Cesium adsorption film and preparation method and application thereof

Abstract

The invention discloses a cesium adsorption film and a preparation method and application thereof, and belongs to the technical field of adsorption film preparation and seawater nuclear pollutant elimination. The cesium adsorption film comprises a porous base film, a Prussian blue layer and a polyamide skin layer which are arranged in sequence. Wherein the porous base membrane plays a supporting role, the PB layer has excellent cesium adsorbability, and the polyamide skin layer provides selective separation. According to the cesium adsorption film, on one hand, the problems that PB particles are prone to agglomeration, difficult to recycle and the like can be solved, and the dispersity, stability and reusability of an adsorbent are improved; on the other hand, the polyamide skin layer can improve the background ion interference resistance, so that the adsorption effect of the adsorption film is improved. In addition, an ultrasonic spraying technology is adopted to assist the preparation process of the membrane, a solution is atomized into micron or nano-scale liquid drops by utilizing ultrasonic waves, a micro / nano phase interface is constructed between two phases, the contact area and the diffusion rate are regulated and controlled, and the crystallization rate, the coordination environment and the thickness of the membrane of PB can be effectively controlled.

Description

Technical Field

[0001] The invention relates to the technical field of adsorption film preparation and seawater nuclear pollutant elimination, and in particular to a cesium adsorption film and a preparation method and application thereof. Background Art

[0002] Radioactive nuclide contamination caused by nuclear waste leaks and other accidents, especially the radioactive nuclide cesium-137 ( 137 Cs), due to its long half-life (>30 years) and high solubility, can easily enter the human body through the food chain and food web, causing diseases such as cancer, leukemia and kidney damage, seriously threatening environmental safety and people's health.

[0003] Biological treatment, adsorption and membrane separation technologies are widely used to remove Cs from water. Compared with the first two methods, membrane separation technology has the advantages of high retention, low secondary pollution, simple operation and strong adaptability. However, traditional nanofiltration membranes (such as NF90 and NF270) are not very effective for Cs removal. + The removal rate is less than 83%. Prussian blue (PB), as a typical representative of ferrocyanide adsorbents, has a lattice size similar to that of cesium ions (Cs + )'s hydration radius matches that of the + Selective adsorption properties. The biocompatibility and environmental friendliness of PB make it a green and safe agent in drinking water treatment. However, PB faces two major challenges when used as an adsorbent alone: ​​first, its ultrafine powder form increases the pressure drop of the fixed bed reactor and may cause the loss of PB; second, although PB is + It has high selectivity, but in natural waters Cs + The concentration of PB is much lower than that of background ions, which limits its adsorption efficiency and economy. Preparing PB into membrane materials can reduce its loss to a certain extent. However, the current PB membrane materials and their preparation technologies have not yet been applied on a large scale. There are problems such as long preparation cycle, poor compatibility with base membrane, easy detachment of membrane layer, etc., and the adsorption efficiency in high concentration background ion environment has not yet been clarified.

[0004] Therefore, there is an urgent need to develop new materials and preparation technologies to improve the adsorption performance and durability of PB membranes and promote the efficient adsorption of cesium ions. Summary of the invention

[0005] The purpose of the present invention is to provide a cesium adsorption film and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: a cesium adsorption film, which comprises a porous substrate film, a Prussian blue (PB) layer and a polyamide skin layer arranged in sequence.

[0008] Among them, the porous substrate film serves as a carrier, which can solve the problem of difficult recovery of PB particles and improve the utilization rate of PB. The polyamide layer, as the skin layer, can not only protect the PB layer, but also play a role in intercepting background ions to reduce their interference with cesium adsorption. That is, by combining the supporting role of the porous substrate film, the adsorption performance of the PB layer (the PB layer provides adsorption sites to achieve cesium adsorption), and the selective separation performance and protection performance of the polyamide skin layer, on the one hand, problems such as easy agglomeration and difficult recovery of PB particles can be alleviated, and on the other hand, the interference of other background ions on the cesium adsorption of the PB layer can be reduced to improve the overall cesium removal performance.

[0009] Two of the technical solutions of the present invention: a preparation method of the above cesium adsorption film, comprising the following steps:

[0010] Immerse the porous substrate film in an aqueous iron salt solution, and then spray an aqueous potassium ferrocyanide solution on the surface of the porous substrate film to form a Prussian blue layer, obtaining a porous substrate film / Prussian blue composite film; immerse the porous substrate film / Prussian blue composite film in a composite aqueous solution of polyamine and iron salt, and then spray a polyacyl chloride organic solution on the surface of the Prussian blue layer to form a polyamide skin layer, obtaining a porous substrate film / Prussian blue / polyamide composite film, which is the cesium adsorption film.

