KR20170052254A

KR20170052254A - Method for preparing prussian blue/reduced graphene oxide foam composite and composite thus produced

Info

Publication number: KR20170052254A
Application number: KR1020150154486A
Authority: KR
Inventors: 장성찬; 허윤석; 노창현
Original assignee: 인하대학교 산학협력단
Priority date: 2015-11-04
Filing date: 2015-11-04
Publication date: 2017-05-12
Also published as: KR101808613B1

Abstract

The present invention relates to a method for preparing a prussian blue/reduced graphene oxide foam (PB/RGOF) composite, to a PB/RGOF composite prepared thereby, and to a method for removing radioactive cesium using the same, and more specifically, to method for preparing the PB/RGOF composite, and to the method for removing the radioactive cesium using the same, capable of effectively removing the radioactive cesium present in contaminated water by PB nanoparticles dispersed on a large surface area and inside the composite, by depositing PB nanoparticles on a GO sheet by a simple hydrothermal reaction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PB / RGOF composite and a PB / RGOF composite,

The present invention relates to a process for preparing PB / RGOF ( ¹³⁷ Cs) removal of radioactive cesium and a PB / RGOF complex prepared as described above.

Today, the development of technologies for removing harmful substances from industrial wastewater is of utmost importance in solving the shade of industrialization.

Among the various pollutants generated from industrial wastewater, cesium (Cs) is one of the most noteworthy materials recently. Cesium is a relatively rare metal, and cesium present in nature does not release harmful radiation to the human body. However, unlike cesium-133 (mass 133), which is present in nature, cesium-135 (mass 135) and cesium-137 (mass 137) released during nuclear fission or nuclear fission are substances with radioactivity harmful to human body. The cesium-135 and cesium-137 are inevitably generated when a nuclear power plant fissures uranium or plutonium into neutrons.

(Half-life of 2.3 million years), cesium-137 (half-life of 30 years), and strontium (a half-life period of 30 years) as radioactive fission products, which have long been dangerous to the environment when nuclear energy is generated by nuclear fission from uranium, (Sr) -90 (half-life period of 28.9 years). They are known to account for 6.9% of cesium-135, 6.3% of cesium-137, and 4.5% of strontium, respectively, in fission products.

Recently, a substance frequently mentioned in connection with the accident in Fukushima nuclear power plant in Japan is the pollution problem of cesium (Cs). The risk of cesium (Cs) is primarily a radioactive hazard due to the fission product cesium-137. Since the half-life of cesium-135 is about 2.3 million years, the amount of radiation emitted per hour is actually small, so that the risk is much lower than that of cesium-137. Cesium-137, which belongs to a radioactive substance, is an ion, or a compound, which continuously emits radiation. Therefore, it is most important to completely remove it. As with other radioactive materials, exposure to cesium-137 radiation increases the risk of cancer.

The presence of radioactive Cs-137 and Cs-135 in aqueous solution may not only destroy the environment but also have a significant impact on human health. Moreover, since cesium ions are chemically similar to potassium ions, they can easily combine with land and aquatic organisms. When cesium ions accumulate in the human body through groundwater, fish, or shellfish, they can destroy the tissues of the body and, in severe cases, can cause cancer of the thyroid gland. Particularly, there is an increasing demand for effective and efficient removal of cesium (Cs) with increasing interest in radioactive materials.

To remove cesium (Cs), methods such as precipitation method, liquid-liquid extraction method, ion exchange method using organic ion exchanger, and chromatography method have been developed. Of these methods, the ion exchange method has attracted a lot of attention in recent years because of its advantages such as simplicity of application, efficiency, and selectivity.

However, since the method developed by the ion exchange method uses an expensive organic synthetic ion exchange resin, the maintenance cost is increased due to frequent replacement of the ion exchange resin and a decrease in mechanical strength. In order to massively remove the cesium, There is a problem that the size of the exchange facility must be increased.

