JP2017035678A - Method for purifying zinc-containing aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a zinc-containing solution, capable of reducing the zinc concentration of an aqueous solution containing zinc and a compound having ability for forming a complex with zinc to 2 mg/L or less.SOLUTION: To an aqueous solution containing zinc and a compound having ability for forming a complex with zinc, a salt of dithiocarbamic acid and an inorganic coagulant in an amount equal to or larger than the content of the compound having ability for forming a complex with zinc are added, and solid matter is then removed.SELECTED DRAWING: None

Description

  The present invention relates to a compound capable of complexing with zinc, and a purification method that makes it possible to remove zinc from an aqueous solution containing zinc.

  The aqueous solution containing zinc is sent to a wastewater treatment facility, for example, iron ions are added to make it alkaline, and the zinc ions are treated as precipitates together with iron ions and other contained ions as hydroxides. The method of releasing after separating has been performed.

  The effluent standard for zinc content was conventionally set at 5 mg / L, but the effluent standard was strengthened from the viewpoint of aquatic life conservation and was changed to 2 mg / L in 2006. However, 5 mg / L has been applied as a provisional drainage standard for specific business establishments belonging to 10 industries that are found to be extremely difficult to meet the uniform drainage standard. In recent years, 2 mg / L, which is a wastewater standard for zinc, has been required, and the importance of wastewater treatment is increasing.

  By the way, drainage water from plating factories, electronic parts / machine parts manufacturing factories, automobile factories, etc. includes organic acids such as citric acid and gluconic acid, ethylenediaminetetraacetic acid (hereinafter abbreviated as EDTA), cyanide, amine, ammonia and polyphosphorus. There are many cases in which compounds having the ability to complex with zinc, such as acids, are included and cannot be treated by the hydroxide method as described above.

  On the other hand, there is a method of insolubilizing zinc after a compound having a complex forming ability with zinc is treated by a chemical treatment and a compound having a complex forming ability with zinc. However, even in chemical treatment, for example, oxidation method with chlorine-based chemicals, electrolytic oxidation method, hydrogen peroxide-ferrous salt method, ozone oxidation method, wet oxidation method, etc., inhibition of oxidation reaction by coexisting heavy metal elements, There are problems such as scale generation.

  Examples of the technology for removing various heavy metal elements contained in such waste water include, for example, an aggregating and removing method by adding an inorganic or organic flocculant, an electrolytic removing method, activated carbon, an inorganic adsorbent, or an organic polymer material. Adsorption removal methods, dry solidification methods that heat and evaporate wastewater, reverse osmosis methods using membranes, electrodialysis, or ultrafiltration methods have been proposed.

  When the above-described methods are used, there are many problems as described below, and any of these methods needs to be improved. For example, (1) the coagulation separation / removal method cannot sufficiently treat zinc, (2) the adsorption removal method, etc., even if zinc can be adsorbed, a large amount of solid components are generated after the treatment, (3) reverse osmosis method In addition, electrodialysis or ultrafiltration is difficult to remove if organic substances are contained in the waste water, and the treatment cost is high. (4) The dry solidification method by heating evaporation is complicated and costly. Is high.

  By the way, the method (for example, refer patent documents 1-4) using the salt of dithiocarbamic acid as a heavy metal processing agent in waste_water | drain is proposed. However, no illustration is given regarding the treatment of zinc-containing wastewater containing a compound capable of complexing with zinc.

JP 2009-249399 A JP2011-074350A JP 2014-088477 A JP 2002-177902 A

  The objective of this invention is providing the purification method of the zinc containing aqueous solution which reduces the zinc density | concentration of the compound which has a complex formation capability with zinc, and the aqueous solution containing zinc to 2 mg / L or less.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors, as a result of using the novel purification method for zinc-containing aqueous solution shown in the present invention, contain a compound capable of complexing with zinc and zinc. It was found that the concentration of zinc can be reduced to 2 mg / L or less by a simple method, and the present invention has been completed.

That is, the present invention has the following gist.
[1] After adding a salt of dithiocarbamic acid and an inorganic flocculant more than the content of the compound capable of complexing with zinc to a compound having a complexing ability with zinc and an aqueous solution containing zinc, A method for purifying a zinc-containing aqueous solution, comprising removing the aqueous solution.
[2] The compound having the ability to complex with zinc is a compound having in the molecule at least one substituent selected from a carboxyl group, an amino group, a hydroxyl group, an ether group and a phosphate group. The method for purifying a zinc-containing aqueous solution according to the above [1].
[3] The dithiocarbamic acid salt is obtained by reacting an amine compound having a primary amino group and / or a secondary amino group, carbon disulfide and an alkali metal hydroxide. The method for purifying a zinc-containing aqueous solution according to the above [1] or [2].
[4] The method for purifying a zinc-containing aqueous solution according to any one of the above [1] to [3], wherein the inorganic flocculant is an iron compound and / or an aluminum compound.
[5] A zinc-containing aqueous solution characterized in that the aqueous solution treated by the purification method according to any one of [1] to [4] above is mixed with separately prepared water so that the zinc concentration is 2 mg / L or less. Purification method.

