85 results about "Pervaporation" patented technology

A pervaporation composite membrane belongs to the technical field of membrane separation. The pervaporation composite membrane comprises a porous substrate, a middle membrane layer and a separation membrane layer which are sequentially stacked, the average pore size of the porous substrate is greater than or equal to 250nm; the average pore size and porosity of the middle film layer are smaller than those of the porous substrate, and the middle film layer has the organic matter affinity characteristic; the separation membrane layer has the hydrophobic characteristic and the organic matter selective permeation characteristic. The middle membrane layer is beneficial to improving the problems of seepage holes, difficulty in spreading, uncontrollable thickness of the separation membrane layer and the like in the solid-liquid interface preparation process, ensures the defect-free preparation of the separation membrane layer, and is beneficial to improving the permeability of the pervaporation composite membrane to organic matters.

The invention relates to the technical field of membrane separation materials, in particular to a mixed matrix membrane and a preparation method and application thereof. The mixed matrix membrane comprises: (1) a polymer functional membrane; (2) a base film for supporting the polymer functional film; a polymer in the polymer functional film comprises a polymer with a structure as shown in a formula (a), in the formula (a), R0 is an alkylene chain, R1 is a polysiloxane group, R2 is alkyl or hydrogen, and m is equal to 1-20. According to the present invention, the functional membrane prepared from the polymer having the structure (a) is used, and the structure of the polysiloxane is designed and optimized, such that the mixed matrix membrane has excellent organic solvent tolerance and organic solvent pervaporation separation property, and the interfacial compatibility between the polymer and the porous filler can be improved.

The invention belongs to the technical field of ethanol recovery, and relates to a preparation method of a tubular ceramic carrier-based C-ZIF-67 derived nano-porous carbon doped PDMS mixed matrix membrane and an application of the membrane in recovery of ethanol by pervaporation of a low-concentration ethanol aqueous solution. Comprising the following steps: synthesizing a ZIF-67 crystal, and carbonizing the ZIF-67 crystal to obtain C-ZIF-67 filler particles; the ZIF-67-derived nano-porous carbon particles are prepared through a high-temperature calcination method, the particles are fully carbonized at a certain calcination temperature, disappearance of characteristic groups after carbonization can reduce the influence of surface electrical properties of the particles, and the size shrinkage of the particles is reduced, so that the dispersity of the particles in a matrix membrane is improved; meanwhile, the MOF skeleton structure is still reserved after carbonization, the pore diameter is increased, the carbon material also has strong hydrophobicity, the hydrophobic large-pore-diameter separation pore channels are more beneficial to passing of ethanol molecules and promotion of the separation effect, the separation factor and the total flux are almost kept unchanged after long-time operation and use, and excellent performance is shown; good application prospects are realized.

The invention discloses a preparation method and application of an MFI zeolite membrane.The preparation method comprises the steps that an MFI zeolite nanosheet serves as a seed crystal, a uniformly-distributed and compact seed crystal layer is prepared on a carrier through a vacuum filtration method, namely, a nucleation center crystallized into a membrane is loaded on the surface of the carrier, and directional growth and membrane forming of the zeolite nanosheet can be effectively controlled; the highly b-oriented MFI zeolite membrane can be prepared within several hours, the prepared b-oriented MFI zeolite membrane shows a continuous and compact microstructure and almost has no defects, and compared with a traditional hydrothermal method, the method overcomes the defects that the reaction process is too long in time consumption, uneven in heating is prone to occurring, and the like. And therefore, the time required by crystal growth is greatly shortened. The prepared MFI zeolite membrane can be applied to pervaporation separation of xylene isomers, shows good size screening separation performance, and has important industrial application value.

The invention discloses a water purification process based on a pervaporation desalination technology, which comprises the following steps: firstly, raw water is guided to a raw water buffer tank, and water quality parameters are monitored through built-in conductivity, temperature and liquid level sensors; secondly, the circulation of raw water in the system is realized by utilizing a raw water circulating pump; then, the raw water is preheated by a shell pass of the pre-condenser and then is fed into a hot-end heat exchanger of the heating and condensing coupler to be heated; then, the heated raw water enters a pervaporation desalination membrane element to complete a pervaporation process, concentrated water returns to the raw water buffer tank to continue to circulate, and the raw water becomes steam under the action of a vacuum pump and enters a tube pass of a pre-condenser to be primarily condensed; then, the primarily condensed water vapor is further condensed by heating a cold end heat exchanger of the condensation coupler; finally, purified water formed by condensation is collected in a produced water storage tank; the process can effectively remove salt in water and improve the utilization rate of water resources.

