Heavy metal treatment agent, and method for treating incinerated ash and wastewater using same

Abstract

Provided are: a novel heavy metal treatment agent having improved performance for treating elements of groups 6-16 of the periodic table or compounds thereof, including treatment of incinerated ash and wastewater, etc.; and a method for treating incinerated ash and wastewater using the heavy metal treatment agent.　This heavy metal treatment agent includes at least one dithiocarbamate among amine compounds represented by any of formulas (I) to (III). Formula (I) (In the formula, m represents an integer of 3-6.) Formula (II) (In the formula, each of the n X independently represents a hydrogen atom or a 2-aminoethyl group, at least one X being a 2-aminoethyl group, n represents an integer of 1-3, and the total number of nitrogen atoms is 4-8.) Formula (III) (In the formula, o represents an integer of 0-2, p represents 0 or 1, q represents 0 or 1, r represents an integer of 0-3, the sum of o, p, and r is 1 or greater, and the total number of nitrogen atoms is 3-7.)

Description

Heavy metal treatment agent and incineration ash and wastewater treatment method using the same

[0001] The present invention relates to a heavy metal treatment agent.

[0002] Incineration ash (fly ash and bottom ash) generated during the incineration of municipal solid waste, industrial waste, and other waste may contain heavy metals that are harmful to the human body. For example, fly ash generated during incineration at municipal solid waste incineration facilities contains heavy metals. If these heavy metals leach into groundwater, rivers, or seawater, they can cause serious environmental pollution. Therefore, fly ash is treated as specially controlled municipal waste and is required to undergo intermediate treatment, such as chemical treatment. Since heavy metals leach into rainwater and other sources after landfill disposal, methods are commonly used to immobilize the heavy metals in the fly ash to prevent their leaching. Chemical treatment involves mixing chemicals with water and the fly ash to immobilize the harmful heavy metals. Chemicals used for this purpose include organic chelating agents such as dithiocarbamates and inorganic chemicals such as iron compounds.

[0003] Various treatments have been performed to separate and recover heavy metals from industrial wastewater, business wastewater, and other waters for purposes such as water purification, detoxification, and reuse of the heavy metals. Conventional methods for removing metals from wastewater include, for example, neutralization coagulation sedimentation, ion flotation, ion exchange, electrolytic flotation, electrodialysis, adsorption, and reverse osmosis. However, neutralization coagulation sedimentation has problems such as insufficient floc formation, the need to treat large amounts of metal hydroxide sludge produced, the re-elution of metal ions from the discarded sludge into rivers, seawater, and other sources, causing secondary pollution, and the difficulty of maintaining metal ion concentrations in wastewater below nationally established standards. Furthermore, ion flotation, ion exchange, electrolytic flotation, electrodialysis, adsorption, and reverse osmosis have problems with metal removal rates, operability, running costs, and the like. For these reasons, methods of capturing and removing metals from wastewater using metal collectors, such as organic chelating agents, have become widely used instead of these methods.

[0004] Conventionally, dithiocarbamates derived from amine compounds such as ethylenediamine, diethylenetriamine, and piperazine have been used as heavy metal treatment agents (metal scavengers) to treat heavy metals contained in incineration ash (fly ash and bottom ash), wastewater, and the like (Patent Documents 1 and 2).

[0005] JP-A No. 6-79254 JP-A No. 8-224560

[0006] However, in the prior art, further improvements have been desired in the heavy metal treatment performance of incineration ash treatment, wastewater treatment, etc., particularly in the suppression of elution from incineration ash in incineration ash treatment, and in the heavy metal capture performance and floc formation ability in wastewater treatment.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel heavy metal treatment agent having improved performance in treating elements of Groups 6 to 16 of the periodic table or compounds thereof in incineration ash treatment, wastewater treatment, and the like, and a method for treating incineration ash and wastewater using the same.

