JP2829707B2 - Dithiocarbamate aqueous solution having low-temperature stability and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vulcanizing agent for rubber, incinerated ash generated from a garbage incineration plant, and fly ash collected from an electric dust collector, etc. The present invention relates to an improvement in the low-temperature stability of an aqueous solution of dithiocarbamate used as a heavy metal treating agent for insolubilizing and separating and removing harmful heavy metals contained in water.

[0002]

2. Description of the Related Art Various methods have been employed for separating and removing heavy metals contained in incineration ash, fly ash, smoke washing wastewater and the like generated in a refuse incineration plant. For example, heavy metals contained in smoke washing wastewater and the like are converted to hardly soluble compounds in the presence of a chelating agent such as sulfide and dithiocarbamate by setting an appropriate pH in an aqueous solution, and the coagulation sedimentation and It is separated and removed by a method such as flocculation. Also,
In the treatment of incinerated ash, fly ash or heavy metals contained in smoke washing wastewater, the method of separating and removing with chemicals such as chelating agents can be easily implemented without newly installing special equipment, and the effect is high. Widely adopted. Among them,
Sulfides, dithiocarbamates and the like are widely used as chelating agents for the treatment of these heavy metals.

[0003] As described above, dithiocarbamates are widely used as chelating agents for treating heavy metals, and also widely used as vulcanizing agents for rubbers such as natural rubber and isoprene rubber. Dithiocarbamate, which is used for vulcanizing agents for rubber and for removing heavy metals in incineration ash, fly ash, smoke washing wastewater, etc., or preventing re-elution, is usually used as a concentrated aqueous solution. Have been.

[0004]

However, when the dithiocarbamate aqueous solution is used at a low temperature such as in a cold region, for example, at -10 ° C., the dithiocarbamate component is crystallized, and the dithiocarbamate solution is crystallized. Work at low temperatures such as
Restrictions have been placed on storage and storage, and not only the cost has been increased, but also there have been various problems such as the need for cumbersome operations, and it has been extremely difficult to handle. The present invention solves the above-described problems, and provides a low-temperature stability that can be used in a stable state even at a low temperature such as in a cold region without impairing the advantage of dithiocarbamate having a strong chelating action. It is an object of the present invention to provide a dithiocarbamate aqueous solution and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION The present invention is characterized in that a concentrated aqueous solution of dithiocarbamate contains at least one of xanthate, thiourea, and a dithiocarbamate different from the dithiocarbamate. With respect to 100 parts by weight of a dithiocarbamate aqueous solution having a low-temperature stability and a concentrated aqueous solution of dithiocarbamate, at least one of xanthate, thiourea, and a dithiocarbamate different from the dithiocarbamate is used in an amount of 0.5 to 5 parts by weight. This is a method for producing an aqueous solution of dithiocarbamate having low-temperature stability, characterized by adding parts by weight.

The dithiocarbamate used in the present invention has a chemical structure represented by the general formula (1), wherein R and R 'are hydrogen, methyl, ethyl,
An alkyl group such as n-propyl, isopropyl, n-butyl, isobutyl and pentyl; and an aromatic group such as phenyl and benzyl, and R and R 'may or may not be the same. M represents potassium, sodium, and lithium. In addition, R and R ′ in the general formula (1) are linked to form an alkylene group such as methylene, ethylene, and propylene.
It may be cyclic, or may be a polymeric dithiocarbamate such as a polyalkyleneimine dithiocarbamine residual salt.

[0007]

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Examples of the dithiocarbamate include sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, sodium ethylenebisdithiocarbamate, sodium methyldithiocarbamate, sodium ethyldithiocarbamate, sodium n-butyldithiocarbamate, and n-butyldithiocarbamate. Sodium propyldithiocarbamate, sodium methylethyldithiocarbamate,
Examples thereof include sodium methyl n-butyldithiocarbamate, sodium ethyl n-butyldithiocarbamate, sodium phenyldithiocarbamate, and sodium benzyldithiocarbamate.

The xanthate used in the present invention has a chemical structure represented by the general formula (2), wherein R is methyl, ethyl, n-propyl, isopropyl,
It represents an alkyl group such as n-butyl and isobutyl, or an aromatic group such as phenyl and benzyl.

[0010]

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Examples of the xanthate include o-ethyl potassium dithiocarbonate, o-methyl sodium dithiocarbonate, on-propyl potassium dithiocarbonate, o-isobutyl sodium dithiocarbonate, o-phenyl sodium dithiocarbonate, o-benzyl dithiocarbonate And sodium.

The thiourea used in the present invention has a chemical structure represented by the general formula (3), wherein R _1, R _2, R _{3 and} R ₄ are each hydrogen, methyl, It represents an alkyl group such as ethyl, propyl and butyl, and an alkylene group such as ethylene and propylene.

[0013]

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As thiourea, for example, in addition to thiourea, ethylene thiourea, 1,2-propylene thiourea,
2,3-butylenethiourea, N-methylthiourea, N-ethylthiourea, N-propylthiourea, N-butylthiourea, N, N'-dimethylthiourea, N, N'-diethylthiourea, N, N'dipropylthiourea, N-methyl, N'-ethylthiourea , N-methyl, N-propylthiourea, N, N-dimethylthiourea, N, N-diethylthiourea, N, N-dipropylthiourea and the like.

The concentrated aqueous solution in the present invention is a solution in which dithiocarbamate is dissolved in water at a concentration in a range between a saturated concentration at which the dithiocarbamate is dissolved in water at room temperature (about 25 ° C.) and 10% or less of the saturated concentration. The specific concentration is at least 30% by weight. This solution may contain an alkali such as sodium hydroxide or potassium hydroxide, an acid such as hydrochloric acid or sulfuric acid, or an antioxidant or a water-soluble organic solvent such as methanol or ethanol for adjusting the hydrogen ion concentration. Good.