[0011] Further, the concentration of the iron salt in the aqueous iron salt solution is 0.05 - 0.3 mol / L.

[0012] Further, the aqueous iron salt solution also includes tannic acid with a concentration of 0.005 - 0.5 g / 100 mL.

[0013] Tannic acid (TA) is a natural polyphenol compound containing pyrogallol groups. It has a strong interaction with the generated PB particles through coordination, thereby enhancing the compatibility between PB particles and making the PB assembly structure more dense. In addition, due to its universal surface binding ability, TA can firmly adhere to a variety of substrate materials, significantly improving the adhesion strength between the PB assembly and the support material.

[0014] Further, the time for immersing the porous substrate film in the aqueous iron salt solution is 30 - 120 min.

[0015] Further, the concentration of the aqueous potassium ferrocyanide solution is 0.1 - 0.5 mol / L.

[0016] Further, the polyamine includes one or more of piperazine, triethylenetetramine and pentaethylenehexamine.

[0017] Furthermore, in the composite aqueous solution of the polyamine and the iron salt, the concentration of the polyamine is 0.05 - 0.2 wt%, and the concentration of the iron salt is 0.05 - 0.3 mol / L.

[0018] Furthermore, the composite aqueous solution of the polyamine and the iron salt further includes tannic acid with a concentration of 0.005 - 0.5 g / 100 mL.

[0019] Furthermore, the soaking treatment time of the porous substrate membrane / Prussian blue layer composite membrane in the composite aqueous solution of the polyamine and the iron salt is 15 - 60 min.

[0020] Furthermore, the polyacyl chloride in the polyacyl chloride organic solution includes one or more of trimesoyl chloride, 2,6-pyridinedicarbonyl chloride, and 2,6-dichloropyridine-3-carbonyl chloride.

[0021] Furthermore, the concentration of the polyacyl chloride organic solution is 0.02 - 0.1 wt%.

[0022] Furthermore, the spraying of the potassium ferrocyanide aqueous solution on the surface of the porous substrate membrane is carried out by an ultrasonic spraying device, and the parameters include: the spraying power is 60 - 100% (1% is equal to 26 W), the height of the nozzle from the surface of the porous substrate membrane is 2 - 7 cm, and the spraying speed is 1 - 48 mL / min (that is, 1 - 48 mL of the potassium ferrocyanide aqueous solution is sprayed per minute).

[0023] Furthermore, the spraying of the polyacyl chloride organic solution on the surface of the Prussian blue layer is carried out by an ultrasonic spraying device, and the parameters include: the spraying power is 60 - 100%, the height of the nozzle from the surface of the Prussian blue layer is 2 - 7 cm, and the spraying speed is 0.25 - 12 mL / min.

[0024] The present invention uses ultrasonic spraying technology (i.e., the method of spraying through an ultrasonic spraying device) to assist in the preparation of the PB layer and the polyamide skin layer. The ultrasonic waves atomize the solution into micron- or nano-sized droplets, constructing a micro / nano-phase interface between the two phases, which can regulate the contact area and diffusion rate to effectively control the crystallization rate, coordination environment, and membrane thickness of PB. Among them, by adjusting the spraying parameters (such as the volume and time of the spraying solution), the nucleation and growth rate of PB can be dynamically controlled, avoiding defects (such as lattice dislocation or heterogeneous structure) caused by rapid crystallization in the traditional method; during the spraying process, the mixing of reactive ions and the solution is more uniform, enabling the coordination reaction to proceed efficiently at the interface, avoiding problems such as local reactant deficiency or aggregation that may occur in the solution method; by adjusting the spraying power, solution volume, and spraying time, the membrane thickness can be accurately controlled. At the same time, the layer-by-layer deposition characteristics of spraying avoid the thickness non-uniformity caused by diffusion limitation in the traditional dipping method.

[0025] Further, the spraying amount of the potassium ferrocyanide aqueous solution is 0.080 - 0.360 mL / cm 2 (i.e., the spraying amount on the porous substrate film per unit area (1 cm 2 ) is 0.080 - 0.360 mL).

[0026] Further, the spraying amount of the polyacyl chloride organic solution is 0.020 - 0.090 mL / cm 2 .

[0027] Further, the immersion treatment is all carried out at room temperature.

[0028] Further, after spraying the polyacyl chloride organic solution on the surface of the Prussian blue layer, it also includes the steps of washing and heat treatment.

[0029] Further, the temperature of the heat treatment is 80 °C and the time is 60 - 120 s.

[0030] The third technical solution of the present invention: Application of the above cesium adsorption film in adsorbing cesium ions in water.

[0031] Further, the application includes the following steps:

[0032] Under a pressurized condition, pass the aqueous solution containing cesium ions through the cesium adsorption film to achieve the adsorption of cesium ions.

