Patent Publication Number: US-2022212956-A1

Title: Methods for water extraction

Description:
TECHNICAL FIELD 
     The present disclosure is directed to methods for extracting water from aqueous fluids. In one example, the disclosure provides a method for desalinating a saline water, such as an ocean water, by extracting fresh water from the saline water using an organic solvent in which the fresh water is soluble. 
     BACKGROUND 
     Water scarcity is one of the leading crises affecting quarter of the world population. Access to fresh drinking water in the geographic areas where the fresh water is scarce allows to maintain productive economic activities in those areas, and to prevent any regional or international armed conflicts over rights to water resources (“water wars”). 
     Desalination technologies exist to produce fresh water from saline water, with more than 10,000 desalination plants operating around the world. The existing desalination technologies can be subdivided into two general categories: evaporative technologies and non-evaporative technologies. 
     Evaporative technologies include a phase change of the processed water (liquid to vapor, vapor to liquid), where feed saline water is vaporized and then subsequently condensed to produce distilled water. The most common evaporative desalination technologies include multi-stage flash distillation (MSF), multi-effect distillation (MED), and membrane distillation (MD). 
     In contrast, non-evaporative technologies do not include any phase change of water, and focus on physical separation of water from solutes in the liquid phase. Examples of non-evaporative desalination technologies include membrane-based reverse osmosis (RO), nanofiltration (NF), forward osmosis (FO), electric-field driven electrodialysis (ED), and capacitive deionization (CDI). 
     While existing desalination technologies provide some access to fresh water, these existing processes suffer from serious drawbacks. Evaporative technologies, for example, require a lot of energy to heat the saline water to produce a steam of fresh water, and then to cool the steam to produce liquid fresh water. Non-evaporative technologies also include very energy-demanding steps. In these non-evaporative processes, the energy is needed, for example, to create sufficient pressure to push the molecules of water through an osmotic membrane or a nanofilter, leaving behind the salt ions. Hence, due to constantly increasing energy costs, the fresh water produced by existing means is too expensive for many. In addition, non-evaporative technologies, such as reverse osmosis, often require complex proprietary membranes that are difficult and expensive to produce, maintain, and replace as they become blocked. 
     SUMMARY 
     In a general aspect, the present disclosure provides a method of extracting water from a feed liquid containing water, the method including: 
     contacting the feed liquid containing water with a solvent liquid using a porous membrane that is configured to create and maintain a contact between the feed liquid and the solvent liquid, for an amount of time sufficient to allow for a dissolution of water into the solvent liquid; and 
     producing a raffinate containing the feed liquid depleted in water and an extract containing the solvent liquid enriched in water. 
     In some embodiments, the feed liquid is saline water. 
     In some embodiments, saline water is selected from ocean water, seawater, salt-lake water, salt marsh water, brackish water, and briny water. 
     In some embodiments, raffinate includes brine. 
     In some embodiments, the porous membrane is prepared from a hydrophobic material. 
     In some embodiments, the method includes preparing the porous membrane from a hydrophobic material. 
     In some embodiments, the hydrophobic material is selected from polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polymethylpentene, poly(vinyltrimethylsilane), hexafluoropropylene, polysulfone (PSU), polyethersulfone (PES), polyphenylene sulfone (PPSU), and poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP), or a mixture or a copolymer thereof. 
     In some embodiments, porosity of the porous membrane is in a range from about 10% to about 85%. 
     In some embodiments, mean pore size of the porous membrane is in a range from about 10 nm to about 100 μm. 
     In some embodiments, the solvent liquid is hydrophobic and immiscible with the feed liquid. 
     In some embodiments, solubility of water in the solvent liquid is temperature-dependent. 
     In some embodiments, the solvent liquid includes an alkylamine solvent selected from diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), N,N,-dimethylcyclohexylamine (DMCHA), N-methylbutyl amine, diethylmethylamine, and N-ethylpropylamine. 
     In some embodiments, the solvent liquid includes a fatty acid solvent selected from decanoic acid and octanoic acid. 
     In some embodiments, the method includes treating the extract to produce water and the solvent liquid depleted in water. 
     In some embodiments, water is potable water. 
     In a general aspect, the present disclosure provides a method of extracting a solvent phase from a feed liquid containing a solvent phase and a solute dissolved in the solvent phase, the method including: 
     contacting the feed liquid with a solvent liquid using a porous membrane that is configured to maintain a contact between the feed liquid and the solvent liquid for an amount of time sufficient to allow for a dissolution of the solvent phase into the solvent liquid; and 
     producing a raffinate including the feed liquid depleted in the solvent phase and an extract including the solvent liquid enriched in the solvent phase. 
     In some embodiments: 
     the feed liquid includes saline water; 
     the solvent phase includes water; and 
     the solute includes inorganic salts dissolved in water. 
     In some embodiments, the method includes treating the extract including the solvent liquid enriched in the solvent phase to produce the solvent phase and the solvent liquid depleted in the solvent phase. 
     In a general aspect, the present disclosure provides a method of extracting an extractable component from a feed liquid including the extractable component, the method including: 
     contacting the feed liquid with a solvent liquid at a first temperature using a porous membrane that is configured to maintain a contact between the feed liquid and the solvent liquid for an amount of time sufficient to allow for a dissolution of the extractable component into the solvent liquid at the first temperature; and 
     producing a raffinate containing the feed liquid depleted in the extractable component and an extract including the solvent liquid enriched in the extractable component, 
     wherein solubility of the extractable component in the solvent liquid at the first temperature is greater than solubility of the extractable component in the solvent liquid at a second temperature. 
     In some embodiments, the method also includes bringing the extract containing the solvent liquid enriched in the extractable component to the second temperature to produce the extractable component and the solvent liquid depleted in the extractable component. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. Methods and materials are described herein for use in the present disclosure; other, suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. Other features and advantages of the present disclosure will be apparent from the following detailed description and figures, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram schematically showing an extraction process  100  for extracting an extractable component A from a feed liquid by a solvent liquid. 
         FIG. 2A  is an SEM image of a porous hollow fiber membrane. 
         FIG. 2B  is a schematic showing of a contact area at the mouth of the pores of a porous membrane between two immiscible liquids. 
         FIG. 3  is a flow chart for an exemplary process  300  for extracting a solvent phase from a feed liquid by a solvent liquid. 
         FIG. 4  is a flow chart for an exemplary process  400  for extracting water from an aqueous feed liquid by a solvent liquid. 
         FIG. 5  is a schematic representation of a temperature-swing solvent extraction process. 
         FIG. 6  is a flow chart for an exemplary process  600  for extracting an extractable component from a feed liquid by a solvent liquid using a temperature-swing solvent extraction technique. 
         FIG. 7  is a schematic representation of an exemplary membrane-assisted temperature-swing solvent extraction process  700 . 
     
