CN-121103161-B - Preparation of COF-polyamide hybrid nanofiltration membrane and wastewater treatment application

CN121103161BCN 121103161 BCN121103161 BCN 121103161BCN-121103161-B

Abstract

The invention discloses a preparation method of a COF-polyamide hybrid nanofiltration membrane and an application of wastewater treatment, and belongs to the technical field of water treatment separation membranes. The preparation method of the COF-polyamide hybrid nanofiltration membrane comprises the steps of 1) synthesizing a COF layer on a Polyacrylonitrile (PAN) substrate by an in-situ growth method, and 2) introducing trimesoyl chloride (TMC) and piperazine (PIP) on the COF/PAN substrate, and synthesizing the COF-polyamide hybrid nanofiltration membrane on the surface of the COF layer by an interfacial polymerization process (IP). The COF-polyamide hybrid nanofiltration membrane prepared by the invention contains electronegative functional groups carboxyl, and the protonation of the electronegative functional groups carboxyl improves the density of negative charges on the surface of the membrane, so that the southward effect of the nanofiltration membrane is enhanced, and the high-efficiency interception of divalent anions is realized. In addition, the synthesis method has simple operation, simple working procedures and low cost, is suitable for large-scale preparation and use, and has good practical value.

Inventors

WU MENGYUAN
HAO RUNLONG
HE WEI
MA JING
CHENG ANQI
WEI MAOYU

Assignees

华北电力大学（保定）

Dates

Publication Date: 20260512
Application Date: 20250908

Claims (4)

1. The application of the COF-polyamide hybrid nanofiltration membrane in interception of divalent anions in desulfurization wastewater is characterized in that the preparation steps of the COF-polyamide hybrid nanofiltration membrane are as follows: Placing a PAN substrate in a mixed solution formed by a water phase and an organic phase, adding a catalyst into the mixed solution to react to obtain a COF/PAN film, sequentially placing the COF/PAN film in a piperazine solution and a trimesoyl chloride solution to soak, taking out the piperazine solution and taking out the trimesoyl chloride solution to perform polymerization reaction to obtain the COF-polyamide hybrid nanofiltration membrane; the solute in the aqueous phase is 2, 5-diaminobenzoic acid, and the solute in the organic phase comprises 2,4, 6-trimethylphloroglucinol; The catalyst comprises acetic acid; The concentration of the aqueous phase is 2-15 mmol/L, the concentration of the organic phase is 2-10 mmol/L, and the molar ratio of the aqueous phase monomer to the organic phase monomer in the mixed solution is 3:2; the reaction temperature is 40-80 ℃ and the reaction time is 12-60 hours; The temperature of the polymerization reaction is 40-80 ℃ and the time is 5-15 min.
2. The use according to claim 1, wherein the piperazine solution is an aqueous piperazine solution, and the piperazine solution has a concentration of 0.05-0.25 wt%.
3. The application of claim 1, wherein the trimesoyl chloride solution is an n-heptane solution of trimesoyl chloride, and the concentration of the trimesoyl chloride solution is 0.05-0.25 wt%.
4. The method according to claim 1, wherein the immersing comprises immersing in piperazine solution for 5-15 min, taking out the surface water, and immersing in trimesoyl chloride solution for 0.5-2.5 min.

Description

Preparation of COF-polyamide hybrid nanofiltration membrane and wastewater treatment application Technical Field The invention belongs to the technical field of water treatment separation membranes, and particularly relates to a preparation method of a COF-polyamide hybrid nanofiltration membrane and an application of wastewater treatment. Background The membrane separation technology is used as a novel efficient fluid separation technology, has the advantages of good separation selectivity, high separation precision, no phase change or chemical change, low energy consumption, simple operation, small occupied area and the like, is widely concerned in the separation technology field, and plays a great role in sea water desalination and industrial wastewater purification and water crisis alleviation. The Nanofiltration (NF) membrane is between reverse osmosis and ultrafiltration, can cut off small molecules with molecular weight of 200-1000 Da, and combines the influences of size screening, dielectric repulsion and Donnan effect by a separation mechanism, so that the Nanofiltration (NF) membrane has great application potential in monovalent/divalent ion selective separation, and a high-performance membrane material is a key for realizing efficient separation of the membrane. Covalent organic framework materials (COFs) are emerging crystalline porous polymeric nanomaterials composed of organic molecules connected by covalent bonds, and are widely applied to preparation and separation of membranes in view of unique characteristics of COFs, such as abundant nanopore structures, ordered nanochannels, regular network structures, excellent stability and the like. However, the development of COF films in nanofiltration is still in the primary stage, and the application of COF films in desalination has two major challenges that the inherent pore size is too large to effectively separate small molecules, and low temperature reaction results in poor crystallinity and disordered structure of the COF film. Therefore, it is important to improve the pore diameter of the COF film and to solve the problem of poor film forming property. Based on this, the present invention has been proposed. Disclosure of Invention The invention aims to provide a preparation method of a COF-polyamide hybrid nanofiltration membrane and an application of wastewater treatment, so as to solve the problems in the prior art, firstly, the invention adopts an in-situ growth method to synthesize a COF layer with different hydrophilic groups on a PAN substrate, the functional groups can form hydrogen bond or electrostatic attraction with PIP, so that the diffusion is blocked in the enrichment of monomers in the COF layer and the interfacial polymerization, and the instability of diffusion driving in the interfacial polymerization process is caused, thereby regulating and controlling the aperture and structure of the COF-polyamide. The prepared membranes show excellent retention properties for divalent anions thanks to the Donnan effect (Donnan effect) and enhancement of pore size tunability (pore size shrinking from more than 1nm of COF membrane to 0.43nm of hybrid membrane). In order to achieve the above object, the present invention provides the following solutions: the invention provides a preparation method of a COF-polyamide hybrid nanofiltration membrane, which comprises the following steps: placing a PAN (polyacrylonitrile) substrate into a mixed solution consisting of a water phase and an organic phase, adding a catalyst into the mixed solution, and reacting to obtain a COF/PAN film; Sequentially soaking a COF/PAN film in a piperazine (PIP) solution and a trimesoyl chloride (TMC) solution, and taking out to perform polymerization reaction to obtain the COF-polyamide hybrid nanofiltration membrane; the solute in the aqueous phase is 2, 5-diaminobenzoic acid (Pa-COOH), and the solute in the organic phase comprises 2,4, 6-trimethylphloroglucinol (Tp). Further, the PAN substrate preferably has a molecular weight cut-off of 10kw Da, and any substrate PES, PSU, PVDF, PI meeting this molecular weight cut-off requirement can be used for the preparation of nanofiltration membranes according to the invention. Preferably, the catalyst comprises acetic acid. Further, the concentration of the acetic acid was 36wt%. Preferably, the concentration of the water phase is 2-15 mmol/L, the concentration of the organic phase is 2-10 mmol/L, and the molar ratio of the water phase to the organic phase in the mixed solution is 3:2. Preferably, the reaction temperature is 40-80 ℃ and the reaction time is 12-60 hours. Further, the reaction further comprises the steps of cleaning and drying, and specifically comprises the steps of cleaning with water, 1, 4-dioxane and absolute ethyl alcohol in sequence, and then drying for 12 hours at 60 ℃. Preferably, the piperazine solution is an aqueous solution of piperazine, and the concentration of the piperazine solution is 0.05-0