KR20200118601A - Method of Controlling Properties of Magnesium Carbonate and Method of Manufacturing Magnesium Carbonate - Google Patents

Abstract

The present invention relates to a method for controlling properties of magnesium carbonate and a method for manufacturing magnesium carbonate. The method for controlling properties of magnesium carbonate and the method for manufacturing magnesium carbonate of the present invention can predict and control the properties of magnesium carbonate manufactured without an additional post-treatment process, and thus can manufacture magnesium carbonate only with a desired property according to industrial uses, thereby being economical. In addition, since collected carbon dioxide and magnesium ions present in industrial wastewater are used, the present invention can not only reduce carbon dioxide but also treat wastewater, thereby being eco-friendly.

Description

Method of controlling properties of magnesium carbonate and method of manufacturing magnesium carbonate {Method of Controlling Properties of Magnesium Carbonate and Method of Manufacturing Magnesium Carbonate}

The present invention relates to a method for controlling the properties of magnesium carbonate and a method for producing magnesium carbonate.

Global warming and climate change are of great interest to science and engineering researchers. Global warming is known to be caused by the emission of greenhouse gases. When high concentrations of greenhouse gases are released into the atmosphere, they absorb infrared radiant energy emitted from the Earth. Greenhouse gases release absorbed energy towards the Earth's surface, increasing the average temperature of the Earth's surface. A typical greenhouse gas is carbon dioxide. Considering the global warming potential (GWP), which means the contribution of each component to global warming, and the total amount of emissions, it is reported that carbon dioxide is the largest contributor to global warming. Therefore, many studies are underway to reduce carbon dioxide emissions.

One of the most common ways to reduce carbon dioxide is to capture the carbon dioxide contained in industrial exhaust gases produced by fossil fuel combustion. In the wet absorption method, which is a representative process, carbon dioxide is collected by a liquid absorbent, and the collected carbon dioxide is separated and stored. The problem is that a large amount of energy is required to separate carbon dioxide from the absorbent. It is known that the carbon dioxide separation process requires 70 to 80% of the total energy. In addition, the stored carbon dioxide has a risk of leakage and becomes a problem because the storage space is insufficient.

In consideration of this problem, research is being conducted on another method for carbon dioxide reduction, that is, capturing and using carbon dioxide (CCU). CCU technology captures carbon dioxide and converts it into useful materials such as diesel, polymers and metal carbonates. This technology can be divided into organic and inorganic production methods in consideration of the properties of the product. The organic material production method requires a process of converting carbon dioxide into a reactive material in order to convert carbon dioxide into an organic material, and requires an expensive and effective catalyst, and energy consumption is significantly higher than that of an inorganic material production method.

On the other hand, the inorganic material production method can process a large amount of carbon dioxide compared to the organic material production method and does not require an expensive catalyst because the reactivity is higher than that of the organic material production method. In addition, when carbon dioxide is converted into metal carbonate, it can be stored semi-permanently due to its high stability, and can be used as a raw material in various industrial fields.

Until now, metal carbonate production CCU technology has focused on the production of calcium carbonate using calcium ions. However, carbon dioxide can be converted into calcium carbonate as well as various other metal carbonates. Magnesium exists in a large amount in nature, and magnesium carbonate can be a candidate because it can be used in various fields such as medicine and abrasives. However, it is difficult to prepare a desired magnesium-based product because reaction conditions for controlling the form and properties of magnesium carbonate have not been established.

S. Shen, Y. -N. Yang, Y. Bian, Y. Zhao, Environ. Sci. Technol. 2016, 50, 2054 Anand B. RaO, Edward S. Rubin, Environ. Sci. Technol. 2002, 36, 4467

Accordingly, the technical problem to be solved by the present invention is to provide a method for controlling the properties of the produced magnesium carbonate, a method for producing magnesium carbonate, and a method for recycling industrial wastewater in producing magnesium carbonate using collected carbon dioxide. .

An aspect of the present invention comprises the steps of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And reacting the alkanolamine-based absorbent solution absorbing carbon dioxide with a magnesium hydroxide solution to prepare magnesium carbonate; including, and the properties of the produced magnesium carbonate include the type of the alkanolamine-based absorbent, the alkanol A method for controlling the properties of magnesium carbonate determined according to the concentration of the amine absorbent solution, the reaction temperature, and the ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (number of moles of Mg ²⁺ ions: number of moles of Na ⁺ ions) Provides.

Another aspect of the present invention comprises the steps of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And reacting the alkanolamine-based absorbent solution absorbing the carbon dioxide with a magnesium hydroxide solution to produce magnesium carbonate. It provides a method for producing magnesium carbonate comprising:

Another aspect of the present invention is the step of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And preparing magnesium carbonate by reacting the alkanolamine-based absorbent solution absorbing carbon dioxide with a magnesium hydroxide solution; including, wherein the magnesium hydroxide is precipitated by adjusting the pH of industrial wastewater to 7.0 to 10.0 Provides a method of recycling wastewater.

Since the magnesium carbonate property control method and the magnesium carbonate production method of the present invention can predict and control the properties of magnesium carbonate produced without an additional post-treatment process, only magnesium carbonate of a desired property can be produced according to industrial use. It is economical. In addition, since the collected carbon dioxide and magnesium ions present in industrial wastewater are used, not only carbon dioxide reduction but also wastewater treatment is possible, which is environmentally friendly.

