JP2019076840A - Purification agent for heavy metal-containing aqueous solution, and method for purifying heavy metal-containing aqueous solution - Google Patents

Abstract

To provide a purification agent for aqueous solution containing heavy metals such as zinc and cadmium, and a method for purifying a heavy metal-containing aqueous solution using the purification agent, and a purification agent that suppresses clogging of pipes, strainers, etc., by suppressing a precipitation of poorly soluble salts at the time of mixing the purification agent with dilution water.SOLUTION: Heavy metals are removed from an aqueous solution containing heavy metals such as zinc and cadmium, by mixing: a purification agent for a heavy metal-containing aqueous solution containing 2 to 50 parts by weight of polyamine having a weight average molecular weight of 300 or more relative to 100 parts by weight of a salt of dithiocarbamic acid, and hydroxyaminocarboxylic acid having three or more carboxyl groups and/or a salt thereof; with dilution water such as drinking water, groundwater, industrial water and the like.SELECTED DRAWING: None

Description

  The present invention relates to a purifying agent capable of removing heavy metals from an aqueous solution containing heavy metals such as zinc and cadmium, and a method for purifying a heavy metal-containing aqueous solution using the same. A heavy metal treating agent and a heavy metal-containing aqueous solution purification method capable of suppressing clogging of pipes, strainers and the like even when used in combination with dilution water such as industrial water.

  The aqueous solution containing heavy metals such as zinc and cadmium is sent to waste water treatment equipment, for example, it is made alkaline by adding iron ions, and zinc ions, cadmium ions etc. are precipitated as hydroxides with iron ions and other contained ions. And the like, and separated from the aqueous solution and then discharged.

  The drainage standard for zinc content was previously set at 5 mg / L, but the drainage standard was strengthened from the viewpoint of aquatic organism conservation, and changed to 2 mg / L in 2006. However, 5 mg / L has been applied as an interim drainage standard to specified business sites belonging to 10 industries where it is extremely difficult to meet uniform drainage standards. In recent years, 2 mg / L, which is the zinc drainage standard, has been required.

  In addition, since cadmium is a very harmful heavy metal, in recent years, 0.03 mg / L or less has been required as a drainage standard, and the importance of wastewater treatment is increasing.

  By the way, for drainage from plating plant, electronic parts / machine parts manufacturing plant, automobile plant, thermal power plant, waste incineration plant etc, organic acids such as citric acid and gluconic acid, ethylenediaminetetraacetic acid (hereinafter abbreviated as EDTA) And compounds such as cyanide, amine, ammonia, sulfuric acid, polyphosphoric acid and the like, which have a complexing ability with heavy metals such as zinc and cadmium, and there are many cases where the above-mentioned hydroxide method can not be purified.

  On the other hand, after chemically treating a compound having a complexing ability with heavy metals such as zinc and cadmium, a method is known in which these heavy metals are insolubilized. However, for example, even if chemical treatments such as chlorine based chemical methods, electrolytic oxidation methods, hydrogen peroxide-ferrous salt methods, ozone oxidation methods and wet oxidation methods are used, oxidation reactions due to coexisting heavy metal elements It is a situation where sufficient purification treatment can not be performed due to problems such as inhibition and scale formation.

  As a technique for removing various heavy metal elements contained in waste water, for example, flocculation separation removal method by addition of inorganic coagulant or organic coagulant, removal method by electrolysis, adsorption by activated carbon, inorganic adsorbent or organic polymer material Removal methods, drying to evaporate the waste water by heating, reverse osmosis using a membrane, electrodialysis or ultrafiltration, etc. have been proposed.

Even when the above-described methods are used, there are many problems as described below, and there is a need to improve each method. For example,
(1) Agglomeration separation removal method can not fully process heavy metals,
(2) In the adsorption removal method, even if heavy metals can be adsorbed, a large amount of solid components are generated after treatment,
(3) In reverse osmosis, electrodialysis or ultrafiltration, etc., it is difficult to remove when organic matter is contained in the waste water, and the treatment cost is high,
(4) The drying method by heating evaporation is complicated processing method and high processing cost,
Etc.

  On the other hand, as a technique for removing various heavy metal elements contained in waste water, methods using a salt of dithiocarbamic acid as a heavy metal treatment agent in waste water have been proposed (see, for example, Patent Documents 1 to 4). However, in the methods described in these patent documents, the purification treatment effect of the heavy metal from the heavy metal-containing wastewater containing the compound having the ability to form a complex with the heavy metal is not sufficient.

  In addition, a heavy metal treating agent containing a polyamine having three or more amino groups in the molecule and a carbodithioate salt of an amine has been proposed (see, for example, Patent Document 5). However, in the method disclosed in Patent Document 5, the purification treatment effect of heavy metals such as zinc and cadmium is insufficient.

