JPS58174241A - Method for regenerating boron selective ion exchange resin - Google Patents

Abstract

PURPOSE:To increase stepwise the concn. of boron by adding a fresh concd. regenerating liquid to an intermediate desorbing liquid and using the same cyclically as the regenerating liquid in obtaining the desorbing liquid of boron by passing the regenerating liquid and force out water through the boron selective ion exchange resin on which boron is adsorbed. CONSTITUTION:In the stage of a passing regenerating liquid through a boron selective ion exchange resin 2 on which boron is adsorbed, passing force out water there through to obtain the desorbing liquid of boron, the desorbing liquid is divided to initial desorbing liquid A contg. boron in a low rate, intermediate desorbing liquid B contg. boron in a high rate, and late desorbing liquid C contg. boron in a low rate. The liquid A and the liquid C are removed to the outside of the system, and a fresh regenerating liquid D is added to the liquid B and is cyclically used again as the regenerating liquid. The total amt. of the liquid between the liquid A and the liquid B and the total amt. of the liquid between the liquid D and the force out water are made equal, whereby the concn. of boron of the liquid B is increased gradually. As a result, the heat energy required for the prior art is reduced considerably.

Description

[Detailed description of the invention] It is about the method.

When removing relatively small amounts of boron from water with a high salt concentration, such as seawater or wastewater, precipitation methods and general ion exchange methods are ineffective, and boron-selective ion exchange resins are usually used. is used.

The boron-selective ion-exchange resin is made by chloromethylating a base material copolymerized with styrene divinylbenzene, and then bonding a polyhydric alcohol compound such as N-methyl-glucamine, and its basic structure is as follows. It can be expressed as follows.

-CH-CH3-CH-CH2-CH-CH2-CH2
-CH-CH2-CI(2 1 (HCI) ・N -C6Ho(OH)5(Hcl)
-N-C6H3(OH),.

1 CH3CH3 Boron in water normally exists as borate ions, but borate ions have the property of reacting with polyhydric alcohol compounds such as mannitol to form strong acids.

The boron-selective ion exchange resin utilizes the above-described reaction between boric acid ions and polyhydric alcohol compounds, and N-methyl-glucamine forming an exchange group.
Boron is adsorbed by reacting e with boric acid ions. In addition, since the reaction proceeds selectively,
It is possible to selectively remove small amounts of boron from water such as seawater, which has an extremely high concentration of coexisting salts.

Amberlite (registered trademark) RA-743 is used as such a boron-selective ion exchange resin.

The method for using the boron-selective ion-exchange resin is to fill a column with the resin in the same way as a normal ion-exchange resin, and to pass boron-containing water through the packed bed, or to pour the resin into boron-containing water. Boron is adsorbed by adding it and causing a patch reaction.

Further, boron can be desorbed by contacting the resin on which boron has been adsorbed with a mineral acid such as sulfuric acid or hydrochloric acid or an alkali such as hydrochloric acid as a regenerating liquid.

By the way, boron-selective ion exchange resins have the advantage of being able to selectively adsorb small amounts of boron from waters with high salt concentrations such as seawater and wastewater, but on the other hand, the amount of boron adsorbed is quite small compared to ordinary ion exchange resins. However, the drawback is that the boron concentration of the desorption solution is very low. Therefore, when concentrating the desorption liquid to recover boron as a solid substance, extra thermal energy is required.

Generally speaking, if you want to obtain a thick desorption solution, you do not collect the first half or the second half of the desorption solution, but only take out the middle dark part. If the concentration of the desorption solution is insufficient, satisfactory results cannot be obtained.

The present invention has been made in view of this point.

The present invention provides a regeneration method capable of obtaining a boron desorption solution with a relatively high concentration.

That is, in the present invention, when a regeneration solution is passed through a boron-selective ion exchange resin that has adsorbed boron, and then extruded water is passed through to obtain a boron desorption solution, the desorption solution is used as an initial desorption solution with a low boron content. Solution A and medium-term desorption solution B with high boron content
The initial desorption liquid A and the late desorption liquid C have a low boron content, and the initial desorption liquid A and the late desorption liquid C are taken out of the system, and a new concentrated regenerated QD is added to the middle desorption liquid B, and the regenerated liquid is regenerated again. The boron concentration of the desorption liquid B is gradually increased by making the total liquid volume of the initial desorption amount A and the late desorption liquid C equal to the total liquid volume of the concentrated regeneration fi, D and the extruded water. This is a method for regenerating a boron-selective ion exchange resin.

The present invention will be explained in detail below.

The present invention is based on the knowledge that the purity of the regenerating liquid does not matter much with respect to the desorption of boron from a boron-selective ion exchange resin, and that the concentration of acid or alkali in the regenerating liquid is the dominant factor.

