JP2016187789A - Method for neutralizing alkali solution, neutralization device, water treatment method and water treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably neutralize an alkali solution discharged through a treatment of radioactive liquid waste etc., within a range of pH 3-10, without injecting chemicals.SOLUTION: Treatment-target water is sequentially passed through an alkali type titanic acid adsorbent column 1 and a hydrogen type titanic acid adsorbent column 2. When the water passes through the alkali type titanic acid adsorbent column 1, an alkaline component is eluted and the pH of the treatment water increases. However, by passing the obtained alkali solution through the hydrogen type titanic acid adsorbent column 2 in the subsequent stage, an ionic exchange occurs between an alkali metal ion and a hydrogen ion, and the alkali metal ion is absorbed and the hydrogen ion is discharged, so that the pH can be lowered.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for neutralizing an alkaline solution without injecting a chemical solution. The present invention also relates to a water treatment method and a water treatment apparatus using this neutralization technique.

When adjusting the pH of the solution to be treated, adjustment to the target pH is usually performed by pouring an acid or alkali such as hydrochloric acid or caustic soda by time-division proportional control or ON-OFF control.
Thus, when pH is adjusted by chemical injection, there is a problem that the amount of drainage is increased by the amount of chemical solution that has been injected, and a space for installing a chemical solution tank, a chemical injection device, etc. for neutralization is required.

Depending on the type of wastewater, for example, in the treatment of radioactive liquid waste, it is not preferable to increase the amount of wastewater, and no chemical injection pH adjustment is required without increasing the amount of wastewater.
For example, in the method for treating radioactive Sr-containing water using titanate described in Patent Documents 1 and 2, pH adjustment is required as follows, but this pH adjustment is desired to be performed without chemical injection. .

That is, the removal of radioactive Sr by ion exchange using alkali metal titanate as described in Patent Documents 1 and 2 shows a simple and high removal effect, but potassium and sodium from titanate, etc. Since the alkali component is eluted by ion exchange between the alkali metal ions and Sr ions, the treated water is generally alkaline with a pH of 10 to 13. This treated water may need to be neutralized in the neutral zone for the purpose of improving the handling of the subsequent process and storage, but in this case, the amount of radioactive liquid waste is neutralized by chemical injection. Therefore, a technique for neutralizing the alkaline liquid without increasing the amount of waste liquid is required.
Moreover, it is preferable that the process of the radioactive liquid waste treatment is simple, and it is advantageous in terms of operation management that control equipment such as chemical injection equipment can be simplified as non-chemical injection. From this point of view, neutralization without chemical injection is desired.

  In addition, as a method of adjusting the pH without chemical injection, a method using an H-type cation exchange resin is known. However, in pH adjustment using an H-type cation exchange resin, as shown in Comparative Example 1 described later. The pH is greatly reduced, and it is difficult to adjust the pH to a neutral range.

JP 2013-246145 A Japanese Patent No. 4428541

  The present invention relates to a method and apparatus for stably neutralizing an alkaline liquid discharged in the treatment of radioactive waste liquid or the like into a pH range of 3 to 10 without injecting a chemical solution, and a water treatment method and a water treatment using this technique. It is an object to provide an apparatus.

As a result of intensive studies to solve the above problems, the present inventor has found that the pH can be stably adjusted to a neutral range of pH 3 to 10 by using a hydrogen-type titanate adsorbent.
The present invention has been achieved based on such findings, and the gist thereof is as follows.

[1] A method for neutralizing an alkaline liquid, comprising contacting the alkaline liquid with a hydrogen titanate adsorbent.

[2] The method for neutralizing an alkaline liquid according to [1], wherein the alkaline liquid is obtained by bringing water to be treated into contact with an alkaline titanate adsorbent.

[3] In [1] or [2], the hydrogen-type titanic acid adsorbent contains hydrogen-type titanic acid obtained by replacing the potassium atom of potassium dititanate with a hydrogen atom. Liquid neutralization method.

[4] The method for neutralizing an alkaline liquid according to any one of [1] to [3], wherein the alkaline liquid is neutralized in a pH range of 3 to 10.

[5] A water treatment method comprising contacting water to be treated with an alkaline titanate adsorbent and then contacting with a hydrogen titanate adsorbent.

