CN-121988190-A - High-performance polyamide nanofiltration membrane and preparation method and application thereof

CN121988190ACN 121988190 ACN121988190 ACN 121988190ACN-121988190-A

Abstract

The invention discloses a high-performance polyamide nanofiltration membrane, a preparation method and application thereof, wherein the polyamide nanofiltration membrane is formed by sequentially coating a polyamine solution and an acyl chloride solution on a single side of an ultrafiltration base membrane, and then constructing a polyamide functional layer on the surface of the ultrafiltration base membrane through a thermal crosslinking reaction; wherein, a zwitterionic surfactant is added into the polyamine solution; according to the nanofiltration membrane, the amphoteric surfactant is introduced into the polyamine solution to regulate and control the interfacial polymerization reaction process, so that the dual improvement of the high-purity water permeability coefficient and the mono/divalent salt ion separation effect is realized, the membrane surface hydrophilicity is good, the electronegativity is weakened, the pore size screening function is depended on, and in the preparation method of the polyamide nanofiltration membrane, the suction filtration operation is replaced by the operation of pouring out the excessive polyamine solution on the surface of the ultrafiltration base membrane, so that the membrane performance is further improved, and the membrane has wide application prospects in the fields of water treatment, material separation and purification and the like.

Inventors

HAO SHUANG
HU YUNXIA
MA DING
WEI MINGJIE
Xiang Tianshuo
ZHAO XIN
GAO JIE

Assignees

天津工业大学
南京工业大学苏州未来膜技术创新中心

Dates

Publication Date: 20260508
Application Date: 20260318

Claims (10)

1. A preparation method of a high-performance polyamide nanofiltration membrane is characterized in that a polyamide functional layer is constructed on the surface of an ultrafiltration base membrane through a thermal crosslinking reaction after a polyamine solution and an acyl chloride solution are coated on a single side surface of the ultrafiltration base membrane in sequence, wherein a zwitterionic surfactant is added into the polyamine solution.
2. The method for preparing the high-performance polyamide nanofiltration membrane according to claim 1, wherein the polyamine solution is a polyamine aqueous solution with a mass fraction of 0.05-wt-0.5-wt%, and wherein the addition amount of the zwitterionic surfactant in the polyamine aqueous solution is 0.02-wt-0.1-wt%.
3. The preparation method of the high-performance polyamide nanofiltration membrane as claimed in claim 2, wherein the polyamine is selected from piperazine, dimethyl piperazine and polyethyleneimine, the zwitterionic surfactant contains cationic and anionic groups in the structure, the cationic groups are selected from nitrogen-containing basic groups including at least one of amine groups, quaternary ammonium groups and imidazole groups, the anionic groups are selected from acidic groups including at least one of carboxyl groups, sulfate groups and sulfonic groups, and the carbon number of the zwitterionic surfactant is 10-25.
4. The method for preparing a high performance polyamide nanofiltration membrane according to claim 1, wherein the ultrafiltration base membrane is selected from the group consisting of polyethersulfone membrane, polysulfone membrane, cellulose acetate membrane, polyvinylidene fluoride membrane, polysulfone membrane and polyacrylonitrile membrane, and has a pore size in the range of 5 nm to 200 nm.
5. The method for preparing the high-performance polyamide nanofiltration membrane according to claim 1, wherein the acid chloride solution is an organic acid chloride monomer solution with a mass fraction of 0.1 wt-0.5 wt%.
6. The method for preparing the high-performance polyamide nanofiltration membrane as claimed in claim 5, wherein the acyl chloride monomer is selected from trimesoyl chloride, benzoyl chloride and dibenzoyl chloride, and the organic solvent for preparing the organic solution is selected from n-hexane, isoparaffin, n-nonane and n-decane.
7. The method for preparing a high performance polyamide nanofiltration membrane according to claim 1, wherein the ultrafiltration base membrane is placed in a suction filtration funnel, the polyamine solution is coated on one side of the ultrafiltration base membrane and kept stand for 0.2 min-1 min, and after the excessive polyamine solution is removed by suction filtration, the acid chloride solution is coated and kept stand for 0.5 min-2 min.
8. The method for preparing a high performance polyamide nanofiltration membrane according to claim 1, wherein the thermal crosslinking reaction temperature is 30 ℃ to 80 ℃ and the thermal crosslinking time is 3 min to 10 min.
9. A high-performance polyamide nanofiltration membrane prepared by the method for preparing a high-performance polyamide nanofiltration membrane according to any one of claims 1 to 8.
10. Use of a high performance polyamide nanofiltration membrane as claimed in claim 9 for the efficient separation of divalent ions from monovalent ions in solution.