The embodiment of the invention provides a tetrahydrofuran purification device and a tetrahydrofuran purification method, the tetrahydrofuran purification device comprises a normal pressure rectifying tower, pervaporation equipment and a pressurized rectifying tower, and the pervaporation equipment is connected between the normal pressure rectifying tower and the pressurized rectifying tower. Therefore, the use amount of the high-pressure steam can be reduced, the energy consumption of the high-pressure steam can be reduced, the operation cost can be reduced, the operation load of the pressurized rectifying tower can be reduced, and the load upper limit of the tetrahydrofuran purification device can be improved. In addition, the pervaporation equipment is positioned at the front end of the pressurized rectifying tower, so that the influence of the pressurized rectifying tower on the pervaporation equipment is reduced, the stability of the pervaporation equipment is improved, and the dehydration efficiency of the pervaporation equipment is improved.

The invention discloses a membrane separation experiment device and an experiment method thereof.The membrane separation experiment device comprises a raw material supply assembly, a heating assembly, a first separation assembly, a second separation assembly and a vacuum assembly, the raw material supply assembly comprises a raw material tank and an extraction part, and the raw material tank is connected with the extraction part; the heating assembly is connected with the extraction piece, and the heating assembly is used for heating the raw materials; the first separation assembly is connected with the heating assembly, and the first separation assembly is used for separating the mixed liquid; the second separation assembly is used for separating the mixed liquid before the first separation assembly works so as to determine optimal experiment parameters; the vacuum assembly is connected with the first separation assembly and the second separation assembly. According to the invention, continuous pervaporation separation of the mixed liquid can be realized, the problem of sealing failure or leakage of the first separation assembly caused by a high-temperature medium or fluid is avoided, and the risks of energy consumption waste and misoperation caused by unreasonable experimental parameters are reduced.

The invention discloses an organic silicon film with a loose transition layer and a preparation method and application of the organic silicon film, and belongs to the technical field of film separation. The preparation method comprises the following steps: reacting carbon nanotubes with acid, washing and drying to obtain carboxylated carbon nanotubes COOH-CNTs; uniformly mixing the COOH-CNTs with the SiO2-ZrO2 sol, so as to obtain a COOH-CNTs / SiO2-ZrO2 sol; coating a tubular ceramic support body with the porous transition layer, and calcining to obtain a ceramic support body with a loose transition layer; and coating the obtained ceramic support body with the loose transition layer with organic silicon sol, and carrying out heat treatment to form a separation layer, thereby obtaining the organic silicon film. According to the COOH-CNTs, sol particles can be dispersed into a linear grid, and the COOH-CNTs have hydrophilicity and a pore structure, so that more water molecules can quickly pass through the COOH-CNTs, the permeation resistance of the water molecules in a transition layer and a separation layer is reduced, and the COOH-CNTs shows better separation performance in a solution of a pervaporation separation solvent / water.

The disclosure relates to a purification system and a purification bag (6) for use therein, configured for (solar) heat-driven water purification of contaminated water. The purification bag (6) comprises a distillation assembly (601,..60n), comprising: - a contaminated water chamber (30) for collecting contaminated water, the contaminated water chamber (30) comprising a top sheet configured for absorbing heat; - a purified water chamber (50) for collecting purified water, the purified water chamber (50) comprising a condensation sheet configured for collecting condensed purified water; - a membrane (40) arranged between the top sheet and condensation sheet, the membrane dividing the distillation assembly into the contaminated water chamber (30) and the purified water chamber (50), wherein the membrane (40) comprises a membrane sheet configured for separation of the associate part of the contaminated water portion received by the distillation assembly into the purified water portion and a residual water portion comprising water and contaminants remaining in the contaminated water chamber by at least one of membrane distillation and pervaporation through the membrane sheet; wherein the top sheet and the membrane sheet are polymeric sheets that are bonded to each other by welding according to a welding pattern.

This device for recovering water from organic substance-containing drainage water recovers water by treating drainage water that contains a volatile organic substance or a low-molecular-weight organic substance having a molecular weight of at most 200, and comprises a separation membrane module 2 for subjecting the drainage water to a pervaporation treatment by using a separation membrane having a pore diameter of 3.0-4.2 Å, wherein treated water from which the organic substance has been removed by the separation membrane module 2 is recovered.

