KR102656602B1 - Methods of preparing magnesium silicate for food - Google Patents

Abstract

The present invention includes the steps of mixing and stirring water glass, nonionic surfactant, and oil to prepare a stable emulsion solution; Preparing a magnesium precursor solution; Preparing a gelling agent solution; Preparing a magnesium solution by mixing a magnesium precursor solution and a gelling agent; Dropping the emulsion solution into a magnesium solution; Reacting by heating at 75-85°C for 3-4 hours; phase separation step; A method for producing magnesium silicate including washing and drying magnesium silicate is provided. According to the method of the present invention, in the process of using a W/O emulsion system using water glass, nonionic surfactant, and oil, the particle size and particle size of the magnesium silicate are adjusted, and the purification speed and acid value reduction performance are adjusted accordingly. Magnesium silicate can be manufactured.

Description

Method for producing magnesium silicate for food {Methods of preparing magnesium silicate for food}

The present invention relates to a method for producing magnesium silicate, using water glass as a raw material, using a w/o emulsion system, and reacting the water glass emulsion with a magnesium solution dropwise.

Magnesium silicate is in powder form and is used as an adsorbent or purification in various fields such as food and medicine.

Methods for synthesizing magnesium silicate include precipitation, hydrothermal precipitation, and mechano-chemical dehydration. The double precipitation method is the easiest synthesis method for mass production with low production costs. It is synthesized by reacting water-soluble magnesium salt and soluble sodium silicate in an aqueous solution to precipitate and separate the insoluble salt magnesium silicate and then drying it.

Magnesium silicate for food refers to synthetic magnesium silicate that satisfies the standards recognized by International Standard No. INS No: 533(i). Mainly in the food industry, when cooking oil is used to fry dishes, it adsorbs and removes impurities (color, odor, acid value) caused by the oxidation of the cooking oil, thereby prolonging the use of the cooking oil. The American company DALLAS GROUP does not disclose the method of synthesizing magnesium silicate for food, but it is presumed to produce it using a dry spray method. This method has the advantage of simple raw materials as micro-unit granulation is achieved through a physical method, but it has the disadvantage of being difficult to wash with water during the process and having fine particles block the filter due to an unspecified particle distribution, thereby lowering the purification speed.

In Republic of Korea Patent No. 10-1841581, nanoparticles with a particle size of nanoscale are also formed among the magnesium silicate precipitate generated, thereby solving the problem of reducing productivity by blocking the micropores of the filter and lengthening the filtration process to separate the precipitate. To this end, a process for producing magnesium silicate that does not require a separate filtration process is disclosed by supplying magnesium salt to the sodium silicate solution through a nozzle to form magnesium silicate in the nozzle. However, there is a problem with this in that there is a need to scrape off the magnesium silicate formed in the nozzle. In addition, the magnesium silicate produced with the above patent has the disadvantage of poor filtration performance and dispersibility because the particle shape or particle size distribution is irregular.

Accordingly, while trying to develop a product that can control the particle size and purification performance of magnesium silicate by applying a method of emulsifying and precipitating water glass particles, the present invention was arrived at.

In the present invention, in the method of producing magnesium silicate by dropping droplets of water glass from a W/O emulsion system using water glass, nonionic surfactant, and oil, the particle size and particle size are controlled to determine the acid value in the purification of waste cooking oil. The aim is to provide a method for producing magnesium silicate with adjustable dropping performance and purification speed.

The present invention includes the steps of mixing and stirring water glass, nonionic surfactant, and oil to prepare a stable emulsion solution; Preparing a magnesium precursor solution; Preparing a gelling agent solution; Preparing a magnesium solution by mixing a magnesium precursor solution and a gelling agent; Dropping the emulsion solution into a magnesium solution; Reacting by heating at 75-85°C for 3-4 hours; phase separation step; A method for producing magnesium silicate including washing and drying magnesium silicate is provided.