    
    
     DETAILED DESCRIPTION 
     In one general aspect, the present disclosure provides a method for extracting water from a feed liquid into a solvent liquid using a porous membrane to create a contact between the feed liquid and the solvent liquid during the extraction. The present disclosure is based, at least in part, on a realization that the porous membrane allows for precise control of a contact area between the feed liquid and the solvent liquid. Generally, using the porous membrane according to the methods of the present disclosure provides much larger contact area between the feed liquid and the solvent liquid per unit volume compared to the conventional extraction processes where the feed liquid and the solvent liquid are admixed (or contacted) without any membrane. Increasing the contact area between the liquids, in turn, results in accelerated mass transfer between the liquids and an increase in overall efficiency of the extraction process. Furthermore, the use of the porous membrane completely eliminates a time-consuming conventional step of separating the extract phase and the raffinate phase by gravity, which reduces the process time and further contributes to the overall efficiency of the extraction process within the present claims. 
       FIG. 1  shows a typical extraction process  100 . Referring to  FIG. 1 , a stream  108  of a feed liquid  102  containing an extractable component A is contacted with a stream  110  of a solvent liquid in an extraction system  106 . In a laboratory setting, the extraction system  106  can be a separatory funnel shaken by hand. In an industrial setting, the extraction system  106  can be a mixing tank equipped with a mechanical stirrer or an agitator to ensure complete mixing of the feed liquid  102  and the solvent liquid  104  in the extraction system  106 . 
     When the feed liquid and the solvent liquid are physically contacted in the extraction system  106 , for example, by vigorously mixing the two liquids, the extractable component A transfers from the feed liquid to the solvent liquid, due to higher solubility of the component A in the solvent liquid as compared to the feed liquid. As a result, a stream  112  is produced of an extract  116  containing the solvent liquid enriched in the component A, and a stream  114  is produced of a raffinate  118  containing the feed liquid depleted in component A. The solvent liquid is “enriched” in component A if the amount of component A in the extract  116  is greater than the amount of component A in the solvent liquid  104 . In one example, the solvent liquid  104  is free of component A, while the extract  116  is saturated with the component A (having the maximum possible amount of component A that can dissolve in the solvent liquid at a given temperature). In a similar manner, the feed liquid is “depleted” in component A if the amount of component A in the raffinate  118  is less than the amount of component A in the feed liquid  102 . In one example, an amount of component A in the extract  116  is substantially equal to the difference between an amount of component A in the feed liquid  102  and an amount of component A in the raffinate  118 . 
     Referring to the conventional process  100 , the feed liquid  102  and the solvent liquid  104  are immiscible. In one example, the feed liquid  102  is hydrophilic and the solvent liquid  104  is hydrophobic. In another example, the feed liquid  102  is hydrophobic and the solvent liquid  104  is hydrophilic. As used herein, two liquids are “immiscible” if they are incapable of being mixed to form a homogenous liquid. For example, a solvent liquid  104  is water-immiscible if the solvent liquid  104  is incapable of being mixed with water to form a homogenous liquid. However, during the extraction process in the extraction system  106 , the droplets of the two immiscible liquids  102  and  104  are in physical contact to allow the mass transfer of the extractable component A from the feed liquid  102  to the solvent liquid  104 . 
     Extraction methods of the present disclosure, which generally include using a porous membrane to create a contact between a feed liquid and a solvent liquid, may be described with reference to extraction system  106 , feed liquid  102 , solvent liquid  104 , extract  116 , raffinate  118 , and extractable component A as described above for the conventional extraction process  100 . Certain embodiments of the porous membrane, the extraction system, the solvent liquid, the feed liquid, the extract, the raffinate, the extractable component, as well as various other parameters of the extraction processes of the present disclosure, are described below. 
     In some embodiments, a feed liquid  102  is a solution which contains a solvent phase and a solute dissolved in the solvent phase. In one example, the extractable component A is the solvent phase of the feed liquid  102 . In another example, the extractable component A is the solute dissolved in the solvent phase of the feed liquid  102 . In this example, prior to dissolution in the solvent phase of the feed liquid  102 , the extractable component may be a solid (e.g., sodium chloride salt) or a liquid (e.g., water or an aqueous solution). 
     In some embodiments, an extractable component A in the feed liquid  102  is water. That is, the feed liquid  102  is an aqueous liquid. In one example, the aqueous feed liquid  102  is a solution where water is a solute dissolved in an organic solvent phase. Suitable examples of such aqueous feed liquids include moist motor oil containing, e.g., from about 1 wt. % to about 5 wt. % of water, and a moist kerosene containing, e.g., from about 1 wt. % to about 5 wt. % of water. 