  By the way, as a method of using a chelating agent such as a salt of dithiocarbamic acid, when the chelating agent is directly added to a heavy metal-containing wastewater containing a compound having the ability to form a complex with a heavy metal, diluted water such as fresh water, underground water, industrial water, etc. The agent is diluted and mixed to a predetermined concentration and then added to the heavy metal-containing waste water containing the heavy metal and the compound having a complexing ability. These dilution waters contain various inorganic substances such as magnesium, calcium, silicon, iron, etc. By mixing the dilution water and the chelating agent, the inorganic substances in the dilution water are precipitated as a sparingly soluble salt, and clogging of the piping and nozzles There was a problem that caused

  In order to solve this problem, a method has been proposed for suppressing occlusion by using a chelating agent containing a hydroxyaminocarboxylic acid and a dithiocarboxylate (see, for example, Patent Document 6).

  However, although the chelating agent containing hydroxyaminocarboxylic acids and dithiocarboxylic acid salts has a sufficient inhibitory effect on clogging of piping, strainers, etc., the heavy metals from the heavy metal-containing wastewater containing compounds having the ability to form a complex with heavy metals. The purification treatment effect was not enough.

JP, 2009-249399, A JP, 2011-074350, A JP, 2014-88477, A JP, 2002-177902, A JP 2008-273995 A Patent No. 6048071

  The present invention has been made in view of the above problems, and an object thereof is a heavy metal treating agent capable of suppressing clogging of piping, strainer and the like even when used in combination with dilution water and the like, and heavy metal using the same The present invention provides a method of purifying heavy metals from waste water containing heavy metals containing a compound having a complexing ability with

  As a result of intensive studies to solve the above problems, the present inventors have found the cleaning agent for a heavy metal-containing aqueous solution of the present invention and the method for purifying a heavy metal-containing aqueous solution using the same, and completed the present invention. It reached.

  That is, the present invention has the following gist.

  [1] For a heavy metal-containing aqueous solution containing 2 to 50 parts by weight of a polyamine having a weight average molecular weight of 300 or more, and 3 or more of carboxyl groups, with respect to 100 parts by weight of a salt of dithiocarbamic acid Purifier.

  [2] Reaction product of an amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group, a salt of dithiocarbamic acid, carbon disulfide, and an alkali metal hydroxide The heavy metal-containing aqueous solution purifying agent according to the above [1], which is characterized in that

  [3] Reaction product of an amine compound having two or more amino groups selected from the group consisting of a primary amino group and a secondary amino group with a dithiocarbamic acid salt, carbon disulfide, and an alkali metal hydroxide The heavy metal-containing aqueous solution purifying agent according to the above [1], which is characterized in that

  [4] The heavy metal-containing aqueous solution according to the above [1], wherein the salt of dithiocarbamic acid is a reaction product of piperazine or tetraethylenepentamine, carbon disulfide, and an alkali metal hydroxide. Purifier.

  [5] The cleaning agent for a heavy metal-containing aqueous solution according to any one of the above [1] to [4], wherein the polyamine having a weight average molecular weight of 300 or more is a polyethyleneimine having a weight average molecular weight of 300 or more.

  [6] The cleaning agent for a heavy metal-containing aqueous solution according to any one of the above [1] to [4], wherein the polyamine having a weight average molecular weight of 300 or more is a polyethyleneimine having a weight average molecular weight of 1,800 to 200,000. .

  [7] Purification for a heavy metal-containing aqueous solution according to any one of the above [1] to [6] in a heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper A method of purifying a heavy metal-containing aqueous solution, comprising the steps of: removing the solid produced after adding the agent.

  [8] Purification for a heavy metal-containing aqueous solution according to any one of the above [1] to [6] in a heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper A method for purifying a heavy metal-containing aqueous solution, which comprises removing the solid produced after adding an agent and dilution water.

  [9] The heavy metal-containing aqueous solution further comprises a compound having a complexing ability with at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead, and copper [7] or [7] The heavy metal containing aqueous solution purification method as described in 8].

  [10] A compound having the ability to form a complex with at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper has in its molecule a functional group selected from the group consisting of a carboxyl group and an amino group It is a compound which it has, The purification method of heavy metal containing aqueous solution as described in said [9] characterized by the above-mentioned.

  [11] The method for purifying a heavy metal-containing aqueous solution according to any one of the above [7] to [10], wherein an inorganic coagulant is added before removing a solid substance.

  [12] The method for purifying a heavy metal-containing aqueous solution according to any one of the above [7] to [10], wherein an inorganic coagulant and a polymer coagulant are added before removing a solid substance.

  [13] The method for purifying a heavy metal-containing aqueous solution according to the above [11] to [12], wherein the inorganic coagulant is selected from the group consisting of an iron compound and an aluminum compound.

  The purification agent for a heavy metal aqueous solution of the present invention has a zinc concentration of 2 mg / L, even for a zinc-containing aqueous solution (for example, a compound having a complexing ability with zinc and an aqueous solution containing zinc) in which zinc purification treatment is difficult. It can be reduced to the following.

  The purification agent for a heavy metal aqueous solution of the present invention has a cadmium concentration of 0.03 mg even in a cadmium-containing aqueous solution (for example, a compound having a complexing ability with cadmium and a cadmium-containing solution) in which the purification treatment of cadmium is difficult It can be reduced to less than / L.

