CN-121988194-A - Symmetrical polyether sulfone flat membrane and preparation method thereof

Abstract

The invention discloses a symmetrical polyether sulfone flat membrane and a preparation method thereof, and belongs to the technical field of membrane separation. The preparation method of the flat membrane comprises the following steps of mixing 15-30 parts of polyethersulfone, 2-10 parts of polyvinylpyrrolidone and 60-80 parts of cyclic lactam solvent according to a proportion, melting at 130-160 ℃, casting to form a membrane, cooling, solidifying, extracting with hot water, and drying to obtain the symmetrical polyether sulfone flat membrane. According to the invention, through the melting and solidification processes of the cyclic amide, the dissolution and precipitation of the polyethersulfone material into a film are realized. The invention adopts an organic solvent-free system containing the cyclic lactam solvent, has no organic solvent in the whole process, has zero VOC emission and is environment-friendly. The prepared separation membrane has a complete sponge-like homogeneous structure, uniform pore diameter, no finger-like pores, good pressure resistance, backwash resistance and high flux performance. Compared with the traditional thermally induced phase separation method, the method has lower operation temperature and obviously reduces the energy consumption in the preparation process.

Inventors

• TIAN LI
• CHEN LINCHANG
• YANG FANG
• WANG CHAOHUI
• LIU FEI

Assignees

• 南京久盈膜科技有限公司

Dates

Publication Date

20260508

Application Date

20260318

Claims (5)

1. 1. The preparation method of the symmetrical polyether sulfone flat membrane is characterized by comprising the following steps of: S1, proportioning and mixing, namely uniformly mixing polyether sulfone, polyvinylpyrrolidone and a cyclic lactam solvent according to a proportion; s2, melting and dissolving, namely stirring and melting the mixture to a homogeneous state at a certain temperature; s3, vacuum defoaming, namely performing vacuum defoaming treatment on the homogeneous molten liquid for 20-40 min; S4, casting to form a film, namely casting the defoamed homogeneous molten liquid into an initial film at a certain temperature; S5, cooling and solidifying, namely cooling and solidifying the initial film; And S6, hot water extraction, namely, extracting and eluting the initial film after cooling and solidification in hot water at 50-90 ℃ and drying to obtain the polyether sulfone flat plate film with the symmetrical structure.
2. 2. The preparation method of the symmetrical polyether sulfone flat membrane according to claim 1, wherein the proportion in S1 is 15-30 parts of polyether sulfone, 2-10 parts of polyvinylpyrrolidone and 60-80 parts of cyclic lactam solvent.
3. 3. The method for preparing a symmetrical polyethersulfone flat membrane according to claim 1, wherein the polyvinylpyrrolidone is one or more selected from K15, K30, K60 and K90.
4. 4. The method for preparing a symmetrical polyethersulfone sheet membrane according to claim 1, wherein the cyclic lactam is selected from cyclic amides having a melting point of 50-150 ℃.
5. 5. A symmetrical polyethersulfone sheet membrane prepared by a process according to any one of claims 1 to 5. The prepared flat membrane has a symmetrical structure, the cross section of the flat membrane is of a continuous sponge-like symmetrical structure, and the flat membrane has no finger holes, macropores, compaction layers and layering.

Description

Symmetrical polyether sulfone flat membrane and preparation method thereof Technical Field The invention relates to the field of membrane separation materials, in particular to a symmetrical polyether sulfone flat membrane and a preparation method thereof. Background Polyethersulfone (PES) membranes are widely used in water treatment, bioseparation and other fields due to their excellent chemical stability, thermal stability and mechanical strength. At present, the preparation of the polyethersulfone membrane mainly adopts a phase inversion method, which comprises non-solvent induced phase separation (NIPS), thermally Induced Phase Separation (TIPS) and other processes. In the prior art, chinese patent CN116726724A discloses a preparation method of a high-flux polyethersulfone flat membrane for bacterial filtration, which is used for obtaining the flat membrane through multiphase induced phase inversion, but the membrane prepared by the method has a highly asymmetric structure. Chinese patent CN118831461B discloses a polyethersulfone membrane with low protein adsorption function, which adopts the formulation of polyethersulfone, amphiphilic copolymer, pore-forming agent, non-solvent and solvent, and prepares hollow fiber membrane by RTIPS method. Chinese patent CN115245744B discloses a high strength polyethersulfone microporous membrane using carbonate acrylate or valerolactone as solvent. The organic solvent is used in the film-making process, so that a large amount of organic wastewater and environmental pollution are generated. The prior art has the following problems that 1. The traditional PES membrane is mainly prepared by adopting organic solvents such as Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) and the like, and the solvents have high volatility, high toxicity and high recovery cost and pollute the environment. 2. The traditional Thermal Induced Phase Separation (TIPS) process lacks a green melting solvent system which can simultaneously meet the requirements of high-temperature melting and dissolving PES, cooling and solidifying to form a film, can be completely eluted by hot water and has uniform and symmetrical structure. 3. The traditional thermal induced phase method needs to be melted at a high temperature of 280-320 ℃, has high energy consumption, needs to be matched with a high boiling point diluent, otherwise, is difficult to prepare an ideal symmetrical structure film product. Therefore, development of a new technical scheme which is environment-friendly, low in energy consumption and capable of preparing a symmetrical polyethersulfone flat membrane is needed. Disclosure of Invention In order to solve the technical problems, the invention provides a symmetrical polyether sulfone flat membrane and a preparation method thereof, and provides a symmetrical polyether sulfone flat membrane which is prepared by adopting an organic solvent-free system and has uniform upper and lower apertures, so that the environment-friendly effect is realized, the operation temperature and the energy consumption are reduced, and the production cost is reduced in the membrane preparation process. In order to solve the technical problems, the invention adopts the technical scheme that the preparation method of the symmetrical polyether sulfone flat membrane comprises the following steps: S1, proportioning and mixing, namely uniformly mixing polyether sulfone, polyvinylpyrrolidone and a cyclic lactam solvent according to a proportion; And S2, melting and dissolving, namely stirring and melting the mixture to a homogeneous state at the temperature of 130-160 ℃, wherein in the step, the cyclic lactam is firstly dissolved into liquid at the temperature, and then the polyethersulfone solid is dissolved to form uniform casting film liquid. Compared with the traditional thermally induced phase separation, the temperature needs to be increased to be higher than the melting point of polyethersulfone, and the operation temperature of the method is obviously reduced; S3, vacuum defoaming, namely performing vacuum defoaming treatment on the homogeneous molten liquid for 20-40 min, and removing bubbles generated in the mixing process to ensure the quality of subsequent film formation; s4, casting to form a film, namely casting the defoamed homogeneous molten liquid into an initial film at 120-150 ℃; and S5, cooling and solidifying, namely cooling and solidifying the initial membrane, wherein in the cooling process, the membrane structure is further stabilized, a continuous spongy porous support structure is formed, and the mechanical strength and flux performance of the membrane are ensured. And S6, hot water extraction, namely extracting and eluting the initial film after cooling and solidification in hot water at 50-90 ℃ and drying to obtain the flat film with the symmetrical structure. Preferably, the proportion of the S1 is 15-30 parts of polyethersulfone, 2-10 parts of polyvinylpyrrolidone and 60-80 parts of cy