Cesium adsorption membrane and preparation method and application thereof

Abstract

The application discloses a cesium adsorption membrane and a preparation method and application thereof, and belongs to the technical field of adsorption membrane preparation and seawater nuclear pollutant elimination. The cesium adsorption membrane comprises a porous base film, a Prussian blue layer and a polyamide skin layer which are sequentially arranged. The porous base film plays a supporting role, the PB layer has excellent cesium adsorption, and the polyamide skin layer provides selective separation. The cesium adsorption membrane can relieve the problems of PB particle easy agglomeration and difficult recovery, so as to improve the dispersibility, stability and reusability of the adsorbent. On the other hand, the polyamide skin layer can improve the anti-background ion interference ability, so as to improve the adsorption effect of the adsorption membrane. In addition, the application adopts an ultrasonic spraying technology to assist the membrane preparation process, uses ultrasonic waves to atomize the solution into micron or nanometer level droplets, constructs a micro / nano phase interface between two phases, adjusts the contact area and diffusion rate, and can effectively control the crystallization rate, coordination environment and thickness of the PB and the membrane.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of adsorption membrane preparation and seawater nuclear pollutant removal, and particularly relates to a cesium adsorption membrane and a preparation method and application thereof. BACKGROUND

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

[0003] Biological treatment, adsorption and membrane separation technology are widely used for Cs removal in water bodies, and compared with the first two methods, the membrane separation technology has the advantages of high interception, low secondary pollution, simple operation and strong adaptability. However, the removal rate of Cs + by the traditional nanofiltration membrane (such as NF90 and NF270) is less than 83%. Prussian blue (PB), as a typical representative of ferricyanide adsorbent, exhibits excellent selective adsorption characteristics of Cs + because its lattice size matches the hydration radius of cesium ions (Cs + ). The biocompatibility and environmental friendliness of PB make it a green and safe reagent in drinking water treatment. However, PB as an adsorbent alone faces two major challenges: first, its ultrafine powder form increases the pressure drop of the fixed bed reactor and may cause loss of PB; second, although PB has high selectivity for Cs + , the concentration of Cs + in natural water bodies is much lower than that of background ions, which limits its adsorption efficiency and economy. Preparing PB into a membrane material can to some extent reduce its loss, however, the current PB membrane material and its preparation technology has not realized large-scale application, and there are problems such as long preparation period, poor compatibility with the base membrane, easy peeling of the membrane layer, and the adsorption efficiency in the environment with high concentration of background ions has not been determined.

[0004] Therefore, it is urgent to develop new materials and preparation technologies to improve the adsorption performance and durability of PB membrane and promote efficient adsorption of cesium ions. SUMMARY

[0005] The purpose of the present application is to provide a cesium adsorption membrane and a preparation method and application thereof to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present application provides the following solutions:

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

[0008] The porous base 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 not only protects the PB layer but also plays a role in retaining background ions to reduce their interference with cesium adsorption. That is, by combining the supporting effect of the porous base 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, the problems of easy agglomeration and difficult recovery of PB particles can be alleviated, and on the other hand, the interference of other background ions with the PB layer adsorbing cesium can be reduced to improve the overall cesium removal performance.

[0009] The second technical solution of the present application: a preparation method of the above-mentioned cesium adsorption film, comprising the following steps:

[0010] The porous base film is soaked in an aqueous iron salt solution, then a potassium ferrocyanide aqueous solution is sprayed on the surface of the porous base film to form a Prussian blue layer, and a porous base film / Prussian blue composite film is obtained; the porous base film / Prussian blue composite film is soaked in a composite aqueous solution of a polyamine and an iron salt, then a polyacyl chloride organic solution is sprayed on the surface of the Prussian blue layer to form a polyamide skin layer, and a porous base film / Prussian blue / polyamide composite film is obtained, 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 further comprises tannic acid with a concentration of 0.005-0.5 g / 100 mL.

[0013] Tannic acid (TA) is a natural polyphenol compound containing o-benzene triol groups, which strongly interacts with the generated PB particles through coordination, thereby enhancing the compatibility between PB particles and making the PB assembly structure more compact. In addition, thanks 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 supporting material.