  The purification agent for a heavy metal aqueous solution according to the present invention is an aqueous solution containing heavy metals such as nickel, mercury, lead, copper, palladium and the like in addition to zinc and cadmium (for example, desulfurization waste water from a coal-fired power plant etc.) The zinc concentration can be reduced to 2 mg / L or less, the cadmium concentration can be reduced to 0.03 mg / L or less, and the concentration of heavy metals such as nickel, mercury, lead, copper, palladium and the like can be significantly reduced.

  The cleaning agent for an aqueous solution of heavy metal of the present invention is economical because the addition amount of a drug including dithiocarbamate can be reduced by containing a predetermined amount of polyamine having a weight average molecular weight of 300 or more.

  The heavy metal treating agent of the present invention does not cause clogging of piping, strainers, etc. even when it is mixed with diluting water such as fresh water, ground water, industrial water etc., heavy metal containing aqueous solution which is difficult to purify heavy metals such as zinc and cadmium. It can be cleaned up.

  Hereinafter, the present invention will be described in detail.

  The heavy metal treating agent of the present invention comprises 2 to 50 parts by weight of a polyamine having a weight average molecular weight of 300 or more and 3 or more of carboxyl groups and / or a salt thereof with respect to 100 parts by weight of carbodithioate of amine. It is characterized by including.

  By using a heavy metal treating agent comprising a carbodithioate salt of an amine, 2 to 50 parts by weight of a polyamine having a weight average molecular weight of 300 or more, and a hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof Even when mixed with dilution water such as tap water, ground water, industrial water, etc., precipitation of magnesium ions in the dilution water as a sparingly soluble salt is suppressed, and clogging of pipes, strainers, etc. does not occur, and It can purify heavy metal-containing aqueous solutions that are difficult to purify and process heavy metals such as zinc and cadmium.

  The reason why the hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof is effective for preventing clogging of piping etc. in combination with a carbodithioate of an amine is not clear, but three or more carboxyl groups The hydroxyaminocarboxylic acid and / or the salt thereof which is possessed is more likely to form a water-soluble complex with magnesium, as compared with the conventional aminocarboxylic acid and hydroxyaminocarboxylic acid having two or less carboxyl groups and / or the salt thereof. Since the solubility of the water-soluble complex is high, it is considered that the precipitation of magnesium ions as a poorly soluble salt can be effectively suppressed even in the presence of an amine carbodithioate.

  A cleaning agent for a heavy metal-containing aqueous solution comprising a carbodithioate salt of an amine, 2 to 50 parts by weight of a polyamine having a weight average molecular weight of 300 or more, and a hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof Not only magnesium but also the conventional antiscaling agent aminocarboxylic acid exhibits the same effect on effective calcium.

  The salt of dithiocarbamic acid used in the cleaning agent for a heavy metal-containing aqueous solution of the present invention is not particularly limited as long as it is a compound having a dithiocarbamyl group in the molecule. For example, a compound obtained by reacting an amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group, carbon disulfide and an alkali metal hydroxide can be mentioned. An amine compound having two or more amino groups selected from the group consisting of a primary amino group and a secondary amino group, a compound obtained by reacting carbon disulfide and an alkali metal hydroxide is more preferable.

  Specific examples of the amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group include diethylamine, piperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine. And hepta ethylene octamine and the like.

  Among them, preferred are compounds obtained by reacting piperazine or tetraethylenepentamine, carbon disulfide and an alkali metal hydroxide in view of zinc and cadmium processing performance and stability as a compound. However, in the salt of dithiocarbamic acid of tetraethylene pentamine, tetraethylene pentamine which is a raw material is an analogue [refer to the following formulas (2) to (4) in addition to the linear body of the main component [see the following formula (1)]. Since only the composition containing [] is industrially manufactured, the salt of dithiocarbamic acid obtained also becomes a composition, and there is a drawback that the quality control becomes complicated. On the other hand, salts of dithiocarbamic acid of piperazine do not have such disadvantages and are particularly preferred.

  As the alkali metal hydroxide, sodium hydroxide and potassium hydroxide are particularly preferable in terms of easy availability.

  Examples of polyamines having a weight-average molecular weight of 300 or more include polyethyleneimines having a weight-average molecular weight of 300 or more and polyetheramines having a weight-average molecular weight of 300 or more (polypropylene glycol, polyethylene glycol, etc. compounds having terminal hydroxyl groups converted to primary amino groups) Etc.). Among these, polyethyleneimines having a weight average molecular weight of 300 or more are preferable in view of the processing performance of heavy metals such as zinc and cadmium.

  The weight average molecular weight of the polyamine is preferably at least 1,800 from the viewpoint of improving the processing ability of zinc and cadmium. By setting the weight average molecular weight to 1800 or more, the amount of drug used including dithiocarbamate may be able to be reduced. Among these, polyethyleneimines having a weight average molecular weight of 1,800 or more are more preferable in terms of the treatment performance of heavy metals such as zinc and cadmium.

  The addition amount of the polyamine having a weight average molecular weight of 300 or more is 2 to 50 parts by weight, preferably 8 to 25 parts by weight with respect to 100 parts by weight of the dithiocarbamic acid salt. By adding 2 parts by weight or more, a sufficient zinc processing capacity can be obtained, but when it is added in excess of 50 parts by weight, the processing effect of zinc and cadmium is reduced.

