KR102521098B1 - Alginate liquid filter and waste water purification method using the same - Google Patents

Abstract

The present invention is a filter for separating heavy metals using alginic acid, wherein the filter includes a plurality of filter parts, the filter parts include alginate solutions of different concentrations, and the filter parts are separated through filter paper Characteristically, it provides a filter for separating heavy metals and a method for purifying wastewater using the filter. The filter of the present invention has the advantage of being able to separate heavy metals by ion.

Description

Alginate liquid filter and waste water purification method using the same}

The present invention relates to an alginate liquid filter and a wastewater purification method using the same.

With the current use of metals in various fields, the treatment of heavy metals in industrial wastewater has become an important problem worldwide. If heavy metal ions flow into rivers or seas as they are, the damage to the environment is very great. Heavy metals that flow into the water not only destroy the marine ecosystem such as fish, but also come up along the food chain and threaten our bodies. Therefore, there is a need for a more efficient heavy metal removal method.

Currently, the most commonly used method in sewage treatment plants for treating industrial wastewater is chemical precipitation. The existing heavy metal treatment method is a method of precipitating heavy metals in wastewater using hydroxide ions at pH in a basic state and removing them by sedimentation and separation. This method has a simple process, but the disadvantage is that there is no selectivity depending on the type of heavy metals. there is. That is, it is difficult to collect heavy metal deposits by type. Because of this, many valuable metal resources have been landfilled and discarded in the form of sludge. This process seriously pollutes the environment and makes it impossible to economically use resources. Therefore, in order to solve these problems, it is necessary to recover heavy metals from wastewater in a new way.

Republic of Korea Patent No. 0906742

The present invention has been devised to solve the above-mentioned needs in the prior art, and heavy metal separation capable of separating and recovering heavy metal ions for each ion by overcoming the disadvantage of the conventional industrial wastewater treatment method having no selectivity according to the type of heavy metal. It is an object of the present invention to provide a filter and a method for purifying wastewater using the same.

However, the technical problem to be achieved by the present invention is not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention is a filter for heavy metal separation using alginic acid,

The filter includes a plurality of filter units,

The filter parts include alginic acid solutions of different concentrations,

The filter parts provide a filter for separating heavy metals, characterized in that they are separated through filter paper.

In one embodiment of the present invention, the filter includes a first filter unit; a second filter unit; a third filter unit; And the fourth filter unit is characterized in that it has a sequentially stacked structure.

In another embodiment of the present invention, the first filter part includes an alginate solution at a concentration of 0.1 to 0.3% by weight,

The second filter part includes an alginate solution at a concentration of 0.35 to 0.55% by weight,

The third filter part includes an alginate solution at a concentration of 0.6 to 0.85% by weight,

The fourth filter unit is characterized in that it comprises an alginate solution of 0.9 to 1.2% by weight concentration.

In another embodiment of the present invention, the filter paper is characterized in that it has pores with a size of 0.1 to 30 μm.

In another embodiment of the present invention, the first filter part and the second filter part are separated by filter paper having pores of 6 to 10 μm,

The second filter part and the third filter part are separated by filter paper having pores of 2 to 3 μm,

The third filter unit and the fourth filter unit are characterized in that they are separated by filter paper having pores of 2 to 3 μm.

In another embodiment of the present invention, the heavy metal is characterized in that at least one selected from the group consisting of copper, iron, cobalt and nickel.

In addition, the present invention provides a method for purifying wastewater, comprising passing the wastewater through a filter.

As an embodiment of the present invention, the filter is connected to a power supply unit to move heavy metal ions in wastewater through electrophoresis.

The filter for separating heavy metals of the present invention can separate heavy metal ions contained in wastewater through a difference in affinity with alginic acid, and has the advantage of being able to separate them into single ions and recycle them.

