Nanofiber membrane for cesium adsorption and production method therefor

Abstract

The present invention relates to a nanofiber membrane for cesium adsorption and a production method therefor. Specifically, the present invention provides a production method for a nanofiber membrane for cesium adsorption, in which an iron salt, which is a Prussian blue precursor, is mixed with cellulose acetate to form a nanofiber by electrospinning, and then the nanofiber is reacted with a Prussian blue cyanide solution so that Prussian blue is uniformly crystallized and immobilized on the surface of the nanofiber. This method has the effect of preventing the detachment of Prussian blue and maximizing the surface area of contact with cesium ions, thereby improving adsorption activity, and is suitable for radioactive contaminated water treatment and environmental purification.

Description

Nanofiber membrane for cesium adsorption and method for manufacturing the same

[0001] The present invention relates to a nanofiber membrane for cesium adsorption and a method for manufacturing the same.

[0002] Radioactive cesium (Cs-137) emits powerful beta and gamma radiation even at low concentrations, causing severe health damage. In treating radioactive contaminated soil and water, adsorbents are required to selectively remove specific radioactive materials because radioactive cesium is present in very low concentrations compared to abundant ions such as potassium (K) and sodium (Na).

[0003] Prussian Blue (PB) has long been used for the removal of radioactive cesium. PB possesses porous properties through a face-centered cubic lattice structure in which high-spin iron (III) and low-spin iron (II) are coordinated to cyanide, and it can adsorb cesium ions by acting as a molecular sieve and ion exchanger.

[0004] However, PB nanoparticles form stable colloids in water, posing a risk of causing secondary pollution. Accordingly, research has been conducted to improve cesium removal efficiency by immobilizing PB on various matrices, such as nonwoven fabrics, chitosan, and membranes. While existing studies have demonstrated the excellent adsorption capacity of PB, most focused on impregnation and inclusion methods within the matrix, resulting in poor cesium removal performance; therefore, further performance improvement is required in terms of cesium removal capabilities.

[0005] The present invention aims to provide a nanofiber membrane for cesium adsorption in the form of a nanofiber membrane containing Prussian blue and a method for manufacturing the same.

[0006] As an example, the method for manufacturing a cesium adsorption nanofiber membrane according to the present invention comprises the steps of forming a nanofiber membrane by spinning a spinning solution mixed with a spinnable polymer, an iron salt precursor, and a spinning solvent, and supporting the formed nanofiber membrane in a cinnabar precursor solution to form Prussian blue crystals on the nanofiber membrane.

[0007] As a specific example, a nanofiber membrane for cesium adsorption is fabricated by forming a nanofiber membrane using an electrospinning method with a spinning solution containing a cellulose acetate solution and a Prussian flux iron salt precursor, and then immersing the nanofiber membrane in a cyanide precursor solution to crystallize Prussian blue on the surface of the nanofibers.

[0008] The present invention comprises the step of forming a nanofiber membrane by spinning a spinning solution mixed with a spinnable polymer, an iron salt precursor, and a spinning solvent;

[0009] A method for manufacturing a nanofiber membrane for cesium adsorption comprises the step of immersing the formed nanofiber membrane in a solution containing a cyanide precursor to form Prussian blue crystals on the nanofiber membrane.

[0010] In one embodiment, the spinnable polymer may be any one or more mixtures selected from the group consisting of cellulose derivatives, chitosan, alginic acid, gelatin, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyvinylpyrrolidone.

[0011] In one embodiment, the iron salt precursor may be any one or more mixtures selected from the group consisting of iron chloride (II), iron chloride (III), iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III), iron acetate (II), iron acetate (III), iron oxalate (II) and iron oxalate (III).

[0012] In one embodiment, the radiation solvent may be any one or more mixtures selected from the group consisting of dihydrolevoglucosenone, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, and acetone.

[0013] In one embodiment, the spinning solution may comprise 0.5 to 10 parts by weight of an iron salt precursor and 200 to 1000 parts by weight of a spinning solvent, based on 100 parts by weight of a spinnable polymer.

[0014] In one embodiment, the cyanide precursor may be any one or more mixtures selected from the group consisting of potassium ferrocyanide, potassium ferrocyanide, sodium ferrocyanide, sodium ferrocyanide, ammonium ferrocyanide, and ammonium ferrocyanide.