  Hereinafter, the present invention will be described in detail.

  The method for purifying a zinc-containing aqueous solution of the present invention is characterized in that after adding a dithiocarbamic acid salt and an inorganic flocculant to a zinc complex-containing compound and an aqueous solution containing zinc, the solid matter is removed. To do.

  The compound having the ability to form a complex with zinc is not particularly limited as long as it is a compound that forms a complex with zinc. For example, at least one selected from a carboxyl group, an amino group, a hydroxyl group, an ether group, and a phosphate group in the molecule. The compound which has the substituent of these is mentioned. In particular, EDTA is a compound that forms a strong complex with zinc.

  The zinc concentration in the zinc-containing aqueous solution is not particularly limited, but it is preferable to treat a zinc-containing aqueous solution having a concentration higher than 2 mg / L, which is a drainage standard.

  The salt of dithiocarbamic acid is not particularly limited as long as it is a compound having a dithiocarbamyl group in the molecule. For example, diethylamine, piperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and heptaethyleneoctamine And compounds obtained by reacting an amine compound having a primary amino group and / or a secondary amino group such as carbon disulfide and an alkali metal hydroxide.

  Among these, the compound obtained by making piperazine or tetraethylenepentamine, carbon disulfide, and an alkali metal hydroxide react is preferable at the point of the processing performance of zinc, and the stability of a compound. However, the salt of tetraethylenepentamine dithiocarbamic acid is a composition in which tetraethylenepentamine as a raw material includes analogs [chemical formulas (2) to (4)] in addition to the main component linear body [chemical formula (1)]. Since only the product is produced industrially, the resulting salt of dithiocarbamic acid is also a composition, and there is a drawback that it is complicated in quality control. On the other hand, the salt of piperazine dithiocarbamate does not have such disadvantages and is particularly preferable.

アルカリ金属水酸化物としては、入手が容易な点で、水酸化ナトリウムや水酸化カリウムが特に好ましい。

As the alkali metal hydroxide, sodium hydroxide or potassium hydroxide is particularly preferable because it is easily available.

  It is necessary to add an inorganic flocculant to quickly remove the solid matter. Moreover, it is preferable to use an inorganic compound and a polymer compound in combination as the flocculant. As the inorganic compound, a commercially available inorganic flocculant can be used, and examples thereof include ferric chloride, aluminum sulfate, and polyaluminum chloride.

  The inorganic flocculant is preferably added in an amount equal to or greater than the content of the compound capable of complexing with zinc. When the amount of the inorganic flocculant added is less than the content of the compound capable of complexing with zinc, the cohesiveness may be insufficient and the zinc concentration may not be reduced to 2 mg / L or less.

  The content of the compound capable of complexing with zinc can be calculated by analyzing the concentration of the compound capable of complexing with zinc in an aqueous solution containing zinc, such as HPLC, gas chromatography, and titration.

  As the polymer compound, a commercially available polymer flocculant can be used, and examples thereof include acrylic acid polymer, acrylamide polymer, and dimethylaminoethyl methacrylate polymer. A weak anionic acrylic acid polymer is preferred from the viewpoint of aggregation performance.

  The order of adding the dithiocarbamic acid salt and the inorganic flocculant is not particularly limited. For example, a method of adding the salt of dithiocarbamic acid first and then adding the inorganic flocculant, or adding the inorganic flocculant first. Next, a method of adding a salt of dithiocarbamic acid can be mentioned. In the method of adding the inorganic flocculant first, after adding the salt of dithiocarbamic acid, it may be necessary to add the inorganic flocculant again, so the salt of dithiocarbamic acid is added first, and then the inorganic flocculant The method of adding is preferable.

  The method for removing the solid material is not particularly limited, and examples thereof include filtration, centrifugation, and a method for separating the solid material from the supernatant after sedimentation.

  In this purification method, when the amount of the drug added is insufficient and the zinc concentration exceeds 2 mg / L, it may be mixed with separately prepared water to make the zinc concentration 2 mg / L or less.