Systems and methods for dehydrating a mixture of organic liquid and water are disclosed. A mixture of the organic liquid and water is fed to a membrane. The mixture is then subjected to process conditions sufficient to cause pervaporation. A permeate comprising a higher weight percentage of water than the weight percentage of water in the mixture is recovered. A retentate comprising a higher weight percentage of organic liquid than the weight percentage of the organic liquid in the mixture is also recovered.

The invention relates to the technical field of wastewater treatment, and discloses a method for recovering wastewater of a hydrogen peroxide concentration rectifying tower. According to the method, a vacuum evaporation, pervaporation and rectification recovery synergistic process is adopted, gradient utilization of energy is achieved through a heat pump system driven by steam waste heat, and hydrogen peroxide molecules are efficiently and selectively separated through a special composite membrane; the composite membrane is prepared by blending fluoroalkylated polyimide and surface modified titanium dioxide, the synergistic effect is enhanced through molecular structure modification and micro-nano composite, and the pollution resistance and the separation stability of the membrane are remarkably improved; a pervaporation trapped fluid is preheated and then mixed with a raw material liquid for rectification, and deep enrichment and purification of hydrogen peroxide are realized by combining a vacuum low-temperature evaporation technology. According to the method, the hydrogen peroxide component in the wastewater can be efficiently recovered, pollutant emission is greatly reduced, the resource recovery efficiency and the system operation stability are remarkably improved, and the method has outstanding industrial application value.

The present invention belongs to the technical field of ethanol recovery and relates to a preparation method of a C-ZIF-67-derived nanoporous carbon-doped PDMS mixed matrix membrane based on a tubular ceramic carrier and its application in the pervaporation recovery of ethanol from a low-concentration ethanol aqueous solution; the preparation method comprises synthesizing ZIF-67 crystals and carbonizing the ZIF-67 crystals to obtain C-ZIF-67 filler particles; the present invention prepares ZIF-67-derived nanoporous carbon particles by a high-temperature calcination method, fully carbonizes the particles at a certain calcination temperature, and the disappearance of characteristic groups after carbonization can reduce the influence of the surface electrical properties of the particles, and the particle size shrinkage is reduced, which helps to improve the dispersion of the particles in the matrix membrane; at the same time, the MOF skeleton structure is retained after carbonization, and the pore size is enlarged. The carbon material also has strong hydrophobicity. These hydrophobic large-pore separation channels are more conducive to the passage of ethanol molecules, thereby promoting the improvement of the separation effect. Moreover, the separation factor and total flux remain almost unchanged after long-term operation, showing excellent performance and having good application prospects.

The invention relates to an amine regulation-based HOF-21 (at) SA membrane for dehydration of an organic solvent, and belongs to the field of pervaporation separation membranes. A coordination reaction and hydrogen bond assembly are integrated in a gradual decoupling mode, a hydrogen bond organic framework (HOF-21) with a controllable particle size is prepared, and the hydrogen bond organic framework (HOF-21) and a hydrophilic sodium alginate (SA) base material are uniformly blended according to a certain proportion to prepare a membrane casting solution. Polyacrylonitrile (PAN) is used as a supporting material, the interface bonding strength of the separation layer and the supporting layer is regulated and controlled, and the compact composite membrane is prepared through spin coating. The proper pore size of the HOF-21 provides a precise size screening effect, and the separation performance of the membrane on an organic solvent / water is improved; the small-particle-size HOF-21 nano-particles obtained through amine regulation and control are good in dispersion in a solvent and excellent in compatibility with SA. The super-hydrophilic membrane prepared by the invention has high separation performance and wide application prospect.

The invention discloses a pervaporation-membrane distillation coupling separation method for advanced urine water reuse, and belongs to the technical field of water treatment. The method comprises the following steps: soaking a microporous hydrophobic membrane in a strong alkali solution, and treating at 60-80 DEG C for 4-6 hours; preparing a gel precursor solution through a gel monomer and a cross-linking agent, and coating the gel precursor solution on the surface of one side of the hydrophobic microporous membrane; stabilizing the human urine; the coupling separation membrane with the pervaporation functional layer and the hydrophobic substrate is placed in a membrane pool with the effective working area of 10 cm < 2 >; urine and pure water circulate on the two sides of the separation membrane respectively; one side of a urine feeding liquid is heated to 60 DEG C by using a water bath kettle, and 300-500ml of pure water is used as a condensate; after the urine is treated until about 90% of water is recycled, the feed liquid is replaced with pure water to wash the separation membrane. According to the invention, the problems of low water recovery rate and low reuse water quality in the urine treatment process of the traditional distillation membrane are solved, the reuse rate of urine water is greatly improved, the separation membrane is not wetted, and the conductivity of discharged water is greatly reduced.