  The hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof to be used in the cleaning agent for heavy metal-containing aqueous solution of the present invention is not particularly limited, and hydroxyethylethylenediaminetriacetic acid (HEDTA), diamino Hydroxypropane tetraacetic acid (DPTA), hydroxyimino disuccinic acid (HIDS) or a salt thereof, etc., and in particular, those having biodegradability such as hydroxyimino disuccinic acid (HIDS) or a salt thereof from the viewpoint of environmental load preferable.

  Alkali metal salts may be mentioned as the type of hydroxyaminocarboxylic acid salt having three or more carboxyl groups used in the cleaning agent for heavy metal-containing aqueous solution of the present invention, and sodium salt or potassium salt because of high solubility and low cost. Is preferred.

  The concentration of the hydroxyaminocarboxylic acid having at least three carboxyl groups used in the cleaning agent for heavy metal-containing aqueous solution of the present invention and / or the salt thereof varies depending on the concentration of magnesium contained in dilution water etc. However, the range of 0.01 to 5% by weight, more preferably 0.02 to 2% by weight, and particularly 0.05 to 1% by weight in the heavy metal treating agent is preferable.

  When the concentration of hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof is lower than 0.01% by weight, sufficient effects can not be obtained when the concentration of magnesium contained in dilution water or the like is high. is there. When the concentration of hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof is higher than 5% by weight, carbodithioate of amine may precipitate.

  The cleaning agent for the heavy metal-containing aqueous solution of the present invention is not particularly limited as long as it contains these three components, but it is preferable to use an aqueous solution from the viewpoint of handling.

  The cleaning agent for a heavy metal-containing aqueous solution of the present invention may contain other components as long as the effects of the present invention are not impaired. As other components, inorganic heavy metal processing agents, pH adjusters, organic solvents, alkali hydroxides and the like can be mentioned.

  Although the amount of dilution water such as fresh water, ground water, industrial water, etc. for diluting the purifying agent for heavy metal-containing aqueous solution is not particularly limited, it is usually 0.1 to the purifying agent for heavy metal-containing aqueous solution. It is used in the range of about 200 times.

  The purification agent for heavy metal-containing aqueous solution of the present invention is particularly useful for purification treatment of a heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper.

  The method of purifying heavy metal-containing aqueous solution according to the present invention removes the generated solid after adding the above-mentioned agent of the present invention to the heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc and cadmium. It is characterized by Here, the generated solid contains heavy metals immobilized by the cleaning agent of the present invention.

  The purification method of the present invention comprises a zinc-containing aqueous solution (for example, a compound capable of forming a complex with zinc and an aqueous solution containing zinc) in which zinc treatment is difficult, a cadmium-containing aqueous solution (for example, cadmium in complex with cadmium) Particularly effective against the compounds having the ability and the aqueous solution containing cadmium.

  The compound having a complexing ability with at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper includes at least one selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper It is not particularly limited as long as it is a compound that forms a complex with heavy metal of For example, a compound having a functional group selected from the group consisting of a carboxyl group and an amino group in the molecule can be mentioned. Specifically, EDTA, polyphosphoric acid and the like can be mentioned, and in particular, EDTA can be mentioned as a compound which forms a strong complex with zinc, cadmium, nickel, mercury, lead and copper.

  The method of adding the salt of dithiocarbamic acid, the polyamine having a weight average molecular weight of 300 or more, the hydroxyaminocarboxylic acid having three or more carboxyl groups and / or the salt thereof to the heavy metal-containing aqueous solution is not particularly limited. Method of separately adding cleaning agents for heavy metal-containing aqueous solution, method of adding pre-mixed drug solution, mixing pre-mixed drug solution with diluted water such as fresh water, ground water, industrial water, etc. The method is mentioned. When the cleaning agents for the heavy metal-containing aqueous solution of the present invention are separately added, the order of addition is not particularly limited.

  The place for diluting the cleaning agent for the heavy metal-containing aqueous solution of the present invention is not particularly limited, and examples thereof include the inside of a tank, the inside of piping, and the like.

  It is preferred to add a flocculant prior to removal of solids in order to facilitate removal of solids. As a coagulant | flocculant, an inorganic coagulant | flocculant and a polymer coagulant | flocculant are mentioned, for example, It is more preferable to use an inorganic coagulant | flocculant and a polymer coagulant | flocculant together.

  As an inorganic coagulant, the inorganic coagulant marketed can be used and it does not specifically limit. Examples include iron compounds such as ferric chloride, and aluminum compounds such as aluminum sulfate and polyaluminum chloride.

  When the heavy metal-containing aqueous solution contains zinc, cadmium, nickel, mercury, lead, and a compound capable of forming a complex with copper, the addition amount of the inorganic coagulant is zinc, cadmium, nickel, mercury, lead contained in the heavy metal-containing aqueous solution It is preferable to make it more than content of the compound which has complexing ability with copper. By making the addition amount of the inorganic coagulant more than the content of zinc, cadmium, nickel, mercury, lead, and the compound having the complexing ability with copper, the cohesiveness is increased, and the zinc concentration and cadmium concentration of the aqueous solution after treatment are increased. It becomes easy to reduce below the drainage standard.

