JP2007146089A - Low-temperature storage stabilizing agent for heavy metal immobilization agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-temperature storage stabilizing agent effective for preventing the precipitation in low-temperature storage by adding the agent to an aqueous solution of potassium dithiocarbamate which is a conventional heavy metal immobilization agent used at a high concentration and having the problem of precipitation in low-temperature storage. <P>SOLUTION: The low-temperature storage stabilizing agent for a heavy metal immobilization agent (A) having a potassium dithiocarbamate group is composed of an oligomer (B) having potassium salt of one or more functional groups selected from a carboxy group, sulfo group, phosphoric acid group and phosphonic acid group and having a number-average molecular weight of 1,000-30,000. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a low-temperature storage stabilizer for heavy metal fixing 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 a drug added to immobilize heavy metals present in an aqueous solution or suspension of the solution to prevent elution of heavy metals, a high concentration dithiocarbamate (potassium salt, etc.) aqueous solution (for example, see Patent Document 1), etc. Heavy metal immobilizing agents are used.

JP-A-8-224560

  However, since heavy metal immobilizing agents such as dithiocarbamate (especially potassium salt) aqueous solution are used at high concentrations, storage stability at low temperatures is poor, and when used after low-temperature storage, it is treated by precipitation of dithiocarbamate components. There are problems such as clogging of equipment piping and chemical pumps.

  As a result of intensive studies to solve this problem, the present inventors have reached the present invention. That is, the present invention has a potassium base having one or more functional groups selected from the group consisting of a carboxyl group, a sulfo group, a phosphoric acid group and a phosphonic acid group, and has a number average molecular weight of 1,000 to 30. It is a low-temperature storage stabilizer for heavy metal fixing agent (A) having potassium dithiocarbamate consisting of 1,000 oligomers (B).

  The low-temperature storage stabilizer for heavy metal immobilizing agents of the present invention does not precipitate even at a low temperature even when (A) is a highly concentrated aqueous solution by adding to the heavy metal immobilizing agent (A) having potassium dithiocarbamate. It has an excellent effect of facilitating storage and storage at low temperatures.

The oligomer (B) in the present invention has a potassium base of one or more functional groups selected from the group consisting of a carboxyl group, a sulfo group, a phosphoric acid group and a phosphonic acid group, and has a number average molecular weight (hereinafter referred to as An oligomer having an abbreviation of Mn of 1,000 to 30,000 (preferably 2,000 to 20,000). Of the functional groups in the oligomer (B), a potassium base of a carboxyl group is preferable from the viewpoint of low-temperature storage stability.
If the Mn of (B) is less than 1,000, the effect of low-temperature storage stability is poor, and if it exceeds 30,000, the solubility in the aqueous solution of (A) becomes poor and the oligomer itself precipitates under low-temperature storage. Problems arise.
Here, the Mn is measured by a gel permeation (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 1ml / min
[4] Injection conditions: sample concentration 0.25%, injection volume 200 μl, column temperature 40 ° C.

  The oligomer (B) may be a potassium salt after polymerization of a vinyl monomer containing one or more functional groups selected from the group consisting of a carboxyl group, a sulfo group, a phosphoric acid group and a phosphonic acid group, You may superpose | polymerize, after making this vinyl monomer into potassium salt. From the viewpoint of production, a method of forming a potassium salt after polymerization is preferred.

  Carboxy group-containing vinyl monomers (including acid anhydrides) include aliphatic vinyl monomers [C3-18, such as (meth) acrylic acid, (anhydrous) maleic acid, monoalkyl maleate [alkyl group is carbon number (hereinafter C 1-8] ester, fumaric acid, monoalkyl fumarate (alkyl group is C1-8) ester, crotonic acid, itaconic acid, itaconic acid monoalkyl (alkyl group is C1-8) ester, itaconic acid glycol ( Glycol is C2-8) monoether, citraconic acid, citraconic acid monoalkyl (C1-8) ester], aromatic vinyl monomers [C7-15, such as cinnamic acid and vinylbenzoic acid], alicyclic vinyl monomers [C8- 15, eg vinylcyclohexane], and mixtures thereof;

  Examples of the sulfo group-containing vinyl monomer include C2-18, for example, 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) acryloyloxypropylsulfonic 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 mixtures thereof;

Examples of the phosphoric acid group-containing vinyl monomer include C5-18, such as hydroxyalkyl (meth) acrylate (C2-8 of alkyl group) phosphoric acid monoester [2-hydroxyethyl (meth) acryloyl phosphate and phenyl-2-acryloyloxy. Ethyl phosphate and the like] and mixtures thereof;
Examples of the phosphonic acid group-containing vinyl monomer include C5-18, for example, alkyl (meth) acrylate (C2-28 of an alkyl group) phosphonic acid [for example, 2-acryloyloxyethylphosphonic acid], and mixtures thereof.

