JPH09225298A - Resin for adsorbing arsenic and method for recovering arsenic from solution containing arsenic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively recover arsenic eliminating the need of using large amount of a flocculating agent like conventional flocculating and settling method in order to reduce an arsenic concn. in a soln. to less than a regulated value. SOLUTION: In the resin for adsorbing arsenic, iron and hydroxyl ion are supported with a cation exchange resin and/or chelate resin. Besides, in this method for removing arsenic from the soln. containing arsenic, the soln. containing arsenic is brought into contact whit the resin for adsorbing arsenic in which iron and hydroxyl ion are supported with the cation exchange resin and/or the chelate resin and arsenic in the soln. is adsorbed on the resin for adsorbing arsenic and recover.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin for adsorbing arsenic and a method for recovering arsenic from a solution containing arsenic.

[0002]

2. Description of the Related Art Arsenic and its compounds are contained in pyrite, phosphate rock, etc., and a large amount of arsenic is contained in wastewater of manufacturing plants of phosphorus and phosphorus compounds and sulfuric acid manufacturing plants using these as raw materials. there is a possibility. Further, since arsenic is used as a semiconductor raw material, a large amount of arsenic may be contained in wastewater of a semiconductor manufacturing / processing factory. Furthermore, arsenic may be contained in mine wastewater, hot spring water, and the like.

However, since arsenic is an environmental pollutant having a strong toxicity, strict regulation for arsenic in waste water is set, and the allowable amount thereof is regulated to 0.1 mg / liter or less.

As a method of recovering arsenic contained in wastewater,
The coprecipitation collection method of precipitating arsenic together with hydroxides of metals such as iron, aluminum, calcium, and magnesium, the method of adsorbing and collecting arsenic by adding an arsenic adsorbent, the method of adsorbing using an anion exchange resin, etc. Are known. As the adsorbent used in the above method of adsorbing and recovering arsenic by an adsorbent, a hydrous oxide of a rare earth element or an adsorbent in which this is supported on an organic polymer porous carrier (Japanese Patent Laid-Open No. 61-18793).
No. 1), an adsorbent composed of a phenolic resin and a metal hydroxide (Japanese Patent Laid-Open No. 59-69151), a cation exchange resin carrying a metal such as iron or zirconium, activated alumina, activated carbon and the like. .

[0005]

However, in the coprecipitation trapping method and the method of adding an arsenic adsorbent, in order to reduce arsenic to a wastewater standard value of 0.1 mg / liter or less, a large amount of metal hydroxide is added. However, there is a problem in that post-treatment of a large amount of sludge produced is not easy.

Further, in the method using a hydrous oxide of a rare earth element as an adsorbent, the adsorbent is packed in a column because the rare earth element as a raw material of the adsorbent is expensive and the particle size of the adsorbent is small. If used for a long time, the pressure loss becomes large, and there is a problem that it is not practical. Further, the ion exchange method in which an anion exchange resin is used for adsorption has a problem that the presence of a coexisting salt significantly reduces the arsenic adsorption effect.

As a result of earnest studies to solve the above problems, the present inventors have found that cation exchange resins and chelate resins have
Resin having a structure supporting iron and hydroxyl ions is excellent in the ability to recover arsenic from an arsenic-containing solution,
Such resins can be manufactured inexpensively and easily,
Moreover, by using this resin, it was found that the above-mentioned drawbacks of the conventional method using an arsenic adsorbent or anion exchange resin can be solved, and arsenic can be effectively adsorbed and recovered,
The present invention has been completed.

[0008]

That is, the resin for adsorbing arsenic of the present invention is characterized in that a cation exchange resin and / or a chelate resin carry iron and hydroxyl ions. The method for recovering arsenic from a solution containing arsenic of the present invention is a method of contacting a solution containing arsenic with a resin for adsorbing arsenic in which iron and hydroxyl ions are supported on a cation exchange resin and / or a chelate resin, The arsenic is recovered by being adsorbed on an arsenic adsorption resin.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The resin for adsorbing arsenic of the present invention can be obtained by supporting an iron compound on a cation exchange resin or a chelate resin and then treating with an alkali. Examples of the iron compound include ferrous oxide, ferrous hydroxide, ferrous sulfide, ferrous fluoride, ferrous chloride, ferrous bromide, ferrous iodide, ferrous nitrate. , Ferrous sulfate, ferrous carbonate, ferric oxide, ferric fluoride, ferric chloride, ferric bromide, ferric nitrate, ferric sulfate and the like can be used.

