PREPARATION METHOD OF TI3C2TX MXENE QUANTUM DOT (MQD)-MODIFIED POLYAMIDE (PA) REVERSE-OSMOSIS (RO) MEMBRANE

Abstract

The present disclosure belongs to the technical field of membrane separation, and discloses a preparation method of a Ti.sub.3C.sub.2T.sub.x MXene quantum dot (MQD)-modified polyamide (PA) reverse osmosis (RO) membrane. The preparation method includes the following steps: subjecting a Ti.sub.3C.sub.2T.sub.x MXene material to liquid nitrogen intercalation and interlayer expansion to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial; preparing an aqueous phase solution with the Ti.sub.3C.sub.2T.sub.x MQD nanomaterial and an organic phase solution; soaking an ultrafiltration (UF) base membrane in the aqueous phase solution , and removing the aqueous phase solution on a surface of the UF base membrane through blow-drying; soaking the second UF base membrane in the organic phase solution to allow interfacial polymerization to form an active layer; and allowing a composite membrane obtained after the interfacial polymerization to stand, followed by a heat treatment to further promote the interfacial polymerization.

Claims

1. A preparation method of a Ti.sub.3C.sub.2T.sub.x MXene quantum dot (MQD)-modified polyamide (PA) reverse osmosis (RO) membrane, comprising the following steps: S1: subjecting a Ti.sub.3C.sub.2T.sub.x MXene material to liquid nitrogen intercalation and interlayer expansion to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial; S2: adding the Ti.sub.3C.sub.2T.sub.x MQD nanomaterial to an aqueous polyamine solution to obtain an aqueous phase solution ; S3: preparing an organic phase solution, wherein the organic phase solution is a polyacyl chloride solution; and S4: immersing an ultrafiltration (UF) base membrane in the aqueous phase solution, then removing the aqueous phase solution from a surface of the UF base membrane through blow-drying; immersing the UF base membrane in the organic phase solution to allow formation of an active layer on the UF base membrane through an interfacial polymerization reaction, resulting in a composite membrane; and allowing the composite membrane to stand, followed by subjecting it to a heat treatment to promote the interfacial polymerization reaction.

2. The preparation method according to claim 1, wherein S1 comprises: S11: adding a Ti.sub.3AlC.sub.2 powder to an HF solution, and stirring a resulting mixture at 30? C. to 50? C. for 48 h to 72 h to perform etching and to obtain an etched powder; washing the etched powder repeatedly with deionized water and absolute ethanol until a pH of a resulting washing solution is higher than 6.5; and lyophilizing the resulting washing solution by conducting vacuum-drying at ?70? C. to -90? C.for 12 h to 36 h to obtain the Ti.sub.3C.sub.2T.sub.x MXene material powder; and S12: adding 1 g to 10 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in S11 to a polytetrafluoroethylene (PTFE) beaker, pouring 10 mL to 50 mL of liquid nitrogen into the beaker, and placing the beaker at room temperature for 3 min to 10 min; adding 30 mL to 50 mL of deionized water at 80? C. to 100? C. to the beaker to react for 3 min to 5 min, and stirring a resulting reaction mixture at room temperature for 24 h to 36 h; filtering the reaction mixture through a filter membrane with a pore size of 220 nm, and centrifuging a resulting filtrate at 10,000 r/min for 10 min to 30 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution; and lyophilizing the Ti.sub.3C.sub.2T.sub.x MQD solution for 24 h to 48 h to obtain the TisC2TxMQD nanomaterial.

3. The preparation method according to claim 2, wherein in S2, a preparation process of the aqueous phase solution is as follows: dissolving a polyamine in deionized water, adding the Ti.sub.3C.sub.2T.sub.x MQD nanomaterial, and thoroughly stirring a resulting mixture.

4. The preparation method according to claim 3, wherein in S3, a preparation process of the organic phase solution is as follows: adding a polyacyl chloride to an organic solvent, and thoroughly stirring a resulting mixture.

5. The preparation method according to claim 4, wherein S4 comprises: immersing the UF base membrane in the aqueous phase solution for 2 min to 20 min, and removing the aqueous phase solution from the surface of the UF base membrane through blow-drying with an air knife; immersing the UF base membrane in the organic phase solution for 2 s to 200 s to allow formation of the active layer through the interfacial polymerization reaction; and placing the composite membrane vertically for 50 s to 100 s, followed by subjecting the composite membrane to the heat treatment for 8 min to 20 min in an oven at 40? C. to 90? C. to promote the interfacial polymerization reaction.

6. The preparation method according to claim 2, wherein in S11, a mass percentage concentration of the HF solution is 30% to 50%.