According to the present invention, water glass is used as a raw material, a W/O emulsion system is used, and the water glass emulsion solution is added dropwise to the magnesium solution to react in one step. In the process, the reaction conditions are adjusted to control the particle shape and particle size of the magnesium silicate produced. This can be done, and the purification performance of magnesium silicate can be adjusted accordingly.

1 is a process flow diagram of the manufacturing method of the present invention.
Figure 2 is an SEM photograph of magnesium silicate of Examples and Comparative Examples.
Figure 3 is a summary of PSA (particle size analysis) of the magnesium silicate of Example 1 and Comparative Example 1.
Figure 4 shows the results of SEM-EDS (scanning electron microscopy-energy dispersive X-ray spectrometry) analysis of the magnesium silicate of Example 1 and Comparative Example 1.

The present invention is a process using a W/O emulsion system in synthesizing magnesium silicate, specifically, mixing and stirring water glass, nonionic surfactant, and oil to prepare a stable emulsion solution; Preparing a magnesium precursor solution; Preparing a gelling agent solution; Preparing a magnesium solution by mixing a magnesium precursor solution and a gelling agent; Dropping the emulsion solution into a magnesium solution; Reacting by heating at 75-85°C for 3-4 hours; phase separation step; A method for producing magnesium silicate including washing and drying magnesium silicate is provided.

The water glass is composed of Na ₂ O·nSiO ₂ (n = 2 to 4) and a small amount of Fe ₂ O ₃ and has a moisture content of 10 to 30%. Water glass is strongly alkaline, and silica gel is made by neutralizing it with acid and drying the precipitate. In the present invention, the pores of the magnesium silicate produced can be adjusted by adjusting the concentration of water glass, which is a raw material.

The preferred concentration of the water glass proposed in the present invention is to be contained in the range of 14.5 to 22.13% (SiO ₂ % w/w %) based on the SiO ₂ content in the water glass.

Additionally, when stirring water glass, surfactant, and oil, the emulsion particle size can be adjusted depending on temperature, stirring speed, type of surfactant, and concentration of surfactant/oil. The range for each condition is described as follows. The temperature ranges from 10 to 60°C, the stirring speed ranges from 300 to 1000 rpm, and the surfactant/oil concentration ranges from 5 to 15%.

Typical examples of the oil include kerosene or paraffin oil, and diesel p-xylene, hexane, or mixtures thereof can be used. The weight ratio of the mixed solution of oil and surfactant and water glass can be 0.34 to 1.

A surfactant is a substance that is adsorbed on the surface of a liquid to increase the activity of the interface and significantly change its properties. In the present invention, it serves to prevent cohesion between droplets of the water glass solution within the emulsion and to stabilize the droplets of the water glass solution. . In the present invention, nonionic surfactants are used as surfactants, specifically (sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, and sorbitan One or more of these surfactants selected from the group consisting of monolaurate (sorbitan monolaurate) may be included in the emulsion in a weight range of preferably 0.16 to 3%.

The oil and surfactant are first mixed, then water glass is added and stirred to form a stable emulsion. To stabilize the emulsion, stirring is preferably performed for 10 to 30 minutes at the stirring speed range described above. At this time, the physical energy (stirring force) applied to the emulsion is stored as surface energy and has the characteristic of being maintained as an emulsion even after several hours. Additionally, the size of the emulsion spheres is determined by the stirring speed, temperature of each fluid, concentration of water glass, and concentration of surfactant, and the size ranges from 3 to 100㎛.

The magnesium solution is prepared by mixing a gelling agent solution with a magnesium precursor solution. As a magnesium precursor, hexahydrate or heptahydrate hydrate of magnesium salts such as Mg(NO ₃ ) ₂ and MgSO ₄ are used. First, make an aqueous solution of 10 to 50% by weight of magnesium precursor. Next, 10 to 30% by weight of gelling agent solution is mixed to complete the preparation of the magnesium solution. The mixing ratio of the magnesium precursor solution and the gelling agent solution is 0.3 to 0.4:1 by volume.

