JPH057078B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a metal collection method. [Prior art] In recent years, as the pollution of rivers, oceans, etc. by wastewater from factories has become a problem, regulations to prevent pollution by wastewater have been strengthened, and metals contained in wastewater must be kept below a specified concentration. It is mandatory that
Particularly strict regulations are in place for heavy metals that are harmful to the human body, such as mercury, cadmium, zinc, lead, copper, and chromium. For this reason, various methods have been proposed to remove metals from wastewater, including ion flotation, ion exchange, electrolytic flotation, electrodialysis, reverse osmosis, slaked lime, A known method is a neutralization coagulation-sedimentation method, in which metals are turned into hydroxides by adding an alkaline neutralizing agent such as caustic soda, and then removed by coagulation and precipitation using a polymer flocculant. A method of collecting and removing metals using a metal scavenger is also known, and a metal scavenger containing aliphatic polydithiocarbamic acid or its salts is known as this type of metal scavenger. (Japanese Patent Publication No. 49-99978). [Problems to be solved by the invention] However, ion flotation, ion exchange,
The electrolytic flotation method, electrodialysis method, and reverse osmosis method have problems with the removal rate of heavy metals, operability, running costs, etc., and are currently only used for some special wastewater treatments. In addition, the neutralization coagulation precipitation method generates a large amount of metal hydroxide sludge, and these hydroxide sludges have problems such as poor dewatering properties and large sludge volumes, making it difficult to transport. It is also very difficult to remove it below the standard value. Moreover, depending on how these sludge is disposed of, there is also the problem that it may re-melt and cause secondary pollution. On the other hand, although the above problems can be solved by a method of collecting and removing metals using a metal scavenger containing aliphatic polydithiocarbamic acid or its salts, the molecular weight of this metal scavenger is small. Therefore, it is necessary to add a large amount, and the floc produced is small, resulting in problems such as poor sedimentation properties. [Means for solving the problem] As a result of intensive research in view of the above points, the present inventors found that at least one carbodithioic acid substituted with the active hydrogen atom of a polycondensed polyamine obtained by polycondensing polyamines and epihalohydrin. We discovered that polyamine derivatives having groups and/or salts thereof as substituents had excellent performance as metal scavengers, and filed an application (Japanese Patent Application No. 89998-1989).
As a result of further intensive research, it was discovered that metal ions in wastewater can be collected most efficiently by using the above polyamine derivative in combination with at least one of sodium monosulfide, sodium polysulfide, and sodium hydrogen sulfide, and the present invention has been achieved. It was completed. The metal collection method of the present invention includes a polyamine derivative having as a substituent at least one carbodithioic acid group and/or a salt thereof substituted with an active hydrogen atom of a polycondensed polyamine obtained by polycondensation of a polyamine and an epihalohydrin; This is a method of collecting and removing metal ions in wastewater by adding at least one of sodium sulfide, sodium polysulfide, and sodium hydrogen sulfide to wastewater containing metal ions. The polyamine derivative used in the present invention has at least one carbodithioic acid group substituted with the active hydrogen atom of the polycondensed polyamine: -CSSH and/or
or its salts as a substituent, which is obtained by polycondensing polyamines and epihalohydrin to obtain a polycondensed polyamine, and then introducing a carbodithioic acid group and/or its salts as a substituent into the polycondensed polyamine. It can be obtained by a method in which a carbodithioic acid group and/or a salt thereof is introduced as a substituent into polyamines, and then polycondensed with epihalohydrin. Further, in the polyamine derivative used in the present invention, one or more types of an alkyl group, a hydroxyalkyl group, and an acyl group may be bonded to the nitrogen atom of the polycondensed polyamine as an N-substituent.
The above N-substituents are used to convert polyamines into methyl halide, ethyl halide, butyl halide, lauryl halide, etc. before polycondensation with epihalohydrin.