[0014] Further, the soaking time of the porous base film in the aqueous iron salt solution is 30-120 min.

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

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

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

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

[0019] Further, the time for soaking the porous base film / Prussian blue layer composite film in the complex aqueous solution of the polyamine and the iron salt is 15-60min.

[0020] Further, the polybasic acid chloride in the polybasic acid chloride organic solution comprises one or more of trimesoyl chloride, 2,6-pyridine dicarbonyl chloride and 2,6-dichloropyridine-3-carbonyl chloride.

[0021] Further, the concentration of the polybasic acid chloride in the polybasic acid chloride organic solution is 0.02-0.1wt%.

[0022] Further, the spraying of the aqueous potassium ferrocyanide solution on the surface of the porous base film is performed by an ultrasonic spraying device, and the parameters include: the spraying power is 60-100%(1% equals 26W), the height of the nozzle from the surface of the porous base film is 2-7cm, and the spraying speed is 1-48mL / min (i.e. 1-48mL of the aqueous potassium ferrocyanide solution is sprayed per minute).

[0023] Further, the spraying of the polybasic acid chloride organic solution on the surface of the Prussian blue layer is performed 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 2-7cm, and the spraying speed is 0.25-12mL / min.

[0024] The present application adopts the ultrasonic spraying technology (i.e. the method of spraying by an ultrasonic spraying device) to assist the preparation of the PB layer and the polyamide skin layer, uses ultrasonic waves to atomize the solution into micron or nanometer level droplets, constructs a micro / nano phase interface between the two phases, can control the contact area and the diffusion rate, and can effectively control the crystallization rate, the coordination environment and the film thickness of the PB. Among them, by adjusting the spraying parameters (such as the volume and time of the spraying solution), the nucleation and growth rate of the PB can be dynamically controlled, and the defects (such as lattice dislocation or heterogeneous structure) caused by rapid crystallization in the traditional method can be avoided; the mixing of the reaction ions and the solution is more uniform during the spraying process, which can make the coordination reaction efficiently carried out at the interface, and avoid the local reactant deficiency or aggregation problem that may occur in the solution method; by adjusting the spraying power, the solution volume and the spraying time, the film thickness can be accurately controlled, and the layer-by-layer deposition characteristics of the spraying avoid the thickness unevenness caused by the diffusion limitation in the traditional immersion method.

[0025] Further, the spraying amount of the aqueous potassium ferrocyanide solution is 0.080-0.360 mL / cm 2 (i.e. the spraying amount on the porous base 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 soaking treatment is carried out at room temperature.

[0028] Further, after the polyacyl chloride organic solution is sprayed on the surface of the Prussian blue layer, the steps of washing and heat treatment are further included.

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

[0030] The third technical solution of the present application is the application of the above-mentioned cesium adsorption film in adsorbing cesium ions in water.

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

[0032] The aqueous solution containing cesium ions is passed through the cesium adsorption film under pressure to achieve the adsorption of cesium ions.

[0033] Further, the pressure ranges from 0.1 to 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, each with a concentration of 0.5-3 ppm.

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

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

[0040] The present invention provides a cesium adsorption membrane, comprising a porous base membrane, a Prussian blue (PB) layer, and a polyamide cortex layer, which are sequentially arranged. The porous base membrane can serve as a support and carrier, solving the problem of difficult recovery of PB particles. The polyamide cortex layer can intercept divalent ions in seawater, reducing the impact of other ions on cesium adsorption. The polyamide cortex layer can further protect the PB layer, improving the durability of the PB layer. In summary, the cesium adsorption membrane prepared by the present invention can, on the one hand, alleviate the problems of easy agglomeration and difficult recovery of PB particles, thereby improving the dispersibility, stability, and reusability of the adsorbent; on the other hand, the polyamide cortex layer can improve its ability to resist background ion interference, thereby improving the adsorption effect of the adsorption membrane.