[0033] Further, the range of the pressure is 0.1 - 1 MPa.

[0034] Optionally, the aqueous solution containing cesium ions is seawater contaminated by cesium ions.

[0035] Further, the concentration of cesium ions in the aqueous solution containing cesium ions is 0.5 - 3 ppm.

[0036] Further, the pH value of the aqueous solution containing cesium ions is 2 - 11.

[0037] Optionally, the aqueous solution containing cesium ions further contains sodium ions, potassium ions, magnesium ions and calcium ions with concentrations all of 0.5 - 3 ppm.

[0038] Further, the adsorption is carried out at room temperature.

[0039] The present invention discloses the following technical effects:

[0040] The present invention provides a cesium adsorption membrane, which includes a porous base membrane, a Prussian blue (PB) layer, and a polyamide cortical layer arranged in sequence. The porous base membrane can play the roles of support and carrier, and can solve the problem that it is difficult to recover PB particles. The polyamide cortical layer can intercept divalent ions in seawater, reduce the influence of other ions on cesium adsorption, and further protect the PB layer, improving the durability of the PB layer. In summary, on the one hand, the cesium adsorption membrane prepared by the present invention can alleviate problems such as easy agglomeration and difficult recovery of PB particles to improve the dispersibility, stability, and reusability of the adsorbent; on the other hand, the polyamide cortical layer can improve its ability to resist interference from background ions to enhance the adsorption effect of the adsorption membrane.

[0041] The present invention uses ultrasonic spray technology (i.e., a method of spraying through an ultrasonic spray device) to assist in the preparation of the PB layer and the polyamide cortical layer. Using ultrasonic spray-assisted interfacial reaction can alleviate problems such as easy agglomeration of PB particles, long construction period, and poor compatibility with the base membrane. And using ultrasonic spray technology can also reduce the thickness of the prepared polyamide cortical layer. While fixing the PB layer to prevent its shedding, it can also not affect its adsorption ability and can enhance the filtration performance of the membrane. The technical solution of the present invention is a new solution that combines membrane separation and adsorption processes.

[0042] The cesium adsorption membrane of the present invention can achieve efficient adsorption of cesium ions in water. The cesium removal rate for a cesium ion solution with a concentration of 0.5 - 3 ppm (i.e., a single salt solution) is ≥ 97%, and the cesium removal rate for a mixed solution of cesium ions and other metal ions with a concentration of 0.5 - 3 ppm (i.e., a mixed salt solution, mainly containing metal cations such as cesium ions, sodium ions, potassium ions, magnesium ions, calcium ions, etc. and anions such as chloride ions) is ≥ 96%.

[0043] The cesium adsorption membrane prepared by the present invention has excellent cesium removal performance, indicating its application feasibility in the field of seawater cesium removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is a device diagram of the ultrasonic spray device used in the specific embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and implementation schemes of the present invention.

[0047] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are merely exemplary.

[0050] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0051] It should be noted that the aspects not described in detail in the present invention are all conventional operating means in the art and are not the focus of the present invention.

[0052] As a first aspect of the present invention, the present invention provides a cesium adsorption film, which includes a porous base film, a Prussian blue (PB) layer, and a polyamide skin layer arranged in sequence.

[0053] As a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned cesium adsorption film, including the following steps:

[0054] The porous substrate membrane is immersed in an aqueous iron salt solution, and then an aqueous potassium ferrocyanide solution is sprayed on the surface of the porous substrate membrane to form a Prussian blue layer, obtaining a porous substrate membrane / Prussian blue composite membrane; the porous substrate membrane / Prussian blue composite membrane is immersed in a composite aqueous solution of polyamine and iron salt, and then a polyacyl chloride organic solution is sprayed on the surface of the Prussian blue layer to form a polyamide skin layer, obtaining a porous substrate membrane / Prussian blue / polyamide composite membrane, which is the cesium adsorption membrane.

[0055] As a preferred embodiment of the present invention, the preparation method of the adsorption membrane further specifically includes the following steps:

[0056] Immerse the porous substrate membrane (with an effective area of 11.34 cm 2 ) in an aqueous iron salt solution (prepared from iron salt, tannic acid and water, wherein the concentration of iron salt is 0.05 - 0.3 mol / L, preferably 0.1 mol / L; the concentration of tannic acid is 0.005 - 0.5 g / 100 mL, preferably 0.01 g / 100 mL) and soak it at room temperature for 30 - 120 min (preferably 60 min), take out the porous substrate membrane and use a roller to remove the residual solution on the surface of the porous substrate membrane; use an ultrasonic spraying device to uniformly spray the aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.1 - 0.5 mol / L, preferably 0.3 mol / L) onto the surface of the porous substrate membrane under the conditions that the spraying power is 60 - 100% (preferably 90%), the height of the nozzle from the surface of the porous substrate membrane is 2 - 7 cm (preferably 4 cm), and the spraying speed is 1 - 48 mL / min (preferably 5 mL / min). The spraying amount of the aqueous potassium ferrocyanide solution is 0.080 - 0.360 mL / cm 2 (preferably 0.220 mL / cm 2) so as to generate a PB layer on the surface of the porous base membrane, obtaining a porous base membrane / PB composite membrane; soaking the porous base membrane / PB composite membrane in a composite aqueous solution of polyamine and iron salt (prepared from polyamine, iron salt, tannic acid and water, wherein the concentration of polyamine is 0.05 - 0.2 wt% (preferably 0.1 wt%), the concentration of iron salt is 0.05 - 0.3 mol / L (preferably 0.1 mol / L), and the concentration of tannic acid is 0.0005 - 0.5 g / 100 mL (preferably 0.01 g / 100 mL)) for 15 - 60 min (preferably 30 min), taking out the porous base membrane / PB composite membrane and using a roller to remove the residual solution on the surface of the PB layer; subsequently, spraying a polyacyl chloride organic solution (prepared from polyacyl chloride and an organic solvent, with a concentration of 0.02 - 1 wt%, preferably 0.1 wt%) onto the surface of the PB layer under the conditions that the spraying power of the spraying device is 60 - 100% (preferably 90%), the height of the nozzle from the surface of the PB layer is 2 - 7 cm (preferably 4 cm), and the spraying speed is 0.25 - 12 mL / min (preferably 0.5 - 3 mL / min), and the spraying amount of the polyacyl chloride organic solution is 0.020 - 0.090 mL / cm 2 (preferably 0.022 mL / cm 2 ), so as to generate a polyamide skin layer on the surface of the PB layer; then rinsing the membrane surface with an organic solvent (the same organic solvent as that in the polyacyl chloride organic solution) and performing heat treatment at 80 °C for 60 - 120 s to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane).

[0057] As a preferred embodiment of the present invention, the polyamine includes one or more of piperazine, triethylenetetramine and pentaethylenehexamine.

[0058] As a preferred embodiment of the present invention, the polyacyl chloride in the polyacyl chloride organic solution includes one or more of trimellitic acid chloride, 2,6-pyridinedicarbonyl chloride and 2,6-dichloropyridine-3-carbonyl chloride.

[0059] As a preferred embodiment of the present invention, the porous base membrane includes a porous polyacrylonitrile membrane, a porous polysulfone membrane or a porous polyethersulfone membrane.

[0060] As a preferred embodiment of the present invention, the ultrasonic spraying device can be a self-made device as shown in Figure 1 , or any other ultrasonic spraying device in the art that can achieve the spraying conditions of the present invention.

[0061] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0062] In the specific embodiments of the present invention, the room temperature specifically refers to 20 - 30 °C.

[0063] All raw materials used in the specific implementation manner of the present invention are ordinary commercially available products.

[0064] The porous base membrane used in the following examples and comparative examples is a porous polyacrylonitrile membrane with a filtration accuracy of 50,000 Da and an effective area of 11.34 cm 2 .

[0065] The device diagram of the ultrasonic spray device used in the following examples and comparative examples is as shown in Figure 1 .

[0066] Example 1

[0067] A cesium adsorption membrane is prepared as follows:

[0068] The porous base membrane is statically immersed in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, wherein the concentration of ferric chloride is 0.1 mol / L and the concentration of tannic acid is 0.01 g / 100 mL) at room temperature for 60 min, and then the porous base membrane is taken out and the residual solution on the surface of the porous base membrane is removed by a roller; using an ultrasonic spray device, an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) is uniformly sprayed onto the surface of the porous base membrane at a spray power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min. The spraying amount of the aqueous solution of potassium ferrocyanide on the porous base membrane is 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous base membrane to obtain a porous base membrane / PB composite membrane; the porous base membrane / PB composite membrane is statically immersed in a composite aqueous solution of piperazine and ferric chloride (wherein the concentration of piperazine is 0.1 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min, and then the porous base membrane / PB composite membrane is taken out and the residual solution on the surface of the PB layer is removed by a roller; subsequently, using a spray device, a solution of trimesoyl chloride - n - hexane (with a concentration of 0.1 wt%) is uniformly sprayed onto the surface of the PB layer at a spray power of 90%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 0.5 mL / min. The spraying amount is 0.022 mL / cm 2 , thereby generating a polyamide skin layer on the surface of the PB layer; then the surface of the membrane is rinsed with n - hexane and heat - treated at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous base membrane / prussian blue / polyamide composite membrane). After heat - treatment, the membrane is placed in deionized water for storage.