  The monomer constituting (1) contains other monomers such as hydrophobic vinyl monomers [vinyl hydrocarbons, epoxy group-containing (meth) acrylates, halogen-containing monomers, hydroxyl group-containing monomers, etc.] and hydroxyl group-containing vinyl monomers as necessary. Can be made. Here, the hydrophobic monomer means one having a solubility in water at 20 ° C. (g / 100 g of water) of less than 1.

Vinyl hydrocarbons include C3-30, such as propylene, isobutylene, nonene, styrene and 1-methylstyrene.
Examples of the epoxy group-containing (meth) acrylate include C6 to 20, for example, glycidyl (meth) acrylate.
Halogen-containing monomers include C2-8, such as vinyl chloride.
Examples of hydroxyl group-containing vinyl monomers include C3-30, such as monofunctional monomers [hydroxystyrene, N-methylol (meth) acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol (Mn 200 to 20,000). Mono (meth) acrylate, (meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-buten-3-ol, 2-buten-1-ol], bifunctional monomer [2-butene-1,4- Diol, 2-hydroxyethylpropenyl ether, etc.], and trifunctional or higher monomers [sucrose allyl ether, etc.].

  The proportion of the hydrophobic vinyl monomer in the total monomers constituting (B) is preferably 40 mol% or less, more preferably 0 to 20 mol% from the viewpoint of the water solubility of (B); The proportion is preferably 40 mol% or less, more preferably 0 to 20 mol% from the viewpoint of the low temperature storage stability of (A).

  In the oligomer (B), one or any combination of monomers containing a potassium base of one or more functional groups selected from the group consisting of the carboxyl group, sulfo group, phosphoric acid group and phosphonic acid group, Or, if necessary, the above-mentioned other monomer may be included in the range in which (B) does not become water-insoluble (co) polymer (addition in the case of copolymer is random and / or block) Any), and mixtures thereof.

Examples of the polymerization method include a radical polymerization method in which various arbitrary radical initiators, chain transfer agents and the like are 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 other inorganic peroxides Products such as 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 more hydroxyl groups in the molecule [molecular weight of 32 or more and Mn of 50,000 or less, such as methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol (molecular weight of 100 And Mn 50,000 or less) and polyethylene polypropylene glycol (molecular weight 100 or more and Mn 50,000 or less)], compounds having one or more amino groups in the molecule [for example, ammonia and amines (C1-30, for example methyl Amine, dimethylamine, triethylamine and propanolamine)] and the following compounds (monovalent and polyvalent thiols) having one or more thiol groups in the molecule.

Monovalent thiols include aliphatic thiols [C1-20, such as methanethiol, ethanethiol, propanethiol, n-octanethiol, n-dodecanethiol, hexadecanethiol, n-octadecanethiol, 2-mercaptoethanol, mercaptoacetic acid, 3-mercaptopropionic acid, 1-thioglycerol, thioglycolic acid monoethanolamine), 1-thioglycerol, thioglycolic acid monoethanolamine, thiomaleic acid, cysteine and 2-mercaptoethylamine], alicyclic thiols (C5-20) , Eg cyclopentanethiol and cyclohexanethiol) and aromatic (aliphatic) thiols (C6-12, eg benzenethiol and benzyl mercaptan and thiosalicylic acid);
As the polyvalent thiol, dithiol [aliphatic (C2-40) dithiol (for example, ethanedithiol, diethylenedithiol, triethylenedithiol, propanedithiol, 1,3- and 1,4-butanedithiol, 1,6-hexanedithiol, Neopentanedithiol, etc.), alicyclic (C5-20) dithiols (eg cyclopentanedithiol and cyclohexanedithiol) and aromatic (C6-16) dithiols (eg benzenedithiol, biphenyldithiol)] and trithiols (C3-20, eg Thioglycerin).