  The content of the compound having the ability to complex with zinc or cadmium in the heavy metal-containing aqueous solution is the concentration of the compound having the ability to complex with zinc or cadmium in the heavy metal-containing aqueous solution, such as HPLC, gas chromatography, titration, etc. It can be calculated by analysis.

  As the polymer flocculant, commercially available polymer flocculants can be used without particular limitation. For example, acrylic acid polymer, acrylamide polymer, dimethylaminoethyl methacrylate polymer and the like can be mentioned. In view of aggregation performance, weak anionic acrylic acid polymers are preferred. The addition of the polymeric flocculant prior to removal of the solids may facilitate handling of the solids to be removed.

  When an inorganic coagulant and a polymer coagulant are used in combination, the order of adding these coagulants is not particularly limited, but it is preferable to add the inorganic coagulant and then add the polymer coagulant.

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

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

  The salts of dithiocarbamic acid used in Examples and Comparative Examples were prepared according to the following method.

(Preparation of salt A of dithiocarbamic acid)
After mixing 112 g of piperazine (manufactured by Tosoh Corporation) and 386 g of pure water, 306 g of 48% by weight potassium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 196 g of carbon disulfide (manufactured by Kishida Chemical Co., It divided into four and was dripped alternately. The mixture was stirred for 1 hour to obtain an aqueous solution containing 40% by weight of the compound represented by the chemical formula (5).

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

(Polyamine)
As polyamines, the following Nippon Shokuhin polyethyleneimines (weight average molecular weight 1800 to 70,000), BASF polyethyleneimines (weight average molecular weight 750,000 to 2,000,000), Huntsman polyether amine, and Tosoh triethylenetetramine used.

  Polyethyleneimine having a weight average molecular weight of 1,800 (hereinafter referred to as PEI (1800)).

  A weight-average molecular weight of 10,000 polyethylenimine (hereinafter referred to as PEI (10,000)).

  Polyethyleneimine having a weight average molecular weight of 70,000 (hereinafter referred to as PEI (70,000)).

  Polyethyleneimine having a weight-average molecular weight of 750,000 (hereinafter referred to as PEI (750,000)).

  Polyethyleneimine having a weight average molecular weight of 2,000,000 (hereinafter referred to as PEI (2,000,000)).

  A weight-average molecular weight 400 product of polyetheramine (grade name: Jeffamine D-400, hereinafter abbreviated as D-400).

  A weight-average molecular weight of 3,000 articles of polyetheramine (grade name, Jeffamine T-3000, hereinafter abbreviated as T-3000).

  Triethylenetetramine (weight average molecular weight 146) (hereinafter abbreviated as EA (146)).

  Hepta ethylene octamine (weight average molecular weight 320) (hereinafter abbreviated as EA (320)).

(Salt of carboxylic acid)
The following was used as the carboxylic acid.

  Tetrasodium hydroxyimino disuccinic acid (HIDS) manufactured by Nagase Chemtex, hydroxyethyl ethylenediamine triacetic acid trisodium (hereinafter abbreviated as HEDTA), diaminohydroxypropane tetraacetic acid (hereinafter abbreviated as DPTA).

  Trisodium citrate, disodium tartrate, tetrasodium ethylenediaminetetraacetate (EDTA) manufactured by Kishda Chemical.

  Methyl glycine diacetate trisodium (MGDA) manufactured by BASF.

  Manufactured by Chelest, trisodium ethylenediaminedisuccinate (EDDS), disodium hydroxyethyl iminodiacetate (HIDA), sodium dihydroxyethylglycine (DHEG).

  Glutamate diacetate tetrasodium (GLDA) manufactured by Showa Denko.

(Inorganic coagulant)
The following aqueous solutions were used as inorganic coagulants.

  An aqueous solution (30% by weight aqueous solution of polyaluminum chloride) obtained by adding 30 g of polyaluminum chloride (PAC) manufactured by Kishida Chemical Co., Ltd. to a total of 100 g.

  38 wt% ferric chloride aqueous solution manufactured by Kishida Chemical.

(Polymer coagulant)
Organo OA-23 (weak anion polymer) was used as a polymer flocculant.

(Analytical method)
The heavy metal ion concentration (for example, zinc ion concentration, cadmium ion concentration, etc.) in the aqueous solution was measured by an ICP emission spectrophotometer (OPTIsMA3300DV, manufactured by Perkin Elmaer).

  The permeability of the aqueous solution mixed with dilution water was measured as an index of the generation of the hardly soluble salt when the prepared drug was mixed with dilution water. That is, the smaller the permeability, the larger the amount of formation of the hardly soluble salt, and the lower the pipe blockage suppression effect. The permeability was calculated from the following equation using a transmission type digital laser sensor (LX2-02, manufactured by Keyence) with a solution prepared by adding 100 mL of 35 mg / L magnesium aqueous solution as dilution water to 10 mL of the prepared drug.

  Transmittance = light receiving amount of aqueous solution after mixing with dilution water (mV) / light receiving amount of pure water (mV) x 100 (%).