[6] The water according to [5], wherein water to be treated is passed through an adsorption layer filled with an alkali-type titanate adsorbent and then passed through an adsorption layer filled with a hydrogen-type titanate adsorbent. Processing method.

[7] An alkali liquid neutralizing apparatus having an adsorption vessel or adsorption tower filled with a hydrogen-type titanate adsorbent.

[8] In [7], the hydrogen-type titanic acid adsorbent contains hydrogen-type titanic acid obtained by substituting the potassium atom of potassium dititanate with a hydrogen atom. .

[9] An adsorption vessel or adsorption tower filled with an alkaline titanate adsorbent and an adsorption vessel or adsorption tower filled with a hydrogen titanate adsorbent, and water to be treated are passed in series in this order. A water treatment apparatus.

[10] The hydrogen-type titanium obtained in [9], wherein the alkali-type titanate adsorbent contains potassium dititanate, and the hydrogen-type titanate adsorbent replaces the potassium atom of potassium dititanate with a hydrogen atom. A method for neutralizing an alkaline solution comprising an acid.

[11] The water treatment apparatus according to [9] or [10], wherein the adsorption vessel or the adsorption tower has a cylindrical shape.

[12] The water treatment apparatus according to [11], wherein a height / diameter ratio of the packed bed of the adsorbent formed in the cylindrical adsorption vessel or adsorption tower is 1 to 10.

[13] The water treatment apparatus according to any one of [9] to [12], wherein a perforated plate is provided in an upper part and / or a lower part in the adsorption vessel or the adsorption tower.

[14] The water treatment device according to [13], wherein the perforated plate has a lattice-like or slit-like structure.

[15] The water treatment device according to [15], wherein the perforated plate has a lattice interval or a narrow gap interval of 0.1 to 0.5 mm.

[16] A water treatment method comprising passing water to be treated through the water treatment apparatus according to any one of [9] to [15].

According to the present invention, the alkaline liquid can be stably neutralized to a desired pH in the range of pH 3 to 10 without injecting the chemical liquid and therefore without increasing the amount of waste liquid.
ADVANTAGE OF THE INVENTION According to this invention, the chemical injection equipment and chemical injection control required when neutralizing using a chemical | medical solution become unnecessary, and simplification of a process can be aimed at.

It is a systematic diagram which shows an example of embodiment of the water treatment apparatus of this invention. It is a graph which shows the result of the reference example 1, the comparative example 1, and Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

<Mechanism>
When an alkaline liquid is brought into contact with a hydrogen titanate adsorbent, ion exchange occurs between the alkali metal ions in the liquid and the hydrogen ions of the hydrogen titanate adsorbent, and the alkali metal ions are adsorbed on the hydrogen titanate adsorbent. Instead, the pH can be lowered by releasing hydrogen ions from the hydrogen-type titanate adsorbent.
If the alkaline solution is made alkaline by the treatment with the alkaline titanate adsorbent, the alkaline component is eluted from the alkaline titanate adsorbent and the pH of the treated water is increased by the treatment with the alkaline titanate adsorbent. However, after that, contact with a hydrogen titanate adsorbent causes ion exchange between alkali metal ions and hydrogen ions, and alkali metal ions are adsorbed and hydrogen ions are released, so that the pH can be lowered. it can.

In the present invention, “neutralization” means broad neutralization to lower the pH of the alkaline solution, and the pH of the treated water obtained by the neutralization treatment according to the present invention is generally in the range of pH 3-10. It is appropriately determined depending on the use of the neutralized water (the type of treatment subsequent to the neutralization treatment).
For example, when anion exchange treatment is performed in the latter stage, it is preferable that the pH is lower, and in general, neutralization is performed to about pH 3 to 7. In addition, when discharging neutralized treated water to public water areas, it is necessary to comply with the drainage standards stipulated in the Water Pollution Control Law, and these standards are pH 5.8 to 8.6 outside the sea area, and pH 5.0 to 8.6 in the sea area. Since it is 9.0, it is necessary to neutralize to such a pH value.

<Alkaline solution>
In the present invention, the alkali liquid to be subjected to the neutralization treatment preferably contains an alkali metal ion that is ion-exchanged with hydrogen ions. In particular, the neutralization treatment according to the present invention is performed using an alkaline titanate adsorbent. It is suitable for neutralizing an alkaline solution containing alkali metal ions and having become alkaline with a pH of about 10 to 13 in the treatment.

