JP5439990B2 - Solid heavy metal treating agent, production method and use thereof - Google Patents

Description

The present invention is a solid heavy metal that is excellent in transportation economy, storage stability (stable active ingredient concentration, anti-caking), safety in use (no harmful gas generation), and excellent reaction selectivity for harmful lead. A treatment agent is provided.

  Amine carbodithioate is used as an immobilizing agent for heavy metals such as fly ash, soil and wastewater. As the carbodithioate of amine as a heavy metal treating agent, an aqueous solution of about 30 to 60% is usually used, but recently, the demand for a solid (powdered) heavy metal treating agent is increasing.

  So far, solid heavy metal treating agents containing amine carbodithioate in solid excipients have been proposed. For example, a method of using 100 parts by weight of alkali hydroxide or alkaline earth hydroxide with respect to 3 to 30 parts by weight of carbodithioate (Patent Document 1), a method using calcium silicate as a carrier (Patent Document 2), A method using a carbodithioate of an insoluble transition metal (Patent Document 3), a method using a spray-dried carbodithioate solution at a high temperature (Patent Document 4), and a starch containing a chelating agent in powder form (Patent Document 5) and the like.

  However, conventional solid heavy metal treating agents have only a low active ingredient concentration in the solid. Further, when an insoluble carbodithioate salt is dispersed in water and used as a slurry when a conventional heavy metal treating agent in an aqueous solution is used, there is a problem that it is difficult to use due to clogging of piping and the like. In the method of obtaining a solid heavy metal treating agent by concentration or spray drying, a large amount of energy is required for evaporation of the aqueous solution, which is not economical. In order to avoid energy consumption in removing the solvent, the method in which the carbodithioate is included in the excipient has a problem that the performance of the drug per unit weight is low because the ratio of the formation in the heavy metal treatment agent is large. It was.

  On the other hand, piperazine-N, N′-biscarbodithioate is known as an excellent heavy metal treatment agent having high heavy metal treatment ability and no generation of harmful gas (see Patent Document 6). Conventional fly ash treatment using piperazine-N, N'-biscarbodithioate as an active ingredient has only been used as an aqueous solution of piperazine-N, N'-biscarbodithioate.

  Solid piperazine-N, N′-biscarbodithioate is an anhydrous form of piperazine-N, N′-biscarbodithioic acid sodium salt (solid) obtained by recrystallization in an organic solvent. Japanese hydrate (or 4.5 hydrate) or hexahydrate is only known as a reagent used for colorimetric analysis of trace metals and has not been used as a heavy metal treating agent (Non-patent Document) 1-4).

Japanese Patent No. 3895018 JP 2004-97927 A JP2003-301165A JP 2003-336035 A JP 2003-113362 A Japanese Patent No. 3391173

Meiji University research report No. 67, pp. 23-30 (1985) Meiji University research report No. 67, pp. 31-36 (1985) Spectrochemica Acta, Vol. 40A, pp 343-346, (1984) CHEMICA ANALYTYCZNA, Vol. 10, p837-844, (1965)

  The object of the present invention is excellent in transportation economical efficiency, no change in active ingredient concentration during storage, no caking, excellent storage stability, no generation of harmful gases during storage and use, and against harmful lead The object is to provide a heavy metal treating agent with high selectivity.

  As a result of intensive studies on a solid heavy metal treating agent excellent in heavy metal treating ability and handleability (economic efficiency, storage stability, safety), the present inventors have conducted piperazine-N, N′-biscarbodithio. Potassium acid dihydrate has high crystallinity not found in other forms of hydrates or hydrates of the salt, and contains heavy metals without problems of weight change and consolidation during storage. It has been found that the generation of harmful gases such as carbon disulfide can be reduced to the utmost when it is used in direct mixing, and the reaction selectivity for particularly harmful lead is improved, and the present invention has been completed. is there.

  The heavy metal treating agent comprising piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention will be described below.

