KR20230084969A - A complex comprising prussian blue or its analogs, preparing method thereof, and absorbent for ammonia or ammonium ion comprising theereof - Google Patents

Abstract

The present invention relates to a complex comprising Prussian blue (PB) or its analogue (PBA), capable of adsorbing nitrogen-containing substances, a preparing method thereof, or an adsorbent using the same. The complex can be prepared in an aqueous solvent by a simple method, and exhibits excellent adsorption performance for nitrogen-containing substances. The preparing method of the complex of the present invention comprises: a) preparing a support to which metal cation is bonded; b) forming Prussian blue (PB) or its analogue (PBA) on the support; and c) reacting alkaline metal with the Prussian blue (PB) or its analogue (PBA) formed on the support.

Description

Composite containing Prussian blue or analogues thereof, preparation method thereof, and ammonia or ammonium ion adsorbent containing the same

The present invention relates to a composite containing Prussian blue or an analogue thereof, a method for preparing the same, and an adsorbent for ammonia or ammonium ions including the same.

Organic waste is recognized as a raw material for new and renewable energy through the production of biogas through anaerobic digestion and hydrogen gas/electricity through catalytic reforming, and various components contained in organic waste are evaluated as future urban resources.

Among them, nitrogen is a key element constituting organic matter and is contained in a large amount in organic waste, but it is difficult to recover and cannot be recycled. In addition, treatment water quality standards for nitrogen, which is the cause of eutrophication, are being strengthened, but biological nitrogen treatment technology requires excessive energy consumption and increased facility capacity, and recovery is difficult.

In the biogas production process, organic matter is converted to methane, but nitrogen and phosphorus are eluted, so the digested sludge talae is characterized by a low carbon/nitrogen (C/N) ratio. In order to remove nitrogen from wastewater with a low C/N ratio, an external carbon source must be injected and excessive energy consumption for nitrification of nitrogen components is required, so high-concentration nitrogen generated in the biogas production process can be efficiently removed. technology development is needed.

On the other hand, Prussian Blue (PB) or its analog (Prussian Blue Analog, PBA) is well known as a type of porous coordination polymer (PCP). PB or PBA is characterized by a simple cubic structure with linear bridges of octahedaral metal ions by cyanide anions. In this cubic structure, pores in which ions can exist exist. The voids include interstitial sites and vacancy sites. Due to these pore characteristics, PB or PBA is attracting attention in various fields such as gas separation, adsorption, catalysis, and molecular sensing.

In particular, it is known that PB or PBA adsorb cesium or ammonia. However, when PB or PBA is synthesized into nano- or micro-sized particles, its utilization in the water treatment field is limited. In addition, there is a need for an adsorbent having better adsorption performance.

Korean Registered Patent No. 10-2126454 Japanese Laid-open Patent No. 2019-017796

An object of the present invention is to solve the problems and technical problems of the prior art as described above.

The present invention is a composite that can be used in the field of water treatment, can be manufactured by a simple manufacturing process, and has excellent selective adsorption capacity for ammonia or ammonium ions, a manufacturing method thereof, an adsorbent including the same, and a method for capturing ammonia or ammonium ions using the same provides

The term PB or PBA used in the present invention includes a metal cation and a cyano group (anion, CN ^- ) that is a ligand for crosslinking these metal cations. More specifically, PB or PBA is a series of compounds called metal cyano complexes that structurally have hexacyano (HC) and metal ions. The PB or PBA has the following general formula (1).

[Formula 1]

A _x M _a [M _b (CN) ₆ ] _y ㆍ _z H ₂ O

in the above formula

A represents one or more cations selected from the group consisting of hydrogen, lithium, ammonium, sodium, potassium, rubidium, and cesium, preferably sodium or potassium, more preferably potassium,

M _a is one or more metal cations selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, europium, gadolinium, lutetium, barium, strontium and calcium; Represents, preferably selected from the group consisting of iron, cobalt, nickel, copper and zinc,

M _b represents one or more metal cations selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum and copper, preferably selected from iron or cobalt;

x represents a number from 0 to 3, y from 0.1 to 1.5, and z from 0 to 6.