1 is a diagram schematically illustrating a conventional method for treating wastewater containing heavy metals.
2 is a view showing the principle of forming an alginate gel of the present invention.
3 is a view showing the structure of a filter and an electrophoresis device used for heavy metal separation in an embodiment of the present invention.
4 is a diagram showing a comparison of affinity between heavy metal ions and alginic acid.
5 is a diagram showing a comparison of copper ion removal efficiency using the filter of the present invention and an alginate liquid.
6 is a view showing the structure of the heavy metal separation filter of the present invention.
7 is a view showing the results of confirming the formation of an alginate gel according to the concentration of an alginate solution in the heavy metal separation filter of the present invention.
8 is a view showing the results of confirming the formation of alginate gel according to the pores of the filter paper in the filter of the present invention.
9 is a diagram showing the concentration of an alginate solution according to the filter part and the pore size of the filter paper separating the filter part in the filter of the present invention.
10 is a diagram showing a process of separating copper and cobalt ions using the filter of the present invention.
11 is a diagram showing a process of separating copper and nickel ions using the filter of the present invention.
12 is a view showing a process of separating copper and iron ions using the filter of the present invention.
13 is a view showing the process of separating copper, cobalt, and iron ions using the filter of the present invention and the results of XPS analysis of the separated alginate gel.

As shown in FIG. 1, the conventional heavy metal treatment method mainly used a method of precipitating heavy metals in wastewater using hydroxide ions at a basic pH and removing them by sedimentation and separation. In this case, since heavy metals cannot be separated by type, heavy metals have no choice but to be landfilled in the form of sludge. Accordingly, the present inventors studied a method for separating heavy metals by type, and paid attention to alginic acid. Alginic acid, the main component of brown algae of the family of wakame, quickly combines with divalent cations to form a gel network (FIG. 2), and the formation of the gel appears differently depending on the affinity between alginate and metal ions.

Accordingly, an object of the present invention is to provide a heavy metal separation filter that separates metal ions using the difference in affinity between alginic acid and metal divalent ions. Since heavy metal ions are mostly divalent or trivalent ions, it will be possible to separate and recover heavy metal ions for each ion if the difference in affinity with alginic acid can be accurately identified and quantified. Therefore, a concentration gradient of the alginate solution was developed, and a filter for separating heavy metals composed of a plurality of filter parts was developed. In the filter of the present invention, when heavy metal ions flow in one direction by means of electrophoresis, heavy metal ions can be separated more easily due to a difference in affinity with alginic acid.

In addition, since the solution containing heavy metals and the alginic acid solution should not mix with each other, the filter parts were separated using filter paper by obtaining a hint from the salt bridge of the chemical cell.

Alginate gel contains a lot of water, and the water contained in the gel is evaporated, but the gel hardens more as a significant amount of water escapes. By recovering the water thus drained, waste of water can be minimized, and since the water released from the gel has a very low concentration of heavy metals, it can be recycled again. Although sewage sludge has a high water content, less water escapes, but the water that escapes from sewage sludge is still contaminated water, and when the sewage sludge dries, there is a problem of generating dust. On the other hand, alginate gel does not generate dust and has environmentally friendly decomposition characteristics.

In addition, the alginate gel can be made into a liquid state again from a gel state by using a sodium citrate solution. This is because the cross-linking of the alginate gel is broken while ion exchange between sodium and heavy metal occurs. Then, the heavy metal ions obtained through the "liquid filter" can be recovered in an ionic state, and if heavy metal ions that polluted a large amount of water can be recovered as high concentration ions in a small amount of tube and recycled back to the industry, it is a good thing. can achieve the effect of

Accordingly, the present invention is a filter for heavy metal separation using alginic acid,

The filter includes a plurality of filter units,

The filter parts include alginic acid solutions of different concentrations,

The filter parts are separated through filter paper, providing a filter for separating heavy metals:

In addition, the present invention provides a wastewater purification method comprising the step of passing the wastewater through the filter.

In one embodiment of the present invention, the filter includes a first filter unit; a second filter unit; a third filter unit; And it may be characterized in that the fourth filter unit has a sequentially stacked structure. The filter units form a concentration gradient by including alginate solutions of different concentrations, and accordingly, heavy metals can be separated according to types.

