WO2018112781A1

WO2018112781A1 - Reverse osmosis membrane and method of processing the same

Info

Publication number: WO2018112781A1
Application number: PCT/CN2016/111255
Authority: WO
Inventors: Changquan QIU; Minling Liu; Yubin LV; Chaojun Liu
Original assignee: Honeywell International Inc.
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2018-06-28

Abstract

A reverse osmosis membrane and a method of processing the same are disclosed. The method includes forming a polyamide material on a microporous membrane material by reacting a polyfunctional amine with a polyfunctional acid chloride on the microporous membrane material and adding water and a water soluble organic solvent to the reaction of the polyfunctional amine with the polyfunctional acid chloride.

Description

REVERSE OSMOSIS MEMBRANE AND METHOD OF PROCESSING THE SAME

Technical Field

The present disclosure relates to reverse osmosis membranes, and methods of processing the same.

Background

The consumption of water is continually increasing, due to, for example, population growth and industrial development. This increased water consumption, however, is resulting in (e.g., producing and/or generating) an increased amount of contaminated and/or waste water, which presents an increasing health and/or environmental threat. As such, water purification is becoming an important issue, especially in developing areas.

One approach (e.g., process) that can be used for purifying water is reverse osmosis. Reverse osmosis is a water purification (e.g., filtering) process in which pressure is used to force water through a semipermeable membrane, which removes particles from the water. Reverse osmosis can be used, for instance, to convert salt water (e.g., sea water) and/or brackish water into clean drinking water by removing the salt and other effluent materials from the water. As an additional example, reverse osmosis can be used to remove potentially harmful contaminants, such as heavy metals and/or pesticide residues, from the water.

Existing reverse osmosis membranes are typically formed in a layered, flat sheet type structure using an interfacial polymerization process. However, existing interfacial polymerization processes may not be capable of producing reverse osmosis membranes having a high enough water flux or high enough rejection rate for residential (e.g., domestic) uses and settings.

Brief Description of the Drawings

Figures 1A-1B illustrate process steps associated with forming a reverse osmosis membrane in accordance with one or more embodiments of the present disclosure.

Figure 2 illustrates an image of a microporous membrane material of a reverse osmosis membrane processed in accordance with one or more embodiments of the present disclosure.

Figure 3 illustrates an image of a polyamide material of a reverse osmosis membrane processed in accordance with one or more embodiments of the present disclosure.

Detailed Description

A reverse osmosis membrane and a method of processing the same are described herein. For example, one or more embodiments include forming a polyamide material on a microporous membrane material by reacting a polyfunctional amine with a polyfunctional acid chloride on the microporous membrane material and adding water and a water soluble organic solvent to the reaction of the polyfunctional amine with the polyfunctional acid chloride.

Reverse osmosis membranes processed in accordance with the present disclosure (e.g. using an interfacial polymerization process that includes water and a water soluble organic solvent) may have a better and/or higher performance than reverse osmosis membranes processed in accordance with previous approaches (e.g., using previous interfacial polymerization processes) . For example, reverse osmosis membranes processed in accordance with the present disclosure may have a higher water flux and/or a higher rejection rate than reverse osmosis membranes processed in accordance with previous approaches. As such, reverse osmosis membranes processed in accordance with the present disclosure may be more suitable to residential (e.g., domestic) uses and settings than reverse osmosis membranes processed using previous approaches.

In the following detailed description, reference is made to the accompanying drawings that form a part hereof. The drawings show by way of illustration how one or more embodiments of the disclosure may be practiced.

These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice one or more embodiments of this disclosure. It is to be understood that other embodiments may be utilized and that mechanical, electrical, and/or process changes may be made without departing from the scope of the present disclosure.

As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, combined, and/or eliminated so as to provide a number of additional embodiments of the present disclosure. The proportion and the relative scale of the elements provided in the figures are intended to illustrate the embodiments of the present disclosure, and should not be taken in a limiting sense.

