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EP-4741047-A1 - USE OF TEMPERATURE-SENSITIVE COMPOSITE MATERIAL IN PREPARATION OF SEPARATION MEMBRANE, AND NANOFILTRATION MEMBRANE AND PREPARATION METHOD

EP4741047A1EP 4741047 A1EP4741047 A1EP 4741047A1EP-4741047-A1

Abstract

The present invention provides an application of a thermoresponsive composite material in the preparation of separation membranes, a nanofiltration membrane, and a preparation method therefor, specifically relating to the technical field of separation membranes. The thermoresponsive composite material comprises a thermoresponsive material and a conductive filler, with a mass ratio of the thermoresponsive material to the conductive filler ranging from 10-30: 1-10. Utilizing the rapid temperature response characteristic of the thermoresponsive material and transmitting this property via the conductive filler to the external environment, the present invention enables timely feedback and adjustment of temperature during the preparation process of separation membranes. This facilitates the preparation of isotropic separation membranes, ensures stability in membrane performance, and improves the quality of separation membrane products.

Inventors

  • CHEN, YILI
  • ZHANG, Qinglei
  • WEN, JIANPING
  • HOU, Qin
  • LI, SUODING
  • LU, Yanbin
  • WANG, ZHEN
  • YANG, Xuexuan

Assignees

  • Beijing Originwater Membrane Technology Co., Ltd.

Dates

Publication Date
20260513
Application Date
20230811

Claims (13)

  1. An application of a thermoresponsive composite material in the preparation of separation membranes, wherein the thermoresponsive composite material comprises a thermoresponsive material and a conductive filler.
  2. The application according to claim 1, characterized in that the mass ratio of the thermosensitive material to the conductive filler ranges from 10-30:1-10; Optionally, the thermosensitive material comprises at least one of polylactic acid, poly(N-isopropylacrylamide), polystyrene, polyurethane, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polycaprolactone, polyethylene oxide, and polyvinyl chloride; Optionally, the conductive filler comprises at least one of polyacetylene and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, poly(p-styrene) and its derivatives, and polyaniline and its derivatives; Optionally, the particle size of the conductive filler is 5 nm-20 nm; Optionally, the average particle size of the conductive filler is 5 nm-20 nm.
  3. The application according to claim 1 or 2, characterized in that the separation membrane comprises microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, pervaporation membranes, or ion exchange membranes.
  4. A nanofiltration membrane, characterized in that it comprises a porous support layer, a thermoresponsive modification layer, and an interfacial polymerization layer stacked sequentially; wherein the thermoresponsive modification layer comprises a thermoresponsive composite material.
  5. The nanofiltration membrane according to claim 4, wherein the thermoresponsive composite material comprises a thermoresponsive material and a conductive filler; Optionally, the mass ratio of the thermoresponsive material to the conductive filler ranges from 10-30:1-10; Optionally, the thermoresponsive material comprises at least one of polylactic acid, poly(N-isopropylacrylamide), polystyrene, polyurethane, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polycaprolactone, polyethylene oxide, and polyvinyl chloride; Optionally, the conductive filler comprises at least one of polyacetylene and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, poly(p-styrene) and its derivatives, and polyaniline and its derivatives; Optionally, the particle size of the conductive filler is 5 nm-20 nm; Optionally, the average particle size of the conductive filler is 5 nm-20 nm.
  6. The nanofiltration membrane according to claim 4 or 5, characterized in that the thickness of the porous support layer is 10 µm-80 µm, the average pore size is 10 nm-100 nm, and the porosity is 20%-70%.
  7. The nanofiltration membrane according to claim 4 or 5, characterized in that the thickness of the porous support layer is 10 µm-50 µm, the average pore size is 10 nm-100 nm, and the porosity is 20%-70%; Optionally, the thickness of the thermoresponsive modification layer is 1 µm-5 µm, the average pore size is 5 nm-50 nm, and the porosity is 10%-50%; Optionally, the thickness of the interfacial polymerization layer is 10 nm-100 nm, the average pore size is 0.5 nm-2 nm, and the porosity is 10%-50%.
  8. A preparation method for the nanofiltration membrane according to any one of claims 4-7, characterized in that the method comprises the following steps: A. Preparing the thermoresponsive composite material into a slurry, coating it onto the porous support layer using a slot die quantitative coating process, and drying it in a first oven to obtain a nanofiltration membrane semi-finished product provided with the thermoresponsive modification layer on the porous support layer; B. Coating an aqueous phase solution onto one side surface of the nanofiltration membrane semi-finished product, removing excess aqueous phase solution from the surface using a nitrogen air knife, then coating an oil phase solution onto the surface of the aqueous phase solution, and placing it into a second oven equipped with an infrared temperature probe; the infrared temperature probe is disposed on the thermoresponsive modification layer and used to measure the temperature of the surface of the thermoresponsive modification layer, and the nanofiltration membrane is obtained after drying.
  9. The preparation method according to claim 8, characterized in that the infrared temperature probe is disposed at least at three points on the width direction of the thermoresponsive modification layer: left, middle, and right; Optionally, in step B, the drying temperature is 30°C-90°C, and the drying time is 40s-120s.
  10. The preparation method according to claim 8 or 9, characterized in that in step A, the slurry comprises the following components by mass percentage: thermosponsive composite material 11%-40%, additives 1%-8%, and the balance being solvent; Optionally, the thermoresponsive composite material comprises a thermoresponsive material and a conductive filler; Optionally, the mass ratio of the thermoresponsive material to the conductive filler ranges from 10-30:1-10.
  11. The preparation method according to any one of claims 7-10, characterized in that in step A, the slurry comprises the following components by mass percentage: thermoresponsive material 10%-30%, conductive filler 1%-10%, additives 1%-3%, and the balance being solvent; Optionally, the additives comprise at least one of ketones, alcohols, mixtures of polyvinyl alcohols with different molecular weights, and mixtures of polyvinylpyrrolidone with different molecular weights; Optionally, the molecular weight of the ketones is 30-98; Optionally, the ketones comprise at least one of n-propanone, isopropanone, acetone, butanone, and cyclohexanone; Optionally, the molecular weight of the alcohols is 32-60; Optionally, the alcohols comprise at least one of methanol, ethanol, isopropanol, and n-propanol; Optionally, the solvent comprises at least one of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide.
  12. The preparation method according to claim 11, characterized in that in step A, the slurry is prepared by first uniformly dispersing the conductive filler in the solvent, then adding the thermoresponsive material and the additives, stirring to achieve uniform mixing, and thereby obtaining the slurry.
  13. The preparation method according to any one of claims 7-12, characterized in that in step A, in the slot die quantitative coating process, the coating speed is 2 m/min-20 m/min, and the coating amount is 10 mL/min-500 mL/min; Optionally, in step A, the drying temperature is 40°C-80°C.