The above iron compounds can be used even if they are insoluble or sparingly soluble. Among the above iron compounds, ferric chloride, ferric sulfate, ferric nitrate, ferrous chloride, ferrous sulfate and ferrous nitrate are preferable.

As the cation exchange resin supported by the iron compound, a resin having a cation exchange group such as a sulfonic acid group or a carboxylic acid group in the resin matrix is used. As the resin matrix of the cation exchange resin, generally, for example, styrene resin, styrene copolymer such as styrene-divinylbenzene copolymer, phenol resin, acrylic acid resin, methacrylic acid resin, epoxy resin, resorcin resin, chloride. Vinyl resin, urea resin, etc. are used.

On the other hand, the chelate resin generally contains a metal-coordinating atom such as oxygen, nitrogen, sulfur or phosphorus in the resin matrix.
It is a resin having the above functional groups. Typical functional groups are carboxylic acid groups and salts thereof, amide groups, sulfonic acid groups, hypophosphorous acid groups, phosphorous acid groups, primary amine groups, secondary amine groups, tertiary amine groups, azo groups. , Oxime group, amidoxime group, imine group, enamine group, thioalcohol group, thioether group, thioaldehyde group, thioketone group, thiocarboxylic acid group and its salts, dithiocarboxylic acid group and its base, thioamide group, thiocyanate group, isothiocyanate group Although it is a nato group or the like, it is not limited to these as long as it has a coordinating property with respect to a metal.

Common chelating resin functional groups include iminodicarboxylic acid groups such as iminodiacetic acid and iminodipropionic acid and salts thereof, aminophosphoric acid groups and salts thereof,
Examples thereof include aminoalkylene phosphoric acid groups and salts thereof, iminoalkylenecarboxylic acid groups such as iminoacetic acid and iminopropionic acid and salts thereof, thiol groups, dithiocarboxylic acid groups and salts thereof, and the like. Examples of the resin matrix of the chelate resin include styrene-divinylbenzene copolymer, epoxy resin, phenol resin, resorcin resin, vinyl chloride resin, acrylic acid resin, methacrylic acid resin, urea resin and the like.

As the above-mentioned cation exchange resin and chelate resin used for the resin for adsorbing arsenic of the present invention, commercially available products can be used as they are, but among them, chelate resins are preferable.

As a method of supporting the iron compound on the cation exchange resin or the chelate resin, there is a method of bringing the cation exchange resin or the chelate resin into contact with an aqueous solution containing the iron compound. A kneading method is adopted. By carrying an alkali treatment after supporting an iron compound, the arsenic-adsorbing resin of the present invention in which a cation exchange resin or a chelating resin is supported with iron and hydroxyl ions is obtained. When iron hydroxide is used as the iron compound to be initially supported on the cation exchange resin or the chelate resin, it means that iron and hydroxyl ions are already supported before the alkali treatment. By the treatment, the activity against arsenic is increased and the amount of arsenic adsorption is improved.

Examples of the alkali for treating the cation exchange resin or chelate resin carrying the iron compound with alkali include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide and ammonium hydroxide. Examples thereof include sodium hydroxide and potassium hydroxide.

The method for recovering arsenic of the present invention is a method of contacting the arsenic-adsorbing resin with a solution containing arsenic, and adsorbing arsenic in the solution to the resin to recover the arsenic. , Using only a cation exchange resin supporting iron and hydroxyl ions, using only a chelating resin supporting iron and hydroxyl ions, or using a mixture of both as appropriate. good.

As a method of treating the solution containing arsenic with the resin, a method of passing the solution containing arsenic through the column filled with the resin to bring the solution into contact with the resin, or a method containing the solution containing arsenic with the resin The method of adding a solution and bringing the solution into contact with the resin is generally adopted. In order to efficiently adsorb arsenic to the resin, it is preferable to adjust the pH of the solution to 4 to 10 when the solution containing arsenic is brought into contact with the adsorption resin. Examples of the alkali used for adjusting the pH of the solution include lithium hydroxide, sodium hydroxide,
Potassium hydroxide, magnesium hydroxide, calcium hydroxide, ammonium hydroxide and the like are used, but sodium hydroxide and potassium hydroxide are particularly preferable. Examples of the acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid and the like, with hydrochloric acid and sulfuric acid being particularly preferable.