[0041] The present invention utilizes ultrasonic spray technology (i.e., spraying using an ultrasonic spray device) to assist in the preparation of the PB layer and polyamide skin layer. Ultrasonic spray-assisted interfacial reaction alleviates the problems of PB particle agglomeration, long construction period, and poor compatibility with the base membrane. Ultrasonic spray technology can also reduce the thickness of the prepared polyamide skin layer, securing the PB layer to prevent it from falling off without affecting its adsorption capacity, thereby enhancing the membrane's filtration performance. The technical solution of the present invention is a novel approach 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, with a cesium removal rate of ≥97% for a cesium ion solution with a concentration of 0.5-3 ppm (i.e., a single salt solution), and a cesium removal rate of ≥96% 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, and calcium ions, and anions such as chloride ions).

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

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 2 is a diagram of an ultrasonic spray device used in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0046] The detailed description set forth below of various illustrative embodiments explains the principles of the application and the best mode presently contemplated by the inventors for carrying out the application. It will be understood that the detailed description is merely meant to illustrate certain aspects of the application, and is not intended to limit the scope of the application.

[0047] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, the use of the term "about" in relation to a value or a range of values is intended to include each and every value falling within the range and each and every value falling within the range as well as the value itself. The upper and lower limits of each range are included in the range. The upper and lower limits of each range are also included in the range.

[0048] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in detail the methods and / or materials that are related to the present application. In the case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0049] Many modifications and variations of the present application described in the detailed description of the application can be made by those skilled in the art without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples are illustrative only.

[0050] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0051] It should be noted that the present application does not describe in detail the conventional operation means in the art, and is not the focus of the present application.

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

[0053] As a second aspect of the present application, the present application provides a preparation method of the above-mentioned cesium adsorption membrane, comprising the following steps:

[0054] The porous base film is immersed in an aqueous solution of iron salt, and then an aqueous solution of potassium ferrocyanide is sprayed on the surface of the porous base film to form a Prussian blue layer, thereby obtaining a porous base film / Prussian blue composite film; the porous base film / Prussian blue composite film 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, thereby obtaining a porous base film / Prussian blue / polyamide composite film, i.e. the cesium adsorption film.

[0055] As a preferred embodiment of the application, the preparation method of the adsorption film, more specifically, the steps include:

[0056] The porous base film (effective area: 11.34 cm 2 ) is immersed in an aqueous solution of iron salt (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) at room temperature for 30-120 min (preferably 60 min), and the porous base film is taken out and the residual solution on the surface of the porous base film is removed by a roller; an aqueous solution of potassium ferrocyanide (prepared from potassium ferrocyanide and water, with a concentration of 0.1-0.5 mol / L, preferably 0.3 mol / L) is uniformly sprayed on the surface of the porous base film by using an ultrasonic spraying device under the following conditions: spraying power: 60-100% (preferably 90%); height of the nozzle from the surface of the porous base film: 2-7 cm (preferably 4 cm); spraying speed: 1-48 mL / min (preferably 5 mL / min); the spraying amount of the aqueous solution of potassium ferrocyanide is 0.080-0.360 mL / cm 2 (preferably 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 is immersed in a composite aqueous solution of polyamine and iron salt (prepared by polyamine, iron salt, tannic acid and water, wherein the concentration of polyamine is 0.05-0.2wt% (preferably 0.1wt%), the concentration of iron salt is 0.05-0.3mol / L (preferably 0.1mol / L), and the concentration of tannic acid is 0.0005-0.5g / 100mL (preferably 0.01g / 100mL)) for 15-60min (preferably 30min), and the porous base membrane is taken out. The base film / PB composite film is formed and the residual solution on the surface of the PB layer is removed by a roller; then, a polyacyl chloride organic solution (prepared by polyacyl chloride and organic solvent, with a concentration of 0.02-1wt%, preferably 0.1wt%) is sprayed onto the surface of the PB layer using a spray device at a spray power of 60-100% (preferably 90%), a height of 2-7 cm (preferably 4 cm) from the nozzle to the surface of the PB layer, and a spraying speed of 0.25-12 mL / min (preferably 0.5-3 mL / min). The spraying amount of the polyacyl chloride organic solution is 0.020-0.090 mL / cm 2 (Preferably 0.022 mL / cm 2 ), thereby forming a polyamide skin layer on the surface of the PB layer; then the membrane surface is rinsed with an organic solvent (the same organic solvent as the solvent in the polyacyl chloride organic solution) and heat-treated at 80°C for 60-120s 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 trimesoyl 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 spray device can be selected as follows Figure 1 The homemade device shown can also be any other ultrasonic spray device in the art that can achieve the spraying conditions of the present invention.