[0015] In one embodiment, the solution containing the cyanide precursor may have a concentration of 0.005 to 0.500 M of the cyanide precursor.

[0016] In one embodiment, the electrospinning may be performed at a voltage of 10 to 25 kV and a tip-to-collector distance (TCD) of 10 to 30 cm, and the spinning solution may be spun at a flow rate of 0.01 to 0.50 ml / hr.

[0017] In one embodiment, the diameter of the nanofiber membrane may be 100 to 1000 nm.

[0018] In one embodiment, the Prussian blue crystals may be formed on a nanofiber film with an average particle size of 10 to 300 nm.

[0019] In one embodiment, prior to the step of manufacturing the nanofiber membrane, the method may further include the step of preparing a spinning solution by mixing a spinnable polymer, an iron salt precursor, and a spinning solvent.

[0020] In one embodiment, the spinnable polymer may be cellulose acetate.

[0021] In one embodiment, the radiation solvent may be a mixed solvent of dihydrolevoglucosenone and acetone.

[0022] In one embodiment, the spinning solvent may be a mixture of dihydrolevoglucosenone and acetone in a weight ratio of 1 to 5:1.

[0023] Another aspect of the present invention is a nanofiber formed by spinning a spinning solution comprising cellulose acetate and an iron salt precursor; and

[0024] A nanofiber membrane for cesium adsorption is provided, comprising Prussian blue crystals crystallized and immobilized by the reaction of a cyanide precursor on the surface of the nanofiber.

[0025] In one embodiment, the nanofiber membrane for cesium adsorption may have a structure in which crystal aggregates, in which Prussian blue crystals are aggregated in a connected form, are densely bonded to the surface of the nanofiber membrane.

[0026] In one embodiment, the average particle size of the Prussian blue crystal may be 10 to 300 nm.

[0027] In one embodiment, the cesium ion adsorption capacity of the nanofiber membrane for cesium adsorption may be 50 mg / g or more.

[0028] In one embodiment, the nanofiber membrane for cesium adsorption may have a cesium adsorption amount of 80% or more after performing 10 cesium adsorption-desorption cycles relative to the initial adsorption amount.

[0029] A nanofiber membrane for cesium adsorption according to one embodiment of the present invention prevents the reduction of the active site of the membrane by ensuring that Prussian blue is not detached, and prevents environmental pollution by ensuring that Prussian blue particles are not released into the environment, such as water.

[0030] A nanofiber membrane for cesium adsorption according to one embodiment of the present invention has Prussian blue present in a crystallized form on the surface of the nanofiber membrane, so that the surface area where cesium ions come into contact with Prussian blue is maximized, thereby enabling excellent adsorption efficiency.

[0031] Figure 1 shows a nanofiber membrane for cesium adsorption according to one embodiment of the present invention observed with a electron microscope.

[0032] Figure 2 is a graph showing the adsorption efficiency of the nanofiber membrane for cesium adsorption of Example 1 of the present invention.

[0033] The present invention will be described in more detail below. However, the following specific examples or embodiments are merely references for the detailed explanation of the present invention and are not limited thereto, and the present invention may be implemented in various forms.

[0034] Furthermore, unless otherwise defined, all technical and scientific terms have the same meaning as generally understood by one of the art to which the present invention pertains. The terms used in the description of the present invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0035] Additionally, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0036] Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] Furthermore, unless otherwise specifically defined in the present invention, when a layer or member is described as being located “on” another layer or member, this includes not only cases where a layer or member is in contact with another layer or member, but also cases where another layer or member exists between two layers or two members.

[0038] Additionally, terms used herein such as “about,” “substantially,” etc., are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0039] Conventional cesium adsorbents have been reported to be manufactured by attaching Prussian blue to nanofibers after production or by mixing Prussian blue during nanofiber spinning. However, these methods suffered from issues such as the detachment of the synthesized Prussian blue or the inability to achieve sufficient cesium removal efficiency due to the small surface area of ​​the Prussian blue available for adsorbing cesium ions. To address these problems, the inventors prepared a nanofiber membrane by first incorporating an iron salt, a precursor of Prussian blue, into a spinning solution to produce nanofibers and nanofiber membranes via electrospinning, and then contacting the prepared nanofibers with a cyanide solution to ensure that the Prussian blue is uniformly crystallized and immobilized on the nanofiber surface. Through this process, the inventors invented a method for manufacturing a cesium adsorption nanofiber membrane that prevents the detachment of Prussian blue while maximizing the contact surface area between cesium ions and Prussian blue and enhancing adsorption activity.

