KR100560831B1 - Nanostructural ferric catalyst for wastewater fenton oxidation treatment and the Producing method hereof - Google Patents

Abstract

The present invention relates to a method for producing an iron catalyst that can improve the disadvantages of the fenton oxidation method, which is one of wastewater treatment methods. The generation of iron slurry, which is pointed out as a disadvantage of the fenton oxidation treatment, the need for artificial pH condition setting, the residual hydrogen peroxide solution after the reaction, etc. can be solved by the present invention.

In the present invention, since the iron catalyst insoluble in water is used, the problem of iron slurry does not occur, so that it can be reused, and the recovery is facilitated by coating the catalyst on the fixed phase. Catalytic coating methods include electrochemical methods and chemical vapor deposition (CVD) coating methods, but the efficiency of the catalyst prepared by the conventional coating method is known to be considerably lower than that of the slurry using the catalyst. . However, according to the present invention, the efficiency is increased by increasing the surface area of the catalyst.

The present invention uses a reducing agent such as hydrazine or borohydride with iron ions such as acetate iron, iron sulfate, ammonium iron, iron hydrochloride, iron carbonate, iron bromide, iron fluoride, iron iodide, iron oxalate, and iron phosphate as starting materials. The present invention provides a method for producing an iron catalyst nanostructure for fenton oxidation treatment, and a method of using the product and waste water treatment by making reduced iron and then molding the mold using a membrane and firing it at 100 to 1000 ° C.

Iron catalyst, Fenton oxidation method, iron slurry, iron acetate, iron sulfate, iron ammonium, iron hydrochloride, iron carbonate, iron bromide, iron fluoride, iron iodide, iron nitrate, iron oxalate, iron phosphate, hydrazine, borohydride, poly Carbonate membrane, stationary phase, inorganic binder.

Description

Nanostructured ferric catalyst for wastewater fenton oxidation treatment and the Producing method hereof}

1 is a diagram of a comparison of the phenol degradability of the catalyst (A is an iron catalyst nanostructure prepared by the present invention, B is a thin film (cat) thin film (thin film) iron catalyst prepared by the conventional coating method, C is Only hydrogen peroxide solution added without iron catalyst).

Figure 2 is a view of the electron microscope (40000X) photograph of the fibrous type iron catalyst nanostructure produced by the present invention.

Figure 3 is a view of the electron microscope (20000X) photograph of the fibrous type iron catalyst nanostructures produced by the present invention.

Figure 4 is a view of the electron microscope (100000X) photograph of the fibrous type iron catalyst nanostructure produced by the present invention.

The wastewater treatment methods known to date include biological and chemical methods called activated sludge methods, which take a long time to decompose organic compounds and dilute wastewater to concentrations suitable for algae and bacteria growth. A large space is required to set up a treatment facility, and wastewater containing aromatic organic matter, which is a hardly decomposable substance, has a disadvantage in that the activated sludge is discharged without being decomposed due to shock or poor treatment.

 Currently, the most commonly used chemical treatment methods are iron oxidation, Fenton oxidation, ozone oxidation, and the like. The iron oxidation method uses simple oxidation and agglomeration using ferrous iron and ferric iron, which is inexpensive, easy to process, excellent in coagulation, and low in processing efficiency. The ozone oxidation method is useful for treating drinking water, but due to the high cost of treatment, the concern of secondary pollution to ozone, adsorption treatment of gas generated after ozone treatment with activated carbon, and the complexity of the ozone generator, It is not suitable for the treatment efficiency of contained wastewater. Fenton oxidation method uses hydrogen peroxide with high oxidizing power under acidic conditions using ferrous iron or ferric iron, which shows relatively high treatment efficiency, but it is almost impossible to treat wastewater containing hardly decomposable organic matter.

Fenton oxidation method oxidizes organic matter by the following mechanism.