The solution containing arsenic may be passed through the column from the upper side to the lower side of the column or from the lower side to the upper side of the column. Further, the passage rate (water passage rate) of the solution per 1 liter of resin is preferably 1 to 50 liters / liter-R per hour.

The arsenic-adsorbing resin that has adsorbed arsenic has a pH of 1
Arsenic adsorbed on the resin can be recovered by treating with an alkali having a pH of 0 or more, more preferably a pH of 13 or more. The arsenic-adsorbing resin of the present invention, even if treated with an alkali to recover arsenic from the resin that has adsorbed arsenic, iron carried on the resin does not elute from the resin, and after recovering arsenic, It can be reused immediately by performing a treatment such as washing with ion-exchanged water.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Examples 1 to 3 In 300 ml of an aqueous ferric chloride solution (15% aqueous solution), a styrene-divinylbenzene copolymer resin was used as a resin matrix, and a chelate resin having an aminophosphoric acid group as a functional group (particle size 20 to 20). (48 mesh) 300 ml and after stirring for 1.5 hours, the chelate resin is filtered off, washed thoroughly with ion-exchanged water, and 300 ml of a 1 mol / liter sodium hydroxide aqueous solution is added for 1 hour. It was stirred. Then, the chelate resin was filtered off and washed with ion-exchanged water until the pH of the wash water became 9 or less.

5 ml of the resin obtained as described above was added to 500 ml of a solution containing arsenous acid and sodium chloride having the concentrations shown in Table 1 (arsenic concentration 48 mg / liter), and the mixture was stirred for 3 hours and then allowed to stand for 5 minutes. Then, the arsenic concentration in the supernatant water was measured by the atomic absorption method, and the arsenic adsorption amount per 1 ml of the resin was calculated from the measured value.
The results are shown in Table 1.

[0024]

[Table 1]

Comparative Examples 1 to 3 The same tests as in Examples 1 to 3 were conducted using the chelate resins obtained in the same manner as in Examples 1 to 3 except that the treatment with the aqueous sodium hydroxide solution was not carried out. The results are shown in Table 1.

Examples 4 to 6 To 500 ml of an aqueous ferric sulfate solution (10% aqueous solution), 500 ml of a chelate resin having a phenolic resin as a base and having an iminodiacetate group as a functional group (particle size 20 to 48 mesh) was added. After stirring for 1.5 hours, the chelate resin is filtered off, washed thoroughly with ion-exchanged water, and then a 1 mol / liter sodium hydroxide aqueous solution 3
00 ml was added and stirred for 2 hours. Then, the chelate resin was filtered off and washed with ion-exchanged water until the pH of the wash water became 9 or less.

3 ml of the resin obtained as described above was added to 500 ml of a solution containing arsenous acid and sodium sulfate having a concentration shown in Table 1 (arsenic concentration: 52 mg / liter), and the mixture was stirred for 1.5 hours and then added to 5 ml. The mixture was allowed to stand for a minute, the arsenic concentration in the supernatant water was measured by an atomic absorption method, and the arsenic adsorption amount per 1 ml of the resin was calculated from the measured value. Table 2 shows the results.

[0028]

[Table 2]

Comparative Examples 4 to 5 Tests were conducted in the same manner as in Examples 4 to 5 except that an acrylic acid weak anion exchange resin (20 to 35 mesh) was used. The results are also shown in Table 2.

Example 7 A chelate resin having a styrene-divinylbenzene copolymer resin as a resin matrix and an iminodiacetic acid group as a functional group (particle size 20 to 35 mesh) in 1000 ml of an aqueous ferric nitrate solution (10% aqueous solution). ) 1000 ml was added, and the mixture was stirred for 1.5 hours, then the chelate resin was filtered off, thoroughly washed with ion-exchanged water, 300 ml of a 1 mol / liter sodium hydroxide aqueous solution was added, and the mixture was stirred for 1 hour. . Then, the chelate resin was filtered off and washed with ion-exchanged water until the pH of the wash water became 9 or less.