Example 1
<Drainage treatment test>
A jar tester (Jar Tester) was placed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. Then, while stirring at 150 rpm, add 400 mg / L of salt A of dithiocarbamic acid, 12 mg / L of PEI (1800) as polyamine, 0.8 mg / L of HIDS as sodium salt of carboxylic acid, and stir at 150 rpm for 10 minutes did. Then, 800 mg / L of a 38 wt% ferric chloride aqueous solution was added, and stirred at 150 rpm for 5 minutes. The pH of the aqueous solution was adjusted to be always pH 7 using a small amount of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with an Advantec 5A filter paper, and the zinc concentration of the treated aqueous solution was measured. The results are shown in Table 1.

Drug dilution test
Drug mixed with dithiocarbamic acid salt A, PEI (1800), HIDS in the same ratio as the drug used in the waste water treatment test (dithiocarbamic acid salt A: PEI (1800): HIDS = 400 The transmittance was measured using 12: 0.8).

Examples 2-3
The wastewater treatment test and the drug dilution test were conducted in the same manner as in Example 1 except that the drug to be added was changed to the drug shown in Table 1. These results are shown together in Table 1.

  As shown in Examples 1 to 3, the zinc concentration of the aqueous solution after treatment was 2.0 mg / L or less which is the drainage standard, and the zinc treatment was sufficient. Moreover, all the transmittance | permeability was 100% and the piping obstruction | occlusion suppression effect was enough.

Comparative Examples 1 to 10
The wastewater treatment test and the drug dilution test were conducted in the same manner as in Example 1 except that the drug to be added was changed to the drug shown in Table 2. These results are shown together in Table 2.

  The comparative example 1 is an example which does not add the salt of carboxylic acid. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. However, the permeability was 80%, and the pipe blockage suppression effect was insufficient.

  Comparative Examples 2 to 4 are examples using hydroxycarboxylic acids outside the scope of the present invention. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. However, the permeability was 82% or less, and the pipe blockage suppression effect was insufficient.

  Comparative Examples 5 to 8 are examples using an aminocarboxylic acid outside the scope of the present invention. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. However, the permeability was 83% or less, and the pipe blockage suppression effect was insufficient.

  Comparative Examples 9 to 10 are examples using hydroxyaminocarboxylic acid outside the scope of the present invention. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. However, the permeability was 82% or less, and the pipe blockage suppression effect was insufficient.

Examples 4 to 10
The wastewater treatment test and the drug dilution test were conducted in the same manner as in Example 1 except that the drug to be added was changed to the drug shown in Table 3. These results are shown together in Table 3.

  Examples 4-9 are the examples which changed and processed the molecular weight of the polyamine within the range of this invention. Regardless of the molecular weight of the polyamine, the zinc concentration of the aqueous solution after treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. Moreover, all the transmittance | permeability was 100% and the piping obstruction | occlusion suppression effect was enough.

  Example 10 is an example using the salt B of dithiocarbamic acid instead of the salt A of dithiocarbamic acid. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the zinc treatment was sufficient. Moreover, the transmittance | permeability was 100% and the piping obstruction | occlusion suppression effect was enough.

Comparative example 11
A jar tester (Jar Tester) was placed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. Then, while stirring at 150 rpm, 800 mg / L of a 38 wt% ferric chloride aqueous solution was added, and stirred at 150 rpm for 10 minutes. The pH of the aqueous solution was adjusted to be always pH 10 using a trace amount of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with an Advantec 5A filter paper, and the zinc concentration of the treated aqueous solution was measured. The results are shown in Table 4.

Comparative Examples 12 to 16
The wastewater treatment test and the drug dilution test were conducted in the same manner as in Example 1 except that the drug to be added was changed to the drug shown in Table 4. These results are shown together in Table 4.

  Comparative Example 11 is an example of a conventional treatment method in which iron ions are added for neutralization, and zinc ions are precipitated together with iron ions as hydroxides. The zinc concentration of the aqueous solution after treatment was 4.3 mg / L, which exceeded the 2 mg / L drainage standard, and the zinc treatment was insufficient.

  Comparative Examples 12 to 14 are examples in which only the salt A of dithiocarbamic acid was treated without adding a polyamine. The zinc concentration of the aqueous solution after the treatment exceeded 2 mg / L, which is the drainage standard, and the zinc treatment was insufficient.

  Comparative Example 15 is an example in which only PEI (1800) as a polyamine was added without addition of the salt A of dithiocarbamic acid, and then an inorganic flocculant was added and treated at pH 7. The zinc concentration of the aqueous solution after the treatment exceeded 2 mg / L, which is the drainage standard, and the zinc treatment was insufficient.

  Comparative Example 16 is an example in which a polyamine of weight average molecular weight 146 outside the scope of the present invention and salt A of dithiocarbamic acid are used in combination, but the zinc concentration of the aqueous solution after treatment exceeds 2 mg / L, which is the drainage standard. Treatment of zinc was insufficient.

Examples 11 to 14 and Comparative Examples 17 to 18
The wastewater treatment test and the drug dilution test were conducted in the same manner as in Example 1 except that the drug to be added was changed to the drug shown in Table 5. These results are shown together in Table 5.

