KR102334142B1 - A method for preparing biomass-based absorbent for removing radionuclides or heavy-metal, a absorbent thereby, and a use of the same - Google Patents

Abstract

The present invention relates to a preparation method of a biomass-based adsorbent for removing a radionuclide or a heavy metal, a biomass-based adsorbent prepared thereby, and a method for removing a radionuclide or a heavy metal from a target object using the adsorbent. The preparation method of a biomass-based adsorbent for removing a radionuclide or a heavy metal comprises the steps of: a) washing biomass with water and drying the same so as to carbonize the biomass; and b) reforming the carbide obtained in step (a) through an alkali oxidation method.

Description

A method for manufacturing a biomass-based adsorbent for the removal of radionuclides or heavy metals, an adsorbent prepared by the method, and the use of the adsorbent OF THE SAME}

The present invention relates to a method for manufacturing a biomass-based adsorbent for removing radionuclides or heavy metals, an adsorbent prepared by the method, and use of the adsorbent.

Nuclear power plants regularly use a significant amount of ion exchange resin to purify reactor system water and secondary system water, and research institutes and university laboratories also use ion exchange resin to purify radioactive contaminants.

Among the waste resins generated in the purification process, the waste resin with a relatively low radioactivity level is the CPP (Condensate Polishing Plant) waste resin generated during the condensate purification process of the turbine condensate system and the BD (Blowdown) generated during the purification of the steam generator discharge water system. There is a waste resin, and as a waste resin with a slightly higher radioactivity level, there is a waste resin generated during the liquid waste purification process in the Liquid Radwaste System (LRS).

In general, about 5,000 to 7,000 liters of waste resin is generated per unit per year, and the generated waste resin is placed in sacks or carbon steel drums depending on the level of radioactivity and temporarily stored in the power plant for permanent disposal.

In the case of detection of even trace amounts of radioactivity in waste resins generated from nuclear power plants, the entire amount is stabilized, put in drums, and sent to a radioactive waste disposal site. It is impossible to classify such radioactive waste as general waste unless the radioactivity is lowered to the level of radioactivity that can be disposed of by itself. In particular, if there is a leak in the tube of the steam generator, the waste resin generated during the purification of the extraction water system on the secondary side of the steam generator is radiocarbon (14C) with a long half-life, radioactive cesium (137Cs), and radioactive cobalt (60Co). It is contaminated with radionuclides, and since the radioactivity does not disappear completely even after long-term storage, the contaminated waste resin cannot be classified as general waste and treated.

Ion exchange resins are made of high molecular weight polymers with excellent mechanical strength or chemical resistance, and since functional groups on the surface are replaced with radionuclides and remain in ion exchange form, it is very difficult to separate and extract radionuclides attached to the resin. Therefore, it is very important to develop a technology to separate and extract radionuclides to the extent that they can be disposed of on their own from such polluted waste resins in terms of reduction of radioactive waste and reduction of disposal costs.

In addition, wastewater containing many pollutants is generated in various environments around us, and if such wastewater is discharged into the water system as it is, rivers and seas are polluted, exposing people to the polluted living environment, and destroying the ecosystem. Therefore, the wastewater that has undergone the purification process must be discharged. In order to purify wastewater containing such pollutants and organic matter, the field of water treatment has been continuously developed, but the concept of convenience, economy, and environment-friendly water treatment process and its application are insufficient.

Therefore, there is a need for a technology capable of finding microorganisms that biodegrade organic matter and responding to simple water treatment facilities.

A well-known technology in the field of existing wastewater purification technology is the "activated sludge method" and its improvement method. This technology became known all over the world when the improved method developed in England came out in 1913, and made a great contribution to organic wastewater treatment including domestic wastewater.

However, this technology requires a lot of initial investment, management and maintenance costs, and requires specialized knowledge due to difficult operation technology. In particular, it has a problem in its treatment because a large amount of sludge is generated.