On the other hand, as a method for removing heavy metal pollutants in industrial wastewater, there is a method using inorganic materials such as zeolite, sodium titanate, silicotitanates, metal oxides and the like. The inorganic material has an advantage of excellent thermal stability and durability, but it is not effective in removing cesium.

On the other hand, recently, several new adsorbents have been developed to reduce the concentration of radioactive metal ions in contaminated aqueous solutions and have been used in the past few years. These include self-adsorption, biocomposites, nanocomposites and organometallic flame reactions. Among these materials, biocomposites produced from natural resources are the most promising materials for the removal of various toxic pollutants in aqueous solutions and are environmentally friendly. Therefore, technological development and technological development that can reduce operating costs are urgently required .

If it is possible to efficiently adsorb and remove harmful radioactive cesium from contaminated wastewater, it will achieve significant technological advances in terms of environmental engineering, while reducing the amount of cesium (concentration) It will build a foundation for However, even though there is such a real necessity and necessity, there is no such technology development yet.

Japanese Laid-Open Patent Publication No. 2015-104722

In order to solve the problems of the prior art as described above, the present invention provides a method of depositing PB nanoparticles on a GO sheet by a simple hydrothermal reaction, thereby effectively removing radioactive cesium by PB nanoparticles dispersed in a complex with a large surface area PB / RGOF (prussian blue / reduced graphene oxide foam) composite, and a PB / RGOF composite prepared as described above.

The present invention also relates to a method of producing a PB / RGOF composite capable of effectively adsorbing and removing cesium present in contaminated water due to ion exchange characteristics of graphene foam and prussian blue, And a method for removing radioactive cesium using the same.

In order to achieve the above object, the present invention relates to (S1) an α-FeOOH / GO solution in which α-FeOOH nanoparticles are deposited on a GO surface by adding FeSO ₄ to a graphene oxide (GO) Producing; (S2) adding K ₄ [Fe (CN) ₆ ] to the α-FeOOH / GO solution of step (S1) to form PB (prussian blue, Fe ₄ [Fe (CN) ₆ ]) nanoparticles; And (S3) hydrothermally reacting the reactant in the step (S2). The present invention also provides a method for preparing a PB / RGOF (Prussian blue / reduced graphene oxide foam) composite.

After the hydrolysis of the (S1) is a step to adjust the pH of the suspension to the GO 2-4 may be carried out by the addition of FeSO _4. At this time, the FeSO ₄ is preferably added to the GO suspension in an amount of 0.5 to 5 mmol, and FeSO _{4 is} added, followed by hydrolysis at room temperature for 60 to 120 seconds.

It is preferable to add K ₄ [Fe (CN) ₆ ] of the step (S2) to the α-FeOOH / GO solution at 10 to 20 mM, and the reaction is preferably carried out under an acidic condition (pH 3).

The hydrothermal reaction in step (S3) is preferably performed at 150 to 200 ° C for 10 to 15 hours.

The present invention also provides a PB / RGOF composite which is prepared by the above-described method, wherein prussian blue is deposited on the oxide graphene and a porous graphene network is formed on the outside.

The present invention also provides an adsorbent for removing radioactive cesium ( ¹³⁷ Cs), which comprises the PB / RGOF complex.

The present invention also provides a method for removing radioactive cesium ( ¹³⁷ Cs) using the adsorbent for removing radioactive cesium.

According to the present invention, by depositing PB nanoparticles on a GO sheet by a simple hydrothermal reaction, the PB nanoparticles dispersed in the composite and the large surface area have a high adsorption capacity, effectively adsorbing cesium present in the contaminated water Can be removed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a method for producing a PB / RGOF composite according to the present invention. FIG.
2 is an optical, SEM, and TME image of a PB / RGOF composite prepared according to an embodiment of the present invention. Fig. 2A shows an optical image of the composite, Figs. 2B and 2C show a SEM photograph of the composite, and Fig. 2D shows a TEM photograph of the composite.
Figure 3 shows the FT-IR spectra (a), XRD pattern (b), Raman spectrum (c) and N ₂ adsorption / desorption isotherms (d) of the PB / RGOF complex and GO prepared according to one embodiment of the present invention Fig.
FIG. 4 shows XPS results of PB / RGOF composite and GO prepared according to one embodiment of the present invention.
FIG. 5 is a graph showing adsorption experiments on cesium by the Langmuir and Freundlich model equations of the PB / RGOF composite prepared according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