7. The preparation method according to claim 6, wherein in S1, the Ti.sub.3C.sub.2T.sub.x MXene material powder has a particle size of 2 nm to 50 nm, and the Ti.sub.3C.sub.2T.sub.x MQD nanomaterial has a thickness of 1 nm to 20 nm.

8. The preparation method according to claim 7, wherein in S2, a polyamine is at least one selected from the group consisting of m-phenylenediamine (MPD), o-phenylenediamine (OPD), p-phenylenediamine (PPD), m-xylylenediamine (MXD), N,N-dimethylphenylenediamine, and 4-methyl-m-phenylenediamine; a mass percentage concentration of the polyamine is 0.1% to 5%, and a mass percentage concentration of the Ti.sub.3C.sub.2T.sub.x MQD nanomaterial is 0.001% to 0.1%.

9. The preparation method according to claim 4, wherein in S3, the polyacyl chloride is at least one selected from the group consisting of 1,3,5-benzenetricarbonyl trichloride, phthaloyl chloride, isophthaloyl chloride (IPC), 1,3,5-cyclohexanetricarbonyl chloride, and methyl m-phenylene diisocyanate; and a mass percentage concentration of the polyacyl chloride is 0.01% to 2.5%.

10. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 1.

11. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 2.

12. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 3.

13. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 4.

14. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 5.

15. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 6.

16. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 7.

17. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 8.

18. A Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane prepared by the preparation method according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1(a) is a scanning electron microscopy (SEM) image of a surface of the RO composite membrane prepared in Comparative Example 1 of the present disclosure, FIG. 1(b) is an SEM image of a surface of the RO composite membrane prepared in Comparative Example 2 of the present disclosure, and FIG. 1(c) is an SEM image of a surface of the RO composite membrane prepared in Example 3 of the present disclosure;

[0028] FIG. 2(a) is an SEM image of a cross-section of the RO composite membrane prepared in Comparative Example 1 of the present disclosure, FIG. 2(b) is an SEM image of a cross-section of the RO composite membrane prepared in Comparative Example 2 of the present disclosure, and FIG. 2(c) is an SEM image of a cross-section of the RO composite membrane prepared in Example 3 of the present disclosure; and

[0029] FIG. 3 shows a photoluminescence spectrum of the Ti.sub.3C.sub.2T.sub.x MQD obtained in step 2 in Example 1 of the present disclosure under excitation at 340 nm to 500 nm.

DETAILED DESCRIPTION

[0030] In order to make the objective, content, and advantages of the present disclosure clear, specific implementations of the present disclosure will be further described in detail below with reference to the accompanying drawings and examples.

EXAMPLE 1

[0031] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0032] (1) 10.0 g of a Ti.sub.3AlC.sub.2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0033] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C. was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti.sub.3C.sub.2T.sub.x MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder. Photoluminescence spectrum of the Ti.sub.3C.sub.2T.sub.x MQD under excitation at 340 nm to 500 nm is shown in FIG. 3.

[0034] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.001% in an MPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution, then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0035] (4) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C. to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane.

[0036] The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. A specific test process was as follows: water flux and salt rejection of the composite membrane when treating a 2,000 ppm NaCl solution as a feed at a temperature of 25?0.1? C., a flow rate of 0.19 m/s, and a pressure of 225 psi (1.55 MPa) were tested. The water flux is defined as Q =J/(A.Math.t), where J represents a permeated water amount (L), Q represents water flux (L/m2.h), A represents an effective membrane area of an RO membrane (m2), and t represents a time (h). The salt rejection is defined as R=(C.sub.p-C.sub.f)/C.sub.p?100%, where C.sub.p represents a concentration of NaCl in an original solution and C.sub.f represents a concentration of NaCl in a permeate solution. The anti-biological fouling performance of the composite PA RO membrane was tested with an Escherichia coli (E. coli) cell dilution as a contaminant. The composite PA RO membrane was placed in an E. coli cell solution with a concentration of 1.7?10.sup.7/mL and incubated in an incubator at 30? C. to allow soaking under ultraviolet (UV) light for 4 h, and the soaking operation was conducted for 1 d, 2 d, and 3 d; and after the soaking every day, a contaminated composite PA RO membrane was used to treat a 2,000 ppm NaCl solution as a feed, and corresponding water fluxes Q.sub.d1, Q.sub.d2, and Q.sub.d3 were determined. The anti-biological fouling performance of the composite PA RO membrane was measured by a decrease in water flux performance. The feed was replaced by a mixed aqueous solution of NaCl and BSA (in which a concentration of NaCl was 2,000 ppm and a concentration of BSA was 1,000 ppm), and the anti-organic fouling performance of the composite PA RO membrane was tested by calculating a recovery rate of relative water flux. A 2,000 ppm NaCl solution alone was used as a feed to test the separation performance of the composite PA RO membrane for 6 h under a pressure of 1.5 MPa, and a corresponding water flux was determined and denoted as Q.sub.0; then a BSA-containing mixed solution was used a feed to test the separation performance of the composite PA RO membrane for 6 h under the same conditions, and a corresponding water flux was determined and denoted as Q.sub.t; and then the composite PA RO membrane was thoroughly cleaned with deionized water for 0.5 h. The above test process was set as a cycle, and three cycles were conducted in total; and then a recovery rate of relative water flux was calculated as follows: Qr=Q.sub.t/Q.sub.0?100%.

