JP3373023B2 - Metal scavenger - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal collecting agent. 2. Description of the Related Art Strict regulations have been set for metals contained in wastewater and the like, particularly heavy metals such as mercury, cadmium, zinc, lead, copper and chromium which are harmful to the human body. Various methods have been studied to remove the metals contained in. For example, neutralization coagulation sedimentation, or ion flotation, in which an alkali such as slaked lime or sodium hydroxide is added to wastewater to convert the metal in the wastewater to hydroxide and then coagulate and precipitate with a polymer coagulant, Ion exchange method, electrolytic levitation method,
Electrodialysis, adsorption, reverse osmosis, and the like are known. [0004] However, in the neutralization coagulation sedimentation method, a large amount of metal hydroxide sludge is generated, the sludge has poor dewaterability, and the sludge volume is large. ) Is bad, and depending on the method of disposal of sludge, there is a problem that the metal is re-eluted into rivers and seawater to cause secondary pollution. In addition, it was not easy to remove the metal concentration in wastewater below the national standard by the neutralization coagulation sedimentation method. On the other hand, methods such as an ion flotation method, an ion exchange method, an electrolytic flotation method, an electrodialysis method, an adsorption method, and a reverse osmosis method also have problems in metal removal rate, operability, running cost, and the like. It was used only for some special wastewater treatment. For this reason, in recent years, a method of collecting and removing metals in wastewater with a metal collecting agent has been widely used instead of the above method. As a metal collecting agent used for wastewater treatment, a compound having a dithioacid group or a dithioacid group as a functional group is known. The present applicant has set forth that the sedimentation rate of flocs formed by collecting metals is high and that wastewater treatment can be performed efficiently, and polyalkylene polyamines such as ethylenediamine, diethylenetriamine and triethylenetetramine, and polyethyleneimine And a metal trapping agent having a structure in which a dithioic acid group or a dithioic acid group is bonded to a nitrogen atom of a polyamine such as a polyamine, and a wastewater treatment method using the collecting agent. 60-1
7128, JP-A-2-81478, etc.). [0007] In recent years, not only the treatment of metals in wastewater but also the treatment of metals contained in gases such as waste gas, incineration ash, sludge, slag, and pollutants have been recently carried out. The use of metal trapping agents for the treatment of metals contained in solid waste such as soil has been studied, and various studies and improvements have been made. Conventional metal scavengers can also theoretically be used for the treatment of waste gases and solid waste containing metals, and at the laboratory level, many good results have already been obtained, In practical use, there are still many problems to be solved. For example, when a gasified metal (metal compound) contained in waste gas is collected and removed by a metal collecting agent, the metal collecting agent is exposed to a high temperature of 150 to 300 ° C. For this reason, the metal collector is required to have heat resistance. In the case of treating solid waste containing metal, in the laboratory, a sufficient amount of stirring is performed after the addition of the metal collecting agent to ensure that the solid waste and the metal collecting agent are mixed. When solid waste is actually treated, the conditions are not always such that sufficient stirring can be performed at any time. For this reason, in order to use a metal collecting agent for treating actual waste gas or solid waste, it is required that the metal collecting agent has excellent heat resistance and high permeability to a solid substance. You. However, conventional metal scavengers cannot be said to have sufficient heat resistance and permeability into solids, and are still insufficient for application to the treatment of waste gas and solid waste on an industrial scale. Met. The present invention has been made in view of the above points,
In addition to having excellent performance for collecting metal in wastewater, it also has excellent heat resistance and excellent permeability to solid waste, and has excellent performance for treating metals in waste gas and fixing metals in solid substances. An object of the present invention is to provide a metal collecting agent that exerts its effect. [0010] That is, the metal scavenger of the present invention comprises at least one carbon atom bonded to a nitrogen atom in a copolymer of a polyamine and a compound represented by the following formula (2). It has a dithioacid group and / or a dithioacid group as a functional group. [0011] In the present invention, examples of the dithioacid base include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts, and ammonium salts. The polyamines which are one of the constituents constituting the molecular skeleton of the metal scavenger of the present invention include, for example, ethylenediamine, propylenediamine, butylenediamine, and the like.
Hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine, tripropylenetetramine, tribubutyltetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine, pentaethylenehexamine, iminobispropylamine, Aliphatic polyamines such as monomethylaminopropylamine, methyliminobispropylamine, 1,3-diaminopropane, and 1,4-diaminobutane; phenylenediamine, o-, m-,
aromatic polyamines such as p-xylenediamine and 3,5-diaminochlorobenzene; cycloalkane-based polyamines such as 1,3-bis (aminomethyl) cyclohexane; polyethyleneimine, polypropyleneimine, poly-2-methylethyleneimine, poly- 2-ethylethyleneimine, poly-
Polymers of cyclic imines such as 3-methylpropyleneimine, poly-3-ethylpropyleneimine, poly-2-methylpropyleneimine and poly-2-ethylpropyleneimine, and polymers of unsaturated amines such as polyvinylamine and polyallylamine An unsaturated amine such as vinylamine and allylamine, and a copolymerizable unsaturated bond such as dimethylacrylamide, styrene, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene sulfonic acid, and the like, and salts thereof. And a copolymer with the above monomer. When a polymer of a cyclic imine, a polymer of an unsaturated amine and a copolymer thereof are used, the average molecular weight is 300.
２００200,000 is preferable, and ５０500,000 is more preferable. The above polyamines have an alkyl group, β
Those obtained by introducing a -hydroxyalkyl group, an acyl group, an alkylphenyl group, an alkyl-substituted hydroxyalkyl group, or the like as an N-substituent can also be used. Compounds represented by the above formula 2 which are polymerized with polyamines include cyclic compounds containing oxygen, sulfur, and nitrogen, such as epoxy compounds, cyclic sulfide compounds, cyclic ethers, cyclic formals, and N-substituted alkylene imines. A compound obtained by reacting a homopolymer or copolymer of a compound with epihalohydrin or formaldehyde, a compound having an epoxy group or an aldehyde group at one end, or an epoxy group and / or an aldehyde group at both ends. Compounds. The compound represented by Chemical formula 2 preferably has a molecular weight of about 500,000 or less, particularly preferably 500,000 to 200,000. The subscript “m” in the general formula shown in Chemical formula 2 is a positive integer in which the molecular weight of the compound of Chemical formula 2 is within the above range. The epoxy compound is an epoxy compound represented by the following chemical formula 3, and examples thereof include ethylene oxide, propylene oxide, and 1,2-epoxyalkane. Embedded image As the cyclic sulfide compound, a compound represented by the following formula (4) having a structure in which oxygen and sulfur of the epoxy group of the above epoxy compound are substituted, and examples thereof include ethylene sulfide and propylene sulfide. Embedded image The cyclic ethers include oxetane, mono- or bisalkyl (alkyl group having 1 to 5 carbon atoms) oxetane, mono- or bischloromethyloxetane, tetrahydrofuran, mono- or bisalkyl (alkyl group having 1 to 5 carbon atoms) tetrahydrofuran And the like. Examples of the cyclic formal include compounds such as 1,3-dioxolane represented by the following formula (5) and trioxane. Embedded image Further, as the N-substituted alkyleneimine,
A compound represented by the following formula 6 is exemplified. Embedded image The copolymer constituting the molecular chain of the metal-collecting agent of the present invention has a structure in which the polyamine and at least one molecule of the compound represented by the above formula (2) are polymerized.
When two or more molecules of the compound of the formula (2) are copolymerized with the polyamines, the compounds of the formula (2) may be the same kind of compound or different kinds of compounds. There are various methods for producing the metal scavenger of the present invention. For example, after a polyamine is copolymerized with a compound represented by the formula (2), the copolymer is mixed with carbon disulfide. To introduce a dithioacid group by reacting After the dithioacid group is introduced, the metal collector having a dithioacid group is treated with an alkali such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide, or reacted with carbon disulfide in the presence of these alkalis. can get. The metal collector of the present invention can also be obtained by a method of copolymerizing a polyamine into which a dithioacid group and / or a dithioacid group has been introduced in advance and a compound of the formula (2). The metal trapping agent of the present invention is generated during waste incineration in wastewater discharged from factories and garbage disposal plants, waste gas discharged from garbage incineration plants, thermal power plants, etc., or garbage incineration plants. Fly ash (Depending on the method of dust collection, MC
Ash, EP ash, cyclone ash, scrubber ash, bag filter ash and the like. ) And incinerated ash such as residual ash, slag discharged from mines, sludge in wastewater treatment plants, and the like, or metals contained in solid waste such as contaminated soil such as factory sites. . As a method of treating wastewater with the metal collecting agent of the present invention, the collecting agent of the present invention is added to waste water, and the floc generated by the collecting agent of the present invention collecting metals in the waste water. A method of separating from wastewater by precipitation filtration is adopted.
