JP2000053963A - Dealkalized water glass solution, and method for producing dealkalized water glass solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alkali-removed water glass solution having an SiO2 concentration of a specific value or larger, a special ratio of a specified value or larger and an alkaline property, substantially not affecting environments, capable of being simply processed into liquids, and suitable as a main agent for alkali-free silica sol-based ground-improving agents having excellent durability. SOLUTION: This alkali-removed water glass solution has an SiO2 concentration of >=1 wt.%, an SiO2/X2O molar ratio of >=6 (X is an alkali metal) and pH 7-12, and is preferably obtained by subjecting water glass to an electrodialysis treatment using an ion exchange membrane as a diaphragm to remove alkali components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a de-alkali water glass solution suitable as a main ingredient of a non-alkali silica sol-based soil improver which has a small influence on the surrounding environment, is easy to prepare, and has excellent durability. It relates to the manufacturing method.

[0002]

2. Description of the Related Art In civil engineering work and the like, a chemical solution for improving a ground by injecting a ground improvement injection material from the outside into a ground which may be collapsed due to excavation or a ground which is difficult to excavate due to spring water or the like. The construction method is general-purpose.

[0003] Various ground improvement injection materials are known, but the ground improvement injection material mainly composed of water glass is inexpensive and the gel time can be easily adjusted. .

Recently, the solidified material obtained by injection has a high strength and is excellent in durability, the injection solution is a single solution, the gel time can be easily adjusted, and the handling is easy. The type of foreign matter that elutes from the solidified material after ground improvement is limited and has a small effect on the environment. Alkaline silica sol ground improvement injection material is often used.

The acidic non-alkali silica sol obtained by the sodium silicate-acid reaction is economical because an acid, particularly inexpensive sulfuric acid, is used as a raw material, and water glass is also inexpensive.

[0006]

However, in this non-alkali silica sol ground improvement injection material, since a large amount of alkali ions are contained in the water glass, the reaction material is simply added to the water glass and stirred. If it is performed only, gel will be generated in the stirring tank, and the production cannot be performed. In order to solve this problem, it is necessary to use a particularly strong acid as a reactant, and slowly dilute the water glass into the strong acid and stir the solution to prepare the solution in a very complicated manner. Under such circumstances, a special production apparatus is required to continuously produce a liquid at the construction site.

[0007] Furthermore, this ground improvement injection material has a low pH range of 3 or less for obtaining a usable gel time,
Therefore, before and after the solidification of the ground, acids and alkali metal salts derived from the injection material flow out of the solidified material, lowering the pH of the groundwater and increasing the salt concentration and electrical conductivity, at least affecting the surrounding environment. May give.

On the other hand, since the conventional non-alkali silica sol uses sulfuric acid as a reactant, sulfate ions are formed as sulfates in pore water having a skeletal structure after gelation as shown in the following reaction (1). Dissolve.

[0009]

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When the solidified non-alkali silica sol comes into contact with groundwater, its sulfate ions are easily eluted.
When a concrete structure exists in or near the ground improvement area, sulfate ions in the groundwater infiltrate into the concrete structure, and as shown in the reaction formulas (2) to (4), Reacts with hydrated components to form expandable ettringite. The expansion pressure at the time of this generation may cause cracking and collapse of the concrete.

[0011]

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[0012]

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[0013]

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Therefore, it is conceivable to suppress the amount of acid or sodium salt eluted and to reduce the amount of acid mixed with water glass for use in a more neutral region. In addition, it is difficult to harden the mixture, and furthermore, the injection time having a sufficient strength such as an extremely short gel time cannot be obtained.

Therefore, in order to reduce the influence of acid after injection and consolidation, and to minimize the outflow of water-soluble alkali metal salts, a ground improvement injection material mainly composed of water glass with a low alkali content must be used. No

Therefore, the main object of the present invention is to provide a method for removing a molar ratio (S) obtained by an alkali removal method such as an electrodialysis method.
Ground improvement by obtaining a dealkalized water glass solution having iO ₂ / X ₂ O, X: alkali metal) of 6 or more, using this as a main material, and using one or both of an organic acid and an inorganic acid as a reaction material It is used as an injection material.