PB or PBA has a nanoporous structure capable of bringing adsorbed substances therein. The nanopore structure is about 0.5 nm in size and has a very large surface area because it is regularly interwoven.

The combination of metal ions M _a and M _b is not particularly limited, but M _a is selected from the group consisting of iron, cobalt, nickel, copper and zinc, and M _b may be selected from iron or cobalt. Representative combinations of M _a and M _b are M _a =Fe ³⁺ and M _b =Fe ²⁺ , M _a =Cu ²⁺ and M _b =Fe ²⁺ , M _a =Zn ²⁺ and M _b =Co ³ , M _a =Co ²⁺ and M _b =Co ³⁺ , or M _a =Zn ²⁺ and M _b =Fe ²⁺ .

The present invention comprises the steps of a) preparing a metal cation-bound support by reacting a metal cation precursor with a support having a functional group capable of bonding with the metal cation;

b) reacting a metal cyanide compound with a metal cation bound to the support to form Prussian blue (PB) or an analog thereof (PBA) on the support; and

c) a method for producing a composite comprising Prussian blue or an analog thereof, comprising the step of reacting an alkali metal with Prussian blue or an analog thereof formed on the support.

In step a), the metal cation is not particularly limited, but may be one selected from the group consisting of iron, cobalt, nickel, copper, and zinc.

In addition, metal cation precursors include oxides, chlorides, bromides, fluorides, and iodides of metal cations; acetide; nitric oxide; sulfur oxides; perchlorate; carbonylates; thiolate; fatty acid salts of saturated or unsaturated carbon chains; and phosphonates; One or more selected from may be used, but is not limited thereto, and for example, chloride, nitride or sulfur oxide may be used.

In the above method, the functional group capable of bonding with the metal cation may be used without limitation as long as it is a functional group capable of ionic bonding or coordination bonding with the metal cation, but may be, for example, -COO- ^, -SO ₃ ^- , or a ligand.

The support having a functional group capable of bonding with a metal cation is not particularly limited, but a cation exchange resin may be used.

Cation exchange resins are classified into strong acidic cation exchange resins and weakly acidic cation exchange resins according to functional groups, and classified into gel-type resins and porous-type resins according to manufacturing methods, and these can be used without limitation in the present invention. .

The strong acid cation exchange resin is the most widely used cation resin, and there are H type having a sulfonic acid group (-SO ₃ H) as an exchange group and Na type having a sulfonate (SO ₃ Na) exchange group. is a copolymer of styrene and divinylbenzene. In addition, weakly acidic cation exchange resins having a carboxyl group (-COOH) as an exchange group are mainly used.

Reaction conditions in step a) of reacting the metal cation precursor with a support having a functional group capable of binding to the metal cation are not particularly limited. The reaction of the metal cation precursor and the support may proceed in an aqueous solvent, for example water, for 10 hours to 36 hours. The reaction temperature and pressure are not particularly limited, and may be carried out, for example, at room temperature and pressure.

In step a), a step of removing unreacted precursors and the like by washing with sufficient water after the metal cations are adsorbed on the support may be further included.

In the method of the present invention, step b) is a step of forming Prussian blue or an analog thereof on a support by reacting a metal cyanide compound with a metal cation bonded to the support.

The metal cyanide compound is a compound including a unit in which a hexacyanide (HC) ligand is coordinated with a metal. Exemplary metalcyanide compounds are represented by general formula 2 below.

[Formula 2]

B _p [M(CN) ₆ ] _{q r} H ₂ O

in the above formula

B represents one or more cations selected from the group consisting of hydrogen, lithium, ammonium, sodium, potassium, rubidium, and cesium, preferably represents sodium or potassium, more preferably represents potassium,

M represents one or more metal cations selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum and copper, preferably selected from iron or cobalt;

p is 0 to 5, q is 0.1 to 1.5, and r is a numerical value of 0 to 6.

In one embodiment, in the above formula, M includes iron or cobalt, and A is a compound containing sodium or potassium, for example, Na ₄ [Fe(CN) ₆ ], Na ₃ [Co(CN) ₆ ], K ₄ [Fe(CN) ₆ ] or K ₃ [Co(CN) ₆ ] may be used, but is not limited thereto.