1 is a schematic diagram schematically showing a process of a refined salt production plant.
2 is a diagram showing the entire process according to an embodiment of the present invention.
3 shows the structural formula of the absorbent used in an embodiment of the present invention. (a) is monoethanolamine, (b) is 3-amino-1-propanol, (c) is 4-amino-1-butanol, (d) is 5-amino-1-pentanol, (e) is 6 -Amino-1-hexanol.
4 is a schematic diagram of a carbon dioxide absorption test apparatus according to an embodiment of the present invention.
5 is a CO ₂ adsorption curve for 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, and 6-amino-1-hexanol according to an embodiment of the present invention. Represents.
6 is an XRD pattern of a product prepared according to the use of each amine according to an embodiment of the present invention.
7 shows FT-IR curves for products using 5-amino-1-pentanol and 6-amino-1-hexanol, respectively, according to an embodiment of the present invention.
8 is an SEM image of a product produced by the use of each amine according to an embodiment of the present invention. FIG. 8A shows a case of using 3-amino-1-propanol, FIG. 8B shows 4-amino-1-butanol, FIG. 8C shows 5-amino-1-pentanol, and FIG. 8D shows 6-amino-1-hexanol.
9 is a TG/DTG curve of a product produced when different absorbents are used according to an embodiment of the present invention. FIG. 9A shows 3-amino-1-propanol, FIG. 9B shows 4-amino-1-butanol, FIG. 9C shows 5-amino-1-pentanol, and FIG. 9D shows 6-amino-1-hexanol.
10 is an XRD pattern of each product at 303.15, 313.15, 323.15, 333.15 and 343.15 K according to an embodiment of the present invention. In FIG. 10, (a) shows 303.15 K, (b) shows 313.15 K, (c) shows 323.15 K, (d) shows 333.15 K, and (e) shows magnesium carbonate produced at a reaction temperature of 343.15 K.
11 is an SEM image of magnesium carbonate produced by controlling a reaction temperature according to an embodiment of the present invention. In FIG. 11, (a) shows 303.15 K, (b) shows 313.15 K, (c) shows 323.15 K, (d) shows 333.15 K, and (e) shows magnesium carbonate produced at a reaction temperature of 343.15 K.
12 is a TG/DTG analysis curve of magnesium carbonate generated by controlling a reaction temperature according to an embodiment of the present invention. In FIG. 12, (a) is 303.15 K, (b) is 313.15 K, (c) is 323.15 K, (d) is 333.15 K, (e) is TG/DTG of magnesium carbonate produced at a reaction temperature of 343.15 K. The analysis curve is shown.
13 is an XRD analysis result of magnesium carbonate produced by controlling a carbon dioxide concentration according to an embodiment of the present invention. In Figure 13, (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the XRD analysis result of magnesium carbonate prepared using% MEA aqueous solution.
14 is an SEM analysis result of magnesium carbonate generated by adjusting the carbon dioxide concentration according to an embodiment of the present invention. In Figure 14 (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the SEM analysis result of magnesium carbonate prepared using% MEA aqueous solution.
15 shows the results of TG/DTG analysis of magnesium carbonate produced by adjusting the carbon dioxide concentration according to an embodiment of the present invention. In FIG. 15, (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the result of TG/DTG analysis of magnesium carbonate prepared using% MEA aqueous solution.
16 is an XRD analysis result of magnesium carbonate generated by adjusting the Mg ²⁺ / Na ⁺ ratio (1/5, 2/5, 3/5, 4/5, 5/5) according to an embodiment of the present invention to be. In FIG. 16, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of XRD analysis of magnesium carbonate produced in the ratio.
17 is an XRD analysis result of magnesium carbonate generated by adjusting the Mg ²⁺ / Na ⁺ ratio according to an embodiment of the present invention. In FIG. 17, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of SEM analysis of magnesium carbonate produced in the ratio.
18 is a TG/DTG of magnesium carbonate produced by adjusting the Mg ²⁺ / Na ⁺ ratio (1/5, 2/5, 3/5, 4/5, 5/5) according to an embodiment of the present invention. This is the result of the analysis. In FIG. 18, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of TG/DTG analysis of magnesium carbonate produced in the ratio.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

An aspect of the present invention comprises the steps of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And reacting the alkanolamine-based absorbent solution absorbing carbon dioxide with a magnesium hydroxide solution to prepare magnesium carbonate; including, and the properties of the produced magnesium carbonate include the type of the alkanolamine-based absorbent, the alkanol Control of the properties of magnesium carbonate determined according to the concentration of the amine absorbent solution, the reaction temperature, and the ratio of the number of moles of magnesium ions and the number of moles of sodium ions present in the magnesium hydroxide solution (Mg ^{2 +} moles of ions / Na ⁺ moles of ions) Provides a way.

Magnesium carbonate is typically present in _three properties: nesquehonite (MgCO ₃ · 3H ₂ O), hydromagnesite (Mg ₅ (CO ₃ ) ₄ (OH) ₂ · 5H ₂ O), and magnesite (MgCO ₃ ). The method of controlling the properties of magnesium carbonate of the present invention relates to a method of controlling the properties of magnesium carbonate prepared by using carbon dioxide absorbed by an alkanolamine absorbent by adjusting specific conditions.

The magnesium hydroxide may be precipitated by adjusting the pH of industrial wastewater to 7.0 to 10.0. The industrial wastewater refers to water discharged after being used in industrial activities such as agriculture, forestry, fishing, and mining. In particular, the industrial wastewater may be seawater-based industrial wastewater, and the seawater-based industrial wastewater refers to water or seawater-based liquid industrial waste that is discharged after being used in a seawater desalination or refined salt production process. Seawater-based industrial wastewater is preferred because it contains several metal cations including magnesium in a high concentration, and because magnesium exists in the form of ions, it has a high carbonation reactivity compared to other sources of magnesium such as natural minerals and solid wastes. In addition, when wastewater containing highly concentrated metal cations is discharged to seawater without treatment, it is preferable because it can negatively affect the surrounding ecosystem, and thus, wastewater treatment can be performed simultaneously with the production of magnesium carbonate.

1 is a schematic diagram schematically showing a process of a refined salt production plant, and Table 1 shows the concentration of metal cations in industrial wastewater using seawater.

Metal cations Concentration (mg/L) Molarity (mol/L) Na ⁺ 22873 0.995 Mg ²⁺ 50846 2.092 Ca ²⁺ 25132 0.628 K ⁺ 28867 0.761

Various kinds of metal ions exist in the industrial wastewater, of which magnesium forms magnesium hydroxide in a pH range of 7.0 to 10.0, so only magnesium can be separated through a pH adjustment method.

The alkanolamine-based absorbent is preferable because it has excellent ability to absorb carbon dioxide and can supply carbon dioxide in an ionic form to magnesium ions.