The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 102 may reference element “02” in Figures 1A and 1B, and a similar element may be referenced as 202 in Figure 2.

As used herein, “a” or “a number of” something can refer to one or more such things. For example, “a number of structures” can refer to one or more structures.

Figures 1A-1B illustrate process steps associated with forming (e.g., making) a reverse osmosis membrane 100 in accordance with one or more embodiments of the present disclosure. For example, Figure 1A illustrates a schematic cross-sectional view of a microporous membrane material 102 of reverse osmosis membrane 100.

Microporous membrane material 102 can be, for example, a polysulfone (PSf) material, such as, for instance, PSf-1 or PSf-2. However, embodiments of the present disclosure are not so limited. For instance, in some embodiments, microporous membrane material 102 can be a polyethersulfone (PES) material.

Microporous membrane material 102 can be a porous ultrafiltration (UF) membrane material. For example, in embodiments in which microporous membrane material 102 is a PSf material, microporous membrane material 102 can have a mean pore size of 7 to 15 nanometers (nm) . Further, microporous membrane material 102 can have a thickness (e.g., distance from top to bottom) of 30 to 80 micrometers (μm) , a contact angle of 60 to 90 degrees, and a water flux of 160 to 300 Liters/m²/hour/bar (LMH/bar) .

Microporous membrane material 102 can be formed, for example, by casting a polysulfone/polyethylene glycol/N-methyl pyrrolidone (PSf/PEG/NMP) solution on a polyethylene terephthalate (PET) material (e.g., fabric) . This structure can be exposed to air (e.g., for 30 seconds) , and then immersed in water at ambient (e.g., room) temperature.

The PSf/PEG/NMP solution can be cast on the PET material using, for example, a casting knife. Further, the PSf/PEG/NMP solution can have a PSf concentration level of 20 weight percent (wt. ％) , a PEG concentration level of 2 wt. ％, and an NMP concentration level of 78％, for instance. The PET material may have a thickness of, for instance, 100 micrometers (μm) .

Figure 1B illustrates a schematic cross-sectional view of the structure shown in Figure 1A after a subsequent processing step. In Figure 1B, a polyamide material 104 is formed on microporous membrane material 102. For instance, polyamide material 104 is formed on the top surface of microporous membrane material 102, as illustrated in Figure 1B.

Microporous membrane material 102 can be the substrate for polyamide material 104. Further, polyamide material 104 can be a thin material as compared to microporous membrane material 102 (e.g., microporous membrane material 102 may be much thicker than polyamide material 104) , as illustrated in Figure 1B.

Polyamide material 104 can be formed on microporous membrane material 102 by, for example, reacting a polyfunctional amine with a polyfunctional acid chloride on microporous membrane material 102 (e.g., on the top surface of microporous membrane material 102) , and adding water and a water soluble organic solvent to the reaction of the polyfunctional amine with the polyfunctional acid chloride. The reaction of the polyfunctional amine with the polyfunctional acid chloride can be (e.g. occur as) , for example, part of an interfacial polymerization process. For instance, polyamide material 104 can be formed on microporous membrane material 102 using an interfacial polymerization process that includes a water soluble organic solvent as an additive in a water phase solution.

For example, the interfacial polymerization process can include contacting the top surface of microporous membrane material 102 with an amine solution and a water soluble organic solvent, and then contacting the top surface of microporous membrane material 102 with a mixture of an acid chloride solution after contacting the top surface with the amine solution. Contacting the top surface of microporous membrane material 102 with the amine solution can include, for instance, immersing microporous membrane material 102 in the amine solution, and then removing the excess amine solution from the top surface of microporous membrane material 102 after the immersion. Microporous membrane material 102 may remain immersed in the amine solution and water soluble organic solvent for two minutes, and the top surface of microporous membrane material 102 may subsequently remain in contact with the mixture of the acid chloride solution for one minute, for instance. The structure can then be washed with deionized water.

