JP2002188078A - Metal scavenger and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal scavenger having excellent activities for scavenging lead, zinc or the like, and excellent scavenging activities in an acidic condition and capable of reducing the metal concentration remaining in a waste water or a waste gas, and the metal concentration eluted from a solid waste, and further to provide a method for producing the scavenger. SOLUTION: This metal scavenger contains at least one of a dithio acid group and a salt of the dithio acid group as a metal-scavenging functional group bonded to the nitrogen atom of a secondary amino group of the amino compound formed by condensing amines having at least one primary amino group, with aldehydes, and having no primary amino group and at least one secondary amino group. The method for producing the metal scavenger comprises reacting the amino compound having the secondary amino group with carbon disulfide to introduce the metal-scavenging functional group by substituting the active hydrogen bonded to the nitrogen atom of the secondary amino group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to wastewater and incinerated ash,
Immobilize metals present in solid waste such as dust, slag, sludge, soil, shredder dust, and collect and remove metals in waste gas to detoxify wastewater, solid waste, and waste gas. And a method for producing the same.

[0002]

2. Description of the Related Art Wastewater discharged from factories and research facilities, incinerated ash and dust generated in garbage incineration plants, slag discharged from mines, activated sludge used in wastewater treatment, contaminated soil, etc. Various metals are contained in solid waste or waste gas such as smoke emitted from a garbage incineration plant, and heavy metals harmful to the human body such as mercury, cadmium, lead, zinc, copper, and chromium are contained. May be present in large amounts.
Pollution of groundwater, rivers and seawater by metals eluted from solid wastes containing metals, and air pollution by waste gases containing metals have also become major social problems.

[0003] For this reason, conventionally, wastewater, solid waste,
It has been proposed to treat with a metal scavenger before releasing or discarding waste gas. As the metal scavenger, a dithiocarbamic acid-type metal scavenger with excellent ability to collect mercury, cadmium, etc. Is widely used. As such a dithiocarbamic acid-type metal collector, compounds obtained by reacting carbon disulfide with amines and introducing a dithioic acid group or a salt thereof into a nitrogen atom of an amino group of the amines are widely known.

[0004]

However, conventional dithiocarbamic acid-type metal scavengers have a good ability to collect metals such as mercury and cadmium, but have a low ability to collect metals such as lead and zinc. When these were included, it was difficult to perform sufficient treatment. Further, the metal in the solid waste is fixed by the metal trapping agent and is treated so as not to be eluted from the solid waste, and the solid waste treated with the metal trapping agent is used as it is. After being hardened with concrete, it is finally disposed. However, dithiocarbamic acid-type metal scavengers that have been widely used in the past have a weak binding force to metals under acidic conditions, and therefore, when the solid waste after treatment is exposed to acid rain or the like,
There is a risk that the bond between the metal collecting agent and the metal may be released, and the metal may be eluted from the solid waste to cause environmental pollution. In addition, the concentration of residual metals in wastewater and waste gas after treatment with a metal scavenger,
The metal concentration eluted from the solid waste after treatment with the metal scavenger is more preferable if it can be further reduced from the current standard value, but the conventional dithiocarbamic acid type obtained by reacting amines with carbon disulfide Even if the addition amount is further increased, the concentration of the residual metal in the wastewater or the waste gas cannot be reduced in proportion to the addition amount of the metal collection agent,
The concentration of the metal eluted from the solid waste could not be reduced in proportion to the amount of the metal scavenger added, and it was difficult to treat the waste more safely than before.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an excellent binding force to metals such as lead and zinc as well as a trapping force for metals such as mercury and cadmium.
In addition, it has a strong binding force to metals even under acidic conditions, and has a higher metal-collecting power than conventional dithiocarbamic acid-type metal collectors and metal dithiocarbamic acid-type metal collectors. It is an object of the present invention to provide an excellent metal collecting agent which can further reduce the concentration of residual metal and the concentration of metal eluted from solid waste.
Another object of the present invention is to provide a method for producing a dithiocarbamic acid-type metal trapping agent having excellent metal trapping power.