More specifically, the first filter part contains an alginate solution at a concentration of 0.1 to 0.3% by weight, the second filter part contains an alginate solution at a concentration of 0.35 to 0.55% by weight, and the third filter part contains an alginate solution at a concentration of 0.6 to 0.85% by weight. % concentration of the alginate solution, and the fourth filter unit may contain an alginate solution of 0.9 to 1.2% by weight. Copper ions may be separated from the first filter unit, iron ions may be separated from the second filter unit, cobalt ions may be separated from the third filter unit, and nickel ions may be separated from the fourth filter unit.

In addition to the first to fourth filter parts, a fifth filter part, a sixth filter part, etc. may be further included, and the concentration of the alginate solution of the filter parts may vary depending on the type of heavy metal ion to be separated. .

In another embodiment of the present invention, the filter paper may have pores with a size of 0.1 to 30 μm. In more detail, the top of the filter (ie, the top of the first filter part) includes a filter paper of 12 to 15 μm, and the first filter part and the second filter part are separated by filter paper having pores of 6 to 10 μm, , The second filter unit and the third filter unit are separated by filter paper having pores of 2 to 3 μm, and the third filter unit and the fourth filter unit are separated by filter paper having pores of 2 to 3 μm, , Filter paper having pores of 0.1 to 30 μm may be provided at the lowermost end of the filter (ie, the lower end of the fourth filter unit). The filter paper included in the lowermost part of the filter is not limited to the pore range, and general kente paper or the like may be used.

In another embodiment of the present invention, the heavy metal may be copper, iron, cobalt, nickel, calcium, magnesium, etc., but is not limited thereto.

The filter of the present invention is connected to a power supply unit and can separate heavy metal ions from each filter unit by moving heavy metal ions in wastewater through electrophoresis. A cathode of the power supply unit may be connected to an upper portion of the filter, and an anode thereof may be connected to a lower portion of the filter. The wastewater is injected through the inlet at the top of the filter, and ions may move from the top to the bottom of the filter.

Hereinafter, an embodiment of the present invention will be described in detail. However, the following examples are only to illustrate the present invention, and the content of the present invention is not limited to the following examples.

[Example]

<Experiment method>

1. Comparison of the degree of alginate gel formation according to the type of heavy metal divalent ion

To prepare an alginate liquid filter, first, the degree of alginate gel formation (affinity) according to the type of heavy metal divalent ion was compared. 1% sodium alginate solution and 100 mL of 10 mM FeSO ₄ , CuSO ₄ , CoCl ₂ , NiSO ₄ , CaCl ₂ , MnCl ₂ , MgCl ₂ solutions were prepared respectively. After pouring 50 mL of 1% alginate solution into a petri dish with a diameter of 90 mm, 15 mL of each of the 7 heavy metal solutions was added, and after 2 hours, a gel was observed. 100 mL of 1% sodium alginate solution was added to 500 mL of 10 mM CuSO ₄ , and the concentration of the copper solution was measured at 10-minute intervals using a spectrophotometer (Spectrophotometer, wavelength=635 nm). This was an experiment to compare the affinity between alginate and heavy metal ions, and at the same time to confirm the heavy metal removal effect of the alginate gel formed when no electricity was applied.

2. Measurement of copper ion removal efficiency using an alginate liquid filter

First, to make an alginate liquid filter, a power supply and an electrophoresis device (Bio rad) were prepared, and a filter structure made of acrylic and three types of filter paper were prepared. (Order made by Hyundai Micro Co., Ltd., pore size No.200: 2-3 μm, No.10: 6-10 μm, No.22: 12-15 μm) (FIG. 3).