The invention discloses continuous production equipment and process for grape spirit, and relates to the technical field of grape wine. The production equipment comprises a nanofiltration treatment unit, a continuous pervaporation separation treatment unit and a desulfurization unit. The nanofiltration treatment unit comprises a nanofiltration membrane group and a valve I, and the nanofiltration membrane group is used for separating wine raw materials to obtain nanofiltration permeate. The valve I is used for controlling the circulating filtration process of the nanofiltration treatment unit. The continuous pervaporation separation treatment unit comprises a condensation section and a plurality of treatment sections. The treatment section comprises a pervaporation separation membrane group, and the pervaporation separation membrane group is used for carrying out separation treatment on the nanofiltration permeate liquid to obtain permeate gas. The permeation sides of the plurality of treatment sections converge to the condensation section and are used for condensing the permeation gas to obtain condensate. The desulfurization unit comprises a desulfurization tower and is used for carrying out desulfurization treatment on the condensate. Compared with the prior art, the continuous production equipment and process for the grape spirit can improve the production efficiency and quality.

To provide a water recovery apparatus which recovers water from drain water containing volatile organic matters and organic compounds of a low molecular weight in a closed system space of a spaceship interior or a lunar base or the like, and in which oxygen supply is unnecessary or a small amount thereof is sufficient, and further, which does not require consumables on the premise of exchange of activated carbon or the like.SOLUTION: A water recovery apparatus for recovering water by processing drain water containing volatile organic compounds or low molecular weight organic compounds of a molecular weight of 200 or lower, comprises a separation membrane module 2 for subjecting the drain water to pervaporation processing using a separation membrane with a pore size of 3.0-4.2 Å. The apparatus for recovering water from drain water containing organic compounds recovers treated water from which organic compounds have been removed by to the separation membrane module 2.SELECTED DRAWING: Figure 1

The utility model discloses hydrogen purification and separation equipment based on a pervaporation method, and relates to the technical field of gas separation, the hydrogen purification and separation equipment based on the pervaporation method comprises a pretreatment tank, a pervaporation separation tank and a purification tank, the upper end of the pretreatment tank is provided with a gas inlet pipe, and the pretreatment tank is internally provided with an inner container; sleeves are symmetrically mounted on the outer wall of the pretreatment tank, connecting pipes communicated with the interiors of the sleeves are arranged on the outer walls of the sleeves, filtering assemblies are detachably mounted in the sleeves, and each filtering assembly comprises a first filtering part, a second filtering part and a guiding part; according to the gas separation device, particles in the gas can be filtered by arranging the filtering assembly, so that the separation effect is improved, and multi-stage filtering can be carried out by arranging the first filtering part, the second filtering part and the guiding part, so that the filtering effect is ensured, and the separation effect is further improved.

A high salinity water purification system and process, including a forward osmosis system and a reverse osmosis or nanofiltration system. A solids membrane separation system removes solids from the influent water being processed. A pervaporation (PV) system eliminates liquid impurities from the influent water being processed.

The application belongs to the technical field of novel separation membrane materials, and discloses an ionic covalent organic framework membrane as well as a preparation method and application thereof. An amine monomer and an aldehyde monomer are respectively dissolved in water and an organic solvent, and a continuous defect-free ionic covalent organic framework membrane is formed in situ on the surface of a carboxylated porous support base membrane through a limited interface polymerization method. The membrane structure and separation performance can be optimized by adjusting the monomer concentration and reaction time. The preparation process is simple and controllable, the prepared membrane is applied to pervaporation butanol-water separation, and high permeability and high selectivity are exhibited, and the prepared membrane also has good long-term operation stability. In addition, the prepared membrane can also be applied to other kinds of alcohol-water separation and pervaporation salt-water separation, and has good universal application.