[0069] Example 2

[0070] A cesium adsorption membrane is prepared as follows:

[0071] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min. Then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller. An aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was evenly and uniformly sprayed onto the surface of the porous base membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min. The spraying amount was 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous base membrane to obtain a porous base membrane / PB composite membrane. The porous base membrane / PB composite membrane was soaked in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine was 0.1 wt%, the concentration of ferric chloride was 0.1 mol / L, and the concentration of tannic acid was 0.01 g / 100 mL) for 30 min. Then the porous base membrane / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed with a roller. Subsequently, a solution of trimesoyl chloride in n-hexane (with a concentration of 0.1 wt%) was evenly and uniformly sprayed onto the surface of the PB layer at a spraying power of 100%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 3 mL / min. The spraying amount was 0.022 mL / cm 2 , thereby generating a polyamide skin layer on the surface of the PB layer. Then the surface of the membrane was rinsed with n-hexane and heat-treated at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane). After heat treatment, the membrane was placed in deionized water for storage.

[0072] Example 3

[0073] A cesium adsorption membrane is prepared as follows:

[0074] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min. Then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller. An aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was evenly and uniformly sprayed onto the surface of the porous base membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min. The spraying amount was 0.220 mL / cm 2, thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; soaking the porous substrate membrane / PB composite membrane in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine is 0.1 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min, taking out the porous substrate membrane / PB composite membrane and using a roller to remove the residual solution on the surface of the PB layer; subsequently, using a spraying device, under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the PB layer is 4 cm, and the spraying speed is 1.5 mL / min, spraying the trimesoyl chloride-n-hexane solution (concentration is 0.1 wt%) evenly and uniformly onto the surface of the PB layer at a constant speed, and the spraying amount is 0.066 mL / cm 2 , thereby generating a polyamide skin layer on the surface of the PB layer; then rinsing the membrane surface with n-hexane and performing heat treatment at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous substrate membrane / Prussian blue / polyamide composite membrane), and storing the membrane in deionized water after heat treatment.

[0075] Example 4

[0076] A cesium adsorption membrane is prepared as follows:

[0077] Soak the porous substrate membrane in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride is 0.1 mol / L and the concentration of tannic acid is 0.01 g / 100 mL) at room temperature for 60 min, take out the porous substrate membrane and use a roller to remove the residual solution on the surface of the porous substrate membrane; use an ultrasonic spraying device to spray the aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) evenly and uniformly onto the surface of the porous substrate membrane at a constant speed under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the porous substrate membrane is 4 cm, and the spraying speed is 5 mL / min, and the spraying amount is 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; soak the porous substrate membrane / PB composite membrane in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine is 0.1 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min, take out the porous substrate membrane / PB composite membrane and use a roller to remove the residual solution on the surface of the PB layer; subsequently, use a spraying device to spray the trimesoyl chloride-n-hexane solution (concentration is 0.1 wt%) evenly and uniformly onto the surface of the PB layer at a constant speed under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the PB layer is 6 cm, and the spraying speed is 3 mL / min, and the spraying amount is 0.022 mL / cm 2, thereby generating a polyamide skin layer on the surface of the PB layer; then, rinse the membrane surface with n-hexane and heat-treat it at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous substrate membrane / Prussian blue / polyamide composite membrane). After heat treatment, store the membrane in deionized water.

[0078] Example 5

[0079] A cesium adsorption membrane is prepared as follows:

[0080] Soak the porous substrate membrane in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid, and water, where the concentration of ferric chloride is 0.1 mol / L and the concentration of tannic acid is 0.01 g / 100 mL) at room temperature for 60 min. Take out the porous substrate membrane and use a roller to remove the remaining solution on the surface of the porous substrate membrane. Using an ultrasonic spraying device, spray the aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) evenly and uniformly onto the surface of the porous substrate membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous substrate membrane of 4 cm, and a spraying speed of 5 mL / min. The spraying amount is 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; soak the porous substrate membrane / PB composite membrane in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine is 0.05 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min. Take out the porous substrate membrane / PB composite membrane and use a roller to remove the remaining solution on the surface of the PB layer. Subsequently, use a spraying device to spray the trimesoyl chloride-n-hexane solution (with a concentration of 0.1 wt%) evenly and uniformly onto the surface of the PB layer at a spraying power of 90%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 3 mL / min. The spraying amount is 0.022 mL / cm 2 , thereby generating a polyamide skin layer on the surface of the PB layer; then, rinse the membrane surface with n-hexane and heat-treat it at 80 °C for 120 s to obtain a cesium adsorption membrane (i.e., a porous substrate membrane / Prussian blue / polyamide composite membrane). After heat treatment, store the membrane in deionized water.