Next, copper ion removal efficiency using an alginate liquid filter was measured. An "alginate liquid filter" was installed in the electrophoresis device, distilled water (a small amount of NaC ₂ H ₃ O ₂ added, electrolyte) was put on the cathode (-) side, and 10mM CuSO ₄ solution was put on the anode (+) side. Electricity was supplied at 80V, and the concentration of the copper solution was measured at 10-minute intervals using a spectrophotometer. (Spectrophotometer, wavelength=635 nm)

3. Confirmation of separation patterns for each heavy metal ion using an alginate liquid filter

In order to find out whether ion separation is possible using the fact that the affinity for alginate is different depending on the type of divalent heavy metal, the separation pattern of each heavy metal ion was confirmed using an alginate liquid filter. By using the concentration of the alginate solution and the filter paper (ordered by Hyundai Micro Co., Ltd.) as variables in the "alginate liquid filter", various types of liquid filter combinations were made, and the pattern of gel formation for each heavy metal shown in Table 1 below was Observed. (Table 1) The concentration of the alginate solution was fixed for each ion, and the formation of the alginate gel was observed and analyzed by varying the pore size of the filter paper. In addition, the filter paper pore size was fixed for each ion, and the alginate gel was observed and analyzed by varying the concentration of the alginate solution.

Metal Ion Concentration of Alginate solution Filter Paper Pore Size Cu 0.25% No.200: 2~3 μm Fe 0.5% No.10: 6-10 µm Co 0.75% No.22: 12~15 μm Ni One%

4. Separation of heavy metal ions using an alginate liquid filter and confirmation of metal ion separation using XPS

Based on the results of the previous experiment, Cu ²⁺ and Co ²⁺ , Cu ²⁺ and Fe ²⁺ , and Cu ²⁺ and Ni ²⁺ were separated from the solution containing the two heavy metals using an alginate liquid filter. In addition, each ion was separated from a solution in which Cu ²⁺ , Co ²⁺ , and Fe ²⁺ were mixed. The gel containing the ions separated in the experiment was dried and analyzed using an XPS device to determine which ions were contained in abundance.

5. Recovery of copper ions from alginate gel

Finally, recovery conditions and recovery rates of metal ions from alginate gels were tested. Alginate gel was added to sodium citrate solution and dissolved in a rocking shaker for 1 hour. At this time, it was important to find the optimal concentration of the sodium citrate solution. The concentration of Cu ²⁺ ions in the dissolved solution was measured using a spectrophotometer, and the recovery rate was calculated.

<result>

1. Comparison of the degree of alginate gel formation according to the type of heavy metal divalent ion

Depending on the type of metal divalent, the properties of alginate gel are different. Copper and calcium ions make gels fast and very hard, while manganese ions and iron ions make gels slow and flabby, so alginate gels cannot be properly formed. Magne?? The ions did not gel at all (FIG. 4).

This is because the affinity between alginic acid and metal divalent ion is different, and this difference is the basis for the possibility of metal ion separation using alginate.

2. Comparison of copper ion removal efficiency using alginate liquid filter

The method of mixing 100 mL of 1% alginate gel with 500 mL of 10 mM CuSO ₄ solution reduced about 18% of copper ions in 2 hours, and the "alginate liquid filter" method reduced about 44.5% of copper ions for the same time. Decreased. Although direct comparison is difficult due to differences in structure and method, it can be confirmed that the "alginate liquid filter" method has a higher speed and higher copper ion removal efficiency than the conventional mixing method (FIG. 5).

3. Confirmation of separation patterns for each heavy metal ion using an alginate liquid filter

First, the structure of the alginate liquid filter made in this embodiment is shown in FIG.

For the concentration gradient of the alginate solution, it was divided into 4 compartments, and the alginate solution was not mixed using filter paper. This is an application of the "salt bridge" of a chemical cell, allowing ions to pass through without mixing the solution. The concentration of the alginate solution and the pore size of the filter paper can be adjusted according to the type of metal ion.

3.1. Separation pattern of each metal ion according to the difference in alginate concentration

First, the separation pattern for each metal ion according to the difference in alginate concentration was confirmed (FIG. 7). First, in the case of iron ions, as the iron ions passed through the alginate liquid filter for 90 minutes, the movement speed of iron ions slowed down as the concentration of alginate increased. At a concentration of 0.25%, a gel was formed in the third compartment of the filter, but as the concentration increased, the distance at which the gel was formed became shorter. In addition, as the concentration of alginate increased, more alginate gel was produced, and the color was very vivid.

