JP7183560B2 - Purifying Agent for Nickel-Containing Aqueous Solution and Method for Purifying Nickel-Containing Aqueous Solution - Google Patents

Description

The present invention relates to a compound capable of complexing with nickel and to a purification method that makes it possible to remove nickel from aqueous solutions containing nickel.

An aqueous solution containing nickel is sent to a wastewater treatment facility, for example, iron ions are added to make it alkaline, nickel ions and the like are precipitated as hydroxide together with iron ions and other ions contained, and the aqueous solution is treated. A method of releasing after separation has been practiced.

Nickel is a hazardous heavy metal designated as a Class 1 Designated Chemical Substance under the Chemical Substance Emission Control Promotion Law, and is set as a monitoring item in environmental standards related to water pollution, increasing the importance of wastewater treatment. ing.

By the way, wastewater from plating factories, electronic parts and machine parts manufacturing factories, automobile factories, thermal power plants, waste incineration plants, etc. contains organic acids such as citric acid and gluconic acid, and ethylenediaminetetraacetic acid (hereinafter abbreviated as EDTA). , cyanide, amines, ammonia, and polyphosphoric acid, which have the ability to form complexes with nickel, and there are many cases in which the above-mentioned hydroxide method cannot be used for treatment.

On the other hand, a method is known in which nickel is chemically treated with a compound capable of forming a complex with nickel, and then nickel is insolubilized. However, even if a chemical treatment such as an oxidation method using a chlorine-based chemical, an electrolytic oxidation method, a hydrogen peroxide-ferrous salt method, an ozone oxidation method, or a wet oxidation method is used, the oxidation reaction due to the coexisting heavy metal elements does not occur. Due to problems such as inhibition and scale formation, it is not possible to carry out sufficient purification treatment.

Techniques for removing various heavy metal elements contained in wastewater include, for example, a coagulation separation removal method by adding an inorganic coagulant or an organic coagulant, a removal method by electrolysis, adsorption by activated carbon, an inorganic adsorbent, or an organic polymer material. A removal method, a drying method in which waste water is heated and evaporated, a reverse osmosis method using a membrane, an electrodialysis method, an ultrafiltration method, and the like have been proposed.

Even when the various methods described above are used, there are many problems as described below, and there is a need for improvement in each method. for example,
(1) Nickel cannot be sufficiently treated by the flocculation and separation removal method,
(2) Adsorption and removal methods generate a large amount of solid components after treatment, even if nickel can be adsorbed.
(3) Reverse osmosis, electrodialysis, ultrafiltration, etc. are difficult to remove if organic matter is contained in the waste water, and the treatment cost is high.
(4) The drying method by heating evaporation is complicated and the processing cost is high.
etc.

By the way, methods of using inorganic sulfides as agents for treating heavy metals in wastewater have been proposed (see, for example, Patent Documents 1 to 5). However, the methods described in these patent documents are not sufficiently effective in purifying heavy metals from nickel-containing waste water containing compounds capable of forming complexes with heavy metals.

Japanese Patent Application Laid-Open No. 2017-160496 Japanese Patent No. 5877588 Japanese Unexamined Patent Application Publication No. 2014-235130 Japanese Patent No. 5138737 Japanese Patent No. 3243261

An object of the present invention is to provide a compound capable of forming a complex with nickel and a method for purifying an aqueous nickel-containing solution that reduces the nickel concentration of the aqueous solution containing nickel.

As a result of extensive studies to solve the above problems, the present inventors have found that, by using the novel method for purifying a nickel-containing aqueous solution shown in the present invention, a compound capable of forming a complex with nickel and a nickel-containing The present inventors have found that the concentration of nickel can be reduced by a simple method using an aqueous solution that dissolves, and have completed the present invention.

That is, the present invention has the following gists.

[1] A cleaning agent for a nickel-containing aqueous solution, comprising 100 parts by weight of an inorganic sulfide, 20 parts by weight or more of a polyamine having 3 to 8 nitrogen atoms, and an alkaline earth metal compound.