The alkanolamine-based absorbent may be a primary amine, and the types of the alkanolamine-based absorbent are monoethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, and 5-amino-1-pentane It may be selected from ol and 6-amino-1-hexanol.

As can be seen in the examples described below, the type of absorbent used is a condition for controlling the properties of magnesium carbonate, and more specifically, the properties of magnesium carbonate can be controlled according to the length of the alkyl chain of the primary alkanolamine. I can. For example, when monoethanolamine, 3-amino-1-propanol, and 4-amino-1-butanol having a short alkyl chain of the primary alkanolamine are selected and used, nesquehonite is formed, but alkyl It was confirmed that as the length of the chain increased, an amorphous MgCO ₃ ·3H ₂ O was formed.

In addition, the concentration of the alkanolamine-based absorbent solution may be adjusted in 5 to 30% by weight. By adjusting the concentration of the absorbent solution, the concentration of carbon dioxide injected into the magnesium carbonate production can be adjusted, and the carbon dioxide concentration affects the control of the properties of the magnesium carbonate.

The temperature of the reaction may be controlled at 20 to 100 °C, preferably at 30 to 70 °C. The temperature of the reaction refers to the temperature in the reaction of the alkanolamine absorbent solution absorbing carbon dioxide and the magnesium hydroxide solution. The temperature conditions affect the properties of the magnesium carbonate to be produced. For example, nesquehonite is formed at a temperature in the range of 20 to 50° C., and hydromagnesite is formed at a higher temperature. When the temperature of the reaction is controlled below 20°C, it is difficult to have significance in terms of industrial and practical application because it is lower than the expected temperature in the actual technology application process, and when it is controlled in a range above 100°C, energy consumption is large. There may be a problem of inefficiency due to its low energy consumption.

The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution is adjusted by adding NaCl to the magnesium hydroxide solution, and may be adjusted in the range of 0.2 to 1:1. By controlling the ratio of the number of moles of magnesium ions and sodium ions present in the magnesium hydroxide solution, properties of the produced magnesium carbonate can be controlled. The ratio of the number of moles of magnesium ions and the number of moles of sodium ions may be adjusted by adding NaCl. As can be seen in the examples described later, when the ratio is adjusted to 0.2 to 0.6:1, nesquehonite is formed, and as the ratio of magnesium ions increases, hydromagnesite is formed. Therefore, it was confirmed that the properties of magnesium carbonate can be controlled by adjusting the ratio of the number of moles of magnesium ions and the number of moles of sodium ions. If the ratio is adjusted outside the above ratio range, salting out effect may occur due to the effect of salinity, and thus the precipitation rate and purity of magnesium carbonate may be affected, which is not preferable.

Four conditions for controlling the properties of magnesium carbonate (type of alkanolamine absorbent, concentration of alkanolamine absorbent solution, reaction temperature, ratio of moles of magnesium ions and moles of sodium ions present in magnesium hydroxide solution) The description of is described the tendency of the properties of magnesium carbonate formed according to the adjustment of each condition, and more precise control of the properties can be achieved by a combination of each condition.

It is preferable that the concentration of magnesium hydroxide in the magnesium hydroxide solution is 10 to 30% by weight.

Although not explicitly described in the following Examples or Comparative Examples, etc., in the method for controlling the properties of magnesium carbonate according to the present invention, the purity of the properties of the magnesium carbonate prepared by varying various conditions of the control method and the alkanolamine type used The reusability of the absorbent was confirmed.

As a result, unlike in other conditions and numerical ranges, when all of the following conditions were satisfied, it was confirmed that the purity of the intended magnesium carbonate property achieved 90% or more, and the reusability of the used absorbent was significantly increased. . In particular, it was difficult for hydromagnesite to achieve high purity despite the control of various conditions, but it was confirmed that hydromagnesite was also produced with a high purity of 90% or more when the properties of magnesium carbonate were controlled under the following conditions.

(I) The magnesium hydroxide is precipitated by adjusting the pH of industrial wastewater to 9.0 to 10.0, (ii) the concentration of the alkanolamine-based absorbent solution is adjusted at 13 to 17% by weight, (iii) the temperature of the reaction Is adjusted at 65 to 75°C, (iv) the ratio of the number of moles of magnesium ions and the number of moles of sodium ions present in the magnesium hydroxide solution is adjusted by adding NaCl to the magnesium hydroxide solution, and is adjusted in the range of 0.8 to 1: 1, (v ) The magnesium hydroxide concentration of the magnesium hydroxide solution is 10 to 30% by weight.

However, when any of the above conditions was not satisfied, it was confirmed that the purity of the intended magnesium carbonate property was lowered or the reusability of the used absorbent was lowered.

Another aspect of the present invention comprises the steps of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And reacting the alkanolamine-based absorbent solution absorbing the carbon dioxide with a magnesium hydroxide solution to produce magnesium carbonate. It provides a method for producing magnesium carbonate comprising:

The alkanolamine-based absorbent may be 3-amino-1-propanol or 4-amino-1-butanol, and the magnesium carbonate may be nesquehonite. Among the primary alkanolamine-based absorbents, when 3-amino-1-propanol or 4-amino-1-butanol, which has a relatively short alkyl chain length, was used as an absorbent, it was confirmed that nesquehonite was formed, and the chain length increased. In the case of 5-amino-1-pentanol or 6-amino-1-hexanol, it can be confirmed that amorphous MgCO ₃ ·3H ₂ O is formed.

The reaction temperature is 30 to 50° C., and the magnesium carbonate may be nesquehonite. In addition, the reaction temperature may be 65 to 100° C., and the magnesium carbonate may be hydromagnesite. In the reaction of magnesium hydroxide and an alkanolamine-based absorbent solution absorbing carbon dioxide, nesquehonite may be formed when the reaction temperature is 30 to 50°C, and hydromagnesite may be formed at 65 to 100°C. At a temperature of 50 to 65° C., nesquehonite and hydromagnesite are formed at the same time, which is not preferable as a temperature for producing magnesium carbonate of a specific property.