  The heavy metal treating agent comprising piperazine-N, N'-biscarbodithioate potassium dihydrate of the present invention is particularly preferably one having high crystallinity having the following main X-ray diffraction peaks.

高い結晶性を有するピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウム・２水和物では、大気中の保存において有効成分（ピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウム）の含有量に変動がなく、保存中に固結し難いという特徴を有する。

Piperazine-N, N'-biscarbodithioate potassium dihydrate, which has high crystallinity, varies in content of active ingredient (piperazine-N, N'-biscarbodithioate potassium) during storage in the atmosphere And has the feature that it is difficult to consolidate during storage.

  Piperazine-N, N'-biscarbodithioic acid anhydrate absorbs moisture in the atmosphere and changes the weight ratio of the active ingredient in the heavy metal treatment agent. However, in the piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention, there is no change in weight due to the absorption of moisture in the atmosphere, so that there is no need for such confirmation.

  The heavy metal treating agent containing potassium piperazine-N, N′-biscarbodithioate dihydrate of the present invention as an active ingredient has a content of potassium piperazine-N, N′-biscarbodithioate of 85% by weight or more. It is preferable that When the crystal powder of the heavy metal treating agent is all dihydrate, the content of piperazine-N, N′-biscarbodithioate potassium is 89.7% by weight. Piperazine-N, N'-biscarbodithioate potassium dihydrate is not a mixture of amine carbodithioate with other solid salt (carrier) like conventional solid heavy metal treating agent. Since it is a pure crystal | crystallization, the content rate of the active ingredient in a heavy metal processing agent is high. In the present invention, even if anhydrous or low hydrate is partially contained in the dihydrate crystal, at least the surface portion of the particle is composed of dihydrate to prevent caking. The effect can be demonstrated.

  The heavy metal treating agent comprising piperazine-N, N′-biscarbodithioic acid potassium dihydrate of the present invention generates noxious gases during storage of the drug and when mixed with heavy metal-containing materials. There is nothing. Solid potassium potassium piperazine-N, N'-biscarbodithioate generates carbon disulfide in the anhydride, but there is no such problem in the dihydrate.

  Furthermore, the heavy metal treating agent comprising piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention has high reaction selectivity to harmful lead and efficiently fixes harmful lead. It can be processed. For example, piperazine-N, N'-biscarbodithioate potassium dihydrate reaction selectivity to lead (compared to copper) in heavy metal treatment of heavy metal-containing materials is the water content of total solids (fly ash + chelating agent) When the addition amount is about 20% by weight, it is five times higher than the anhydrous product. Even when the amount of water added is increased, the superiority of the reaction selectivity of dihydrate to lead is maintained.

  The amount of water added to the total solid content of the heavy metal-containing material and heavy metal treatment agent in the heavy metal treatment using the heavy metal treatment agent of the present invention is not particularly limited, but is preferably 10% by weight to 50% by weight, particularly preferably 20% by weight or more. It is preferably 40% by weight or less. For example, in the treatment of heavy metal-containing fly ash, if the amount of water added is too large, it becomes a huge lump or slurry and it becomes difficult to handle the treated ash, so the amount of water added is usually 20 to 40% by weight based on the solid content. It is performed to be in the range. Therefore, the heavy metal treating agent comprising the piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention exhibits a high reaction selectivity to lead in the fly ash treatment with a normal water addition amount. can do.

  The heavy metal treating agent of the present invention may further contain an alkali hydroxide or an alkaline earth hydroxide for improving the stability. Since these alkali components are not used as excipients, their content is 0.01 to 5% by weight, particularly 0.1 to 2% by weight, based on piperazine-N, N′-biscarbodithioate potassium. A range of is sufficient. As the alkali hydroxide, sodium hydroxide and potassium hydroxide are preferable, and as the alkaline earth hydroxide, magnesium hydroxide and calcium hydroxide are preferable.