The emulsion solution is quickly added dropwise to the magnesium solution prepared in this way. During the dropwise addition, the reaction temperature is 10 to 60°C and the mixture is stirred at a speed of 40 to 150 rpm. At this time, the stirrer is a general stirrer.

There are two ways to mix the emulsion solution and the magnesium solution: dropping the magnesium solution into the emulsion solution and dropping the emulsion solution into the magnesium solution. In the present invention, a method of dropping the emulsion solution into the magnesium solution is used. The method of dropping the emulsion solution into the magnesium solution has the advantage of stable precipitation in experiments. This is because the density of the emulsion solution is relatively lower than that of the magnesium solution, so the emulsion floats inside the magnesium solution. Because of this, the reaction does not occur immediately. When the reaction occurs through heat and stirring energy, it is dispersed relatively consistently, enabling a stable reaction. . Therefore, the present invention preferably proposes a method of dropping the emulsion solution into the magnesium solution.

After the dropwise addition is completed, the temperature of the magnesium solution containing the dropwise emulsion is maintained for 30 to 40 minutes while maintaining the stirring speed and reaction temperature, and then heated at 85°C for 3 to 4 hours. At this time, continue to stir.

As the temperature rises, the stored surface energy achieves phase separation, and the temperature at this time is called the temperature at which the hydrophilic and lipophilic properties are in balance (PIT, Phase Inversion Temperature). In the above reaction, the PIT range is reached in the range of 30~50℃ and almost completely separated when it reaches 75℃. In the emulsion solution (SiO ₂ + oil + surfactant) dropped in the PIT range, the lipophilic phase (oil + surfactant) separates into layers and moves to the upper layer due to the density difference. At that moment, the remaining water glass droplets immediately react with the hydrophilic phase (magnesium, gelling agent) and gel into a spherical shape.

When the reaction is complete, two phases exist: the upper layer is an oil and surfactant layer, and the lower layer is a layer containing water and solids. At this time, only the water and solids in the lower layer are drawn downward by using the density difference between water and oil. And the oil and surfactant in the upper layer are transported separately for recycling.

Next, the solids contained in the lower layer are compressed and then washed with water. Wash until the conductivity of the washing water reaches 150~250 mS/m. Through this process, magnesium silicate in solid state is obtained, and finally, they are dried (moisture 10% or less) to complete the production of magnesium silicate of the present invention. The washing is done with water (tap water, industrial water). The drying may be accomplished through a box oven, hot air drying, or microwave drying process.

The magnesium silicate of the present invention prepared in this way can preferably be used as an adsorbent or purification of edible oil.

Hereinafter, the present invention will be described in more detail through examples.

Example 1

Magnesium silicate was prepared according to the process shown in Figure 1.

1. Preparation of emulsion solution

Water glass No. 3 (sodium silicate, Ilshin Chemical, silica content 28 to 30% by weight, SiO ₂ :Na ₂ O = 3.52:1) and distilled water were diluted to prepare a water glass solution with a SiO ₂ content of 14.5% by weight. The total amount was 200 kg.

Add 4 kg of span 80 as a surfactant to 25 kg of kerosene, stir thoroughly, and then add it to the water glass solution prepared previously. An emulsion solution was prepared by stirring using a homomixer (45°C, 500rpm).

2. Preparation of magnesium solution

Next, a 22% by weight aqueous solution of MgSO ₄ (hepta hydr.) was prepared inside the reaction tank, and then a 10% aqueous solution of NH ₄ HCO ₃ was added and stirred. The mixing ratio of 22% by weight aqueous solution of MgSO ₄ (hepta hydr.) and 10% aqueous solution of NH ₄ HCO ₃ was set at 0.3:1 by volume. At this time, the total amount of this mixture is 245 kg. The magnesium solution thus prepared was heated to 40°C.