In the present invention, as the dithiocarbamic acid component constituting the counter anion of the potassium ion of the heavy metal immobilizing agent (A) having a potassium dithiocarbamate base,
(1) C1-8 chain, branched or cyclic (cyclo) alkyldithiocarbamic acid,
(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 or cyclic (cyclo) alkylbisdithiocarbamic acid,
(4) C1-32 chain, branched or cyclic (cyclo) alkyltrisdithiocarbamic acid,
(5) C1-32 chain, branched or cyclic (cyclo) 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; measured by GPC method) 1,000 to 4,000 polyethyleneimine and carbon disulfide reaction product,
(10) A polycondensate polyamine (Mw 1,000 to 4,500) obtained by polycondensation of polyamine and epihalohydrin and a reaction product of carbon disulfide,
(11) A reaction product of polyvinylamine (Mw 1,000 to 100,000) and carbon disulfide, a mixture thereof, and the like.

  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) polyamines diamines (phenylenediamine, tolylenediamine, xylenediamine, diphenylmethanediamine and diaminophenyl ether), etc. (iv) C3-20 heterocyclic polyamines
Diamines (eg piperazine); and trivalent or higher polyamines (eg 1-aminoethylpiperazine and melamine)
Among these, from the viewpoint of heat stability of the formed dithiocarbamic acid potassium salt, preferred is the diamine in (i), more preferred is the diamine in (iv), and particularly preferred is piperazine.

 Of the heavy metal immobilizing agents (A), from the viewpoint of heavy metal scavenging ability, the potassium salts of (3) to (11) are preferred, piperazine mono- and potassium dithiocarbamate, and mixtures thereof are particularly preferred. Is a piperazine potassium bisdithiocarbamate and a mixture of piperazine mono- and potassium bis-dithiocarbamate (weight ratio of mono / bis is from the viewpoint of the generation of toxic gases such as carbon disulfide and hydrogen sulfide and the ability to capture heavy metals. Preferably 0.1 / 99.9 to 30/70, more preferably 1/99 to 15/85).

The low-temperature storage stabilizer of the present invention is used by blending with the heavy metal fixing agent (A). The blending ratio of the low temperature storage stabilizer and the heavy metal fixing agent (A) is preferably low temperature storage stable with respect to 100 parts by weight of the heavy metal fixing agent (A) from the viewpoint of low temperature storage stability and heavy metal fixing effect. The agent is 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight.
The storage temperature of the heavy metal fixing agent composition comprising the low temperature storage stabilizer and the heavy metal fixing agent (A) is usually -15 to 40 ° C., the precipitation suppression of (A) at low temperature, and the action of the heavy metal fixing agent and oligomer. From the viewpoint of the effect, it is preferably −10 ° C. to 30 ° C.

Examples of a method for producing a heavy metal fixing agent composition comprising the heavy metal fixing agent (A) and the oligomer (B) include the following methods.
[1] Add the aqueous solution (B) or (B) to the aqueous solution (A).
[2] Add the aqueous solution (A) or (A) to the aqueous solution (B).
[3] The mixture of (B) and (A) is dissolved in water.

The temperature conditions in [1] and [2] above are 0 to 90 ° C., and the stirring conditions are not particularly limited as long as they are uniformly mixed.
The aqueous solution pH of the heavy metal immobilizing agent composition is usually 12 or more. The lower limit is preferably 12.2, more preferably 12.5 from the viewpoint of the stability of the heavy metal immobilizing agent during storage, and the upper limit is preferably 14 from the same viewpoint. 0.0, more preferably 13.8. Here, the aqueous solution pH is a value measured with a pH meter (Model No. M-12, manufactured by Horiba, Ltd.) at 25 ° C. for the 30 wt% aqueous solution of (A), and the same applies hereinafter.

  (A) in 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, soil It is more effective in immobilizing heavy metals in aqueous solutions and suspensions such as solid powder such as sludge, slurries, industrial wastewater, smoke washing wastewater, leachate from landfills, etc., especially incineration (flying ash) It is extremely effective for fixing heavy metals inside.

  The amount of (A) used in 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) Based on their total weight, and in the case of liquid and slurry, the total weight of solid content, the same shall apply hereinafter)), from the viewpoint of the effect of immobilizing heavy metal, the preferred lower limit is 0.1%, more preferably as solid content The upper limit is preferably 0.2%, particularly preferably 0.3%, and the upper limit is preferably 30%, more preferably 20%, and particularly preferably 10% from the viewpoint of drug cost.