Reaction conditions in the step of reacting the metal cyanide compound with the metal cation bound to the support are not particularly limited. The reaction between the metal cyanide compound and the metal cation bonded to the support may be performed in an aqueous solvent, for example water, for 0.2 to 3 hours. The reaction temperature and pressure are not particularly limited, and may be carried out, for example, at room temperature and pressure.

In the above step, a step of removing unreacted compounds and the like by washing the support to which Prussian blue or its analog is bound with sufficient water after the reaction may be further included.

In the method of the present invention, step c) is a step of reacting an alkali metal with the support to which the Prussian blue or analog thereof is bonded.

The alkali metal is not particularly limited as long as it can be ion-exchanged with ammonia or ammonium ions adsorbed on the complex. For example, the alkali metal can be one or more alkali metal ions selected from sodium or potassium.

The alkali metal ion may participate in the reaction in the form of a sodium or potassium precursor. Sodium precursor or potassium precursor is sodium acetate, sodium bicarbonate, sodium boron hydride, sodium bromate, sodium bromide, sodium carbonate, sodium chlorate, sodium chloride, sodium citrate, sodium cyanide, sodium sulfate, sodium ethoxide, sodium fluoride, sodium formate , sodium hydroxide, sodium iodide, sodium nitrate, sodium nitrite, sodium sulfate, potassium acetate, potassium bicarbonate, potassium boron hydride, potassium bromate, potassium bromide, potassium carbonate, potassium chlorate, potassium chloride, potassium citrate, potassium cyanide, potassium sulfate, At least one selected from potassium ethoxide, potassium fluoride, potassium formate, potassium hydroxide, potassium iodide, potassium nitrate, potassium nitrite, and potassium sulfate may be used, but is not limited thereto. The sodium precursor or potassium precursor may be, for example, one or more selected from sodium chloride, sodium cyanide, sodium sulfate, sodium hydroxide, sodium nitrate, sodium sulfate, potassium chloride, potassium cyanide, potassium sulfate, potassium hydroxide, potassium nitrate, or potassium sulfate. .

The reaction conditions of step c) are not particularly limited. The reaction of the sodium precursor or the potassium precursor may proceed in an aqueous solvent, for example water, for 0.2 to 3 hours. The reaction temperature and pressure are not particularly limited, and may be carried out, for example, at room temperature and pressure.

The final product of the above step may contain more sodium ions or potassium ions than conventional Prussian blue or its analogues because the support to which the prepared Prussian blue or analogues thereof is bonded is additionally reacted with sodium ions or potassium ions. ..

Although not bound by theory, in conventional conventional PB or PBA, Na ⁺ and/or K ⁺ ions are included in interstitial sites to cause an ion exchange reaction with a target substance, for example, NH ₄ ⁺ ions, to adsorb the target substance. It is known. However, since K ⁺ ions do not exist in vacancies in the crystal structure of PB or PBA, ion exchange reactions with NH ₄ ⁺ ions do not occur.

In contrast, the PB or PBA of the present invention increases the adsorption capacity of the target substance by increasing the interstitial site where Na ⁺ and/or K ⁺ ions exist through additional reaction with Na ⁺ and/or K ⁺ ions after PB or PBA synthesis. It is judged to be

In the above step, a step of removing unreacted compounds and the like by washing the support to which Prussian blue or its analogs additionally containing Na ⁺ and/or K ⁺ ions are bound with sufficient water after the reaction may be further included. The washed final composite may be further subjected to a drying step to remove moisture or the like. The drying step is not particularly limited, but may be performed at a temperature of about 30° C. or higher, for example, 30° C. to 70° C. for 10 hours to 36 hours under vacuum conditions.

In the method of the present invention, before step c), d) reacting the support to which Prussian blue (PB) or its analogue (PBA) is bonded with a metal cation precursor may be further included. Through the reaction in step d), the concentration of Prussian blue (PB) or its analogue (PBA) formed on the support can be further increased.

In step d), the metal cation is not particularly limited, but may be one selected from the group consisting of iron, cobalt, nickel, copper, and zinc.

