CERAMIC GO/PEI NANOMEMBRANE BY LAYER-BY-LAYER ASSEMBLY BASED ON COVALENT BOND USING EDC CHEMISTRY AND METHOD FOR MANUFACTURING THE SAME

Abstract

The present disclosure relates to a ceramic graphene oxide nanofiltration membrane which is high in mechanical stability while having ion removal ability by alternately stacking GO and PEI on a ceramic nanomembrane by allowing a carboxyl group (—COOH) and an amine group (—NH.sub.2) to form a covalent bond in the presence of N-ethyl-N′-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC), thereby forming an amide group (—CONH), and a method for manufacturing the same.

Claims

1. A ceramic nanofiltration membrane characterized in that graphene oxide (GO) and polyethyleneimine (PEI) are alternately coated on the surface of the ceramic nanofiltration membrane, and the GO and the PEI allow a carboxyl group (—COOH) and an amine group (—NH.sub.2) to form a covalent bond, thereby forming an amide group (—CONH).

2. The ceramic nanofiltration membrane of claim 1, wherein the ceramic nanofiltration membrane is made of any one selected from the group consisting of titania, alumina, silica, and zirconia.

3. The ceramic nanofiltration membrane of claim 1, wherein the GO and the PEI allow a carboxyl group (—COOH) and an amine group (—NH.sub.2) to form a covalent bond in the presence of N-ethyl-N′-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC), thereby forming an amide group (—CONH).

4. The ceramic nanofiltration membrane of claim 1, wherein the GO and the PEI are stacked on the surface of the ceramic nanofiltration membrane by a layer-by-layer assembly.

5. The ceramic nanofiltration membrane of claim 4, wherein the GO and the PEI allow a carboxyl group (—COOH) and an amine group (—NH.sub.2) to form a covalent bond in the presence of EDC, thereby forming an amide group (—CONH) so that no crosslinker is required to bind GO and PEI.

6. A method for manufacturing a ceramic nanofiltration membrane, comprising: a step 1 of immersing a ceramic membrane in a PEI solution to adsorb PEI on the surface of the ceramic membrane; a step 2 of heating the PEI-adsorbed ceramic membrane to immobilize PEI; a step 3 of adding an EDC solution to a GO solution and immersing the PEI-immobilized ceramic membrane in the GO solution so that a carboxyl group of GO and an amine group of PEI are covalently bonded in the presence of EDC to form an amide group; a step 4 of adding the EDC solution to the PEI solution and immersing the ceramic membrane therein so that the carboxyl group of GO and the amine group of PEI are covalently bonded in the presence of EDC to form the amide group; and a step 5 of repeating the steps 3 and 4 to laminate a GO/PEI multilayer thin film on the ceramic membrane.

7. The method of claim 6, wherein the time for immersing the ceramic membrane of the step 1 in the PEI solution and the time for immersing the PEI-immobilized ceramic membrane of the step 3 in the GO solution are 6 to 24 hours.

8. The method of claim 6, wherein the PEI solution of the step 1 has a concentration of 1,000 to 2,000 mg/L, the GO solution of the step 3 has a concentration of 1,000 to 2,000 mg/L, and the EDC solution of the step 3 has a concentration of 2 to 5 mmol/L.

9. The method of claim 6, wherein the PEI-adsorbed ceramic membrane of the step 2 has a heating temperature of 60° C. to 100° C.

10. A ceramic nanofiltration membrane manufactured by the method for manufacturing the ceramic nanofiltration membrane according to any one of claims 6 to 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a diagram showing a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane separately depending on their functions;

[0029] FIG. 2 is a diagram explaining that a carboxyl group (—COOH) and an amine group (—NH.sub.2) may form an amide group (—CONH) by forming a covalent bond in the presence of EDC;

[0030] FIG. 3 is a diagram schematizing a process of coating polyethyleneimine (PEI) on a ceramic membrane according to an embodiment of the present disclosure; and

[0031] FIG. 4 is a diagram schematizing a ceramic membrane in which graphene oxide (GO) and PEI are cross-coated on the ceramic membrane according to the present disclosure.

[0032] The significance of features and advantages of the present disclosure will be better understood with reference to the accompanying drawings. However, it should be understood that the drawings are devised for purposes of illustration only and do not define the limitations of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present disclosure pertains may easily implement the present disclosure. However, since the description of the present disclosure is merely embodiments for structural or functional description, the scope of rights of the present disclosure should not be construed as being limited by the embodiments described in the text. That is, since the embodiments may be variously changed and may have various forms, it should be understood that the scope of rights of the present disclosure includes equivalents capable of realizing the technical idea. Further, since the object or effect presented in the present disclosure does not mean that a specific embodiment should include all of them or only such an effect, it should not be understood that the scope of rights of the present disclosure is limited thereby.

[0034] The meaning of the terms described in the present disclosure should be understood as follows.

[0035] Terms such as “first”, “second”, etc. are for distinguishing one element from other elements, and the scope of rights should not be limited by these terms. For example, a first element may be termed a second element, and similarly, the second element may also be termed the first element. When a component is referred to as being “connected” to other components, it may be directly connected to the other components, but it should be understood that another component may exist in the middle thereof. On the other hand, when it is mentioned that a certain component is “directly connected” to other component, it should be understood that another component does not exist in the middle thereof. Meanwhile, other expressions describing the relationship between components, that is, “between” and “directly between” or “neighboring to” and “directly adjacent to”, etc., should also be interpreted similarly.