[0040] The present invention will be described in more detail below.

[0041] The present invention comprises the step of forming a nanofiber membrane by spinning a spinning solution mixed with a spinnable polymer, an iron salt precursor, and a spinning solvent;

[0042] A method for manufacturing a nanofiber membrane for cesium adsorption comprises the step of immersing the formed nanofiber membrane in a solution containing a cyanide precursor to form Prussian blue crystals on the nanofiber membrane.

[0043] In comparison, the method of electrospinning by mixing Prussian blue itself into the spinning solution may result in Prussian blue particles not being uniformly fixed to the fiber surface during spinning, and there is a high possibility that some of the Prussian blue may be lost or irregularly distributed during the process. Additionally, the weak bonding force between the Prussian blue crystals and the nanofiber surface may lead to a decrease in cesium adsorption efficiency.

[0044] Furthermore, the method of forming a nanofiber membrane using only spinnable polymers and then attaching Prussian blue externally results in the Prussian blue being merely physically adsorbed or coated; therefore, there is a high possibility of Prussian blue detachment from the cesium adsorption nanofiber membrane, and a decrease in cesium adsorption performance may occur during long-term use.

[0045] The method for manufacturing a cesium adsorption nanofiber membrane according to the present invention may be able to significantly reduce the possibility of detachment by directly crystallizing and immobilizing Prussian blue on the nanofiber surface through a chemical reaction between an iron salt precursor and a cyanide precursor, thereby causing the Prussian blue to bind strongly to the nanofiber surface and increasing physical and chemical stability. This immobilization method may be able to maximize the contact area with cesium ions while maintaining long-term cesium removal performance.

[0046] In one embodiment, the spinnable polymer is capable of forming nanofibers by electrospinning, and is not particularly limited as long as it has good compatibility with the iron salt precursor. The spinnable polymer may be any one or more mixtures selected from the group consisting of cellulose derivatives, chitosan, alginic acid, gelatin, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyvinylpyrrolidone, but is not limited thereto.

[0047] In one embodiment, the spinnable polymer is not particularly limited but may be a cellulose derivative, such as cellulose acetate, carboxymethyl cellulose, ethyl cellulose, etc. Among these, cellulose acetate may be preferred because it has excellent mechanical strength and flexibility, enabling stable fiber formation in the electrospinning process, and has minimal physical deformation even when mixed with an iron salt precursor, but is not limited thereto.

[0048] The above-mentioned Prussian iron salt precursor is iron ions (Fe₀), which are a key component of Prussian blue. 3+ or Fe 2+ It may be a material that can react with a cyanide precursor to form a face-centered cubic lattice structure of Prussian blue.

[0049] In one embodiment, the above-mentioned Prussian blue iron salt precursor may be any one or more mixtures selected from the group consisting of iron chloride (II), iron chloride (III), iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III), iron acetate (II), iron acetate (III), iron oxalate (II) and iron oxalate (III), but is not limited to any iron salt precursor that can react with cyanide to form Prussian blue crystals.

[0050] In one embodiment, the spinning solvent is not particularly limited as long as it has good solubility for the spinnable polymer and iron salt precursor and possesses appropriate electrical conductivity to stably spin nanofibers. The spinning solvent may be any one or more mixtures selected from the group consisting of dihydrolevoglucosenone, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, and acetone, but is not limited thereto.

[0051] In one embodiment, the spinning solvent is not particularly limited, but may be, for example, a mixed solvent of dihydrolevoglucosenone and acetone. More specifically, the spinning solvent may be a mixture of dihydrolevoglucosenone and acetone in a weight ratio of 1 to 5:1, 1.5 to 4, or 2 to 3. When using the mixed solvent of dihydrolevoglucosenone and acetone, a spinning solvent satisfying the above weight ratio range is preferred, in particular, because it can effectively dissolve cellulose acetate and the spinning solution can have appropriate viscosity, thereby inducing stable and uniform fiber formation, but is not limited thereto.

[0052] The above dihydrolevoglucosenone may be the one commercially sold under the name Cyrene (Merk).