  Examples 11-14 are the examples which changed and processed the weight part of the polyamine (PEI (1800)) with respect to 100 weight parts of the salt of dithio carbamic acid within the range of this invention. The zinc concentration of the aqueous solution after treatment was 2 mg / L or less, which is the drainage standard, regardless of the amount of polyamine added, and the zinc treatment was sufficient. Moreover, all the transmittance | permeability was 100% and the piping obstruction | occlusion suppression effect was enough.

  The comparative example 17 is an example which added the salt A of dithio carbamic acid, and PEI (1800) of the quantity below the scope of the present invention. The zinc concentration of the aqueous solution after the treatment exceeded 2 mg / L, which is the drainage standard, and the zinc treatment was insufficient.

  Comparative Example 18 is an example in which salt A of dithiocarbamic acid and PEI (1800) in an amount exceeding the range of the present invention were added. The zinc concentration of the aqueous solution after treatment was 6.0 mg / L, and the zinc treatment performance was significantly deteriorated.

  From Comparative Example 17 and Comparative Example 18, it is understood that the amount of polyamine used in combination with the salt of dithiocarbamic acid has a suitable range in which zinc can be treated.

Example 15
A jar tester (Jar Tester) was placed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. Then, while stirring at 150 rpm, 400 mg / L of salt A of dithiocarbamic acid, 12 mg / L of PEI (1800) as polyamine, 0.8 mg / L of HIDS as a salt of carboxylic acid were added and stirred at 150 rpm for 10 minutes . Then, 800 mg / L of a 38 wt% ferric chloride aqueous solution was added, and stirred at 150 rpm for 5 minutes. Subsequently, 2000 mg / L of 0.1 weight% OA-23 aqueous solution was added as a polymer flocculant, adjusted to pH 7, and stirred at 50 rpm for 5 minutes. The pH of the aqueous solution was adjusted to be always pH 7 using a small amount of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with an Advantec 5A filter paper, and the zinc concentration of the treated aqueous solution was measured. The results are shown in Table 6.

Example 16
The zinc concentration of the aqueous solution after treatment was measured in the same manner as in Example 15, except that the drug to be added was changed to the drug shown in Table 6. These results are shown together in Table 6.

Example 17
A solution containing 200 mg of dithiocarbamic acid salt A, 6 mg of PEI (1800) and 0.4 mg of HIDS was mixed with 2 mL of dilution water containing 35 mg / L of Mg to prepare a drug dilution.
A jar tester (Jar Tester) was placed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of zinc ions and 260 mg / L of EDTA was added. Next, while stirring at 150 rpm, the whole drug dilution was added and stirred at 150 rpm for 10 minutes. Then, 800 mg / L of a 38 wt% ferric chloride aqueous solution was added, and stirred at 150 rpm for 5 minutes. The pH of the aqueous solution was adjusted to be always pH 7 using a small amount of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with an Advantec 5A filter paper, and the zinc concentration of the treated aqueous solution was measured. The results are shown in Table 6 together.

  Example 15 is an example in which a polymer flocculant is added to Example 1. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, at the same value as when the polymer coagulant was not added, and the zinc treatment was sufficient.

  Example 16 is an example using PAC aqueous solution as an inorganic coagulant. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, and the treatment of zinc was sufficient regardless of the type of inorganic flocculant.

  Example 17 is an example in which the drug used in Example 1 was diluted with dilution water and then added to a zinc-containing solution for treatment. The zinc concentration of the aqueous solution after the treatment was 2.0 mg / L or less, which is the drainage standard, which was the same value as when the drug was not diluted with dilution water, and the zinc treatment was sufficient.

Example 18
A jar tester (Jar Tester) was placed in a 500 mL beaker, and 500 mL of an aqueous solution containing 10 mg / L of cadmium ion and 260 mg / L of EDTA was added. Then, while stirring at 150 rpm, add 400 mg / L of salt A of dithiocarbamic acid, 12 mg / L of PEI (1800) as polyamine, 0.8 mg / L of HIDS as sodium salt of carboxylic acid, and stir at 150 rpm for 10 minutes did. Then, 800 mg / L of a 38 wt% ferric chloride aqueous solution was added, and stirred at 150 rpm for 5 minutes. The pH of the aqueous solution was adjusted to be always pH 7 using a small amount of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with a 5A filter paper made by Advantec, and the cadmium concentration of the aqueous solution after treatment was measured. The results are shown in Table 7.

Examples 19 to 21
The concentration of heavy metal in the aqueous solution after treatment was measured in the same manner as in Example 18 except that the compound having the ability to form a complex with heavy metal, the aqueous solution containing heavy metal, and the drug to be added were changed to those shown in Table 7. These results are shown together in Table 7.

  Examples 18 to 21 are the examples in which the heavy metal-containing waste water was treated by adding the agent of the present invention in the case of cadmium, mercury, and nickel. As apparent from Table 7, the cadmium concentration and the mercury concentration of the aqueous solution after the treatment can be treated so as to be 0.03 mg / L or less of cadmium and 0.005 mg / L or less of mercury respectively as the drainage standard value, and nickel is 4.6 mg / L. It could be reduced to L.