[0017]

According to the first aspect of the present invention, which solves the above-mentioned problems, the present invention has a SiO ₂ concentration of 1% by weight or more and a molar ratio of SiO ₂ / X ₂ O (X: alkali metal) of 6%. As described above, a dealkalized water glass solution characterized in that the pH is in the range of 7 to 12.

According to a second aspect of the present invention, water glass is electrodialyzed using an ion exchange membrane as a diaphragm, and an alkali component is dealkalized. The SiO ₂ concentration is 1 wt% or more, and SiO ₂ / X ₂ O is used. It is a dealkalized water glass solution characterized in that the molar ratio of (X: alkali metal) is 6 or more and the pH is in the range of 7 to 12.

[0019] According to a third aspect, the water glass is passed through a cation exchange resin and ion exchange of alkali metal components, it is obtained by de-alkali treatment, SiO ₂ concentration 1w
It is a dealkalized water glass solution characterized by having a molar ratio of SiO ₂ / X ₂ O (X: alkali metal) of 6 or more and a pH in the range of 7 to 12 at least t%.

According to a fourth aspect of the present invention, an anode and a cathode are disposed at both ends of an electrodialysis tank, and a cation exchange membrane and an anion exchange membrane are alternately positioned between the anode and the cathode to form a concentration chamber and Desalting chambers are formed alternately, and while each of the electrodes is energized, a water glass aqueous solution is passed through the desalting chamber, and a sodium hydroxide aqueous solution or potassium hydroxide aqueous solution is passed through the concentrating chamber to perform electrodialysis. , SiO ₂ concentration is 1
wt% or more, a molar ratio of SiO ₂ / X ₂ O (Na or K) of 6 or more, and a pH of 7 to 12 to obtain an aqueous solution of dealkalized water glass. is there.

According to a fifth aspect of the present invention, there is provided the method for producing a dealkalized water glass according to the fourth aspect, wherein the aqueous sodium hydroxide solution or the aqueous potassium hydroxide solution contains a chelating agent for sequestering.

According to a sixth aspect of the present invention, the chelating agent for sequestering includes disodium ethylenediaminetetraacetate, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, propylenediaminetetraacetic acid, bis ( The method for producing a dealkalized water glass according to claim 5, wherein the method is selected from the group consisting of (2-hydroxyphenylacetic acid) ethylenediamine, a salt thereof, and two or more kinds thereof.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments and experimental examples.

(Regarding Alkali Removal Method) <Ion-exchange resin method> From the viewpoint described in the section of the problem to be solved by the invention, an ion-exchange resin is used as a method for directly removing alkali components in No. 3 water glass. A possible dealkalization method is considered. This ion exchange method is a method in which a water glass solution is passed through a cation exchange resin layer to exchange sodium ions with hydrogen ions.

For example, a commercially available macroporous strong acid cation exchange resin (manufactured by Organo: Amberlite IR)
-120B) was charged into a cylindrical experimental apparatus, and No. 3 water glass diluted to 5% of SiO ₂ concentration was passed through the same amount as the resin volume, and alkali-removed water glass (active silica) was recovered from the lower part.

The activated silica recovered by passing the No. 3 water glass is colorless and transparent and is the same as the diluted water glass, but is unstable. The SiO ₂ concentration is about ₂ to 4.5 (depending on the passage time), and the molar ratio is 1030.
１1160, pH about 3, gel time about 70 hours, soil gel time 0.8 minutes, sand gel strength about 2.5 kgf / cm ² . Therefore, it was found that although it could not be used, it was not practically sufficient due to insufficient strength and stability.

<Ion-exchange membrane electrodialysis method> On the other hand, an ion-exchange membrane electrodialysis method can be used without using such an ion-exchange resin method. By this ion exchange membrane electrodialysis method, the SiO ₂ concentration of the present invention is 1
It is possible to obtain a dealkalized water glass solution having a weight ratio of not less than 6%, a SiO ₂ / X ₂ O (X: alkali metal) molar ratio of not less than 6 and a pH in the range of 7 to 12.