^{_{Fe 2+ + H 2 O 2 →}} Fe 3+ + HO - + OH ·

Fe ³⁺ + H ₂ O ₂ → Fe ²⁺ + HO ₂ + H ⁺

Fe ³⁺ + HO _2- > Fe ²⁺ + O ₂ + H ⁺

OH + H ₂ O ₂ → HO ₂ + H ₂ O

In the conventional fenton oxidation method, pH is important. Since the reaction proceeds only when the pH is maintained between 3 and 4, the problem of corrosion of the reaction tank occurs, and an alkaline agent such as sodium hydroxide should be used since the pH must be adjusted to neutral again after the reaction. The fenton oxidation method generates OH radicals by oxidizing Fe ^{2+ to} Fe ³⁺ by hydrogen peroxide solution, and the oxidation reaction proceeds by the OH radicals. In this reaction, Fe ³⁺ must be reduced back to Fe ²⁺ by hydrogen peroxide to continue the phentone oxidation reaction. Since the rate of iron oxidation is faster than the rate of reduction, trivalent iron accumulates, thereby reducing the reaction efficiency. do. Finally, the reaction no longer proceeds. This ineffective catalyst is used to increase the pH using a caustic soda to make insoluble iron hydroxide and then remove it. In this process, a large amount of iron sludge to be generated is generated.

In order to recycle the catalyst, the catalyst must be easily recovered. However, the catalyst is often recovered by using a filter by a conventional method. However, there are many problems in the recovery method using such a filter. Since the efficiency of the filter tends to decrease with use time, the filter needs to be replaced frequently. This problem of catalyst recovery can be solved by coating the catalyst on a fixed bed. Such catalytic coating methods include electrochemical methods and coating methods using chemical vapor deposition (CVD).

The electrochemical method has the advantage that the coating is uniform and adheres very firmly upon coating, but there is a disadvantage that the coating is only possible for the conductive conductor, and the specific surface area is also small. In the case of coating by chemical vapor deposition (CVD), there is an advantage that the coating is firmly attached, but like the electrochemical method, the stationary phase to which the coating can be applied is limited and the coating cost is high. In addition, it is generally known that the efficiency of a catalyst prepared by coating is considerably lower than that of a slurry. The decrease in catalyst efficiency generated when the catalyst is fixed can be overcome by increasing the specific surface area of the coated catalyst. When coating the catalyst on the fixed bed, the surface area is increased to increase the efficiency of the catalyst in proportion to the surface area. Since the nanostructure using the template synthesis method has a specific surface area of about 300 times or more as compared to the general coating method, the efficiency of the catalyst is also proportional to this. It grows bigger.

In the present invention, to provide a method for producing an iron catalyst with the maximum activity of the catalyst using the template synthesis method.

The present invention is to solve the disadvantages of the conventional Fenton oxidation process. There are three major disadvantages of the Fenton oxidation treatment. First, iron slurries are generated from the iron used as a catalyst after the Fenton treatment. Second, because the Fenton treatment proceeds only under acidic conditions, it is necessary to artificially adjust the pH. Third, the Fenton treatment puts an excess of hydrogen peroxide solution, so that there is hydrogen peroxide solution that does not react after treatment.

 Iron slurries are generated because iron catalysts are ionic and are soluble in water. Therefore, alkaline iron is added to remove iron ions by making them insoluble iron hydroxide. The catalyst which is insoluble in water, which improves these disadvantages, is insoluble in the recovery of the catalyst and is insoluble in water, resulting in a decrease in the catalyst efficiency. In order to overcome this disadvantage, the problem of recovery can be solved by attaching the catalyst to the stationary phase, but the catalyst prepared in this way has a lower specific surface area, which results in lower efficiency than the slurry type.

The present invention aims to fundamentally eliminate the generation of iron slurries and fundamentally improve the catalyst recovery problem and the efficiency reduction by producing nanostructures using the iron-insoluble iron catalyst using a template synthesis method.

In the present invention, iron ions such as iron acetate, iron sulfate, iron ammonium, iron hydrochloride, iron carbonate, iron bromide, iron fluoride, iron iodide, iron nitrate, iron oxalate, and iron phosphate are used as starting materials. Iron acetate, iron sulfate, iron ammonium, iron hydrochloride, iron carbonate, iron bromide, iron fluoride, iron iodide, iron nitrate, iron oxalate, iron phosphate, etc. are dissolved in water, and then reducing agents such as hydrazine and borohydride are added. After the iron ions were appropriately reduced, the reduced iron was immersed in a polycarbonate membrane to allow sufficient reduced iron to enter the polar carbonate membrane. This was fixed to a stationary phase using an inorganic binder such as water glass, and then fired at an appropriate temperature (100 to 1000 ° C.) to prepare an iron catalyst nanostructure.