[2] A method for purifying a nickel-containing aqueous solution, which comprises adding the nickel-containing aqueous solution purifying agent according to [1] to the nickel-containing aqueous solution, and then removing the produced solid matter.

[3] The method for purifying a nickel-containing aqueous solution according to [2] above, wherein the nickel-containing aqueous solution further contains a compound capable of forming a complex with nickel.

[4] The nickel-containing aqueous solution according to [3] above, wherein the compound having the ability to form a complex with nickel is a compound having a functional group selected from the group consisting of a carboxyl group and an amino group in the molecule. purification method.

[5] The method for purifying a nickel-containing aqueous solution according to any one of [2] to [4] above, wherein an inorganic flocculant is added before removing the solid matter.

[6] The method for purifying a nickel-containing aqueous solution according to any one of [2] to [4] above, wherein an inorganic flocculant and a polymer flocculant are added before removing solid matter.

[7] The method for purifying a nickel-containing aqueous solution according to [5] or [6] above, wherein the inorganic flocculant is selected from the group consisting of iron compounds and aluminum compounds.

The present invention will be described in detail below.

The cleaning agent for a nickel-containing aqueous solution of the present invention is characterized by comprising 20 parts by weight or more of a polyamine having 3 to 8 nitrogen atoms and an alkaline earth metal compound per 100 parts by weight of an inorganic sulfide.

Examples of sulfide salts include sodium sulfide, sodium hydrogen sulfide, potassium sulfide, potassium hydrogen sulfide, calcium sulfide, calcium hydrogen sulfide, magnesium hydrogen sulfide, and ammonium sulfide. Of these, sodium hydrogen sulfide is preferred from the point of view of economy.

Examples of polyamines having 3 to 8 nitrogen atoms include polyethyleneimines having a weight-average molecular weight of 300 or less, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and heptaethyleneoctamine. is particularly preferred.

The amount of the polyamine having 3 to 8 nitrogen atoms to be added to 100 parts by weight of the inorganic sulfide is preferably 20 parts by weight or more, and by adding 100 parts by weight or more, a sufficient nickel treating capacity can be obtained.

Examples of alkaline earth metal compounds include beryllium fluoride, beryllium chloride, beryllium bromide, beryllium iodide, beryllium oxide, beryllium hydroxide, beryllium carbonate, beryllium nitrate, beryllium sulfate, beryllium sulfide, calcium fluoride, and calcium chloride. , calcium bromide, calcium iodide, calcium oxide, calcium hydroxide, calcium carbonate, calcium hydrogen carbonate, calcium nitrate, calcium sulfate, calcium sulfide, calcium phosphate, calcium acetate, calcium oxalate, magnesium chloride, magnesium bromide, iodide magnesium, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium hydrogen carbonate, magnesium nitrate, magnesium sulfate, magnesium sulfide, magnesium phosphate, magnesium acetate, strontium fluoride, strontium chloride, strontium bromide, strontium iodide, strontium oxide, Strontium hydroxide, strontium carbonate, strontium nitrate, strontium sulfate, strontium sulfide, strontium phosphate, strontium acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium hydroxide, barium carbonate, barium nitrate, barium sulfate, Barium sulfide, barium phosphate, barium acetate, radium chloride, radium bromide and the like.

If the alkaline earth metal compound is added in an amount of 0.05 g/L or more, the nickel processing capacity can be obtained. However, even if 5 g/L or more is added, the nickel processing capacity remains constant, so the amount of the alkaline earth metal compound added should be increased. This means that nickel wastewater treatment costs are high, which is not economical.

The cleaning agent of the present invention is particularly useful for cleaning nickel-containing aqueous solutions.

The method for purifying a nickel-containing aqueous solution of the present invention is characterized by adding the above-described purifying agent of the present invention to the nickel-containing aqueous solution, and then removing the produced solid matter. Here, the produced solid contains nickel immobilized by the cleaning agent of the present invention.

