JP4801405B2 - Heavy metal fixing agent and method for improving stability of heavy metal fixing agent - Google Patents

Description

  The present invention relates to a heavy metal fixing agent. More particularly, the present invention relates to a heavy metal immobilizing agent that can immobilize heavy metals in a heavy metal-containing material to prevent elution of heavy metals, and a method for improving the stability of the heavy metal immobilizing agents.

Conventionally, incineration (flying ash) [meaning incineration ash or incineration fly ash; ], Solid powder such as slag, soil, sludge, or slurry or factory effluent, smoke washing effluent (drainage generated when washing soot attached to chimneys in garbage incinerators, etc.), leachate from landfill sites, etc. As an agent to be added to immobilize heavy metals present in an aqueous solution or suspension to prevent elution of heavy metals, dithiocarbamic acid (salt) aqueous solutions (for example, see Patent Documents 1 and 2) are known. Yes.
However, with conventional dithiocarbamic acid (salt) aqueous solutions, toxic gases such as hydrogen sulfide and carbon disulfide may be generated during storage, transportation, and use of the aqueous solution. A method of stabilizing the aqueous solution of the oxidizing agent by maintaining the pH at 13 or higher (for example, see Patent Document 3), or a method of adjusting the pH of the diluted solution when the heavy metal fixing agent is diluted with water to 12 or higher. (For example, see Patent Document 4).

JP-A-8-224560 Japanese Patent Laid-Open No. 11-16938 Japanese Patent Laid-Open No. 10-109081 Japanese Patent Laid-Open No. 10-118612

  However, it is still not enough to suppress the generation of harmful gases. An object of the present invention is to provide a heavy metal fixing agent and a method for improving the stability of the heavy metal fixing agent in which the generation of these toxic gases is suppressed without impairing the effect of fixing the heavy metal.

As a result of intensive studies to solve this problem, the present inventors have reached the present invention.
That is, the present invention is based on the group consisting of a phosphate (B), a carboxyl group, a sulfo group, a hydroxyl group, a phosphoric acid group, a phosphonic acid group, and an alkali metal base thereof in an aqueous solution of dithiocarbamic acid (salt) (A). A one-component heavy metal fixing agent containing an oligomer (C) having a number average molecular weight of 1,000 to 30,000 having one or more functional groups selected, and an aqueous solution of dithiocarbamic acid (salt) (A) Number average molecular weight of 1,000 to 30 having acid salt (B) and at least one functional group selected from the group consisting of carboxyl group, sulfo group, hydroxyl group, phosphoric acid group, phosphonic acid group and these alkali metal bases , 000 oligomer (C), and a method for improving the stability of a heavy metal fixing agent.

  The present invention provides a heavy metal immobilizing agent and a method for improving the stability of a heavy metal immobilizing agent, without impairing the immobilization effect of the heavy metal, and during storage, transportation and use of the heavy metal immobilizing agent. It is extremely useful because it has the effect of suppressing the generation of toxic gases such as.

Of the dithiocarbamic acid (salt) (A) in the present invention, as dithiocarbamic acid,
(1) Chain, branched and cyclic alkyldithiocarbamic acids having 1 to 8 carbon atoms (hereinafter abbreviated as C),
(2) phenyldithiocarbamic acid in which 1 to 5 hydrogen atoms may be substituted with a hydroxyl group or an alkyl ether group,
(3) C1-32 chain, branched and cyclic alkylbisdithiocarbamic acid,
(4) C1-32 chain, branched and cyclic alkyltrisdithiocarbamic acid,
(5) C1-32 chain, branched and cyclic alkyltetrakisdithiocarbamic acid,
(6) phenylbisdithiocarbamic acid in which 1 to 4 hydrogen atoms may be substituted with a hydroxyl group or an alkyl (C4-12) ether group,
(7) Phenyltrisdithiocarbamic acid in which 1 to 4 hydrogen atoms may be substituted with a hydroxyl group or an alkyl (C4-12) ether group,
(8) a reaction product of polyamine and carbon disulfide,
(9) Weight average molecular weight (hereinafter abbreviated as Mw) 4,000 or less reaction product of polyethyleneimine and carbon disulfide,
(10) A polycondensate having a Mw of 4,500 or less in which polyamine and epihalohydrin are polycondensed, and a reaction product of polyamine and carbon disulfide,
(11) A reaction product of polyvinylamine and carbon disulfide,
And a mixture thereof.
The reaction product of polyamine and carbon disulfide (8) and the reaction product of polyethyleneimine and carbon disulfide (9) can be obtained by the method described in JP-A-3-231922.