Alkyl halides such as stearyl halide; epoxy alkanes such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, 1,2-dodecyl epoxy alkane, 1,2-octacosyl epoxy alkane, or acetic acid, propionic acid, butyric acid, caproic acid , by reacting with fatty acids such as caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, esters of these fatty acids, or acid halides of these fatty acids, or by polycondensing polyamines and epihalohydrin. It can be introduced by forming a polycondensed polyamine and then reacting it with an alkyl halide, an epoxy alkane, or a fatty acid as described above. Further, as the N-substituent, two or more of the same type may be present in the molecule, or two or more of different types may be present in the molecule. The polyamine derivatives used in the present invention may have a structure in which a carbodithioic acid group and/or its salts are bonded to the nitrogen atom of a polycondensed polyamine, or may have a structure in which a carbodithioic acid group and/or its salts are bonded to the nitrogen atom of a polycondensed polyamine. It may have a structure in which a carbodithioic acid group and/or its salt is bonded to an oxygen atom in substitution for a hydrogen atom, or it may have a structure in which it is bonded to both a nitrogen atom and an oxygen atom. Examples of the salts of the carbodithioic acid group include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts and magnesium salts, and ammonium salts. The above polyamines have 1 or 2 atoms per nitrogen atom.
A compound having two or more imino or amino groups formed by bonding active hydrogen atoms, such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine. , polyalkylene polyamines such as tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine, pentaethylenehexamine; phenylenediamine, xylenediamine,
meta-xylene diamine, iminobispropylamine, monomethylaminopropylamine, methyliminobispropylamine, 1,3-bis(aminomethyl)cyclohexane, 1,3-diaminopropane, 1,4-diaminobutane, 3,5-diamino Examples include chlorobenzene, melamine, 1-aminoethylpiperazine, piperazine, diaminophenyl ether, 3,3'-dichlorobenzidine, tolidine base, m-tolylenediamine, and polyethylene polyimine (average molecular weight 300 or more). In addition to the above polyamines, it is also possible to use N-alkyl polyamines, N-hydroxyalkyl polyamines, N-acyl polyamines, etc. obtained by reacting these polyamines with alkyl halides, epoxy alkanes, or fatty acids. . As the N-alkyl polyamine, N-alkylethylenediamine, N-
Alkylpropylene diamine, N-alkylhexamethylene diamine, N-alkylphenylene diamine, N-alkylxylene diamine, N-alkyldiethylenetriamine, N-alkyltriethylenetetramine, N-alkyltetraethylenepentamine, N-alkylpentaethylenehexamine etc. can be used. The N-substituted alkyl group preferably has 2 to 18 carbon atoms. Examples of N-hydroxyalkylpolyamines include N-hydroxyethylpolyamine, N-hydroxypropylpolyamine, N-hydroxybutylpolyamine, and N-hydroxybutylpolyamine.
-β-hydroxydodecylpolyamine, N-β-
Examples include hydroxytetradecylpolyamine, N-β-hydroxyhexadecylpolyamine, N-β-hydroxyoctadecylpolyamine, N-β-hydroxyoctacosylpolyamine, and the like. In addition, N-acylpolyamines include N-acetylpolyamine, N-propionylpolyamine, N-
Butyryl polyamine, N-caproyl polyamine, N-lauroyl polyamine, N-oleoyl polyamine, N-myristyroyl polyamine, N
-stearoylpolyamine, N-beheroylpolyamine, and the like. These polyamines can be used alone or in combination of two or more.
Epihalohydrins include epichlorohydrin, epipromhydrin, epiiodohydrin,
etc. The polyamine derivatives used in the present invention are polyamines that are polycondensed with epihalohydrin (if a substituent is introduced into the polyamine before polycondensation with epihalohydrin, the polyamine before the introduction of the substituent) is a diamine having two amino groups. In some cases, it has a linear structure and is generally water-soluble. Further, when it has a crosslinked structure, it has dispersibility or suspendability in water. In the method of the present invention, the above polyamine derivative and at least one of sodium monosulfide, sodium polysulfide, and sodium hydrogen sulfide are added to wastewater to collect and remove metal ions in the wastewater. As the sodium polysulfide, sodium disulfide, sodium trisulfide, sodium tetrasulfide, and sodium pentasulfide are used. The purpose of the present invention can be achieved if the weight ratio of the polyamine derivative and the above-mentioned sodium sulfides is 1:99 to 99:1, but especially 20:80 to 98:1.