The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (number of moles of Mg ²⁺ ions: number of moles of Na ⁺ ions) is 0.1 to 0.7: 1, and the magnesium carbonate may be nesquehonite. In addition, the ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (number of moles of Mg ²⁺ ions: number of moles of Na ⁺ ions) is 0.75 to 1:1, and the magnesium carbonate may be hydromagnesite. The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution can be adjusted by adding NaCl. When the mole ratio is 0.1 to 0.7:1, nesquehonite is formed, and in 0.75 to 1:1, hydromagnesite is formed.

Another aspect of the present invention is the step of absorbing carbon dioxide in an alkanolamine-based absorbent solution; And preparing magnesium carbonate by reacting the alkanolamine-based absorbent solution absorbing carbon dioxide with a magnesium hydroxide solution; including, wherein the magnesium hydroxide is precipitated by adjusting the pH of industrial wastewater to 7.0 to 10.0 Provides a method of recycling wastewater. The method of recycling industrial wastewater is eco-friendly in that industrial wastewater can be used as a source of magnesium ions, and thus industrial wastewater can be recycled and at the same time, industrial wastewater can be treated. As described above, the industrial wastewater refers to water discharged after being used in industrial activities such as agriculture, forestry, fishing, and mining, and is preferably a seawater-based industrial wastewater. Seawater-based industrial wastewater refers to water or seawater-based liquid industrial waste that is discharged after being used in seawater desalination and refined salt production processes. Seawater-based industrial wastewater is preferred because it contains several metal cations including magnesium in a high concentration, and because magnesium exists in the form of ions, it has a high carbonation reactivity compared to other sources of magnesium such as natural minerals and solid wastes.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention. However, these examples are for describing the present invention in more detail, and the scope of the present invention is not limited thereto, and various changes and modifications are possible within the scope and spirit of the present invention. It will be self-evident to those who have knowledge.

Example.

Materials used

All materials were purchased and used from Sigma-Aldrich. Sodium hydroxide (purity ≥ 97.0 wt%, CAS No. 1310-73-2), sodium chloride (NaCl, purity ≥ 99 wt%, CAS No. 7647-14-5), and magnesium hydroxide (Mg(OH) ₂ ,purity≥ 99 wt%, CAS No. 1309-42-8) was used without further purification. Monoethanolamine (MEA, purity ≥ 99 wt%, CAS No. 141-43-5), 3-amino-1-propanol (3-amino-1-propanol, C ₃ H ₉ NO, purity≥ 99 wt. %, CAS No. 156-87-6), 4-amino-1-butanol (4-amino-1-butanol, C ₄ H ₁₁ NO, purity≥ 98 wt%, CAS No. 13325-10-5), 5-amino-1-butanol (5-amino-1-pentanol, C ₅ H ₁₃ NO, purity≥ 95 wt%, CAS No. 2508-29-4) and 6-amino-1-butanol (6-amino- 1-hexanol, C ₆ H ₁₅ NO, purity≥ 97 wt%, CAS No. 4048-33-3) was used as an experimental material to investigate the effect of the length of the alkyl chain. 3 shows the chemical structural formula of each amine.

Experimental method

Through carbon dioxide capture and conversion experiments, the effects of the alkyl chain length, temperature, carbon dioxide concentration and Mg ²⁺ / Na ⁺ ratio of the primary alkanolamine absorbent on the formation of magnesium carbonate were measured.

First, a carbon dioxide absorption experiment was performed using the apparatus shown in FIG. 4 to control the above conditions. 4 is a schematic diagram of a carbon dioxide absorption test apparatus according to an embodiment of the present invention.

First, the detailed process of the absorption experiment is as follows. The main composition of the device is a mass flow controller (MFC, SH151019-328, KOFLOC), a mass flow manager (MFM), a gas mixer, a reactor, a gas analyzer (Multi Master SR3121211, Sensoronic Co., Ltd.) and a gas (N ₂ , It is composed of CO ₂ and high purity N ₂ ).

Using MFC and MFM, the concentration of injected CO ₂ was constantly adjusted and adjusted to the desired ratio. In general, since the concentration of carbon dioxide in the exhaust gas discharged from a coal-fired power plant is in the range of 10 to 20% by volume, the carbon dioxide concentration was set to have an average value of 15% by volume. The volume flow rates of injected N ₂ and CO ₂ were 1775 and 300 ml/min, respectively. In addition, the gas analyzer measured the carbon dioxide concentration of the final gas discharged from the reactor. In order to supply a uniform concentration of simulated gas to the reactor, a gas mixer was installed between the MFC and the reactor. By controlling the valve between the gas mixer and the reactor, the timing of injection of the simulated gas into the reactor could be controlled. In order to ensure the accuracy of the injected CO ₂ concentration, impurities and residual moisture in the reactor were removed through nitrogen purging. When the gas analyzer showed 0 vol% of CO ₂ concentration for 30 minutes, gas injection was started through valve control. Since the reactor has the form of a double jacketed reactor, the reaction temperature could be kept constant and controlled using a water bath. The inside of the reactor was uniformly stirred at 300 rpm by a magnetic stirrer and a stir bar. The simulated gas generated by the gas mixer was diffused into the absorbent through the gas diffuser and reacted with the absorbent. In this process, the reactor was regarded as a semi-batch reactor, and the gas released from the reactor was analyzed with a gas analyzer. A condenser and a cooler were installed at the top of the reactor and maintained at 263.15 K to prevent changes in the concentration of the absorbent due to evaporation. Gas analyzes in the CO ₂ concentration Marking 15% by volume means that the absorbent can no longer absorb CO ₂ , so the absorption experiment is terminated.

Next, a carbonation process was performed. In the carbonation process, in order to utilize the Mg ²⁺ ions contained in the seawater-based wastewater of the refined salt production plant, magnesium ions were separated in the form of Mg(OH) ₂ through a pH swing method using NaOH. 200 g of the separated 20 wt% Mg(OH) ₂ slurry was added to a carbon dioxide saturated alkanolamine absorbent, and a conversion experiment was performed. Stirring was carried out for 3 hours. In the above experiment, (1) the alkyl chain length of the primary alkanolamine, (2) the reaction temperature, (3) the CO ₂ concentration, and (4) the Mg ²⁺ /Na ⁺ ratio were adjusted. First, 15% by weight of each of 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-butanol and 6-amino-1-butanol in order to control the alkyl chain length of the primary alkanolamine , 400 g was used.