The anion exchange membrane used in the present invention is not particularly limited, and a known anion exchange membrane can be used. There is no particular limitation on the anion exchange group of the anion exchange membrane, and known anion exchange groups, for example, ammonium base, pyridinium base, primary amino group, secondary amino group,
Anion exchange groups such as tertiary amino groups can be used. Among them, an ammonium base which has basic resistance and whose exchange group is dissociated even under basicity is desirable. In addition, this anion exchange membrane can be of polymer type, condensation type, homogeneous type, non-uniform type, with or without a reinforcing core material, hydrocarbon type, fluorine type, anion exchange derived from materials and manufacturing methods. The film may be of any type, without limitation, such as type and type. The preferred anion exchange membrane of the present invention is preferably a base-resistant anion exchange membrane because of its contact with a base.

Further, the cation exchange membrane used in the present invention is not particularly limited, and a known cation exchange membrane can be used. For example, a cation exchange membrane in which sulfonic acid groups, carboxylic acid groups, and a plurality of these ion exchange groups are mixed can be used. In addition, this cation exchange membrane
Polymerization type, condensation type, uniform type, non-uniform type, with or without reinforcing core material, hydrocarbon type, fluorine type,
Any type of cation exchange membrane derived from the production method may be used without particular limitation. In view of contact with the preferred cation exchange membrane base of the present invention, a base resistant cation exchange membrane is particularly preferred.

In the present invention, the electrodes of the electrodialysis device are:
Known ones can be used without any limitation. That is, platinum, titanium / platinum, carbon, nickel, ruthenium / titanium, iridium / titanium, etc. may be used as the anode, and iron, nickel, platinum, titanium / platinum, carbon, stainless steel, etc. may be used as the cathode. Further, a known structure is employed without particular limitation for the structure of the electrode. As a general structure, a plate shape, a mesh shape, a lattice shape, and the like can be given.

In the present invention, it is preferable to use sodium hydroxide and potassium hydroxide as the electrode solution and nickel as the negative electrode.

In the present invention, the electrodialysis apparatus is constituted by alternately arranging cation exchange membranes and anion exchange membranes between electrodes to form a base chamber and a concentration chamber. FIG. 1 is an explanatory view showing a typical example of the electrodialysis apparatus of the present invention. However, the electrodialysis apparatus of the present invention is not limited to FIG. 1, and a known structure is employed without any particular limitation. The most preferable structure as an electric conduction device for obtaining the non-alkali silica sol of the present invention is that an anion exchange membrane and a cation exchange membrane are alternately provided through a chamber frame having a cutout portion at the center for forming each chamber. It is a so-called filter press type structure that is arranged and tightened from both ends. Each chamber frame is provided with a liquid supply port and a liquid discharge port, and each liquid supply port and the liquid discharge port are connected to a main pipe via a branch pipe as necessary. Generally, a spacer having a distribution function for maintaining the thickness of the chamber frame uniform and making the flow of the supplied liquid uniform is provided in the inner space of the chamber frame.

Next, the principle of the ion exchange membrane electrodialysis will be described together with the production method. When a pair of anode and cathode are set in the electrolyte solution and a direct current is applied, cations move toward the cathode and anions move toward the anode. The ion exchange membrane electrodialysis utilizes such properties of ions, and the equilibrium reaction (hydrolysis) in the diluted No. 3 water glass aqueous solution is expressed by the following equations (5) and (6). It is.

[0034]

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[0035]

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Thus, a water glass aqueous solution can be obtained using the manufacturing apparatus illustrated in FIG. That is, the anode 2 and the cathode 3 are arranged at both ends of the electrodialysis tank 1, respectively.
The anion exchange membrane A is located closest to the cathode, the cation exchange membrane K is located closest to the anode, and the cation exchange membrane K and the anion exchange membrane A are alternately located therebetween. An enrichment chamber 10 and a desalination chamber 20 are formed alternately, electricity is supplied to each of the electrodes 2 and 3, a water glass aqueous solution is passed through the desalination chamber 20, and a sodium hydroxide aqueous solution or potassium hydroxide is passed through the enrichment chamber 10. Electrodialysis is performed by flowing an aqueous solution.