In the present invention, the PB / RGOF complex in the form of 3D foamed hydrogel was prepared by depositing prussian blue (PB) nanoparticles on the surface of reduced graphene oxide foam (RGOF) by a simple hydrothermal method.

In the present invention, PB refers to prussian blue (Fe ₄ [Fe (CN) ₆ ]), GO denotes graphene oxide, and RGOF denotes graphene oxide Quot; refers to reduced graphene oxide foam.

The production method of the PB / RGOF composite of the present invention will be described in detail as follows.

(S1) Production of α-FeOOH / GO solution

First, GO suspension is prepared by dispersing in water because of strong hydrophilicity and electrostatic repulsion of GO. At this time, the GO suspension is prepared by dispersing GO in DI water at a concentration of 3.0 to 4.0 mg / mL, preferably 3.5 mg / mL. At this time, it is preferable that the GO concentration is 3.0 to 4.0 mg / mL because the 3D structure is difficult to produce when the GO concentration is out of the above range.

In order to uniformly disperse the GO in pure water, ultrasonic treatment may be performed, and the ultrasonic treatment may be performed for about 1 hour.

Subsequently, hydrochloric acid (HCl) is added to adjust the pH of the suspension to acidic pH for the PB deposition on the GO surface so that the pH is 2 to 4, preferably 3.

When the pH of the GO suspension is 2 to 4, FeSO ₄ is added. After addition of FeSO ₄ , stirring is carried out vigorously. Iron ions (Fe ²⁺ ) tend to diffuse through the electrostatic interactions into the GO sheet, which causes hydrolysis of the α-FeOOH nanoparticles by the oxygen contained in the functional groups present in the GO, Fe ²⁺ ). That is, the Fe ²⁺ ions formed from FeSO 4 added in this step are oxidized to Fe ³⁺ ions by the oxygen present in the GO, and the hydrolysis reaction at the site of the oxygen contained in the functional groups present in the GO results in α- FeOOH nanoparticles are deposited to form α-FeOOH / GO. At this time, the α-FeOOH nanoparticles have an average size of about 300 nm and an elliptical shape.

The hydrolysis reaction is preferably performed at room temperature for 60 to 120 seconds.

(S2) PB (Fe ₄ [Fe (CN) ₆ ]) nanoparticle formation

K ₄ [Fe (CN) ₆ ] is added dropwise to the α-FeOOH / GO solution prepared in the above step.

At this time, while K ₄ [Fe (CN) ₆ ] is added, the reaction mixture is continuously stirred until the color of the reaction mixture turns from black representing the formation of PB nanoparticles to dark blue.

In this step, since Fe 3+ can preferentially react with the hexacyano iron ion which is generated near the surface of the GO, it is preferable to carry out the reaction at the acidic condition, preferably pH 3, in order to improve the PB deposition on the GO surface .

(S3) Preparation of PB / RGOF complex

After the formation of the PB nanoparticles in the above step, the reaction product is hydrothermally reacted.

That is, in this step, the hydrothermal reaction is performed so that the GO is self-assembled into the hydrogel of the network structure bonded by the hydrogen and the π-π superposition.

The hydrothermal reaction is preferably carried out at 150 to 200 ° C for 10 to 15 hours, preferably at 180 ° C for 12 hours. If the reaction temperature is lower than 150 ° C, the strength of the structure of the 3D structure may be weak. If the temperature exceeds 200 ° C, safety of the reactor may be deteriorated. When the reaction time is less than 10 hours, the structure of the 3D structure may not be completely formed.