Second, the temperature range at which the reaction between the Mg(OH) ₂ slurry and the CO ₂ saturated absorbent was performed was controlled to 303.15, 313.15, 323.15, 333.15, and 343.15 K. The temperature was maintained during the carbonation process as well as the carbon dioxide capture process.

Thirdly, monoethanolamine of various concentrations (MEA, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% and 30 wt%) CO ₂ concentration by the method of absorbing CO ₂ using Has been adjusted.

Finally, the ratio of Mg ²⁺ /Na ⁺ ions is 1/5 (Mg(OH) ₂ 0.2 mol/ NaCl 1 mol), 2/5 (Mg(OH) ₂ 0.4 mol/ NaCl 1 mol), 3/5 (Mg(OH) ₂ 0.6 mol / NaCl 1 mol), 4/5 (Mg(OH) ₂ 0.8 mol / NaCl 1 mol) and 5/5 (Mg(OH) ₂ 1 mol / NaCl 1 mol) were used. . Since a lot of NaCl is contained in seawater-oriented industrial wastewater, it is easy to control the ratio of Mg ²⁺ /Na ⁺ ions, so it can be used in the design of an actual CCU plant connected to a refined salt production plant.

All conditions except those controlled in each part were fixed to the same condition. The absorbent used was 15 wt% MEA, the reaction temperature was 303.15 K, the CO ₂ concentration was 1.303 x 10 ^-3 mol CO ₂ /g, 20 wt% Mg(OH) ₂ aqueous slurry, which is a value using 400 g of 15 wt% MEA 200 g were each added to the CO ₂ saturated absorbent.

The mixed solution in which Mg(OH) ₂ and CO ₂ saturated absorbent components were mixed was filtered using a filter paper and a vacuum pump. Further, the filtered product was dried in a heating oven at a temperature of 353.15 K for 24 hours.

Condition 1. Property control according to alkyl chain length control

Carbon dioxide adsorption experiments were conducted to confirm the carbon dioxide adsorption capacity of each absorbent, and the carbon dioxide absorption value (mol CO ₂ /mol amine) was derived from the carbon dioxide concentration data of the gas analyzer. 5 is a CO ₂ adsorption curve for 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, and 6-amino-1-hexanol according to an embodiment of the present invention. Represents. In addition, Table 2 shows the CO ₂ absorption values and reusability of the CO ₂ capture process for each amine in the first absorption, desorption and second absorption steps.

Amine type CO ₂ loadinginabsorption
(mol CO ₂ /molamine) Reusability (%) 3-amino-1-propanol 1 ^st absorption 0.6825 54.26 2 ^nd absorption 0.3703 4-amino-1-butanol 1 ^st absorption 0.6469 92.49 2 ^nd absorption 0.5983 5-amino-1-pentanol 1 ^st absorption 0.7152 60.18 2 ^nd absorption 0.4304 6-amino-1-hexanol 1 ^st absorption 0.8449 50.01 2 ^nd absorption 0.4225

The first absorption, desorption and second absorption experiments were shown in each section of FIG. 5, respectively. The CO ₂ uptake was calculated by the following equation:

(mol)는 흡수제에 의해 흡수된 CO₂의 양,

(mol/min)는 모의 가스의 CO₂ 몰 유량,

(vol%)는 모의 가스의 CO₂ 부피 농도,

(vol%) 는 가스 분석기의 출구와 연결된 CO₂ 부피 농도, Δt (min)은 가스 분석기의 측정 시간, n_a (mol)은 아민의 몰수이다.here

(mol) is the amount of CO ₂ absorbed by the absorbent,

(mol/min) is the CO ₂ molar flow rate of the simulated gas,

(vol%) is the volume concentration of CO ₂ in the simulated gas,

(vol%) is the volume concentration of CO ₂ connected to the outlet of the gas analyzer, Δt (min) is the measurement time of the gas analyzer, and n _a (mol) is the number of moles of amine.

The reusability of each amine was measured through a second absorption experiment. It was confirmed that CO ₂ absorption tends to increase as the length of the alkyl chain increases in the _first absorption period. 4-Amino-1-butanol showed the lowest CO ₂ absorption in the _first absorption period, but the highest CO ₂ absorption in the _second absorption period. That is, 4-amino-1-butanol showed the best results in terms of reuse of the absorbent in the CO ₂ capture part in the CCU process.

In FIG. 5, the gap between the equilibrium point of the first absorption section and the first desorption section refers to the amount of CO ₂ converted to metal carbonate. In this way, a conversion rate for each amine was induced by the ratio of the amount of absorbed CO ₂ dae CO ₂ conversion amount in the first absorption zone. Table 3 below shows the carbon dioxide conversion rate. In the extension of the excellent results for reusability, 4-amino-1-butanol showed the highest conversion rate (59.00%). According to these absorption properties, 4-amino-1-butanol was the best absorbent in terms of capacity as an absorbent for CCU applications.

Amine type The amount of the CO ₂ converted(mol) Conversion yield (%) 3-amino-1-propanol 0.2370 34.73 4-amino-1-butanol 0.3817 59.00 5-amino-1-pentanol 0.2322 32.47 6-amino-1-hexanol 0.2626 31.08

Magnesium carbonate is typically present in _three properties: nesquehonite (MgCO ₃ · 3H ₂ O), hydromagnesite (Mg ₅ (CO ₃ ) ₄ (OH) ₂ · 5H ₂ O), and magnesite (MgCO ₃ ).