EXAMPLE 2

[0037] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0038] (1) 10.0 g of a Ti.sub.3AlC.sub.2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0039] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C. was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti.sub.3C.sub.2T.sub.x MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder.

[0040] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.005% in an MPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution , then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0041] (4) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C.to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1.

EXAMPLE 3

[0042] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0043] (1) 10.0 g of a TisAIC2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0044] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C. was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti3C2 Tx MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder.

[0045] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.010% in an MPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution , then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0046] (4) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C. to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1. An SEM image of a surface of the RO composite membrane prepared in Example 3 is shown in FIG. 1(c), and an SEM image of a cross-section of the RO composite membrane is shown in FIG. 2(c).

[0047] EXAMPLE 4

[0048] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0049] (1) 10.0 g of a Ti.sub.3AlC.sub.2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0050] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C. was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti.sub.3C.sub.2T.sub.x MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder.

[0051] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.050% in an MPD solution with a mass concentration of 3.0% to obtain an aqueous phase solution , then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0052] (4) The second UF base membrane was soaked in a 1.3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C. to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1.

EXAMPLE 5

[0053] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0054] (1) 10.0 g of a Ti3AlC2 powder was added to an HF solution with a concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0055] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C.was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti.sub.3C.sub.2T.sub.x MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder.

[0056] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.10% in an MPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution , then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0057] (4) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C. to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1.

Example 6

[0058] A preparation method of a Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane was provided, specifically including the following steps:

[0059] (1) 10.0 g of a Ti.sub.3AlC.sub.2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at ?90? C. for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0060] (2) 5.0 g of the Ti.sub.3C.sub.2T.sub.x MXene material powder obtained in step (1) was added to a PTFE beaker, 20 mL of liquid nitrogen was poured into the beaker, and the beaker was placed at room temperature for 5 min; 30 mL of deionized water at 95? C. was added to the beaker, a reaction was conducted for 4 min, and a resulting reaction mixture was stirred at room temperature for 24 h and then filtered through a filter membrane with a pore size of 220 nm; and a resulting filtrate was centrifuged at 10,000 r/min for 20 min to obtain a Ti.sub.3C.sub.2T.sub.x MQD solution, and the Ti.sub.3C.sub.2T.sub.x MQD solution was lyophilized for 48 h to obtain a Ti.sub.3C.sub.2T.sub.x MQD nanomaterial powder.

[0061] (3) The powder obtained in step (2) was dissolved at a mass concentration of 0.010% in an OPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution, then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0062] (4) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C.to further promote the interfacial polymerization to obtain the Ti.sub.3C.sub.2T.sub.x MQD-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1.

COMPARATIVE EXAMPLE 1

[0063] (1) An MPD aqueous solution with a mass concentration of 3.0% was prepared, then 100 mL of the MPD aqueous solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the excess MPD aqueous solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0064] (2) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C.to further promote the interfacial polymerization to obtain a PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1. An SEM image of a surface of the RO composite membrane prepared in Comparative Example 1 is shown in FIG. 1(a), and an SEM image of a cross-section of the RO composite membrane is shown in FIG. 2(a).

COMPARATIVE EXAMPLE 2

[0065] (1) 10.0 g of a Ti3AlC2 powder was added to an HF solution with a mass concentration of 40%, and a resulting mixture was stirred for 72 h at 35? C. to allow etching to obtain an etched powder; the etched powder was washed repeatedly with deionized water and absolute ethanol 4 times until a pH of a resulting washing solution was 6.8; and the resulting washing solution was lyophilized and then vacuum-dried at -90?C for 24 h to obtain a Ti.sub.3C.sub.2T.sub.x MXene material powder.

[0066] (2) The powder obtained in step (1) was dissolved at a mass concentration of 0.010% in an MPD aqueous solution with a mass concentration of 3.0% to obtain an aqueous phase solution, then 100 mL of the aqueous phase solution was poured onto a surface of a first UF base membrane to allow soaking for 5 min, and then the aqueous phase solution on the surface of the first UF base membrane was removed through blow-drying with an air knife, to obtain a second UF base membrane.