As a prior art for purifying wastewater in the prior art, in Korean Patent No. 10-1367642, a suspended matter remover that receives wastewater supplied from a wastewater generator and removes suspended matter contained in the wastewater, and the suspended matter remover is discharged A reaction tank for purifying wastewater is provided. The reaction tank is filled with wood chips of 2 to 10 mm with a porous surface area of 10 m 2 /g or more by heating while irradiating 5 to 20 μm of far-infrared rays. An interposed temporary storage tank, a conveyor having one end positioned within the temporary storage tank and the other end extending outside the temporary storage tank to be installed at a higher position than the one end position, and rotatably fastened to both ends of the conveyor There is disclosed a wastewater purification device including a belt made of a sieve, and configured such that the wastewater flowing into the temporary storage tank from the wastewater generator flows through the belt region.

The present invention solves the above problems, and an object of the present invention is to provide a method for manufacturing a biomass-based adsorbent for removing radionuclides or heavy metals as devised by the above necessity.

Another object of the present invention is to provide a method for the removal of radionuclides and/or waterborne contaminants.

In order to achieve the above object, the present invention comprises the steps of: a) washing biomass with water, drying and carbonizing; and

It provides a method for preparing a biomass-based adsorbent for removing radionuclides or heavy metals, comprising the step of b) reforming the carbide through an alkali oxidation method.

In one embodiment of the present invention,

The biomass is preferably walnut shell, rice bran, sawdust, coffee gourd, rice bran, red pepper stem, organic sludge, fruit peel, forestry by-product, or forest by-product, but is not limited thereto.

In another embodiment of the present invention,

In the carbonization step of a), the biomass is put into an electric furnace, heated to 300-900°C at 1-20°C/min under 0.1-2 L nitrogen gas/min, and then maintained at 300-900°C for 0.5-6 hours and allowed to cool It is preferable to include the step of, but is not limited thereto

In another embodiment of the present invention,

In step b), the carbide obtained in step a) and the alkali oxidation solution (pH 8 or higher, a mixture of oxidizing agent and hydroxide) are mixed in a ratio of 1:1 to 1:500 (w/v) for more than 0 and within 24 hours. It is preferable to include the step of processing, but is not limited thereto.

In another embodiment of the present invention,

The oxidizing agent used in the above is preferably hydrogen peroxide, ozone, or a mixture of hydrogen peroxide and ozone, but is not limited thereto.

In another embodiment of the present invention,

The hydroxide used in the above is preferably NaOH, KOH, Ca(OH) ₂ , or Mg(OH) ₂ , but is not limited thereto.

In addition, the present invention provides a biomass-based adsorbent prepared by the method of the present invention.

The present invention also provides a kit for removing radionuclides comprising the biomass-based adsorbent of the present invention.

The present invention also provides a kit for removing heavy metals comprising the biomass-based adsorbent of the present invention.

In addition, the present invention provides a method for removing radionuclides or heavy metals from the target by treating the biomass-based adsorbent of the present invention to a target containing a radionuclide or a heavy metal.

In one embodiment of the present invention,

The adsorbent dosage is preferably 0.001 ~ 50 g / L, but is not limited thereto.

In another embodiment of the present invention,

The concentration of the target to be removed is preferably less than 10 g/L, but is not limited thereto.

Hereinafter, the present invention will be described.

The present invention provides a method for producing biochar through a very simple pyrolysis process based on various biomass and reforming it through an alkali oxidizing agent for the removal of radionuclides.

The biomass-based adsorbent manufacturing method of the present invention is

Although detailed in Figure 1, in brief summary,

a) washing various biomass (walnut shells, rice bran, sawdust, coffee gourd, rice bran, red pepper cod, organic sludge, fruit shells, forestry by-products, forest by-products, etc.), drying, and carbonizing; b) reforming the carbide through alkali oxidation as a major step.

The carbonization step is to put the dried biomass in an electric furnace and raise the temperature to 300-900°C at 1-20°C/min under 0.1-2 L nitrogen gas/min, then maintain at 300-900°C for 0.5-6 hours and allow to cool includes steps.