[0061] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0062] The room temperature involved in the specific implementation manner of the present invention specifically refers to 20-30°C.

[0063] Each raw material used in the present application is a common commercially available product.

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

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

[0066] Example 1

[0067] A cesium adsorption film was prepared by the following steps:

[0068] The porous base film was immersed in an aqueous ferric chloride solution (prepared from ferric chloride, tannic acid and water, wherein 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. The porous base film was taken out and the residual solution on the surface of the porous base film was removed by a roller. The aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was uniformly and evenly sprayed onto the surface of the porous base film by using the ultrasonic spraying device under the conditions of a spraying power of 90%, a height of the nozzle from the surface of the porous base film of 4 cm and a spraying speed of 5 mL / min. The spraying amount of the aqueous potassium ferrocyanide solution on the porous base film was 0.220 mL / cm 2 , so as to form a PB layer on the surface of the porous base film and obtain a porous base film / PB composite film. The porous base film / PB composite film was immersed in a composite aqueous solution of piperazine and ferric chloride (wherein 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. The porous base film / PB composite film was taken out and the residual solution on the surface of the PB layer was removed by a roller. Then, the solution of trimesoyl chloride-n-hexane (with a concentration of 0.1 wt%) was uniformly and evenly sprayed onto the surface of the PB layer by using the spraying device under the conditions of 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. The spraying amount was 0.022 mL / cm 2 , so as to form a polyamide skin layer on the surface of the PB layer. The surface of the film was then flushed with n-hexane and heat treated at a temperature of 80°C for 60 s to obtain a cesium adsorption film (i.e. a porous base film / Prussian blue / polyamide composite film). After heat treatment, the film was stored in deionized water.

[0069] Example 2

[0070] A cesium adsorption film was prepared by the following steps:

[0071] ​The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. The aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) is uniformly and evenly sprayed onto the surface of the porous base membrane by using an ultrasonic spraying device under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the porous base membrane is 4 cm, and the spraying speed is 5 mL / min, and the spraying amount is 0.220 mL / cm 2 Thus, a PB layer is formed on the surface of the porous base membrane, and a porous base membrane / PB composite membrane is obtained. The porous base membrane / PB composite membrane is 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 using a roller. Subsequently, the solution of trimesoyl chloride-n-hexane (with a concentration of 0.1 wt%) is uniformly and evenly sprayed onto the surface of the PB layer by using a spraying device under the conditions that the spraying power is 100%, the height of the nozzle from the surface of the PB layer is 4 cm, and the spraying speed is 3 mL / min, and the spraying amount is 0.022 mL / cm 2 Thus, a polyamide skin layer is formed on the surface of the PB layer. Then, the membrane surface is washed with n-hexane, and the membrane is heat-treated at a temperature of 80°C for 60 s, so as to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane). After the heat treatment, the membrane is stored in deionized water.