[0006]

That is, the metal collecting agent of the present invention has no primary amino group formed by condensation of an amine having at least one primary amino group with an aldehyde. And a dithioic acid group or a dithioic acid group as a metal-trapping functional group introduced by substituting an active hydrogen bonded to a nitrogen atom of a secondary amino group of an amino compound having at least one secondary amino group. It has at least one of a salt. Further, the method for producing a metal collecting agent of the present invention comprises the step of polycondensing an amine having at least one primary amino group and an aldehyde to form at least one secondary amino group having no primary amino group. An amino compound having an amino group is obtained, and then the amino compound is reacted with carbon disulfide to form a dithioacid group or a dithioacid group as a metal-trapping functional group bonded to the nitrogen atom of the secondary amino group of the amino compound. Characterized by introducing at least one of the following salts:

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The metal scavenger of the present invention is obtained by condensing an amine having at least one primary amino group with an aldehyde and then reacting the polycondensate with an alkali in the presence or absence of an alkali. And by reacting carbon disulfide.

Examples of the amines having at least one primary amino group include monoalkylamines such as monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine and monoisobutylamine; ethylenediamine, propylenediamine , Butylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine, pentaethylenehexamine, imino Aliphatic amines such as bispropylamine, monomethylaminopropylamine and methyliminobispropylamine; phenylenediamine Down, o-, m-, p-xylylenediamine, 3,5-diamino aromatic amines such as chlorobenzene; 1,3-bis cycloalkane polyamines such as (aminomethyl) cyclohexane; polyvinylamine,
Examples include polymers of unsaturated amines such as polyallylamine. In addition, unsaturated amines such as vinylamine and allylamine, and unsaturated amines that can be copolymerized with unsaturated amines such as dimethylacrylamide, styrene, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene sulfonic acid, and salts thereof. Copolymers with other monomers having a saturated bond are also included.

The aldehydes condensed with the above amines include, for example, formaldehyde, glutaraldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde and the like.

The amines and aldehydes need to be condensed so that no primary amino group of the amine remains and at least one secondary amino group remains. An amine having at least one primary amino group and an aldehyde are condensed to form an amino compound having no primary amino group and having at least one secondary amino group. The reaction is carried out at １５０150 ° C. for 0.5 to 10 hours. Further, it can be obtained by performing dehydration or the like as necessary. For each primary amino group,
0.5 molecular equivalents of aldehydes are preferred. When a primary amino group remains in an amino compound obtained by condensing an amine having a primary amino group with an aldehyde, a reactive metal trapping agent obtained by reacting carbon disulfide with the amino compound The content of impurities in the inside increases. In addition, if a secondary amino group is not present in an amino compound obtained by condensing an amine having a primary amino group with an aldehyde, the compound is reacted with carbon disulfide to form a dithioacid group or a salt of a dithioacid group. Can not be introduced.

By reacting an amino compound having no primary amino group and having at least one secondary amino group with carbon disulfide, the metal compound bound to the nitrogen atom of the secondary amino group can be collected. A dithioacid group can be introduced as a functional group of the above, and by carrying out this reaction in the presence of an alkali, a salt of the dithioacid group can be introduced. Examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, ammonia and the like. An amino compound having no primary amino group and having at least one secondary amino group and carbon disulfide are present in an amount of 0.2 carbon disulfide per secondary amino group in the presence or absence of an alkali.反 応 1.0 molecular equivalent reaction.
The reaction temperature is 10 to 60 ° C, and the reaction time is 0.5 to 20 hours, preferably 10 to 40 ° C and 1 to 10 hours.

Examples of the waste to be treated by the metal collecting agent of the present invention include wastewater and solid waste such as incinerated ash, dust, slag, sludge, soil, and shredder dust generated in a garbage incineration plant. Waste gas generated when garbage is incinerated in a garbage incineration plant is exemplified.