In addition, metal cation precursors include oxides, chlorides, bromides, fluorides, and iodides of metal cations; acetide; nitric oxide; sulfur oxides; perchlorate; carbonylates; thiolate; fatty acid salts of saturated or unsaturated carbon chains; and phosphonates; One or more selected from may be used, but is not limited thereto, and for example, chloride, nitride or sulfur oxide may be used.

Reaction conditions in step d) of reacting the metal cation precursor with the support to which Prussian blue (PB) or its analogue (PBA) is bound are not particularly limited. The reaction of the metal cation precursor and the support may proceed in an aqueous solvent, for example water, for 10 hours to 36 hours. The reaction temperature and pressure are not particularly limited, and may be carried out, for example, at room temperature and pressure.

In step d), a step of removing unreacted precursors by washing with sufficient water after the metal cations are adsorbed on the support may be further included.

The present invention also relates to a composite prepared by the above-described manufacturing method.

The complex is

a support having a functional group capable of bonding with a metal cation;

It binds to the support through the functional group and includes PB or PBA represented by the following general formula 1,

The PB or PBA has a higher content of element A selected from sodium or potassium than conventional PB or PBA.

[Formula 1]

A _x M _a [M _b (CN) ₆ ] _y ㆍ _z H2O

in the above formula

A represents one or more cations selected from the group consisting of hydrogen, lithium, ammonium, sodium, potassium, rubidium, and cesium, preferably sodium or potassium, more preferably potassium,

M _a is one or more metal cations selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, europium, gadolinium, lutetium, barium, strontium and calcium; Represents, preferably selected from the group consisting of iron, cobalt, nickel, copper and zinc,

M _b represents one or more metal cations selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum and copper, preferably selected from iron or cobalt;

x represents a value from 0 to 3, y from 0.1 to 1.5, and z from 0 to 6.

Here, that the content of element A selected from sodium or potassium is higher than that of conventional PB or PBA may mean that the number of interstitial sites where Na ⁺ and/or K ⁺ ions exist is greater than that of conventional PB or PBA.

The present invention also relates to adsorbents of nitrogen-containing substances, specifically gaseous ammonia or liquid ammonium ions, comprising the complex. The nitrogen-containing material may include nitrogen-containing ammonia, ammonium ion, or an amine-based compound such as trimethylamine, but is not limited thereto.

The shape of the adsorbent is not particularly limited, but has a spherical shape and can be efficiently packed in a device such as a column. In this way, a system that simultaneously performs adsorption and desorption can be configured using a plurality of columns filled with the adsorbent of the present invention.

The present invention is also the adsorbent; and contacting ammonia or ammonium ions to adsorb the ammonia or ammonium ions on an adsorbent.

The capture method may include a step of desorbing the adsorbed ammonia or ammonium ion by contacting an alkali metal with an adsorbent having ammonia or ammonium ion adsorbed by the above step.

Conditions for the adsorption step and the desorption step are not particularly limited, and may be performed at room temperature and pressure. As the alkali metal used in the desorption step, sodium or potassium may be used. In one embodiment, sodium or potassium may be provided in ionic form in an aqueous sodium or potassium precursor solution. Sodium precursor or potassium precursor that can be used is sodium acetate, sodium bicarbonate, sodium boron hydride, sodium bromate, sodium bromide, sodium carbonate, sodium chlorate, sodium chloride, sodium citrate, sodium cyanide, sodium sulfate, sodium ethoxide, sodium fluoride, Sodium formate, sodium hydroxide, sodium iodide, sodium nitrate, sodium nitrite, sodium sulfate, potassium acetate, potassium bicarbonate, potassium boron hydride, potassium bromate, potassium bromide, potassium carbonate, potassium chlorate, potassium chloride, potassium citrate, potassium cyanide, potassium At least one selected from sulfate, potassium ethoxide, potassium fluoride, potassium formate, potassium hydroxide, potassium iodide, potassium nitrate, potassium nitrite, and potassium sulfate may be used, but is not limited thereto. The sodium precursor or potassium precursor may be, for example, one or more selected from sodium chloride, sodium cyanide, sodium sulfate, sodium hydroxide, sodium nitrate, sodium sulfate, potassium chloride, potassium cyanide, potassium sulfate, potassium hydroxide, potassium nitrate, or potassium sulfate. .