It is preferable that it is 2. The polyamine derivative and sodium sulfide may be mixed in advance and added to the wastewater, or may be added to the wastewater separately, but it is preferable to mix them in advance and add them to the wastewater. Incidentally, when adding them separately, the effect of removing metal ions is almost the same whether the polyamine derivative is added first and then the sodium sulfides are added, or the metal ion removal effect is added in the reverse order. The polyamine derivative used in the present invention can be used alone as a metal scavenger, but when used in combination with sodium sulfide, the generated flocs are larger, the time required for floc sedimentation can be shortened, and metal ions in wastewater can be removed. Can be efficiently collected and removed. Sodium sulfides also have the ability to form complexes with metal ions, but when used alone, the flocs produced are extremely small, making it difficult to precipitate and remove the flocs. Metal ions in wastewater can be efficiently collected and removed. This is due to the ability of polyamine derivatives to form complexes with metal ions,
It is thought that the complex-forming ability of sodium sulfides and metal ions act in a mutually effective manner. Therefore, the amount of the polyamine derivative and sodium sulfide added to the wastewater is preferably such that the total amount of both is 0.7 to 4 molar equivalents, particularly 0.9 to 1.5 molar equivalents, of the amount of metal ions in the wastewater. In the present invention, when collecting and removing metal ions in wastewater by adding polyamine derivatives and sodium sulfides to wastewater, it is preferable to adjust the pH of the wastewater to 3-10, particularly 4-9. The acid or alkali used to adjust the pH may be anything as long as it does not inhibit the formation of flocs, but the acid used is usually hydrochloric acid, sulfuric acid, nitric acid, etc., and the alkali used is sodium hydroxide, potassium hydroxide, etc. , calcium hydroxide, etc. are used. According to the method of the present invention, mercury, cadmium, zinc,
Metals such as lead, copper, chromium, arsenic, gold, silver, platinum, vanadium, and thallium can be efficiently collected and removed. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 261.1 g of metaxylene diamine and a water-acetone (1:1) mixture were placed in a four-necked flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser.
300g was added and heated to 60°C with stirring, and 174g of epichlorohydrin was added dropwise over 4 hours while controlling the temperature so as not to exceed 90°C. After the dropwise addition was completed, the temperature was maintained at 80 to 90°C for 1 hour. 727 g of a water-acetone solution of a polycondensed polyamine obtained by polycondensing meta-xylene diamine and epichlorohydrin was obtained. Next, 234.1 g of the polycondensed polyamine solution, 517.4 g of pure water, and 59.9 g of sodium hydroxide were placed in the same apparatus as above, and 86.9 g of carbon disulfide was added dropwise over 3 hours while stirring at 40°C. After further holding at the same temperature for 1 hour, water-acetone was distilled off at 60 to 90°C to obtain a polyamine derivative. The sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of the above polyamine derivative, and a Cu ²⁺ -containing aqueous solution, a Cd ²⁺ -containing aqueous solution, a Hg ²⁺ -containing aqueous solution, a Pb ²⁺ -containing aqueous solution ( Each of the four types of aqueous solutions with a metal ion content of 50 ppm and PH = 5.0)
A 0.5 wt % aqueous solution of the above mixture was added to 1000 ml in the amount shown in Table 1, stirred for 5 minutes, and left to stand, and the time until the formed flocs precipitated was measured. The results are shown in Table 1. After the generated flocs were filtered out, the concentration of metal ions remaining in the liquid was measured by atomic absorption spectrometry. The results and the amount of flocs separately collected are also shown in Table 1. Example 2 Ethylenediamine was placed in an apparatus similar to Example 1.