Description

High-performance polyamide nanofiltration membrane and preparation method and application thereof Technical Field The invention relates to the technical field of functional membrane materials, in particular to a high-performance polyamide nanofiltration membrane and a preparation method and application thereof. Background Nanofiltration is used as a high-efficiency pressure-driven membrane separation technology, and is widely applied to the fields of wastewater treatment, petrochemical industry, pharmaceutical industry and the like due to the advantages of moderate operating pressure, high separation selectivity and the like. At present, commercial nanofiltration membranes are mostly prepared by adopting an interfacial polymerization method, and a polyamide separation layer is formed by the rapid reaction of amine monomers and acyl chloride monomers at an interface. However, the reaction process is extremely rapid, the diffusion behavior of the amine monomer at the interface is difficult to control accurately, the pore size distribution of the formed polyamide layer is uneven, the precise screening capability of the membrane on monovalent/divalent ions is restricted, and the membrane is also faced with a 'trade-off' effect which is difficult to reconcile between the improvement of the water permeation flux and the maintenance of the high retention rate. To optimize the interfacial polymerization process, researchers have attempted to introduce surfactants for modulating interfacial properties. The existing researches mostly adopt anionic or cationic surfactants, and the separation performance of the membrane is optimized to a certain extent by improving the spreadability of the water phase on the surface of the substrate and adjusting the interfacial tension. However, after such surfactant modification, the surface of the membrane mostly has specific charge characteristics, and it is difficult to simultaneously achieve efficient separation of ions of different electrical properties. How to construct nanofiltration membranes capable of meeting the separation requirements of different electric ions while strengthening the water flux is still a key technical problem to be solved in the current research field. Based on the technical background, the invention provides that the amphoteric surfactant is introduced as an interfacial polymerization modifier. The surfactant carries positive and negative charge groups at the same time, and can effectively regulate and control the diffusion behavior of amine monomers in a water phase, namely, reduce interfacial tension and control the release rate of the monomers, so that a polyamide separation layer with thinner and higher crosslinking degree is generated. This structure imparts excellent hydrophilicity and reduced electronegativity to the membrane surface, making ion separation more dependent on pore size sieving. Based on the mechanism, the invention is hopeful to realize the efficient screening of ions with different electrical properties while improving the water permeation flux, and provides a new path for breaking through the traditional 'trade-off' effect and preparing the high-performance nanofiltration membrane. Disclosure of Invention The invention aims to provide a high-performance polyamide nanofiltration membrane with high pure water permeability coefficient and divalent ion retention rate, which solves the technical problems. The invention also aims to provide a preparation method of the high-performance polyamide nanofiltration membrane. Another object of the present invention is to provide the use of the high performance polyamide nanofiltration membrane. For this purpose, the technical scheme of the invention is as follows: A preparation method of a high-performance polyamide nanofiltration membrane comprises the steps of sequentially coating a polyamine solution and an acyl chloride solution on one side of an ultrafiltration base membrane, and then constructing a polyamide functional layer on the surface of the ultrafiltration base membrane through a thermal crosslinking reaction, wherein a zwitterionic surfactant is added into the polyamine solution. In the improved preparation process of the polyamide nanofiltration membrane, the amphoteric ion surfactant added in the polyamine solution has the function of adjusting the diffusion behavior of reactants, particularly plays a role in promoting the migration and diffusion of the polyamine to the solution reaction interface at the membrane surface in the process of making the polyamine solution and the acyl chloride solution in interface contact and react to form polyamide, realizes the acceleration molding of the polyamide composite membrane, and finally obtains a polyamide functional thin layer with proper pore diameter after the thermal crosslinking reaction. In addition, the zwitterionic characteristic of the amphoteric surfactant also has the effects of adjusting the water-oil two-phase interface p