CN1805925A - Process for purification of aqueous acid solutions - Google Patents

Abstract

A process for the purification of aqueous acid solutions which can dispense with the step of removing chloride ions and which is reduced in the damage to an ion exchanger (such as an ion-exchange column) and thereby permits repeated use of an ion exchanger and lengthened service thereof to bring about a cut in the manufacturing cost. Specifically, a process for the purification of an aqueous solution of an acid (A) by passing an aqueous solution to be treated which contains an acid (A) and a contaminant acid (B) through an ion-exchange column filled with an anion-exchange resin having an anion adsorption selectivity between acids (A) and (B), characterized in that an aqueous solution of acid (A) having a concentration lower than that of the aqueous solution to be treated is passed through the column prior to the passing of the aqueous solution to be treated through the column.

Description

Purification method of acid aqueous solution

technical field

The present invention relates to a method for purifying an aqueous acid solution, and more particularly to a method for effectively and efficiently removing impurities such as sulfuric acid contained in an aqueous solution of an acid such as hydroxyalkanesulfonic acid represented by isethionic acid or alkanesulfonic acid Methods of purification of aqueous solutions of these acids.

Background technique

Aqueous solutions of hydroxyalkanesulfonic acids or alkanesulfonic acids represented by isethionic acid contain sulfuric acid as an impurity in the production process. It has been necessary to remove sulfuric acid from the above aqueous solutions. However, since these acids have similar properties to sulfuric acid, It is difficult to separate by operations such as distillation, so ion exchange resins are used to remove sulfuric acid from the above-mentioned treated aqueous solution. For example, in Patent Document 1, chlorine-type basic anion exchange resins are used to remove sulfuric acid, an impurity contained in methanesulfonic acid aqueous solution. .

However, in this method, since chloride ions are mixed into the aqueous acid solution obtained, it is necessary to remove chloride ions from the aqueous acid solution obtained above by stripping treatment, etc. completely removed from aqueous solution.

On the other hand, as a method of avoiding the mixing of chloride ions into the obtained acidic aqueous solution, it can be considered to use OH type basic anion exchange resin as the ion exchange resin, but if the OH type basic anion exchange resin is used in the purification of the acidic aqueous solution , then the temperature rise caused by the neutralization heat of the ion exchange resin and acid will cause damage to the ion exchanger itself and the column, the service life of the ion exchanger (including the column) will be short, and the cost of manufacturing equipment will increase. The industrial adaptability of the aqueous solution is lacking.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2001-64249

disclosure of invention

The problem to be solved by the invention

Therefore, the purpose of the present invention is to provide unnecessary procedures such as removing chlorine ions, and can reduce the damage of ion exchangers (including columns), reuse ion exchangers, prolong the service life of ion exchangers, and reduce manufacturing costs. A method of purification of an aqueous acid solution.

Solution to the problem

The inventors of the present invention earnestly studied in view of the above-mentioned problems, and completed the present invention. That is, the purification method of the aqueous solution of acid (A) provided by the present invention is by making the treated aqueous solution containing acid (A) and acid (B) as impurity pass through the The purification method of the aqueous solution of the acid (A) carried out by the ion exchange tower of the anion exchange resin (C) of the adsorption selectivity, it is characterized in that, in the aqueous solution ( Hereinafter referred to as "aqueous solution of dilute acid (A)") and then passed through the above-mentioned aqueous solution to be treated.

In the above-mentioned present invention, it is preferred that: the anion exchange resin (C) is an OH-type basic anion exchange resin; the acid concentration of the aqueous solution of the dilute acid (A) is below 30% by mass; the aqueous solution of the dilute acid (A) Obtained by diluting the aqueous solution to be treated; The aqueous solution to be treated is the solution that flows out from the ion exchange tower after the adsorption saturation of the acid (B) as impurity by the anion exchange resin (C); The aqueous solution of the dilute acid (A) is to be treated Treat the aqueous solution and carry out the aqueous solution of the acid (A) that pure water flows out through the ion exchange tower after the purification treatment; Lower than the amount of the ion exchange group total amount of the anion exchange resin (C) in the ion exchange tower; The passing amount of the aqueous solution of dilute acid (A) is to make the total amount of acid and The amount equivalent to the total amount of ion-exchange groups of the anion-exchange resin (C) in the ion-exchange tower; the aqueous solution of dilute acid (A) and the aqueous solution to be treated pass through in an upflow mode; acid (B) is sulfuric acid, and acid (A) ) is an alkanesulfonic acid; acid (A) is a hydroxyalkanesulfonic acid, especially isethionic acid.