The composite according to the present invention can be used in the field of water treatment and gas phase, can be manufactured by a simple manufacturing process, has excellent selective adsorption capacity for ammonia or ammonium ions, and can regenerate the adsorbent by a simple process.

1 is a photograph showing the color change of particles for each manufacturing process of a composite according to an embodiment.
2 is a graph showing isothermal adsorption characteristics of composites according to Examples.
3 is a graph comparing adsorption performance of composites according to Examples and Comparative Examples.
Figure 4 is a graph showing the adsorption performance of the complex according to the pH according to the embodiment.
5 is a graph showing the selective adsorption capacity for competing ions of composites according to Examples.

Hereinafter, the present invention will be described in more detail through examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited by the examples presented below.

Example 1

After washing 100 mg of weak acidic cation exchange resin (model name: WCA, manufacturer: Samyang Corporation) with distilled water, react with 1000 mL of 500 mM CuCl ₂ 2H ₂ O for 24 hours, and Cu ²⁺ ions are adsorbed on the surface of weak acidic cation exchange resin. made it so After washing WCA-Cu ²⁺ with distilled water three or more times, WCA-KCuHCF (HCF: Hexa Cyano Ferrate) was synthesized by reacting with 1000 mL of 500 mM K ₄ Fe (CN) ₆ 3H ₂ O for 1 hour. The WCA-KCuHCF was washed three or more times with distilled water, the WCA-KCuHCF was impregnated with a 1 M KCl solution, reacted for 1 hour, washed three or more times with distilled water, and vacuum dried at 50 ° C. for one day to prepare a composite. As shown in FIG. 1, the color of WCA was ivory (FIG. 1a), but WCA-Cu ²⁺ combined with Cu ²⁺ cation was blue (FIG. 1b), and WCA-KCuHCF combined with HCF (hexacyanoferrate) was colored It was confirmed that the color changed to black (Fig. 1c).

Comparative Example 1

A composite was prepared in the same manner as in Example 1, except that WCA-KCuHCF was not reacted with 1 M KCl solution.

Experimental Example 1 - Isothermal Adsorption Characteristics

Isothermal adsorption experiments were performed at room temperature using a falcon tube (50 mL) made of polypropylene. After preparing a stock solution of 1,000 mg/L using an ammonium chloride (NH ₄ Cl, sigma aldrich) reagent, test samples were prepared at a concentration ranging from 1 to 1,000 mg/L, and the experiment was conducted. Then, the WCA-KCuHCF beads according to the examples were injected into each reaction solution at a concentration of 0.02 g/20 mL, and after stirring for 24 hours, the concentration change of NH ₄ ⁺ -N was observed.

Concentration change results are shown in FIG. 2 . In addition, as a result of substituting the results into the Langmuir and Freundlich isothermal adsorption equations, it was found that they conformed well to the isothermal adsorption equations, which are shown in Table 1.

Example Langmuir isotherm Freundlich isotherm qmax
(mg/g) b
(L/mg) ^R2 K _f
(mg ^1-1/n L ^1/n /g) 1/n ^R2 WCA-KCuHCF 38.3630 0.0427 0.99220 16.1909 0.1291 0.7963

Experimental Example 2 - Effect of KCl reaction

In order to compare the adsorption performance of WCA-KCuHCF before and after KCl reaction, a 10 mg/L solution of NH ₄ ⁺ -N was prepared, and then the WCA-KCuHCF impregnated with KCl at a concentration of 0.02 g/20 mL and the adsorbent without impregnation were tested, respectively. Ammonia adsorption performance was compared by injection, and the results are shown in FIG. 3. As shown in Figure 3, the WCA-KCuHCF beads of Comparative Example not further reacted with KCl (w / o KCl) showed an adsorption capacity of 8.04 mg / g, whereas the WCA-KCuHCF beads of Example further reacted with KCl (w / o KCl) showed an adsorption capacity of 12.80 mg / g, confirming that the adsorption capacity increased by 59.2%.