The amount of xanthate, thiourea and dithiocarbamate different from the above dithiocarbamate to be added to the concentrated aqueous solution of dithiocarbamate is 0.5 to 5 parts by weight per 100 parts by weight of the concentrated aqueous solution of dithiocarbamate. Parts by weight, preferably 0.4 to 4 parts by weight. When the amount is less than 0.5 part by weight, crystallization of the component occurs, and when the amount exceeds 5 parts by weight, the effect as a rubber vulcanizing agent or a heavy metal treating agent decreases, which is not preferable.

[0017]

According to the present invention, a concentrated aqueous solution of dithiocarbamate used for the treatment of separating and removing heavy metals contained in rubber vulcanizing agents, heavy metal-containing wastewater, incineration ash, fly ash, etc., has a thioketone group. And a xanthate which is a compound having a non-carbon atom bonded to the carbon of the thioketone group,
By adding thiourea, a dithiocarbamate different from the dithiocarbamate, without impairing the original advantages of the dithiocarbamate, for example, at -10 ° C.
A concentrated aqueous solution of dithiocarbamate that is easy to crystallize at low temperatures such as xanthate, thiourea, and dithiocarbamate that is different from the dithiocarbamate will be stably retained without crystallization in the presence of Handling, storage, and storage in cold regions are facilitated without careful management.

[0018]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples. The percentages in the examples represent% by weight.

Example 1 To 100 parts by weight of a 42% aqueous solution of sodium dimethyldithiocarbamate was added o-ethyl potassium dithiocarbonate, thiourea, ethylenethiourea, 1,3-dimethylthiourea, sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, ethylenebis Each of sodium dithiocarbamate and sodium methyldithiocarbamate is 0.5, 1.0, 2.0, 3.0
, 5.0 parts by weight and dissolved.

The obtained aqueous solution was placed in a sealed plastic bottle having a capacity of 10 ml, immersed in a low-temperature constant temperature water bath set at -10 ° C. for 3 days, and it was tested whether or not the solution crystallized. As shown in Table 1, when 0.5 to 5.0 parts by weight of the stabilizer was used, no crystallization was observed at -10 ° C for 3 days.

[0021]

[Table 1]

Example 2 37 parts by weight of sodium diethyldithiocarbamate was added to 6 parts by weight of
It was added to and dissolved in 3 parts by weight of an aqueous solution of sodium hydroxide. 0.5, 1.0, 2.0, 3.0 and 5.0 parts by weight of 1,3-dimethylthiourea, sodium dibutyldithiocarbamate, sodium ethylenebisdithiocarbamate and sodium methyldithiocarbamate were added to 100 parts by weight of the aqueous sodium dithiocarbamate solution, respectively. Added and dissolved.

The obtained aqueous solution was placed in a sealed plastic bottle having a capacity of 10 ml, immersed in a low-temperature constant temperature water bath set at -10 ° C. for 3 days, and it was tested whether or not the solution crystallized. As shown in Table 2, when 0.5 to 5.0 parts by weight of the stabilizer was used, no crystallization was observed at -10 ° C for 3 days.

[0024]

[Table 2]

Example 3 40 parts by weight of sodium diethyldithiocarbamate were prepared by adding 0.5 parts by weight of sodium dibutyldithiocarbamate and 0.5 to 5.0 parts by weight of sodium ethylenebisdithiocarbamate.
It was dissolved in 60 parts by weight of an aqueous solution to which 0 part by weight was added. The obtained aqueous solution was placed in a sealed plastic bottle having a capacity of 10 ml, and immersed in a low-temperature constant-temperature water bath set at -10 ° C for 3 days.
The solution was tested for crystallization. As shown in Table 3, no component crystallization was observed at -10 ° C for 3 days.

[0026]

[Table 3]

Comparative Example 1 Ethylene glycol, glycerin, ethanol, 2,5-dithiobiurea, and dodecylbenzenesulfonate were added to 100 parts by weight of a 42% aqueous solution of sodium dimethyldithiocarbamate at 1.0, 2.0, 3.0. 4.0
, 5.0 parts by weight and dissolved. The obtained aqueous solution is put into a sealed plastic bottle having a capacity of 10 ml, and
It was immersed for 3 days in a low-temperature constant temperature water bath set at 0 ° C., and it was tested whether or not the solution crystallized. The results are shown in Table 4,
In each case, component crystallization was observed at -10 ° C for 3 days.

[0028]

[Table 4]

[0029]

As is clear from the above description, according to the present invention, the concentrated dithiocarbamate used for the treatment such as the separation and removal of rubber vulcanizing agents, wastewater containing heavy metals, incineration ash, fly ash, etc. Aqueous solution can be stabilized at low temperature,
Without special management, it can be handled in cold regions, and the above processing can be performed cheaply and easily in cold regions, and excellent effects such as easy storage and storage can be achieved. Becomes

Claims (2)

(57) [Claims] 1. A dithiocarbamine having low-temperature stability, characterized in that a concentrated aqueous solution of dithiocarbamate contains at least one of xanthate, thiourea, and a dithiocarbamate different from the dithiocarbamate. Aqueous acid salt solution. 2. A concentrated aqueous solution of dithiocarbamate 10
A low-temperature-stable dithiocarbamate characterized by adding 0.5 to 5 parts by weight of xanthate, thiourea, and a dithiocarbamate different from the dithiocarbamate to 0 parts by weight. A method for producing an aqueous solution.