     In some embodiments, the aqueous feed liquid  102  is an aqueous solution, in which the solvent phase contains at least about 50 wt. % of water (e.g., at least about 60 wt. %, at least about 70 wt. %, at least about 80 wt. %, or at least about 90 wt. % of water in the solvent phase of the aqueous solution). In some embodiments, the feed liquid  102  is an aqueous solution in which water is the only solvent. In one example, the solute in the aqueous solution  102  can be at least one organic compound. Suitable examples of such organic compounds include aromatic petrochemicals such as benzene, naphthalene, toluene, and xylene. In some embodiments, the feed liquid  102  is an aqueous solution containing from about 0.1 wt. % to about 1 wt. % of light naphtha. In other embodiments, the feed liquid  102  is an aqueous solution containing a highly polar and water-soluble organic compound. One example of such embodiments is a feed liquid  102  which is an aqueous solution containing from about 1 wt. % to about 5 wt. % of an organic acid, such as benzoic acid, glutaric acid, succinic acid, or malonic acid. Another example of such embodiments is a feed liquid  102  which is an aqueous solution containing from about 5 wt. % to about 20 wt. % of a sugar such as a glucose. 
     In some embodiments, the feed liquid  102  is an aqueous solution containing at least one inorganic compound dissolved in the aqueous solvent. Suitable examples of such inorganic compounds include an acid, an oxide, a hydroxide, and a salt. In one example of such embodiments, the feed liquid  102  is an aqueous solution containing at least one inorganic salt. Suitable examples of such inorganic salts include sodium chloride, potassium chloride, magnesium chloride, sodium bromide, sodium fluoride, sodium iodide, sodium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, and calcium phosphate. In some embodiments, the feed liquid  102  is an aqueous solution which is a saline water having salinity from about 0.5 wt. % to about 5 wt. %, such as about 1 wt. %, about 2 wt. %, about 3.5 wt. %, or about 4 wt. %. As used herein, the term “salinity” refers to wt. % of inorganic salts dissolved in water to form the aqueous solution. Typically, from about 50 wt. % to about 99 wt. % of all inorganic salts dissolved in the saline water is sodium chloride (NaCl). In some embodiments, about 85 wt. % of all salts in saline water is sodium chloride, and the remaining 15 wt. % is a combination of potassium chloride, magnesium sulfate, magnesium chloride, and other inorganic salts. In some embodiments, the feed liquid  102  is a saline water selected from ocean water, seawater, salt-lake water, salt marsh water, brackish water, and briny water. In these embodiments, the saline water may also contain proteins, microorganisms, and other organic materials commonly found in naturally occurring salt-water. In some embodiments, a pH of the feed liquid is from about 7 to about 9, or from about 7.5 to about 8.4. In some embodiments, density of the feed liquid is from about 1 g/mL to about 1.3 g/mL, or from about 1 g/mL to about 1.1 g/mL. 
     In some embodiments, the feed liquid  102  and the solvent liquid  104  are contacted in the extraction system  106  using a porous membrane. Such a porous membrane may be configured and/or dimensioned to create and/or maintain a contact between the feed liquid  102  and the solvent liquid  104 . The membrane is porous in that it contains open pores, or flow channels, that connect two surfaces of the membrane. An example of a porous membrane that can be used in the extraction system  106  is shown in  FIG. 2A . Referring to  FIG. 2A , a porous membrane  200  in the form of a hollow fiber contains a lumen side (or a lumen surface)  202  and a shell side (or a shell surface)  204 , and a plurality of open pores, such as the pore  206 , between the surfaces  202  and  204  of the membrane  200 . As shown in  FIG. 2B , surface  202  of the membrane  200  may be contacted with a liquid  208 , while surface  204  may be contacted with a liquid  210 . The liquid  208  may then flow into the pores of the membrane  200 , such as the pore  206 , to create a contact area at the membrane surface  204  between the liquid  208  and the liquid  210 . In one embodiment, the liquid  208  is a feed liquid  102  (referring to  FIG. 1 ), and the liquid  210  is a solvent liquid  104  (referring again to  FIG. 1 ). In another embodiment, the liquid  208  is a solvent liquid  104  (referring to  FIG. 1 ), and the liquid  210  is a feed liquid  102  (referring again to  FIG. 1 ). Physical contact between the solvent liquid  104  and the feed liquid  102  at the membrane surface  204  allows for mass transfer of the extractable component A from the feed liquid  102  to the solvent liquid  104 . 
     In some embodiments, the membrane is prepared from a material to which either the solvent liquid or the feed liquid has an affinity. As used herein, a liquid has “affinity” (or is “affine”) to the membrane material when the liquid can provide a high degree of wetting of the surface of the membrane material. That is, the affine liquid can provide a contact angle with the surface between 0° and 90°, such that upon contact with the surface, the liquid can spread over a large area of the surface due to strong solid-liquid interactions. Without being bound by any theory, it is believed that a hydrophilic liquid has a strong affinity to a surface of a hydrophilic membrane material, while a hydrophobic liquid has a strong affinity to a surface of a hydrophobic membrane material. In some embodiments, the liquid having affinity for the membrane material (a feed liquid or a solvent liquid) contains a wetting agent. Examples of such wetting agents include surfactants, such as sodium lauryl sulfate, ethyl cellulose, polysorbate, or polymethylmethacrylate. 