[0072] Example 3

[0073] A cesium adsorption membrane is prepared by the following steps:

[0074] The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. The aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) is uniformly and evenly sprayed onto the surface of the porous base membrane by using an ultrasonic spraying device under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the porous base membrane is 4 cm, and the spraying speed is 5 mL / min, and the spraying amount is 0.220 mL / cm 2to generate a PB layer on the surface of the porous substrate, to obtain a porous substrate / PB composite membrane; the porous substrate / PB composite membrane is soaked 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, the porous substrate / PB composite membrane is taken out and the residual solution on the surface of the PB layer is removed by using a roller; then, a trimesoyl chloride-n-hexane solution (concentration of 0.1 wt%) is uniformly and evenly sprayed onto the surface of the PB layer by 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, and the spraying amount is 0.066 mL / cm 2 to generate a polyamide skin layer on the surface of the PB layer; then, the membrane surface is washed with n-hexane, and the membrane is heat-treated at a temperature of 80°C for 60 s to obtain a cesium adsorption membrane (i.e., a porous substrate / PB / polyamide composite membrane), and after heat treatment, the membrane is stored in deionized water.

[0075] Example 4

[0076] A cesium adsorption membrane is prepared by the following steps:

[0077] The porous substrate is soaked in an aqueous ferric chloride solution (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, the porous substrate is taken out and the residual solution on the surface of the porous substrate is removed by using a roller; a potassium ferrocyanide aqueous solution (prepared from potassium ferrocyanide and water, concentration of 0.3 mol / L) is uniformly and evenly sprayed onto the surface of the porous substrate by using an ultrasonic spraying device under the conditions that the spraying power is 90%, the height of the nozzle from the surface of the porous substrate is 4 cm, and the spraying speed is 5 mL / min, and the spraying amount is 0.220 mL / cm 2 to generate a PB layer on the surface of the porous substrate, to obtain a porous substrate / PB composite membrane; the porous substrate / PB composite membrane is soaked 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, the porous substrate / PB composite membrane is taken out and the residual solution on the surface of the PB layer is removed by using a roller; then, a trimesoyl chloride-n-hexane solution (concentration of 0.1 wt%) is uniformly and evenly sprayed onto the surface of the PB layer by 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 6 cm, and the spraying speed is 3 mL / min, and the spraying amount is 0.022 mL / cm 2, thus forming a polyamide skin layer on the surface of the PB layer; then rinsing the membrane surface with n-hexane and heat treating at a temperature of 80°C for 60s to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane), and after heat treatment, storing the membrane in deionized water.

[0078] Example 5

[0079] A cesium adsorption membrane, the preparation steps being as follows:

[0080] The porous base membrane was immersed in an aqueous ferric chloride solution (prepared from ferric chloride, tannic acid and water, wherein 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, the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed by a roller; an aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was uniformly and evenly sprayed onto the surface of the porous base membrane by using an ultrasonic spraying device under the conditions of a spraying power of 90%, a height of the spraying head 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 , thus 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 immersed in a composite aqueous solution of piperazine and ferric chloride (wherein the concentration of piperazine was 0.05 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, the porous base membrane / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed by a roller; then a solution of trimesoyl chloride-n-hexane (with a concentration of 0.1 wt%) was uniformly and evenly sprayed onto the surface of the PB layer by using a spraying device under the conditions of a spraying power of 90%, a height of the spraying head from the surface of the PB layer of 4 cm and a spraying speed of 3 mL / min, and the spraying amount was 0.022 mL / cm 2 , thus forming a polyamide skin layer on the surface of the PB layer; then rinsing the membrane surface with n-hexane and heat treating at a temperature of 80°C for 120s to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane), and after heat treatment, storing the membrane in deionized water.

[0081] Comparative Example 1

[0082] A cesium adsorption membrane, the preparation steps being as follows:

[0083] The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. The porous base membrane is uniformly and evenly sprayed with an aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, and having a concentration of 0.3 mol / L) at a spraying power of 90%, a height of 4 cm between the nozzle and the surface of the porous base membrane, and a spraying speed of 5 mL / min, so that the spraying amount is 0.220 mL / cm 2 Thus, a PB layer is formed on the surface of the porous base membrane, and a porous base membrane / PB composite membrane is obtained.