In other words, the present invention basically involves adding a new regeneration solution to the boron-containing desorption solution obtained in the previous cycle, using this again as the regeneration solution, and repeating this operation sequentially to reduce the boron concentration of the desorption solution. This is a step-by-step increase in

However, the problem here is the newly added regeneration liquid,
The amount of desorption fluid gradually increases as the extruded water passes through it.

That is, even if the amount of boron in the desorption solution is increased by the basic operation as described above, an increase in the boron concentration cannot be expected unless the amount of the solution increases in proportion to the amount of boron.

The present invention solves this problem by removing the initial desorption liquid and the latter desorption liquid from the system, and introducing new regeneration liquid and extrusion water into the system in an amount corresponding to the amount of the removed liquid.

This will be explained in more detail using FIG. 1, which shows the liquid balance of the regeneration system.

In Fig. 1, 1 is a resin tower filled with a boron-selective ion exchange resin 2, and the raw water 3 containing boron is passed through the resin tower 1 using a conventional method, and the treated water 4 is drained out of the system. After boron is adsorbed onto the ion exchange resin 2, the following regeneration is performed.

That is, a regenerating liquid B' such as sulfuric acid, hydrochloric acid, or sodium hydroxide is passed through the tube, and then extruded water E is passed through the tube.

Through such operations, a boron desorption solution can be obtained with a desorption curve as shown in FIG.

In the present invention, the desorption liquid is divided into an initial desorption liquid A having a low boron content, a middle desorption liquid B having a high boron content, and a late desorption liquid C having a low boron content. Then, the initial desorption liquid A and the late desorption liquid C are taken out of the system, and a new concentrated regeneration liquid is added to the intermediate desorption liquid B to be used as the regeneration liquid B' in the next regeneration.

As shown in the figure, the amount of liquid taken out of the regeneration system is only the initial desorption liquid A and the late desorption liquid Qc, and the amount of liquid e that enters the system is only extruded water E and concentrated regeneration liquid. .

Therefore, by repeating this regeneration operation while maintaining the liquid balance so that the relationship A + C = E is satisfied, the amount of medium-term desorption liquid B is always constant, and the amount of boron in the desorption liquid increases with each cycle. Concentrations can be increased sequentially.

Note that since the initial desorption liquid A and the latter desorption liquid C discharged to the outside of the system contain a small amount of boron, it is preferable that the two desorption liquids flow into a raw water tank or the like and mix with the raw water. Note that even if the salt concentration of the raw raw water increases slightly due to the mixing, there is no problem with regard to boron adsorption.

The regenerating liquid used in the present invention is sulfuric acid or hydrochloric acid.

Mineral acids such as nitric acid and hydroalkali such as hydrocarbon soda can be used, but mineral acids are superior to hydroalkali in terms of desorption effect. Among mineral acids, sulfuric acid is preferable because it does not emit corrosive vapors during the subsequent concentration operation.

When using sulfuric acid as the regenerating liquid, its concentration is 5 to 10%.
is appropriate, and it is preferable to use a concentrated regenerating liquid with a concentration of 30% or more.

It should be noted that it is possible to reduce the amount of boron leaked in two passes of water by regenerating the ion exchange resin with a mineral acid such as sulfuric acid, and then treating the ion exchange resin again with sodium chloride or aqueous ammonia, so the boron concentration in the treated water can be reduced. If this is a problem, it is better to perform two-stage regeneration using acid and alkali.

In the present invention, the amounts of initial desorption liquid A, middle desorption liquid B, late desorption e and c, concentrated regeneration liquid, and extruded water E can be arbitrarily determined, but basically A + C = E + D. It is preferable to use KL so that at least 70 parts or more of the total boron desorbed from the ion exchange resin is contained in the medium-term desorption liquid B.

By repeating the regeneration as explained above, the boron concentration in the medium-term desorption solution B increases step by step, but at a certain point it reaches the saturated dissolved concentration of boron, and even then, if the regeneration operation is repeated, the concentration of boron in the ion exchange resin increases. The desorption effect decreases. Therefore, the intermediate desorption solution B is taken out of the system at an appropriate time before the saturated dissolved concentration is reached, and the following operation is performed.

The main components of the intermediate desorption liquid B are sulfuric acid and boric acid when sulfuric acid is used as the regenerating liquid. Therefore, boric acid can be precipitated as a solid by heating the medium-term desorption liquid B at normal pressure or at reduced IF to evaporate water.

In this way, boric acid is separated as a solid, and the residual liquid obtained at the same time contains some impurities such as boron, but most of it is concentrated sulfuric acid. Therefore, the residual liquid may be reused as a concentrated regeneration liquid in the above-mentioned regeneration process.

As described above, according to the present invention, a desorption liquid with a high boron concentration can be obtained, so that the thermal energy required conventionally can be greatly reduced.

The present invention will be explained in detail below.

Example 500 ml of Amberlite IRA-743 was packed in a column, and the raw water shown in Table 1 was passed through the column at 5 VIO of 4.8 to adsorb boron.