In addition, the purification method of the aqueous solution of isethionic acid provided by the invention is by making the treated aqueous solution containing isethionic acid and impurity sulfuric acid pass through the ion exchange resin filled with OH type basic anion exchange resin for isethionic acid and sulfuric acid. The method for purifying an aqueous solution of isethionic acid by means of an exchange column is characterized in that the aqueous solution to be treated is passed through the aqueous solution of isethionic acid having a concentration lower than that of the aqueous solution to be treated.

The effect of the invention

The effect of the present invention is to provide an acid that does not need to remove redundant processes such as chlorine ions, and can reduce the damage of ion exchangers (including columns), reuse ion exchangers, prolong the service life of ion exchangers, and reduce manufacturing costs. Methods of purification of aqueous solutions.

The best way to practice the invention

In the present invention, the aqueous solution to be treated as the object of purification, that is, the aqueous solution of acid (A) containing acid (B) as an impurity, is not particularly limited, as long as it is difficult to remove the impurity contained in the aqueous solution to be treated by distillation or the like. An aqueous solution of the acid (A) of the acid (B) may be used, for example, an aqueous solution containing sulfuric acid containing alkanesulfonic acid or hydroxyalkanesulfonic acid as a main component. In addition, the above-mentioned aqueous solution to be treated may be a solution flowing out of the ion exchange tower after the adsorption of the acid (B) as an impurity by the anion exchange resin (C) is saturated in the method of the present invention described below.

The aqueous solution of the above-mentioned alkanesulfonic acid or hydroxyalkanesulfonic acid contains a trace amount of sulfuric acid as an impurity due to its production method. The sulfuric acid was removed from the aqueous solution.

Therefore, specific examples of the acid (B) as an impurity contained in the aqueous solution to be treated in the present invention include, for example, sulfuric acid.

The present invention passes the treated aqueous solution containing the acid (A) and the acid (B) as an impurity through filled with adsorption selectivity to the acid (A) and the acid (B) having anions (that is, adsorption of the acid (A) and the acid (B) (B) the ability of different) anion exchange resin (C) to purify the aqueous solution of acid (A) in the ion exchange column. That is, an aqueous solution of the acid (A) in which the content of the acid (B) in the aqueous solution to be treated is significantly reduced is obtained.

The anion exchange resin (C) used in the present invention is not particularly limited, as long as it has anion adsorption selectivity to acid (A) and acid (B), it can be used in order to save the process of removing chloride ions, etc., preferably It is an OH type basic anion exchange resin, and for example, an OH type weakly basic anion exchange resin and the like can be used. More specifically, it is preferable to use, for example, Duolite A-561 (trade name) manufactured by Rom And Haus Co., Ltd., Diayion WA-20 (trade name) manufactured by Mitsubishi Chemical Co., Ltd., and commercially available OH-type weak gels of similar properties. Basic anion exchange resin, etc.

The purification method of the present invention can reduce the damage of ion exchanger (comprising column), reuse ion exchanger, prolong the service life of ion exchanger, reduce the manufacturing cost of purified acid (A) aqueous solution, in the above-mentioned When the aqueous solution to be treated passes through the ion exchange tower filled with the anion exchange resin (C), the aqueous solution of the dilute acid (A) is first allowed to pass through the ion exchange tower, and then the aqueous solution to be treated is allowed to pass through the ion exchange tower.

The dilute acid (A) aqueous solution is not particularly limited, and may have, for example, a concentration of the acid (A) of 30% by mass or less, preferably 20% by mass or less. If it is an aqueous solution of acid (A) with a concentration of more than 30% by mass, the anion exchange resin, especially the OH-type basic anion exchange resin, will react with the acid (B), and exothermic heat will cause expansion and other phenomena, resulting in ion exchangers and columns. damage, thereby shortening the life of the device. If the concentration of the acid (A) is too low, the industrial purification efficiency will decrease, so it is preferably at least 5% by mass.

The dilute acid (A) aqueous solution may be a pure or high-purity acid (A) aqueous solution, or may be an aqueous solution obtained by diluting the aqueous solution to be treated. In addition, as described later, the dilute aqueous acid (A) solution may be an aqueous acid (A) solution obtained by passing pure water through an ion exchange tower after purifying the aqueous solution to be treated.

In the purification method of the present invention, the aqueous solution of the above-mentioned dilute acid (A) is passed through the ion exchanger, and then the aqueous solution to be treated is passed through the ion exchanger.