6 is an XRD pattern of a product prepared according to the use of each amine according to an embodiment of the present invention. In FIG. 6, a circle represents an XRD pattern of nesquehonite, an inverted triangle represents an XRD pattern of brucite, Mg(OH) ₂ , and a square represents an XRD pattern of hydromagnesite. According to Figure 6, the product using 3-amino-1-propanol and 4-amino-1-butanol shows peaks of nesquehonite and brushite, but 5-amino-1-pentanol and 6-amino-1 The product using -hexanol showed only the peak of brushite. That is, formation of crystals could not be confirmed by detection using 5-amino-1-pentanol and 6-amino-1-hexanol. Therefore, FT-IR (Vertex 70, Bruker) was performed on the product prepared using 5-amino-1-pentanol and 6-amino-1-hexanol in order to determine the presence or absence of magnesium carbonate. 7 shows FT-IR curves for products using 5-amino-1-pentanol and 6-amino-1-hexanol, respectively, according to an embodiment of the present invention. Both products showed similar patterns, including peaks of Mg(OH) ₂ and magnesium carbonate in the FT-IR curve. In FIG. 7, a yellow line indicates the presence of Mg(OH) ₂ , and a green line indicates the presence of amorphous MgCO ₃ ·3H ₂ O. Green lines showed peaks at wavenumbers 850, 1105 and 1430 cm ^-1 , indicating the presence of carbonate ions and amorphous MgCO ₃ ·3H ₂ O. In addition, it had a peak at 1520 cm ^-1 , which means unidentate of MgCO ₃ . From the above results, it was found that amorphous magnesium carbonate was formed prior to the formation of crystals such as nesquehonite, hydromagnesite, and magnesite, and produced when 5-amino-1-pentanol and 6-amino-1-hexanol were used. It was confirmed that amorphous magnesium carbonate was formed.

The crystal structure of each product was analyzed through SEM. 8 is an SEM image of a product produced by the use of each amine according to an embodiment of the present invention. FIG. 8A shows a case of using 3-amino-1-propanol, FIG. 8B shows 4-amino-1-butanol, FIG. 8C shows 5-amino-1-pentanol, and FIG. 8D shows 6-amino-1-hexanol. While it was possible to confirm the shape of the Nesquehonite rod in FIGS. 8A and 8B, it was confirmed that the rod shape was not in FIGS. 8C and 8D. This is a result demonstrating the formation of amorphous MgCO ₃ ·3H ₂ O demonstrated by XRD and FT-IR.

TG/DTG analysis was performed to investigate the purity of each product. TG/DTG analysis was performed at a temperature increase rate of 10° C./min. 9 shows a TG/DTG curve of a product produced when different absorbents are used according to an embodiment of the present invention, and the results are shown in Table 4 below. FIG. 9A shows 3-amino-1-propanol, FIG. 9B shows 4-amino-1-butanol, FIG. 9C shows 5-amino-1-pentanol, and FIG. 9D shows 6-amino-1-hexanol.

Amine type Form of magnesium carbonate Purity (wt%) 3-amino-1-propanol Nesquehonite
(MgCO ₃ · 3H ₂ O) 49.24 4-amino-1-butanol Nesquehonite
(MgCO ₃ · 3H ₂ O) 63.05 5-amino-1-pentanol Amorphous MgCO ₃ ·3H ₂ O 38.36 6-amino-1-hexanol Amorphous MgCO ₃ ·3H ₂ O 43.38

As can be seen in FIGS. 9 and 4, it was found that among the absorbents, 4-amino-1-butanol not only showed superiority in the carbon dioxide absorption portion, but also had the highest purity. When 5-amino-1-butanol and 6-amino-1-hexanol were used, it was confirmed that amorphous magnesium carbonate could be prepared.

Condition 2. Property control according to reaction temperature

XRD analysis was performed to measure the components of the product according to temperature control. 10 is an XRD pattern of each product at 303.15, 313.15, 323.15, 333.15 and 343.15 K according to an embodiment of the present invention. In FIG. 10, (a) shows 303.15 K, (b) shows 313.15 K, (c) shows 323.15 K, (d) shows 333.15 K, and (e) shows magnesium carbonate produced at a reaction temperature of 343.15 K. As can be seen in FIG. 10, when the reaction temperature is 303.15, 313.15, and 323.15 K, nesquehonite and brucite were generated, whereas when the reaction temperature is 333.15 K, nesquehonite, brucite and hydromagnesite were generated. Could be confirmed. At 343.15 K, only hydromagnesite and brushite were detected.

11 is an SEM image of magnesium carbonate produced by controlling a reaction temperature according to an embodiment of the present invention. In FIG. 11, (a) shows 303.15 K, (b) shows 313.15 K, (c) shows 323.15 K, (d) shows 333.15 K, and (e) shows magnesium carbonate produced at a reaction temperature of 343.15 K.

As can be seen in FIG. 11, rod-shaped nesquehonite appeared at 303.15, 313.15 and 323.15K, and 333.15 K showed three types of magnesium carbonate. At 343.15 K, it was confirmed that most of the crystals were hydromagnesite. The SEM analysis result was consistent with the XRD measurement result.

According to the XRD and SEM results, the purity of magnesium carbonate for each product was analyzed through TG/DTG analysis. 12 is a TG/DTG analysis curve of magnesium carbonate generated by controlling a reaction temperature according to an embodiment of the present invention. In FIG. 12, (a) is 303.15 K, (b) is 313.15 K, (c) is 323.15 K, (d) is 333.15 K, (e) is TG/DTG of magnesium carbonate produced at a reaction temperature of 343.15 K. The analysis curve is shown. In the TG/DTG analysis, the temperature increase rate was 10°C/min, and the analysis results are shown in Table 5.

As a result of analysis, the product of 303.15 K contained nesquehonite of 90.82 wt% purity, and the products of 313.15 and 323.15 K contained 60.33 and 63.49 wt% of nesquehonite. At 333.15 K the product contained 40.85 wt% pure nesquehonite and 12.72 wt% pure hydromagnesite. The product of 343.15 K had hydromagnesite with a purity of 91.70% by weight.

Temperature (K) Form of magnesium carbonate Purity (wt%) 303.15 Nesquhonite
(MgCO ₃ · 3H ₂ O) 90.82 313.15 Nesquehonite
(MgCO ₃ · 3H ₂ O) 60.33 323.15 Nesquehonite
(MgCO ₃ · 3H ₂ O) 63.49 333.15 Nesquehonite
(MgCO ₃ · 3H ₂ O) 40.85 Hydromagnesite
(Mg ₅ (CO ₃ ) ₄ (OH) ₂ 5H ₂ O) 12.72 343.15 Hydromagnesite
(Mg ₅ (CO ₃ ) ₄ (OH) ₂ 5H ₂ O) 91.70

The product at 303.15 K contained a higher purity nesquehonite, while at 313.15 and 323.15 K a relatively low purity nesquehonite was formed. Some of the nesquehonite of the 333.15 K product was transformed into hydromagnesite, and at 343.15 K, most of the nesquehonite was transformed into hydromagnesite. Through the above results, it was confirmed that the properties of magnesium carbonate can be controlled by temperature control.