After the hydrothermal reaction, the prepared PB / RGOF complex is separated, washed several times with distilled water, and lyophilized (-80 ° C., 12 hours) to obtain a PB / RGOF complex.

The PB / RGOF composite of the present invention manufactured as described above has a 3D network structure formed by uniformly dispersing various fine pores on the outside, and a cubic PB nanoparticle having a uniform size of about 50 nm on the RGOF surface In the form of a 3D foamed hydrogel.

The present invention also provides an adsorbent for removing radioactive cesium ( ¹³⁷ Cs) containing the PB / RGOF complex prepared as described above and a method for removing radioactive cesium using the same.

It is needless to say that the method of removing radioactive cesium using a cesium adsorbent containing the PB / RGOF complex may be removed according to a conventional method in the art.

The cesium adsorbent containing the PB / RGOF complex is charged into the radioactive water contaminated with radioactive cesium and the radioactive cesium is removed by the adsorption performance of the cesium adsorbent containing the PB / RGOF complex, Cesium can be removed.

Hereinafter, the present invention will be described in more detail with reference to examples. These embodiments are for purposes of illustration only and are not intended to limit the scope of protection of the present invention.

Material preparation

The compounds used in the following examples were prepared as follows.

The graphite powder, K ₂ S ₂ O ₈ , P ₂ O ₅ , KMnO ₄ , FeSO ₄ , K ₄ [Fe (CN) ₆ ], H ₂ SO ₄ and HCl were purchased from Sigma Aldrich Respectively. An inactive Cs solution (KANTO Chemical Co. Inc.) and radioactive Cs ( ¹³⁷ Cs) were obtained from the Korea Atomic Energy Research Institute (KAERI). All compounds were used without further purification.

Example 1. Preparation of PB / RGOF complex

GO was prepared by chemical stripping of graphene powder according to the modified Hummer's method. A GO suspension was prepared by dispersing 70 mg of GO in 20 mL of water. To the GO suspension, hydrochloric acid (HCl) was added to adjust the pH to 3, and then 1 mmol of FeSO ₄ was added with stirring. At this time, Fe ²⁺ of FeSO ₄ was oxidized to Fe ³⁺ by hydrolysis to form α-FeOOH nanoparticles. Next, ₁₀ mM K ₄ [Fe (CN) ₆ ] was added to the reaction mixture and stirring was continued for a time period during which the color of the mixture changed from black to dark blue (indicating formation of PB nanoparticles). The resulting reaction mixture was then transferred to a Teflon-lined reactor and subjected to hydrothermal reaction at 180 ° C for 12 hours. The PB / RGOF complex thus obtained was separated, centrifuged and washed several times with distilled water. Finally, the final PB / RGOF was obtained by lyophilization at -80 ° C for 12 hours.

Figure 1 is a simplified road, Figure 1a illustrates a method of manufacturing a PB / RGOF composite of the present invention the GO, Figure 1b is α-FeOOH is formed by the addition of FeSO ₄ in GO suspension / GO, Figure 1c K ₄ [ Fe (CN) ₆ ] and the PB / RGOF complex formed by the hydrothermal reaction.

Example 2. Characterization of PB / RGOF complex

The PB / RGOF composite prepared in Example 1 was observed by the following method.

Scanning electron microscopy (SEM) images were taken using an S-4800SE microscope at an accelerating voltage of 15 kV. The FT-IR spectrum was measured using JASCO FT / IR-6600. XRD diffraction analysis was performed using a Bruker D2 phaser (Germany) diffractometer with Cu Kα radiation. The pore size distribution was measured using a full automatic physical adsorption analyzer (ASAP 2020 TriStar). XPS measurements were made using a k-alpha electron spectrometer (Thermo Scientific). Raman spectra were measured using a 532 nm laser Raman microscope (UniRAM, UniNanoTech., Korea). Inductively coupled plasma mass spectrometry (ICP-MS) was measured using Perkin Elmer ELAN6100, and the activity of radioactive cesium was measured using an HPGe detector (Canberra, USA).