The polyfunctional amine can be, for example, m-phenylenediamine (MPD) , and the polyfunctional acid chloride can be, for example, trimesoyl chloride (TMC) . For instance, in some embodiments, the amine solution can have an MPD concentration level of 0.5 wt. ％, and the acid chloride solution can have a TMC concentration level of 0.08 wt. ％. However, embodiments of the present disclosure are not limited to this example, For instance, in some embodiments, the amine solution can have an MPD concentration level of 0.5 to 1.5 wt. ％, and the acid chloride solution can have a TMC concentration level of 0.08 to 0.2 wt. ％.

The water soluble organic solvent can be, for example, dimethyl sulfoxide (DMSO) . For instance, in some embodiments, the mixture of the MPD solution, the water, and the water soluble organic solvent (e.g., the water phase solution) may have a DMSO/water ratio of 10/90. However, embodiments of the present disclosure are not limited to this example. For instance, in some embodiments, the mixture may have a DMSO/water ratio of 2.5/97.5. Further, in some embodiments, the water soluble organic solvent can be N-methyl pyrrolidone (NMP) or N-dimethylformamide (DMP) . For instance, the mixture may have an NMP/water or DMP/water ratio of 2.5/97.5.

In some embodiments, a ketone co-solvent may also be added to the reaction of the polyfunctional amine with the polyfunctional acid chloride. For example, the mixture of the acid chloride solution used in the interfacial polymerization process may also include a ketone co-solvent.

The ketone co-solvent can be, for example, acetone or butanone. For instance, in some embodiments, the mixture of the acid chloride solution and ketone co-solvent can have an acetone/hexane concentration level of 2.0 wt. ％. However, embodiments of the present disclosure are not limited to this example. For instance, in some embodiments, the mixture of the acid chloride solution and ketone co-solvent can have an acetone/hexane concentration level of 0.0 to 4.0 wt. ％.

Reverse osmosis membrane 100 illustrated in Figure 1B can be part of (e.g., used in) a reverse osmosis water purification (e.g., filtering) system. For instance, pressure can be used to force water through membrane 100, and membrane 100 can remove particles from the water as it flows through the membrane, as will be appreciated by one of skill in the art.

As an example, reverse osmosis membrane 100 can be used to remove potentially harmful contaminants, such as heavy metals (e.g., arsenic, mercury, lead, cadmium, etc. ) and/or pesticide residues, from the water. Further, membrane 100 can be part of a point-of-use water purification system, such as, for instance, a residential (e.g., domestic) water purification system used to filter the tap and/or drinking water of a residence. However, embodiments of the present disclosure are not limited to a particular type of use or application for membrane 100.

During a reverse osmosis water purification process that uses reverse osmosis membrane 100 (e.g. during which pressure is used to force water through membrane 100) , polyamide material 104 can selectively separate contaminants, such as heavy metals and/or pesticide residues, for instance, from the water. That is, polyamide material 104 can be a selective material that can selectively separate the contaminants from the water.

Reverse osmosis membrane 100 can have a high water flux and a high rejection rate. For example, reverse osmosis membrane 100 can have a water flux of 3.5 to 7.1 LMH/bar, and a rejection rate of at least 91.6％. As such, reverse osmosis membrane 100 may be suitable to residential (e.g., domestic) uses and settings, such as, for instance, filtering the tap and/or drinking water of a residence.

As an example, reverse osmosis membrane can have a water flux of at least 6.9 LMH/bar and a rejection rate of at least 96.7％in embodiments in which the amine solution used in the interfacial polymerization process used to form polyamide material 104 on microporous membrane material 102 has an MPD concentration level of 0.5 wt. ％, the acid chloride solution used in the interfacial polymerization process has a TMC concentration level of 0.08 wt. ％, and the mixture of the acid chloride solution, organic solvent, and ketone co-solvent used in the interfacial polymerization process has an acetone/hexane concentration level of 2.0 wt. ％and a DMSO/water ratio of 10/90. However, embodiments of the present disclosure are not limited to this example.