In this case, when a direct current is applied between the electrodes 2 and 3, NaO, which is a strong electrolyte having a very high dissociation property, is used.
Na ions of H easily pass through the cation exchange membrane K and move to the next chamber. On the other hand, silicic acid is a weak electrolyte (K1 = 1
0 ^-9.8 and K2 = 10 ^-12 ), so that it hardly permeates through the anion exchange membrane A, so that the Na-deionizing chamber (desalting chamber 20) and the Na-ion concentrating chamber (concentrating chamber 10) are provided for each compartment. Becomes

Using this principle, it is possible to produce water glass (hereinafter referred to as dialyzed silica) in which Na ions, which are alkali components in water glass, are reduced.

(Example of the production of dialyzed silica) An example of the production of the alkali-free water glass solution of the present invention is shown by using an electrodialyzer (TS-2-10, manufactured by Tokuyama Corporation) under the apparatus conditions shown in Table 1. The SiO ₂ content was adjusted to 6% under the conditions shown in Table 2.
No. water glass (Electrical conductivity: EC = 24mS / cm)
Dialysis was performed until C = 4.5 mS / cm. The operation is performed by rinsing water for each batch (four times for 10 minutes) and then dialysis of the next batch (intermittent operation) and dialysis of the next batch without rinsing water for each batch (continuous operation) Driving).

The dialysis was performed until the electric conductivity (24 mS / cm) of the undiluted solution became 4.5 mS / cm. As a result, the current efficiency of dialysis, the rate of desalination, and the amount of electroosmotic water were as shown in Table 3. The relationship between dialysis time and conductivity and the relationship between pH and conductivity are shown in FIGS.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

During the intermittent operation, there was no trouble that the concentrated solution became cloudy. However, during the continuous operation, the flow rate of the concentrated solution was reduced in the second batch, and a clogging phenomenon occurred. As a result of disassembling the dialysis membrane, the concentration chamber was filled with gel.

Considering the cause, the dialysis rate gradually decreases from around 9 mS / cm in electric conductivity, and the phenomenon that occurs due to the difficulty of conducting electricity in water glass as desalination proceeds. Although it is considered that the inflection point where the pH of water glass starts to drop sharply near the same electrical conductivity is considered, this inflection point is Na ion which is free or weakly bonded to silicic acid. It is considered that almost the entire amount was desalted, and after this point, it is also considered that Na ions that have a strong bond with silicic acid and silicate ions that are slightly electrolyzed have begun to be desalinated.

The turbidity of the concentrated solution was determined by using Na0H prepared with pure water.
In view of the fact that no turbidity occurs when using the solution, this turbid matter reacts with silicate ions in which Ca ions contained in tap water slightly migrate from the desalination side. It is considered that calcium silicate was generated. It is also conceivable that the gel generation during continuous continuous rotation is such that Fe ions and Al ions contained in the water glass migrate to the concentration side and react with the silicic acid. Thus, an experiment was conducted on the assumption that adding a sequestering agent (chelating agent) to the concentrated solution in advance could suppress clouding and the occurrence of gel. As a result, disodium ethylenediaminetetraacetate (EDTA · 2Na · 2H
By adding 1 g / l of ₂₀ ), the generation of cloudy substances was suppressed.

Table 4 shows the results of component analysis of the obtained dialyzed silica.
It was shown to.

[0048]

[Table 4]

[0049] Dialysis silica, appearance, and it takes a little cloudy compared to dilution water glass, moving SiO ₂ concentration in the compositional water during dialysis, it is somewhat concentrated by electrolysis, Na ₂ The 0 concentration was about 1/5 desalted. In addition, despite being a high molar ratio water glass having a molar ratio of about 20, it is stable (even if left for several months,
0 No ₂ of occurrence).