Here, the structure of the aqueous solution of purified acid (A) in this invention is demonstrated. Take isethionic acid in hydroxyalkanesulfonic acid as acid (A) and sulfuric acid as acid (B) as an example, and as the aqueous solution to be treated, the aqueous solution of isethionic acid containing a trace amount of sulfuric acid and dilute acid (A ) dilution of the aqueous solution to be treated is described as an example, but the present invention is not limited to these examples.

First above-mentioned dilute aqueous solution of isethionic acid is passed through the ion exchange tower filled with the anion-exchange resin (C) with the adsorption selectivity of anion, because the adsorption selectivity of anion-exchange resin in sulfuric acid and isethionic acid is high to sulfuric acid, Therefore, the ion-exchange groups of the anion-exchange resin on the side close to the introduction port in the ion-exchange tower are sequentially replaced by sulfuric acid. Sulfuric acid is an impurity, its amount is small, and isethionic acid moves faster than sulfuric acid in the ion exchange tower, so except for the ion exchange group near the inlet, the ions until the outlet of the ion exchange tower The exchange groups were all replaced by isethionic acid.

At this time, if the passing amount of the aqueous solution of the dilute acid (A) makes the total amount of the acid (A) in the aqueous solution of the dilute acid (A) lower than the ion exchange group of the anion exchange resin (C) in the ion exchange tower If the total amount is used, there will be unsubstituted ion exchange groups remaining on the outlet side of the ion exchange tower, and the ion exchangers will be damaged due to the reaction with sulfuric acid in the treated aqueous solution that passes through later, so it is better to set a dilute acid The throughput of the aqueous solution of (A) is to make the total amount of the acid (A) in the aqueous solution of the dilute acid (A) not less than the amount of the ion exchange group total amount of the anion exchange resin (C) in the ion exchange tower . Considering the industrial purification efficiency, the total amount of the acid (A) can be slightly lower than the total amount of the ion-exchange groups within the allowable range, and of course such a range is included in the above-mentioned preferred range.

In addition, if the dilute isethionic acid aqueous solution passes through in a large amount, the total amount of the isethionic acid in the dilute isethionic acid aqueous solution exceeds the total amount of ion exchange groups of the anion exchange resin (C) in the ion exchange tower, then The dilute aqueous solution of isethionic acid directly flows out of the ion exchange tower, and the industrial purification efficiency of the aqueous solution of isethionic acid decreases. In addition, the amount of ion exchange resin replaced by the impurity sulfuric acid contained in it also increases, so it is better to design The passing amount of the aqueous solution of the acid (A) of constant dilute is to make the total amount of the acid in the aqueous solution of the dilute acid (A) and the ion exchange group total amount equivalent of the anion exchange resin (C) in the ion exchange tower quantity. Considering the industrial purification efficiency of isethionic acid, the above-mentioned isethionic acid may slightly exceed this equivalent within the allowable range, and of course such a range is included in the above-mentioned preferred range.

By passing the dilute aqueous solution of isethionic acid in this way, the anion exchange resin is temporarily replaced by isethionic acid, so that the anion exchange resin and the like are hardly damaged even if the aqueous solution to be treated is passed thereafter.

Next, an isethionic acid aqueous solution containing sulfuric acid, which is an aqueous solution to be treated, is passed through the ion exchange tower in this state. As mentioned above, the anion exchange resin has been temporarily replaced by isethionic acid, so the concentration of isethionic acid in the aqueous solution to be treated is not particularly limited, it can be a dilute aqueous solution of isethionic acid, or it can be a high concentration of isethionic acid As the aqueous solution, from the viewpoint of industrial purification efficiency, it is preferable to use a high-concentration aqueous solution of isethionic acid. Specifically, the concentration is preferably more than 30% by mass, more preferably at least 40% by mass. There is no specific upper limit to the concentration of isethionic acid in the aqueous solution to be treated, but if the concentration is too high, the industrial purification efficiency will decrease, so it is preferably 60% by mass or less.

The isethionic acid aqueous solution as the aqueous solution to be treated is passed through the ion exchange tower, and the isethionic acid with a fast moving speed first arrives at the outflow outlet of the ion exchange tower (at this time, for example, it can be known by the following method, that is, measure the effluent pH, confirm that the pH is below 3), so if the effluent is collected from here, a refined isethionic acid aqueous solution with very little sulfuric acid content can be obtained.