Wastewater from which flocs have been separated and removed can be discharged to rivers and the like. When the wastewater is treated with the collecting agent of the present invention, it is preferable to adjust the pH of the wastewater to about 3 to 12 in order to enhance the metal collecting effect. To adjust the pH of the wastewater, acids such as hydrochloric acid, sulfuric acid and nitric acid, and alkalis such as sodium hydroxide and potassium hydroxide are used. As a method of treating the waste gas, a method of diluting the trapping agent into water in the waste gas and introducing the same into the waste gas or introducing the trapping agent together with the acidic gas adsorbent is employed. As a method for treating the solid waste, the metal-collecting agent of the present invention or an aqueous solution thereof is sprayed on the surface of the solid waste to infiltrate the metal-collecting agent into the solid waste, A method in which a collecting agent and, if necessary, a small amount of water are added to the solid waste and kneaded is adopted. In the treatment of solid waste, it is preferable to use an acidic substance or an alkaline substance as needed. When a solid waste containing a metal is treated with the collecting agent of the present invention, the metal in the solid substance is fixed by the metal collecting agent of the present invention and becomes difficult to elute from the solid substance. Objects can be dumped underground or underwater. The metal trapping agent of the present invention can be used for treating wastewater, waste gas, and solid waste, such as trimercaptotriazine or salts thereof, sodium monosulfide, sodium hydrogensulfide,
It can be used in combination with at least one kind of sodium polysulfide such as sodium disulfide, sodium trisulfide, sodium tetrasulfide and sodium pentasulfide. When these compounds are used in combination with the metal-collecting agent of the present invention, the metal-collecting efficiency is enhanced. Among them, the use of sodium hydrogen sulfide and sodium polysulfide is particularly preferable. When the metal scavenger of the present invention is used in combination with the above sodium hydrogen sulfide and sodium polysulfide in the treatment of solid waste, the amount of the metal scavenger used is smaller than when the metal scavenger is used alone. At the same time, the bond between the metal collecting agent and the metal is strengthened, so that the metal can be securely fixed. The metal-collecting agent of the present invention is excellent in collecting performance of mercury, cadmium, zinc, copper, chromium, arsenic, gold, silver, platinum, vanadium, thallium and the like, and the compound of the present invention. The collector is suitable for treating wastewater, waste gas and solid waste containing these. The present invention will be described below in more detail with reference to examples. Examples 1 and 2 Polyethylene oxide (molecular weight 300,000 in Example 1, molecular weight 3000 in Example 2) and epichlorohydrin were used to react with a compound having an epoxy group at the terminal of polyethylene oxide. Metals obtained by reacting carbon disulfide with a copolymer obtained by copolymerizing the compounds at a reaction ratio (% by weight) shown in Table 1 to introduce a dithioic acid group (or a sodium dithioate base) as a functional group. An agent (aqueous solution) was obtained. Type of polyamine used, reaction ratio of polyamines, substitution rate of functional group (substitution rate of functional group substituted with active hydrogen bonded to nitrogen atom in copolymer)
Are shown in Table 1. Table 1 also shows the content of the solid metal trapping agent in each of the obtained metal trapping agents (aqueous solutions).
