JP6048071B2 - Heavy metal treating agent and method for treating heavy metal contaminants - Google Patents

Description

  The present invention relates to heavy metal pollutants, for example, incinerated ash and fly ash discharged from garbage incinerators, soil contaminated with heavy metals, sludge generated after wastewater treatment, lead contained in wastewater discharged from factories, zinc, etc. , Cadmium, mercury, arsenic, selenium, chromium and other heavy metal treatment agents that can easily fix and elute harmful heavy metals, such as drinking water, groundwater, industrial water, etc. The present invention provides a heavy metal treating agent and a method for treating heavy metal contaminants that can suppress blockage of pipes, strainers and the like even during mixed use.

  Fly ash discharged from municipal waste incineration plants and the like has a high heavy metal content and needs to be treated to suppress elution of heavy metals. As one of such treatment methods, there is a chemical treatment method, and a method of insolubilizing heavy metals by adding a heavy metal treatment agent such as a chelate-based chemical is used.

  As the chelating agent, amine carbodithioate is mainly used. In particular, piperazine carbodithioate is widely used as a heavy metal treating agent because it generates less harmful gases such as hydrogen sulfide and carbon disulfide compared to other amine carbodithioates (see, for example, Patent Document 1). ).

  As a method of using chelating chemicals, when water and chelating chemicals are added directly to heavy metal pollutants separately, after diluting and mixing the chemicals to a predetermined concentration with dilution water such as clean water, groundwater, industrial water, etc. Added to heavy metal contaminants.

  When diluting and mixing a killer chemical to a predetermined concentration with dilution water such as tap water, groundwater, and industrial water, and adding it to heavy metal contaminants, the dilution water contains various inorganic substances such as magnesium, calcium, silicon, and iron. There is a problem that the inorganic substance in the diluted water precipitates as a hardly soluble salt by mixing the diluted water and the chelating agent, causing the piping and the nozzle to be blocked.

  For this problem, it is known that clogging is suppressed by adding aminocarboxylic acids to the dilution water as a scale inhibitor (see, for example, Patent Document 2).

  However, such a method does not always have a sufficient effect of suppressing the blockage of pipes and strainers.

Japanese Patent No. 3391173 JP 2002-166247 A

  An object of the present invention is to provide a heavy metal treating agent capable of suppressing clogging of pipes and strainers and the like and a method for treating heavy metal contaminants using the same even when mixed with diluted water or the like.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors are mainly caused by magnesium ions in dilute water, and a hydroxyaminocarboxylic acid having 3 or more carbodithioates of amines and carboxyl groups. Even when mixed with dilution water such as clean water, groundwater, industrial water, etc., magnesium ions in the dilution water precipitate as a sparingly soluble salt by using a heavy metal treating agent containing a salt thereof. The present inventors have found that heavy metals can be insolubilized without suppressing this and without causing blockage of piping, strainers, etc., and the present invention has been completed.

  Hereinafter, the present invention will be described in detail.

  The heavy metal treating agent of the present invention comprises an amine carbodithioate and a hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof.

  By using a heavy metal treating agent comprising a carbodithioate of amine and a hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof, mixing with dilution water such as clean water, groundwater, industrial water, etc. Even when it is carried out, it is possible to suppress the precipitation of magnesium ions in diluted water as a hardly soluble salt, and to insolubilize heavy metals without causing clogging of pipes and strainers.

  In the case of an aminocarboxylic acid which is a conventional scale inhibitor, when combined with a carbodithioate of an amine, the effect thereof is insufficient, and a hydroxyaminocarboxylic acid having 2 or less carboxyl groups and / or a salt thereof. Then, the effect equivalent to this invention cannot be acquired.

  The reason why hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof is effective in preventing clogging of piping etc. in combination with carbodithioate of amine is not clear, but 3 or more carboxyl groups The hydroxyaminocarboxylic acid and / or salt thereof has a tendency to form a water-soluble complex with magnesium, compared to conventional aminocarboxylic acid and hydroxyaminocarboxylic acid having 2 or less carboxyl groups and / or salt thereof, and Since the solubility of the water-soluble complex is high, it is considered that the magnesium ion can be effectively prevented from being precipitated as a poorly soluble salt even in the presence of an amine carbodithioate.

  A heavy metal treating agent comprising a carbodithioate of amine and a hydroxyaminocarboxylic acid having three or more carboxyl groups and / or a salt thereof is not only magnesium but also an aminocarboxylic acid which is a conventional scale inhibitor. The same effect is shown in effective calcium.