The application provides a composite pervaporation desalination membrane and a preparation method and application thereof. The composite pervaporation desalination membrane comprises a separation layer with a separation function and an organic porous base membrane layer serving as a support; the raw materials of the separation layer comprise a polyvinyl alcohol aqueous solution, a PFSA-g-GO nanocomposite and a crosslinking agent, the addition amount of the PFSA-g-GO nanocomposite is 0.2-4.5 mass%, the addition amount of the crosslinking agent is 1-10 mass%, and the mass% is the percentage of the mass of each component to the mass of the polyvinyl alcohol; and the organic porous base membrane layer is a polyacrylonitrile membrane or a polyethersulfone membrane. The preparation method is simple and easy to implement, and has low cost, and can simultaneously improve the water flux and desalination rate of the composite pervaporation desalination membrane.

The invention discloses a method for preparing a molecular sieve membrane from a super-dilute reaction solution, and belongs to the technical field of inorganic membrane materials and membrane separation. The method comprises the following steps: preparing a mixed solution of an aluminum source and a silicon source through an inorganic alkali system, aging to obtain a first reaction solution, and performing hydro-thermal synthesis to obtain a high-activity nano FAU seed crystal; uniformly loading seed crystals on the surface of the porous support body to form a compact seed crystal layer; a super-dilute second reaction solution is further used for short-time hydrothermal growth, and controllable construction of the FAU molecular sieve membrane is achieved. According to the method, the ultrathin FAU film with crystal alternation and compact structure can be obtained, film defects are remarkably reduced, and an organic template agent and high-temperature calcination treatment are not needed. The obtained membrane shows excellent performance in pervaporation dehydration, the total flux can reach 6.3 kg / (m.h), the separation factor is as high as 1413, and the membrane is far superior to an FAU membrane prepared from a traditional micron seed crystal and a high-concentration solution system, and can be widely applied to the fields of organic solvent dehydration, green solvent purification, gas separation, membrane reactors and the like.

The invention belongs to the technical field of separation membranes, and discloses a composite pervaporation desalination membrane and a preparation method and application thereof, the composite pervaporation desalination membrane sequentially comprises a bottom layer, a positively charged porous support layer and a compact selection layer; the positively charged porous supporting layer comprises a sublayer and a surface layer, the sublayer is attached to the bottom layer, and a compact selection layer is attached to the surface layer; the dense selection layer is made of polyvinyl alcohol crosslinked by amino-terminated hyperbranched polyamide and poly (4-styrenesulfonic acid-co-maleic acid) sodium salt. The composite pervaporation desalination membrane provided by the invention has a moderate surface pore size of the support layer, the support layer for enhancing the charge effect and the loose hydrophilic compact selection layer, and further has high permeation flux on the premise of ensuring efficient interception of salt.

This invention discloses a method for preparing an internally pressurized MOF-based hollow fiber composite membrane module, belonging to the field of membrane separation technology. The invention involves introducing an aqueous solution containing metal ions and an organic solution containing organic ligands into the shell side and tube side of a hollow fiber membrane module, respectively. By controlling the number of reactions between metal ions and organic ligands on the inner surface of the hollow fiber membrane, a continuous MOF functional layer is precisely constructed. Subsequently, a low-concentration polymer solution is used to repair defects in the MOF layer, resulting in an internally pressurized MOF-based hollow fiber composite membrane module, which is then applied to pervaporation ethanol / water separation. This method simplifies the preparation process of the internally pressurized hollow fiber composite membrane module; the thin inner surface MOF layer reduces molecular diffusion resistance and enhances molecular mass transfer; the surface-coated polymer matrix effectively repairs MOF layer defects, further enhancing molecular separation selectivity and effectively protecting the MOF functional layer; and it enhances the long-term stability of the membrane module.

Described herein is a preparation method of C-ZIF-67-derived nano-porous carbon doped PDMS mixed matrix membrane based on a tubular ceramic carrier and its application in pervaporation of low-concentration ethanol aqueous solution to recover ethanol by synthesizing ZIF-67 crystals and carbonizing the ZIF-67 crystal to obtain C-ZIF-67 filler particles. According to the present application, the nano-porous carbon particles derived from ZIF-67 are prepared by a high-temperature calcination method, and are fully carbonized at a certain calcination temperature, so that the disappearance of characteristic groups after carbonization can reduce the influence of surface electrical properties, and the particle size is reduced. At the same time, the MOF skeleton structure is still retained after carbonization, the pore size is enlarged, and the carbon material also has strong hydrophobicity.