  According to the present invention, the zinc concentration can be reduced to 2 mg / L or less even in the case of an aqueous solution containing zinc and a compound capable of complexing with zinc, which is difficult to treat zinc.

  The present invention will be specifically described below, but the present invention is not construed as being limited by these examples.

(Analysis method)
The zinc ion concentration in the aqueous solution was measured with an ICP emission spectroscopic analyzer (OPTIMA 3300 DV, manufactured by Perkin Elmaer).

Reference example 1
The chelating agent (dithiocarbamic acid salt) used in the Examples and Comparative Examples was prepared according to the following method.

(Preparation of salt A of dithiocarbamic acid)
After mixing 112 g of piperazine (manufactured by Tosoh Corporation) and 386 g of pure water, while stirring in a nitrogen stream at 25 ° C., 306 g of 48 wt% potassium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 196 g of carbon disulfide (manufactured by Kishida Chemical Co., Ltd.) ) Was divided into 4 parts and dropped alternately. The mixture was stirred for 1 hour to obtain an aqueous solution containing 40% by weight of the compound represented by the chemical formula (5).

（ジチオカルバミン酸の塩Ｂの調製）
テトラエチレンペンタミン（東ソー社製）１５９ｇと純水３３１ｇを混合した後、２５℃で、窒素気流中で攪拌しながら４８重量％水酸化ナトリウム２８１ｇ（キシダ化学社製）と二硫化炭素２３０ｇ（キシダ化学社製）をそれぞれ４分割して交互に滴下した。１時間攪拌し、化学式（６）に示す化合物４０重量％を含む水溶液を得た。

(Preparation of salt B of dithiocarbamic acid)
After mixing 159 g of tetraethylenepentamine (manufactured by Tosoh Corporation) and 331 g of pure water, 281 g of 48 wt% sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 230 g of carbon disulfide (Kishida Chemical) were stirred at 25 ° C. in a nitrogen stream. (Manufactured by Kagaku Co., Ltd.) was divided into four portions and dropped alternately. The mixture was stirred for 1 hour to obtain an aqueous solution containing 40% by weight of the compound represented by the chemical formula (6).

（無機凝集剤）
無機凝集剤として、３８重量％塩化第二鉄水溶液（キシダ化学社製）、２７重量％硫酸アルミニウム水溶液（キシダ化学社製）、及び３０重量％ポリ塩化アルミニウム水溶液（キシダ化学社製）を使用した。

(Inorganic flocculant)
As inorganic flocculants, 38 wt% ferric chloride aqueous solution (Kishida Chemical Co., Ltd.), 27 wt% aluminum sulfate aqueous solution (Kishida Chemical Co., Ltd.), and 30 wt% polyaluminum chloride aqueous solution (Kishida Chemical Co., Ltd.) were used. .

(Polymer flocculant)
OA-23 (weak anion polymer) manufactured by Organo Corporation was used as the polymer flocculant.

  As an example of a method for quantifying a compound capable of complexing with zinc, a method for quantifying EDTA in an aqueous solution containing zinc is shown as an example.

Reference example 2
200 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was prepared in a beaker, and trans-1,2-diaminocyclohexane-N, N, N ′, N′-tetraacetic acid (Dojin Chemical Co., Ltd.) was used as an internal standard substance (surrogate). After adding 25 μL of a laboratory solution (40 mg / L), the mixture was heated on a hot plate and concentrated by evaporation until the residual liquid reached about 2 mL. The remaining solution was transferred to a 10 mL centrifuge tube with a screw cap, and a small amount of washing solution was combined. To this concentrated solution, 200 μL of formic acid was added and mixed, and nitrogen gas was blown while heating to about 70 ° C. on a heat block to completely evaporate to dryness. Boron trifluoride-methanol (1 mL) was added to the residue in the centrifugal sedimentation tube and sealed, and heated to 80 ° C. on a heat block to conduct a derivatization reaction for 1 hour. After cooling, 3 mL of phosphate buffer and 2 mL of dichloromethane were added and shaken vigorously for 10 minutes, and then centrifuged at 3500 rpm for 15 minutes. The dichloromethane layer was taken and filtered using filter paper, and the filtrate was analyzed with a gas chromatograph-mass spectrometer.

  As a result of the analysis, the EDTA concentration was 260 mg / L, and it was confirmed by quantitative analysis that it was the same as the charged concentration.