  Examples of the polyamine in the above (8) and (10) include the following compounds having two or more imino groups or amino groups in which one or two active hydrogen atoms are bonded to a nitrogen atom.

(I) C2-22 aliphatic polyamine diamines (eg, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine and N, N′-dimethylethylenediamine); triamines (eg, diethylenetriamine, dipropylenetriamine and dibutylenetriamine); and 4 Or higher polyamines (eg, triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine and pentaethylenehexamine)
(Ii) C4-22 alicyclic polyamine diamines [eg 1,4-cyclohexanediamine, 1,3-bis (aminomethyl) cyclohexane, bis (4-aminocyclohexyl) methane and bis (4-amino-3-methyl) Cyclohexyl) methane]
(Iii) C6-20 aromatic (aliphatic) polyamine diamines (eg phenylenediamine, tolylenediamine, xylenediamine, diphenylmethanediamine and diaminophenyl ether)
(Iv) C3-20 heterocyclic polyamine diamines (eg piperazine); and triamines (eg 1-aminoethylpiperazine and melamine)

  Among these, from the viewpoint of the heat stability of the dithiocarbamic acid (salt) to be formed, the diamine in (i) is more preferable, and the diamine in (iv), particularly piperazine, is more preferable.

  Examples of the salt of dithiocarbamic acid include (1) to (11) alkali metal (for example, lithium, sodium, and potassium) salts, ammonium salts, amines [for example, C1-8 monoalkylamine, C2-16 dialkyl (alkyl group C1-8) amine, and C3-24 trialkyl (C1-8 amine of alkyl group) salt, C4-20 quaternary ammonium salt, and mixtures thereof.

  Among the above (A), from the viewpoint of heat stability, (3) to (11), salts thereof and mixtures thereof are more preferable, and alkali metal salts of (3) to (11) are particularly preferable. Preferred is the potassium salt of (8), and most preferred is the potassium salt of piperazine.

Phosphate (B) includes alkali metal (for example, sodium and potassium) salts of phosphoric acid, such as trisodium phosphate and tripotassium phosphate, alkaline earth metal (for example calcium and magnesium) salts of phosphoric acid, such as calcium phosphate And magnesium phosphate. Of these, alkali metal salts of phosphoric acid are preferable from the viewpoint of solubility in water, and tripotassium phosphate is more preferable.
The alkali metal salt of phosphoric acid may contain dihydrogen phosphate or monohydrogen phosphate in which hydrogen atoms of phosphoric acid are partially unreacted, and the content of these partially unreacted salts is Based on the total weight of the alkali metal salt, it is usually 10% or less, preferably 0 to 5%.
(B) is usually used as a powder or an aqueous solution. In the case of an aqueous solution, the concentration is usually 1 to 70% by weight, and preferably 10 to 60% by weight from the viewpoint of industrial ease of handling.