  The amine carbodithioate used in the heavy metal treating agent of the present invention is not particularly limited, and examples thereof include carbodithioate derived from linear and cyclic aliphatic or aromatic amine compounds. Examples of the aliphatic amine compound include diethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, pyrrolidine, piperazine and the like. Moreover, aniline etc. are illustrated as an aromatic amine compound. In particular, piperazine carbodithioate having high stability to heat and pH is preferred. Specific examples of piperazine carbodithioate include piperazine-N-monocarbodithioate and piperazine-N, N′-biscarbodithioate.

  The type of amine carbodithioate salt used in the heavy metal treating agent of the present invention is not particularly limited, and examples thereof include alkali metal salts, alkaline earth metal salts, ammonium salts, and the like. Sodium salt or potassium salt is preferred because of its low cost.

  When the heavy metal treating agent of the present invention is used in an aqueous solution, the concentration of the amine carbodithioate is preferably 10 to 60% by weight, particularly preferably 30 to 50% by weight. If the concentration is higher than 60% by weight, carbodithioate of amine may be precipitated. Moreover, when a density | concentration is lower than 10 weight%, heavy metal processing capacity will fall.

  The hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof used in the heavy metal treating agent of the present invention is not particularly limited, but is hydroxyethylethylenediaminetriacetic acid (HEDTA), diaminohydroxypropanetetraacetic acid. (DPTA), hydroxyiminodisuccinic acid (HIDS) or a salt thereof, and the like, and those having biodegradability such as hydroxyiminodisuccinic acid (HIDS) or a salt thereof are particularly preferable from the viewpoint of environmental load.

  Examples of the salt of hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof used in the heavy metal treating agent of the present invention include alkali metal salts, especially sodium salt or potassium because of its high solubility and low cost. Salts are preferred.

  Since the concentration of the hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or its salt used in the heavy metal treating agent of the present invention varies depending on the concentration of magnesium contained in the dilution water, etc., it cannot be generally determined. However, the range of 0.01 to 5% by weight, more preferably 0.02 to 2% by weight, particularly 0.05 to 1% by weight in the heavy metal treating agent is preferred.

  When the concentration of hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof is lower than 0.01% by weight, sufficient effect may not be obtained if the concentration of magnesium contained in the dilution water is high. is there. When the concentration of hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof is higher than 5% by weight, carbodithioate of amine may be precipitated.

  The heavy metal treating agent of the present invention is not particularly limited as long as it contains these two components, but is preferably used in an aqueous solution from the viewpoint of handling.

  The heavy metal treating agent of the present invention may contain other components as long as the effects of the present invention are not hindered. Examples of other components include inorganic heavy metal treating agents, pH adjusters, organic solvents, and alkali hydroxides.

  The method for treating heavy metal contaminants using the heavy metal treating agent of the present invention is not particularly limited, and after mixing the heavy metal treating agent of the present invention with dilution water such as tap water, ground water, industrial water, etc. Add to the material and mix.

  The place for diluting the heavy metal treating agent of the present invention is not particularly limited, and examples thereof include the inside of a tank and piping.

  The amount of dilution water such as clean water, groundwater, industrial water for diluting the heavy metal treatment agent is not particularly limited, but is usually used in a range of about 0.1 to 200 times that of the heavy metal treatment agent. The

  The amount of heavy metal treating agent used varies depending on the state of heavy metal contaminants, the content of heavy metals and the form of heavy metals, but is usually used in the range of 0.01 to 30% by weight, for example, for fly ash. In order to facilitate the treatment, 1 to 20% by weight of humidified water may be separately added to the heavy metal contaminant during kneading.

  The heavy metal treating agent of the present invention can be used for treatment of fly ash, soil, sludge, waste water, sludge and the like as heavy metal contaminants.

  Examples of harmful heavy metals in these heavy metal pollutants include lead, zinc, cadmium, mercury, arsenic, selenium, and chromium.

  The heavy metal treating agent of the present invention can insolubilize heavy metals without causing clogging of piping, strainers, etc. even when mixed with dilution water such as clean water, groundwater, and industrial water.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

(Dilute test of heavy metal treatment agent)
Reference example 1
150 g of pure water was collected in a 200 mL beaker, and while stirring, the permeability of the solution was measured with LX2-02T (manufactured by Keyence Corporation), and LX2-60 (manufactured by Keyence Corporation) was measured. The value output in mV was read. To this was added 15 g of piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution, the permeability after 10 minutes was measured, and the change in permeability was calculated by subtracting the initial permeability from the permeability. As a result, it was +48 mV, and since the decrease in permeability was not observed, formation of hardly soluble salts was not confirmed, and formation of hardly soluble salts was not observed visually.