     In one example of the present disclosure, the membrane material is hydrophobic, the solvent liquid  104  is hydrophobic, and the feed liquid  102  is hydrophilic and immiscible with the solvent liquid  104 . In this example, referring to  FIG. 2B , liquid  208  is the hydrophobic solvent liquid  104  that flows into the pores of the membrane  200 , such as the pore  206 , due to its physical affinity to the hydrophobic material of the membrane  200  and its concomitant ability to wet the inner surfaces of the pores. The hydrophilic feed liquid  102 , on the other hand, is prevented from wetting the membrane pores due to lack of affinity to the hydrophobic membrane material and weak solid-liquid interactions. 
     In another example of the present disclosure, the membrane material is hydrophilic, the feed liquid  102  is hydrophilic, and the solvent liquid  104  is hydrophobic and immiscible with the hydrophilic feed liquid  102 . In this example, referring to  FIG. 2B , liquid  208  is the hydrophilic feed liquid  102  that flows into the pores of the membrane  200 , such as the pore  206 , due to its physical affinity to the hydrophilic material of the membrane  200  and its concomitant ability to wet the inner surfaces of the pores. The hydrophobic solvent liquid, on the other hand, is prevented from wetting the membrane pores due to lack of affinity to the hydrophilic membrane material and weak solid-liquid interactions. 
     In yet another example of the present disclosure, the membrane material is hydrophilic, the solvent liquid  104  is hydrophilic, and the feed liquid  102  is hydrophobic and immiscible with the hydrophilic solvent liquid  104 . In yet another example, the membrane is hydrophobic, the feed liquid is hydrophobic, and the solvent liquid is hydrophilic and immiscible with the feed liquid. 
     In some embodiments, the porous membrane is prepared from a hydrophobic material. In some embodiments, the processes of the present disclosure include preparing the porous membrane from a hydrophobic material. Examples of hydrophobic materials include hydrophobic polymers, such as fluoropolymers. In some embodiments, the hydrophobic membrane material contains polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polymethylpentene, poly(vinyltrimethylsilane), hexafluoropropylene, polysulfone (PSU), polyethersulfone (PES), or polyphenylene sulfone (PPSU), including mixtures or copolymers thereof, such as poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP). The hydrophobic membrane material may also contain pore former additives, such as polyvinylpyrrolidone (PVP), lithium chloride (LiCl), glycerol, or polyethylene glycol (PEG). In some embodiments, hydrophobicity of the surface of the membrane material may be increased by including coating and nanoparticles, such as TiO 2 , SiO 2 , or carbon nanotubes, into the membrane material. In some embodiments, the hydrophobic membrane in the extraction system  106  can be any one the hydrophobic membranes useful for water desalination by membrane distillation (for example, direct contact membrane distillation or air gap membrane distillation). 
     In some embodiments, the membrane is prepared from a hydrophilic material. Suitable examples of hydrophilic materials include hydrophilic polymers, such as polymers containing numerous hydroxyl groups. In some embodiments, the hydrophilic membrane material includes cellulose, cellulose diacetate, cellulose triacetate, polyethylene glycol (PEG), polyetherimide (PEI), or any mixtures or copolymers thereof. Other suitable examples of hydrophilic membrane materials include inorganic materials, such as ceramics, oxides, glass, carbon, zeolites, or Al 2 O 3 . The hydrophobic membrane material may also contain additives, such as binders, dispersants, pore formers, plasticizers, or any mixture of the foregoing. In some embodiments, the hydrophilic membrane in the extraction system  106  can be any one the hydrophilic membranes useful in membrane contactor applications or catalytic processing. 
     In some embodiments, a porous membrane has porosity in a range from about 10% to about 85%. As used herein, the term “porosity” refers to a ratio of the combined volume of all pores in a material to the total volume of the material (including the pores). Membrane porosity may be determined, for example, using a gravimetric method. In one example, porosity can be determined by measuring weight change of the material before wetting (dry state) and after wetting (wet state) using a wetting liquid for which the density is already known. Based on the measured weight change, the volume of pores which is filled by wetting liquid can be calculated. In some embodiments, porosity of a membrane of the present disclosure is from about 10% to about 75%, from about 10% to about 65%, or from about 10% to about 50%. In some embodiments, a density of the membrane is from about 0.1 g/cm 3  to about 5 g/cm 3 , for example, from about 0.8 g/cm 3  to about 2.3 g/cm 3 . 
     In some embodiments, mean pore size of the pores of a porous membrane of the present disclosure is from about 10 nm to about 100 μm, from about 50 to about 500 nm, or from about 100 nm to about 400 nm. In some embodiments, the membrane is mesoporous (having pores with diameters between about 2 nm and about 50 nm) or macroporous (having pores with diameters larger than about 50 nm) according to IUPAC nomenclature. 
     In some embodiments, liquid entry pressure of the porous membrane of the present disclosure is from about 1 bar to about 20 bar, from about 1 bar to about 4 bar, or from about 1.1 bar to about 3.9 bar. As used here, the term “liquid entry pressure,” or “LEP,” refers to a minimum pressure that is required for a liquid to penetrate and flow into the largest pore on the membrane surface. In some embodiments, LEP is determined for a liquid that lacks affinity to the membrane material. In one example of such embodiments, LEP may be determined for a hydrophobic membrane and a hydrophilic liquid. In another example of such embodiments, LEP may be determined for a hydrophilic membrane and a hydrophobic liquid. Generally, LEP can be determined using the following equation: 
     