(C) in the present invention is a number average molecular weight [hereinafter referred to as Mn] having at least one functional group selected from the group consisting of a carboxyl group, a sulfo group, a hydroxyl group, a phosphoric acid group, a phosphonic acid group and these alkali metal bases. Abbreviated. The measurement is based on a gel permeation chromatography (GPC) method. same as below. ] 1,000 to 30,000 oligomers.
Of the functional groups in (C), an alkali metal (sodium, potassium, etc.) base is preferred from the viewpoint of storage stability, and a potassium base is more preferred. Of the carboxyl group, sulfo group, hydroxyl group, phosphoric acid group, phosphonic acid group, and alkali metal bases thereof, the carboxyl group, sulfo group, hydroxyl group, and alkali metal bases thereof are more preferable from the viewpoint of storage stability. Is a carboxyl group and / or its alkali metal base.
Here, the Mn is measured by the GPC method under the following conditions.
(1) Apparatus: HLC-8120GPC [manufactured by Tosoh Corporation]
(2) Column: Guardcolumn α, TSKgel α-3000,
TSKgel α-6000
(3) Eluent: methanol / water (30/70% v / v) sodium acetate 0.5% w / v, flow rate 1 ml / min
(4) Injection conditions: sample concentration 0.25%, injection volume 200 μl, column temperature 40 ° C.

Examples of the monomer constituting (C) include a carboxyl group, a sulfo group, a hydroxyl group, a phosphoric acid group and / or a phosphonic acid group-containing vinyl monomer.
Carboxyl group-containing vinyl monomers (including acid anhydrides) include aliphatic vinyl monomers [C3-30, such as (meth) acrylic acid, (anhydrous) maleic acid, monoalkyl maleates (C1-28 alkyl groups) esters. , Fumaric acid, monoalkyl fumarate (C1-28 of alkyl group) ester, crotonic acid, itaconic acid, monoalkyl itaconic acid (C1-25 of alkyl group) ester, glycol itaconic acid (C1-25 of glycol) monoether Citraconic acid, monoalkyl citraconic acid (C1-25 alkyl ester)], aromatic vinyl monomers [C7-30, eg cinnamic acid and vinylbenzoic acid], alicyclic vinyl monomers [C8-30, eg vinylcyclohexane And alkali metal salts thereof;

  Examples of the sulfo group-containing vinyl monomer include C2-30, such as vinyl sulfonic acid, (meth) allyl sulfonic acid, methyl vinyl sulfonate, styrene sulfonic acid, α-methyl styrene sulfonic acid, sulfopropyl (meth) acrylate, 2-hydroxy- 3- (meth) acryloxypropylsulfonic acid, 2- (meth) acryloylamino-2,2-dimethylethanesulfonic acid, 2- (meth) acryloyloxyethanesulfonic acid, 3- (meth) acryloyloxy-2-hydroxy Propanesulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 3- (meth) acrylamide-2-hydroxypropanesulfonic acid, alkyl (C3-18) allylsulfosuccinic acid and alkali metal salts thereof;

  Examples of the hydroxyl group-containing vinyl monomer include C4-30, such as monofunctional [for example, hydroxystyrene, N-methylol (meth) acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, (Meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-buten-3-ol, 2-buten-1-ol], bifunctional [eg 2-butene-1,4-diol and 2-hydroxy Ethyl propenyl ether], and trifunctional or higher [eg sucrose allyl ether];

Examples of the phosphoric acid group-containing vinyl monomer include C3-30, for example, hydroxyalkyl (meth) acrylate (C1-28 of alkyl group) phosphoric acid monoester [for example, 2-hydroxyethyl (meth) acryloyl phosphate and phenyl-2-acryloyl Oxyethyl phosphate] and alkali metal salts thereof;
Examples of the phosphonic acid group-containing vinyl monomer include C3-30, such as alkyl (meth) acrylate (C1-28 of an alkyl group) phosphonic acid [for example, 2-acryloyloxyethylphosphonic acid] and alkali metal salts thereof.

The monomer constituting (C) also includes a hydrophobic monomer (for example, vinyl hydrocarbon, epoxy group-containing (meth) acrylate, and halogen-containing monomer) as necessary.
Vinyl hydrocarbons include C3-30, such as propylene, isobutylene, nonene, styrene and 1-methylstyrene.
Examples of the epoxy group-containing (meth) acrylate include C4 to 20, for example, glycidyl (meth) acrylate.
Halogen-containing monomers include C2-8, such as vinyl chloride.
The proportion of the hydrophobic monomer in the total monomers constituting (C) is preferably 40 mol% or less, more preferably 0 to 20 mol%, from the viewpoint of the water solubility of (C).