[0008] In order to solve the above problems, the following invention is disclosed: [1] A heavy metal treatment agent comprising at least one dithiocarbamate salt of an amine compound represented by any one of the following formulas (I) to (III): (In the formula, m represents an integer of 3 to 6.) (In the formula, n Xs each independently represent a hydrogen atom or a 2-aminoethyl group, at least one of which is a 2-aminoethyl group, n represents an integer of 1 to 3, and the total number of nitrogen atoms is 4 to 8.) (wherein o is an integer of 0 to 2, p is 0 or 1, q is 0 or 1, r is an integer of 0 to 3, the sum of o, p and r is 1 or more, and the total number of nitrogen atoms is 3 to 7.) [2] The heavy metal treatment agent according to [1] above, wherein the amine compound comprises an amine compound represented by formula (III). [3] The heavy metal treatment agent according to [2] above, wherein the amine compound represented by formula (III) comprises at least one selected from the group consisting of amine compounds represented by the following formulas (IIIa), (IIIb) and (IIIc): [4] The heavy metal treatment agent according to [2] or [3], wherein the amine compound represented by formula (III) includes each of the amine compounds represented by the following formulas (IIIa) and (IIIb): [5] The heavy metal treatment agent according to [4], wherein the amine compound further contains an amine compound represented by the following formula (IIIc) as the amine compound represented by the formula (III): [6] The heavy metal treatment agent according to any one of [1] to [5], wherein the amine compound contains each of the amine compounds represented by formula (I), formula (II), and formula (III). [7] The heavy metal treatment agent according to [6], wherein the amine compound contains each of the amine compounds represented by the following formulas (Ia), (IIa), (IIIa), and (IIIb) as the amine compound represented by any of formulas (I) to (III). [8] The heavy metal treatment agent according to [7], wherein the amine compound further contains an amine compound represented by the following formula (IIIc) as the amine compound represented by the formula (III): [9] The heavy metal treatment agent according to any one of [1] to [8], wherein the amine compound comprises an amine compound represented by formula (III), and the amount of the amine compound represented by formula (III) is 10.0% or more and 80.0% or less.

[10] The heavy metal treatment agent according to any one of [1] to [9], wherein the amine compound comprises, as the amine compound represented by formula (III), amine compounds represented by the following formulas (IIIa) and (IIIb), and the total amount of the amine compound represented by formula (IIIa) and the amine compound represented by formula (IIIb) is 10.0% or more and 50.0% or less.

[11] The heavy metal treatment agent according to any one of [1] to

[10] , wherein the amine compound comprises an amine compound represented by formula (II), and the amount of the amine compound represented by formula (II) is 5.0% or more and 30.0% or less.

[12] The heavy metal treatment agent according to any one of [1] to

[11] , wherein the dithiocarbamate is dithiocarbamic acid sodium salt.

[13] The heavy metal treatment agent according to any one of [1] to

[12] , wherein the treatment target is an element of Groups 6 to 16 of the periodic table or a compound thereof.

[14] A method for treating incineration ash containing at least any one of elements of Groups 6, 12, and 14 of the periodic table or a compound thereof, comprising a step of adding the heavy metal treatment agent according to any one of [1] to

[13] to incineration ash.

[15] The method for treating incineration ash according to

[14] , wherein the pH of the eluate of the incineration ash in the Environment Agency's No. 13 test is 11.5 or more.

[16] A method for treating wastewater containing an element of Groups 6 to 16 of the periodic table or a compound thereof, comprising the step of adding to the water to be treated a heavy metal treatment agent according to any one of [1] to

[13] above, and an iron-based inorganic flocculant and / or an aluminum-based inorganic flocculant.

[17] A method for treating wastewater containing an element of Groups 6 to 16 of the periodic table or a compound thereof, comprising the step of adding to the water to be treated a heavy metal treatment agent according to any one of [1] to

[13] above, and a polymer flocculant.

[18] A method for treating wastewater containing an element of Groups 6 to 16 of the periodic table or a compound thereof, comprising the step of adding to the water to be treated a heavy metal treatment agent according to any one of [1] to

[13] above, a polymer flocculant, and an iron-based inorganic flocculant and / or an aluminum-based inorganic flocculant.