[0084] Comparative Example 2

[0085] A cesium adsorption membrane is prepared by the following steps:

[0086] The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. The porous base membrane is then immersed in an aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, and having a concentration of 0.3 mol / L) at room temperature for 10 s, so that a reaction occurs and a PB layer is formed on the surface of the porous base membrane, thereby obtaining a porous base membrane / PB composite membrane. The porous base membrane / PB composite membrane is 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 using a roller. Subsequently, a trimesoyl chloride-n-hexane solution (having a concentration of 0.1 wt%) is uniformly and evenly sprayed onto the surface of the PB layer by using a spraying device at a spraying power of 90%, a height of 4 cm between the nozzle and the surface of the PB layer, and a spraying speed of 0.5 mL / min, so that the spraying amount is 0.022 mL / cm 2 Thus, a polyamide skin layer is formed on the surface of the PB layer. The membrane surface is then washed with n-hexane, and the membrane is heat treated at a temperature of 80°C for 60 s, thereby obtaining a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane). After the heat treatment, the membrane is stored in deionized water.

[0087] Comparative Example 3

[0088] A cesium adsorption membrane is prepared by the following steps:

[0089] The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. An aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) is uniformly and evenly sprayed onto the surface of the porous base membrane by using an ultrasonic spraying device under the conditions of a spraying power of 90%, a height of the spraying head from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min, and the spraying amount is 0.220 mL / cm 2 Thus, a PB layer is formed on the surface of the porous base membrane, and a porous base membrane / PB composite membrane is obtained. The porous base membrane / PB composite membrane is 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 using a roller. Subsequently, the porous base membrane / PB composite membrane is immersed in a trimesoyl chloride-n-hexane solution (with a concentration of 0.1 wt%) at room temperature for 30 s, so as to form a polyamide skin layer on the surface of the PB layer. Then, the membrane surface is washed with n-hexane, and the membrane is subjected to heat treatment at a temperature of 80°C for 60 s, so as to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane). After the heat treatment, the membrane is stored in deionized water.

[0090] Comparative Example 4

[0091] A cesium adsorption membrane is prepared by the following steps:

[0092] The porous base membrane is immersed in an aqueous ferric chloride solution (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 using a roller. An aqueous potassium ferrocyanide solution (prepared from potassium ferrocyanide and water, with a concentration of 0.3 mol / L) is uniformly and evenly sprayed onto the surface of the porous base membrane by using an ultrasonic spraying device under the conditions of a spraying power of 90%, a height of the spraying head from the surface of the porous base membrane of 4 cm, and a spraying speed of 5 mL / min, and the spraying amount is 0.220 mL / cm 2to form a PB layer on the surface of the porous substrate, thereby obtaining a porous substrate / PB composite membrane; the porous substrate / PB composite membrane was immersed in a composite aqueous solution of piperazine and ferric chloride (wherein the concentration of piperazine was 0.3 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 substrate / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed by using a roller; subsequently, the trimesoyl chloride-n-hexane solution (concentration of 0.1 wt%) was uniformly and evenly sprayed onto the surface of the PB layer by using a spraying device under the conditions that the spraying power was 50%, the height of the nozzle from the surface of the PB layer was 8 cm, and the spraying speed was 0.2 mL / min, and the spraying amount was 0.0088 mL / cm 2 to form a polyamide skin layer on the surface of the PB layer; then the membrane surface was washed with n-hexane, and the membrane was heat-treated at a temperature of 80 °C for 60 s, thereby obtaining a cesium adsorption membrane (i.e., a porous substrate / PB / polyamide composite membrane); after heat treatment, the membrane was stored in deionized water.