[0081] Comparative Example 1

[0082] A cesium adsorption membrane is prepared as follows:

[0083] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min, then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller; an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was evenly and uniformly sprayed onto the surface of the porous base membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min, and the spraying amount was 0.220 mL / cm 2 , thereby forming a PB layer on the surface of the porous base membrane to obtain a porous base membrane / PB composite membrane.

[0084] Comparative Example 2

[0085] A cesium adsorption membrane was prepared as follows:

[0086] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min, then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller; then the porous base membrane was immersed in an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) at room temperature for 10 s to react to form a PB layer on the surface of the porous base membrane to obtain a porous base membrane / PB composite membrane; the porous base membrane / PB composite membrane was soaked in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine was 0.1 wt%, the concentration of ferric chloride was 0.1 mol / L, and the concentration of tannic acid was 0.01 g / 100 mL) for 30 min, then the porous base membrane / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed with a roller; subsequently, a solution of trimesoyl chloride - n - hexane (with a concentration of 0.1 wt%) was evenly and uniformly sprayed onto the surface of the PB layer at a spraying power of 90%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 0.5 mL / min, and the spraying amount was 0.022 mL / cm 2 , thereby forming a polyamide skin layer on the surface of the PB layer; then the surface of the membrane was rinsed with n - hexane and heat - treated at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous base membrane / prussian blue / polyamide composite membrane), and after heat - treatment, the membrane was placed in deionized water for storage.

[0087] Comparative Example 3

[0088] A cesium adsorption membrane was prepared as follows:

[0089] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric chloride was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min, and then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller; an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was evenly and uniformly sprayed onto the surface of the porous base membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min using an ultrasonic spraying device, and the spraying amount was 0.220 mL / cm 2 , thereby forming a PB layer on the surface of the porous base membrane to obtain a porous base membrane / PB composite membrane; the porous base membrane / PB composite membrane was soaked in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine was 0.1 wt%, the concentration of ferric chloride was 0.1 mol / L, and the concentration of tannic acid was 0.01 g / 100 mL) for 30 min, and then the porous base membrane / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed with a roller; subsequently, the porous base membrane / PB composite membrane was impregnated in a trimesoyl chloride - n - hexane solution (with a concentration of 0.1 wt%) at room temperature for 30 s, thereby forming a polyamide skin layer on the surface of the PB layer; then the surface of the membrane was rinsed with n - hexane and heat - treated at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous base membrane / prussian blue / polyamide composite membrane), and after heat - treatment, the membrane was placed in deionized water for storage.

[0090] Comparative Example 4

[0091] A cesium adsorption membrane is prepared as follows:

[0092] The porous base membrane was soaked in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid and water, where the concentration of ferric salt was 0.1 mol / L and the concentration of tannic acid was 0.01 g / 100 mL) at room temperature for 60 min, and then the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed with a roller; an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was evenly and uniformly sprayed onto the surface of the porous base membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min using an ultrasonic spraying device, and the spraying amount was 0.220 mL / cm 2, thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; soaking the porous substrate membrane / PB composite membrane in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine is 0.3 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min, taking out the porous substrate membrane / PB composite membrane and using a roller to remove the solution remaining on the surface of the PB layer; subsequently, using a spraying device to evenly spray a solution of trimesoyl chloride - n - hexane (concentration: 0.1 wt%) onto the surface of the PB layer at a spraying power of 50%, a height of the nozzle from the surface of the PB layer of 8 cm, and a spraying speed of 0.2 mL / min, with a spraying amount of 0.0088 mL / cm 2 , thereby generating a polyamide skin layer on the surface of the PB layer; then rinsing the membrane surface with n - hexane and performing heat treatment at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous substrate membrane / prussian blue / polyamide composite membrane), and storing the membrane in deionized water after heat treatment.

[0093] Comparative Example 5

[0094] Soak the porous substrate membrane in an aqueous solution of ferric chloride (prepared from ferric chloride, tannic acid, and water, where the concentration of ferric chloride is 0.1 mol / L and the concentration of tannic acid is 0.01 g / 100 mL) at room temperature for 60 min, take out the porous substrate membrane and use a roller to remove the solution remaining on the surface of the porous substrate membrane; use an ultrasonic spraying device to evenly spray an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, concentration: 0.3 mol / L) onto the surface of the porous substrate membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous substrate membrane of 4 cm, and a spraying speed of 5 mL / min, with a spraying amount of 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; soak the porous substrate membrane / PB composite membrane in an aqueous solution of piperazine (prepared from piperazine and water, where the concentration of piperazine is 0.1 wt%, that is, the use of ferric chloride and tannic acid is omitted) for 30 min. During the soaking process, the blue color on the surface of the porous substrate membrane / PB composite membrane gradually fades. After the soaking is completed, take out the porous substrate membrane / PB composite membrane and use a roller to remove the solution remaining on the surface of the PB layer; subsequently, use a spraying device to evenly spray a solution of trimesoyl chloride - n - hexane (concentration: 0.1 wt%) onto the surface of the PB layer at a spraying power of 90%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 0.5 mL / min, with a spraying amount of 0.022 mL / cm 2, thereby generating a polyamide skin layer on the surface of the PB layer; then, rinse the membrane surface with n-hexane and heat-treat it at 80 °C for 60 s to obtain a cesium adsorption membrane (i.e., a porous substrate membrane / Prussian blue / polyamide composite membrane). After heat treatment, store the membrane in deionized water.