[0009] According to the present invention, a novel heavy metal treatment agent is provided which has improved treatment performance for elements of Groups 6 to 16 of the periodic table or compounds thereof in incineration ash treatment, wastewater treatment, and other processes, and which has, in particular, improved ability to inhibit heavy metal elution from incineration ash in incineration ash treatment, and improved heavy metal capture ability and flocculation ability in wastewater treatment. Furthermore, by using this novel heavy metal treatment agent in a method for treating incineration ash containing elements of Groups 6 to 16 or compounds thereof, a method for treating incineration ash in which the ability to inhibit heavy metal elution from incineration ash is improved is provided. By using this novel heavy metal treatment agent in a method for treating wastewater containing elements of Groups 6 to 16 or compounds thereof, a method for treating wastewater in which the heavy metal capture ability and flocculation ability are improved is provided.

[0010] Specific embodiments of the present invention are described below. The heavy metal treatment agent of the present invention contains at least one dithiocarbamate salt of an amine compound represented by any one of formulas (I) to (III). In the present invention, "at least one dithiocarbamate salt of an amine compound" means "a dithiocarbamate salt produced using at least one amine compound as a raw material." A dithiocarbamate salt is a compound in which the hydrogen atom bonded to the nitrogen atom of the raw material amine compound is substituted with a dithiocarbamate salt.

[0011] The amine compound represented by formula (I) is linear. In the formula, m represents an integer of 3 to 6. From the viewpoints of excellent treatment of elements of Groups 6 to 16 of the periodic table or compounds thereof, and in addition, excellent stability of dithiocarbamate salts in heavy metal treatment agents and / or excellent floc formation in wastewater treatment, m is preferably 3 to 5, more preferably 3 to 4, and even more preferably 4. The amine compounds represented by formula (I) may be used alone or in combination of two or more.

[0012] The amine compound represented by formula (I) is not particularly limited, and examples thereof include triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, etc. Among these, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine are preferred, triethylenetetramine and tetraethylenepentamine are more preferred, and tetraethylenepentamine is even more preferred, because they are excellent in treating elements of Groups 6 to 16 of the periodic table or compounds thereof, and in addition, they are excellent in at least one of the stability of dithiocarbamate salts in heavy metal treatment agents and floc formation in wastewater treatment.

[0013] The amine compound represented by formula (II) is branched. In the formula, n Xs each independently represent a hydrogen atom or a 2-aminoethyl group, at least one of which is a 2-aminoethyl group, n represents an integer of 1 to 3, and the total number of nitrogen atoms is 4 to 8. From the viewpoints of excellent treatment of elements of Groups 6 to 16 of the periodic table or compounds thereof, and in addition, excellent at least one of the stability of dithiocarbamate salts in heavy metal treatment agents and floc formation in wastewater treatment, n is preferably 1 to 2, and more preferably 2. Preferably, the total number of nitrogen atoms is 4 to 6, and more preferably 5. The amine compounds represented by formula (II) may be used alone or in combination of two or more.

[0014] The amine compound represented by formula (II) is not particularly limited, and examples thereof include tris(2-aminoethyl)amine, N,N,N'-tris(2-aminoethyl)ethane-1,2-diamine, N,N,N',N'-tetra(2-aminoethyl)ethane-1,2-diamine, N,N-bis-(2-aminoethyl)-N'-[2-[(2-aminoethyl)amino]ethyl]ethane-1,2-diamine, N 1-(2-[(2-aminoethyl)-[2-[(2-aminoethyl)amino]ethyl]amino]ethyl)ethane-1,2-diamine, N,N'-bis-(2-aminoethyl)-N-[2-[bis-(2-aminoethyl)amino]ethyl]ethane-1,2-diamine, N,N-bis-(2-aminoethyl)-N'-[2-[bis-(2-aminoethyl)amino]ethyl]ethane-1,2-diamine, and the like. Among these, tris(2-aminoethyl)amine, N,N,N'-tris(2-aminoethyl)ethane-1,2-diamine, and N,N,N',N'-tetra(2-aminoethyl)ethane-1,2-diamine are preferred, and N,N,N'-tris(2-aminoethyl)ethane-1,2-diamine is more preferred, because they are excellent in treating elements of Groups 6 to 16 of the periodic table or compounds thereof, and in addition, they are excellent in at least one of the stability of dithiocarbamate salts in heavy metal treatment agents and floc formation in wastewater treatment.