  When the heavy metal fixing agent composition in 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 (meth) acrylate copolymer, copolymer of acrylamide and dialkylaminoethyl (meth) acrylate quaternization product Etc.], quaternized products of dialkylaminoethyl methacrylate polymers, polyethyleneimine, natural products [guar gum, alginate, starch derivatives, chitosan, etc.] and the like.
The amount of the flocculant used is preferably 0.0001 to 3%, based on the weight of the heavy metal-containing material, usually 5% or less and from the viewpoint of exhibiting a sufficient aggregating effect.

Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.
Nonionic surfactants include, for example, alkylene oxide (hereinafter abbreviated as AO) [C2-4, such as ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), butylene oxide, and these. Combination of two or more types] addition type nonionic surfactant [AO added directly to higher alcohol (C8-18), higher fatty acid (C12-24) or higher alkylamine (C8-24) (molecular weight 158 or more and Mn 200,000 or less); polyalkylene glycol obtained by adding AO to glycol (molecular weight 150 or more and Mn 6,000 or less) and a higher fatty acid or the like; polyhydric alcohol (ethylene glycol, propylene glycol) , Glycerin, pentaerythritol, sorbitan, etc. A product obtained by reacting a higher fatty acid with a higher fatty acid) and an esterified product obtained by reacting a higher fatty acid (with a molecular weight of 250 or more and Mn 30,000 or less), or a product obtained by adding AO to a higher fatty acid amide (molecular weight). 200 or more and Mn 30,000 or less), polyvalent (divalent to octavalent or more) alcohol alkyl (C3-60 alkyl group) ether added with AO (molecular weight 120 or more and Mn 30,000 or less), etc. And a polyhydric alcohol (C3-60) type nonionic surfactant [polyhydric alcohol fatty acid (C3-60) ester, polyhydric alcohol alkyl (C3-60 of alkyl group) ether, fatty acid (C3 60) alkanolamides, etc.].

  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 [of C8-16 Carboxymethylated salts such as aliphatic alcohols and / or EO (1 to 10 mol) adducts thereof], sulfate esters [higher alcohol sulfate salts (sulfate esters of C8-18 fatty acid alcohols, etc.)], Higher alkyl ether sulfates [sulfate esters of C8-18 fatty acid alcohol EO (1-10 mol) adducts, etc.], sulfated oils (natural unsaturated oils or unsaturated waxes are sulfated as they are, Sulphated fatty acid ester (unsaturated fatty acid lower alcohol ester) ), Sulfated olefin (sulfurized olefin of C12-18, neutralized), sulfonate [alkylbenzene sulfonate, alkylnaphthalene sulfonate, sulfosuccinic acid 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; 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 poly Oxyethylenetrimethylammonium chloride; sapamine-type quaternary ammonium salts such as stearamide ethyl diethyl methyla Monium methosulphate], amine salt type [inorganic or organic acid salt of higher aliphatic amine (C12-60, such as laurylamine, stearylamine, cetylamine, hardened tallow amine, rosinamine); lower amine (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 amount of the surfactant used 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 fixing agent composition in the present invention to a heavy metal-containing material, it is usually added as a 20-70% by weight aqueous solution, or as an aqueous solution further diluted with water as necessary to prevent scattering of the heavy metal-containing material. Although a method is mentioned, a heavy metal fixing agent composition and water may be added separately, and when adding separately, which may be added first. Moreover, when the heavy metal-containing material is in the form of a slurry, only the heavy metal fixing agent composition 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 the examples, “part” means “part by weight”, “%” means “% by weight”, and “pH” of the aqueous solution represents the value measured by the above-mentioned method.
○ No crystal precipitation × Crystal precipitation

Production Example 1
(Production of aqueous solution of potassium piperazine bisdithiocarbamate)
474 parts of water and 129 parts of piperazine were charged and dissolved in a reaction vessel that can be cooled and stirred and purged with nitrogen, and then charged with 168 parts of potassium hydroxide and stirred at 200 rpm. After confirming that the solid in the reaction vessel became a slurry, 250 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, and then the unreacted carbon disulfide was removed to obtain a 47.2% aqueous solution of potassium piperazine bisdithiocarbamate (A1). The pH of the aqueous solution was 13.
Production Example 2
(Production of aqueous solution of potassium piperazine bisdithiocarbamate and potassium piperazine monodithiocarbamate)
In Production Example 1, except that 134 parts of piperazine, 171 parts of potassium hydroxide and 226 parts of carbon disulfide were used, the same procedure as in Production Example 1 was carried out, and a mixture of potassium piperazine monodithiocarbamate and potassium piperazine bisdithiocarbamate (A2) ( A 47.5% aqueous solution having a weight ratio of mono / bis was 6/94). The pH of the aqueous solution was 13.