The invention belongs to the technical field of novel separation membrane materials, and discloses an ionic covalent organic framework membrane as well as a preparation method and application thereof. An amine monomer and an aldehyde monomer are respectively dissolved in water and an organic solvent, and the continuous defect-free ionic covalent organic framework membrane is formed by in-situ growth on the surface of a carboxylated porous support base membrane through a limited interface polymerization method. And the membrane structure and the separation performance can be optimized by regulating and controlling the monomer concentration and the reaction time. The preparation process is simple, convenient and controllable, the prepared membrane is applied to pervaporation butanol-water separation, high permeability and high selectivity are shown, and good long-term operation stability is achieved. In addition, the prepared membrane can also be applied to separation of other types of alcohol-water and separation of pervaporation salt-water, and has good universality application.

A highly stable ceramic-based sub-nanoporous graphene composite membrane and its precision separation applications are disclosed, belonging to the field of environmental membrane separation technology. This composite membrane introduces an inorganic transition layer on the outer surface of an inorganic ceramic substrate with sheet-like, hollow fiber, or tubular configurations, increasing its bonding strength with the graphene separation layer. The thickness and pore structure of the composite membrane are precisely controlled by changing the filtration time, filtrate concentration, crosslinking agent content, and high-temperature reduction temperature and time. Through optimization of the preparation conditions, a highly stable ceramic-based sub-nanoporous graphene composite membrane was obtained. This composite membrane can achieve efficient and precise separation applications through pervaporation processes, such as seawater desalination, high-salinity wastewater desalination, boron removal from seawater and geothermal wastewater, and other wastewater (such as antibiotic wastewater and low-concentration volatile organic pollutant wastewater), exhibiting excellent separation performance and stability in extreme environments.

The application belongs to the technical field of separation membranes, and discloses a zwitterionic modified graphene oxide double-layer structure composite membrane and a preparation method thereof. First, a graphene oxide layer is formed on the surface of a porous supporting base membrane by a vacuum-assisted self-assembly method, and then a zwitterionic layer is constructed on the surface of the graphene oxide layer by a biomimetic co-deposition method to obtain a double-layer structure composite membrane. The zwitterionic layer on the top can improve the hydrophilicity of the membrane surface, strengthen the dissolution process of water molecules on the membrane surface, and improve the separation selectivity; the graphene oxide layer on the bottom serves as a rapid mass transfer channel for molecules, strengthens the diffusion process of molecules, and improves the permeability of the membrane; dopamine can improve the interfacial compatibility between layers, which is conducive to the stability of the membrane structure. The composite membrane prepared by the application can realize the pervaporation process of preferential dissolution and preferential diffusion of water molecules, obtain high permeation flux and high separation factor, and maintain good long-term operation stability, and has certain universality, good application prospect, and the like.

The application discloses a kind of zwitterionic covalent organic framework membranes and preparation method and application thereof, belong to the technical field of separation membrane material, continuous covalent organic framework membrane is in-situ constructed on the surface of porous support base film by interfacial polymerization reaction, then the membrane is sequentially soaked in organic phase solution containing polyacyl chloride and aqueous solution containing zwitterion, and zwitterionic covalent organic framework membrane is obtained after heat treatment.The continuous covalent organic framework membrane hole channel is through, can be used as the rapid transfer channel of molecule, it is favorable to obtain high permeation flux;Zwitterionic is carried out on its surface, on the one hand, the hydrophilicity of membrane surface can be improved, on the other hand, the pore structure of membrane surface can be controlled, while forming water selective transport channel, competitive alcohol molecules are excluded.The preparation method of the application is simple and controllable, and the prepared composite membrane is used in pervaporation ethanol dehydration process, and excellent separation performance and long-term operation stability are shown.

A purification method for separating and purifying an organic solvent from a liquid mixture of an organic solvent and water, the organic solvent having a boiling point of more than 100° C. at 1 atm, includes the steps of: passing the liquid mixture through a first ion exchange device; supplying the liquid mixture discharged from the first ion exchange device to a pervaporation device to selectively separate water component; supplying the organic solvent recovered from the concentration side of the pervaporation device to an evaporator to obtain a purified organic solvent; and passing, through the second ion exchange device, a portion of liquid containing the organic solvent and flowing at a first position subsequent to the first ion exchange device. The liquid discharged from the second ion exchange device is returned to a second position which is at a preceding stage of the pervaporation device.