       
         
           
             
               Δ 
               ⁢ 
               
                   
               
               ⁢ 
               P 
             
             = 
             
               
                 4 
                 ⁢ 
                 σ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 cos 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 θ 
               
               
                 d 
                 p 
               
             
           
         
       
     
     In this equation, σ is surface tension of the liquid (J/m 2 ), θ is a contact angle of the liquid on the membrane surface (degree), and d P  is the maximum pore size of the membrane (m). 
     In some embodiments, a porous membrane in the extraction system  106  may be in a planar form or a tubular form. Example of the planar form include a flat sheet membrane, and the example of tubular form includes a hollow fiber membrane. Flat-sheet membrane can be used in a spiral-wound membrane module, while a hollow fiber membrane can be used in a hollow fiber membrane module. An example of a hollow fiber membrane is shown in  FIG. 2A . As seen in  FIG. 2A , a hollow fiber membrane has in outside diameter (or shell diameter) d2 ( 214 ), and in inside diameter (or lumen diameter) d1 ( 212 ). In one example, a ratio of an outside diameter to an inside diameter of the follow fiber membrane can be from about 1.1 to about 2.5, or from about 1.1 to about 1.8. In this example, outside diameter of the hollow fiber may be from about 0.3 mm to about 4 mm, from about 0.3 mm to about 1 mm, or from about 0.3 mm to about 0.5 mm. 
     The porous membrane of the present disclosure may be prepared by any technique or process known in the industry for making membrane materials. Suitable examples of processes useful in making porous membranes of the present disclosure include phase inversion methods, such as diffusion induced phase separation process (DIPS), non-solvent induced phase separation process (NIPS), or thermally (or temperature) induced phase separation process (TIPS). The porous membranes may be prepared with any desired degree of flexibility, elasticity, toughness, rigidity, and mechanical strength. A membrane material may be judiciously chosen to ensure the porous membrane is stable and at any operational temperature. A skilled chemical engineer would be able to select and optimize the process parameters to obtain a porous membrane with the desired properties, including mechanical properties and operational properties, such as hydrophobicity and hydrophilicity, porosity, pore size, pore size distribution, and LEP. 
     In some embodiments, using a porous membrane of the present disclosure in the extraction system  106  leads to a mass transfer coefficient for extractable component A that is from about 3 to about 9 times higher when compared to a conventional direct contact system  106 . Without being bound by a theory, it is believed that the mass transfer coefficient is much higher in the instant process because the contact area between the feed liquid  102  and the solvent liquid  104  is much greater when compared to direct contact, such as shaking or otherwise vigorously mixing. In addition, by varying the process parameters (such as using membranes with different pore sizes and porosity characteristics), contact area between the feed liquid  102  and the solvent liquid  104  during the extraction process can be precisely controlled, which allows for quick process optimization and compact membrane module assembly. A mass transfer coefficient for the membrane extraction process of the present disclosure can be determined as is customary in the field. A mass transfer coefficient is usually determined using knowledge about membrane structure (membrane material, pore sizes, pore size distribution, porosity), solubility characteristics of the extractable component A in the feed liquid  102  and the solvent liquid  104 , as well as the physical properties of the feed liquid  102  and the solvent liquid  104 . Furthermore, using a porous membrane of the present disclosure eliminates a conventional step of separation the raffinate  118  from the extract  116  by gravity. 
     In some embodiments, the present disclosure provides a method of extracting a solvent phase from a feed liquid containing a solvent phase and a solute dissolved in the solvent phase.  FIG. 3  illustrates such a method  300 . Referring to  FIG. 3 , the method  300  includes a step  302  of contacting the feed liquid with a solvent liquid using a porous membrane that is configured and/or dimensioned to create and/or maintain a contact between the feed liquid and the solvent liquid for an amount of time sufficient to allow for a dissolution (or a mass transfer) of the solvent phase into the solvent liquid. Any one of the porous membranes described in this application can be successfully used in this method. A porous membrane may be selected by a skilled chemical engineer based on hydrophobicity, hydrophilicity, contact angle, density, and other operational characteristics of the feed liquid and the solvent liquid. An amount of time for contacting the feed liquid and the solvent liquid may range from about 1 second to about 1 hour. In some embodiments, the porous membrane is configured to create and/or maintain a contact between the feed liquid and the solvent liquid at or near a surface of the porous membrane, such at the mouth of the open pores along the surface. An example of a membrane surface where the liquids can be contacted is surface  204  in  FIG. 2B . In one example, the solvent liquid useful in step  302  is immiscible with the feed liquid, and the solvent phase of the feed liquid is soluble in the solvent liquid. Solubility of the feed liquid&#39;s solvent phase in the solvent liquid used in step  302  may be from about 5 g/L to about 500 g/L. In some embodiments, the solute dissolved in the solvent phase of the feed liquid is substantially insoluble in the solvent liquid used in the extraction process in step  302 . The method  300  may also include a step  304  of producing a raffinate containing the feed liquid depleted in the solvent phase (enriched in the solute) and an extract containing the solvent liquid enriched in the solvent phase. In one example of step  304 , the solvent liquid in the extract may be saturated with the feed liquid&#39;s solvent phase, that is, the concentration of the feed liquid&#39;s solvent phase in the solvent liquid has reached its maximum at a given temperature. The method  300  may also include a step  306  of treating the extract obtained in step  304  to produce (or separate) the feed liquid&#39;s solvent phase and the solvent liquid depleted in the solvent phase. When the boiling point of the feed liquid&#39;s solvent phase is greater than the boiling point of the solvent liquid, for example, by about 50° C., about 70° C., or about 100° C., step  306  of the method  300  may include evaporating the solvent liquid, e.g., using a rotovap, leaving in the bottoms the extracted feed liquid&#39;s solvent phase. When solubility of the feed liquid&#39;s solvent phase in the solvent liquid is temperature-dependent, treating step  306  of the method  300  may also include changing (increasing or decreasing) a temperature of the extract, thereby reducing solubility of the solvent phase in the solvent liquid and inducing separation of the extracted solvent phase and the solvent liquid. The extracted solvent phase and the solvent liquid may be further physically separated by gravity using, for example, a separatory funnel or a similar industrial equipment. 