In Example 2, the reaction between the copolymer and carbon disulfide was carried out in the presence of sodium hydroxide to introduce a sodium dithioate base as a functional group. Using each of the obtained metal trapping agents, Hg ²⁺ was ^reduced to 2
PH containing 3 mg / l, Pb ²⁺ 20 mg / l, Ni ²⁺ 37 mg / l, Zn ²⁺ 29 mg / l
= 1 to 1 liter of wastewater, a metal collecting agent (aqueous solution) was added so that 30 mg of the metal collecting agent was added as a solid component, and the mixture was stirred for 10 minutes, and then allowed to stand still to generate floc. The time required for flocking (flock sedimentation time), the amount of flocs produced, and the concentration of metal ions remaining in the wastewater after removing the flocs were measured. Table 2 shows the results. [Table 1] [Table 2] The floc sedimentation time was defined as the time at which the interface between the floc and water disappeared, and the generated floc amount was defined as the floc amount at the time of the floc sedimentation time. The concentration of residual metal ions in the wastewater was measured by atomic absorption spectrometry. Further, a dissolution test of metal ions from the formed flocs was performed. The dissolution test of metal ions from flocs was carried out based on the method of Notification No. 13 of the Environment Agency. The results are shown in Table 2. Examples 3 and 4 Polypropylene sulfide (Example 3 has a molecular weight of 100
0, Example 4 used a molecular weight of 3500) and a compound having a methylol group at the polypropylene sulfide end obtained by reacting formaldehyde with a polyamine at a reaction ratio (% by weight) shown in Table 1. The copolymer thus obtained was reacted with carbon disulfide to obtain a metal collecting agent (aqueous solution) having a dithioic acid group (or sodium dithioate) introduced as a functional group. Table 1 shows the types of the polyamines used, the reaction ratios of the polyamines, and the substitution rates of the functional groups (the substitution rates of the functional groups substituted with the active hydrogen bonded to the nitrogen atom in the copolymer). Table 1 also shows the content of the solid components of the metal collecting agent (aqueous solution) obtained. In Example 3, the reaction between the copolymer and carbon disulfide was carried out in the presence of sodium hydroxide to introduce a sodium dithioate base as a functional group. Examples 1 and 2 using the obtained metal collecting agent
A water treatment test and a metal elution test from flocs were carried out in the same manner as described above. Table 2 shows the results. Examples 5 and 6 Tetrahydrofuran polymer (Example 5 has a molecular weight of 500
0, Example 6 uses a molecular weight of 2,000) and epichlorohydrin, and reacts polyamines at a reaction ratio (% by weight) shown in Table 1 with respect to a compound having an epoxy group at a terminal of a tetrahydrofuran polymer. The copolymer obtained by the copolymerization was reacted with carbon disulfide to obtain a metal collector (aqueous solution) in which a dithioic acid group (or a sodium dithioate base) was introduced as a functional group. Table 1 shows the types of the polyamines used, the reaction ratios of the polyamines, and the substitution rates of the functional groups (the substitution rates of the functional groups substituted with the active hydrogen bonded to the nitrogen atom in the copolymer). Table 1 also shows the content of the solid components of the metal collecting agent (aqueous solution) obtained. In Example 5, the reaction between the copolymer and carbon disulfide was carried out in the presence of sodium hydroxide to introduce a sodium dithioate base as a functional group. Examples 1 and 2 using the obtained metal collecting agent
A water treatment test and a metal elution test from flocs were carried out in the same manner as described above. Table 2 shows the results. Examples 7 and 8 Compounds having an epoxy group at the end of a trioxane polymer obtained by reacting a trioxane polymer (Example 7 uses a molecular weight of 13000 and Example 8 uses a molecular weight of 2300) with epichlorohydrin On the other hand, a copolymer obtained by copolymerizing polyamines at a reaction ratio (% by weight) shown in Table 1 was reacted with carbon disulfide to introduce a dithioic acid group (or a sodium dithioate base) as a functional group. The obtained metal collector (aqueous solution) was obtained. Table 1 shows the types of the polyamines used, the reaction ratios of the polyamines, and the substitution rates of the functional groups (the substitution rates of the functional groups substituted with the active hydrogen bonded to the nitrogen atom in the copolymer). Table 1 also shows the content of the solid components of the metal collecting agent (aqueous solution) obtained.