100 ml of this resin is used for an inner diameter of 25 m
m glass column, and arsenic-containing wastewater (arsenic 2.6 mg / liter, semiconductor factory wastewater with pH = 8.3. Filtered and used) was applied to this column in a downward flow of 2 liter / hour.
Water was passed at a rate of liter-R. FIG. 1 shows the relationship between the flow rate of waste water to the column and the concentration of arsenic in the waste water flowing out from the column (curve a-1). Further, when 2 ml / liter of an aqueous sodium hydroxide solution was passed through the column after passing the arsenic-containing wastewater at a flow rate of 1 liter / liter-R in an amount of 5 times the amount of the resin to regenerate the resin, Of the 33 mg of arsenic adsorbed on the resin, 32.8 mg of arsenic could be recovered. After the regenerated resin was washed again by passing 10 times as much ion exchange water as the resin at a flow rate of 2 liter / liter-R per hour, the arsenic-containing waste water was again passed under the same conditions as above. The relationship between the flow rate of waste water to the column and the concentration of arsenic in the waste water flowing out from the column at this time is also shown in FIG. 1 (curve a-2).

Comparative Example 7 Arsenic-containing wastewater was treated in the same manner as in Example 7 except that a phenol resin containing hydrous zirconium oxide (particle size: 14 to 48 mesh) was used. The relationship between the water flow rate of the waste water to the column and the arsenic concentration in the waste water flowing out from the column is also shown in FIG. 1 (curve b).

Example 8 100 ml of a chelate resin (20 to 48 mesh) containing 30% by weight of ferric hydroxide (added by a kneading method), a resin matrix of which was a phenol resin and an iminodiacetic acid group was a functional group, was added. After being placed in 500 ml of a 5% aqueous solution of calcium hydroxide and stirred for 1.5 hours, the resin was filtered off and sufficiently washed with ion-exchanged water. 5 ml of this resin was added to 500 ml of a solution containing 55 mg / liter of arsenous acid and 30,000 mg / liter of sodium sulfate, stirred for 3 hours and then allowed to stand for 5 minutes, and the arsenic concentration in the supernatant water was measured by atomic absorption spectrometry. The amount of arsenic adsorbed per milliliter of the resin was calculated from the measured values. As a result, the arsenic adsorption amount per 1 ml of the resin was 1.58 mg / ml-R.

Example 9 A chelate resin containing ferric hydroxide similar to that in Example 8 was used without alkali treatment, and the same test as in Example 8 was conducted. The amount of arsenic adsorbed per milliliter of resin is 1.
It was 26 mg / mL-R.

[0035]

As described above, according to the method of the present invention, in order to reduce the concentration of arsenic in a solution to a regulated value of 0.1 mg / liter or less, a large amount of agglomeration like the conventional agglomeration-precipitation method is performed. Arsenic can be effectively recovered without the need to use an agent. Further, since complicated processing work and special processing equipment which requires a large amount of cost for installation are not required, efficient processing can be performed at low cost. Further, since the resin for adsorbing arsenic of the present invention does not elute the iron supported on the resin even if the resin is washed with an alkali to recover the arsenic adsorbed on the resin, the resin adsorbing arsenic After performing the process of recovering arsenic from the product, it can be reused immediately by passing through the steps of cleaning, which greatly simplifies the resin recycling process and also allows the resin to be recycled repeatedly. Also, there is an effect that the arsenic adsorption ability is not significantly reduced.

[Brief description of drawings]

FIG. 1 is a graph showing a water passage ratio of waste water and an arsenic concentration in waste water flowing out of a column in Example 7 and Comparative Example 7.

Claims (2)

[Claims] 1. A resin for adsorbing arsenic, characterized in that a cation exchange resin and / or a chelate resin carry iron and hydroxyl ions. 2. A solution containing arsenic is brought into contact with a resin for adsorbing arsenic in which a cation exchange resin and / or a chelate resin carry iron and hydroxyl ions, and the arsenic in the solution is adsorbed by the resin for adsorbing arsenic. A method for recovering selenium from a solution containing arsenic, characterized by recovering.