The oligomer (C) includes a homopolymer of the above monomers or a copolymer obtained by any combination (addition form may be random and / or block), and a mixture thereof.
Examples of the polymerization method include a radical polymerization method in which an ordinary arbitrary radical initiator, chain transfer agent, or the like is added to an aqueous monomer solution for polymerization.
Examples of the radical initiator include water-soluble azo initiators [for example, azobisamidinopropane (salt) [for example, 2,2′-azobis (2-methylpropionamidine) dihydrochloride], azobiscyanovaleric acid (salt) And 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] (salt)], oil-soluble azo initiators (eg azobiscyanovaleronitrile, azobisisobutyronitrile and Azobiscyclohexanecarbonitrile), water-soluble peroxides (eg hydrogen peroxide, peracetic acid and t-butyl peroxide), oil-soluble peroxides (eg benzoyl peroxide and cumene hydroxy peroxide) and inorganic peroxides ( For example, ammonium persulfate and sodium persulfate).
The above peroxides may be used as a redox initiator in combination with a reducing agent, such as bisulfite (eg, sodium bisulfite, potassium bisulfite and ammonium bisulfite), reducing metal salts [eg, iron sulfate] (II)], tertiary amines [eg dimethylaminobenzoic acid (salt) and dimethylaminoethanol], amine complexes of transition metal salts [eg pentamethylenehexamine complex of cobalt (III) chloride and diethylenetriamine complex of copper (II) chloride And an organic reducing agent (for example, ascorbic acid). Further, the azo initiator, peroxide initiator, and redox initiator may be used alone or in combination of two or more initiators.
Examples of the chain transfer agent include compounds having one or two or more hydroxyl groups in the molecule [molecular weight 32 to Mn 50,000, such as methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol (molecular weight 100 to Mn 50 , 000) and polyethylene polypropylene glycol (molecular weight 100-Mn 50,000)], compounds having one or more amino groups in the molecule [eg ammonia and amines (C1-30, eg methylamine, dimethylamine, triethylamine) And propanolamine)] and compounds having one or more thiol groups in the molecule [for example, aliphatic mercaptans (C1-20, such as methyl mercaptan, ethyl mercaptan, propyl mecaptan, Captan, n-octyl mercaptan, n-dodecyl mercaptan, hexadecyl mercaptan, n-octadecyl mercaptan, 2-mercaptoethanol, mercaptoacetic acid, 3-mercaptopropionic acid, thioacetic acid, 1-thioglycerol, monoethanolamine thioglycolate, Thiomaleic acid, cysteine and 2-mercaptoethylamine), aliphatic dithiols (C2-40, eg ethylenedithiol, diethylenedithiol, triethylenedithiol, propylenedithiol, 1,3- and 1,4-butanedithiol, 1,6-hexane Dithiols and neopentyldithiols), alicyclic dithiols (C5-20, such as cyclopentanedithiols and cyclohexanedithiols) and aromatic dithiols (C6- 6, for example, benzene dithiol and biphenyl dithiol), trithiol (C3-20, e.g. include thioglycerol)].

  Mn of (C) is 1,000 to 30,000, preferably 2,000 to 20,000. If the Mn is less than 1,000, the harmful gas suppression effect of the heavy metal fixing agent and the low temperature storage stability of the heavy metal fixing agent are poor, and if the Mn exceeds 30,000, the solubility in the heavy metal fixing agent is poor. Or there exists a problem that an oligomer (or polymer) precipitates under low temperature storage.

In the present invention, the weight ratio (A) / (B) / (C) of (A), (B) and (C) is preferably from the viewpoint of heavy metal immobilization effect, harmful gas suppression and low-temperature storage stability. 10-99.5 / 0.5-90 / 0.01-10, more preferably 15-99 / 1-85 / 0.02-8, particularly preferably 20-98 / 2-80 / 0.03- 6.
When (A) / (B) / (C) is in the above range, the effect of suppressing the generation of toxic gas is extremely good.

