JPH0470948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a boron selective adsorption resin having a styrene copolymer as a resin base to absorb hardness components and/or
The present invention also relates to a method for regenerating the resin for stable treatment operations such as boron adsorption treatment in solutions containing heavy metal components or boron adsorption treatment in high-temperature solutions.

Boron is widely distributed in nature and is an essential element for plant growth, but it is known that excessive presence of boron has a negative effect on plant growth. Therefore, when using boron-containing groundwater, geothermal water, wastewater from coal-fired power plants, etc. as irrigation water, it is necessary to keep the boron concentration as low as possible. Furthermore, in the field of magnesium smelting, which uses magnesium dissolved in seawater as a raw material, it is necessary to remove boron from the magnesium solution, since boron present therein has various adverse effects on the product.

In the adsorption treatment of boron from solutions in which these salts coexist or alkaline solutions, commonly used strong and weak basic anion exchange resins have poor selective adsorption ability for boron and cannot be put to practical use.

In recent years, for the purpose of selectively adsorbing boron from these solutions, boron selective adsorption resins have been developed in which a functional group is introduced into a styrene copolymer resin matrix using an amine represented by the following general formula (). In the formula, n = 1 to 6 (integer), R is -CH ₂ [-CH
(OH)]— _n Represents CH ₂ OH or an alkyl group. However, m=0 to 6 (integer).

Diaion CRB-02 (manufactured by Mitsubishi Chemical Industries, Ltd., product name),
Amberlite IRA-743 (manufactured by Rohm and Haas, trade name) and the like are commercially available. All of these are resins that exhibit extremely excellent selective adsorption ability for boron, but they coexist in solutions such as the removal of boron contained in magnesium chloride solutions collected from coal-fired power plant wastewater and seawater. Hardness components such as calcium and magnesium and/or iron as salt,
When heavy metal components such as nickel are present, if these resins are regenerated with an alkaline solution and used in the free amine form, hydroxides such as hardness components will precipitate, reducing resin performance and causing the resin layer to deteriorate. There is a problem with blocking and hardening. Furthermore, when these resins are used to treat high-temperature boron-containing liquids such as wastewater from geothermal power plants, there is a problem that thermal deterioration of the functional groups occurs and the adsorption performance deteriorates over time.

The present inventors used a boron selective adsorption resin obtained by introducing a functional amine represented by the above general formula () into the resin base of such a styrene-based copolymer to remove boron in a solution. As a result of intensive studies to solve these problems that occur during adsorption treatment, we found that the functional amine in the boron selective adsorption resin has the ability to decompose neutral salts with high basicity that are generated during the process of reacting the amine to the resin matrix. It has been found that there exists a portion exhibiting the following, and that this portion is involved in the formation of these hydroxide precipitates during boron adsorption treatment in a solution containing hardness components and/or heavy metal components. That is, when performing boron adsorption treatment in a solution using this resin, the functional amine of the resin is regenerated with an alkaline solution to make it into a free form, and then a neutral salt solution such as sodium chloride is brought into contact with the resin. If the part of the resin functional group amine that shows neutral salt decomposition ability with high basicity is made into a salt-loaded form and then subjected to boron adsorption treatment in a solution containing hardness components and/or heavy metal components, hardness components, etc. It was found that stable boron adsorption treatment could be performed without the generation of hydroxide. Furthermore, in the functional amine in the resin, there is a difference in thermal stability in the free amine form between the part with high basicity that shows neutral salt decomposition ability and the part with low basicity that shows only acid adsorption ability. The part with high basicity undergoes substantial thermal decomposition at temperatures above 40°C, while the part with low basicity remains stable even above 100°C. However, it has been found that when the highly basic part is brought into contact with a neutral salt solution such as sodium chloride to create a salt-loaded form, the thermal stability is improved and it can be practically used even at temperatures above 100°C.

The present invention has been achieved based on such novel findings, and provides a method for stably adsorbing boron in a solution using a boron selective adsorption resin using a styrene copolymer as a resin base. It provides:

The present invention will be explained in detail.