  Although the manufacturing method of the piperazine-N, N'-biscarbodithioic acid potassium dihydrate of this invention is not specifically limited, It can manufacture efficiently with the following manufacturing methods.

  Piperazine-N, N'-biscarbodithioate potassium dihydrate is prepared by reacting piperazine, carbon disulfide and potassium hydroxide in a saturated aqueous solution of piperazine-N, N'-biscarbodithioate potassium. -N, N'-biscarbodithioic acid potassium salt can be precipitated and the salt can be separated from the aqueous solution.

  Piperazine and piperazine-N, N′-biscarbodithioate have higher solubility in water than piperazine (piperazine is about 1.8 mol / L, piperazine-N, N′-biscarbodithioate potassium salt Therefore, piperazine can be further dissolved in a saturated solution of piperazine-N, N′-biscarbodithioic acid potassium salt. In addition, since the saturated aqueous solution of piperazine-N, N′-biscarbodithioate produced has low liquid viscosity, it is excellent in reactivity (handleability).

  A carbodithioate of an amine other than piperazine-N, N′-biscarbodithioate, for example, a supersaturated solution of a carbodithioate such as tetraethylenepentamine, diethylenetriamine, and polyethyleneimine, does not precipitate a solid and becomes viscous. Therefore, it is difficult to obtain a stable solid amine carbodithioate.

  In the method of the present invention, it is preferable to dissolve piperazine in a saturated aqueous solution of piperazine-N, N′-biscarbodithioic acid potassium salt, add carbon disulfide first, and then add potassium hydroxide. In a saturated aqueous solution of piperazine-N, N′-biscarbodithioic acid potassium salt, a gel-like by-product is formed when piperazine and carbon disulfide are reacted in an excess of potassium hydroxide, and a continuous reaction occurs. It can be difficult.

  In the method of the present invention, piperazine is continuously produced by dissolving piperazine in a saturated aqueous solution of piperazine-N, N′-biscarbodithioic acid salt and alternately repeating the addition of carbon disulfide and the addition of potassium hydroxide. -N, N'-biscarbodithioic acid potassium can be produced.

  Particularly preferred embodiments include piperazine-N, N′-biscarbohydrate previously reacted in the reaction of piperazine, carbon disulfide and potassium hydroxide in a saturated aqueous solution of piperazine-N, N′-biscarbodithioate. An example is a method in which a carbon disulfide is reacted in an excess state with respect to potassium hydroxide after being dissolved in a saturated aqueous solution of potassium dithioate. When carbon disulfide reacts in an excess state than potassium hydroxide, solid piperazine-N, N′-biscarbodithioic acid is once precipitated, but compared with the case where potassium hydroxide is added first. , Low viscosity, good reactivity and handling, and finally pure piperazine-N, N′-biscarbodithioate crystals are obtained. In particular, a method of adding carbon disulfide and potassium hydroxide at the same time by dividing each time into two or more times or adding a time difference is preferable.

  In the reaction of piperazine, carbon disulfide and potassium hydroxide in an aqueous solution, piperazine-N-carbodithioic acid potassium and thiocarbonate may be by-produced in addition to piperazine-N, N′-biscarbodithioic acid potassium. In addition, unreacted piperazine may remain. Piperazine-N-carbodithioate potassium, which has only one functional group and has a low heavy metal treatment capacity, has higher solubility than piperazine-N, N′-biscarbodithioate potassium, and therefore the method of the present invention has a heavy metal treatment capacity. Only high potassium piperazine-N, N′-biscarbodithioate can be selectively recovered as crystals.

  Similarly, since piperazine and thiocarbonate are highly water-soluble, they remain in the aqueous solution and can be separated from piperazine-N, N′-biscarbodithioate potassium. In the method by concentration or organic solvent extraction, there is a problem that piperazine-N-carbodithioate potassium, piperazine and thiocarbonate precipitate simultaneously with potassium piperazine-N, N′-biscarbodithioate. Then, it is possible to selectively obtain potassium piperazine-N, N′-biscarbodithioate having high heavy metal treatment ability as crystals.