30.6 g, pure water 450 g, and potassium hydroxide 57.2 g were added, and 77.5 g of carbon disulfide was added dropwise at 50°C over 4 hours, and then heated at 60°C for 3 hours to form a solution containing potassium carbodithioate base as a substituent. An ethylenediamine derivative was obtained. Next, the mixture was cooled to 30°C, 47.2g of epichlorohydrin was added dropwise over 5 hours, and the reaction was continued at 70 to 90°C for 3 hours. 308g of pure water was added to form a mixture containing 20.0wt% polyamine derivative. An aqueous solution was obtained. The sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and a 2 wt% aqueous solution of the above mixture was added to 1000 ml of each of the four metal ion-containing aqueous solutions similar to Example 1. The amounts shown in Table 1 were added, and the flocculation time, flocculation amount, and residual metal ion concentration in the solution were measured in the same manner as in Example 1. The results are also shown in Table 1. Example 3 In a 500 ml four-neck flask equipped with a thermometer, reflux condenser, stirrer, and dropping funnel, 71.2 g of metaxylene diamine and 279 g of a 7.5% aqueous sodium hydroxide solution were added.
79.6 g of carbon disulfide was added dropwise over 6 hours at 45°C with vigorous stirring. After the dropwise addition, the reaction was carried out at the same temperature for 1.5 hours, and then at 70°C for 2 hours. An aqueous solution of a reaction product having an acid group and a sodium carbodithioate base as a substituent was obtained. Put 400g of the above aqueous solution and 267.3g of pure water into the same device as above, and heat 50.3g of epichlorohydrin at 60℃.
was added over 4 hours, and the reaction was further carried out at 70 to 80°C for 1 hour to obtain a 28.1 wt % aqueous solution of a polyamine derivative. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 4 Diethylenetriamine was added to the same apparatus as in Example 3.
21.0g, pure water 326.4g and sodium hydroxide 24.5g
g, and 46.5 g of carbon disulfide was added dropwise at 40° C. over 3 hours. After the dropwise addition was completed, the reaction was further carried out at 70°C, and then cooled to approximately 30°C and epibromohydrin 34.4
g was added over 2 hours, the temperature was raised to 80 to 90°C, and the reaction was continued for 2 hours to obtain an aqueous solution containing 27.1% of the polyamine derivative. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 5 Diethylenetriamine was added to the same apparatus as in Example 1.
29.9 g and 120 g of toluene were added thereto, and 26.8 g of epichlorohydrin was added dropwise over 3 hours at 40 to 50°C. After the dropwise addition was completed, the reaction was continued at 60°C for 2 hours. Next, add 46.4g of sodium hydroxide and pure water to this.
Add 641.8g of carbon disulfide to 66.1g of carbon disulfide at 40℃.
The mixture was added dropwise over a period of time, and after the completion of the addition, the reaction was further carried out at 70°C for 4 hours. After the reaction was completed, the mixture was cooled to 30° C., stirring was stopped, and the mixture was separated into two layers. After removing the toluene in the upper layer, it was heated to 40°C with stirring, and 48.9 g of epibromohydrin was added dropwise over 3 hours. After the dropwise addition, the reaction was continued at 70 to 80°C for 1 hour, and 22.6 wt% polyamine was added. An aqueous solution containing the derivative was obtained. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 6 Diethylenetriamine was added to the same apparatus as in Example 1.
31.1g was added, and 123.2g of epoxyalkane (alkyl group has 28 carbon atoms) was added dropwise at 90℃ over 30 minutes.
After the dropwise addition, the reaction was further carried out at the same temperature for 2 hours, and N
-Hydroxyalkyldiethylenetriamine was obtained. Next, it was cooled to 40℃, and 667.7g of pure water was added to it.
After adding 24.2 g of sodium hydroxide, 45.9 g of carbon disulfide was added dropwise over 2 hours.