When treating wastewater, the metal-collecting agent of the present invention is added to the wastewater to be treated as it is or in a state of being dissolved or dispersed in water. A method of removing precipitated floc by precipitation is employed.
When treating solid waste such as collected incineration ash, dust, slag, sludge, soil, shredder dust, etc., the metal collecting agent of the present invention is added to these wastes in liquid or powder form. For example, a method of adding, spraying and kneading as an aqueous solution or dispersion, or kneading is adopted, whereby the metal in the solid waste reacts with the metal collecting agent of the present invention and is fixed. In the case of dust and waste gas, during the incineration process in an incinerator, for example, by spraying a solution of the metal-collecting agent of the present invention on the flue, etc. For example, a method of collecting soot and dust with a bag filter can be adopted. When the metal collecting agent of the present invention is supplied to the flue where waste gas and dust are present by spraying or the like, the metal contained in the waste gas (mainly a metal which is easily gasified such as mercury) is collected. And separate from the waste gas, and fix the metal contained in the dust.

When treating the waste water, solid waste, waste gas and the like with the metal collecting agent of the present invention, a conventional metal collecting agent may be used in combination within a range not to impair the intended purpose of the present invention. Is also good. The amount of the metal collecting agent varies depending on the amount of the metal contained in the solid waste or the like, but generally, the amount of the metal collecting agent of the present invention is 0.5 to 100 in the case of wastewater.
mg / l, preferably 0.1 to 50% by weight for solid waste, and about 0.5 to 2000 mg / Nm ^{3 for} waste gas.

The wastewater treated with the metal trapping agent of the present invention can be discharged to a river after separating and removing flocs. Solid waste such as incineration ash, dust, slag, soil, shredder dust, and sludge, and waste such as dust after waste gas treatment are solidified and discarded as necessary. Final disposal such as can be performed. When the waste treated with the metal trapping agent of the present invention is solidified with cement or the like and finally disposed of, even if the amount of cement used is small compared to the case where the waste is treated with the conventional metal trapping agent, the waste There is little fear that the metal is re-eluted to cause secondary contamination.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. The metal scavengers used in the following examples and comparative examples are as follows.

Metal collecting agent 1 (product of the present invention): 1.0 mol of monoethylamine and 0.5 of tetraethylenepentamine
An amino compound obtained by dropping 1.0 mol of phthalaldehyde at 50 ° C. for 7 hours to the mixture of the above and then dehydrating under reduced pressure to obtain an amino compound (the ratio of secondary amino groups is 7 per molecule) A compound obtained by reacting 5.0 moles of carbon disulfide with one molecule in the presence of sodium hydroxide (the number of dithioic acid groups per molecule is 5.0,
The remaining amount of secondary amino groups is 2).

Metal collecting agent 2 (product of the present invention): 1 mol of glutaraldehyde per 1 mol of dipropylenetriamine
After dropping at 30 ° C. for 3 hours, the mixture was dehydrated under reduced pressure, and reacted by dehydration under reduced pressure. A compound obtained by reacting 0 mol in the presence of potassium hydroxide (the number of dithioic acid groups per unit is 2.0, and the remaining amount of secondary amino groups is 1.0). 1 above
The unit is a single repeating structure of an amino compound having a repeating structure obtained from amines and aldehydes.

Metal collecting agent 3 (product of the present invention): 0.5 mol of p-xylylenediamine and 0.5 mol of triethylenetetramine
To a 5 mol mixture, 1.0 mol of formaldehyde was added dropwise at 70 ° C. for 6 hours, followed by dehydration under reduced pressure to obtain an amino compound (the ratio of secondary amino groups was 6 mol / unit). .0) per unit
Compound obtained by reacting 5.0 moles of carbon disulfide in the presence of sodium hydroxide (the number of dithioic acid groups per unit is 5.0, the remaining amount of secondary amino groups is 1.0) .