The purification method of the present invention is particularly effective for nickel-containing aqueous solutions in which nickel is difficult to treat (for example, compounds capable of complexing with nickel) and nickel-containing aqueous solutions.

The compound capable of forming a complex with nickel is not particularly limited as long as it is a compound that forms a complex with nickel. Examples thereof include compounds having a functional group selected from the group consisting of a carboxyl group and an amino group in the molecule. Specific examples thereof include EDTA and polyphosphoric acid, and particularly, EDTA is an example of a compound that forms a strong complex with nickel.

When the inorganic sulfide, the polyamine having 3 to 8 nitrogen atoms, and the alkaline earth metal compound are separately added to the nickel-containing aqueous solution, the order of addition is not particularly limited.

In order to remove the solids quickly, it is preferable to add a flocculant before removing the solids. Examples of the flocculant include inorganic flocculants and polymer flocculants, and it is more preferable to use an inorganic flocculant and a polymer flocculant in combination.

Commercially available inorganic flocculants can be used as the inorganic flocculant, and there is no particular limitation. Examples thereof include iron compounds such as ferric chloride, and aluminum compounds such as aluminum sulfate and polyaluminum chloride.

When the nickel-containing aqueous solution contains a compound capable of forming a complex with nickel, the amount of the inorganic flocculant added is preferably equal to or greater than the content of the compound capable of forming a nickel complex contained in the nickel-containing aqueous solution. By setting the amount of the inorganic flocculant added to be equal to or greater than the content of the compound capable of forming a complex with nickel, the aggregating property is increased, and the nickel concentration in the aqueous solution after treatment can be easily reduced.

The content of the compound capable of forming a complex with nickel in the nickel-containing aqueous solution is obtained by analyzing the concentration of the compound capable of forming a nickel complex in the nickel-containing aqueous solution by, for example, HPLC, gas chromatography, titration, etc. can be calculated by

Commercially available polymer flocculants can be used as the polymer flocculant, and are not particularly limited. Examples include acrylic acid polymer, acrylamide polymer, dimethylaminoethyl methacrylate polymer, and the like. A weakly anionic acrylic acid polymer is preferred in terms of flocculation performance. Adding a polymer flocculant before removing the solids may facilitate handling of the removed solids.

When an inorganic flocculant and a polymer flocculant are used together, the order of adding these flocculants is not particularly limited, but it is preferable to add the inorganic flocculant and then add the polymer flocculant.

The method for removing the solid matter is not particularly limited, and examples thereof include filtration, centrifugation, and a method of sedimenting the solid matter and then separating it from the supernatant.

The cleaning agent for nickel aqueous solution of the present invention can reduce the nickel concentration even in a nickel-containing aqueous solution that is difficult to purify nickel (for example, a compound having the ability to form a complex with nickel and an aqueous solution containing nickel). can be done.

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

(analysis method)
The nickel ion concentration in the aqueous solution was measured with an ICP emission spectrometer (ICPE-9800, manufactured by Shimadzu Corporation).

(Inorganic sulfide)
Sodium hydrogen sulfide manufactured by Kishida Chemical Co., Ltd. was used as the inorganic sulfide.

(polyamine)
As polyamines, the following ethyleneamines manufactured by Tosoh and polyethyleneimines manufactured by Nippon Shokubai Co., Ltd. were used.

ethylenediamine (hereinafter abbreviated as EA(2));

diethylenetriamine (hereinafter abbreviated as EA(3));

Polyethyleneimine with a weight average molecular weight of 1800 (hereinafter abbreviated as PEI (1800)).

(alkaline earth metal)
Calcium chloride manufactured by Kishida Chemical Co., Ltd. was used as the alkaline earth metal.

(Inorganic flocculant)
The following aqueous solutions were used as inorganic flocculants.

30 g of polyaluminum chloride manufactured by Kishida Chemical Co., Ltd. was added to water to make a total of 100 g aqueous solution (30% by weight polyaluminum chloride aqueous solution).