The reaction was continued for 3 hours at ℃. After the reaction is completed, 80-90
27.9g of epichlorohydrin was added dropwise over 3 hours at ℃, and after the dropwise addition was completed, the reaction was continued for another 3 hours at 90-100℃, and then 260.9g of pure water was added to give a concentration of 20.0wt%.
An aqueous solution of polyamine derivative was obtained. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 7 62.7 g of N,N′′′′-bis(hydroxyethyl)triethylenetetramine was placed in the same apparatus as in Example 3, and 24.8 g of epichlorohydrin was added at 50°C.
The mixture was added dropwise over a period of time, and after the completion of the addition, the reaction was continued for an additional 2 hours at 80 to 90°C. Next, 672.7 g of 8% sodium hydroxide aqueous solution was added to this, and 81.5 g of carbon disulfide was added dropwise at 50°C over 2 hours.
The temperature was raised to .degree. C. and the reaction was continued for 3 hours to obtain an aqueous solution containing 22.3% of the polyamine derivative. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 8 22.4 g of polyethyleneimine (average molecular weight 70,000) and 933.2 g of a 1.1% aqueous sodium hydroxide solution were placed in the same apparatus as in Example 1, and 19.7 g of carbon disulfide was added dropwise at 50°C over 1 hour. After completion of the reaction, the reaction was continued for an additional 2 hours at the same temperature. Next, 0.5 g of epichlorohydrin was added dropwise over 3 hours, and then 80 g of
The reaction was continued at ℃ for 2 hours to obtain an aqueous solution containing 5 wt% of the polyamine derivative. Sodium sulfides shown in Table 1 were mixed with 100 parts by weight of this polyamine derivative aqueous solution in the proportions shown in the same table, and pure water was further added to form a 9 wt % aqueous solution. Next, 9 wt% aqueous solution of the above mixture was added in the amount shown in Table 1 to 1000 ml of each of the four metal ion-containing aqueous solutions as in Example 1, and the floc precipitation time, floc production amount, and in-liquid content were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 9 42.5 g of N-methyldiethylenetriamine and 50 g of a water-dioxane (2:1) mixture were placed in the same apparatus as in Example 3, and 33.6 g of epichlorohydrin was added to 70 g of a mixture of water and dioxane (2:1).
Start dropping at a temperature of 95°C, continue dropping for 4 hours while adjusting the temperature so as not to exceed 95°C.
The reaction continued for 2 hours at ~95°C. Next, the mixture was cooled to 40°C, 230g of pure water and 43.6g of sodium hydroxide were added, and 55.3g of carbon disulfide was added dropwise over 3 hours. After the dropwise addition, topping was continued at 70°C under reduced pressure until dioxane was no longer detected. After going, 120g of pure water
was added to obtain a 22.5wt% polyamine derivative aqueous solution. Sodium sulfides shown in Table 1 were mixed in the proportions shown in Table 1 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Example 10 In a device similar to Example 1, 64 g of N-methylethylenediamine, 619.9 g of pure water, and sodium hydroxide were added.
34.6 g of carbon disulfide was added thereto, and 65.7 g of carbon disulfide was added dropwise thereto at 50°C over 3 hours, and after the dropwise addition was completed, the reaction was continued at 70°C for an additional 2 hours. After the reaction was completed, the mixture was cooled to 30°C, 79.9 g of epichlorohydrin was added dropwise at 70°C over 3 hours, and the reaction was further continued at the same temperature for 3 hours to obtain an aqueous solution containing 26.5 wt% of the polyamine derivative. Sodium sulfides shown in Table 2 were mixed in various proportions shown in Table 2 per 100 parts by weight of this polyamine derivative aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 2 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and 24 experiments were conducted with different types of sodium sulfides and amounts added. The procedure was carried out in the same manner as in 1, and the flocculation time, flocculation amount, and residual metal ion concentration in the solution were measured. The results are also shown in Table 2. Comparative Example 1 500 g of a 30% aqueous solution of polyethyleneimine (average molecular weight 20,000) and a 10% aqueous solution were placed in the same apparatus as in Example 1.