Metal collecting agent 4 (product of the present invention): glutaraldehyde 1.0 per mole of tetraethylenepentamine
Mol was added dropwise at 50 ° C. for 4 hours, and then dehydrated under reduced pressure to react. One unit of an amino compound (the ratio of secondary amino groups was 5.0 per unit) was added to carbon disulfide. A compound obtained by reacting 3.0 moles in the presence of sodium hydroxide (the number of dithioic acid groups per unit is 3.0, and the remaining amount of secondary amino groups is 2.0).

Metal collecting agent 5 (product of the present invention): An amino compound obtained by dropping 1.0 mol of isophthalaldehyde per 90 mol of diethylenetriamine at 90 ° C. for 3 hours and then dehydrating under reduced pressure to react. A compound obtained by reacting 2.5 mol of carbon disulfide with 1 unit in the presence of potassium hydroxide (the ratio of dithioic acid groups per unit is 3.0). Is 2.5, and the remaining amount of secondary amino groups is 0.5).

Metal collecting agent 6 (conventional product): 2 moles of carbon disulfide per mole of ethylenediamine were reacted in the presence of sodium hydroxide to introduce two sodium salts of dithioic acid groups into the nitrogen atom of ethylenediamine. Compound.

Examples 1-3, Comparative Example 1 830 mg / kg of zinc, 1460 mg / kg of lead, 4 mercury
Table 1 for 100 g of dust containing 70 mg / kg
An aqueous solution (or dispersion) of the metal collecting agent shown in (1) is added so that the addition amount of the metal collecting agent becomes 4 g (in terms of solid content),
The mixture was kneaded at 50 to 80 ° C for 20 minutes. 50 g of each of the dust treated and the untreated dust treated with each trapping agent were subjected to pH = 6.0 and pH =
The mixture was shaken in 500 ml of 3.5 water at room temperature for 6 hours, and the concentration of the metal eluted in the water was measured. The concentration of the metal eluted in the water was measured by atomic absorption spectrometry. Table 1 shows the results.

[0024]

[Table 1]

Examples 4 to 6, Comparative Example 2 An aqueous solution (or dispersion) of a metal collector shown in Table 2 per 100 g of slag containing 520 mg / kg of lead, 1,730 mg / kg of zinc, and 180 mg / kg of cadmium. Is added so that the added amount becomes 3.5 g (in terms of solid content),
The mixture was kneaded at 80 to 120 ° C for 10 minutes. Using 50 g of each of the slag treated and the untreated slag with each collector, the metal concentration eluted in water was measured in the same manner as in Examples 1 to 3. Table 2 shows the results.

[0026]

[Table 2]

Examples 7 to 9, Comparative Example 3 28 mg / kg of lead, 11 mg / kg of mercury, 5 cadmium
For 100 g of soil containing 22 mg / kg,
An aqueous solution (or dispersion) of the metal collecting agent shown in Table 3 was added so that the addition amount became 2 g (in terms of solid content), and 100 to 1
Kneaded at 50 ° C. for 30 minutes. Using 50 g of each of soil treated with each collector and untreated soil, the metal concentration eluted in water was measured in the same manner as in Examples 1 to 3. Table 3 shows the results.

[0028]

[Table 3]

[0029] Examples 10 to 12, Comparative Example 4 mercury 2mg / Nm ^3, lead 5mg / Nm ^3, dust 3g /
Waste gas from garbage incineration plants containing Nm ³ (16000 Nm ³ /
Time, 250 ° C.), an aqueous solution of the metal trapping agent shown in Table 4 was sprayed into the flue so that the metal trapping agent was supplied as a solid component at a rate of 300 mg / Nm ³ , and the waste gas was discharged. After reacting mercury with the metal collector, dust was collected with a bag filter. Table 4 shows the results of measuring the concentration of mercury remaining in the waste gas after passing through the bag filter. Further, using 50 g of dust collected by a bag filter, Examples 1 to 3 were used.
The concentration of the metal eluted in water was measured in the same manner as described above. Table 4 shows the results.