In Example 7, the reaction between the copolymer and carbon disulfide was carried out in the presence of sodium hydroxide to introduce a sodium dithioate base as a functional group. Examples 1 and 2 using the obtained metal collecting agent
A water treatment test and a metal elution test from flocs were carried out in the same manner as described above. Table 2 shows the results. Examples 9 and 10 n-methylethyleneimine polymer (Example 9 has a molecular weight of 2
5000, Example 10 uses a molecular weight of 40000)
The reaction ratio (% by weight) of polyamines to the compound having an epoxy group at the terminal of the n-methylethyleneimine polymer obtained by reacting with epichlorohydrin is shown in Table 1.
The resulting copolymer was reacted with carbon disulfide to obtain a metal collector (aqueous solution) in which a dithioic acid group (or a sodium dithioate base) was introduced as a functional group. Table 1 shows the types of the polyamines used, the reaction ratios of the polyamines, and the substitution rates of the functional groups (the substitution rates of the functional groups substituted with the active hydrogen bonded to the nitrogen atom in the copolymer). Table 1 also shows the content of the solid components of the metal collecting agent (aqueous solution) obtained. In Example 10, the reaction between the copolymer and carbon disulfide was carried out in the presence of sodium hydroxide to introduce a sodium dithioate base as a functional group. Examples 1 and 2 using the obtained metal collecting agent
A water treatment test and a metal elution test from flocs were carried out in the same manner as described above. Table 2 shows the results. COMPARATIVE EXAMPLE 1 Two moles of carbon disulfide were reacted per mole of ethylenediamine, and a metal scavenger in which dithioic acid groups were introduced at a substitution rate of 50% with active hydrogen bonded to the nitrogen of ethylenediamine was used as a solid. An aqueous solution containing 5% by weight of the mold component was obtained. The same test as in Examples 1 and 2 was performed using this metal collecting agent.
The results are shown in Table 2. Comparative Example 2 2 moles of carbon disulfide per mole of m-xylenediamine
The moles were reacted to obtain an aqueous solution containing, as solid matter, 8% by weight of a metal collector in which a dithioic acid group was introduced at a substitution rate of 50% with active hydrogen bonded to m-xylenediamine nitrogen. The same test as in Examples 1 and 2 was performed using this metal collecting agent. The results are shown in Table 2. COMPARATIVE EXAMPLE 3 0.4 mol of carbon disulfide was reacted with respect to 1 monomer unit of polyethyleneimine (molecular weight: 20,000), and the dithioic acid group was replaced with active hydrogen bonded to the nitrogen of polyethyleneimine at a substitution rate of 40%. The amount of the introduced metal collector is 1
An aqueous solution containing 0% by weight was obtained. The same test as in Examples 1 and 2 was performed using this metal collecting agent. The results are shown in Table 2. COMPARATIVE EXAMPLE 4 The mixed metal collecting agent obtained by mixing the metal collecting agent used in Comparative Example 1 and the metal collecting agent used in Comparative Example 3 at a weight ratio of 9: 1 was used. The same tests as in Examples 1 and 2 were performed. The results are shown in Table 2. Examples 11 to 20, Comparative Examples 5 to 8 Using the same metal collecting agent as used in Examples 1 to 10 and Comparative Examples 1 to 4, Pb was 5200 mg / kg, and Cd was 1850.