[0095] In this comparative example, it was found that during the static immersion of the porous substrate membrane / PB composite membrane in the aqueous piperazine solution, the blue color on the surface of the porous substrate membrane / PB composite membrane gradually faded. This may be because when PB contacts the aqueous piperazine solution, the nitrogen atom in the piperazine molecule may coordinate with the iron ions in PB, thereby changing the original coordination structure of PB. This change in structure may lead to the dissolution of PB. In the example of the present invention, ferric chloride was added to the piperazine solution. Ferric chloride is a trivalent iron salt, and it can undergo a complexation reaction with the piperazine molecules in the piperazine solution. This complexation reaction may consume the piperazine molecules in the piperazine solution that can act on PB, thereby reducing the damage of piperazine to the structure of PB. That is to say, the presence of ferric chloride weakens the interaction between the piperazine molecules in the piperazine solution and the PB layer, thereby protecting the structure and color of the PB layer. Therefore, this phenomenon in this comparative example does not exist in the examples.

[0096] Comparative Example 6

[0097] Immerse the porous substrate membrane in an aqueous ferric chloride solution (prepared from ferric chloride and water, where the concentration of ferric chloride is 0.1 mol / L, i.e., the use of tannic acid is omitted) at room temperature for 60 min. Take out the porous substrate membrane and use a roller to remove the remaining solution on the surface of the porous substrate membrane; use an ultrasonic spraying device to evenly spray the aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) onto the surface of the porous substrate membrane at a spraying power of 90%, a height of the nozzle from the surface of the porous substrate membrane of 4 cm, and a spraying speed of 5 mL / min, and the spraying amount is 0.220 mL / cm 2 , thereby generating a PB layer on the surface of the porous substrate membrane to obtain a porous substrate membrane / PB composite membrane; immerse the porous substrate membrane / PB composite membrane in a composite aqueous solution of piperazine and ferric chloride (where the concentration of piperazine is 0.1 wt%, the concentration of ferric chloride is 0.1 mol / L, and the concentration of tannic acid is 0.01 g / 100 mL) for 30 min. Take out the porous substrate membrane / PB composite membrane and use a roller to remove the remaining solution on the surface of the PB layer; then use a spraying device to evenly spray the trimesoyl chloride - n-hexane solution (with a concentration of 0.1 wt%) onto the surface of the PB layer at a spraying power of 90%, a height of the nozzle from the surface of the PB layer of 4 cm, and a spraying speed of 0.5 mL / min, and the spraying amount is 0.022 mL / cm 2, thereby generating a polyamide skin layer on the surface of the PB layer; then, rinse the membrane surface with n - hexane and heat - treat it at 80 °C for 60 s to obtain a cesium - adsorption membrane (i.e., a porous substrate membrane / Prussian blue / polyamide composite membrane). After heat - treatment, store the membrane in deionized water.

[0098] Test Example

[0099] Test the adsorption performance of the cesium - adsorption membranes prepared in each example and comparative example.

[0100] (1) Water flux test of the cesium - adsorption membrane

[0101] First, pre - press the cesium - adsorption membrane at a pressure of 0.8 MPa for 30 min, and then conduct the test at a pressure of 0.6 MPa. The test conditions include: the operating temperature is 25 °C, and samples are taken after 10 min of testing. The test results of each example and comparative example are shown in Table 1.

[0102] Table 1

[0103] Specimen Water Flux (LMH / bar) Example 1 63.83 Example 2 43.27 Example 3 60.17 Example 4 45.24 Example 5 61.37 Comparative Example 1 74.00 Comparative Example 2 60.13 Comparative Example 3 53.20 Comparative Example 4 69.50 Comparative Example 5 80.10 Comparative Example 6 60.15

[0104] (2) Adsorption performance test of the cesium - adsorption membrane for an aqueous cesium chloride solution (i.e., a single - salt solution)