FIG. 4 shows the relationship between the pH and the electrical conductivity of the dialyzed silica immediately after dialysis. From these results, the dialyzed silica was aged for about 24 hours immediately after dialysis,
It turns out that it enters a stable state.

In order to examine the structure of this dialyzed silica, N
MR (nuclear magnetic resonance) and infrared absorption spectrum (l
R) was measured. As a result of the measurement, it has a structure similar to that of a commercially available colloidal silica, and it is considered that the colloidal silica is small in molar ratio.

(Regarding Cloudiness) As described above, it is effective to use a chelating agent for sequestering to prevent cloudiness. The experimental results that lead to this will be described.

JIS No. 3 water glass was diluted with SiO ₂
As a desalting solution, a solution prepared to have a concentration of 6% was used. As shown in Table 8, (1) NaOH solution obtained by dissolving 20 g of NaOH in pure water, (2) tap water While dissolving 20 g of NaOH in water, disodium ethylenediaminetetraacetate (EDTA
Na · 2H ₂ 0) was not added, and the amount of addition was changed in four ways as shown in the same table, and electrodialysis was performed until the electric conductivity of the desalted solution became 4.5 mS / cm. During this process, the dialysis status was visually observed. Table 5 shows the results.

Here, the dialysis conditions were as follows: the desalted solution was 2.0 liters, the concentrated solution was 2.0 liters, and the flow rate circulated by the pump was 3.0 liter / min on the desalted solution side and the concentrated solution side. After completion of one batch, the desalted solution and the concentrated solution were replaced, and dialysis was performed up to two batches.

Further, the Ca ion concentration of the tap water used was 32 mg / liter, and the amount of EDTA · 2Na · 2H ₂₀ (molecular weight 372.2 g) for theoretically masking the Ca ions was about 0. 3 g / liter (=
(0.032 / 40) × 372.2).

[0056]

[Table 5]

As the observation results, those prepared with pure water,
And EDTA ・ 2Na ・ 2H to those prepared with tap water
_In the case of the concentrated liquid in which 20 was added in an amount of not less than the theoretical amount, no turbidity was generated. On the contrary, when the added amount was less than the theoretical amount, the turbidity was observed although there was a difference in the degree of opacity.

Further, the occurrence of cloudiness was observed for 1
Although the dialysis time in the batch was slightly longer, no change was observed in the pump flow rate. However, in the second batch, the pump flow rate was reduced, and those with a large degree of white turbidity were clogged and stopped flowing. This phenomenon is because the silica gel, which is the cause of cloudiness, was gradually clogged between the membranes during dialysis, and completely filled the membranes in the second batch. EDT
Those obtained by adding A · 2Na · 2H ₂ 0 and 0.1 g / liter, although turbidity is the degree to which slightly occurs, that is generating clogging gradually between film, determined from the change of the pump flow rate did it.

In addition to the experimental examples described above, as chelating agents for sequestering, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, propylenediaminetetraacetic acid, bis (2-hydroxyphenylacetic acid) ethylenediamine, Alternatively, it was confirmed that the use of a salt selected from the group consisting of these salts and two or more of these salts is also effective in preventing cloudiness.

(Use as ground improvement injection material)
The above-mentioned dialyzed silica can be suitably used as a ground improvement injection material. As a reaction material of the dialysis silica, an organic acid and / or an inorganic acid can be used, which is used for neutralizing an alkali component in water glass and making the pH acidic, and specifically, Is sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyphosphoric acid, boric acid, carbonic acid,
Baking soda and the like, and organic acids include acetic acid, tartaric acid and citric acid.

Since the water glass (dialysis silica) of the present invention has been subjected to a dealkalization treatment, it is a great feature that a non-alkali silica sol ground improvement injection material can be obtained by using a small amount of a weak acid. Since the preparation of the non-alkali silica sol ground improvement injection material using the above dealkalized water glass solution and the reaction material is possible only by adding the reaction material while stirring the dealkalized water glass solution, it is extremely simple, In addition to the stirring tank, a liquid can be prepared using a line mixer or the like. The ground improvement injection material thus prepared can be injected into the ground as an injection material of one liquid by using an appropriate injection pipe.