2 is an optical, SEM, TEM image of the PB / RGOF composite of Example 1. FIG. FIG. 2A shows an optical image of the PB / RGOF composite of Example 1 after lyophilization for one day, and FIG. 2B shows an SEM photograph of the PB / RGOF composite, wherein the composite after freeze- It can be seen from FIG. 2C that a plurality of cubic PB nanoparticles having a uniform size (50 nm) are deposited on the RGOF surface. FIG. 2d shows the TEM photograph of the PB nanoparticles on the RGOF and the EDS spectrum. As a result of the EDS mapping analysis, the presence of C, Fe and N on the PB / RGOF composite was confirmed. And that the PB nanoparticles were successfully deposited on the substrate.

3A shows the FT-IR spectrum of the PB / RGOF complex prepared in Example 1 and GO. The GO spectrum showed an adsorption band at 1733 cm ^-1 , which corresponds to the carboxyl C = O stretching vibration. 3382 cm ^-1 corresponds to OH stretching vibration. The adsorption bands at 1615 cm ^-1 , 1400 cm ^-1 and 1052 cm ^-1 correspond to the aromatic C = C, C-OH, and epoxy CO stretching vibrations, respectively. On the other hand, in the case of PB / RGOF composites, the C = O, OH and CO bands decreased with the reduction of GO to RGO. Thus, the three vibration bands located at 2082 cm ^-1 , 570 cm ^-1 and 490 cm ^-1 are due to the stretching vibrations of Fe-CN, Fe-O and Fe ²⁺ -CN-Fe ³⁺ , respectively. The 2082 cm ^-1 band is due to the presence of the a-CN group.

FIG. 3B shows the XRD pattern of the PB / RGOF composite and the GO prepared in Example 1. FIG. In GO, the sharp diffraction peaks observed at 10.4 deg. Correspond to (002) planes. In the XRD spectrum of the PB / RGOF complex, all peaks corresponded to PB and RGO. The diffraction peaks were observed at 2θ = 17.4 °, 24.8 °, 35.3 ° and 39.5 ° corresponding to (200), (220), (222) and (400) of the face-centered cubic structure of PB nanoparticles. The (002) plane of the graphitic carbon overlapped the (220) plane of the PB.

FIG. 3C shows Raman spectra of the PB / RGOF complex prepared in Example 1 and GO. In the GO, two noticeable bands, D and G, were observed at 1310 and 1590 cm ^-1 , respectively. As a G band corresponding to the contact CC stretching vibration, the G band represents an amorphous carbon which appears as a structural bond. On the other hand, the D and G bands of the complex shifted slightly. In addition, the presence of PB nanoparticles from characteristic bands at 195, 386 and 588 cm <" ¹ > The intensity ratio of D band (ID / IG) to G band in PB / RGOF complex (1.079) was higher than GO (0.996). These results demonstrate the formation of a new graphite domain, that is, the GO is reduced to RGO after hydrothermal reaction.

FIG. 3D is a graph showing the texture characteristics of the RGOF and PB / RGOF complexes prepared in Example 1 by using Brunauer-Emmett-Teller (BET). It was confirmed that the surface area (43.07 m 2 / g) of the PB / RGOF composite was slightly smaller than the RGOF (345.24 m 2 / g) through the N ₂ adsorption / desorption isotherm shown in FIG. The pore sizes of the RGOF and PB / RGOF composites were found to be in the range of 2 to 10 nm and 2 to 5 nm, respectively.