Reference example 2
The same operation as in Reference Example 1 was performed except that the pure water was changed to an aqueous solution containing 10 ppm of Mg.

  The change in permeability was -160 mV, and the presence of Mg produced a poorly soluble salt, confirming a decrease in permeability, and the formation of a poorly soluble salt was also observed visually.

Example 1
To 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate, tetrasodium 3-hydroxy-2,2′-iminodisuccinate (HIDS) (hydroxyaminocarboxylate having four carboxyl groups) was added to 0.1 g. 1g was added and the heavy metal processing agent A was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent A. The change in permeability is +45 mV, which is the same change as in the pure water of Reference Example 1. Since the decrease in permeability was not observed, the formation of hardly soluble salts was not confirmed, and formation of hardly soluble salts was also visually observed. Was not observed.

Example 2
0.1 g of trisodium hydroxyethylethylenediamine triacetate (HEDTA) (hydroxyaminocarboxylate having three carboxyl groups) is added to 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate, and treated with heavy metal. Agent B was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent B. The change in permeability is +45 mV, which is the same change as in the pure water of Reference Example 1. Since the decrease in permeability was not observed, the formation of hardly soluble salts was not confirmed, and formation of hardly soluble salts was also visually observed. Was not observed.

Example 3
0.1 g of 1,3-diamino-2-hydroxypropanetetraacetic acid (DPTA) (hydroxyaminocarboxylate having four carboxyl groups) is added to 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%. And a heavy metal treating agent C was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent C. The change in the permeability is +53 mV, which is the same change as in the pure water of Reference Example 1. Since the decrease in the permeability was not observed, the formation of the hardly soluble salt was not confirmed, and the formation of the hardly soluble salt was visually confirmed. Was not observed.

Example 4
The same operation as in Example 1 was performed except that the aqueous solution containing 10 ppm of Mg was changed to industrial water (containing Mg = 4.0 ppm and Ca = 8.5 ppm). The change in the permeability is +50 mV, which is the same change as that in the pure water of Reference Example 1. Since the decrease in the permeability was not observed, the formation of the hardly soluble salt was not confirmed, and the formation of the hardly soluble salt was visually confirmed. Was not observed.

Comparative Example 1
A heavy metal treating agent D was prepared by adding 0.1 g of sodium gluconate (hydroxycarboxylate having one carboxyl group) to 100 g of aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent D. The change in permeability was -360 mV, and the permeability decreased, so formation of a hardly soluble salt was confirmed, and formation of a hardly soluble salt was also observed visually.

Comparative Example 2
A heavy metal treating agent E was prepared by adding 0.1 g of trisodium citrate (hydroxycarboxylate having three carboxyl groups) to 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent E. The change in permeability was −115 mV, and the permeability decreased, so the formation of a hardly soluble salt was confirmed, and the formation of a hardly soluble salt was also observed visually.

Comparative Example 3
A heavy metal treating agent F was prepared by adding 0.1 g of disodium tartrate (hydroxycarboxylate having two carboxyl groups) to 100 g of an aqueous solution of potassium piperazine-N, N′-biscarbodithioate 40 wt%.

  The same operation as in Reference Example 2 was carried out except that the aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt% was changed to the heavy metal treating agent F. The change in permeability was -330 mV, and the permeability decreased, so formation of a hardly soluble salt was confirmed, and formation of a hardly soluble salt was also observed visually.

Comparative Example 4
0.1 g of trisodium ethylenediamine disuccinate (EDDS) (aminocarboxylate having four carboxyl groups) is added to 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%. Was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent G. Although the change in the permeability is -5 mV and there is an effect of suppressing the formation of the hardly soluble salt, the permeability is reduced compared to +48 mV in the pure water of Reference Example 1, and the formation of the hardly soluble salt is confirmed. In addition, formation of a hardly soluble salt could be observed visually, and the effect was insufficient.

Comparative Example 5
To 100 g of piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution, 0.1 g of glutamic acid tetrasodium acetate (GLDA) (aminocarboxylate having four carboxyl groups) was added, and heavy metal treating agent H was added. Prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate potassium 40 wt% aqueous solution was changed to the heavy metal treating agent H. Although the change in permeability is -28 mV, which has the effect of suppressing the formation of sparingly soluble salts, the permeability is reduced as compared to +48 mV in the pure water of Reference Example 1, confirming the formation of sparingly soluble salts. In addition, formation of a hardly soluble salt could be observed visually, and the effect was insufficient.