  Hereinafter, the neutralization method and neutralization apparatus of the present invention will be described by exemplifying the case where it is applied to neutralization of an alkaline liquid obtained by treatment with an alkaline titanate adsorbent. The alkaline solution to be treated is not limited to those obtained by treatment with an alkaline titanate adsorbent.

<Alkali type titanate adsorbent>
Examples of the alkali type titanate adsorbent include potassium dititanate (K ₂ Ti ₂ O ₅ ), potassium tetratitanate (K ₂ Ti ₄ O ₉ ), and sodium trititanate (Na ₂ Ti ₃ O) having ion exchange ability. ₇ ) etc. are preferable, and it is preferable that the average particle diameter is 1-150 micrometers.
Further, from the viewpoint of handleability, the alkali type titanate adsorbent is preferably obtained by molding the above alkali metal titanate salt into a particle size range of 150 to 3000 μm using a binder.

Examples of the binder include clay minerals such as bentonite, attapulgite, sepiolite, allophane, halloysite, imogolite, kaolinite; sodium silicate, calcium silicate, magnesium silicate, sodium metasilicate, calcium metasilicate, magnesium metasilicate, metasilicate Examples thereof include silicate compounds such as sodium acid aluminate, calcium aluminate metasilicate, and magnesium aluminate metasilicate. These may be used individually by 1 type, and may mix and use 2 or more types.
Among these, as the binder, it is preferable to use a natural clay mineral rather than a chemical silicate compound because it can be produced at a low cost, and among the clay minerals, the mechanical strength of the granular material is also preferred. It is preferable to use fibrous clay minerals such as attapulgite and sepiolite.

  Moreover, it is preferable to add the plasticizer which gives the plasticity required for granulation similarly at the time of shaping | molding. Examples of the plasticizer include starch, corn starch, molasses, lactose, cellulose, cellulose derivatives, gelatin, dextrin, gum arabic, alginic acid, polyacrylic acid, glycerin, polyethylene glycol, polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP). , Water, methanol, ethanol and the like. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  After mixing the alkali metal titanate, binder, and plasticizer at a predetermined mixing ratio, granulated and dried, and then fired, the mechanical strength is improved and vibration and impact applied during transportation, etc. It is possible to suppress crushing due to the like, and dropping of primary particles when thrown into water.

  The usage-amount of a binder is not specifically limited, It is preferable that it is 0.1-0.5 mass part with respect to 1 mass part of alkali metal titanate powder. When the amount of the binder used is too small, the strength of the obtained granular material is weak, and there is a possibility that the primary particles may fall off when crushed by vibrations or impacts applied during transportation or the like, or when poured into water. When the amount of the binder used is too large, the proportion of the alkali metal titanate that is the active site for cation exchange becomes small, so that the cation exchange capacity (radioactive material adsorption amount) becomes small.

  The usage-amount of a plasticizer is not specifically limited, It is preferable that it is 0.01-0.1 mass part with respect to 1 mass part of alkali metal titanate powder. If the amount of the plasticizer used is within the above range, the alkali metal titanate powder can be effectively molded.

  In consideration of the production cost, the plasticizer used is preferably water, and further has a property of thickening when it comes into contact with water, and the substance that contributes to the bonding of the particles by its thickening action and water. It is preferable to use together. Considering this point, it is preferable to use water and a cellulose derivative, PVA or the like in combination as a plasticizer.

  When water and a cellulose derivative and / or PVA are used in combination as a plasticizer, the blending ratio (mass basis) of water and the cellulose derivative and / or PVA in the binder is preferably 1000: 1 to 10: 1. If the blending ratio is within this range, the alkali metal titanate powder can be effectively molded.

  As a method of forming an alkali metal titanate powder using a binder and a plasticizer, for example, an alkali metal titanate powder and a binder such as attapulgite are mixed, and water, which is a plasticizer, and a cellulose derivative are mixed. A method of granulating while adding the viscous fluid added to the mixed powder of alkali metal titanate and attapulgite, a binder such as attapulgite and a plasticizer such as cellulose are mixed with powder of alkali metal titanate and water A method of granulating and forming while adding a liquid such as the above.