3. Reaction between emulsion solution and magnesium solution

Next, the prepared emulsion solution was added dropwise to the magnesium solution. At this time, the stirring speed was 80 rpm and the reaction temperature was 40°C for 30 minutes. After dropping, it was heated at 80°C for 3 hours.

4. Phase separation

After heating, the stirring speed was reduced to allow phase separation of kerosene + surfactant (upper layer) and water + solids (lower layer). Solid-liquid separation was carried out by transferring water and solids from the lower layer. The kerosene + surfactant remaining in the upper layer of the reactor was transferred to another tank for recycling.

5. Water washing

The separated solids were compressed and washed repeatedly with washing water until the washing water containing the solids showed a conductivity of 200 mS/m or less.

6. Dry

The washed solid was dried until the moisture content was 10% to finally obtain magnesium silicate.

Example 2

Magnesium silicate was prepared in the same manner as in Example 1, except that MgSO ₄ (haptahydr) was used instead of Mg(NO ₃ ) ₂ (hexahydr).

Example 3

Magnesium silicate was prepared in the same manner as in Example 1, except that the reaction temperature was 20°C instead of 40°C.

Example 4

Magnesium silicate was prepared in the same manner as in Example 1, except that the reaction temperature was 30°C instead of 40°C.

Example 5

Magnesium silicate was prepared in the same manner as in Example 1, except that the reaction temperature was 50°C instead of 40°C.

Example 6

Magnesium silicate was prepared in the same manner as in Example 1, except that 90% MgSO ₄ and 10% Mg(NO ₃ ) ₂ were used as magnesium precursors.

Example 7

Magnesium silicate was prepared in the same manner as in Example 1, except that 70% MgSO ₄ and 30% Mg(NO ₃ ) ₂ were used as magnesium precursors.

Example 8

Magnesium silicate was prepared in the same manner as in Example 1, except that the emulsification stirring speed was 1,000 rpm instead of 500 rpm.

Comparative Example 1

Magnesol XL (Dallas, USA) was used as magnesium silicate.

1. Magnesium silicate characterization

The properties of magnesium silicate of the above examples and comparative examples were analyzed, and these are shown in Figures 2 to 4.

Figure 2 is a SEM (scanning electron microscope) photograph of the magnesium silicate of Examples and Comparative Examples. Magnesium silicate prepared according to the present invention varies in sphericity depending on the reaction temperature and has the highest sphericity at 40°C, but at lower temperatures. It was confirmed that the sphericity decreased again at high temperatures. In addition, it was confirmed that spherical particles were formed in Examples 1 and 2, respectively, where MgSO ₄ and Mg(NO ₃ ) ₂ were used as magnesium precursors, but that spherical particles were not formed well in Examples 6 and 7, where both precursors were used together.

Figure 3 is a summary of PSA (particle size analysis) of magnesium silicate in Example 1 and Comparative Example. According to the results in Figures 2 and 3, the diameter of the magnesium silicate prepared in Example 1 was found to be approximately 31.45 ㎛ on average.

Figure 4 shows the results of scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS) analysis of the magnesium silicate prepared in Example 1 and Comparative Example 1. According to the results, the magnesium contents of Example 1 and Comparative Example 1 were 9.34 and 10.51 Wt%, respectively.

2. Edible oil refining performance evaluation

The purification performance (purification speed and acid value reduction when refining waste cooking oil) of the magnesium silicate prepared in the above example and the comparative example product was compared and evaluated.

200 g of trivalent cooking oil (Oleic acid) was added to a 300 ml round bottom flask, 2 g of the magnesium silicate prepared above was added, and the mixture was heated to 200° C. while stirring at a speed of 200 rpm. The mixture was maintained at a temperature of 200° C. with stirring for 30 minutes.

To evaluate the purification speed, cool the mixture to 100°C, place a paper filter (pie) in the heated Buchner funnel, pour all of the mixture, and measure the time from when the first drop falls until the first drop of cooking oil forms using a stopwatch. recorded.