The pattern seen in the iron ion also appeared in the cobalt ion. The difference is that the point where the alginate gel is made is more to the left than the iron ion. As confirmed in Figure 4, it is determined that the phenomenon appeared because the affinity with alginate is higher than the cobalt ion.

Nickel ions formed a gel, albeit weakly, but the color was not distinct, unlike iron and cobalt ions. It was difficult to accurately determine the distance the ions traveled because it was light green, close to transparent. Looking at the formation of the gel, the amount of gel produced increased as the alginate concentration increased, and it was confirmed that the gel was formed from the first column of the filter. The overall pattern showed the same aspect as iron and cobalt ions.

Because copper ions have a very high affinity for alginate, gels were formed at the beginning of the first column of the filter at all concentrations. When the affinity with alginate was high, a gel was formed at a low concentration, and when the affinity was low, a gel was formed at a high concentration.

3.2. Separation pattern of metal ions according to filter paper pore size difference

Thereafter, the separation pattern for each metal ion due to the difference in the size of the pores of the filter paper was confirmed. In the case of iron, as the pore size increases, the movement speed of ions increases. In addition, as the pore size increases, the amount of ions passing through increases, making the gel better and the color darker and more distinct. The gels in all three pore sizes were characterized by being made at an alginate concentration of 0.75%. Therefore, it was found that the concentration of alginate is a very important factor in forming a gel.

Even in the case of cobalt, the gels in all three filter papers were made at the same location. Iron ions moved faster when the pore size increased, but there was no significant difference in cobalt ions compared to iron ions. It can be predicted that cobalt ions have a higher affinity for alginate than iron ions, so that the gel is formed from the beginning of operation of the alginate filter, and the difference in migration speed disappears. As the pore size increased, the gel was made better and the color was very distinct. Therefore, it was confirmed that the pore size is a factor that controls the passage of ions.

4. Separation of heavy metal ions using an alginate liquid filter and confirmation of metal ion separation using XPS

Since the core principle is to separate metal ions using the difference in affinity between alginate and metal ions, metal ions with high affinity to alginate are first captured while gels are formed, and metal ions with low affinity migrate farther to obtain higher concentrations. It was designed to bind with alginic acid.

Since the alginate liquid filter uses the electrophoresis method, electrophoresis was performed on copper ions and a mixed solution of copper and cobalt ions using agarose gel, which is commonly used in electrophoresis, as a comparison object. When only one type of copper ion was subjected to electrophoresis, the copper ion migrated through the gel and was not trapped in the gel. When time passes and no agarose gel is present, the copper ions will come out again into the water. When electrophoresis was performed when copper and cobalt ions were mixed, the agarose gel moved in the form of a mixture of the two ions (Fig. 10, agarose gel).

On the other hand, in the case of using an alginate liquid filter, copper ions formed a gel with 0.25% alginate solution on the surface of the first filter paper, and cobalt ions formed a gel not on the surface of the first filter paper but in the entire compartment containing the 0.25% alginate solution. did. In the side view, the color of the alginate gel made of copper and cobalt ions is clearly visible. In addition, when the prepared alginate gel was taken out and examined, a gel showing a clear blue and pink color was made, and no traces of mixing of the two ions could be observed (FIG. 10, alginate liquid filter).

In the case of separation of copper and nickel ions, copper ions also formed a gel with 0.25% alginate on the surface of the first filter paper, and nickel ions formed a gel in the entire compartment containing 0.5% alginate solution. In the side view, the color of the alginate gel made of copper and nickel ions was clearly shown as blue and light green. In addition, when the prepared alginate gel was taken out and examined, the gel showing blue and light green was clearly made, and no traces of the two ions being mixed could be seen (FIG. 11).