[0053] In one embodiment, the spinning solution may contain an iron salt precursor in an amount of 0.5 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less, based on 100 parts by weight of a spinnable polymer, or may contain any amount of weight between these values. For example, it may contain 0.5 to 10 parts by weight, 1 to 7 parts by weight, or 2 to 5 parts by weight. A spinning solution within the above compositional range may be advantageous for manufacturing nanofiber membranes as it can maintain a balance of appropriate viscosity and conductivity, but is not limited thereto.

[0054] In one embodiment, the spinning solution may contain a spinning solvent in an amount of 300 parts by weight or more, 400 parts by weight or more, 500 parts by weight or more, 1000 parts by weight or less, 800 parts by weight or less, or 700 parts by weight or less, with respect to 100 parts by weight of a spinnable polymer, or may contain any amount of weight between these values. For example, it may be mixed in an amount of 300 to 1000 parts by weight, 400 to 800 parts by weight, or 500 to 700 parts by weight, but is not limited thereto. Mixing the spinning solvent within the above range is preferred because it can effectively dissolve the cellulose acetate and the spinning solution can have an appropriate viscosity, thereby inducing stable and uniform fiber formation, but is not limited thereto.

[0055] The above cyanide precursor is [Fe(CN)6] 4- or [Fe(CN)6] 3- By supplying iron ions (Fe hexacyanide complexes such as 3+ or Fe 2+ It may react with ) to form Prussian blue.

[0056] In one embodiment, the cyanide precursor may be any one or more mixtures selected from the group consisting of potassium ferrocyanide, potassium ferrocyanide, sodium ferrocyanide, sodium ferrocyanide, ammonium ferrocyanide, and ammonium ferrocyanide, but is not limited thereto, and a suitable precursor may be selected according to reaction conditions to form Prussian blue.

[0057] In one embodiment, the solution containing the Prussian blue cyanide precursor may have a concentration of 0.005 M or more, 0.010 M or more, 0.020 M or more, 0.500 M or less, 0.100 M or less, or 0.050 M, and may be any value between these. For example, the concentration may be 0.005 M to 0.500 M, 0.010 to 0.100 M, or 0.020 to 0.050 M. A concentration range of the cyanide precursor is preferred because it can react uniformly with the iron ion precursor to form Prussian blue without precipitation, but is not limited thereto.

[0058] In one embodiment, the electrospinning may be performed at a voltage of 10 to 20 kV and a TCD (Tip to collector distance) of 10 to 30 cm, although this is not particularly limited, and the spinning solution may be spun at a flow rate of 0.05 to 0.5 ml / hr.

[0059] The above voltage is not specifically limited, but may be performed at, for example, 10 to 25 kV, 12 to 20 kV, or 15 to 20 kV. Electrospinning at a voltage within the above range is preferred as it prevents non-uniformity of the nanofibers or bead formation, thereby allowing for the formation of a uniform nanofiber structure, but is not limited thereto.

[0060] The above TCD is not particularly limited as long as it is capable of spinning the nanofiber of the present invention, but, for example, it may be performed at a range of 10 to 30 cm, 12 to 25 cm, or 15 to 20 cm. Performing electrospinning within the above TCD range is preferred because it can secure a stable electric field and fiber flight distance, thereby allowing the fiber to be formed stably, but it is not limited thereto.

[0061] The flow rate of the spinning solution may be determined according to the concentration, viscosity, and diameter of the nanofiber to be manufactured, and may be varied for use. For example, electrospinning may be performed at a flow rate of 0.01 to 0.50 ml / hr, 0.05 to 0.30 ml / hr, or 0.10 to 0.20 ml / hr. While performing electrospinning within the above flow rate range is preferred because it allows the Taylor cone to be well formed and stably maintained and produces uniform nanofibers, it is not limited thereto.

[0062] In one embodiment, the diameter of the nanofiber membrane may be 100 nm or more, 150 nm or more, 200 nm or more, 1000 nm or less, 800 nm or less, or 500 nm or less, and may be any value between these. For example, it may be 100 to 1000 nm, 150 to 800 nm, or 200 to 500 nm. A nanofiber membrane with the above diameter range is preferred because it can have excellent specific surface area and physical stability at the same time, and when Prussian blue crystals are formed on the surface, the surface area is maximized and the cesium removal ability can be further improved, but it is not limited thereto.