     In some embodiments, the present disclosure provides a method of extracting water form a feed liquid containing water.  FIG. 4  illustrates such a method  400 . Referring to  FIG. 4 , the method  400  includes a step  402  of contacting the feed liquid containing water with a solvent liquid using a porous membrane that is configured and/or dimensioned to create and/or maintain a contact between the feed liquid and the solvent liquid for an amount of time sufficient to allow for a dissolution of water into the solvent liquid. In some embodiments of the process  400 , the feed liquid containing water in step  402  is any one of the aqueous feed liquids or aqueous solutions described in the present disclosure for the feed liquid  102  (referring to  FIG. 1 ). In some embodiments, the feed liquid containing water in step  402  is a saline water containing water as a solvent phase and inorganic salts dissolved in water as a solute. Examples of such embodiments include seawater, brackish water, or salt-lake water, having salinity from about 1 wt. % to about 4 wt. %. The method  400  may also include a step  404  of producing a raffinate containing the feed liquid depleted in water and an extract containing the solvent liquid enriched in water. When saline water is used as the feed liquid in step  402 , the raffinate obtained in step  404  may be a saturated brine, containing from about 10 wt. % to about of 35 wt. % of inorganic salts dissolved in feed liquid, such as NaCl and other inorganic salts. In some embodiments of step  402 , the feed liquid containing water is hydrophilic, the porous membrane is hydrophobic, and the solvent liquid is hydrophobic. 
     A solvent liquid useful in step  402  may be any solvent or a mixture of solvents which is immiscible with an aqueous feed liquid and in which water is soluble. In some embodiments, solubility of water in the solvent liquid useful in step  402  is in a range from about 2 wt. % to about 65 wt. %. That is, a saturated solution of water in the solvent liquid may contain from 2 wt. % to about 65 wt. % of water based on the amount of solvent liquid prior to forming the solution. In some embodiments, a saturated solution of water in the solvent liquid is water-immiscible or otherwise immiscible with an aqueous solution. A solvent liquid useful in step  402  may contain a mixture of a water-miscible organic solvent (that can be mixed with water in any proportion) and a water-immiscible organic solvent (which cannot dissolve any substantial amount of water), such that the solvent liquid is immiscible with an aqueous feed liquid but retains the ability to dissolve water. Examples of water-miscible organic solvents include acetone, methylethylketone, tetrahydrofuran, dioxolane, monoglyme, methylal and acetonitrile. Examples of water-immiscible organic solvents include ethyl acetate, butyl acetate, toluene, and xylene. A solvent liquid useful in step  402  may contain from about 10 wt. % to about 30 wt. % of a water-miscible organic solvent and from about 70 wt. % to about 90 wt. % of a water-immiscible organic solvent. In some embodiments, the solvent liquid useful in step  402  contains a solvent, the saturated solution of water in which is immiscible with water or another aqueous fluid. Examples of such solvents include dioxane, trioxane, trioxepane, tetraoxopane, and any other solvents described in U.S. Pat. No. 3,415,744, which is incorporated herein by reference in its entirety. In addition to such solvent, the solvent liquid may also contain a water-miscible or a water-immiscible organic solvent, or a mixture thereof. 
     In some embodiments, solubility of water in a solvent within the solvent liquid useful in step  402  is temperature-dependent. That is, solubility of water in the solvent at one temperature is different from solubility of water in the same solvent at a different temperature. An exemplary process  500  for extracting water from saline feed water using a solvent having temperature-dependent water solubility is shown in  FIG. 5 . Referring to  FIG. 5 , in step  502  a hydrophobic solvent  504  is admixed with hydrophilic saline water  506 . In this example, hydrophobic solvent  504  has a density less than the density of saline water  506 , and because the two liquids are immiscible, the liquid layers are separated by gravity with the layer of solvent  504  above the layer of saline water  506 . In the next step  508 , the hydrophobic solvent  504  and the saline water  506  are vigorously stirred using a mechanical agitator  510  to produce a homogenous mixture  512 . The stirring in  508  is carried out at a first temperature, when solubility of water in the solvent  504  is generally high (greater than solubility of water in solvent  504  at a second temperature). During the stirring in  508 , solvent  504  is in direct contact with the saline water  506  within the mixture  512 . During the direct contact, the solvent  504  selectively extracts water (a solvent phase) from the saline water  506  while leaving solutes (inorganic salts such as NaCl) in the raffinate. In  514 , when the stirring is stopped, the immiscible phases are separated gravitationally to produce a raffinate brine  518  and an extract  516 . In step  520 , the extract phase  516  can be further physically separated from brine  518  using, for example, a separatory funnel, to obtain the extract  522  that contains solvent  504  that is saturated with water at the first temperature. Further, extract  522  can be treated to a second temperature which is different from the first temperature (second temperature is either higher or lower than the first temperature). Due to decreased solubility of water in solvent  504  at the second temperature, in step  524 , the extract  522  yields two immiscible phases, fresh water  528  and solvent  526 , which are separated by gravity. In  524 , the solvent phase  526  is saturated with water at the second temperature, and the water content in  526  is less than the water content in  516  and  522 . Fresh water  528  can be further separated from solvent  526  using, for example, a separatory funnel, for further use. At the same time, solvent  526  can be brought to the first temperature and recycled in step  502  of the process  500  as solvent  504 , which may be replenished as necessary. In the process  500 , the first temperature and the second temperature are generally in a range from about 20° C. to about 80° C., or from about 20° C. to about 60° C., depending on the hydrophobic solvent  504  used in the process. If the first temperature is greater than the second temperature, extract  522  requires cooling in step  520 . If the second temperature is greater than the first temperature, extract  522  requires heating in step  520 . 
     Conventional process  500 , however, suffers from serious drawbacks. For example, immiscible phases  516  and  518  at the raffinate separation step  514  may take a long time to separate, thereby decreasing overall efficiency of the extraction process. In some cases, the raffinate separation step takes up a third of the overall process time. Methods of the present disclosure, such as method  400  shown in  FIG. 4 , significantly enhance performance of the conventional processes such as process  500  by using a porous membrane (for example, a hydrophobic membrane) as a contactor between saline water  506  and hydrophobic solvent  504  in the contacting step  508 . Using the porous membrane at the contact step  508  completely eliminates the raffinate separation step, as the extract  522  and raffinate  518  are directly obtained from the contacting step  508 , thereby decreasing process time and increasing overall efficiency. Hence, a hydrophobic solvent  504  having temperature-dependent water solubility may be used as a solvent liquid in the method  400  shown in  FIG. 4 . 