  In the present invention, the method for drying the precipitated crystals is not particularly limited as long as it is a method for obtaining a dihydrate, but it is preferable that the crystal is not excessively dehydrated to an anhydrous product. Even if the crystallinity decreases due to drying of the precipitated crystals, it can be recrystallized by hydration in an atmosphere containing water, and piperazine-N, N′-biscarbodithioate potassium · 2 water. Japanese crystals can be obtained. Crystallization by hydration after drying is preferably performed in pulverization and / or forced flow.

  The heavy metal treating agent comprising piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention is mixed with heavy metal-containing soil, waste water, waste, incinerated ash, etc. Elution can be prevented. The method of using the heavy metal treatment agent of the present invention in the heavy metal immobilization treatment can be applied in the same manner as other normal heavy metal treatment agents, such as water, alkali hydroxide or iron chloride as required for the heavy metal treatment agent. You may mix and use suitably with a pH adjuster.

  Piperazine-N, N′-biscarbodithioate potassium dihydrate may be used after being dissolved in water and mixed with a heavy metal-containing material, but it is preferable to mix directly with water, particularly direct mixing. It is preferable to add water after use.

  Since the heavy metal treating agent of piperazine-N, N′-biscarbodithioate potassium dihydrate of the present invention has a high content of components having heavy metal treating ability, there is no problem of weight change or consolidation during storage. It is excellent in transportability and storage stability, can be treated with heavy metals by direct mixing with heavy metal containing materials, does not generate harmful gases during storage and use, and has high reaction selectivity to harmful lead.

The X-ray diffraction pattern of the anhydrous piperazine-N, N'-biscarbodithioate dihydrate and dihydrate is shown. In the figure, the horizontal axis (X axis) represents 2θ values (unit: deg) in X-ray diffraction, the vertical axis (Y axis) represents peak intensity in X-ray diffraction, and the scale is arbitrary. Dihydrate has high crystallinity. Piperazine-N, N'-biscarbodithioate anhydrate, dihydrate, lead chloride and pure water (lead chloride and piperazine-N, N'-biscarbodithioate hydrate total solid It is the figure which evaluated the production | generation of the lead complex at the time of mixing 20 weight% with respect to a part by X-ray diffraction. Piperazine-N, N'-biscarbodithioate anhydrate, dihydrate and copper chloride and pure water (total solid of copper chloride and piperazine-N, N'-biscarbodithioate hydrate It is the figure which evaluated the production | generation of the copper complex at the time of mixing 20 weight% with respect to a minute by X-ray diffraction.

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

Example 1
Piperazine 68.45 g, pure water 123.58 g, carbon disulfide 121.01 g, 48% potassium hydroxide 186.96 g, and piperazine was dissolved in pure water at 40 ° C., and then disulfide with stirring in a nitrogen stream. Carbon and 48% potassium hydroxide were added dropwise, alternately divided into 4 parts. After completion of the dropwise addition, a slurry solution in which piperazine-N, N′-biscarbodithioic acid potassium dihydrate was precipitated was obtained.

  Precipitated potassium piperazine-N, N′-biscarbodithioate was filtered off, and the adhering moisture was removed with a vacuum dryer, followed by drying.

  The obtained potassium piperazine-N, N′-biscarbodithioate was found to be dihydrate as a result of thermal analysis, and its X-ray diffraction pattern had high crystallinity as shown in FIG.

The obtained piperazine-N, N′-biscarbodithioate dihydrate was dissolved in pure water and subjected to ¹³ C-NMR measurement. As a result, piperazine and piperazine-N-biscarbodithioate potassium were detected. Was not.