[0063] In one embodiment, the average particle size of the Prussian blue crystal is not specifically limited to a lower limit of 300 nm or less, 200 nm or less, or 150 nm or less, but may be 10 nm or more, 20 nm or more, or 50 nm or more, or any value between these. For example, it may be 10 to 300 nm, 20 to 200 nm, or 50 to 150 nm. The above average particle size range is preferred because it can have an excellent cesium adsorption capacity when the Prussian blue forms crystals on a nanofiber membrane, but it is not limited thereto.

[0064] In one embodiment, prior to the step of manufacturing the nanofiber membrane, the method may further include the step of preparing a spinning solution by mixing a spinnable polymer, an iron salt precursor, and a spinning solvent.

[0065] Another aspect of the present invention is a nanofiber formed by spinning a spinning solution comprising cellulose acetate and an iron salt precursor; and

[0066] A nanofiber membrane for cesium adsorption is provided, comprising Prussian blue crystals crystallized and immobilized by the reaction of a cyanide precursor on the surface of the nanofiber.

[0067] In one embodiment, the nanofiber membrane for cesium adsorption may have a structure in which crystal aggregates, in which Prussian blue crystals are aggregated in a connected form, are densely bonded to the surface of the nanofiber membrane.

[0068] Figure 1 shows the surface of a nanofiber membrane for cesium adsorption, in which Prussian blue crystals are densely distributed on the nanofiber surface. This structure may improve adsorption efficiency by maximizing the contact area with cesium ions. Additionally, the bonded crystals are stably fixed to the nanofiber surface, maintaining structural consistency and preventing Prussian blue from detaching from the nanofiber.

[0069] In one embodiment, the cesium ion adsorption amount of the cesium adsorption nanofiber membrane may be 50 mg / g or more, 60 mg / g or more, 70 mg / g or more, 80 mg / g or more, and, although the upper limit is not specifically limited, 500 mg / g or less, 400 mg / g or less, 300 mg / g or less, 200 mg / g or less, and may be any value between these. For example, it may be 50 to 500 mg / g, 60 to 400 mg / g, 70 to 300 mg / g, or 80 to 200 mg / g. A cesium adsorption nanofiber membrane having a cesium ion adsorption amount within the above range may be preferred as it can have excellent efficiency when applied to a cesium removal process, but it is not limited thereto.

[0070] In one embodiment, the cesium adsorption nanofiber membrane may have a cesium adsorption amount of 80% or more, 85% or more, 90% or more, 100% or less, 99% or less, or 98% or less, with no specific upper limit, relative to the initial adsorption amount after 10 cesium adsorption-desorption cycles, or any value between these. For example, it may be 80 to 100%, 85 to 99%, or 90 to 98%, but is not limited thereto. Maintaining the cesium adsorption amount within the above range after 10 cesium adsorption-desorption cycles may result in less desorption of Prussian blue from the cesium adsorption nanofiber membrane, and may be preferred as it allows for the maintenance of cesium removal efficiency over the long term rather than as a one-time measure.

[0071] In one embodiment, the cesium ion adsorption efficiency of 100 mg of the cesium adsorption nanofiber membrane may be 75% or more, 80% or more, 85% or more, 95% or less, 93% or less, or 90% or less, although the upper limit is not specifically limited, and may be any value between these. For example, it may be 75 to 95%, 80 to 93%, or 85 to 90%, but is not limited thereto. A cesium adsorption nanofiber membrane having an adsorption efficiency within the above range is preferred because it can effectively remove cesium, but is not limited thereto.

[0072] In one embodiment, the cesium ion adsorption efficiency of 200 mg of the cesium adsorption nanofiber membrane may be 80% or more, 85% or more, 90% or more, 99% or less, 98% or less, 97% or less, although the upper limit is not specifically limited, and may be any value between these. For example, it may be 80 to 99%, 85 to 98%, or 90 to 97%, but is not limited thereto. A cesium adsorption nanofiber membrane having an adsorption efficiency within the above range is preferred as it can effectively remove cesium, but is not limited thereto.

[0073] In one embodiment, the cesium ion adsorption efficiency of 400 mg of the cesium adsorption nanofiber membrane may be 95% or more, 96% or more, 97% or more, 100% or less, 99% or less, with no specific upper limit, and may be any value between these. For example, it may be 95 to 100%, 96 to 99%, or 97 to 99%, but is not limited thereto. A cesium adsorption nanofiber membrane having an adsorption efficiency within the above range is preferred as it can effectively remove cesium, but is not limited thereto.