In step b), the carbide obtained in step a) and the alkali oxidation solution (pH 8 or higher, a mixture of oxidizing agent and hydroxide) are mixed in a ratio of 1:1 to 1:500 (w/v) for more than 0 and within 24 hours. post-processing.

The oxidizing agent used in step b) is preferably hydrogen peroxide, ozone, hydrogen peroxide and ozone, but is not limited thereto,

The hydroxide used in step b) is preferably NaOH, KOH, Ca(OH) ₂ , or Mg(OH) ₂ , but is not limited thereto.

The concentration of the alkali solution used in step b) was used at a concentration of more than 0 and less than or equal to 5M.

In addition, the manufacturing method of the present invention may further include a process of selecting only those that have passed through the mesh sieve through an 80-625 mesh sieve by washing and drying the post-processed ones after step b).

A method for removing radionuclides and water-based pollutants using the biomass-based adsorbent prepared by the biomass-based adsorbent manufacturing method of the present invention is described in detail in FIG. 2 .

to summarize,

a) a biomass-based adsorbent input amount (0.001-50 g/L) prepared by the biomass-based adsorbent manufacturing method of the present invention;

b) the pH of the treatment solution (3 to 11);

c) the temperature of the treatment solution (5 ~ 45 ℃);

d) adsorption time (more than 0 144 hours);

e) concentration of material to be removed (< 10 g/L);

f) stirring RPM (50 to 300);

g) Target substances: organic substances (trace pollutants, dyes, natural organic substances, etc.), inorganic substances (heavy metals, etc.), and radionuclides (cesium, strontium, uranium, totium, iodine, etc.).

As can be seen from the present invention, the biochar manufacturing method for the removal of radionuclides and water-based contaminants of the present invention can produce a simple and easy biomass-based adsorbent by carbonizing a raw material and then reforming it very easily with an oxidizing agent. In addition, it includes a new alkali oxidation method that can effectively transform coffee bean bio-cha, which cannot be reformed by conventional oxidation methods.

In addition, activated carbon, which is an adsorbent applied to the existing water treatment process, can be applied in such fields as it is used for the removal of inorganic or organic substances in water, the removal of inorganic substances from the soil, composite materials for improving construction properties, and air pollution improvement. Since it can effectively remove nuclides, the marketability is judged to be very high.

1 is a diagram showing a biomass-based adsorbent manufacturing process;
Figure 2 is a figure showing a method of removing radionuclides and water-based pollutants through a biomass-based adsorbent;
3 is a diagram showing the results of a strontium removal experiment using the coffee leaf-based adsorbent of the present invention;
In the figure, S-Biochar: An adsorbent produced by thermal decomposition at 500°C for 2 hours by raising the temperature at 10°C per minute under the nitrogen condition of 0.25 L/min.
S-HP-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 15% hydrogen peroxide for 24 hours;
S-AO-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 1M sodium hydroxide and 0.125 mM ozone for 24 hours;
S-AHP-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 15% hydrogen peroxide and 1 M sodium hydroxide for 24 hours, and
S-AAO-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 7.5% hydrogen peroxide, 1 M sodium hydroxide and 0.125 mM ozone for 24 hours;
Figure 4 is a figure showing the results of heavy metal removal experiments through the coffee grounds-based adsorbent,
In the figure, S-Biochar: An adsorbent produced by thermal decomposition at 500°C for 2 hours by raising the temperature at 10°C per minute under the nitrogen condition of 0.25 L/min.
S-HP-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 15% hydrogen peroxide for 24 hours, and
S-AHP-Biochar: adsorbent produced by mixing 2 g of S-Biochar with 200 mL of 15% hydrogen peroxide and 1 M sodium hydroxide for 24 hours

Hereinafter, the present invention will be described in more detail through non-limiting examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not to be construed as being limited by the following examples.

Example 1: Preparation of biomass-based adsorbent

The method for preparing the biomass-based adsorbent of the present invention is described in detail in FIG. 1 .