[0093] Comparative Example 5

[0094] The porous substrate was immersed in an aqueous ferric chloride solution (prepared from ferric chloride, tannic acid and water, wherein 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 substrate was taken out and the residual solution on the surface of the porous substrate was removed by using a roller; the potassium ferrocyanide aqueous solution (prepared from potassium ferrocyanide and water, concentration of 0.3 mol / L) was uniformly and evenly sprayed onto the surface of the porous substrate by using an ultrasonic spraying device under the conditions that the spraying power was 90%, the height of the nozzle from the surface of the porous substrate was 4 cm, and the spraying speed was 5 mL / min, and the spraying amount was 0.220 mL / cm 2 to form a PB layer on the surface of the porous substrate, thereby obtaining a porous substrate / PB composite membrane; the porous substrate / PB composite membrane was immersed in an aqueous piperazine solution (prepared from piperazine and water, wherein the concentration of piperazine was 0.1 wt%, i.e., the use of ferric chloride and tannic acid was omitted) for 30 min, and during the immersion process, the blue color on the surface of the porous substrate / PB composite membrane gradually faded, after the immersion was completed, the porous substrate / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed by using a roller; subsequently, the trimesoyl chloride-n-hexane solution (concentration of 0.1 wt%) was uniformly and evenly sprayed onto the surface of the PB layer by using a spraying device under the conditions that the spraying power was 90%, the height of the nozzle from the surface of the PB layer was 4 cm, and the spraying speed was 0.5 mL / min, and the spraying amount was 0.022 mL / cm 2, thus forming a polyamide skin layer on the surface of the PB layer; then the surface of the membrane was rinsed with n-hexane, and the membrane was heat treated at a temperature of 80°C for 60s to obtain a cesium adsorption membrane (i.e., a porous base membrane / Prussian blue / polyamide composite membrane), and after heat treatment, the membrane was stored in deionized water.

[0095] In the present comparative example, it was found that during the process of standing and soaking the porous base membrane / PB composite membrane in the piperazine aqueous solution, the blue color on the surface of the porous base membrane / PB composite membrane gradually faded, which may be because when the PB was in contact with the piperazine aqueous solution, the nitrogen atoms in the piperazine molecules may have coordinated with the iron ions in the PB, thus changing the original coordination structure of the PB. This change in structure may lead to the dissolution of the PB. However, in the example of the present application, ferric chloride was added to the piperazine solution, which is a trivalent iron salt and can undergo complexation with the piperazine molecules in the piperazine solution. This complexation reaction may consume the piperazine molecules in the piperazine solution that can interact with the PB, thus reducing the destruction of the PB structure by piperazine. That is, 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, the phenomenon in the present comparative example does not exist in the example.

[0096] Comparative Example 6

[0097] The porous base membrane was soaked in a ferric chloride aqueous solution (prepared by ferric chloride and water, wherein the concentration of ferric chloride was 0.1 mol / L, i.e., the use of tannic acid was omitted) at room temperature for 60 min, and the porous base membrane was taken out and the residual solution on the surface of the porous base membrane was removed by a roller; using an ultrasonic spraying device, a potassium ferrocyanide aqueous solution (prepared by potassium ferrocyanide and water, with a concentration of 0.3 mol / L) was uniformly and evenly 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 , thus 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 (wherein 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 the porous base membrane / PB composite membrane was taken out and the residual solution on the surface of the PB layer was removed by a roller; then using a spraying device, a trimesoyl chloride-n-hexane solution (concentration of 0.1 wt%) was uniformly and evenly 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 membrane surface was rinsed with n-hexane and heat-treated at 80°C for 60s to obtain a cesium adsorption membrane (i.e., porous base membrane / Prussian blue / polyamide composite membrane). After heat treatment, the membrane was placed in deionized water for storage.

[0098] Test Case

[0099] The adsorption performance of the cesium adsorption membranes prepared in each embodiment and comparative example was tested.

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

[0101] The cesium adsorption membrane was first pre-pressed at a pressure of 0.8 MPa for 30 minutes and then tested at a pressure of 0.6 MPa. The test conditions included an operating temperature of 25° C. and sampling after 10 minutes of testing. The test results of the embodiments and comparative examples are shown in Table 1.