Example 2
In addition, 300.42 g of piperazine-N, N′-biscarbodithioate in Example 1 (saturated aqueous solution of piperazine-N, N′-biscarbodithioate) and 30.42 g of piperazine and 31. 00 g was added, dissolved at 40 ° C., and 53.78 g of carbon disulfide and 84.80 g of 48% potassium hydroxide were alternately added in two portions while stirring in a nitrogen stream. After completion of the dropping, a slurry solution in which potassium piperazine-N, N′-biscarbodithioate was precipitated was obtained.

  It was confirmed that piperazine-N, N′-biscarbodithioic acid potassium salt was obtained by repeatedly using the saturated solution.

Comparative Example 1
The dihydrate of Example 1 was further dried at 100 ° C. in a dryer to obtain an anhydrous product. As shown in FIG. 1, the anhydrate was different from the dihydrate in crystallinity and had low crystallinity.

Comparative Example 2
The same operation as in Example 1 was conducted except that piperazine was changed to tetraethylenepentamine, and 88.11 g of tetraethylenepentamine, 128.11 g of pure water, 127.50 g of carbon disulfide, and 156.28 g of 48% sodium hydroxide were used. However, a solid carbodithioate was not obtained.

(Storage stability evaluation 1 Change in weight)
Piperazine-N, N′-biscarbodithioate potassium dihydrate and anhydrate obtained in Example 1 and Comparative Example 1 were allowed to stand in the air, and the change with time in weight change was measured. The results are shown in Table 2.

無水和物は重量変化したが、２水和物では重量変化がなく、大気中の保存で安定であることが確認された。

The non-hydrate changed in weight, but the dihydrate did not change in weight, and it was confirmed that it was stable when stored in the atmosphere.

  After standing in the air, the dihydrate was not consolidated, but the anhydride was found to have decreased fluidity and adhered to the container.

(Heavy metal immobilization test)
For 50 parts by weight of fly ash A (Pb = 2500 ppm), 0.5 parts of piperazine-N, N′-biscarbodithioate potassium dihydrate of Example 1 (in terms of anhydrate) is 25 parts by weight of water. Then, 0.5 parts by weight of dihydrate (anhydrous equivalent) was directly added to the ash, and then 25 weights of water was added to the ash and kneaded. Thereafter, a dissolution test was conducted according to the Environmental Agency Notification No. 13 test.

  The elution of lead was less than 0.05 ppm and met the environmental standards.

(Gas measurement 1)
In a Tedlar bag (volume 1 L), piperazine-N, N′-biscarbodithioate potassium dihydrate 2.2 g (corresponding to 2.0 g in terms of piperazine-N, N′-biscarbodithioate potassium), air Of 500 ml, and left at room temperature and 65 ° C. for 1 hour. After standing, the carbon disulfide concentration in the head space of the Tedlar bag was measured with a detector tube.

  For comparison, anhydrous piperazine-N, N′-biscarbodithioate potassium anhydrate (each equivalent to dihydrate in terms of potassium piperazine-N, N′-biscarbodithioate) and disulfide The carbon concentration was measured. The results are shown in Table 3.

  Generation of carbon disulfide was observed in the anhydride, but not in the dihydrate.

（ガス測定２）
テドラーバッグ（容積１Ｌ）中に、飛灰Ｂ（Ｐｂ＝２７００ｐｐｍ）３０ｇに対して純水３５重量％及びピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウム・２水和物を０．７重量％添加し、混合した後空気を５００ｍＬ装填し、６５℃で１時間加熱した。加熱後、テドラーバッグのヘッドスペースの硫化水素及び二硫化炭素濃度を検知管で測定した。

(Gas measurement 2)
In Tedlar bag (volume 1L), 35% by weight of pure water and 0.7% by weight of piperazine-N, N'-biscarbodithioate potassium dihydrate are added to 30g of fly ash B (Pb = 2700ppm). After mixing, 500 mL of air was charged and heated at 65 ° C. for 1 hour. After heating, the hydrogen sulfide and carbon disulfide concentrations in the head space of the Tedlar bag were measured with a detector tube.