The iron catalyst thus prepared has an oxidized water in which 0, di, and trivalents are mixed according to the above conditions, and a fibrous or tubular nanostructure is produced. The iron catalyst mixed with 0, di, and trivalents reacts well with hydrogen peroxide to produce an oxidation reaction, and thus can be used as a catalyst for Fenton reaction with good efficiency. Highly efficient catalysts can be produced.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Acetate iron was dissolved in water, and then hydrazine was added to the solution to reduce the iron and soak it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 2

Iron sulfate was dissolved in water, and then hydrazine was added to the solution to reduce iron, which was then immersed in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

EXAMPLE 3]

Iron ammonium was dissolved in water and then hydrazine was added to the solution to reduce iron and soak it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

EXAMPLE 4]

Iron hydrochloride was dissolved in water, and then hydrazine was added to the solution to reduce iron and immerse it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 5

Iron carbonate was dissolved in water, and then hydrazine was added to the solution to reduce iron, which was then immersed in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 6

Iron bromide was dissolved in water, and then hydrazine was added to the solution to reduce the iron and soak it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 7

Fluorine iron was dissolved in water, and then hydrazine was added to the solution to reduce iron and soak in polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to the stationary phase using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 8

Iron iodide was dissolved in water, and then hydrazine was added to the solution to reduce iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 9

Iron nitrate was dissolved in water and then hydrazine was added to the solution to reduce iron and soak it in a polycarbonate membrane to allow the reduced iron to soak into the pupil of the membrane sufficiently. The reduced iron-containing membrane was attached to a stationary phase using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 10

Iron oxalate was dissolved in water, and then hydrazine was added to the solution to reduce iron and immerse it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 11

Iron phosphate was dissolved in water, and then hydrazine was added to the solution to reduce iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 12

Acetate iron was dissolved in water, and then borohydride was added to the solution to reduce iron and soak it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 13

Iron sulfate was dissolved in water, and then borohydride was added to the solution to reduce iron and immerse it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 14

Iron ammonium was dissolved in water and then borohydride was added to the solution to reduce the iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently infiltrate the cavity of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 15

Iron hydrochloride was dissolved in water, and then borohydride was added to the solution to reduce iron and soak it in a polycarbonate membrane so that the reduced iron was sufficiently penetrated into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 16

Iron carbonate was dissolved in water, and then borohydride was added to the solution to reduce iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 17

Iron bromide was dissolved in water, and then borohydride was added to the solution to reduce iron, which was then immersed in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 18

After fluorine iron was dissolved in water, borohydride was added to the solution to reduce iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 19

Iron iodide was dissolved in water and then borohydride was added to the solution to reduce the iron and soak it in a polycarbonate membrane to allow the reduced iron to sufficiently infiltrate the cavity of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 20

Iron nitrate was dissolved in water and then borohydride was added to the solution to reduce iron and immerse it in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 21

Iron oxalate was dissolved in water, and then borohydride was added to the solution to reduce iron, which was then immersed in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Example 22

After iron phosphate was dissolved in water, borohydride was added to the solution to reduce iron, which was then immersed in a polycarbonate membrane to allow the reduced iron to sufficiently permeate into the pupil of the membrane. The reduced iron-containing membrane was attached to a stationary phase by using an inorganic binder such as water glass, and then sintered at a temperature between 100 and 1000 ° C. for 2 to 8 hours using an electric furnace to prepare an iron catalyst nanostructure.

Hereinafter, the iron catalyst prepared according to the present invention is treated in wastewater containing phenol, which is a hardly decomposable organic substance, and the resolution and residual amount of hydrogen peroxide water are checked, and the catalyst produced by the existing method and the catalyst are not added. If not, the comparison was made.

[Processing Example 1]

After adding acid to 100 mL of wastewater containing 200 ppm of phenol, which is a hardly decomposable organic substance, the pH was adjusted to 3. Then, the catalyst prepared according to the present invention was added, and 0.1 mL of 35% hydrogen peroxide solution was added and reacted. After reaction at room temperature for 10 minutes, phenol was decomposed more than 99%. In addition, as a result of confirming the residual amount of hydrogen peroxide after the reaction, it was confirmed that the hydrogen peroxide water was decomposed more than 99% after 40 minutes.