[0102] Table 1

[0103] Sample 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) Test of the adsorption performance of cesium adsorption film on cesium chloride aqueous solution (i.e., single salt solution)

[0105] The cesium adsorption membrane was first pre-pressed at a pressure of 0.8 MPa for 30 minutes and then tested at a pressure of 0.6 MPa. The test conditions included: an operating temperature of 25°C, a pH value of 7 in the cesium chloride aqueous solution, a feed concentration of 2 ppm, and sampling after 15 minutes of testing. The test results of the embodiments and comparative examples are shown in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] (3) Test of the adsorption performance of cesium adsorption film on composite aqueous solutions of cesium chloride and other metal salts (i.e., mixed salt solutions)

[0110] The cesium adsorption membrane was first pre-pressed at a pressure of 0.8 MPa for 30 minutes and then tested at a pressure of 0.6 MPa. The test conditions included an operating temperature of 25°C, a pH of 7 for a composite aqueous solution of cesium chloride and other metal salts (sodium chloride, potassium chloride, magnesium chloride, and calcium chloride), a feed concentration of 2 ppm (the concentrations of cesium chloride, sodium chloride, potassium chloride, magnesium chloride, and calcium chloride were all 2 ppm), and sampling was performed 15 minutes after the test. The test results for the Examples and Comparative Examples are shown in Table 3.

[0111] Table 3

[0112] Sample Cesium chloride removal 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 above-described embodiments are merely intended to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements of the present application made by those skilled in the art, without departing from the design spirit of the present application, should fall within the scope of the present application defined by the claims.

Claims

1. A method for producing a cesium adsorbing membrane, characterized by, The cesium adsorption film comprises a porous base film, a Prussian blue layer and a polyamide skin layer arranged in sequence; the preparation method comprises the following steps: immersing the porous base film in an aqueous iron salt solution, then spraying a potassium ferrocyanide aqueous solution on the surface of the porous base film to form a Prussian blue layer, thereby obtaining a porous base film / Prussian blue composite film; immersing the porous base film / Prussian blue composite film in a composite aqueous solution of a polyamine and an iron salt, then spraying a polybasic acid chloride organic solution on the surface of the Prussian blue layer to form a polyamide skin layer, thereby obtaining a porous base film / Prussian blue / polyamide composite film, i.e. the cesium adsorption film; the concentration of the iron salt in the aqueous iron salt solution is 0.05-0.3 mol / L; the aqueous iron salt solution further comprises tannic acid with a concentration of 0.005-0.5 g / 100 mL; the immersing time of the porous base film in the aqueous iron salt solution is 30-120 min; the spraying of the potassium ferrocyanide aqueous solution on the surface of the porous base film is performed by an ultrasonic spraying device, and the parameters include: a spraying power of 60-100%, a height of the nozzle from the surface of the porous base film of 2-7 cm, and a spraying speed of 1-48 mL / min; the spraying of the polybasic acid chloride organic solution on the surface of the Prussian blue layer is performed by an ultrasonic spraying device, and the parameters include: a spraying power of 60-100%, a height of the nozzle from the surface of the Prussian blue layer of 2-7 cm, and a spraying speed of 0.25-12 mL / min; The spraying amount of the potassium ferrocyanide aqueous solution is 0.080-0.360 mL / cm 2 ; The spraying amount of the polybasic acid chloride organic solution is 0.020-0.090 mL / cm 2 .

2. The production method according to claim 1, wherein the concentration of the potassium ferrocyanide aqueous solution is 0.1-0.5 mol / L.

3. The production method according to claim 1, wherein the polyamine comprises one or more of piperazine, triethylenetetramine and pentaethylenehexamine; and / or, the concentration of the polyamine in the composite aqueous solution of the polyamine and the 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 the polyamine and the iron salt further comprises tannic acid with a concentration of 0.005-0.5 g / 100 mL; and / or, the immersing time of the porous base film / Prussian blue layer composite film in the composite aqueous solution of the polyamine and the iron salt is 15-60 min.

4. The production method according to claim 1, wherein the polybasic acid chloride in the polybasic acid chloride organic solution comprises one or more of trimesoyl chloride, 2,6-pyridinedicarbonyl chloride and 2,6-dichloropyridine-3-carbonyl chloride; and / or, the concentration of the polybasic acid chloride organic solution is 0.02-0.1 wt%.

5. A cesium adsorption film prepared by the preparation method of any one of claims 1-4.

6. Use of the cesium adsorption film of claim 5 in adsorbing cesium ions in water.

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