CN-122006501-A - Bionic strong acid-resistant nanofiltration membrane and preparation method thereof

CN122006501ACN 122006501 ACN122006501 ACN 122006501ACN-122006501-A

Abstract

The invention relates to a bionic strong acid resistant nanofiltration membrane and a preparation method thereof, wherein the bionic strong acid resistant nanofiltration membrane comprises a porous supporting layer and an active separating layer formed on the surface of the porous supporting layer, and the active separating layer is a polymer network layer formed by interfacial polymerization reaction of aqueous phase solution containing polyamine and oil phase solution containing polybasic acyl chloride on the surface of the porous supporting layer. The water phase solution and/or the oil phase solution also contains a bionic amphiphilic phosphate compound, and the bionic amphiphilic phosphate compound participates in interfacial polymerization reaction through active functional groups in the molecular structure of the bionic amphiphilic phosphate compound, so that the phosphate structure of the bionic amphiphilic phosphate compound is covalently connected into the skeleton of the polymer network layer. The bionic amphiphilic phosphate compound has the beneficial effects that the bionic amphiphilic phosphate compound with a hydrophilic phosphate head, a hydrophobic alkyl tail and a reaction site is synthesized, so that the bionic amphiphilic phosphate compound is spontaneously and orderly arranged at a water/oil interface and participates in interfacial polymerization, the film forming uniformity is improved, the pore size distribution is narrowed, and the intelligent response characteristic of the film is endowed.

Inventors

CHENG XIN
PAN QIAOMING
SHI YINGYING
XIAO LUQI
ZHANG ZHEHUA
QU ZHOU
YANG SHUAI
SONG YIMING

Assignees

杭州水处理技术研究开发中心有限公司

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (10)

1. The bionic strong acid resistant nanofiltration membrane is characterized by comprising a porous supporting layer and an active separating layer formed on the surface of the porous supporting layer; the active separation layer is a polymer network layer formed by interfacial polymerization reaction of aqueous phase solution containing polyamine and oil phase solution containing polybasic acyl chloride on the surface of the porous support layer; The water phase solution and/or the oil phase solution also contains a bionic amphiphilic phosphate compound, and the bionic amphiphilic phosphate compound takes part in interfacial polymerization reaction through an active functional group in a molecular structure of the bionic amphiphilic phosphate compound, so that the phosphate structure of the bionic amphiphilic phosphate compound is covalently connected into the skeleton of the polymer network layer.
2. The biomimetic strong acid resistant nanofiltration membrane of claim 1, wherein the biomimetic amphiphilic phosphate compound has a structural formula of R 1 -O-P(O)(OH)-O-(CH 2 ) n -X; wherein R 1 is a C8-C18 linear or branched alkyl group, n is an integer from 1 to 6; When the bionic amphiphilic phosphate compound is added into an aqueous phase solution, X is amino, secondary amino, tertiary amino or ethanolamine residue; when the bionic amphiphilic phosphate compound is added into an oil phase solution, X is acyl chloride, isocyanate or epoxy.
3. The bionic strong acid resistant nanofiltration membrane of claim 2, wherein the structure is C 12 H 25 -O-P(O)(OH)-O-(CH 2 ) 2 -NH 2 when the bionic amphiphilic phosphate compound is added to an aqueous phase solution, and C 12 H 25 -O-P(O)(OH)-O-(CH 2 ) 2 -NCO when the bionic amphiphilic phosphate compound is added to an oil phase solution.
4. The biomimetic strong acid resistant nanofiltration membrane of claim 1, wherein the active separation layer has a gradient cross-linked structure, the gradient cross-linked structure is a loose inner layer with low cross-linked density and loose structure on the side close to the porous support layer, and a dense surface layer with high cross-linked density and dense structure on the side far from the porous support layer.
5. The biomimetic strong acid resistant nanofiltration membrane according to claim 1, wherein the polyamine is selected from at least one of piperazine, piperazine derivatives, m-phenylenediamine, p-phenylenediamine, N-aminoethylpiperazine, polyethyleneimine; The polybasic acyl chloride is at least one selected from trimesoyl chloride, phthaloyl chloride and terephthaloyl chloride.
6. The bionic strong acid resistant nanofiltration membrane as defined in claim 1, wherein the porous support layer is an acid resistant ultrafiltration membrane, and the material is at least one selected from polysulfone, polyethersulfone, polyvinylidene fluoride, and polytetrafluoroethylene.
7. The preparation method of the bionic strong acid-resistant nanofiltration membrane is characterized by comprising the following steps of: S1, preparing a bionic amphiphilic phosphate compound, namely, reacting C8-C18 alkyl alcohol with phosphorus pentoxide, hydrolyzing to obtain an alkyl phosphate intermediate of R1-O-P (O) (OH) -OH, and reacting the alkyl phosphate intermediate with an excessive compound containing an active functional group in the presence of a condensing agent to obtain a bionic amphiphilic phosphate compound R 1 -O-P(O)(OH)-O-(CH 2 ) n -X suitable for a water phase, wherein R 1 is a linear chain or branched chain alkyl of C8-C18, n is an integer of 1-6, and X is an amino group, a secondary amino group, a tertiary amino group or an ethanolamine residue; s2, dissolving polyamine and the bionic amphiphilic phosphate compound applicable to the water phase into water to prepare an aqueous phase solution, and adopting the aqueous phase solution and the oil phase solution dissolved with polybasic acyl chloride to carry out interfacial polymerization reaction to form at least one polymer network layer on the surface of the porous supporting layer; Or alternatively Dissolving the bionic amphiphilic phosphate compound applicable to the water phase in an organic solvent, reacting with a derivatization reagent, converting active functional groups of the bionic amphiphilic phosphate compound applicable to the water phase into active functional groups capable of reacting with polyamine to obtain a bionic amphiphilic phosphate compound applicable to the oil phase R 1 -O-P(O)(OH)-O-(CH 2 ) n -X, wherein R 1 is a linear chain or branched chain alkyl group of C8-C18, n is an integer of 1-6, X is acyl chloride, isocyanate group or epoxy group; And S3, carrying out post-treatment on the membrane subjected to the interfacial polymerization reaction to obtain the bionic strong acid resistant nanofiltration membrane.
8. The method for preparing the bionic strong acid resistant nanofiltration membrane as claimed in claim 7, wherein, In the step S2, the concentration of the bionic amphiphilic phosphate compound suitable for the water phase in the water phase solution is 0.01-1.0 wt%; The concentration of the bionic amphiphilic phosphate compound suitable for the oil phase in the oil phase solution is 0.01-1.0 wt%.
9. The method for preparing a bionic strong acid resistant nanofiltration membrane as defined in claim 7, wherein in step S2, the interfacial polymerization reaction adopts a step-by-step interfacial polymerization process, comprising: Preparing a first oil phase solution and a second oil phase solution, wherein the concentration of the polybasic acyl chloride in the second oil phase solution is higher than that of the first oil phase solution; The first step of interfacial polymerization, namely contacting the aqueous phase solution with the porous supporting layer, and then contacting the aqueous phase solution with the first oil phase solution to perform a first interfacial polymerization reaction to form a loose inner layer; and the second step of interfacial polymerization, namely, after the first interfacial polymerization, contacting with the second oil phase solution to perform the second interfacial polymerization, and forming a compact surface layer on the loose inner layer.
10. The method for preparing a bionic strong acid resistant nanofiltration membrane as claimed in claim 9, wherein the reaction time of the first interfacial polymerization is 5 s-40 s, and the reaction time of the second interfacial polymerization is 40 s-120 s.