The main process is

a) washing various biomass (walnut shells, rice bran, sawdust, coffee gourd, rice bran, red pepper cod, organic sludge, fruit shells, forestry by-products, forest by-products, etc.), drying, and carbonizing; b) reforming the carbide through alkali oxidation.

In the actual production example

For step a), the coffee foil was pyrolyzed at 500 °C for 2 hours by increasing the temperature at 10 °C per minute under nitrogen conditions of 0.25 L/min,

For step b), 2 g of the thermal decomposition product obtained in step a) was mixed with 200 mL of 15% hydrogen peroxide and 1M sodium hydroxide for 24 hours, or

2 g of the thermal decomposition product obtained in step a) was mixed with 200 mL of 1M sodium hydroxide and 0.125 mM ozone for 24 hours, or

2 g of the thermal decomposition product obtained in step a) was mixed with 200 mL of 7.5% hydrogen peroxide, 1 M sodium hydroxide and 0.125 mM ozone for 24 hours.

Example 2: Method of removing radionuclides and water-based pollutants using biomass-based adsorbent

A method of removing radionuclides and water-based pollutants through a biomass-based adsorbent is described in detail in FIG. 2 .

To elaborate on this,

0.001-50 g/L of the adsorbent prepared in Example 1 was added;

At this time, the pH of the treatment solution was 3 to 11;

c) the temperature of the treatment solution was 5 to 45 °C;

d) the adsorption time of the adsorbent to the target material was between 0 and 144 hours;

e) the concentration of the material to be removed (<10 g/L);

f) stirring RPM (50-300);

g) Target substances: organic substances (trace pollutants, dyes, natural organic substances, etc.),

inorganic substances (heavy metals, etc.),

They were radionuclides (cesium, strontium, uranium, totium, iodine, etc.).

In relation to Example 2, the results of the strontium removal experiment performed using the coffee bean-based adsorbent are shown in FIG. 3 .

The conditions of the experiment performed in FIG. 3 are as follows.

Adsorbent capacity = 0.3 g/L,

solution pH = 5,

solution temperature = 25 ° C,

agitation speed = 150 rpm;

Initial concentration of strontium ion = 5 mg/L,

contact time = 24 h

As can be seen in Figure 3,

For the removal of radioactive strontium ions,

When reforming using only 15% hydrogen peroxide (S-HP-Biochar), which is the existing oxidation method, there was a slight difference from the existing coffee bean biochar (S-Biochar),

AO (alkali ozonation), AHP (alkali hydroperoxide), and AAO (alklai advanced oxidation) showed excellent effects, indicating that the alkali oxidation reforming method was very effective.

4 shows the results of a heavy metal removal experiment using a coffee bean-based adsorbent in relation to Example 2 above.

The conditions of the experiment performed in FIG. 4 are as follows.

Adsorbent capacity = 0.3 g/L,

solution pH = 5,

solution temperature = 25 ° C,

agitation speed = 150 rpm;

Initial concentration of each heavy metal = 30 μM,

Contact time = 24 h.

As can be seen in Figure 4,

In the case of removal of heavy metal ions, when reforming using only 15% hydrogen peroxide (S-HP-Biochar), which is the existing oxidation method, there was a slight difference from the existing coffee bean biochar (S-Biochar), but 15% hydrogen peroxide and As the performance of the adsorbent (S-AHP-Biochar) post-treated with 1 M sodium hydroxide mixture was the most dominant, it was found that the alkali oxidation method was effective.

Claims (12)

a) washing the coffee grounds with water, drying and carbonizing; and
b) A method for preparing an adsorbent for strontium removal, comprising mixing 2 g of the a) carbide with 200 mL of 7.5% hydrogen peroxide, 1 M sodium hydroxide and 0.125 mM ozone for 24 hours. delete The method of claim 1,
Step a) is a method for producing an adsorbent for strontium removal, characterized in that the coffee grounds are heated at a rate of 10° C. per minute under nitrogen conditions of 0.25 L/min and thermally decomposed at 500° C. for 2 hours. delete delete delete An adsorbent for strontium removal prepared by the method of any one of claims 1 and 3. delete delete delete delete delete

Images