Comparative Example 6
0.1 g of trisodium methylglycine diacetate (MGDA) (aminocarboxylate having three carboxyl groups) is added to 100 g of 40% by weight aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%, and the heavy metal treating agent I Was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent I. Although the change in the permeability is -10 mV, and there is an effect of suppressing the formation of the hardly soluble salt, the permeability is reduced as compared with +48 mV in the pure water of Reference Example 1, and the formation of the hardly soluble salt is confirmed. In addition, formation of a hardly soluble salt could be observed visually, and the effect was insufficient.

Comparative Example 7
0.1 g of ethylenediaminetetraacetic acid tetrasodium (EDTA) (an aminocarboxylate having four carboxyl groups) is added to 100 g of aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt%, and heavy metal treating agent J is added. Prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioic acid 40 wt% aqueous solution was changed to the heavy metal treating agent J. The change in permeability is 0 mV, and although there is an effect of suppressing the production of hardly soluble salt, the permeability is reduced compared to +48 mV in pure water of Reference Example 1, and the formation of a hardly soluble salt was confirmed. Moreover, the formation of a hardly soluble salt could be observed visually, and the effect was insufficient.

Comparative Example 8
0.1 g of disodium hydroxyethyliminodiacetate (HIDA) (hydroxyaminocarboxylate having two carboxyl groups) is added to 100 g of aqueous solution of piperazine-N, N′-biscarbodithioate 40 wt% to treat with heavy metal Agent K was prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution was changed to the heavy metal treating agent K. The change in permeability was −150 mV, and the permeability decreased, so formation of a hardly soluble salt was confirmed, and formation of a hardly soluble salt was also observed visually.

Comparative Example 9
To 100 g of piperazine-N, N′-biscarbodithioate 40 wt% aqueous solution, 0.1 g of dihydroxyethylglycine sodium (DHEG) (hydroxyaminocarboxylate having one carboxyl group) was added, and heavy metal treating agent L was added. Prepared.

  The same operation as in Reference Example 2 was performed except that the piperazine-N, N′-biscarbodithioate potassium 40 wt% aqueous solution was changed to the heavy metal treating agent L. The change in permeability was −117 mV, and the permeability decreased, so formation of a hardly soluble salt was confirmed, and formation of a hardly soluble salt was also observed visually.

（処理能力試験）
実施例５
重金属処理剤Ａ１０ｇとＭｇを１０ｐｐｍ含有する希釈水１００ｇを混合し、薬剤希釈液Ａを調製した。

(Processing capacity test)
Example 5
10 g of heavy metal treating agent A and 100 g of diluted water containing 10 ppm of Mg were mixed to prepare a drug diluent A.

  Add 16.5 g of Drug Diluent A to 50 g of fly ash containing Pb = 2500 mg / kg and Cu = 715 mg / kg, and after mixing, perform the Environmental Agency Notification No. 13 test to determine the heavy metal concentration in the eluate. It was measured. Pb could be processed below the elution standard value (0.3 mg / L).

Example 6
The same operation as in Example 5 was performed except that the heavy metal treatment agent A was changed to the heavy metal treatment agent B. Pb could be processed below the elution standard value (0.3 mg / L).

Example 7
The same operation as in Example 5 was performed except that the heavy metal treating agent A was changed to the heavy metal treating agent C. Pb could be processed below the elution standard value (0.3 mg / L).

  The heavy metal treating agent of the present invention is used for detoxifying heavy metals contained in fly ash, soil, sludge, drainage, sludge and the like.

Claims (5)

A heavy metal treating agent comprising a carbodithioate of an amine and a hydroxyaminocarboxylic acid having 3 or more carboxyl groups and / or a salt thereof. The heavy metal treating agent according to claim 1, wherein the carbodithioate of amine is a carbodithioate of piperazine. A method for treating heavy metal contaminants, comprising mixing the heavy metal treating agent according to claim 1 or 2 with dilution water and then adding the mixture to the heavy metal contaminants. The heavy metal pollutant treatment method according to claim 3, wherein the heavy metal pollutant is fly ash, soil, sludge, drainage, or sludge. The method for treating a heavy metal contaminant according to claim 3 or 4, wherein the heavy metal in the heavy metal contaminant is lead, zinc, cadmium, mercury, arsenic, selenium, or chromium.