Example 1
To 100 parts of the 47.2% aqueous solution of (A1), 1, 2, 6, 10 parts of 40% aqueous solution of potassium salt of acrylic acid polymer (Mn6,000) (B1) were added and mixed. 40 ml of each obtained aqueous solution was put into a hermetically sealed glass container having an inner diameter of 2.5 cm, a height of 11 cm, and a capacity of 50 ml, and left in an incubator adjusted to −10 ° C. for 1 week to test for crystal precipitation. The results are shown in Table 1.

Examples 2-4
In Example 1, instead of the 40% aqueous solution of (B1), a 40% aqueous solution of potassium salt (Mn3,000) (B2) of 2-acrylamido-2-methylpropanesulfonic acid polymer, 2-hydroxyethylacryloyl phosphate Except using 40% aqueous solution of polymer potassium salt (Mn3,000) (B3) or 40% aqueous solution of potassium salt of 2-acryloyloxyethylphosphonic acid polymer (Mn4,000) (B4). It carried out similarly to Example 1 and tested the presence or absence of crystal precipitation. The results are shown in Table 1.
Comparative Example 1
In Example 1, it carried out similarly to Example 1 except having used the 40% aqueous solution of the sodium salt (Mn6,000) (C1) of an acrylic acid polymer instead of (B1), and the presence or absence of crystal precipitation was tested. . The results are shown in Table 1.
Comparative Example 2
40 ml of a 47.2% aqueous solution of (A1) was placed in the same sealed glass container as in Example 1, and the presence or absence of crystal precipitation was tested in the same manner as in Example 1. The results are shown in Table 1.
Examples 5-8
In Examples 1 to 4, tests were conducted in the same manner as in Examples 1 to 4 except that a 47.5% aqueous solution of (A2) was used instead of the 47.2% aqueous solution of (A1), and the presence or absence of crystal precipitation was tested. did. The results are shown in Table 2.
Comparative Examples 3 and 4
In Comparative Examples 1 and 2, the same procedure as in Comparative Examples 1 and 2 was performed except that the 47.5% aqueous solution of (A2) was used instead of the 47.2% aqueous solution of (A1), and the presence or absence of crystal precipitation was tested. did. The results are shown in Table 2.

  From the results of Tables 1 and 2, the heavy metal fixing agent composition to which the low-temperature storage stabilizer of the present invention is added exhibits no crystal precipitation at -10 ° C for one week and is excellent in low-temperature storage stability. I understand.

  The low-temperature storage stabilizer of the present invention is added to a heavy metal fixing agent having potassium dithiocarbamate base, so that the fixing agent can be stored or stored at low temperature without precipitation at low temperature even in a high concentration aqueous solution. Is very useful as a low-temperature storage stabilizer for heavy metal fixing agents.

Claims (3)

Oligomer having a potassium base of one or more functional groups selected from the group consisting of a carboxyl group, a sulfo group, a phosphoric acid group and a phosphonic acid group and having a number average molecular weight of 1,000 to 30,000 (B A low-temperature storage stabilizer for heavy metal immobilizing agent (A) having a potassium base of dithiocarbamate, comprising: The stabilizer according to claim 1, wherein (B) is a polymer of a vinyl monomer having a potassium base of the functional group. The polymer comprises a potassium salt of one or more vinyl monomers selected from the group consisting of a carboxyl group-containing vinyl monomer, a sulfo group-containing vinyl monomer, a phosphate group-containing vinyl monomer, and a phosphonic acid group-containing vinyl monomer. The stabilizer according to claim 2, wherein the stabilizer is a homopolymer or a copolymer which may contain a vinyl hydrocarbon monomer as long as the copolymer does not become insoluble in water.