The ion exchange group of the ion exchange resin passes through the isethionic acid aqueous solution containing sulfuric acid as the aqueous solution to be treated, and the isethionic acid adsorbed on the ion exchange resin is sequentially removed from the inlet side of the ion exchange tower to the outlet side. Sulfuric acid displacement, so the collection of aqueous isethionic acid can be stopped when all ion exchange groups have been displaced to sulfuric acid. This time can be known by analyzing the concentration of sulfuric acid in the collected liquid at any time. If the reproducibility is guaranteed under the same conditions, it can be known by conducting a preliminary experiment to analyze the concentration of sulfuric acid in the treated aqueous solution and calculating the throughput of the treated aqueous solution. The time the collection stopped.

The ion-exchange resin after stopping the collection can be regenerated by a known method, for example, by sodium hydroxide aqueous solution, etc., and the above-mentioned operation is repeated.

In the purification method of the present invention, from the viewpoint of further reducing damage to the ion exchanger, etc., the aqueous solution to be treated preferably passes through the ion exchange tower in an upflow (upward flow) manner.

Example

Hereinafter, examples of the present invention will be given to further describe the present invention, but the present invention is not limited to these examples.

[Example 1]

In a polyvinyl chloride resin column with a volume of 31.4L (inner diameter 20cm and a height of 1m), 25.5LOH type weakly basic anion exchange resin (manufactured by Roma AndHaus, trade name: デュオライト A-561) is charged to form an ion exchange tower. An aqueous solution having an isethionic acid concentration of 46% by mass and a sulfuric acid concentration of 1.6% by mass was prepared as an aqueous solution to be treated, and an aqueous solution obtained by diluting the aqueous solution to be treated to 2 times with pure water was used as a diluted isethionic acid aqueous solution.

Pass 24.5L of the above-mentioned diluted isethionic acid aqueous solution through the above-mentioned ion exchange tower (11L/hr) in an upflow manner, and then pass through the above-mentioned treated aqueous solution (16L/hr) in an upflow manner. The pH of the effluent from the tower was measured, and when the pH was lower than 3, the effluent was collected and analyzed to obtain 80 kg of a refined (high-purity) isethionic acid aqueous solution with a concentration of isethionic acid of 44% by mass and a concentration of sulfuric acid of 0.0034% by mass.

Then, pure water was passed through in a co-current manner (downward flow), and the residual liquid of the isethionic acid aqueous solution in the ion exchange column was eluted. Then, pass 1.5N aqueous sodium hydroxide solution (60L/hr) in a downstream manner to restore the ion exchange group of the ion exchange resin to the OH type, and pass pure water (60L/hr) in a downstream manner until the effluent It is neutral and regenerates ion exchange resins.

Then, the above operation was repeated in the same manner to continuously produce a high-concentration isethionic acid aqueous solution with an extremely low concentration of impurity sulfuric acid. As a result, the concentration of isethionic acid and sulfuric acid hardly changed even up to the 75th batch, and 75 kg of high-purity isethionic acid was obtained. For ethanesulfonic acid aqueous solution, the recovery rate of high-purity isethionic acid aqueous solution caused by the damage of ion exchange resin decreased by less than 10%.

[Example 2]

After obtaining 80 kg of refined isethionic acid aqueous solution (a) in the same manner as in Example 1, the above-mentioned treated aqueous solution was passed through an ion exchange tower. The treated aqueous solution had the same composition, and 78 kg of an isethionic acid aqueous solution (b) having a concentration of 46% by mass of isethionic acid and a concentration of sulfuric acid of 0.95% by mass was obtained during this period. Then, 18L of pure water (16L/hr) was passed through in a downstream manner, and as a result, 22kg of an isethionic acid aqueous solution (c) with a concentration of 46% by mass of isethionic acid and a concentration of sulfuric acid of 1.6% by mass was obtained, and 25L of pure water was passed through in a downstream manner. Pure water (16 L/hr) resulted in 28 kg of dilute isethionic acid aqueous solution (d) having a concentration of isethionic acid of 25% by mass and a concentration of sulfuric acid of 0.8% by mass.

In the operation so far, the recovery rate of isethionic acid was calculated from the total amount of isethionic acid passing through the ion exchange tower and the amount of isethionic acid contained in (a) to (d) above, and it was 99% by mass. Then, pass 1.5N aqueous sodium hydroxide solution (60L/hr) in a downstream manner to restore the ion exchange groups of the ion exchange resin to the OH type, and pass pure water (60L/hr) in a downstream manner until the effluent It is neutral and regenerates ion exchange resins.