FIG. 4 shows XPS results of the PB / RGOF composite prepared in Example 1 and GO. The sharp peak in Figure 4A indicates the presence of carbon and oxygen elements in the RGOF. Also in FIG. 4b, C1s (284.4), O1s (531.4), N1s (397.1) and Fe2p (710.8eV) peaks were observed to confirm that PB was successfully deposited on the RGOF surface. Figure 4c shows the core-level spectra of the GO powder, showing non-oxygen C = C (284.8 eV) and CC (285.5 eV), CO (286.9 eV), C = O (287.8 eV) and OC = O . FIG. 4d shows the C1s spectrum of the PB / RGOF complex. The peak intensities of CO, C = O and OC = O were significantly reduced compared to GO, indicating that GO reduction to RGO was successful through hydrothermal processing. The core-level spectra of N1s showed peaks at 401.9, 399.8 and 397.5 eV, confirming the presence of -C≡N of the complex (Fig. 4e). In the Fe2p spectrum, peaks for Fe indicating? -FeOOH were observed at 710.8 and 724.1 eV (Fig. 3f). The peak at 708.1 eV is due to [Fe (CN) ₆ ].

Example 3. Adsorption experiment

Using 10 mg of the PB / RGOF complex prepared in Example 1 above, a batch experiment was carried out in a 10 mL glass bottle containing 5 mL of cesium solution (200.69 ppb). The vial was shaken for 12 hours, then the aqueous solution was removed and passed through a syringe-type filter. Initial and residual cesium concentrations were analyzed by ICP-ms analyzer. The partition coefficient (K _d ) was defined as Equation (1) to evaluate the ability of the adsorbent to remove from the contaminated water. The experiment was repeated three times, and the average values thereof are shown in Table 1 below.

[Equation 1]

Where C ₀ and C _e represent the initial and equilibrium concentrations of cesium, V is the volume of the cesium solution and M is the mass of the adsorbent.

C ₀
(ppb) C _e
(ppb) Removal efficiency (%) K _d
(mL / g) RGOF 200.69 98.89 50.72 411.77 PB / RGOF 200.69 11.71 94.17 6455.34

As shown in Table 1, the PB / RGOF composite prepared according to the present invention had a remarkably superior cesium removal ability as compared with RGOF. From the results, it can be seen that the PB / RGOF composite of the present invention has somewhat less surface area than RGOF However, it was found that PB nanoparticles deposited on RGOF had higher cesium adsorption capacity.

Example 4. Adsorption Isotherm

Adsorption isotherms were investigated based on batch experiments. Elemental, inactive cesium was used to study adsorption behavior. The initial cesium concentration was varied from 1 to 500 ppm. 10 mg of the PB / RGOF complex prepared in Example 1 was added to 4 mL of the water-soluble cesium solution, and the mixture was shaken at 60 rpm for 12 hours in a rotary shaker. Then, the adsorbent was filtered and separated, and the cesium concentration was analyzed by ICP = MS. The results are shown in Fig.

FIG. 5 shows the results of adsorption experiments on cesium by the Langmuir and Freundlich model equations. It was confirmed that the adsorption capacity rapidly increased with increasing Cs ion concentration when the initial concentration of Cs was less than 200 ppm, Indicating that the PB / RGOF complex of the invention can be used sufficiently as a cesium adsorbent. It was also confirmed that the adsorption capacity increased slightly at a concentration of 200 ppm or higher.

The Langmuir and Freundlich adsorption isotherm models were adapted to fit equilibrium adsorption data. The Langmuir model is useful for single layer adsorption on the assumption that all binding sites are free, and the equation of nonlinear form is as shown in Equation 2 below.

&Quot; (2) "

In the above equation, q _e and q _max mean the equilibrium adsorption capacity and the single-layer maximum adsorption capacity (mg / g), respectively. K is a constant according to the relationship between the adsorbent and sorbate.

On the other hand, the Freundlich adsorption isotherm model is an empirical formula depicting multi-layer adsorption along various types of adsorption sites on the adsorbent surface.

&Quot; (3) "

Where K _F and n are Freundlich constants related to the multilayer adsorption capacity.

The variables and correlation coefficients set in the two models are shown in Table 2 below. The maximum adsorption capacity of PB./RGOF was determined to be 18.67 mg / g.

The variables and correlation coefficients for both Langmuir and Freundlich models are shown in Table 2 below.