Description

The present invention claims priority from Chinese Patent Application No. 2023108224194, titled "Application of Thermoresponsive Composite Material in the Preparation of Separation Membranes, Nanofiltration Membrane, and Preparation Method Thereof," filed with China National Intellectual Property Administration (CNIPA) on July 5, 2023, the entire contents of which are incorporated herein by reference. Field Of the Invention The present invention relates to the technical field of separation membranes, and particularly to an application of a thermoresponsive composite material in the preparation of separation membranes, a nanofiltration membrane, and a preparation method therefor. Background Art Against the backdrop of resource recovery and sustainable development, membrane technology exhibits significant potential in eco-friendly applications. Owing to advantages such as low energy consumption, easy operation, and scalability, membrane separation technology has rapidly developed over the past few decades. Among these, organic membranes, characterized by excellent mechanical properties, scalable preparation, and relatively low production costs, dominate the separation membrane market. Membrane separation technology has been widely applied across various industries, such as in circulating water systems, seawater desalination, purification processes, clean energy production, and gas separation. Among all methods for preparing separation membranes, interfacial polymerization technology is particularly capable of regulating the size and thickness of thin films with ease. Additionally, the synthesized thin films exhibit uniform pore structures, making it advantageous in applications including adsorption, catalysis, and energy storage. The most significant large-scale application of interfacial polymerization technology lies in the preparation of ultra-thin composite membranes, such as those used in nanofiltration, reverse osmosis, and gas separation. Interfacial polymerization technology refers to a process where two highly reactive monomers are dissolved in two immiscible solvents, respectively, and undergo an irreversible polycondensation reaction at the interface of the two phases. During membrane fabrication, although temperature control measures are implemented at key locations such as the water phase tank and platform area, the temperature control equipment can only regulate the polymerization reaction temperature based on the set temperature within the equipment itself. It cannot accurately capture the actual polymerization temperature of the interfacial polymerization layer. Due to significant temperature fluctuations at the interface caused by factors such as water phase evaporation and external environmental conditions, these temperature changes cannot be precisely fed back to the temperature control equipment. This not only affects desalination efficiency but also compromises performance stability. Additionally, seasonal variations in the actual water/oil phase monomer concentrations on the base membrane surface lead to substantial fluctuations in product performance. The actual temperature during interfacial polymerization influences both the diffusion kinetic rates of the water/oil phases and the initial thermodynamic rates of the reaction, ultimately affecting the crosslinking degree of the polycondensation reaction. Consequently, the permeation flux of the formed interfacial polymerization layer and the impurity rejection rate become uncontrollable. Summary of the Invention The present invention provides an application of a thermoresponsive composite material in the preparation of separation membranes, wherein the thermoresponsive composite material comprises a thermoresponsive material and a conductive filler. Optionally, the thermoresponsive material and the conductive filler have a mass ratio ranging from 10-30:1-10; Optionally, the thermoresponsive material comprises at least one of polylactic acid, poly(N-isopropylacrylamide), polystyrene, polyurethane, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polycaprolactone, polyethylene oxide, and polyvinyl chloride;Optionally, the conductive filler comprises at least one of polyacetylene and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, polystyrene and its derivatives, and polyaniline and its derivatives;Optionally, the conductive filler has a (average) particle size of 5 nm-20 nm;Optionally, the separation membrane includes microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, pervaporation membranes, or ion exchange membranes. The present invention further provides a nanofiltration membrane, comprising a porous support layer, a thermosensitive modification layer, and an interfacial polymerization layer stacked sequentially; wherein the thermosensitive modification layer comprises the thermosensitive composite material. Optionally, the thermosensit