[0067] (3) The second UF base membrane was soaked in a 1,3,5-benzenetricarbonyl trichloride organic phase solution with a mass percentage concentration of 0.15% for 60 s to allow interfacial polymerization to form an active layer; and a composite membrane obtained after the interfacial polymerization was placed vertically for 60 s, and then subjected to a heat treatment for 8 min in an oven at 90? C. to further promote the interfacial polymerization to obtain a Ti.sub.3C.sub.2T.sub.x MXene-modified PA RO membrane. The prepared sample was subjected to SEM analysis, and tested for water flux performance, salt retention performance, and anti-fouling performance. Specific test processes were consistent with those in Example 1. An SEM image of a surface of the RO composite membrane prepared in Comparative Example 2 is shown in FIG. 1(b), and an SEM image of a cross-section of the RO composite membrane is shown in FIG. 2(b).

[0068] Experimental results:

[0069] 1. The composite PA RO membranes prepared in Examples 1 to 6 and Comparative Examples 1 and 2 each were tested by the above methods for the water flux, retention rate, and anti-fouling performance, and test results were as follows:

TABLE-US-00001 TABLE 1 Water fluxes, retention rates, and anti-fouling performance of different composite PA RO membranes Water Salt flux rejection Q.sub.d1 Q.sub.d2 Q.sub.d3 Q.sub.r No. (LMH) (%) (LMH) (LMH) (LMH) (%) Example 1 57.3 99.0 50.6 43.5 37.6 95.2 Example 2 63.5 98.7 56.8 47.7 41.5 94.1 Example 3 65.3 98.5 58.4 49.4 42.3 93.2 Example 4 68.6 98.0 60.0 53.4 46.4 92.5 Example 5 72.3 90.7 65.3 56.3 48.3 92.3 Example 6 62.8 98.3 57.3 50.2 41.5 92.8 Comparative 40.0 98.3 33.6 27.5 23.8 91.0 Example 1 Comparative 32.5 99.2 23.5 18.3 15.0 75.5 Example 2

[0070] It can be seen from the data in the table that water fluxes of the composite membranes in Examples 1 to 6 all are significantly improved compared with water fluxes of the ordinary RO membranes in Comparative Examples 1 and 2 (32.5 LMH), while salt rejections of the composite membranes in the examples are not compromised significantly; and with the gradual increase of a concentration of the MQD, the water flux of the composite membrane increases gradually, but when the concentration of the MQD is higher than a specified value (example 5), the salt rejection of the composite membrane begins to decrease. It can be seen from the anti-fouling performance that both the anti-biological fouling performance and the anti-organic fouling performance of the composite membrane have been improved to some extent. Therefore, the composite PA RO membrane prepared by the preparation method provided in the present disclosure has a high water flux and excellent anti-fouling performance. In addition, the preparation method is simple, and has promising industrial application prospects.

[0071] According to the above-mentioned technical solutions, the present disclosure has the following distinctive features:

[0072] (1) In the present disclosure, a Ti.sub.3C.sub.2T.sub.x MQD is prepared by a simple low-temperature micro-explosion method. A principle of the low-temperature micro-explosion method is as follows: Based on an accordion-like microstructure of a Ti.sub.3C.sub.2T.sub.x MXene material, liquid nitrogen is added to allow intercalation, and then high-temperature deionized water is added to provide a temperature difference, such that liquid nitrogen expands rapidly among layers to produce a micro-explosion reaction. Groups on a surface of the Ti.sub.3C.sub.2T.sub.x MQD successfully prepared by this method can easily form hydrogen bonds with water, and thus the Ti.sub.3C.sub.2T.sub.x MQD has high hydrophilicity and can be well dispersed in water without stirring and an ultrasonic treatment.

[0073] (2) In the present disclosure, the Ti.sub.3C.sub.2T.sub.x MQD is introduced into an aqueous solution for interfacial polymerization, and then the interfacial polymerization is conducted to form a PA layer of an RO membrane, which improves the water flux and anti-fouling performance of the RO membrane while providing a new solution for further improving the dispersion of the Ti.sub.3C.sub.2T.sub.x MXene nanomaterial. In addition, the present disclosure further develops use of the Ti.sub.3C.sub.2T.sub.x MXene nanomaterial as a novel additive in improvement of performance of a PA RO membrane.

[0074] The above are preferred implementations of the present disclosure, and it should be noted that those of ordinary skill in the art can make various improvements and modifications without departing from the technical principles of the present disclosure. These improvements and modifications should be regarded as falling within the protection scope of the present disclosure.