The following method is mentioned as a method of containing (B) and (C) in the aqueous solution of (A).
[1] Add (B) and (C) to the aqueous solution of (A).
[2] Add (B) to the aqueous solution of (A) and (C).
[3] Add (A) and (B) to the aqueous solution of (C).
[4] A mixture of (A), (B) and (C) is dissolved in water.
[5] (C) and phosphoric acid are added to the aqueous solution of (A) to form (B).
[6] (A) and phosphoric acid are added to the aqueous solution of (C) to form (B).
[7] (A) is formed in the presence of (B) and / or (C). Water may be added later in water. Thereafter, (B) or (C) is added as necessary.
[8] (B) and (C) are added to dithiocarbamic acid, and then a salt is formed.
[9] (A) and (B) are added to the unneutralized product of (C), and then a salt is formed.
[10] (B) is added to an unneutralized product of dithiocarbamic acid and (C) to form a salt.

The temperature condition for containing (B) and (C) in the aqueous solution (A) is 0 to 90 ° C., and the stirring condition is not particularly limited as long as the mixture is uniformly mixed.
The aqueous solution pH of the heavy metal immobilizing agent of the present invention is usually 12 or more, the lower limit is preferably 12.2 from the viewpoint of stability during storage, more preferably 12.5, and the upper limit is preferably 14.0 from the same viewpoint. Preferably it is 13.8. Here, the pH of the aqueous solution is a value measured with a pH meter at 25 ° C. of a 30% by weight aqueous solution of the heavy metal immobilizing agent of the present invention, and so on.

  The heavy metal immobilizing agent of the present invention is effective for immobilizing heavy metals in heavy metal-containing materials of various properties such as block solids, powders, liquids, slurries, pastes, etc., but incineration (flying ash), ore, It is more effective in immobilizing heavy metals in aqueous solutions and suspensions such as solid powders and slurries such as soil and sludge, or industrial wastewater, smoke washing wastewater, leachate from waste landfills, especially incineration (flying) It is particularly effective for immobilizing heavy metals in ash.

  The amount of the heavy metal immobilizing agent of the present invention can be arbitrarily adjusted according to the heavy metal content contained in the heavy metal-containing material and is not particularly limited, but the weight of the heavy metal-containing material (in the case of solid, powder, paste) From the viewpoint of the effect of immobilizing heavy metals, the lower limit of the solid content is preferably 0.1%, more preferably 0.2%, based on the total weight of them and the total weight of solids in the case of liquids and slurries). %, Particularly preferably 0.3%, and from the viewpoint of drug cost, the upper limit is preferably 30%, more preferably 20%, and particularly preferably 10%.

When the heavy metal fixing agent of the present invention is added to a heavy metal-containing material, other additives may be used in combination.
Examples of other additives include a flocculant and a surfactant.

Examples of the flocculant include inorganic (aluminum sulfate, polyaluminum chloride, sodium aluminate, ferrous sulfate, ferric sulfate, ferric chloride, etc.), organic (polyacrylic acid (salt), acrylamide polymer [ Polyacrylamide, polyacrylamide partial hydrolyzate, polyacrylamide methylolation cationization product, quaternization product of acrylamide and dialkylaminoethyl methacrylate copolymer, copolymer of acrylamide and dialkylaminoethyl methacrylate quaternization product, etc.], dialkylaminoethyl Examples thereof include quaternized products of methacrylate polymers, polyethyleneimine, and natural product systems such as guar gum, alginates, starch derivatives, chitosan, and the like.
The addition amount of the flocculant is preferably 5% or less based on the weight of the heavy metal-containing material, and preferably 0.0001 to 3% from the viewpoint of exhibiting a sufficient aggregation effect.