Experimental Example 3 - Effect of pH

In order to evaluate the pH effect on ammonium adsorption of WCA-KCuHCF beads according to the embodiment, the concentration of NH ₄ ⁺ -N solution was prepared at 20 mg / L, respectively, and then the pH range was 2-9 using NaOH and HNO ₃ Adjusted to analyze the effect on pH, the results are shown in Figure 4.

As shown in FIG. 4, it was observed that the adsorption performance slightly decreased at pH 4, but it was not a serious level, and relatively stable NH ₄ ⁺ -N adsorption characteristics were exhibited between pH 5 and 9.

Experimental Example 4 - Selective adsorption capacity for competing ions

In order to evaluate the selective adsorption capacity of ammonium ions of the adsorbent for competing ions, Na, K, Mg, and Ca were prepared at 1,000 mg/L and the NH ₄ ⁺ -N concentration was 100 mg/L, and WCA- The selectivity of KCuHCF beads for NH ₄ ⁺ -N ions was analyzed, and this is shown in FIG. 5 . It was confirmed that the adsorption capacity for NH ₄ ⁺ -N ions was maintained to some extent even in the presence of competing ions, and NH ₄ ⁺ - in competition with K ⁺ ions compared to Na ⁺ , Mg ²⁺ , and Ca ²⁺ ions. The adsorption rate of N was rather low.

The present invention described above is not limited to the above-described embodiments, since various substitutions and changes can be made to those skilled in the art within the scope of the technical idea of the present invention. .

Claims (14)

a) preparing a metal cation-bound support by reacting a metal cation precursor with a support having a functional group capable of bonding with the metal cation;
b) reacting a metal cyanide compound with a metal cation bound to the support to form Prussian blue (PB) or an analog thereof (PBA) on the support; and
c) A method for producing a composite comprising Prussian blue (PB) or an analog thereof (PBA) comprising the step of reacting an alkali metal with Prussian blue (PB) or an analog thereof (PBA) formed on the support. According to claim 1,
A method for producing a composite in which the metal cation is at least one selected from the group consisting of iron, cobalt, nickel, copper and zinc. According to claim 1,
Metal cation precursors include oxides, chlorides, bromides, fluorides, iodides of metal cations; acetide; nitric oxide; sulfur oxides; perchlorate; carbonylates; thiolate; fatty acid salts of saturated or unsaturated carbon chains; and phosphonates; Method for producing a composite of at least one selected from among. According to claim 1,
A method for producing a complex in which a functional group capable of bonding with a metal cation is -COO ^- , -SO ₃ ^- , or a ligand. According to claim 1,
A method for producing a complex in which the support having a functional group capable of bonding with a metal cation is a cation exchange resin. According to claim 1,
The metal cyanide compound is Na ₄ [Fe(CN) ₆ ], Na ₃ [Co(CN) ₆ ], K ₄ [Fe(CN) ₆ ] or K ₃ [Co(CN) ₆ ] Method for producing a composite. According to claim 1,
Method for producing a complex in which the alkali metal is at least one selected from sodium or potassium. The method of claim 1, before step c),
d) A method for preparing a composite, further comprising reacting a support to which Prussian blue (PB) or an analogue thereof (PBA) is bound with a metal cation precursor. According to claim 8,
A method for producing a composite in which the metal cation is at least one selected from the group consisting of iron, cobalt, nickel, copper and zinc. According to claim 8,
Metal cation precursors include oxides, chlorides, bromides, fluorides, iodides of metal cations; acetide; nitric oxide; sulfur oxides; perchlorate; carbonylates; thiolate; fatty acid salts of saturated or unsaturated carbon chains; and phosphonates; Method for producing a composite of at least one selected from among. A composite prepared by the method of any one of claims 1 to 10. An adsorbent for ammonia or ammonium ions comprising the complex according to claim 11. The adsorbent according to claim 12; and contacting ammonia or ammonium ions to adsorb the ammonia or ammonium ions on an adsorbent. The method of claim 13, further comprising the step of desorbing the adsorbed ammonia or ammonium ions by contacting an alkali metal with an adsorbent on which ammonia or ammonium ions are adsorbed.

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