Example 22
A jar tester (Jar Tester) was installed in a 500 mL beaker, and 500 mL of desulfurization waste water from a coal-fired power plant was added. Next, while stirring at 150 rpm, 9.7 mg / L of dithiocarbamic acid salt A, 0.3 mg / l of PEI (10,000) as polyamine and 0.02 mg / L of HIDS were added, and stirred at 150 rpm for 10 minutes. Then, 1000 mg / L of a 30% by weight aqueous solution of polyaluminum chloride was added, and the mixture was stirred at 150 rpm for 5 minutes. Subsequently, 2000 mg / L of 0.1 weight% OA-23 aqueous solution was added as a polymer flocculating agent, and it stirred for 5 minutes by 50 rpm. The pH of the aqueous solution was adjusted to be always pH 7 using trace amounts of hydrochloric acid and sodium hydroxide. After completion of the stirring, the solution was allowed to stand for 10 minutes, the aqueous solution was filtered off with a filter paper made by Advantec 5A, and the heavy metal concentration of the aqueous solution after treatment was measured. The results are shown in Table 8.

Example 23
The heavy metal concentration of the aqueous solution after treatment was measured in the same manner as in Example 22 except that desulfurization drainage of a coal thermal power plant was changed to desulfurization drainage shown in Table 8. The results are shown in Table 8 together.

  Examples 22-23 are the examples which added and processed the chemical | medical agent in the range of this invention in the desulfurization waste water of a coal-fired power plant. The zinc concentration of the aqueous solution after treatment was less than 0.1 mg / L, and the cadmium concentration was less than 0.03 mg / L, and other heavy metals could also be treated below the drainage standard. That is, it has been confirmed that the purification agent of the present invention is also effective for purification of actual wastewater containing heavy metals.

  According to the method of purifying heavy metal-containing aqueous solution of the present invention, it is difficult to treat heavy metals such as zinc and cadmium, aqueous solution containing heavy metal such as zinc and cadmium, and compounds having complexing ability, and heavy metals such as zinc and cadmium Even if the heavy metal concentration can be reduced, it is used as a novel purification method of heavy metal-containing aqueous solution for the treatment of wastewater containing heavy metals such as zinc and cadmium from plating plants, electronic parts and machine parts manufacturing plants, and automobile plants. Have the potential to

Claims (13)

A cleaning agent for a heavy metal-containing aqueous solution, comprising 2 to 50 parts by weight of a polyamine having a weight average molecular weight of 300 or more, and hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof relative to 100 parts by weight of a dithiocarbamic acid salt. The salt of dithiocarbamic acid is a reaction product of an amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group, carbon disulfide and an alkali metal hydroxide The purification agent for a heavy metal-containing aqueous solution according to claim 1, characterized in that The dithiocarbamic acid salt is a reaction product of an amine compound having two or more amino groups selected from the group consisting of a primary amino group and a secondary amino group, carbon disulfide and an alkali metal hydroxide The purification agent for a heavy metal-containing aqueous solution according to claim 1, characterized in that The cleaning agent for a heavy metal-containing aqueous solution according to claim 1, wherein the dithiocarbamic acid salt is a reaction product of piperazine or tetraethylene pentamine, carbon disulfide and an alkali metal hydroxide. The cleaning agent for a heavy metal-containing aqueous solution according to any one of claims 1 to 4, wherein the polyamine having a weight average molecular weight of 300 or more is a polyethyleneimine having a weight average molecular weight of 300 or more. The cleaning agent for a heavy metal-containing aqueous solution according to any one of claims 1 to 4, wherein the polyamine having a weight average molecular weight of 300 or more is a polyethyleneimine having a weight average molecular weight of 1,800 to 200,000. The heavy metal-containing aqueous solution according to any one of claims 1 to 6 is added to a heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper, What is claimed is: 1. A method of purifying a heavy metal-containing aqueous solution, comprising removing a generated solid. The heavy metal-containing aqueous solution containing at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper is added with the purification agent for heavy metal-containing aqueous solution according to any one of claims 1 to 6 and dilution water The method of purifying a heavy metal-containing aqueous solution is characterized by removing the solid matter generated after the 9. The heavy metal-containing aqueous solution according to claim 7, further comprising a compound having an ability to form a complex with at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper. Of purification of heavy metal-containing aqueous solution. A compound having the ability to form a complex with at least one heavy metal selected from the group consisting of zinc, cadmium, nickel, mercury, lead and copper is a compound having in its molecule a functional group selected from the group consisting of a carboxyl group and an amino group 10. The method for purifying a heavy metal-containing aqueous solution according to claim 9, wherein An inorganic coagulant | flocculant is added before removing a solid substance, The purification method of the heavy metal containing aqueous solution in any one of the Claims 7-10 characterized by the above-mentioned. An inorganic coagulant | flocculant and a polymer coagulant | flocculant are added before removing a solid substance, The purification method of the heavy metal containing aqueous solution in any one of the Claims 7-10 characterized by the above-mentioned. The method for purifying a heavy metal-containing aqueous solution according to claim 11 or 12, wherein the inorganic coagulant is selected from the group consisting of an iron compound and an aluminum compound.