The soil-improved injection material obtained in the present invention has a lower concentration of acid and alkaline cations contained in the acidic silica sol as a component thereof, and therefore has a lower in-liquid than the conventional non-alkali silica sol soil-improved injection material. Since the stability of silica is high, the pH value at which a gel time similar to those is obtained is closer to the neutral region. Therefore, when used for ground improvement, the elution and mixing of acids and alkali metal salts that affect the environment can be significantly suppressed.

In addition, the excellent ground improvement effect of the conventional sodium silicate-acid non-alkali silica sol ground improvement injection material is inherited as it is.

<Experimental Examples as Ground Injection Material> Dialysis silica itself is stable and has no gel time. Therefore,
After examining the types of reactants and retarders in the non-alkali silica sol solution mainly composed of dialyzed silica, the basic characteristics were measured.

The SiO ₂ concentration of the activated silica sol was adjusted to 6%, and a reactant and a retarder were added thereto to prepare a sample. Toyoura sand was used for the strength test, the penetration test, and the measurement of the gel time.

Using a phosphoric acid, a citric acid as a reactant, and NaCl as an auxiliary, a gel time was measured with the composition shown in Table 6.

From the experimental results of the gel time shown in Table 7, since the formulation N0.5 has a gel time as the injection material for liquefaction, the results of the physical property tests performed under these blending conditions are shown below. The results of the uniaxial compression test are shown in Table 8 below.

[0068]

[Table 6]

[0069]

[Table 7]

[0070]

[Table 8]

Here, in the uniaxial compression test, the underwater curing was performed by removing and shaping the test specimen of 7 days old in wet-air mold curing and then immersing it in constant temperature (20 ° C.) tap water.

FIG. 5 shows a one-dimensional infiltration experiment, FIG. 6 shows a result of a dissolution test, and FIG. 7 shows a result of a change in volume of a homogel.

The soil gel time can be adjusted by increasing or decreasing the amount of citric acid and the pH, and it is necessary to change the composition for each type of sand. The strength was 2.6 kgf / cm ² in both the mold and the water. No deterioration due to the water was observed, and the strength was higher than the target strength. The penetration ability was large, and the strength was the same even at a position away from the injection port. The change in the volume of the homogel was within the target conditions with the occurrence of only about 0.3% shrinkage at 30 curing. S
i0 ₂ dissolution rate is about 2% curing 30 days, were comparable if ho and non alkaline silica sol. It was also found that the durability was sufficient.

Further, the water glass of No. 3 has an SiO ₂ concentration of 6
% Of those, those Si0 ₂ concentration of water glass No. 3 is 7%,
For each of the dialysed silica having a SiO ₂ concentration of 6% and the dialyzed silica having a SiO ₂ concentration of 7%,
As shown in Table 9, when phosphoric acid was used as a reaction material, the pH was adjusted to the value shown in the table, and the gel time of Toyoura sand was measured, the results shown in FIGS. 8 to 9 were obtained.

[0075]

[Table 9]

The results show that the amount of the reactant required to obtain the same gel time by using the dialyzed silica obtained by the present invention as compared with the case of using the conventional No. 3 water glass was about 1/8. This indicates that the pH range usable for injection is also closer to the neutral range than before.

The conventional No. 3 water glass having an SiO ₂ concentration of 6% (pH: 4.0, 75% phosphoric acid content: 59 l / m ³ ) and the dialyzed silica obtained by the present invention were used. When a homogel dissolution test was performed on a sample having an SiO ₂ concentration of 6% (pH: 5.2, 75% phosphoric acid amount: 7.3 liter / m ³ ), the results shown in FIG. 10 were obtained.
Each of these shows that the gel time of the injected material is about 1 hour.