  Specifically, as this granulation molding method, a rolling granulation method using a drum granulator, a dish granulator or the like; a mixed stirring granulation method using a flexo-mix, a vertical granulator or the like; Extrusion granulation method using screw type extrusion granulator, roll type extrusion granulator, blade type extrusion granulator, self-molding type extrusion granulator; tablet type granulator, briquette type granulator, etc. Compressive granulation method using a fluidized bed that granulates by spraying a binder such as water or alcohol while keeping the alkali metal titanate powder and binder suspended and suspended in the fluid to be blown up (mainly air) Although a granulation method etc. are mentioned, when considering shape | molding to a granule, a rolling granulation method or a mixing stirring granulation method is preferable.

The particle size of the alkali metal titanate thus obtained is usually 150 to 3000 μm, preferably 300 to 2000 μm, more preferably 500 to 2000 μm. When the particle size of the granular material is larger than the above range, the surface area becomes small, so that the adsorbing ability is lowered, and when it is small, there is a risk of leakage from a perforated plate of an adsorption vessel or an adsorption tower described later.
Here, the particle size of the granular material corresponds to the diameter if the granular material is spherical, and in the case of other shapes, when the granular material is sandwiched between two parallel plates, This refers to the length of the part where the distance is the largest (the distance between the two plates).

  The molded alkali metal titanate salt is preferably fired at 500 to 900 ° C. in an air atmosphere. By this firing, the binder powder and the alkali metal titanate powder are sintered, and the particle strength is improved. To do. In this calcination treatment, if the calcination temperature is less than 500 ° C., the unsintered portion remains and the particle strength becomes weak, and if it exceeds 900 ° C., the structure of the alkali metal titanate crystal is affected and the adsorption performance is reduced. It will decline.

  The firing time varies depending on the firing temperature and the size of the granular material, but is usually about 0.5 to 10 hours.

<Hydrogen titanate adsorbent>
The hydrogen-type titanic acid contained in the hydrogen-type titanate adsorbent can be obtained by replacing the alkali metal atom contained in the aforementioned alkali-type titanic acid (alkali titanate alkali metal salt) with a hydrogen atom. Specifically, alkali metal titanates such as potassium dititanate (K ₂ Ti ₂ O ₅ ), potassium tetratitanate (K ₂ Ti ₄ O ₉ ), and sodium trititanate (Na ₂ Ti ₃ O ₇ ). In addition, it can be obtained by ion exchange of alkali metal atoms such as potassium and sodium with hydrogen atoms by contacting with an acid aqueous solution such as hydrochloric acid, nitric acid and sulfuric acid. The alkali metal titanate used at this time is not particularly limited, but potassium dititanate (K ₂ Ti ₂ O ₅ ) is suitable. Potassium dititanate is preferred because it has a higher amount of alkali metal in the titanate molecule than potassium tetratitanate or sodium trititanate, and therefore has a high stoichiometric ion exchange capacity and can hold many hydrogen ions.

  The method of bringing the alkali metal titanate such as potassium dititanate into contact with the aqueous acid solution may be a batch method or a flow method, but the column is filled with an alkali metal titanate such as potassium dititanate and the aqueous acid solution is passed through. The distribution method is preferred. When ion exchange of alkali metal ions and hydrogen ions is performed by a batch method, a plurality of treatments are required, and the hydrogen ion replacement step becomes complicated. The acid used for this substitution step is not particularly limited, but strong acids such as hydrochloric acid, nitric acid and sulfuric acid are preferred. When weak acid such as acetic acid or organic acid remains, it may affect a subsequent process or the whole process, such as forming a complex with a specific component or increasing the amount of treated water TOC.

In the present invention, the hydrogen titanate adsorbent is preferably converted from the hydrogen titanate adsorbent preferably used as the alkali titanate adsorbent.
More specifically, the treatment for conversion to the hydrogen type is performed by filling the column with the above-described alkaline titanic acid adsorbent and supplying an acid aqueous solution of about 0.01 to 1 mol / L with a space velocity (SV). A method of passing water at 5 to 200 / hr is preferable. In this case, the conversion to the hydrogen type is completed by passing the aqueous acid solution until the pH of the column outlet water is 3 or less, for example, about 1-2.

<Water treatment device>
In the following, referring to FIG. 1, the water treatment apparatus of the present invention for neutralizing an alkali liquid obtained by treating water to be treated with an alkali type titanate adsorbent with a hydrogen type titanate adsorbent. Will be described.