38% by weight ferric chloride aqueous solution manufactured by Kishida Chemical Co., Ltd.;

(Polymer flocculant)
As a polymer flocculant, OA-23 (weak anionic polymer) manufactured by Organo Co., Ltd. was used.

Example 1
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg/L of nickel ions and 25 mg/L of EDTA was added. Then, while stirring at 150 rpm, 200 mg/L of sodium hydrogen sulfide, 200 mg/L of diethylenetriamine (EA(3)) and 1 g/L of calcium chloride were added, the pH was adjusted to 11, and the mixture was stirred at 150 rpm for 1 hour. Then, 1000 mg/L of a 30% by weight polyaluminum chloride (hereinafter abbreviated as PAC) aqueous solution was added, the pH was adjusted to 7, and the mixture was stirred at 150 rpm for 5 minutes. The pH of the aqueous solution was adjusted so as to always have a predetermined pH using a minute amount of hydrochloric acid and sodium hydroxide. After stirring, the mixture was allowed to stand still for 10 minutes, and the aqueous solution was filtered through Advantech 5A filter paper, and the nickel concentration of the treated aqueous solution was measured.

Comparative example 1
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg/L of nickel ions and 25 mg/L of EDTA was added. The pH was then adjusted to 11 and stirred at 150 rpm for 1 hour. Then, 1000 mg/L of 30% by weight PAC aqueous solution was added to adjust the pH to 7, and the mixture was stirred at 150 rpm for 5 minutes. The pH of the aqueous solution was adjusted so as to always have a predetermined pH using a minute amount of hydrochloric acid and sodium hydroxide. After stirring, the mixture was allowed to stand still for 10 minutes, and the aqueous solution was filtered through Advantech 5A filter paper, and the nickel concentration of the treated aqueous solution was measured.

Comparative Examples 2-9
The nickel concentration of the aqueous solution after the treatment was measured in the same manner as in Comparative Example 1, except that the chemicals to be added were changed to those shown in Table 1. These results are also shown in Table 1.

Example 1 was able to reduce the nickel concentration of the post-treatment aqueous solution of EDTA-containing waste water to 1.5 mg/L, and was able to treat nickel.

Comparative Example 1 is an example of a treatment method in which aluminum ions are added for neutralization, and nickel ions are precipitated as hydroxide together with aluminum ions. The nickel concentration of the aqueous solution after treatment was 7.0 mg/L, and nickel could not be reduced.

Comparative Example 2 is an example in which only calcium chloride was added for treatment. The nickel concentration of the aqueous solution after treatment was 5.3 mg/L, and nickel could not be reduced.

Comparative Example 3 is an example in which only sodium hydrogen sulfide was added for treatment. The nickel concentration of the aqueous solution after treatment was 7.0 mg/L, and nickel could not be sufficiently reduced.

Comparative Example 4 is an example treated by adding sodium hydrogen sulfide and calcium chloride. The nickel concentration of the aqueous solution after treatment was 5.5 mg/L, and nickel could not be reduced.

Comparative Example 5 is an example in which only polyamine was added for treatment. The nickel concentration in the aqueous solution after treatment was 10 mg/L, the same value as before the addition of the chemical, and nickel could not be reduced.

Comparative Example 6 is an example treated by adding polyamine and calcium chloride. The nickel concentration in the aqueous solution after treatment was 10 mg/L, the same value as before the addition of the chemical, and nickel could not be reduced.

Comparative Example 7 is an example treated by adding sodium hydrogen sulfide and polyamine. The nickel concentration of the aqueous solution after treatment was 6.4 mg/L, and nickel could not be sufficiently reduced.

Comparative Example 8 is an example in which sodium hydrogen sulfide, EA (2), which is outside the scope of the present invention, and calcium chloride were added for treatment. Compared with Comparative Example 4, no improvement effect was observed in the treatment of nickel.

Comparative Example 9 is an example in which sodium hydrogen sulfide, PEI (1800) outside the scope of the present invention, and calcium chloride were added for treatment. could not be reduced.