[0074] The present invention will be explained in more detail below based on the following examples and comparative examples. However, the following examples and comparative examples are merely illustrative of the present invention and are not intended to limit the present invention.

[0075] [measurement method]

[0076] 1. Method for measuring the average diameter of a nanofiber membrane

[0077] The diameter of the fabricated nanofiber membranes was measured using a scanning electron microscope (Quattro S; Thermo Scientific). The diameters of 20 nanofiber membranes were measured, and the average value was calculated and is shown in Table 1 below.

[0078] 2. Method for Measuring the Average Particle Size of Prussian Blue Crystals

[0079] The average particle size of Prussian blue crystals formed on a nanofiber membrane for cesium adsorption was measured using a scanning electron microscope (Quattro S; Thermo Scientific) and the average value is shown in Table 1 below.

[0080] 3. Measurement of the average pore size of nanofiber membranes for cesium adsorption

[0081] After immersing the cesium adsorption nanofiber membrane in Porefil solution to wet the pores, the average pore size was measured using a capillary flow porometer (Porolux 1000, Porometer Co.), and the results are shown in Table 1 below.

[0082] 3. Method for Measuring Cesium Ion Adsorption Capacity of Nanofiber Membranes for Cesium Adsorption

[0083] 40 mg of a cesium adsorption nanofiber membrane was immersed in 20 ml of a 10 ppm CsCl aqueous solution and stirred for 15 minutes to proceed with adsorption. After adsorption, the Cs ion concentration of the residual solution was measured using ICP-MS (X Series, Thermo Fichser Scientific). The measured cesium ion adsorption amount, expressed as the cesium adsorption amount per unit mass of the cesium adsorption nanofiber membrane, is shown in Table 1 below.

[0084] 4. Method for Measuring Cesium Ion Adsorption Efficiency According to Input Amount of Nanofiber Membrane for Cesium Adsorption

[0085] Each of the cesium adsorption nanofiber membrane samples was loaded with 10 to 500 mg of cesium adsorption nanofiber membrane samples in 10 ml of a 100 ppm CsCl aqueous solution, and the Cs ion concentration of the residual solution after adsorption was measured using ICP-MS (X Series, Thermo Fichser Scientific). The measured adsorption efficiency is shown in Figure 2.

[0086] 5. Measurement of adsorption retention rate

[0087] A nanofiber membrane for cesium adsorption was immersed in 10 ml of a 100 ppm CsCl aqueous solution, and the adsorption amount was measured using the same method as described above for measuring cesium ion adsorption. Subsequently, the adsorbed cesium ions were desorbed by immersion and stirring in a 0.1 M NH4Cl solution at pH 2 for 2 hours. Afterward, re-adsorption was performed using the same method, and the adsorption-desorption cycle was repeated 10 times to check the change in the adsorbed amount relative to the initial adsorbed amount. The calculated adsorption retention rate is shown in Table 1 below.

[0088] [Example 1]

[0089] 1. Preparation of spinning solution and formation of nanofiber membrane

[0090] A spinning solution was prepared by mixing and dissolving 13.5 wt% of cellulose acetate, 86.5 wt% of a spinning solvent consisting of dihydrolevoglucosenone (Cyrene; Merk) and acetone in a 2:1 ratio, and then mixing in an iron Fe(NO3)3 salt precursor to make the solution 0.15 M.

[0091] A nanofiber membrane was prepared by electrospinning the above spinning solution at a voltage of 18 kV, a 27 G needle, an injection rate of 0.1 ml / h, a TCD of 18 cm, and a collector rotation speed of 300 rpm.

[0092] 2. Formation of Prussian blue crystals

[0093] A cyanide precursor solution was prepared by adding 0.1 M hydrochloric acid to a 0.0025 M potassium ferrocyanide solution to adjust the pH to 1 and stirring for 24 hours. The prepared nanofiber membrane was immersed in the cyanide precursor solution and stirred for 15 minutes to crystallize and immobilize Prussian blue on the nanofiber membrane. Subsequently, the nanofiber membrane for cesium adsorption was prepared by drying in a vacuum oven at 90 ℃ for 24 hours.

[0094] [Example 2]

[0095] A nanofiber membrane for cesium adsorption was prepared in the same manner as in Example 1, except that 15 wt% cellulose acetate and 85 wt% spinning solvent were used in Example 1.