Comparative Processing Example 1

After adding acid to 100 mL of wastewater containing 200 ppm of phenol, which is a hardly decomposable organic substance, the pH was adjusted to 3, and then a catalyst prepared by the conventional coating method was added, and 0.1 mL of 35% hydrogen peroxide solution was added and reacted. . After reaction at room temperature for 10 minutes, phenol decomposed about 25%. In addition, as a result of confirming the residual amount of hydrogen peroxide after the reaction, it was confirmed that the hydrogen peroxide water was decomposed at least 70% after 40 minutes.

Comparative Processing Example 2

After adding acid to 100 mL of wastewater containing 200 ppm of phenol, which is a hardly decomposable organic substance, the pH was adjusted to 3, and then reacted with 0.1 mL of 35% hydrogen peroxide solution without adding a catalyst. After 10 minutes of reaction at room temperature, phenol was decomposed about 10%. In addition, as a result of confirming the residual amount of hydrogen peroxide after the reaction, it was confirmed that after 40 minutes, the hydrogen peroxide water was decomposed more than 90%.

In the conventional Fenton oxidation method, the pH is maintained between 3 and 4 so that the reaction proceeds. Therefore, the problem of corrosion of the reaction tank occurs, and the pH must be adjusted to neutral after the reaction, and an alkali agent such as sodium hydroxide should be used. In the method of the present invention, the reaction occurs well in all of neutral, acidic and alkaline. Since most wastewaters are about acidic, pH = 6, there is no need to artificially manipulate the pH, so there is no need to artificially manipulate the pH to neutralize the tank after corrosion or reaction.

The fenton oxidation method generates OH radicals by oxidizing Fe ^{2+ to} Fe ³⁺ by hydrogen peroxide solution, and the oxidation reaction proceeds by the OH radicals. In this reaction, Fe ³⁺ must be reduced back to Fe ²⁺ by hydrogen peroxide to continue the phentone oxidation reaction. Since the rate of iron oxidation is faster than the rate of reduction, trivalent iron accumulates, thereby reducing the reaction efficiency. In the end, the reaction will not proceed anymore, so the insoluble catalyst is increased by using a caustic soda such as caustic soda to make insoluble iron hydroxide and then remove it. In this process, a large amount of iron sludge to be generated is generated. In the present invention, since the iron catalyst insoluble in water is used, the problem of iron slurry does not occur, and the catalyst can be reused.

In order to recycle the catalyst, it is necessary to easily recover the catalyst. The recovery of the catalyst is often performed by using a filter using a conventional method. However, in the recovery method using such a filter, the efficiency of the filter decreases with use time. As a result, the filter needs to be replaced frequently. The problem of catalyst recovery can be solved by coating the catalyst on the fixed phase. Among the catalyst coating methods, the electrochemical method has the advantage of uniform coating and very hard adhesion during coating. The specific surface area is also small. In the case of coating by chemical vapor deposition (CVD), there is an advantage that the coating is firmly attached, but like the electrochemical method, the stationary phase to which the coating can be applied is limited and the coating cost is high. In addition, it is generally known that the efficiency of a catalyst prepared by coating is considerably lower than that of a slurry. According to the present invention, a catalyst having a specific surface area of about 600 times larger than that of the catalyst prepared by the conventional method may be prepared using the template synthesis method, thereby maximizing the efficiency of the catalyst.

Therefore, according to the present invention, a highly active and recyclable iron catalyst can be prepared, and the catalyst according to the present invention is useful for poorly soluble wastewater treatment and does not need to be artificially manipulated in pH because it is not bound to acid conditions during treatment. In addition, iron slurries are not generated and residual hydrogen peroxide water is scarcely applied to the treatment of drinking water, and wastewater treatment costs can be reduced.

Claims (4)

delete Reducing iron using reducing agent using ionic iron selected from any one of acetate iron, iron sulfate, iron ammonium, iron hydrochloride, iron carbonate, iron bromide, iron fluoride, iron iodide, iron oxalate and iron phosphate as starting materials First step; A second step of synthesizing the reduced iron by using a membrane; It characterized in that it comprises a third step of firing the synthesized mold between 100 to 1000 ℃, Method for preparing an iron catalyst nanostructure for fenton oxidation treatment. The method of claim 2, The reducing agent is selected from the group consisting of hydrazine or borohydride, Method for preparing an iron catalyst nanostructure for fenton oxidation treatment. Iron catalyst nanostructure for fenton oxidation treatment prepared by the method of claim 2 or 3.

Images