In this test, a homogel was prepared with a diameter of 5 cm and a height of 1 cm.
A cylinder molded into a 0 cm column was immersed in 2 liters of pure water, and the electrical conductivity over time was measured.
The results shown in FIG. 10 show that the amount of elution is extremely small according to the compact formed using the non-alkali silica sol according to the present invention.

[0079]

As described above, according to the present invention, the amount of the reactant required to obtain the same gel time by using dialyzed silica as compared with the case of using conventional No. 3 water glass is reduced. It becomes about 1/8 or less, and p
The H region is also closer to the neutral region than in the past, and a non-alkali silica sol having little effect on the environment when used as a ground improvement material can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an example of equipment for producing a dealkalized water glass solution by the ion exchange membrane electrodialysis method of the present invention.

FIG. 2 is a graph showing experimental results.

FIG. 3 is a graph showing experimental results.

FIG. 4 is a graph showing experimental results.

FIG. 5 is a graph showing experimental results.

FIG. 6 is a graph showing experimental results.

FIG. 7 is a graph showing experimental results.

FIG. 8 is a graph showing experimental results.

FIG. 9 is a graph showing experimental results.

FIG. 10 is a graph showing experimental results.

Continued on the front page (72) Inventor Masatoshi Iio 4-2-25 Kudankita, Chiyoda-ku, Tokyo Inside Light Industry Co., Ltd. (72) Inventor Tetsuya Haneda 4-2-35, Kudankita, Chiyoda-ku, Tokyo (72) Inventor: Fumio Hanada 1-1, Mikage-cho, Tokuyama-shi, Yamaguchi Pref. Tokuyama Co., Ltd. (72) Inventor: Noriyuki 1-1, Mikage-cho, Tokuyama-shi, Yamaguchi pref. 72) Inventor Hiroshi Oketa 1-1, Mikage-cho, Tokuyama-shi, Yamaguchi F-term in Tokuyama Corporation (reference) 4H026 CA03

Claims (6)

[Claims] 1. The method according to claim 1, wherein the SiO ₂ concentration is at least 1 wt% and the SiO ₂ /
When the molar ratio of X ₂ O (X: alkali metal) is 6 or more, and p
H is in the range of 7 to 12, and the dealkalized water glass solution is characterized in that: 2. An electrodialysis of water glass using an ion-exchange membrane as a diaphragm, and a dealkalization treatment of an alkali component. The SiO ₂ concentration is 1 wt% or more, and SiO ₂ / X ₂ O is obtained.
(X: alkali metal) molar ratio is 6 or more and pH is 7
A de-alkali water glass solution, characterized by being in the range of from 12 to 12. 3. A water glass by passed through a cation exchange resin and ion exchange of alkali metal components, is obtained by de-alkali treatment, SiO ₂ concentration of 1 wt% or more, SiO ₂ / X
The molar ratio of ₂ O (X: alkali metal) is 6 or more and the pH is 2
Is in the range of 7 to 12. 4. An anode and a cathode are disposed at both ends of the electrodialysis tank, and a cation exchange membrane and an anion exchange membrane are alternately positioned therebetween, so that a concentration chamber and a desalination chamber are alternately arranged. formed, the with energizing the respective electrodes, wherein the desalting compartment is circulated water glass solution, subjected to electrodialysis by circulating aqueous sodium or potassium hydroxide solution hydroxide into the concentrating chamber, SiO ₂ concentration of 1wt % Or more, SiO ₂ / X ₂ O (Na
Alternatively, a method for producing dealkalized water glass, wherein an aqueous solution of dealkalized water glass having a molar ratio of K) of 6 or more and a pH in the range of 7 to 12 is obtained. 5. The method of claim 4, wherein said aqueous solution of sodium hydroxide or potassium hydroxide contains a chelating agent for sequestering. 6. The chelating agent for sequestering includes disodium ethylenediaminetetraacetate, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, propylenediaminetetraacetic acid, and bis (2-hydroxyphenylacetic acid). Ethylenediamine, or salts thereof, and their 2
The method for producing dealkalized water glass according to claim 5, wherein the method is selected from the group consisting of at least one kind.