Examples 1-6
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. While stirring at 150 rpm, add a predetermined amount of dithiocarbamic acid salt A or dithiocarbamic acid salt B, stir at 150 rpm for 10 minutes, then add a predetermined amount of 38 wt% aqueous ferric chloride solution, and stir at 150 rpm for 5 minutes. Next, a predetermined amount of 0.1 wt% OA-23 aqueous solution was added and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted to always be pH 7 using a trace amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

  The results are shown in Table 1 below.

この表１から明らかな様に、実施例１〜３では、処理後水溶液の亜鉛濃度は２ｍｇ／Ｌ以下であり、排水基準である２ｍｇ／Ｌを下回っており、亜鉛の処理が十分であった。

As is apparent from Table 1, in Examples 1 to 3, the zinc concentration of the aqueous solution after the treatment was 2 mg / L or less, which was lower than the wastewater standard of 2 mg / L, and the zinc treatment was sufficient. .

  Example 4 is an example in which the amount of dithiocarbamic acid salt A added in Example 1 was reduced, but the zinc concentration of the aqueous solution after the treatment was 2.2 mg / L, which was a slight effluent standard of 2.0 mg / L. L exceeded. Therefore, as a result of preparing an aqueous solution in which 100 mL of zinc-free water prepared separately from 500 mL of the aqueous solution after treatment was prepared and measuring the zinc concentration, the zinc concentration was 1.8 mg / L, which is the drainage standard 2 0.0 mg / L was met.

  Example 5 is an example in which the polymer flocculant (OA-23) of Example 1 was not added, but the zinc concentration of the aqueous solution after treatment was 1.9 mg / L, and the polymer flocculant was added. Even if not, 2.0 mg / L which is a wastewater standard was satisfied.

  Example 6 is an example in which the salt B of dithiocarbamic acid was used in place of the salt A of dithiocarbamic acid of Example 1, but the zinc concentration of the aqueous solution after treatment was 1.8 mg / L, which was 2 mg as a wastewater standard. / L, and the zinc treatment was sufficient.

Comparative Examples 1-3
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. While stirring at 150 rpm, a predetermined amount of 38 wt% ferric chloride aqueous solution was added and stirred at 150 rpm for 5 minutes, and then a predetermined amount of 0.1 wt% OA-23 aqueous solution was added and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was always adjusted to a predetermined pH value using a small amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

Comparative Examples 4-6
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. While stirring at 150 rpm, 1300 mg / L of dithiocarbamic acid salt A was added, stirred at 150 rpm for 10 minutes, then a predetermined amount of 38 wt% aqueous ferric chloride solution was added, stirred at 150 rpm for 5 minutes, and then 0 A predetermined amount of 1 wt% OA-23 aqueous solution was added and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted to always be pH 7 using a trace amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

  The results are shown in Table 2 below.

比較例１〜３は、鉄イオンを添加して中和し、亜鉛イオンを鉄イオンと共に水酸化物として沈殿させる従来の処理方法の例であるが、処理後水溶液の亜鉛濃度は４．３ｍｇ／Ｌ以上であり、排水基準である２ｍｇ／Ｌを超過しており、亜鉛の処理が不十分であった。

Comparative Examples 1 to 3 are examples of conventional treatment methods in which iron ions are added to neutralize and zinc ions are precipitated as hydroxides together with iron ions, but the zinc concentration of the aqueous solution after treatment is 4.3 mg / It was more than L and exceeded the wastewater standard of 2 mg / L, and the treatment of zinc was insufficient.

  Comparative Examples 4 to 6 are examples in which ferric chloride which is an inorganic flocculant was added in an amount smaller than the content of EDTA which is a compound capable of complexing with zinc, but the zinc concentration of the aqueous solution after treatment Was 5.0 mg / L or more, exceeding 2 mg / L which is the drainage standard, and the treatment of zinc was insufficient.

Examples 7-8
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of polyphosphoric acid or polyethylene glycol was added. While stirring at 150 rpm, a predetermined amount of dithiocarbamic acid salt A was added, stirred at 150 rpm for 10 minutes, then a predetermined amount of 38 wt% aqueous ferric chloride solution was added, stirred at 150 rpm for 5 minutes, and then 0.1%. A predetermined amount of a weight% OA-23 aqueous solution was added, and the mixture was stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted to always be pH 7 using a trace amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

Comparative Examples 7-9
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of polyphosphoric acid or polyethylene glycol was added. While stirring at 150 rpm, a predetermined amount of 38 wt% ferric chloride aqueous solution was added and stirred at 150 rpm for 5 minutes, and then a predetermined amount of 0.1 wt% OA-23 aqueous solution was added and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was always adjusted to a predetermined pH value using a small amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

  The results are shown in Table 3 below.