Surfactants include nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants.
Examples of the nonionic surfactant include alkylene oxide (hereinafter abbreviated as AO) (C2-4) addition type nonionic surfactant [higher alcohol (C8-18), higher fatty acid (C12-24) or higher alkyl. AO [C2-4, for example, ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), butylene oxide, and a combination of two or more thereof] was directly added to the amine (C8-24) or the like. (Molecular weight: 158 to Mn 200,000); Polyalkylene glycol obtained by adding AO to glycol (Molecular weight: 150 to Mn 6,000) and higher fatty acid, etc .; Polyhydric alcohol (ethylene glycol, propylene glycol, Divalent to octavalent such as glycerin, pentaerythritol, sorbitan or so A product obtained by reacting a higher fatty acid with the above polyhydric alcohol) and an esterified product obtained by adding AO (molecular weight: 250 to Mn 30,000); a product obtained by adding AO to a higher fatty acid amide (molecular weight: 200 to Mn 30, 000), polyvalent (divalent to octavalent or higher) alcohol alkyl (C3-60) ether added with AO (molecular weight 120 to Mn30,000), and the like, and polyhydric alcohol (C3 60) type nonionic surfactants [polyhydric alcohol fatty acid (C3-60) ester, polyhydric alcohol alkyl (C3-60) ether, fatty acid (C3-60) alkanolamide, etc.] and the like.

  Examples of the anionic surfactant include carboxylic acid (saturated or unsaturated fatty acid of C8-22) or a salt thereof (a salt of sodium, potassium, ammonium, alkanolamine, etc.), a salt of carboxymethylated product [a fatty acid of C8-16]. Carboxymethylated salts such as aromatic alcohols and / or EO (1-10 mol) adducts thereof], sulfate esters [higher alcohol sulfate esters (sulfate esters of fatty acid alcohols of C8-18)], higher Alkyl ether sulfate salt [sulfate ester salt of EO (1-10 mol) adduct of C8-18 fatty acid alcohol, etc.], sulfated oil (natural unsaturated oil or unsaturated wax is neutralized by sulfation as it is ), Sulfated fatty acid esters (lower alcohol esters of unsaturated fatty acids were neutralized by sulfation) ), Sulfated olefin (sulfurized and neutralized olefin of C12-18), sulfonate [alkylbenzenesulfonate, alkylnaphthalenesulfonate, sulfosuccinate diester type, α-olefin (C12-18) Sulfonates, Igepon T-type, etc.] and phosphate esters [higher alcohol (C8-60) phosphate ester salts, higher alcohol (C8-60) EO adduct phosphate ester salts, alkyl (C4-60) phenol EO Adduct phosphoric acid ester salts, etc.].

  Cationic surfactants include quaternary ammonium salt types [tetraalkyl (C4-100) ammonium salts such as lauryltrimethylammonium chloride, didecyldimethylammonium chloride, dioctyldimethylammonium bromide, stearyltrimethylammonium bromide; trialkyl (C3 -80) benzylammonium salts such as lauryldimethylbenzylammonium chloride (benzalkonium chloride); alkyl (C2-60) pyridinium salts such as cetylpyridinium chloride; polyoxyalkylene (C2-4) trialkylammonium salts such as polyoxy Ethylenetrimethylammonium chloride; sapamine-type quaternary ammonium salts such as stearamide ethyl diethyl methylan Nium methosulphate], amine salt type [inorganic or organic acid salts of higher aliphatic amines (C12-60, such as laurylamine, stearylamine, cetylamine, hardened tallow amine, rosinamine); lower amines (C1-11) Higher fatty acid (stearic acid, oleic acid, etc.) salt; inorganic acid salt or organic acid salt such as EO adduct of aliphatic amine (C1-30); tertiary amine (C1-30, for example, triethanolamine monostearate, Inorganic acid salt or organic acid salt of stearamide ethyl diethyl methyl ethanolamine) and the like.