FIG. 1 is a system diagram showing an example of an embodiment of a water treatment apparatus of the present invention.
In FIG. 1, 1 is an alkali type titanate adsorbent column packed with an alkali type titanate adsorbent 1A, and 2 is a hydrogen type titanate adsorbent column packed with a hydrogen type titanate adsorbent 2A. Water is sequentially passed through the alkali type titanate adsorbent column 1 and the hydrogen type titanate adsorbent column 2. An adsorption tower may be used instead of the column (cylindrical container).

  In the water treatment apparatus of FIG. 1, the water to be treated is passed through the alkaline titanate adsorbent column 1 and alkaline earth metal ions such as strontium in the treated water are passed through the alkaline titanate adsorbent 1A such as potassium or sodium. The resulting alkaline effluent water is passed through the hydrogen titanate adsorbent column 2 and the pH is lowered by ion exchange with the hydrogen titanate adsorbent 2A.

  There is no particular limitation on the water flow rate of the water to be treated to the alkali type titanate adsorbent column 1 and the hydrogen type titanate adsorbent column 2, but the space velocity (S. V.) is preferably 5 to 30 / hr.

  Adsorption treatment using an adsorbent is performed by filling a cylindrical container called an adsorption tower or column with the adsorbent, and passing water to be treated into the cylindrical container, and the target substance to be removed is packed in the column. Treated water that is adsorbed by the adsorbent and from which the removal target substance is removed is obtained from the column outlet. Water flowing from the upper part to the lower part of the column is called downward flowing water, and passing water from the lower part of the column to the upper part is called upward flowing water. In general, as shown in FIG. 1, water is often passed in a downward flow, but the present invention can be applied to both an upward flow and a downward flow.

  The shape of the adsorption vessel or adsorption tower used in the present invention is preferably cylindrical. If it is cylindrical, there will be no stay area | region of a water flow when water flows, and the effective utilization factor of adsorption agent can be improved.

Moreover, it is preferable that the height / diameter ratio of the packed bed of the adsorbent packed in the cylindrical adsorption container or the adsorption tower is 1-10. That is, in the method of filling a cylindrical container with an adsorbent and passing the adsorption / removal target liquid, the cylindrical container corresponds to an extrusion flow reactor in the chemical engineering field. In the extrusion flow reactor, an adsorption distribution that spreads in the flow direction, called an adsorption zone (mass transfer zone), is formed in the packed bed depending on the adsorption speed of the adsorbent and the substance to be removed, the adsorption capacity, the flow velocity of the fluid, and the like. The adsorption zone gradually expands from the inlet direction of the reactor to the outlet direction along with water flow, and when the adsorption zone eventually reaches the outlet of the reactor, the substance to be removed starts to leak. This is called breakthrough. Therefore, the length (height) of the packed bed of adsorbent formed in the cylindrical adsorption vessel or adsorption tower must be at least longer than the adsorption zone, and in order to increase the time until breakthrough, the cylindrical adsorption The higher the height of the packed bed of the adsorbent in the container or adsorption tower, the better. However, if it is too high, the reinforcement cost for preventing overturning will increase, so if you want to ensure the height, connect multiple cylindrical adsorption vessels or adsorption towers in series and design to ensure the height It is common.
For this reason, the height / diameter ratio of the packed bed of adsorbent in the cylindrical adsorption vessel or adsorption tower of the present invention has an appropriate range, and this height / diameter ratio is 1-10, especially 2-2. 5 is preferred.

Moreover, it is preferable that the adsorption container or adsorption tower used by this invention has a porous plate corresponded to a water sprinkler or a water collector. In FIG. 1, upper porous plates 11 and 21 on the inlet side of columns 1 and 2 correspond to a sprinkler, and lower porous plates 12 and 22 on the outlet side correspond to a water collector, and a packed bed of adsorbent. Is formed between them.
The water sprinkler has a role of rectifying the incoming water into a uniform flow, and the water collector has a role of preventing the adsorbent from leaking out of the adsorption vessel or the adsorption tower.

  The perforated plate as the watering device or the water collecting device preferably has a lattice-like or slit-like (slit-like) structure. When the sprinkler has a lattice-like or slit-like structure, resistance in the flow direction is generated and a rectifying action works. Further, the adsorbent can be captured by making the water collector into a lattice-like or slit-like structure, and the adsorbent can be prevented from leaking out from the adsorption vessel or the adsorption tower.