この表３から明らかな様に、実施例７〜８では、処理後水溶液の亜鉛濃度は２ｍｇ／Ｌ以下であり、排水基準である２ｍｇ／Ｌを下回っており、亜鉛の処理が十分であった。

As apparent from Table 3, in Examples 7 to 8, the zinc concentration of the aqueous solution after the treatment was 2 mg / L or less, which was lower than the wastewater standard of 2 mg / L, and the zinc treatment was sufficient. .

  Comparative Examples 7 to 9 are examples of conventional treatment methods in which iron ions are added to neutralize and zinc ions are precipitated together with iron ions as hydroxides, but the zinc concentration of the aqueous solution after treatment is 2.8 mg / It was more than L and exceeded the wastewater standard of 2 mg / L, and the treatment of zinc was insufficient.

Examples 9-10
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. While stirring at 150 rpm, a predetermined amount of dithiocarbamic acid salt A was added, stirred at 150 rpm for 10 minutes, then a predetermined amount of 27 wt% aluminum sulfate or 30 wt% polyaluminum chloride aqueous solution was added, and stirred at 150 rpm for 5 minutes, Next, a predetermined amount of 0.1 wt% OA-23 aqueous solution was added and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted to always be pH 7 using a trace amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

Comparative Examples 10-13
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. While stirring at 150 rpm, a predetermined amount of 27 wt% aluminum sulfate or 30 wt% polyaluminum chloride aqueous solution was added, stirred at 150 rpm for 5 minutes, and then 0.1 wt% OA-23 aqueous solution was added, Stir at 50 rpm for 5 minutes. The pH of the aqueous solution was always adjusted to a predetermined pH value using a small amount of hydrochloric acid and sodium hydroxide. After completion of stirring, the mixture was allowed to stand for 10 minutes, and the aqueous solution was filtered off with 5A filter paper manufactured by Advantech, and the zinc concentration of the aqueous solution after treatment was measured.

  The results are shown in Table 4 below.

実施例９〜１０は、実施例１〜５で用いた塩化第二鉄の代わりに硫酸アルミニウムやポリ塩化アルミニウムを無機凝集剤に用いた例であるが、処理後水溶液の亜鉛濃度は２ｍｇ／Ｌ以下であり、排水基準である２ｍｇ／Ｌを下回っており、亜鉛の処理が十分であった。

Examples 9 to 10 are examples in which aluminum sulfate or polyaluminum chloride was used as an inorganic flocculant instead of ferric chloride used in Examples 1 to 5, but the zinc concentration of the aqueous solution after treatment was 2 mg / L. This was below the 2 mg / L drainage standard, and the zinc treatment was sufficient.

  Comparative Examples 10 to 13 are examples of conventional treatment methods in which aluminum ions are added for neutralization and zinc ions are precipitated as hydroxides together with aluminum ions, but the zinc concentration of the aqueous solution after treatment is 5.0 mg / It was more than L and exceeded the wastewater standard of 2 mg / L, and the treatment of zinc was insufficient.

  According to the method for purifying a zinc-containing aqueous solution of the present invention, the zinc concentration can be reduced to 2 mg / L or less even for a compound that is difficult to treat zinc and that has a complexing ability with zinc and an aqueous solution containing zinc. As a novel purification method for zinc-containing aqueous solutions, it has the potential to be used as a treatment method for zinc-containing wastewater from plating factories, electronic component / mechanical component manufacturing factories, automobile factories, and the like.

Claims (5)

After adding a salt of dithiocarbamic acid and an inorganic flocculant in excess of the content of the compound capable of complexing with zinc to a compound capable of complexing with zinc and an aqueous solution containing zinc, the solid matter should be removed. A method for purifying a zinc-containing aqueous solution. 2. The compound having the ability to form a complex with zinc is a compound having at least one substituent selected from a carboxyl group, an amino group, a hydroxyl group, an ether group and a phosphate group in the molecule. A method for purifying a zinc-containing aqueous solution according to claim 1. The salt of dithiocarbamic acid is obtained by reacting an amine compound having a primary amino group and / or a secondary amino group, carbon disulfide and an alkali metal hydroxide. Or the purification method of the zinc-containing aqueous solution of 2. The method for purifying a zinc-containing aqueous solution according to any one of claims 1 to 3, wherein the inorganic flocculant is an iron compound and / or an aluminum compound. A method for purifying a zinc-containing aqueous solution, wherein the aqueous solution treated by the purification method according to any one of claims 1 to 4 is mixed with separately prepared water so that the zinc concentration is 2 mg / L or less.