1120 g of sodium hydroxide aqueous solution was added, and 212 g of carbon disulfide was added dropwise at 40° C. over 3 hours. After the dropwise addition was completed, the reaction was continued at 45° C. for 3 hours to obtain an aqueous solution containing 23 wt% of the reaction product. The sodium sulfides shown in Table 1 were mixed in the amount shown in Table 1 per 100 parts by weight of this aqueous solution, and pure water was further added to form a 2 wt % aqueous solution. Next, a 2wt% aqueous solution of the above mixture was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to those in Example 1, and the floc precipitation time, floc production amount, and concentration in the solution were determined in the same manner as in Example 1. The residual metal ion concentration was measured. The results are also shown in Table 1. Comparative Example 2 0.5wt% of the same polyamine derivative as Example 1
The aqueous solution was added in the amounts shown in Table 1 to 1000 ml of each of the four types of metal ion-containing aqueous solutions similar to Example 1,
In the same manner as in Example 1, the flocculation time, flocculation amount, and residual metal ion concentration in the solution were measured. The results are also shown in Table 1. Comparative Example 3 30.6 g of ethylenediamine, 450 g of pure water and 57.2 g of potassium hydroxide were placed in the same apparatus as in Example 1, and 77.5 g of carbon disulfide was added under the same conditions as in Example 2.
g was added and reacted to obtain a reaction product. To this reaction product, the amounts of sodium pentasulfide and pure water shown in Table 1 were added to make a 2wt% aqueous solution, and then the above 2wt% aqueous solution was added to 1000ml each of the same four types of metal ion-containing aqueous solutions as in Example 1. The amount shown in Table 1 was added, and the flocculation time, flocculation amount, and residual metal ion concentration in the liquid were measured in the same manner as in Example 1. The results are also shown in Table 1.

【table】

〔Effect of the invention〕

As explained above, the metal collection method of the present invention uses a polyamine having as a substituent at least one carbodithioic acid group and/or a salt thereof substituted with an active hydrogen atom of a polycondensed polyamine obtained by polycondensing a polyamine and an epihalohydrin. A method was adopted for collecting and removing metal ions in wastewater by adding the derivative and at least one of sodium monosulfide, sodium polysulfide, and sodium hydrogen sulfide to wastewater containing metal ions as a metal collecting agent. from,
Compared to conventional metal collectors containing aliphatic polydithiocarbamic acids or salts thereof, metal ions in wastewater can be sufficiently collected and removed with a smaller amount added.
Furthermore, even when the polyamine derivative used in the present invention is used alone as a metal scavenger, the flocs generated by capturing metals are large and the sedimentation rate of the flocs is fast, so that metal ions in wastewater can be quickly captured. However, when used in combination with at least one of sodium monosulfide, sodium polysulfide, and sodium hydrogen sulfide, the two act synergistically, resulting in even more floc removal than when polyamine derivatives are used alone. It has a fast sedimentation rate and is effective in collecting and removing metal ions in wastewater extremely efficiently.

Claims (1)

[Scope of Claims] 1. A polyamine derivative having as a substituent at least one carbodithioic acid group and/or a salt thereof substituted with an active hydrogen atom of a polycondensed polyamine obtained by polycondensation of a polyamine and an epihalohydrin, and sodium monosulfide. A method for collecting metals, which comprises adding at least one of sodium polysulfide, sodium polysulfide, and sodium hydrogen sulfide to wastewater containing metal ions to collect and remove metal ions in the wastewater. 2. The metal according to claim 1, wherein the polyamine derivative has at least one type selected from the group consisting of an alkyl group, a hydroxyalkyl group, and an acyl group as an N-substituent bonded to the nitrogen atom of the polycondensed polyamine. Collection method.