  Moreover, it is preferable that the lattice space | interval or slit (slit) space | interval of the porous plate as a water sprinkler or a water collector is 0.1-0.5 mm. If the grid spacing or narrow gap of the sprinkler is large, the fluid resistance will be small and the rectification effect will be small. If the grid spacing or narrow gap is small, the fluid resistance will be large and the pressure loss during water flow will increase. The load of power increases. On the other hand, if the grid interval or narrow gap of the water collector is large, the adsorbent leaks, and if the grid gap or narrow gap is small, the resistance of the fluid is large and the pressure loss during water flow increases and the pump power The load of increases.

  The average particle diameter of the adsorbent to be filled is often in the range of 0.5 to 2.0 mm. Therefore, the lattice interval or the fine gap interval is preferably 0.5 mm or less. Further, as described above, if the grid interval or the narrow gap is small, the pressure loss at the time of water flow increases, so the grid gap or the narrow gap is preferably 0.1 mm or more, particularly preferably in the range of 0.15 to 0.3 mm. .

  Such water treatment of the present invention is effective for the treatment of radioactive liquid waste such as seawater containing radioactive strontium as described in Patent Document 1, but is not limited to this, and low water generated in a nuclear fuel reprocessing plant. It can be suitably used for the treatment of level radioactive liquid waste.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  In the following, the preparation of the hydrogen-type titanate adsorbent and the water flow test are both cylindrical and cylindrical with an inner diameter of 14.8 mm each having a perforated plate with a lattice spacing of 0.25 mm as a water sprinkler and a water collector. A glass column (hereinafter simply referred to as “cylindrical glass column”) was used as downward flowing water.

[Preparation Example 1: Preparation of hydrogen-type titanate adsorbent]
A cylindrical glass column was packed with a potassium dititanate adsorbent (particle size: 300 to 1180 μm) synthesized in the same manner as in Example 1 of Patent Document 1 at a layer height of 100 mm, and 0.1 mol was added to the adsorbent-filled column. / L hydrochloric acid aqueous solution was passed at a space velocity (SV) of 10 / hr. The outlet water was sampled at regular intervals, water was passed until the pH reached 1, and potassium ions and hydrogen ions were substituted to prepare a hydrogen-type titanate adsorbent.

[Reference Example 1: Blank test]
A cylindrical glass column was packed with a potassium dititanate adsorbent (particle size: 300 to 1180 μm) synthesized in the same manner as in Example 1 of Patent Document 1 at a layer height of 100 mm, and this adsorbent packed column was 1/5. Diluted seawater was passed at a space velocity (SV) of 10 / hr. Artificial seawater (Marine Art SF-1, manufactured by Tomita Pharmaceutical) was used as the seawater.

FIG. 2 shows the results of sampling the outlet water at regular intervals and plotting the volume ratio (BV) of the water flow rate to the adsorbent filling volume and the pH.
As can be seen from FIG. 2, pH 12.9 and alkalinity are exhibited at the initial stage of water flow, and the pH decreases linearly with water flow. V. The pH was 11.7 and the alkalinity was high.

[Comparative Example 1]
A cylindrical glass column was packed with a potassium dititanate adsorbent (particle size: 300 to 1180 μm) synthesized in the same manner as in Example 1 of Patent Document 1 at a layer height of 100 mm (this adsorbent-filled column was referred to as “column 1 "). A cylindrical glass column was packed with an H-type cation exchange resin (DOWEX MONOSSPHERE 650C (H), manufactured by Dow Chemical Co., Ltd.) at a layer height of 100 mm (this cation exchange resin packed column is referred to as “column 2”). ). Column 1 and column 2 were connected in series, and 1/5 diluted seawater was passed under the same conditions as in the blank test of Reference Example 1.

FIG. 2 shows the results of sampling the outlet water of the column 2 at regular intervals and plotting the volume ratio (BV) of the water flow rate to the adsorbent filling volume and the pH.
As can be seen from FIG. 2, in this comparative example, the pH greatly decreased immediately after water flow, and 10B. V. PH 1.1 and strong acidity were exhibited.
Since the cation exchange resin has a high ion exchange rate, it is considered that the high concentration cation component derived from seawater and the hydrogen ion rapidly exchanged ions, and the pH was greatly lowered due to the high cation concentration.