  Examples of amphoteric surfactants include amino acid type amphoteric surfactants such as sodium propionate of higher alkylamine (C12-18), betaine type amphoteric surfactant alkyl (C12-18) dimethylbetaine, sulfate ester type amphoteric interface. Activator [higher alkyl (C8-18) amine sulfate sodium salt, hydroxyethyl imidazoline sulfate sodium salt, etc.], sulfonate amphoteric surfactant (pentadecyl sulfotaurine, imidazoline sulfonic acid, etc.), phosphate ester And salt type amphoteric surfactants [phosphate ester amine salts of glycerin higher fatty acid (C8-22) esterified products, etc.].

  The addition amount of the surfactant is usually 5% or less, preferably 0.01 to 3%, based on the weight of the heavy metal-containing material.

  As a method for adding the heavy metal immobilizing agent of the present invention to a heavy metal-containing material, there is usually a method of adding as an aqueous solution of 20 to 70% by weight, further diluting with water as necessary to prevent scattering of the heavy metal-containing material. Although a heavy metal fixing agent and water may be added separately, when adding separately, which may be added first. Moreover, when the heavy metal-containing material is in a slurry state, only the heavy metal fixing agent may be added directly to the slurry.

The kneading apparatus for adding to and kneading the solid powder or slurry is not particularly limited, and examples thereof include ordinary ones such as a kneader and a Hobart mixer.
Moreover, there is no limitation in particular as a stirring apparatus at the time of adding and stirring to the said waste_water | drain, All the stirring apparatuses will be mentioned if stirring is possible.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this. In addition, the part in an Example is a weight part,% is weight%, pH of aqueous solution is a pH meter [model number M-12 made by Horiba, Ltd.] at 25 degreeC of heavy metal fixing agent 30 weight% aqueous solution. To express.

Synthesis Example 1 Synthesis of aqueous solution of potassium piperazine bisdithiocarbamate In a reaction vessel that can be cooled and stirred and purged with nitrogen, 600 parts of water and 100 parts of piperazine were charged and dissolved, and then 130 parts of potassium hydroxide was charged at 200 rpm. Stir. After confirming that the solid in the reaction vessel became a slurry, 177 parts of carbon disulfide was added dropwise at 35 ° C. in a nitrogen atmosphere. After completion of the dropwise addition, the mixture was aged at the same temperature for 3 hours to obtain a 36.3% aqueous solution (A1) of potassium piperazine bisdithiocarbamate. The pH of the aqueous solution was 13.

Example 1
15 parts of a 44% aqueous solution of tripotassium phosphate (B1), 85 parts of (A1) and 0.5 part of sodium acrylate polymer (Mn10,000) (C1) were mixed and stirred. A 37.3% aqueous solution (X1) was obtained. The pH of the aqueous solution was 13.

Example 2
5 parts of (B1), 95 parts of (A1) and 1 part of (C1) were mixed and stirred to obtain a 36.7% aqueous solution (X2) of the heavy metal fixing agent of the present invention. The pH of the aqueous solution was 13.

Example 3
In Example 2, it replaced with 1 part of (C1), it carried out similarly to Example 2 except having used 1 part of potassium acrylate polymer (Mn10,000) (C2), and the heavy metal fixing agent of this invention was used. A 36.7% aqueous solution (X3) was obtained. The pH of the aqueous solution was 13.

Example 4
In Example 2, it replaced with 1 part of (C1), it carried out similarly to Example 2 except having used 1 part of acrylic acid polymer (Mn10,000) (C3), and 36 of the heavy metal fixing agent of this invention. A 7% aqueous solution (X4) was obtained. The pH of the aqueous solution was 12.5.

Example 5
Example 2 was carried out in the same manner as in Example 2 except that 1 part of 2-acrylamido-2-methylpropanesulfonic acid potassium salt polymer (Mn10,000) (C4) was used instead of 1 part of (C1). As a result, a 36.7% aqueous solution (X5) of the heavy metal fixing agent of the present invention was obtained. The pH of the aqueous solution was 13.

Example 6
The heavy metal fixing agent of the present invention was carried out in the same manner as in Example 2, except that 1 part of N-methylolacrylamide polymer (Mn5,000) (C5) was used instead of 1 part of (C1) in Example 2. Of 36.7% aqueous solution (X6) was obtained. The pH of the aqueous solution was 13.