[0105] First, pre - press the cesium - adsorption membrane at a pressure of 0.8 MPa for 30 min, and then conduct the test at a pressure of 0.6 MPa. The test conditions include: the operating temperature is 25 °C, the pH value of the aqueous cesium chloride solution is 7, the feed concentration is 2 ppm, and samples are taken after 15 min of testing. The test results of each example and comparative example are shown in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] (3) Adsorption performance test of the cesium - adsorption membrane for a composite aqueous solution of cesium chloride and other metal salts (i.e., a mixed - salt solution)

[0110] First, pre - press the cesium - adsorption membrane at a pressure of 0.8 MPa for 30 min, and then conduct the test at a pressure of 0.6 MPa. The test conditions include: the operating temperature is 25 °C, the pH value of the composite aqueous solution of cesium chloride and other metal salts (sodium chloride, potassium chloride, magnesium chloride, and calcium chloride) is 7, the feed concentration is 2 ppm (the concentrations of cesium chloride, sodium chloride, potassium chloride, magnesium chloride, and calcium chloride are all 2 ppm), and samples are taken after 15 min of testing. The test results of each example and comparative example are shown in Table 3.

[0111] Table 3

[0112] Specimen Cesium Chloride Removal Rate Example 1 97.90％ Example 2 97.00％ Example 3 96.63％ Example 4 97.10％ Example 5 96.10％ Comparative Example 1 38.20％ Comparative Example 2 87.2％ Comparative Example 3 88.9％ Comparative Example 4 59.40％ Comparative Example 5 25.60％ Comparative Example 6 58.50％

[0113] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A cesium adsorption film, characterized in that, The cesium adsorption film comprises a porous substrate film, a Prussian blue layer and a polyamide skin layer which are arranged in sequence.

2. The preparation method of the cesium adsorption film according to claim 1, characterized in that, It includes the following steps: Soak the porous substrate film in an aqueous iron salt solution, and then spray an aqueous potassium ferrocyanide solution on the surface of the porous substrate film to form a Prussian blue layer, obtaining a porous substrate film / Prussian blue composite film; soak the porous substrate film / Prussian blue composite film in a composite aqueous solution of polyamine and iron salt, and then spray a polyacyl chloride organic solution on the surface of the Prussian blue layer to form a polyamide skin layer, obtaining a porous substrate film / Prussian blue / polyamide composite film, which is the cesium adsorption film.

3. The preparation method according to claim 2, characterized in that, The concentration of the iron salt in the aqueous iron salt solution is 0.05 - 0.3 mol / L; And / or, the aqueous iron salt solution further includes tannic acid with a concentration of 0.005 - 0.5 g / 100 mL; And / or, the soaking time of the porous substrate film in the aqueous iron salt solution is 30 - 120 min.

4. The preparation method according to claim 2, characterized in that, The concentration of the aqueous potassium ferrocyanide solution is 0.1 - 0.5 mol / L.

5. The preparation method according to claim 2, characterized in that, The polyamine includes one or more of piperazine, triethylenetetramine and pentaethylenehexamine; And / or, the concentration of the polyamine in the composite aqueous solution of polyamine and iron salt is 0.05 - 0.2 wt%, and the concentration of the iron salt is 0.05 - 0.3 mol / L; And / or, the composite aqueous solution of polyamine and iron salt further includes tannic acid with a concentration of 0.005 - 0.5 g / 100 mL; And / or, the soaking time of the porous substrate film / Prussian blue layer composite film in the composite aqueous solution of polyamine and iron salt is 15 - 60 min.

6. The preparation method according to claim 2, characterized in that, The polyacyl chloride in the polyacyl chloride organic solution includes one or more of trimesoyl chloride, 2,6-pyridinedicarbonyl chloride and 2,6-dichloropyridine-3-carbonyl chloride; And / or, the concentration of the polyacyl chloride organic solution is 0.02 - 0.1 wt%.

7. The preparation method according to claim 2, wherein The spraying of the aqueous potassium ferrocyanide solution on the surface of the porous substrate film is carried out by an ultrasonic spraying device, and the parameters include: the spraying power is 60 - 100%, the height of the nozzle from the surface of the porous substrate film is 2 - 7 cm, and the spraying speed is 1 - 48 mL / min; And / or, the spraying of the polyacyl chloride organic solution on the surface of the Prussian blue layer is carried out by an ultrasonic spraying device, and the parameters include: the spraying power is 60 - 100%, the height of the nozzle from the surface of the Prussian blue layer is 2 - 7 cm, and the spraying speed is 0.25 - 12 mL / min.

8. The preparation method according to claim 2, characterized in that, The spraying amount of the potassium ferrocyanide aqueous solution is 0.080 - 0.360 mL / cm 2 ; and / or, the spraying amount of the polyacyl chloride organic solution is 0.020 - 0.090 mL / cm 2 .

9. The application of the cesium adsorption film according to claim 1 in adsorbing cesium ions in water.

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