  The same gas measurement was performed by adding 20% by weight of pure water and 1.1% by weight of piperazine-N, N′-biscarbodithioate potassium dihydrate to Fly Ash C (Pb = 9800 ppm).

  The results are shown in Table 5. There was no generation of hydrogen sulfide or carbon disulfide.

（鉛に対する反応選択性）
ピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウムの２水和物及び無水和物をピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウム成分換算で１０ｇをそれぞれ塩化鉛８．８ｇ及び塩化銅４．３ｇと純水（塩化鉛又は塩化銅及びピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウムの水和物の総固形分に対して２０重量％及び３０重量％）とで混合し、混合後の各金属錯体の生成をＸ線回折で測定した。

(Reactivity selectivity for lead)
Piperazine-N, N′-biscarbodithioate dihydrate and anhydrate thereof are converted into potassium piperazine-N, N′-biscarbodithioate components as 10 g, lead chloride 8.8 g and copper chloride 4. 3 g and pure water (20 wt% and 30 wt% based on the total solid content of lead chloride or copper chloride and piperazine-N, N′-biscarbodithioate hydrate) The formation of each metal complex was measured by X-ray diffraction.

  Lead complex, copper complex and piperazine-N, N′-biscarbodithioate potassium diffraction angle 9.4 ° (lead complex-derived peak (a)), 15.1 ° (copper complex-derived peak (b)) And 33.1 ° (peak (c) derived from piperazine-N, N′-biscarbodithioate potassium component), a / c is lead-reactive and b / c is copper-reactive. These ratios were taken as lead selectivity. Tables 5 and 6 show the results when the water content is 20% by weight and 30% by weight.

  The dihydrate has a higher reaction selectivity to lead than the anhydride, and the tendency is more marked when the water content in the heavy metal-containing material is smaller.

  The heavy metal treating agent of the present invention can be used for immobilizing heavy metals in a heavy metal-containing material, and particularly suitable for treating heavy metals in fly ash containing a large amount of lead.

Claims (10)

A heavy metal treating agent comprising piperazine-N, N′-biscarbodithioate potassium dihydrate. The heavy metal treating agent according to claim 1, comprising piperazine-N, N'-biscarbodithioate potassium dihydrate having crystallinity of the X-ray diffraction pattern of Table 1.

The heavy metal treating agent according to claim 1 or 2, comprising piperazine-N, N'-biscarbodithioate potassium in an amount of 85% or more. The heavy metal treating agent according to any one of claims 1 to 3, further comprising an alkali hydroxide and / or an alkaline earth hydroxide. Piperazine, carbon disulfide, and potassium hydroxide are reacted in a saturated aqueous solution of piperazine-N, N′-biscarbodithioic acid potassium salt to precipitate piperazine-N, N′-biscarbodithioic acid potassium salt, and the salt The method for producing a heavy metal treating agent according to any one of claims 1 to 4, wherein the process is separated. 6. The carbon disulfide is added first in a saturated aqueous solution of piperazine-N, N′-biscarbodithioic acid potassium salt in which piperazine is dissolved, and potassium hydroxide is added later. Manufacturing method. The method according to claim 5 or 6, wherein the addition of carbon disulfide and the addition of potassium hydroxide are alternately repeated in a saturated aqueous solution of piperazine-N, N'-biscarbodithioic acid potassium salt in which piperazine is dissolved. The heavy metal processing agent which mixes the heavy metal processing agent in any one of Claims 1 thru | or 4 with a heavy metal containing material directly. The heavy metal treatment method according to claim 8, wherein the amount of water added to the total solid content of the heavy metal-containing material and the heavy metal treatment agent according to any one of claims 1 to 4 is 10 wt% or more and 50 wt% or less. The heavy metal processing agent in any one of Claims 1 thru | or 4 is melt | dissolved in water, The processing method of the heavy metal which mixes the said aqueous solution and a heavy metal containing material.

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