CN-121623603-B - COF nanosphere doped polyamide composite membrane and preparation method and water purification method thereof

Abstract

The invention belongs to the technical field of membrane separation, and particularly relates to a COF nanosphere doped polyamide composite membrane, a preparation method thereof and a water purification method. The preparation method comprises the steps of dropwise adding aqueous phase COF nanosphere dispersion liquid on the surface of a pretreated porous support substrate film to obtain an aqueous phase supported porous support substrate film, wherein the aqueous phase COF nanosphere dispersion liquid is aqueous phase COF nanosphere dispersion liquid obtained by dispersing purified COF nanosphere suspension liquid in piperazine aqueous solution, dropwise adding trimesoyl chloride n-hexane solution on the surface of the aqueous phase supported porous support substrate film, forming a COF nanosphere doped polyamide functional separation layer through interfacial polymerization reaction of piperazine and trimesoyl chloride, and carrying out post-treatment to obtain the COF nanosphere doped polyamide composite film. The composite membrane has high permeation flux and high retention rate and good separation performance.

Inventors

• SHEN LIGUO
• LIU YING
• TANG LIQIU
• ZHU LELE
• JIN GUANHUA
• LI BO

Assignees

• 浙江师范大学

Dates

Publication Date

20260512

Application Date

20260204

Claims (10)

1. 1. The preparation method of the COF nanosphere doped polyamide composite membrane is characterized by comprising the following steps of: Dropwise adding aqueous phase COF nanosphere dispersion liquid on the surface of the pretreated porous support substrate film to obtain an aqueous phase supported porous support substrate film, wherein the aqueous phase COF nanosphere dispersion liquid is aqueous phase COF nanosphere dispersion liquid obtained by dispersing purified COF nanosphere suspension liquid in piperazine aqueous solution; Dripping trimesoyl chloride n-hexane solution on the surface of the water phase supported porous support substrate membrane, and forming a COF nanosphere doped polyamide functional separation layer through interfacial polymerization reaction of piperazine and trimesoyl chloride; post-processing to obtain the COF nanosphere doped polyamide composite membrane; The purified COF nanosphere suspension is a dialysis-treated COF-TAPB-2,3-DHA nanosphere suspension, and the average particle size of the COF nanospheres is 50 nm-100 nm.
2. 2. The process according to claim 1, wherein the aqueous piperazine solution has a concentration of 0.02w/v%, and/or The concentration of the trimesic acid chloride n-hexane solution is 0.15w/v%.
3. 3. The method of claim 1, wherein the concentration of purified COF nanospheres in the aqueous COF nanosphere dispersion is 1.93mg/L, 3.85mg/L, 5.78mg/L, 7.71mg/L, or 9.63mg/L.
4. 4. The preparation method of the purified COF nanosphere suspension according to claim 1, wherein the preparation method comprises the steps of dripping an amine monomer solution into a preactivated aldehyde monomer solution, standing for 7 days at room temperature to form a stable COF-TAPB-2,3-DHA nanosphere suspension, and dialyzing in absolute ethanol for 48 hours by using a dialysis bag with a molecular weight cut-off of 8-14 kDa to obtain the purified COF nanosphere suspension.
5. 5. The method for preparing an amine monomer solution according to claim 4, wherein the method comprises adding ethanol and acetonitrile to 1,3, 5-tris (4-aminophenyl) benzene, and performing ultrasonic treatment for 3 minutes to obtain an amine monomer solution; the ratio of 1,3, 5-tris (4-aminophenyl) benzene to ethanol to acetonitrile was controlled to be 0.06 mmol/20 mL/5 mL in terms of mass to volume ratio.
6. 6. The preparation method of the pre-activated aldehyde monomer solution according to claim 4, wherein the preparation method comprises the steps of adding ethanol and acetonitrile to 2, 3-dihydroxyterephthalaldehyde, carrying out ultrasonic treatment for 3 minutes, adding trifluoroacetic acid to the mixture, and carrying out ultrasonic treatment for 20 minutes to obtain the pre-activated aldehyde monomer solution; The ratio of 2, 3-dihydroxyterephthalaldehyde to ethanol to acetonitrile to trifluoroacetic acid was controlled to be 0.09 mmol/20 mL/5 mL/20. Mu.L in terms of mass to volume ratio.
7. 7. The preparation method of the pretreated porous support substrate film according to claim 1, wherein the preparation method comprises the steps of immersing a polyethersulfone film in deionized water for 2 hours, replacing the deionized water, and continuing the immersion for 24 hours to obtain the pretreated porous support substrate film.
8. 8. The method according to claim 1, wherein the post-treatment comprises removing unreacted trimesoyl chloride by rinsing with a normal hexane solution, heat-treating at 60 ℃ for 5 minutes, and cooling to room temperature.
9. 9. A COF nanosphere doped polyamide composite membrane, characterized in that the COF nanosphere doped polyamide composite membrane is prepared by the preparation method of the COF nanosphere doped polyamide composite membrane according to any one of claims 1 to 8.
10. 10. A water purification method, characterized in that the COF nanosphere doped polyamide composite membrane according to claim 9 or the COF nanosphere doped polyamide composite membrane prepared by the preparation method of the COF nanosphere doped polyamide composite membrane according to any one of claims 1 to 8 is used for water purification.

