof.

(19) The method of any one of (14) to (18) , wherein the organic solvent comprises dimethyl sulfoxide (DMSO) or N-Methyl-2-pyrrolidone.

(20) The method of any one of (14) to (19) , wherein the organic solvent comprises an alcohol.

(21) The method of any one of (14) to (20) , wherein the alcohol comprises methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or any combination thereof.

(22) A method for preparing a graphene oxide membrane, comprising contacting a graphite powder with at least one oxidizing agent to generate a first composition comprising graphene oxide, and drying the first composition on a supporting layer to generate the graphene oxide membrane.

(23) The method of (22) , wherein drying the first composition comprises vacuum-filtering or spreading the first composition on the supporting layer.

(24) The method of either (22) or (23) , wherein the at least one oxidizing agent comprises oxygen (O ₂) , ozone (O ₃) , hydrogen peroxide (H ₂O ₂) , Fenton’s reagent, fluorine (F ₂) , chlorine (Cl ₂) , bromine (Br ₂) , iodine (I ₂) , nitric acid (HNO ₃) , sulfuric acid (H ₂SO ₄) , peroxydisulfuric acid (H ₂S ₂O ₈) , peroxymonosulfuric acid (H ₂SO ₅) , chlorite, chlorate, perchlorate, hypochlorite, bleach (NaClO) , chromic acid, dichromic acid, chromium trioxide, pyridinium chlorochromate (PCC) , potassium permanganate, sodium perborate, nitrous oxide (N ₂O) , nitrogen dioxide (NO ₂) , dinitrogen tetroxide (N ₂O ₄) , potassium nitrate (KNO ₃) , sodium bismuthate, or any combination thereof.

(25) The method of any one of (22) to (24) , wherein the at least one oxidizing agent comprises sulfuric acid, potassium permanganate, and hydrogen peroxide.

(26) The method of any one of (22) to (25) , wherein a weight ratio of graphite powder to potassium permanganate less than 1: 4 is used.

(27) The method of any one of (22) to (26) , wherein a reaction temperature of less than 40 ℃ is used for contacting the graphite powder with the at least one oxidizing agent.

(28) The method of any one of (22) to (27) , wherein the graphene oxide membrane comprises permeation defects.

(29) The method of any one of (22) to (28) , wherein the permeation defects comprise hydrophilic sites on edges of the permeation defects.

(30) The method of any one of (22) to (29) , wherein the hydrophilic sites comprise molecules with hydrophilic functional groups.

(31) The method of any one of (22) to (30) , wherein the graphene oxide membrane has a density of permeation defects less than 5%.

(32) The method of any one of (22) to (31) , wherein the graphene oxide membrane has a density of permeation defects less than 1%.

Claims

A vapor permeation device, comprising a graphene oxide membrane, wherein the graphene oxide membrane is configured to separate a permeation stream comprising water from a feed vapor stream comprising water and an organic solvent, and wherein the graphene oxide membrane has a separation factor of at least 100 and a water flux rate of at least 1000 g·m ^-2·h ^-1.
The device of claim 1, wherein the graphene oxide membrane comprises permeation defects.
The device of claim 2, wherein the permeation defects comprise hydrophilic sites on edges of the permeation defects.
The device of claim 3, wherein the hydrophilic sites comprises molecules with hydrophilic functional groups.
The device of claim 2, wherein the graphene oxide membrane has a density of permeation defects less than 5%.
The device of claim 2, wherein the graphene oxide membrane has a density of permeation defects less than 1%.
The device of claim 1, wherein the organic solvent comprises an aldehyde.
The device of claim 7, wherein the aldehyde comprises methanol, ethanal, propanal, butanal, phenylmethanal, or any combination thereof.
The device of claim 1, wherein the organic solvent comprises an amide.
The device of claim 9, wherein the amide comprises acetamide, benzamide, dimethylformamide, dimethylacetamide, or any combination thereof.
The device of claim 1, wherein the organic solvent comprises dimethyl sulfoxide (DMSO) or N-Methyl-2-pyrrolidone.
The device of claim 1, wherein the organic solvent comprises an alcohol.
The device of claim 12, wherein the alcohol comprises methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or any combination thereof.
A method for vapor permeation, comprising:

a) passing a feed vapor stream comprising water and an organic solvent through a graphene oxide membrane, wherein the graphene oxide membrane has a separation factor of at least 100 and a water flux rate of at least 1000 g·m ^-2·h ^-1; and

b) separating a permeate stream comprising water from the feed vapor stream.
The method of claim 14, wherein the organic solvent comprises an aldehyde.
The method of claim 15, wherein the aldehyde comprises methanol, ethanal, propanal, butanal, phenylmethanal, or any combination thereof.
The method of claim 14, wherein the organic solvent comprises an amide.
The method of claim 17, wherein the amide comprises acetamide, benzamide, dimethylformamide, dimethylacetamide, or any combination thereof.
The method of claim 14, wherein the organic solvent comprises dimethyl sulfoxide (DMSO) or N-Methyl-2-pyrrolidone.
The method of claim 14, wherein the organic solvent comprises an alcohol.
The method of claim 14, wherein the alcohol comprises methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, or any combination thereof.
A method for preparing a graphene oxide membrane, comprising:

a) contacting a graphite powder with at least one oxidizing agent to generate a first composition comprising graphene oxide; and

b) drying the first composition on a supporting layer to generate the graphene oxide membrane.
The method of claim 22, wherein drying the first composition comprises vacuum-filtering or spreading the first composition on the supporting layer.
The method of claim 22, wherein the at least one oxidizing agent comprises oxygen (O ₂) , ozone (O ₃) , hydrogen peroxide (H ₂O ₂) , Fenton’s reagent, fluorine (F ₂) , chlorine (Cl ₂) , bromine (Br ₂) , iodine (I ₂) , nitric acid (HNO ₃) , sulfuric acid (H ₂SO ₄) , peroxydisulfuric acid (H ₂S ₂O ₈) , peroxymonosulfuric acid (H ₂SO ₅) , chlorite, chlorate, perchlorate, hypochlorite, bleach (NaClO) , chromic acid, dichromic acid, chromium trioxide, pyridinium chlorochromate (PCC) , potassium permanganate, sodium perborate, nitrous oxide (N ₂O) , nitrogen dioxide (NO ₂) , dinitrogen tetroxide (N ₂O ₄) , potassium nitrate (KNO ₃) , sodium bismuthate, or any combination thereof.
The method of claim 22, wherein the at least one oxidizing agent comprises sulfuric acid, potassium permanganate, and hydrogen peroxide.
The method of claim 25, wherein a weight ratio of graphite powder to potassium permanganate less than 1: 4 is used.
The method of claim 22, wherein a reaction temperature of less than 40 ℃ is used for contacting the graphite powder with the at least one oxidizing agent.
The method of claim 22, wherein the graphene oxide membrane comprises permeation defects.
The method of claim 22, wherein the permeation defects comprise hydrophilic sites on edges of the permeation defects.
The method of claim 22, wherein the hydrophilic sites comprise molecules with hydrophilic functional groups.
The method of claim 22, wherein the graphene oxide membrane has a density of permeation defects less than 5%.
The method of claim 22, wherein the graphene oxide membrane has a density of permeation defects less than 1%.