Description

Bionic strong acid-resistant nanofiltration membrane and preparation method thereof Technical Field The invention relates to the technical field of high-performance separation membranes, in particular to a bionic strong acid-resistant nanofiltration membrane and a preparation method thereof. Background The nanofiltration membrane separation technology has been widely used in the fields of water treatment, food processing, chemical separation, etc. because of the advantages of low operating pressure, high selectivity, low energy consumption, etc. Wherein, the polyamide composite nanofiltration membrane becomes the main stream of the current nanofiltration membrane by virtue of the excellent separation performance. However, the separation layer of the conventional polyamide nanofiltration membrane is formed by interfacial polymerization, and its chemical structure contains a large number of amide bonds. In the separation process of the acid amide bond in the strong acid medium, the traditional polyamide nanofiltration membrane is rapidly failed because the acid amide bond is easy to hydrolyze. For this reason, researchers have turned to the development of composite nanofiltration membranes based on polyureas or acid-resistant modified polyamides, and have recently explored new systems of polysulfonamides, poly (triazinyl) amines, polyurethanes, etc. starting from the polymer backbone structure, in order to fundamentally solve the problem of amide bond hydrolysis. At present, the invention patent of publication No. CN113509839B, which adopts pure isocyanate-amine interfacial polymerization system, provides a polyurea which can be formed by taking urea bond as a crosslinking unit. Although urea bond is utilized to improve chemical stability, the reactivity of isocyanate and amine is obviously lower than that of the traditional acyl chloride-amine system, so that the monomer concentration is required to be improved or the reaction time is required to be prolonged to obtain enough crosslinking degree and interception performance, the formed active layer is thicker, the mass transfer resistance is large, the acid permeation flux is generally lower, and the requirement of high-efficiency separation is difficult to meet. The polysulfonamide nanofiltration membrane is another technical path, and the membrane can prepare a positively charged separation layer by utilizing the hydrolytic stability of sulfonamide bonds and through catalyst-assisted secondary polymerization. Studies have shown that its performance remains stable after 30 days of soaking in 25wt% sulfuric acid. However, the rejection rate of divalent ions such as Mg 2+ by polysulfonamide membranes is generally less than 95%, and the permeate flux tends to drop significantly. The polyurethane nanofiltration membrane can prepare an ultrathin selection layer with the thickness of only 10nm by utilizing the reaction of isocyanate and polyphenol through dynamic regulation, and can effectively regulate and control a sub-nano pore canal, and has good acid-resistant stability, but the polyurethane nanofiltration membrane is mainly aimed at screening macromolecular dyes/heavy metal ions, and has no discussion on the high-efficiency interception capability of the polyurethane nanofiltration membrane on micromolecular inorganic salt ions. In order to break through the performance bottleneck of the separation layer material, a new strategy for regulating and controlling the diffusion of monomers and realizing an ultrathin separation layer by introducing an intermediate layer (such as a carbon nano tube, nano cellulose and the like) has also appeared in recent years. Wherein the intermediate layer acts as a "reservoir" to uniformly adsorb and store the aqueous amine monomer, facilitating the formation of a thinner, less defective polyamide separation layer. However, the method requires an additional intermediate layer construction step, increases the process complexity and the production cost, mainly relies on physical adsorption combination between the intermediate layer and the base film and between the intermediate layer and the separation layer, has potential risks of interfacial peeling or performance attenuation under long-term operation, does not participate in the chemical structure forming the final separation layer, and cannot introduce functions such as pH response and the like into the network framework of the film. Another strategy is by post-modification or construction of the composite active layer structure. For example, the invention patent of publication No. CN119548987A further incorporates a polyhydric phenol modifying layer after formation of the polyurea separating layer, and the invention patent of publication No. CN117181027A constructs a polyamide-polyurea composite network using both acid chloride and isocyanate monomers in the oil phase. The method realizes complementation of performances to a certain extent, but has complex process steps, in