     In some embodiments, the present disclosure also provides a method for extracting an extractable component from a feed liquid.  FIG. 6  illustrates such a method  600 . Referring to  FIG. 6 , the method  600  includes a step  602  of contacting the feed liquid containing an extractable component with a solvent liquid at a first temperature using a porous membrane that is configured and/or dimensioned to create and/or maintain a contact between the feed liquid and the solvent liquid for an amount of time sufficient to allow for a dissolution of the extractable component into the solvent liquid at the first temperature. In some embodiments, solubility of the extractable component in the solvent liquid at the first temperature is greater than solubility of the extractable component in the solvent liquid at a second temperature. In some embodiments, the first temperature is greater than the second temperature. In these embodiments, the first temperature is in a range from about 50° C. to about 90° C., and the second temperature is in a range from about 10° C. to about 40° C. In other embodiments, the second temperature is greater than the first temperature. In these embodiments, the first temperature is in a range from about 30° C. to about 55° C., and the second temperature is in a range from about 60° C. to about 100° C. The porous membrane useful in step  602  is any of the porous membranes described earlier. In some embodiments, the process  600  also includes a step  604  of producing a raffinate containing the feed liquid depleted in the extractable component and an extract containing the solvent liquid enriched in the extractable component. In some embodiments, the process  600  also includes a step  606  for bringing the extract containing the solvent liquid enriched in the extractable component to the second temperature to produce the extractable component and the solvent liquid depleted in the extractable component. 
     In some embodiments of the process  600 , the extractable component is water and the feed liquid is any of the aqueous liquids or aqueous solutions described herein. In some aspects of these embodiments, the feed liquid is saline water and the raffinate produced in step  604  is brine. Saline waters and brines are described herein. 
     In some embodiments, solvent liquid in step  602  includes a solvent that can dissolve water in a temperature-dependent manner while being immiscible with an aqueous feed liquid (such as saline water). This solvent possesses the ability to dissolve water while leaving in raffinate various water-soluble substances, such as sodium chloride. Suitable examples of such a solvent include compounds having hydrophilic moieties in a mainly hydrophobic chemical structure. 
     One example of such compounds having hydrophilic moieties in a mainly hydrophobic chemical structure is the alkylamines. These compounds have a hydrophilic nitrogen atom with a lone pair of electrons that can form hydrogen bonds with water molecules, while also having hydrophobic alkyl groups. Alkyl groups adjacent to the nitrogen atom further increase the dipole moment of the alkylamine molecules by the inductive effect, thus increasing affinity of the nitrogen atom for water molecules. Solubility of water in alkylamine solvents may be temperature-dependent. Without being bound by a theory, it is believed that at a higher temperature, free rotation of the alkyl groups of the alkylamines increases. Hence, the nitrogen atom is more sterically hindered, and fewer water molecules can be H-bonded to the N atom, resulting in a decrease in solubility of water in the alkylamine solvent. In contrast, at a lower temperature, free rotation of alkyl groups is slower, allowing for more space for water molecules to H-bond with the N atom. Hence, at a lower temperature, solubility of water in alkylamine solvent is increased. Accordingly, in some embodiments of step  602 , when solvent liquid contains an alkylamine solvent, the second temperature is greater than the first temperature (the process  600  requires cooling in extraction step  602  and heating in the separation step  606 ). Examples of alkylamine solvents include diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), N,N,-dimethylcyclohexylamine (DMCHA), N-methylbutyl amine, diethylmethylamine, or N-ethylpropylamine, or any combination thereof. 
     In some embodiments of step  602 , the solvent liquid includes N-methylbutyl amine, the first temperature is from about 40° C. to about 45° C., the second temperature is from about 85° C. to about 95° C., solubility of water in the solvent liquid at the first temperature is from about 60 wt. % to about 65 wt. %, while solubility of water in the solvent liquid at the second temperature is from about 30 wt. % to about 35 wt. %. 
     In some embodiments of step  602 , the solvent liquid includes diethylmethylamine, the first temperature is from about 50° C. to about 55° C., the second temperature is from about 60° C. to about 65° C., solubility of water in the solvent liquid at the first temperature is from about 35 wt. % to about 40 wt. %, while solubility of water in the solvent liquid at the second temperature is from about 20 wt. % to about 30 wt. % (e.g., about 25 wt. %). 
     In some embodiments of step  602 , the solvent liquid includes N-ethylpropylamine, the first temperature is from about 45° C. to about 55° C., the second temperature is from about 75° C. to about 85° C., solubility of water in the solvent liquid at the first temperature is from about 45 wt. % to about 55 wt. %, while solubility of water in the solvent liquid at the second temperature is from about 20 wt. % to about 30 wt. % (e.g., about 25 wt. %). 
     Another example of compounds having hydrophilic moieties in a mainly hydrophobic chemical structure is the edible oils and medium chain fatty acids. These compounds dissolve water due to the presence of a carboxylic acid group (COOH) at the aliphatic chain end. Highly polar C═O and OH groups in these compounds facilitate formation of hydrogen bonds with water molecules. While the chain ends are hydrophilic, the aliphatic chain itself is hydrophobic; hence, the fatty acid solvent that is saturated with water is immiscible with water or other aqueous solutions and feed liquids. Solubility of water in these fatty acid solvents increases with temperature. Accordingly, in some embodiments of step  602 , when solvent liquid contains a fatty acid solvent, the first temperature is greater than the second temperature (the process  600  requires heating in the extraction step  602  and cooling in the separation step  606 ). Examples of fatty acid solvents include decanoic acid and octanoic acid, or any combination thereof. 
     In some embodiments of step  602 , the solvent liquid includes decanoic acid, the first temperature is from about 75° C. to about 85° C., the second temperature is from about 30° C. to about 40° C., solubility of water in the solvent liquid at the first temperature is from about 5 wt. % to about 6 wt. %, while solubility of water in the solvent liquid at the second temperature is from about 3 wt. % to about 4 wt. % (e.g., about 3.8 wt. %). 
     In some embodiments of step  602 , the solvent liquid includes octanoic acid, the first temperature is from about 55° C. to about 65° C., the second temperature is from about 20° C. to about 30° C., solubility of water in the solvent liquid at the first temperature is from about 5 wt. % to about 5.5 wt. %, while solubility of water in the solvent liquid at the second temperature is from about 2 wt. % to about 3 wt. %. 