Then 104 H2SO, zz5ml (98chi H2S
23.5 f/lR) was passed through an SV4 and then extruded using an extrusion water of 500 mA' using an SV4, and a desorption curve as shown in FIG. 2 was obtained.

Of the desorption liquid, 25 ortte, initial desorption liquid and 26
3 ml of late-stage desorption liquid was taken out of the system and mixed into the 200 t storage tank of the raw water, while z1 ml of middle-stage desorption liquid was stored in preparation for the next regeneration. Please note that the same applies.

Next, the ion exchange resin was washed by a conventional method, and then the same raw water was passed through it again at 5 VIO of 4.8 to adsorb boron.

Regarding the regeneration after this water flow, the 212r obtained in the previous regeneration
98% (D H2SO41'5
ml was added to make 2251111 regenerating liquid, and after passing this through, 500ffi/extrusion water was passed through, and 212 ml of medium-term desorption liquid was collected in the same manner as the previous time.

After repeating such water passage and regeneration for 4 cycles, the boron concentration of the obtained medium-term desorption liquid 212 was 4.1 asB/
It was l.

Then, when the medium-term desorption liquid was heated and concentrated, 16.
49 basic boric acids were obtained. The sulfuric acid concentration of the residual liquid at that time was about 40%, which was sufficient to be used as the concentrated regenerating liquid of the present invention.

Table 1 Composition of raw water

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the liquid balance of the regenerating liquid of the present invention, and Fig. 2 is a boron desorption curve in an example of the present invention, where the vertical axis shows the boron desorption amount and the horizontal axis shows the liquid amount. . l... Resin column 2... Boron selective ion exchange resin 3... Raw water 4... Treated water A... Initial desorption MB... Middle desorption liquid C... Late desorption liquid D...
・Concentrated regenerated liquid E... Extruded water Figure 1 0 200 40o 60o 800
-→ Liquid volume (m) Procedural supplement (voluntary) July 7, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office/, 4f indications 1982 Patent Application No. 57384 2 Name of the invention Boron selective ion exchange Resin Recycling Method 3 Person who performs Sleeve IL/Relationship with 1 case Applicant ≠ Agent〒113 Please correct the following matters in the subject specification of Sleeve + E. f. The scope of the patent claims is amended as shown in the attached sheet. 2. In the first line of page 6, "Initial desorption amount A" is corrected to "Initial desorption liquid A." 3. On the 4th line from the bottom of page 12, [16, +tJ] is corrected to "4.92". Claims of the above two patents (1) In m#:L of regenerating solution being passed through a boron-selective ion exchange resin that has adsorbed boron.Then, when extruded water is passed through to obtain a boron desorption solution, the desorption solution is Divided into initial desorption solution A, which contains less acid; middle-stage desorption solution B, which has a high boron content; and late-stage desorption solution ti, C, which contains less boron. Take it out of the system, add new concentrated regenerating liquid 1) to the mid-term desorption liquid B, and recirculate it as a regenerating liquid. A method for regenerating a boron-selective ion-exchange resin, comprising: sequentially increasing the boron concentration of the specified desorption solution B by making the total volume of extruded water equal to the total volume of the extruded water. (2) Take out the desorption liquid B with increased boron concentration from the system.
2. The method for regenerating a boron-selective ion exchange resin according to claim 1, wherein boron is precipitated by evaporating the water and recovered as an isomorphic product, and the residual liquid is used as a concentrated regenerating liquid. (3) The method for regenerating a boron-selective ion exchange resin according to claims 1 and 2, wherein the regeneration liquid is sulfuric acid. ]

Claims (3)

[Claims] (1) When a regeneration solution is passed through a boron-selective ion exchange resin that has adsorbed boron, and then extruded water is passed through to obtain a boron desorption solution, the desorption solution is used as an initial desorption solution with a low boron content. With A. It is divided into a medium-term desorption liquid B with a high boron content and a late-stage desorption liquid C with a low boron content. The initial desorption liquid A and the late desorption liquid C are taken out of the yarn, and a new concentrated regenerating liquid is added to the intermediate desorption liquid B, and the mixture is recycled as a regenerating liquid. And by making the total amount of the initial desorption amount A and the late desorption liquid C equal to the total amount of concentrated regeneration liquid and extruded water,
A method for regenerating a boron-selective ion exchange resin, the method comprising increasing the boron concentration of the desorption liquid B in sequence. (2) Take out the desorption liquid B with increased boron concentration from the system,
By evaporating that water! 2. The method for regenerating a boron-selective ion exchange resin according to claim 1, wherein boron is precipitated and recovered as a solid, and the residual liquid is used as a concentrated regenerating liquid. , (3) The method for regenerating a boron-selective ion exchange resin according to claims 1 and 2, wherein the regeneration liquid is sulfuric acid.