The boron selective adsorption resin used in the present invention is
It is obtained by aminating a resin base obtained by copolymerizing styrene with a crosslinking agent such as divinylbenzene and halomethylating it with chloromethyl methyl ether or the like with a secondary amine represented by the following general formula (). Such secondary amines include N-methyl-D-glucamine, N-ethyl-D-glucamine, N-methyl-D-galactamine, N-methyl-D-mannosamine, di-l-arabitylamine, etc. can be mentioned.

n = 1 to 6 (integer), R is -CH ₂ [-CH(OH)] - _n
Represents CH ₂ OH or an alkyl group. However, m=0
~6 (integer) The amino reaction is performed by a commonly used method. For example, a halomethylated resin base may be reacted with an amine at a temperature of 20 to 100°C for 2 to 20 hours in the presence of a suitable solvent such as dioxane, acetone, methyl ethyl ketone, chloroform, dichloroethane, etc. Further, the resin matrix made of a styrene copolymer may be of a so-called gel type or a highly porous type.

It is necessary to partially salt-load the highly basic amine part of these boron selective adsorption resins, but as a partial salt-loading method, hydrochloric acid, sulfuric acid, etc. are added to the resin after boron adsorption treatment. After contacting with an acid solution to elute boron adsorbed on the resin, it is regenerated with an alkaline solution such as caustic soda or ammonia to free the functional amine of the resin, and then sodium chloride, potassium chloride, sodium sulfate, etc. A solution of a neutral salt selected from halides or sulfates of alkali metals such as potassium sulfate is brought into contact with the resin to load the salt into a portion of the functional amine of the resin that has a high basicity and has the ability to decompose a neutral salt. The concentration of the neutral salt solution used for salt loading may be selected within the range of 1 to 10% by weight, and the amount to be used should be determined by measuring the neutral salt decomposition capacity of the resin functional amine in advance. The amount is appropriately selected within the range of 1 to 10 times that amount, taking into consideration the concentration of other hardness components coexisting in the boron-containing solution, processing flow rate, processing temperature, etc. The resin thus partially salt-loaded is then used for adsorption treatment of boron in the stock solution.

If a boron-containing solution is treated with a partially salt-loaded resin using the method of the present invention, blocking due to the formation of hydroxides of hardness components and heavy metal components coexisting in the solution, and an increase in the pH of the treatment solution will occur. You can perform stable operation without any trouble,
Furthermore, it is possible to process solutions at relatively high temperatures. Furthermore, if the method of the present invention is used, the amount of acid used to elute the adsorbed boron can be reduced and the regeneration rate can be accelerated. The method is industrially extremely useful.

Next, the method of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Boron selective adsorption resin Diaion CRB02 [resin in which a functional group is introduced into a resin base obtained by halomethylating a styrene-divinylbenzene copolymer with a secondary amine represented by the general formula ()] (Mitsubishi Chemical Industries, Ltd.) Take 150ml of free form of 200ml (manufactured by ), trade name), fill it into a jacketed glass column with an inner diameter of 20mmφ and a length of 500mmφ, and add 150ml of 5% hydrochloric acid to it in SV2
After extruding and washing with demineralized water, 150 ml of 5% caustic soda was poured in with SV2 to regenerate. Next, after extrusion washing with demineralized water, 200ml of a 5wt% sodium chloride aqueous solution was poured through SV2, and the product was washed with demineralized water.
Next, 60°C hot water was circulated through the column jacket to maintain the column internal temperature at 60°C. This includes boric acid 1.29
g/(225ppm: B conversion) Sodium chloride 1.3
g/, sodium sulfate 0.9g/, sodium fluoride 0.03g/, magnesium sulfate 0.3g/,
Boron adsorption treatment was carried out by passing a pH 6.0 solution containing 5.3 g of calcium chloride at a flow rate of SV15.
At this time, when the boron concentration in the treated liquid flowing out from the column was measured using the carminic acid colorimetric method, the amount of treated liquid was
Up to 17Bed Volume (hereinafter abbreviated as BV), the boron concentration in the processing solution is below 0.1ppm (B conversion), after which boron leakage gradually occurs until the boron concentration in the processing solution reaches 1ppm (B conversion). The amount was 18 BV. Figure 1 shows the pH of the treatment solution and the breakthrough curve of boron at this time. The pH of the treatment solution was maintained at around 9, and no precipitation due to hydroxide, a hardness component, was observed.
When the boron concentration in the treatment solution reached 10 ppm (in terms of B), the flow of the solution was stopped, and the adsorbed boron was eluted and regenerated; salt loading was carried out, and the stock solution was passed again to perform the boron adsorption treatment. Even when the above steps were repeated a total of 10 times, no hydroxide precipitation of hardness components was observed in the treatment solution or in the resin layer, and stable treatment was achieved.