[0030]

[Table 4]

Examples 13 to 16, Comparative Example 5 32 mg / kg of lead, 7 mg / kg of mercury, 8 mg / k of zinc
g of wastewater containing 7 g of an aqueous solution (or dispersion) of the metal collecting agent shown in Table 5 in an amount of 7 mg per liter of the wastewater.
(In terms of solid content), the mixture was stirred at 20 ° C. for 20 minutes, and then allowed to stand. Then, generated flocs were separated and removed. Table 5 shows the results of measuring the residual metal concentration in the wastewater after removing the flocs.

[0032]

[Table 5]

Example 17, Comparative Example 6 Per 100 g of the dust used in Examples 1 to 3, different amounts of the metal collector shown in Table 6 were added (1 g in terms of solid matter, 2 g).
g, 3 g, 4 g, 5 g), and the amount of mercury eluted from the treated dust was measured in the same manner as in Examples 1 to 3 (provided that pH =
No. 6 only eluted into water), the relationship between the amount of metal scavenger added and the ability to immobilize mercury was examined. The results are shown in Table 6.

[0034]

[Table 6]

[0035]

As described above, the metal trapping agent of the present invention exhibits excellent trapping power for mercury and cadmium as well as the conventional dithiocarbamic acid type metal trapping agent, Therefore, according to the metal collecting agent of the present invention, wastewater containing lead and zinc, solid waste, and waste gas can be effectively treated. Further, since the metal trapping agent of the present invention has an excellent binding force to metals even under acidic conditions, solid waste treated with the metal trapping agent of the present invention was exposed to acid rain and the like. Even in such a case, there is no fear that the metal is eluted again from the solid waste.
Further, the metal-collecting agent of the present invention further reduces the concentration of residual metal in wastewater or waste gas and the concentration of metal eluted from solid waste compared to a dithiocarbamic acid-type metal-collecting agent obtained by an ordinary method. The waste can be reduced, and waste such as wastewater and solid waste can be more safely treated. Further, according to the method of the present invention, a metal collecting agent having the above-mentioned excellent metal collecting effect can be effectively obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B09C 1/08 B09B 3/00 304K B09B 3/00 304G C02F 1/62 ZAB 304J (72) Inventor Kazuo Hosoda 4-66, Horikiri, Katsushika-ku, Tokyo Miyoshi Oil & Fat Co., Ltd. (72) Inventor Masafumi Moriya 4-66-1, Horikiri, Katsushika-ku, Tokyo Miyoshi Oil & Fat Co., Ltd. F-term (reference) 4D002 AA29 AA31 AA40 AC04 AC10 BA03 BA14 CA01 DA61 EA05 HA01 4D004 AA28 AA36 AA37 AA41 AA43 AB03 AC07 CA34 CB21 CB42 CC06 4D038 AA08 AB63 AB69 AB73 AB74 BB18 4D059 BF20 DB08 DB21 4H006 AA01 AA03 AB99

Claims (2)

[Claims] 1. A compound formed by condensation of an amine having at least one primary amino group with an aldehyde.
The amino compound having no secondary amino group and having at least one secondary amino group has a metal-capturing functional group introduced by substituting with active hydrogen bonded to the nitrogen atom of the secondary amino group. A metal collector having at least one of an acid group and a salt of a dithioacid group. 2. An amino compound having at least one primary amino group and an aldehyde is polycondensed to obtain an amino compound having no primary amino group and having at least one secondary amino group. Then, the amino compound is reacted with carbon disulfide to form a dithioic acid group as a metal-trapping functional group bonded to the nitrogen atom of the secondary amino group of the amino compound.
A method for producing a metal collecting agent, comprising introducing at least one of salts of a dithioacid group.