[0096] Nanofiber membrane diameter (nm) Average pore size (um) Prussian blue crystal average particle size (nm) Cesium ion adsorption amount (mg / g) Adsorption amount retention rate (%) Example 1 3 200 0.75 80 80.6490 Example 2 3 80 1.25 80 13 3.8691

[0097] In Table 1 above, it was confirmed that the nanofiber membrane for cesium adsorption maintained its adsorption performance even in repeated adsorption-desorption tests with Prussian blue not easily detached, with the adsorption retention rate of the examples being over 90% after 10 cycles.

[0098] As described above, the present invention has been explained by specific details and limited embodiments; however, this is provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

[0099] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention.

Claims

1. A step of forming a nanofiber membrane by spinning a spinning solution mixed with a spinnable polymer, an iron salt precursor, and a spinning solvent; A method for manufacturing a nanofiber membrane for cesium adsorption, comprising the step of immersing the formed nanofiber membrane in a solution containing a cyanide precursor to form Prussian blue crystals on the nanofiber membrane.

2. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the above-mentioned spinnable polymer is one or more mixtures selected from the group consisting of cellulose derivatives, chitosan, alginic acid, gelatin, polyvinyl alcohol, polyacrylonitrile, polyurethane, and polyvinyl pyrrolidone.

3. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the iron salt precursor is one or more mixtures selected from the group consisting of iron chloride (II), iron chloride (III), iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III), iron acetate (II), iron acetate (III), iron oxalate (II) and iron oxalate (III).

4. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the above-mentioned spinning solvent is one or more mixtures selected from the group consisting of dihydrolevoglucosenone, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, and acetone.

5. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the spinning solution comprises 0.5 to 10 parts by weight of an iron salt precursor and 200 to 1000 parts by weight of a spinning solvent, based on 100 parts by weight of a spinnable polymer.

6. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the cyanide precursor is one or more mixtures selected from the group consisting of potassium ferrocyanide, potassium ferrocyanide, sodium ferrocyanide, sodium ferrocyanide, ammonium ferrocyanide, and ammonium ferrocyanide.

7. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the solution containing the above-mentioned cyanide precursor has a concentration of 0.005 to 0.500 M of the cyanide precursor.

8. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the electrospinning is performed at a voltage of 10 to 25 kV and a tip-to-collector distance (TCD) of 10 to 30 cm, and the spinning solution is spun at a flow rate of 0.01 to 0.50 ml / hr.

9. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the diameter of the nanofiber membrane is 100 to 1000 nm.

10. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the above-mentioned Prussian blue crystals are formed on a nanofiber membrane with an average particle size of 10 to 300 nm.

11. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, further comprising the step of preparing a spinning solution by mixing a spinnable polymer, an iron salt precursor, and a spinning solvent before the step of manufacturing the nanofiber membrane.

12. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption in which the above-mentioned spinnable polymer is cellulose acetate.

13. In Paragraph 1, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the above-mentioned spinning solvent is a mixed solvent of dihydrolevoglucosenone and acetone.

14. In Paragraph 13, A method for manufacturing a nanofiber membrane for cesium adsorption, wherein the above-mentioned spinning solvent is a mixture of dihydrolevoglucosenone and acetone in a weight ratio of 1 to 5:

1.

15. Nanofibers formed by spinning a spinning solution containing cellulose acetate and an iron salt precursor; and A nanofiber membrane for cesium adsorption comprising: Prussian blue crystals crystallized and immobilized by the reaction of a cyanide precursor on the surface of the nanofiber.

16. In Paragraph 15, The above-mentioned nanofiber membrane for cesium adsorption is a nanofiber membrane for cesium adsorption having a structure in which crystal aggregates, in which Prussian blue crystals are aggregated in a form connected to each other, are densely bonded to the surface of the nanofiber membrane.

17. In Paragraph 15, A nanofiber membrane for cesium adsorption having an average particle size of 10 to 300 nm of the above Prussian blue crystals.

18. In Paragraph 15, A cesium adsorption nanofiber membrane having a cesium ion adsorption capacity of 50 mg / g or more.

19. In Paragraph 15, The above cesium adsorption nanofiber membrane is a cesium adsorption nanofiber membrane having a cesium adsorption amount of 80% or more after performing 10 cesium adsorption-desorption cycles relative to the initial adsorption amount.

Images