[Example 1]
A cylindrical glass column was packed with a potassium dititanate adsorbent (particle size: 300 to 1180 μm) synthesized in the same manner as in Example 1 of Patent Document 1 at a layer height of 100 mm (this adsorbent-filled column was referred to as “column 1 "). A cylindrical glass column was filled with the hydrogen titanate adsorbent prepared in Preparation Example 1 with a layer height of 100 mm (this adsorbent-filled column is referred to as “column 3”). Column 1 and column 3 were connected in series, and 1/5 diluted seawater was passed under the same conditions as in the blank test of Reference Example 1.

FIG. 2 shows the results of sampling the outlet water of the column 3 at regular intervals and plotting the volume ratio (BV) of the water flow rate to the adsorbent filling volume and the pH.
As can be seen from FIG. 2, in this example, although the pH was as low as 3.6 immediately after passing water, the pH gradually increased to 40B. V. At pH 9.1, and thereafter a stable pH was maintained. Hydrogen-type titanic acid has a slower ion exchange rate with cations of seawater components than cation exchange resin, and it has been considered that hydrogen-type titanic acid could be stably held at pH 3 to 10 because of its action of releasing hydrogen ions.

DESCRIPTION OF SYMBOLS 1 Alkaline type titanate adsorbent column 1A Alkali type titanate adsorbent 2 Hydrogen type titanate adsorbent column 2A Hydrogen type titanate adsorbent 11, 12, 21, 22 Perforated plate

Claims (16)

  A method for neutralizing an alkaline liquid, comprising contacting the alkaline liquid with a hydrogen titanate adsorbent.   The method for neutralizing an alkaline liquid according to claim 1, wherein the alkaline liquid is obtained by bringing the water to be treated into contact with an alkaline titanate adsorbent.   3. The method for neutralizing an alkaline liquid according to claim 1, wherein the hydrogen-type titanate adsorbent contains hydrogen-type titanate obtained by substituting potassium atoms of potassium dititanate with hydrogen atoms. .   4. The method for neutralizing an alkaline liquid according to claim 1, wherein the alkaline liquid is neutralized in a pH range of 3 to 10. 5.   A water treatment method comprising contacting water to be treated with an alkaline titanate adsorbent and then contacting with a hydrogen titanate adsorbent.   6. The water treatment method according to claim 5, wherein water to be treated is passed through an adsorption layer filled with an alkali-type titanate adsorbent and then passed through an adsorption layer filled with a hydrogen-type titanate adsorbent.   An alkaline liquid neutralizing device having an adsorption vessel or adsorption tower filled with a hydrogen-type titanate adsorbent.   8. The alkaline liquid neutralizing apparatus according to claim 7, wherein the hydrogen type titanate adsorbent contains hydrogen type titanate obtained by substituting a hydrogen atom for a potassium atom of potassium dititanate.   It has an adsorption vessel or adsorption tower filled with an alkali-type titanic acid adsorbent and an adsorption vessel or adsorption tower filled with a hydrogen-type titanic acid adsorbent, and the treated water is passed in series in this order. A water treatment device characterized.   In Claim 9, the said alkaline type titanate adsorbent contains potassium dititanate, and the said hydrogen type titanate adsorbent contains the hydrogen type titanic acid obtained by substituting the potassium atom of potassium dititanate for the hydrogen atom. A method for neutralizing an alkaline solution.   The water treatment apparatus according to claim 9 or 10, wherein the adsorption vessel or adsorption tower has a cylindrical shape.   The water treatment apparatus according to claim 11, wherein a height / diameter ratio of the packed bed of the adsorbent formed in the cylindrical adsorption vessel or adsorption tower is 1 to 10.   The water treatment apparatus according to any one of claims 9 to 12, further comprising a perforated plate in an upper part and / or a lower part in the adsorption container or the adsorption tower.   The water treatment apparatus according to claim 13, wherein the perforated plate has a lattice shape or a slit-like structure.   The water treatment apparatus according to claim 15, wherein a lattice interval or a narrow gap interval of the porous plate is 0.1 to 0.5 mm.   A water treatment method, wherein water to be treated is passed through the water treatment device according to any one of claims 9 to 15.

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