Next, to measure the acid value, 20 g of the passed cooking oil was placed in a 200 ml Erlenmeyer flask, and 30 ml of a mixture of ether and ethanol was added and dissolved. After adding 2-3 drops of 1% phenolphthalein ethanol and adding 0.1N KOH ethanol solution, this experiment was conducted with the end point being when light red color persisted for 30 seconds to measure the appropriate consumption amount. At the same time, a blank test was conducted in the same manner as above under the condition that no sample was added.

The acid value was calculated using the following formula:

V2: Appropriate consumption amount of 0.1N KOH.Ethanol solution in ml in this experiment

V1: Appropriate consumption amount of 0.1N KOH.Ethanol solution in blank test, ml

F: Titer of 0.1N KOH.Ethanol solution:1.020

S: Sample collection amount (g)

The evaluation results are shown in Table 1 below.

Comparative Example 1 is an internationally recognized magnesium silicate for food. Compared to this, in the case of Example 1, the amount of acid value reduction was superior to that of Comparative Example 1, and the purification speed was also significantly superior due to the sphericalization of the particles. In Example 8, when the emulsification speed rpm was increased from 500 to 1000, the acid value reduction performance improved, but the purification speed decreased due to the smaller particle size. Therefore, it can be seen that in the present invention, the purification speed can be controlled by controlling the emulsification speed. Additionally, according to the magnesium silicate production method of the present invention, the shape of the particles could be controlled by controlling the reaction temperature. And, as confirmed in Examples 1 and 2, spherical particles are advantageous for filter speed, while when the particles are spherical and large, the cooking oil purification speed is fast, but the larger the particles, the smaller the specific surface area, so the purification performance is lower than the acid value. Decrease performance decreases. Therefore, the method presented in the present invention has the advantage of being able to produce customized magnesium silicate according to purification requirements by controlling the emulsification speed, reaction temperature, and type of magnesium precursor.

Claims (11)

Water glass, nonionic surfactant, and oil are mixed so that the weight ratio of the mixed solution of oil and surfactant and water glass is 0.34 to 1, and stirred at a temperature of 10 to 60 ℃ at a speed of 300 to 1000 rpm to form a stable emulsion solution. manufacturing step;
Preparing a magnesium precursor solution using hexahydrate or heptahydrate hydrate of magnesium salts such as Mg(NO ₃ ) ₂ and MgSO ₄ as a magnesium precursor;
Preparing a gelling agent solution;
Preparing a magnesium solution by mixing the magnesium precursor solution and the gelling agent;
Adding the emulsion solution to the magnesium solution dropwise at a temperature of 30 to 40°C and stirring at a low speed of 40 to 150 rpm;
Reacting by heating at 75-85°C for 3-4 hours;
phase separation step;
A method for producing magnesium silicate comprising washing and drying magnesium silicate. In paragraph 1:
A method for producing magnesium silicate, characterized in that the water glass has a concentration in the range of 14.5% to 22.13% (SiO ₂ % w/w %) based on the SiO ₂ content in the water glass. In paragraph 1:
The surfactant is one selected from the group consisting of sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, and sorbitan monolaurate. A method for producing magnesium silicate, characterized by the above. In paragraph 1:
A method for producing magnesium silicate, characterized in that the oil is kerosene, paraffin oil, diesel p-xylene, hexane, or a mixture thereof. delete delete delete In paragraph 1:
A method of producing magnesium silicate, characterized in that after the dropping is completed, the temperature is reached at 75-85°C and then heated at that temperature for 3-4 hours. In paragraph 1:
In the phase separation step, the lower layer is collected from the upper layer of oil + surfactant and the lower layer of water + solids. In paragraph 9:
In the washing step, condensed solids are obtained from the lower layer and washed with washing water, and at this time, washing is performed until the conductivity of the washing water becomes 200 mS / m or less. A method of producing magnesium silicate. In paragraph 10:
A method for producing magnesium silicate, characterized in that drying the washed solids until the moisture content is 10% or less.