Condition 3. Property control according to carbon dioxide concentration

13 is an XRD analysis result of magnesium carbonate produced by controlling a carbon dioxide concentration according to an embodiment of the present invention. In Figure 13, (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the XRD analysis result of magnesium carbonate prepared using% MEA aqueous solution.

In the XRD analysis, all products had nesquehonite and brushite peaks. The presence of brushite means the presence of unreacted Mg(OH) ₂ . That is, the above result means that the carbon dioxide concentration does not affect the formation of hydromagnesite and magnesite, but only affects the formation of nesquehonite.

14 is an SEM analysis result of magnesium carbonate generated by adjusting the carbon dioxide concentration according to an embodiment of the present invention. In Figure 14 (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the SEM analysis result of magnesium carbonate prepared using% MEA aqueous solution. In FIG. 14, impurities such as nesquehonite, brushite, and unwashed amine can be clearly identified. In addition, as can be seen in FIG. 14, relatively many impurities were observed at a low carbon dioxide concentration, because the absolute amount of carbon dioxide was insufficient. In addition, there was no difference in the size of nesquehonite in each product. Based on this, it could be confirmed that carbon dioxide does not have a decisive effect on the size of nesquehonite.

In addition, TG/DTG analysis was performed to analyze the purity of the product according to the carbon dioxide concentration control. 15 shows the results of TG/DTG analysis of magnesium carbonate produced by adjusting the carbon dioxide concentration according to an embodiment of the present invention. In FIG. 15, (a) is 5% by weight, (b) is 10% by weight, (c) is 15% by weight, (d) is 20% by weight, (e) is 25% by weight, (f) is 30% by weight This is the result of TG/DTG analysis of magnesium carbonate prepared using% MEA aqueous solution.

Based on the theoretical carbon dioxide absorption of MEA, 400 g of 5, 10, 15, 20, 25 and 30% by weight MEA aqueous solutions absorbed 0.174, 0.347, 0.521, 0.695, 0.868 and 1.042 moles of carbon dioxide. In addition, 20% by weight of the Mg(OH) ₂ slurry has 0.686 moles of Mg(OH) ₂ . These results and the properties of magnesium carbonate formation according to the carbon dioxide concentration are shown in Table 6 below.

Used MEA concentration CO ₂ concentration (10 ^-3 mol CO ₂ /g solution) Form of magnesium carbonate Purity (wt%) 5 wt% 0.435 Nesquehonite
(MgCO ₃ · 3H ₂ O) 55.91 10 wt% 0.868 Nesquehonite
(MgCO ₃ · 3H ₂ O) 70.70 15 wt% 1.303 Nesquehonite
(MgCO ₃ · 3H ₂ O) 91.43 20 wt% 1.738 Nesquehonite
(MgCO ₃ · 3H ₂ O) 88.12 25 wt% 2.17 Nesquehonite
(MgCO ₃ · 3H ₂ O) 83.94 30 wt% 2.61 Nesquehonite
(MgCO ₃ · 3H ₂ O) 80.99

In the case of using 5, 10, and 15% by weight of the MEA aqueous solution in Table 6, the tendency between the amount of carbon dioxide provided and the purity could be confirmed. However, in 20, 25, 30% by weight of MEA aqueous solution, the tendency could not be confirmed. This is because the formation of nesquehonite is hindered by relatively large carbonate ions in a high concentration volume.

Condition 4. Mg ²⁺ / Na ⁺ Constellation control according to ratio adjustment

16 is an XRD analysis result of magnesium carbonate generated by adjusting the Mg ²⁺ / Na ⁺ ratio (1/5, 2/5, 3/5, 4/5, 5/5) according to an embodiment of the present invention to be. In FIG. 16, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of XRD analysis of magnesium carbonate produced in the ratio.

As can be seen in (a) and (b) of Figure 16, in the products of Mg ²⁺ / Na ⁺ ratio 1/5 and 2/5, nesquehonite and halite were observed. On the other hand, it was confirmed that hydromagnesite and brushite were observed in the products of Mg ²⁺ / Na ⁺ ratio 3/5, 4/5, and 5/5 in FIGS. 16 (c), (d) and (e).

SEM analysis was performed to investigate the properties of the product. 17 is an XRD analysis result of magnesium carbonate generated by adjusting the Mg ²⁺ / Na ⁺ ratio according to an embodiment of the present invention. In FIG. 17, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of SEM analysis of magnesium carbonate produced in the ratio.

The crystal shape of nesquehonite could be confirmed in FIGS. 17 (a) and (b), and the crystal shape of hydromagnesite in FIGS. 17 (c), (d) and (e). However, when the Mg ²⁺ / Na ⁺ ratio was 3/5, it was confirmed that it had a plate shape unlike the Mg ²⁺ / Na ⁺ ratio of 4/5 and 5/5.

18 is a TG/DTG of magnesium carbonate produced by adjusting the Mg ²⁺ / Na ⁺ ratio (1/5, 2/5, 3/5, 4/5, 5/5) according to an embodiment of the present invention. This is the result of the analysis. In FIG. 18, (a) is 1/5, (b) is 2/5, (c) is 3/5, (d) is 4/5, and (e) is 5/5 of Mg ²⁺ / Na ⁺ This is the result of TG/DTG analysis of magnesium carbonate produced in the ratio. The properties of magnesium carbonate according to the Mg ²⁺ / Na ⁺ ratio are shown in Table 7 below.