     In some embodiments, solvent liquid in step  602  includes an additional solvent, such as a water-miscible or a water-immiscible solvent, or a mixture thereof. Examples of water-miscible and water-immiscible solvents that could be added to the solvent liquid in  602  are described herein. 
     An exemplary process  700  for extracting a pure water extractable component from a saline water feed liquid using a solvent liquid containing decanoic acid is illustrated in  FIG. 7 . In the process  700 , saline feed water  702  is added to the feed water mixing tank  704 . The mixing tank  704  is equipped with a cooling/heating element  706 , which may heat the saline feed water to a first temperature from about 75° C. to about 85° C. To heat the feed water,  706  may contain hot water of steam. The heated saline feed water is then pumped to a membrane module  710  using a feed water circulation pump  708 . A rate of saline water flow may be measured using a flowmeter  712 . Temperature and pressure of the feed liquid can be measured using a gauge  714 . At the same time, solvent liquid containing decanoic acid may be placed in a solvent tank  716  that is equipped with a heating/cooling element  718  which may heat the decanoic acid solvent to a first temperature from about 75° C. to about 85° C. The heated decanoic acid solvent is then pumped to a membrane module  710  using a solvent circulation pump  718 . A rate of decanoic acid solvent flow can be measured using a flowmeter  722 . Temperature and pressure of the solvent flow may be measured using a gauge  724 . The membrane module  710  can contain a hydrophobic porous membrane, such as any of the hydrophobic membranes described herein. An exemplary hydrophobic porous membrane in module  710  is a hollow fiber membrane prepared from polytetrafluoroethylene (PTFE). The membrane may have porosity from about 10% to about 85%, with pore sizes in the range from 10 nm to about 80 μm, such as from 50 nm to about 500 nm. The module  710  may contain a plurality of hollow fiber membranes. Ratio of shell diameter to lumen diameter for each hollow fiber may be from about 1.1 to about 2.5, with the shell diameter for each hollow fiber from about 300 μm to about 4 mm. In one example, ratio of shell diameter to lumen diameter for each of the hollow fiber membranes may be from about 1.1 to about 1.8, with the shell diameter of each hollow fiber from about 300 μm to about 500 μm. Referring to a cross-section  728  of an exemplary hollow fiber membrane  730  taken at a section  726  of the module  710 , the decanoic acid solvent flows into a lumen side  732  of the membrane  730 . Upon contact with the lumen surface  734 , due to its hydrophobic nature, decanoic acid wets the surface  734  of the hydrophobic membrane and flows into the pores and fills the pores of the membrane  730 , where it contacts saline feed water at the shell surface  736  of the membrane  730 . Because both the decanoic acid solvent and the saline feed water are heated at the first temperature of 80° C., during the contacting, pure water is extracted from the saline water feed liquid into the decanoic acid. The decanoic acid solvent and the saline water feed liquid may be contacted in the module  710  in a countercurrent mode or in a concurrent mode. In one example, the contact between the decanoic acid solvent and the saline water feed liquid is carried out during a countercurrent exchange. The liquids may be contacted for an amount of time that is sufficient to obtain an extract  738  that is a saturated solution of water in decanoic acid at the temperature of 80° C., containing about 5.9 wt. %. The sufficient amount of time may range from about 1 second to about 1 hour, and may be precisely controlled, for example, by varying length of the hollow fiber membrane  730  and/or the diameter of the module and/or the flow rates of the feed water and the decanoic acid solvent liquid by controlling feed water circulation pump  708  and/or solvent circulation pump  720 . Temperature and pressure of the extract  738  flowing from the membrane module  710  can be determined using a gauge  740 . The pressure of the extract  738  can be further regulated using an extract back pressure regulator  742 . The extract may be collected in a water-solvent separator  744 , which may be equipped with a heating/cooling element  746 . Using this element  746 , the extract may be brought to a second temperature from about 30° C. to about 35° C. To cool the extract  738  in the separator  744 , element  746  may contain a refrigerant, such as a freon. At the second temperature, solubility of water in decanoic acid decreases to about 3.8 wt. %. As a result, pure water  748  precipitates at the bottom of the separator  744 . The pure water  748  gravitationally settles at the bottom of the separator  744  because it is immiscible with the water-depleted decanoic acid at the second temperature, and because density of water is greater than density of decanoic acid. A decanoic acid solvent  752  containing only about 3.8 wt. % of water can be recycled in  750  to the solvent tank  716 . The solvent tank  716  may be replenished with fresh decanoic acid solvent as needed. At the same time, raffinate brine  754  flowing from the membrane module  710  can be collected or returned to feed water tank  704 , where it can be diluted with fresh saline water feed liquid. Temperature and pressure of the raffinate  754  flowing from the membrane module  710  can be determined using a gauge  756 . Pressure of the raffinate  754  can be further regulated using a raffinate back pressure regulator  758 . During the extraction process in the membrane module  710 , saline feed water pressure (determined at  714 ) remains higher than the solvent pressure (determined at  724 ) using, for example, back pressure regulators  742  and  758 . Furthermore, trans-membrane pressure (a difference between saline feed water pressure and solvent pressure) remains lower that the LEP for the hollow fiber membrane in the module  710 . Exemplary LEP of the hollow fiber membrane in module  710  is from about 1 bar to about 20 bar. 
     In some embodiments, pure water  748  is a potable water. Potable water may contain no more than 0.1 wt. % of salts such as sodium chloride. Generally, potable water is drinking water and is also useful for plumbing, including toilet flushes. In some embodiments, pure water  748  is a drinking water containing no more that about 0.05 wt. % of dissolved inorganic salts. In other embodiments, pure water  748  has salinity as high as 0.2 wt. % and is useful in agriculture, for example, for irrigation. This water is also useful for various industrial purposes, such as washing or cooling, as well as in various manufacturing processes where use of water is necessary. 
     Selected Definitions 
     Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (for example, 1%, 2%, 3%, and 4%) and the sub-ranges (for example, 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise. 
     In this disclosure, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed in this disclosure, that is not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. 
     The term “about” as used in this disclosure can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range. 
     The term “substantially” as used in this disclosure refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more. 
     As used in this disclosure, the term “fluid” refers to liquids, gels, slurries, including slurries with a substantial solids content, and critical and supercritical materials. 
     Other Embodiments 
     It is to be understood that while the present disclosure has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the present disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.