Then, as the second operation, using (b) to (d) obtained by the above operation and the above-mentioned aqueous solution to be treated, pass through the ion exchange tower in the order of (d), (b), (c) and the aqueous solution to be treated, By performing the same operation as above, 100 kg of an isethionic acid aqueous solution (e) having an isethionic acid concentration of 45% by mass and a sulfuric acid concentration of 0.020% by mass, and 78 kg of isethionic acid having a concentration of 46% by mass and a sulfuric acid concentration of 0.95% by mass were obtained. Aqueous solution of ethanesulfonic acid (f), then pure water is passed through ion exchange tower, obtains the aqueous solution (g) of 22kg isethionic acid concentration 46 mass %, sulfuric acid concentration 1.6 mass %, 28kg isethionic acid concentration 23 % by mass, a dilute aqueous solution of isethionic acid (h) having a sulfuric acid concentration of 0.810% by mass. In addition, the recovery rate of isethionic acid was 99% by mass.

Then, after regeneration in the same manner as above, the same operation as the second time was repeated 10 times. As a result, aqueous solutions (e) to (h) of isethionic acid were obtained in the same way as the second time. In addition, the recovery rate of isethionic acid All are 99% by mass.

[Comparative Example 1]

Except that dilute isethionic acid is not passed through the treated aqueous solution from the beginning, it is carried out in the same manner as in Example 1. As a result, due to the heat generation and expansion of the ion exchange resin, cracks appear in the ion exchange tower, and the treated aqueous solution cannot be processed. purification treatment.

Possibility of industrial use

By adopting the present invention, it is possible to provide unnecessary procedures such as removing chlorine ions, and to reduce damage to ion exchangers (including columns), to reuse ion exchangers, to prolong the service life of ion exchangers, and to reduce manufacturing costs. Methods of purification of aqueous solutions.

Claims (14)

1. the purification process of the aqueous solution of acid (A), it be make contain acid (A) and as the processed water solution of the acid (B) of impurity by having filled the purification process that acid (A) and sour (B) is had the aqueous solution of the acid (A) that the ion exchange tower of the anionite-exchange resin (C) of anionic adsorption selectivity carries out, it is characterized in that, after by the aqueous solution of the acid (A) lower, pass through above-mentioned processed water solution than the concentration of described processed water solution.

2. the purification process of the aqueous solution of acid as claimed in claim 1 (A), its feature are that also anionite-exchange resin (C) is OH type basic anion exchange resin.

3. the purification process of the aqueous solution of acid as claimed in claim 1 or 2 (A), its feature also be, than the acid concentration of the aqueous solution of the low acid of the concentration of processed water solution (A) below 30 quality %.

4. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～3, its feature also is, obtains by dilution processed water solution than the aqueous solution of the low acid of the concentration of processed water solution (A).

5. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～3, its feature also is, processed water solution be anionite-exchange resin (C) to as the saturated back of absorption of the acid (B) of impurity from the effusive solution of ion exchange tower.

6. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～3, its feature also is, than the aqueous solution of the low acid of the concentration of processed water solution (A) be after processed water solution is carried out purification process with pure water by ion exchange tower and the aqueous solution of effusive acid (A).

7. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～4, its feature also is, is to make the total amount of the aqueous acid medium of rare acid (A) be not less than the amount of the ion-exchange group total amount of the anionite-exchange resin (C) in the ion exchange tower than the throughput of the aqueous solution of the low acid of the concentration of processed water solution (A).

8. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～4, its feature also is, is the amount that makes the ion-exchange group total amount equivalent of the total amount of aqueous acid medium of rare acid (A) and the anionite-exchange resin (C) in the ion exchange tower than the throughput of the aqueous solution of the low acid of the concentration of processed water solution (A).

9. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～8, its feature also is, passes through than the aqueous solution and the above stream mode of processed water solution of the low acid of the concentration of processed water solution (A).

10. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～9, its feature is that also acid (B) is sulfuric acid.

11. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～10, its feature is that also acid (A) is alkansulfonic acid.

12. as the purification process of the aqueous solution of each the described acid (A) in the claim 1～10, its feature is that also acid (A) is the hydroxyl alkansulfonic acid.

13. the purification process of the aqueous solution of acid as claimed in claim 12 (A), its feature are that also acid (A) is isethionic acid.

14. the purification process of the aqueous solution of isethionic acid, it is the purification process that makes the aqueous solution of the isethionic acid that contains isethionic acid and undertaken by the ion exchange tower of having filled at isethionic acid and vitriolic OH type basic anion exchange resin as the vitriolic processed water solution of impurity, it is characterized in that, after by the aqueous solution of the isethionic acid lower, pass through above-mentioned processed water solution than the concentration of described processed water solution.