To 50 g of fly ash (EP ash) obtained from a garbage incineration plant containing 25 mg / kg of Hg and 25 mg / kg of Hg and 173 mg / kg of Cu, a metal collecting agent (aqueous solution) was added in an amount of 0%. The mixture was added so as to be 0.5 g, and kneaded well for 20 minutes. 50 g of the fly ash after the treatment as described above was shaken in 500 ml of pure water adjusted to pH = 5 at room temperature for 100 minutes to conduct a dissolution test of uncollected metals. Table 3 shows the results obtained by measuring the concentration of metal ions eluted in water by atomic absorption spectrometry. The same test as described above was performed on untreated fly ash that had not been treated with a metal collecting agent (Reference Example 1). Table 3 shows the results. [Table 3] Examples 21 to 30, Comparative Examples 9 to 12 Using the same metal collecting agent as used in Examples 1 to 10 and Comparative Examples 1 to 4, 1850 mg / kg of Cr and 960 mg of Ni
/ G, 65 mg / kg As, 1650 mg / kg Fe, 80 g of slag containing a metal collector (aqueous solution) was sprayed onto the surface of the slag so that the added amount of the solid component became 0.6 g, and the mixture was sprayed for 100 minutes. I left it. Mineral slag 5 treated as above
0 g was shaken at room temperature for 60 minutes in 500 ml of pure water adjusted to pH = 7 to conduct a dissolution test of uncollected metals. Table 4 shows the results of measuring the concentration of metal ions eluted in water by atomic absorption spectrometry. In addition, the same test as above was performed on untreated slag that had not been treated with a metal collecting agent (Reference Example 2). The results are shown in Table 4. [Table 4] Examples 31 to 40 and Comparative Examples 13 to 16 Using the same metal collecting agent as used in Examples 1 to 10 and Comparative Examples 1 to 4, 190 mg / kg of Pb and 52 mg / k of Hg were used.
g, 110 mg / kg of Cr, 550 mg / kg of Fe, 35 mg / kg of Cu, 70 g of sludge (water content: 85%) on the surface of which a metal trapping agent (aqueous solution) was added to the solid component. Is 0.
It was sprayed to 1 g and left for 80 minutes. 50 g of the treated sludge treated as described above was taken at room temperature in 500 ml of pure water adjusted to pH = 6.
The sample was shaken for a minute to perform an elution test of uncollected metals. The results obtained by measuring the concentration of metal ions eluted in water by atomic absorption spectrometry are shown in Table 5. In addition, the same test as above was performed on untreated sludge that had not been treated with a metal collecting agent (Reference Example 3). The results are shown in Table 5. [Table 5] Examples 41 to 50, Comparative Examples 17 to 20 Using the same metal collecting agent as used in Examples 1 to 10 and Comparative Examples 1 to 4, Hg was 1 mg / Nm ³ and dust was 3 g / N.
260 ° C waste gas containing m ³ (30 Nm ³ / hour)
Then, a metal collecting agent diluted with water was sprayed into a flue at a rate of 3 mg / hour as a solid component, reacted, and then collected by a back filter. Table 6 shows the results of measuring the Hg concentration in the waste gas after spraying the metal collector diluted with water. [Table 6] The metal scavenger of the present invention, when used for wastewater treatment, is a dithioic acid group or a dithioic acid base introduced by replacing an active hydrogen atom bonded to nitrogen of polyamines. As compared with the conventional metal collecting agent having the above, the floc generated by the metal collecting agent of the present invention by collecting the metal ions in the wastewater has a high sedimentation property, and the wastewater treatment can be performed efficiently. Further, the collecting agent of the present invention has a lower re-elution property of the metal from the generated floc than the conventional collecting agent, and can reliably collect and remove metal ions in wastewater. Further, since the metal collecting agent of the present invention has higher heat resistance than conventional ones, metals contained in high-temperature waste gas can be collected and removed efficiently. When the collector of the present invention is used for treating solid waste such as incineration ash, slag, sludge, soil and the like containing metals, the collector of the present invention permeates solid waste. The metal contained in these solid substances can be immobilized reliably and efficiently, and the binding agent of the present invention has a high binding force with the metal. Has the effect that there is no danger that the metal will be eluted from the solid substance by being removed.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Ogawa 4-66-1, Horikiri, Katsushika-ku, Tokyo Miyoshi Oil & Fats Co., Ltd. (72) Inventor Tsuyoshi Shimizu 4-66-1, Horikiri, Katsushika-ku, Tokyo Miyo Inside the Shi Oil & Fat Co., Ltd. (72) Inventor Masaki Arame 1366 Nishiide, Noyoro-cho, Iwakura-shi, Aichi Miyoshi Oil & Fat Co., Ltd. Nagoya Plant (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 20/00 -20/34

Claims (1)

(57) [Claim 1] At least one dithioic acid group and / or dithioic acid bonded to a nitrogen atom in a copolymer of a polyamine and a compound represented by the following formula 1 A metal collector having a base as a functional group. Embedded image