Figure 2 illustrates an image of a microporous membrane material 202 of a reverse osmosis membrane processed in accordance with one or more embodiments of the present disclosure. The image shown in Figure 2 is a scanning electron microscope (SEM) image of microporous membrane material 202.

Microporous membrane material 202 can be, for example, microporous membrane material 102 of reverse osmosis membrane 100 previously described in connection with Figures 1A-1B. For example, the image shown in Figure 2 can be a cross-sectional view of reverse osmosis membrane 100 illustrated in Figure 1A (e.g., after microporous membrane material 102 has been formed, but before polyamide material 104 is formed on microporous membrane material 102) .

For example, microporous membrane material 202 can be a PSf material or a PES material, as previously described in connection with Figure 1A. Further, microporous membrane material 202 can be a porous UF membrane material with a thickness of 30 to 80 μm, a contact angle of 60 to 90 degrees, and a water flux of 160 to 300 LMH/bar, as previously described in connection with Figure 1A. Microporous membrane material 202 can be formed, for example, by casting a PSf/PEG/NMP solution on a PET material, as previously described in connection with Figure 1A.

Figure 3 illustrates an image of a polyamide material 304 of a reverse osmosis membrane processed in accordance with one or more embodiments of the present disclosure. The image shown in Figure 3 is an SEM image of polyamide material 304.

Polyamide material 304 can be, for example, polyamide material 104 of reverse osmosis membrane previously described in connection with Figures 1A-1B. For example, the image shown in Figure 3 can be a top view of reverse osmosis membrane 100 illustrated in Figure 1B (e.g., after polyamide material 104 has been formed on microporous membrane material 102) . That is, the image shown in Figure 3 can be a view of the top surface of polyamide material 104.

For example, polyamide material 304 can a thin, selective material, as previously described in connection with Figure 1B. Polyamide material 304 can be formed using an interfacial polymerization process that includes a water soluble organic solvent as an additive in a water phase solution, as previously described in connection with Figure 1B.

Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that any arrangement calculated to achieve the same techniques can be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments of the disclosure.

It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description.

The scope of the various embodiments of the disclosure includes any other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are grouped together in example embodiments illustrated in the figures for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the embodiments of the disclosure require more features than are expressly recited in each claim.

Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

A method of processing a reverse osmosis membrane (100) , comprising:

forming a polyamide material (104, 304) on a microporous membrane material (102, 202) by:

reacting a polyfunctional amine with a polyfunctional acid chloride on the microporous membrane material (102, 202) ； and

adding water and a water soluble organic solvent to the reaction of the polyfunctional amine with the polyfunctional acid chloride.
The method of claim 1, wherein the method includes reacting the polyfunctional amine with the polyfunctional acid chloride as part of an interfacial polymerization process.
The method of claim 1, wherein the method includes forming the polyamide material (104, 304) on the microporous membrane material (102, 202) by adding a ketone co-solvent to the reaction of the polyfunctional amine with the polyfunctional acid chloride.
The method of claim 3, wherein the ketone co-solvent is acetone.
The method of claim 1, wherein the water soluble organic solvent is dimethyl sulfoxide (DMSO) .
The method of claim 1, wherein the water soluble organic solvent is N-methyl pyrrolidone (NMP) .
The method of claim 1, wherein the water soluble organic solvent is N-dimethylformamide (DMP) .
The method of claim 1, wherein:

the polyfunctional amine is m-phenylenediamine (MPD) ； and

the polyfunctional acid chloride is trimesoyl chloride (TMC) .
The method of claim 1, wherein the microporous membrane material (102, 202) is a polysulfone material.
The method of claim 1, wherein the microporous membrane material (102, 202) has a thickness of 30 to 80 micrometers (μm) , a contact angle of 60 to 90 degrees, and a water flux of 160 to 300 Liters/m²/hour/bar (LMH/bar) .