Description

COF nanosphere doped polyamide composite membrane and preparation method and water purification method thereof Technical Field The invention belongs to the technical field of membrane separation, and particularly relates to a COF nanosphere doped polyamide composite membrane, a preparation method thereof and a water purification method. Background The membrane separation technology has the advantages of simple operation, low energy consumption, high separation efficiency and the like, and is widely applied to the fields of sea water desalination, wastewater treatment and the like. The Polyamide (PA) composite membrane becomes a core material of nanofiltration and reverse osmosis membranes by virtue of excellent chemical stability and higher selectivity, and is widely applied to dye/salt separation, organic pollutant removal and other scenes. The polyamide composite membrane has typical contradictory characteristics of high selectivity and low permeability, and still has a need for solving the problem. Disclosure of Invention The invention aims to provide a COF nanosphere doped polyamide composite membrane, a preparation method thereof and a water purification method, wherein the COF nanosphere doped polyamide composite membrane forms a COF nanosphere doped polyamide functional separation layer on the surface of a porous support substrate membrane through interfacial polymerization reaction, and the hydrophilicity, the aperture and the surface charge of the polyamide separation layer are synergistically improved by introducing the COF nanospheres, so that the water flux of the composite membrane is obviously improved, the rejection rate of sodium sulfate is improved, and chloride ions and sulfate ions can be screened with high precision. The first aspect of the invention provides a preparation method of a COF nanosphere doped polyamide composite membrane, which comprises the following steps of dropwise adding aqueous phase COF nanosphere dispersion on the surface of a pretreated porous support substrate membrane to obtain an aqueous phase loaded porous support substrate membrane, wherein the aqueous phase COF nanosphere dispersion is aqueous phase COF nanosphere dispersion obtained by dispersing purified COF nanosphere suspension in piperazine aqueous solution, dropwise adding trimesoyl chloride n-hexane solution on the surface of the aqueous phase loaded porous support substrate membrane, and forming a COF nanosphere doped polyamide functional separation layer through interfacial polymerization reaction of piperazine and trimesoyl chloride, and carrying out post-treatment to obtain the COF nanosphere doped polyamide composite membrane. The surface of the pretreated porous support substrate film has a hydrophilic and porous structure, and can bear aqueous dispersion liquid through capillary action and surface adsorption force. The aqueous phase COF nanosphere dispersion takes piperazine aqueous solution as a dispersion medium, piperazine is taken as an aqueous phase monomer for interfacial polymerization and can be uniformly distributed on the surface of the porous support substrate film, and on the other hand, the COF nanospheres are taken as functional doping phases, and uniform loading is realized by means of the fluidity of the dispersion and the adsorption effect of the porous support substrate film, so that stable functional sites are provided for the doping of a subsequent polyamide layer. Piperazine and trimesic acid chloride carry out interfacial polymerization reaction, the COF nanospheres which are pre-loaded in the water phase are wrapped in a polyamide network in situ to form a polyamide functional separating layer doped with the COF nanospheres, uniform doping of the COF nanospheres on the polyamide separating layer is realized through the synergistic effect of the water phase loaded COF nanospheres and interfacial polymerization, the performance of the composite membrane is improved due to the pore channel structure and the surface characteristics of the COF nanospheres, the permeation flux, the interception performance and the structural stability of the composite membrane are obviously improved, the permeation flux of water is improved, and the interception capability of pollutants is enhanced. In some embodiments of the invention, the concentration of the aqueous piperazine solution is 0.02w/v%, and/or the concentration of the trimesoyl chloride n-hexane solution is 0.15w/v%. The concentrations of the two solutions are favorable for controlling interfacial polymerization reaction, and the film forming quality and stability of the polyamide functional separation layer doped with the COF nanospheres are improved. In some embodiments of the invention, the concentration of purified COF nanospheres in the aqueous phase COF nanosphere dispersion is 1.93mg/L, 3.85mg/L, 5.78mg/L, 7.71mg/L, or 9.63mg/L. The concentration of the dispersion liquid is beneficial to regulating and controlling the doping