As shown in Table 2 above, the Langmuir model and the Freundlich equation show that the isotherms of the R ² value are 0.97 and the adsorption capacity of the complex is 18.67 mg / g at the maximum.

Example 5. ¹³⁷ Measurement of decontamination ability of Cs solution

The radioactive ¹³⁷ Cs-containing solution was prepared by diluting the stock solution to about 100 Bq / g. 0.1, 0.5, and 1.0 mg / mL of the PB / RGOF complex prepared in Example 1 were dispersed in 87.49 Bq / g of the 137Cs solution. The vials were then shaken for 12 hours, filtered through a syringe filter, and the adsorption capacity was measured using a phosphor detector (Canberra, USA). ¹³⁷ Cs removal efficiency (%) and decontamination factor (DF) value can be defined by the following equations (4) and (5), and the ¹³⁷ Cs adsorption capacity of the PB / RGOF composite was evaluated. The results are shown in Table 3 below.

&Quot; (4) "

&Quot; (5) "

In the above equations (4) and (5), the initial and equilibrium concentrations of C ₀ and cerium solutions, respectively, A ₀ and A _F mean aqueous cesium radioactivity in the initial and final solution solutions after treatment, respectively.

PB / RGOF complex concentration
(mg / ml) Activity before treatment (Bq / g) After treatment (Bq / g) Removal efficiency
(%) DF 0.1 88.70 10.91 87.70 8.13 0.5 90.14 4.10 95.45 21.98 1.0 87.49 0.41 99.53 213.39

As shown in Table 3, ¹³⁷ Cs removal was 95.5% at 0.5 mg / mL of the PB / RGOF complex, which was predicted to be due to a large number of adsorption sites. In addition, ¹³⁷ Cs removal increased to 99.5% when PB / RGOF complex was increased to 1 mg / mL. It was also confirmed that the PB / RGOF complex could be applied to remove ¹³⁷ Cs from contaminated water containing ¹³⁷ Cs from high DF (> 20).

Although the present invention has been described in terms of the preferred embodiments mentioned above, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. It is also to be understood that the appended claims are intended to cover such modifications and changes as fall within the scope of the invention.

Claims

(S1) adding FeSO ₄ to a graphene oxide (GO) suspension and hydrolyzing to prepare an? -FeOOH / GO solution;
(S2) adding K ₄ [Fe (CN) ₆ ] to the α-FeOOH / GO solution of step (S1) to form PB (prussian blue, Fe ₄ [Fe (CN) ₆ ]) nanoparticles; And
(S3) hydrothermally reacting the reactant in the step (S2);
(R) < / RTI > (Prussian blue / reduced graphene oxide foam) composite.

The method according to claim 1,
After hydrolysis of the (S1) is a step to adjust the pH of the suspension to 2-4 GO method of producing a PB / RGOF composite, characterized in that is carried out by the addition of FeSO _4.

The method according to claim 1,
Wherein the FeSO ₄ in step (S1) is added to the GO suspension in an amount of 0.5 to 5 mmol.

The method according to claim 1,
Wherein the hydrolysis of step (S1) is performed at room temperature for 60 to 120 seconds.

The method according to claim 1,
Wherein the K ₄ [Fe (CN) ₆ ] of the step (S2) is added to the α-FeOOH / GO solution at 10 to 20 mM under acidic conditions.

The method according to claim 1,
Wherein the hydrothermal reaction in step (S3) is performed at 150 to 200 DEG C for 10 to 15 hours.

RGOF (prussian blue / reduced), which is prussian blue (Fe ₄ [Fe (CN) ₆ ]) deposited on graphene oxide (GO) graphene oxide foam composite.

An adsorbent for removing radioactive cesium ( ¹³⁷ Cs), which comprises the PB / RGOF complex according to claim 7.

A method for removing radioactive cesium ( ¹³⁷ Cs) using the adsorbent for removing radioactive cesium according to claim 8.