Example 7
Example 2 was carried out in the same manner as in Example 2 except that 1 part of 2-hydroxyethylacryloyl phosphate potassium salt polymer (Mn3,000) (C6) was used instead of 1 part of (C1). A 36.7% aqueous solution (X7) of a heavy metal fixing agent was obtained. The pH of the aqueous solution was 13.

Example 8
Example 2 was carried out in the same manner as in Example 2 except that 1 part of 2-acryloyloxyethylphosphonic acid potassium salt polymer (Mn3,000) (C7) was used instead of 1 part of (C1) in the present invention. A 36.7% aqueous solution (X8) of a heavy metal immobilizing agent was obtained. The pH of the aqueous solution was 13.

<Toxic gas test>
Examples 1-8, Comparative Example 1
50 g of each of (X1) to (X8) and (A1) is weighed into a glass container with a sealed lid having a capacity of 200 ml (cylindrical shape having an inner diameter of 5 cm and a height of 10.2 cm), and the inside of the container is purged with nitrogen and sealed. After standing at 30 ° C. for 7 days, the concentration of carbon disulfide and hydrogen sulfide in the vessel was measured using a detector tube [carbon disulfide is NO. 13 Detector tube, hydrogen sulfide is NO. 4LL detector tube]. The results are shown in Table 1.
From Table 1, it can be seen that in Examples 1 to 8, generation of carbon disulfide and hydrogen sulfide is suppressed as compared with Comparative Example 1.

<Dissolution test>
Examples 1-8, Comparative Example 1
To 50 parts of fly ash generated by refuse incineration, 0.17 parts and 10 parts of water are added as solid metal fixing agent solid content of each of the above heavy metal fixing agents (X1) to (X8) and (A1), and 80 ° C. And kneading for 10 minutes using a spatula. The treated ash and untreated ash after kneading were subjected to an elution test (Environment Agency official announcement No. 13) to measure the concentration of the eluted lead ions. The results are shown in Table 2.
From Table 2, it can be seen that Examples 1-8 show the same heavy metal fixing effect as Comparative Example 1.

The heavy metal immobilizing agent of the present invention is one that suppresses the generation of toxic gases such as hydrogen sulfide and carbon disulfide during the storage, transportation and use of the heavy metal immobilizing agent without impairing the immobilization effect of the heavy metal. Because of this, solid metals or slurries such as incineration (flying) ash, mines, soil, sludge, or heavy metals present in aqueous solutions or suspensions such as industrial wastewater, smoke washing wastewater, leachate from waste landfills, etc. Widely used as a drug added to immobilize and prevent elution of heavy metals.

Claims (6)

An aqueous solution of dithiocarbamic acid (salt) (A) containing at least one selected from the group consisting of phosphate (B), carboxyl group, sulfo group, hydroxyl group, phosphoric acid group, phosphonic acid group and these alkali metal bases A one-component heavy metal immobilizing agent comprising an oligomer (C) having a functional group and a number average molecular weight of 1,000 to 30,000. The heavy metal fixing agent according to claim 1, wherein (B) is an alkali metal salt of phosphoric acid. The heavy metal fixing agent according to claim 1 or 2, wherein (C) is a potassium salt. The heavy metal immobilizing agent according to any one of claims 1 to 3, wherein the weight ratio of (A), (B) and (C) is from 10 to 99.5 / 0.5 to 90 / 0.01 to 10. The heavy metal immobilizing agent according to any one of claims 1 to 4, which is for incineration (flying) ash treatment containing a heavy metal. An aqueous solution of dithiocarbamic acid (salt) (A) containing at least one selected from the group consisting of phosphate (B), carboxyl group, sulfo group, hydroxyl group, phosphoric acid group, phosphonic acid group and these alkali metal bases A method for improving the stability of a heavy metal immobilizing agent, comprising adding an oligomer (C) having a functional group-containing number average molecular weight of 1,000 to 30,000.