Examples 2-3, Comparative Example 10
The nickel concentration of the aqueous solution after treatment was measured in the same manner as in Example 1, except that the chemicals to be added were changed to those shown in Table 2. These results are also shown in Table 2.

Examples 2 and 3 are examples in which the parts by weight of the polyamine were varied within the scope of the present invention. Regardless of the weight part of the polyamine, the concentration of nickel could be reduced to 2.7 mg/L or less, and the nickel could be treated.

Comparative Example 10 is an example in which sodium hydrogen sulfide and an amount of polyamine below the range of the present invention were added, but a sufficient effect of reducing nickel was not observed.

Example 4
A jar tester was installed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg/L of nickel ions and 25 mg/L of EDTA was added. Then, while stirring at 150 rpm, 200 mg/L of sodium hydrogen sulfide, 200 mg/L of diethylenetriamine (EA(3)) and 1 g/L of calcium chloride were added to adjust the pH to 11 and stirred at 150 rpm for 1 hour. Then, 1000 mg/L of 30% by weight PAC aqueous solution was added to adjust the pH to 7, and the mixture was stirred at 150 rpm for 5 minutes. Then, 2000 mg/L of 0.1% by weight OA-23 aqueous solution was added as a polymer flocculant, the pH was adjusted to 7, and the mixture was stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted so as to always have a predetermined pH using a minute amount of hydrochloric acid and sodium hydroxide. After stirring, the mixture was allowed to stand still for 10 minutes, and the aqueous solution was filtered through Advantech 5A filter paper, and the nickel concentration of the treated aqueous solution was measured. Table 3 shows the results.

Example 5
The nickel concentration of the treated aqueous solution was measured in the same manner as in Example 4, except that the 30% by weight PAC aqueous solution was changed to a 38% by weight iron chloride aqueous solution. Table 3 shows the results.

Example 4 is an example in which a polymer flocculant is added to Example 1. The nickel concentration of the aqueous solution after the treatment was the same as when no polymer flocculant was added, indicating sufficient nickel treatment.

Example 5 is an example using an aqueous ferric chloride solution as an inorganic flocculant. The nickel concentration of the aqueous solution after the treatment was 1.7 mg/L, and the nickel treatment was sufficient regardless of the type of inorganic coagulant.

According to the method for purifying a nickel-containing aqueous solution of the present invention, it is possible to reduce the nickel concentration even in an aqueous solution containing a compound having the ability to form a complex with nickel, which is difficult to treat nickel, and nickel. As a method for purifying an aqueous solution, it has the potential to be used as a method for treating nickel-containing wastewater from plating factories, electronic and mechanical parts manufacturing factories, automobile factories, and the like.

Claims (7)

A cleaning agent for a nickel-containing aqueous solution , comprising 20 to 200 parts by weight of diethylenetriamine and 25 to 2500 parts by weight of calcium chloride with respect to 100 parts by weight of sodium hydrogen sulfide. A method for purifying a nickel-containing aqueous solution, which comprises adding the nickel-containing aqueous solution purifying agent according to claim 1 to the nickel-containing aqueous solution, and then removing the produced solid matter. 3. The method for purifying a nickel-containing aqueous solution according to claim 2, wherein the nickel-containing aqueous solution further contains a compound capable of forming a complex with nickel. 4. The method for purifying a nickel-containing aqueous solution according to claim 3, wherein the compound capable of forming a complex with nickel is a compound having in its molecule a functional group selected from the group consisting of a carboxyl group and an amino group. The method for purifying a nickel-containing aqueous solution according to any one of claims 2 to 4, characterized in that an inorganic flocculant is added before removing the solid matter. The method for purifying a nickel-containing aqueous solution according to any one of claims 2 to 4, characterized in that an inorganic flocculant and a polymer flocculant are added before removing the solid matter. 7. The method for purifying a nickel-containing aqueous solution according to claim 5 or 6, wherein the inorganic flocculant is selected from the group consisting of iron compounds and aluminum compounds.