In the separation of copper and iron ions, a new fact was learned through the separation process. Looking at the separation process of metal ions using the alginate liquid filter over time, first, copper ions are captured while forming alginate and gel on the surface of the first filter paper, and then a yellow alginate gel of iron ions is formed on the surface of the third filter paper. that was observed It was found that copper ions had a high affinity with alginic acid and formed a blue gel immediately, and iron ions with low affinity continued to move and formed a gel when they met alginate with a relatively high concentration of 0.75%. In addition, over time, the amount of copper ion alginate gel and iron ion alginate gel increased and the color became darker. The color of the solution mixed with copper ions and iron ions was somewhat dark at the beginning, but it was confirmed that the color became lighter as the copper ions and iron ions decreased over time (FIG. 12).

This proves that the alginate liquid filter can effectively remove metal ions in water and separate each metal ion into copper ions and iron ions.

Previously, ^it was investigated whether each metal ion could be removed from a solution ^containing two types of metal ions ^. The possibility of separation by metal ion was investigated. Looking at the process of separating the three types of ions, copper ions, which have the highest affinity for alginate, are captured while forming a gel on the surface of the first filter paper, and after 30 minutes, cobalt ions, which have the highest affinity for alginic acid after copper ions, are captured. A pink gel was formed upon contact with a 0.5% alginate solution. After 60 minutes, gels of iron ions with the lowest affinity began to form, and after 90 minutes, it was confirmed that the amount of each gel increased and the color darkened (FIG. 13). It was the same as shown in the two types of metal ion separation processes prior to this, and it means that separation is possible as long as there is a difference in affinity with alginic acid.

After separating the three types of metal ions, the gel was extracted and dried, and then the metal ions in the gel were checked using XPS. As a result, it was confirmed that the metal ions were completely separated, not mixed.

5. Recovery of copper ions from alginate gel

After extracting the copper ion-alginate gel made from the alginate liquid filter, it was placed in a solution of trisodium citrate (Na ₃ C ₆ H ₅ O ₇ ) and stirred in a rocking shaker for 3 to 4 hours to dissolve the alginate gel. Therefore, it was determined that the utilization of the alginate liquid filter was quite high in that the separated ions could be recovered using the alginate gel.

10 g of alginate gel was extracted from 500 ml of 10 mM CuSO ₄ solution using an alginate liquid filter and dissolved in 40 ml of 0.3 M trisodium citrate solution to obtain a 0.04 mM copper ion solution. The recovery rate was up to 83%. The higher the concentration of trisodium citrate, the faster the alginate gel can be dissolved. However, the concentration selected to reduce the concentration of trisodium citrate as much as possible was 0.3M. By reducing the volume of trisodium citrate, a high-concentration copper ion solution can be obtained, so it can be adjusted as needed, and it is of great significance in terms of recycling metal resources.

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (8)

As a heavy metal separation filter using alginic acid,
The filter includes a plurality of filter units,
The filter parts include alginic acid solutions of different concentrations,
The filter parts are separated through filter paper,
The filter may include a first filter unit; a second filter unit; a third filter unit; And the fourth filter unit has a sequentially stacked structure,
The first filter part includes an alginate solution at a concentration of 0.1 to 0.3% by weight,
The second filter part includes an alginate solution at a concentration of 0.35 to 0.55% by weight,
The third filter part includes an alginate solution at a concentration of 0.6 to 0.85% by weight,
The fourth filter unit is characterized in that it comprises an alginate solution of 0.9 to 1.2% by weight concentration, heavy metal separation filter.
delete delete According to claim 1,
The filter paper is characterized in that it has pores of 0.1 to 30 μm in size, heavy metal separation filter.
According to claim 1,
The first filter part and the second filter part are separated by filter paper having pores of 6 to 10 μm,
The second filter part and the third filter part are separated by filter paper having pores of 2 to 3 μm,
The third filter unit and the fourth filter unit are separated by filter paper having pores of 2 to 3 μm, heavy metal separation filter.
According to claim 1,
The heavy metal is one or more selected from the group consisting of copper, iron, cobalt and nickel, heavy metal separation filter.
A method for purifying wastewater containing heavy metals, comprising passing the wastewater through the filter of claim 1.
According to claim 7,
The filter is connected to a power supply unit to move heavy metal ions in the wastewater through electrophoresis.

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