Mg ²⁺ /Na ⁺ ratio Form of magnesium carbonate Purity (wt%) 1/5
(Mg ²⁺ :Na ⁺ =0.2:1) Nesquehonite
(MgCO ₃ · 3H ₂ O) 99.19 2/5
(Mg ²⁺ :Na ⁺ =0.4:1) Nesquehonite
(MgCO ₃ · 3H ₂ O) 59.18 3/5
(Mg ²⁺ :Na ⁺ =0.6:1) Nesquehonite
(MgCO ₃ · 3H ₂ O) 88.10 4/5
(Mg ²⁺ :Na ⁺ =0.8:1) Hydromagnesite
(Mg ₅ (CO ₃ ) ₄ (OH) ₂ 5H ₂ O) 98.29 5/5
(Mg ²⁺ :Na ⁺ =1:1) Hydromagnesite
(Mg ₅ (CO ₃ ) ₄ (OH) ₂ 5H ₂ O) 98.49

As can be seen in Table 7, when the ratio of Mg ²⁺ / Na ⁺ was 1/5, the purity of Nesquehonite was close to 99% by weight, but when it was 2/5, it was 59.18% by weight. This is because the specific gravity of weakly hydrated Mg ²⁺ increased, which lowered the solubility of nesquehonite. In addition, when the Mg ²⁺ / Na ⁺ ratio was 3/5, the purity of the plate-shaped hydromagnesite was 88.10 wt%, and in the case of 4/5 and 5/5, the purity was 98.29 wt% and 98.49 wt%, respectively. These results can be improved by a post-treatment method such as washing with ethyl alcohol, and it was confirmed that the availability is high because of high purity.

Therefore, the method for controlling the properties of magnesium carbonate of the present invention can predict and control the properties of the produced magnesium carbonate without an additional post-treatment process, so it is economical to produce only magnesium carbonate of a desired property according to industrial use. In addition, since the collected carbon dioxide and magnesium ions present in industrial wastewater are used, not only carbon dioxide reduction but also wastewater treatment is possible, which is environmentally friendly.

The above-described Examples and Comparative Examples are examples for explaining the present invention, and the present invention is not limited thereto. Since those of ordinary skill in the art to which the present invention pertains will be able to implement the present invention by various modifications therefrom, the technical protection scope of the present invention should be determined by the appended claims.

Claims (16)

Absorbing carbon dioxide in an alkanolamine-based absorbent solution; And
Including; reacting the alkanolamine-based absorbent solution absorbing the carbon dioxide with a magnesium hydroxide solution to produce magnesium carbonate; Including,
The properties of the prepared magnesium carbonate include the type of the alkanolamine absorbent, the concentration of the alkanolamine absorbent solution, the reaction temperature, and the ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (Mg ²⁺ The number of moles of ions: Na ^{+ the number} of moles of ions) to control the properties of magnesium carbonate. The method of claim 1,
The magnesium hydroxide is precipitated by adjusting the pH of industrial wastewater to 7.0 to 10.0. The method for controlling the properties of magnesium carbonate. The method of claim 1,
The alkanolamine-based absorbent is a method for controlling the properties of magnesium carbonate, which is a primary amine.
The method of claim 1,
The type of the alkanolamine absorbent is any selected from monoethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, and 6-amino-1-hexanol A method for controlling the properties of magnesium carbonate, which is one or a mixture of two or more.
The method of claim 1,
A method for controlling the properties of magnesium carbonate in which the concentration of the alkanolamine-based absorbent solution is adjusted at 5 to 30% by weight.
The method of claim 1,
A method for controlling the properties of magnesium carbonate in which the temperature of the reaction is controlled at 20 to 100°C.
The method of claim 1,
The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution is controlled by adding NaCl to the magnesium hydroxide solution, and is controlled in the range of 0.2 to 1:1.
The method of claim 1,
The magnesium hydroxide solution has a magnesium hydroxide concentration of 10 to 30% by weight of the magnesium carbonate property control method.
The method of claim 1,
The magnesium hydroxide is precipitated by adjusting the pH of industrial wastewater to 9.0 to 10.0,
The concentration of the alkanolamine-based absorbent solution is adjusted in 13 to 17% by weight,
The temperature of the reaction is controlled at 65 to 75 °C,
The ratio of the number of moles of magnesium ions and the number of moles of sodium ions present in the magnesium hydroxide solution is adjusted by adding NaCl to the magnesium hydroxide solution, and is adjusted in the range of 0.8 to 1:1,
The magnesium hydroxide solution has a magnesium hydroxide concentration of 10 to 30% by weight of the magnesium carbonate property control method.
Absorbing carbon dioxide in an alkanolamine-based absorbent solution; And
A method for producing magnesium carbonate comprising: reacting the alkanolamine-based absorbent solution absorbing carbon dioxide with a magnesium hydroxide solution to produce magnesium carbonate.
The method of claim 10,
The alkanolamine-based absorbent is 3-amino-1-propanol or 4-amino-1-butanol,
The magnesium carbonate is nesquehonite, a method for producing magnesium carbonate.
The method of claim 10,
The temperature of the reaction is 20 to 50 ℃,
The magnesium carbonate is nesquehonite, a method for producing magnesium carbonate.
The method of claim 10,
The temperature of the reaction is 65 to 100 ℃,
The magnesium carbonate is a method for producing magnesium carbonate, which is hydromagnesite.
The method of claim 10,
The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (number of moles of Mg ²⁺ ions: number of moles of Na ⁺ ions) is 0.1 to 0.7: 1,
The magnesium carbonate is nesquehonite, a method for producing magnesium carbonate.
The method of claim 10,
The ratio of the number of moles of sodium ions to the number of moles of magnesium ions present in the magnesium hydroxide solution (number of moles of Mg ²⁺ ions: number of moles of Na ⁺ ions) is 0.75 to 1: 1,
The magnesium carbonate is a method for producing magnesium carbonate, which is hydromagnesite. Absorbing carbon dioxide in an alkanolamine-based absorbent solution; And
Including; reacting the alkanolamine-based absorbent solution absorbing the carbon dioxide with a magnesium hydroxide solution to produce magnesium carbonate; including,
The magnesium hydroxide is a method of recycling industrial wastewater that is precipitated by adjusting the pH of industrial wastewater to 7.0 to 10.0.

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