Example 2 Using the resin and column for which the test in Example 1 was completed, the resin was made into a partially salt-loaded form in the same manner as in Example 1, and the temperature inside the column was maintained at 80°C by passing 80°C hot water through the column jacket. , to which boric acid
0.57g/(100ppm; B conversion), sodium chloride
PH5.0 containing 0.2g/, sodium sulfate 0.3g/
The boron adsorption treatment was carried out by passing a solution of the above at a flow rate of SV20. At this time, analysis of boron in the treated liquid flowing out from the column was carried out in the same manner as in Example 1, and the boron concentration in the treated liquid was 0.1 ppm (B conversion) or less until the treated liquid amount was 23.2 BV. Boron gradually leaks out, and the boron concentration in the processing liquid increases.
The amount of processing liquid up to 1 ppm (B conversion) was 26.0 BV.
When the boron concentration in the treatment solution reached 10 ppm (B conversion), the flow was stopped, and the adsorbed boron was eluted with an acid, regenerated with an alkali, and partially salted with a neutral salt solution, and then the solution was poured again. Boron adsorption treatment was performed by flowing the stock solution. Even after repeating this process 50 times, there was no change in the resin's ability to adsorb boron, and the process was stable.

Comparative Example 1 Using the resin that had been subjected to boron adsorption treatment in Example 2, 150 ml of 5% hydrochloric acid was added in the same column.
The adsorbed boron was eluted by flowing with SV2, then extrusion was washed with demineralized water, and then 5% caustic soda was added.
150 ml was regenerated by flowing through SV2, and the extrusion was washed with demineralized water.

Next, the same boron-containing solution as in Example 1 was added to 60
It was supplied to a column at SV15 at ℃ and subjected to boron adsorption treatment. The pH of the treatment solution and the state of boron breakthrough at this time are shown in broken lines in Figure 1. In this case, the pH of the treatment solution was 12 at the beginning of the flow, and a white precipitate of hydroxide derived from the hardness component of the stock solution was observed in the treatment solution. After the adsorption treatment was completed, when the resin in the column was taken out, similar hydroxide precipitates were found on the resin.
This caused the resin to block and harden.

Comparative Example 2 Diamond ion was added to the column used in Example 1.
CRB02 (manufactured by Mitsubishi Chemical Industries, Ltd., trade name) in free form
Filled with 150 ml, poured 150 ml of 5% hydrochloric acid in SV2, then extruded and washed with demineralized water, then poured 150 ml of 5% caustic soda in SV2, extruded and washed with demineralized water to obtain the same boron-containing material as in Example 2. Stock solution at 80℃
Boron adsorption treatment was performed by passing liquid through SV20. Boron concentration in the treated liquid from the column is 10ppm (B conversion)
At this point, the flow of liquid is stopped, the boric acid is eluted with an acid, the boron is regenerated with an alkali, and the raw liquid is passed through again for boron adsorption treatment.
I did it 50 times. In this method, the part of the amine in the resin with high basicity and poor thermal stability is completely regenerated with an alkaline solution and becomes a free form, so as the number of repetitions increases, the boron adsorption capacity gradually decreases. Comparing the amount of processing solution until the leakage amount of boron in the processing solution reached 1 ppm (in terms of B), the amount at the 50th time was a decrease of 10.2% compared to the first time.

[Brief explanation of the drawing]

Figure 1 shows the PH value of the treatment solution and the boron breakthrough curve in boron adsorption treatment using a boron selective adsorption resin, and the horizontal axis is the amount of treatment solution (BV).
The vertical axis (right) represents the PH value of the treatment liquid, and the vertical axis (left) represents the boron concentration (ppm; B conversion) of the treatment liquid.

Claims (1)

[Scope of Claims] 1. A resin matrix obtained by haloalkylating a styrene copolymer according to the following general formula () In the formula, n=1 to 6 (integer), and R represents _-CH2 [-CH(OH)]- _nCH2OH or _an alkyl group. However, m=0 to 6 (integer). When adsorbing boron in a solution using a boron selective adsorption resin obtained by amination with an amine represented by, the resin is regenerated into a free amine form with an alkaline solution and brought into contact with a neutral salt solution, A method for regenerating a selective boron adsorption resin, which comprises subjecting the resin to an adsorption treatment in the form of a salt-loaded amine portion having a neutral salt decomposition ability. 2. The method according to claim 1, wherein boron is adsorbed from a solution containing boron and a hardness component and/or a heavy metal component. 3. The method according to claim 1, wherein the temperature of the solution containing boron is 40°C or higher.