[0036] The singular expression should be understood as including the plural expression unless the context clearly dictates otherwise, it is intended to designate that a term such as “comprises”, or “have”, refers to the specified feature, number, step, operation, component, part, or a combination thereof exists, and it should be understood that it does not preclude the possibility of the existence or addition of one or more other features or numbers, steps, operations, components, parts, or combinations thereof in advance.

[0037] All terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure pertains, unless otherwise defined. Terms defined in generally used dictionaries should be interpreted as having the meaning consistent with that in the context of the related art, and may not be interpreted as having an ideal or excessively formal meaning unless explicitly defined in the present disclosure.

[0038] The inventors of the present disclosure used EDC chemistry in order to cross-coat GO and PEI on the surface of a ceramic membrane. The ceramic membrane may be made of a material such as titania, alumina, silica, or zirconia, and it is preferable to use a membrane containing a hydroxyl group in its surface as described above.

[0039] A method of cross-coating GO and PEI on the ceramic membrane surface using EDC chemistry is as follows.

[0040] First, (step 1) PEI is adsorbed on the surface of the ceramic membrane by immersing a ceramic membrane in a PEI solution.

[0041] The time for immersing the ceramic membrane in the PEI solution is preferably 6 to 24 hours, most preferably 12 hours. If it is 6 hours or less, there may be insufficient time for the material to be sufficiently adsorbed into the solution, and if it is 24 hours or more, there may be a problem in that the adsorbed material is resuspended.

[0042] The PEI solution may have a concentration of 1,000 to 2,000 mg/L. At this time, if it is 1,000 mg/L or less, a problem may occur that the material may not sufficiently contact on the support, and if it is 2,000 mg/L or more, an aggregation phenomenon between the solutes in the solution may occur.

[0043] Next (step 2), the PEI-adsorbed ceramic membrane is heated at high temperatures to immobilize PEI. The PEI-adsorbed ceramic membrane may be heated to a temperature of 60° C. to 100° C. At this time, when it is 60° C. or less, PEI may not be sufficiently immobilized on the membrane, and when it is a high temperature of 100° C. or more, the PEI structure may be deformed.

[0044] Next (step 3), an EDC solution is added to a GO solution, and the PEI-immobilized ceramic membrane is immersed in the GO solution so that a carboxyl group of GO and an amine group of PEI are covalently bonded in the presence of EDC to form an amide group.

[0045] The GO solution may have a concentration of 1,000 to 2,000 mg/L. At this time, if it is 1,000 mg/L or less, a problem may occur that the material may not sufficiently contact on the support, and if it is 2,000 mg/L or more, an aggregation phenomenon between the solutes in the solution may occur.

[0046] The EDC solution may have a concentration of 2 to 5 mmol/L. At this time, if it is 2 mmol/L or less, there may be a problem that the EDC molecule may not sufficiently promote an amidation reaction, and if it is 50 mmol/L or more, a problem of lengthening the reaction time may occur due to the production of urea by-products. It has been reported that no urea by-products were produced at an EDC concentration of 5 mmol/L.

[0047] The time for immersing the PEI-immobilized ceramic membrane in the GO solution is preferably 6 to 24 hours, most preferably 12 hours. If it is 6 hours or less, there may be insufficient time for the material to be sufficiently adsorbed into the solution, and if it is 24 hours or more, there may be a problem in that the adsorbed material is resuspended.

[0048] (Step 4) The EDC solution is added to the PEI solution, and the ceramic membrane is immersed therein so that the carboxyl group of GO and the amine group of PEI are covalently bonded in the presence of EDC to form the amide group (see FIG. 3).

[0049] (Step 5) A ceramic graphene oxide nanofiltration membrane is manufactured by repeating the steps 3 and 4 to laminate a GO/PEI multilayer thin film on the ceramic membrane (see FIG. 4).

EXAMPLE

[0050] (Step 1) A ceramic membrane is immersed in a PEI solution (1,000 mg/L) for 1 hour to adsorb PEI on the ceramic membrane surface.

[0051] (Step 2) The PEI-adsorbed ceramic membrane is heated at a high temperature (105° C.) to immobilize PEI.

[0052] (Step 3) An EDC solution (4 mmol/L) is added to a GO solution (1,000 mg/L), and the PEI-immobilized ceramic membrane is immersed therein for 24 hours so that a carboxyl group of GO and an amine group of PEI are covalently bonded in the presence of EDC to form an amide group.

[0053] (Step 4) The EDC solution (4 mmol/L) is added to the PEI solution (1,000 mg/L), and the ceramic membrane is immersed therein for 24 hours so that the carboxyl group of GO and the amine group of PEI are covalently bonded in the presence of EDC to form the amide group.

[0054] (Step 5) A ceramic graphene oxide nanofiltration membrane is manufactured by repeating the steps 3 and 4 to laminate a GO/PEI multilayer thin film on the ceramic membrane.