[0015] The amine compound represented by formula (III) is a combination of cyclic and linear structures, in which o is an integer of 0 to 2, p is 0 or 1, q is 0 or 1, and r is an integer of 0 to 3, the sum of o, p, and r is 1 or more, and the total number of nitrogen atoms is 3 to 7.

[0016] In view of excellent treatment of elements of Groups 6 to 16 of the periodic table or compounds thereof, and in addition excellent stability of dithiocarbamate in heavy metal treatment agents and / or excellent floc formation in wastewater treatment, preferably, o is 0 or 1, p is 0 or 1, q is 0 or 1, and r is an integer of 0 to 3. More preferably, o is 0 or 1, p is 0, q is 0 or 1, and r is an integer of 0 to 3. Even more preferably, o is 0 or 1, p is 0, q is 0, and r is an integer of 2 to 3. Meanwhile, the total number of nitrogen atoms is preferably 3 to 6, more preferably 4 to 5, and even more preferably 5. The amine compounds represented by formula (III) may be used alone or in combination of two or more.

[0017] The amine compound represented by formula (III) is not particularly limited, and examples thereof include aminoethylpiperazine, piperazine-1,4-diethylamine, N-(2-(1-piperazinyl)ethyl)ethylenediamine, N-[2-[4-(2-aminoethyl)piperazin-1-yl]ethyl]ethane-1,2-diamine, N-(2-aminoethyl)-N'-[2-(piperazin-1-yl)ethyl]ethane-1,2-diamine, 4-[2-(1-piperazinyl)ethyl]-1-piperazineethanamine, bis(2-(piperazin-1-yl)ethyl)amine, 1-[2-[[2[[2-[(2-aminoethyl)amino]ethyl]amino]ethyl]amino]ethyl]piperazine, N-[2-[(2-aminoethyl)amino]ethyl]-1,4-piperazinediethanamine, N,N'-bis(2-aminoethyl)-1,4-piperazinediethanamine, N-[2-(1-piperazinyl)ethyl]-1,4-piperazinediethanamine, N-[2-[(2-aminoethyl)amino]ethyl]-1,4-piperazinediethanamine, N-[2-[(2-aminoethyl)amino]ethyl]-N'-[2-[4-(2-aminoethyl)-piperazin-1-yl]ethyl]ethane-1,2-diamine, 2-[4-[2-[2-[4-(2-aminoethyl)-piperazin-1-yl]ethylamino]ethyl]-piperazin-1-yl]ethylamine and the like.Among these, aminoethylpiperazine, piperazine-1,4-diethylamine, N-(2-aminoethyl)-N'-[2-(piperazin-1-yl)ethyl]ethane-1,2-diamine, N-[2-[4-(2-aminoethyl)piperazin-1-yl]ethyl]ethane-1,2-diamine, 4-[2-(1-piperazinyl)ethyl]-1-piperazineethanamine, bis(2-(piperazin-1-yl)ethyl)amine, 1-[2-[[2[[2-[(2-aminoethyl)amino]ethyl]amino]ethyl]amino]ethyl N-[2-[(2-aminoethyl)amino]ethyl]-1,4-piperazinediethanamine, N-[2-(1-piperazinyl)ethyl]-1,4-piperazinediethanamine are preferred, N-(2-aminoethyl)-N'-[2-(piperazin-1-yl)ethyl]ethane-1,2-diamine, N-[2-[4-(2-aminoethyl)piperazin-1-yl]ethyl]ethane-1,2-diamine, 4-[2-(1-piperazinyl)ethyl]-1-piperazineethanamine are more preferred, N-(2-aminoethyl)-N'-[2-(piperazin-1-yl)ethyl]ethane-1,2-diamine or N-[2-[4-(2-aminoethyl)piperazin-1-yl]ethyl]ethane-1,2-diamine are even more preferred.

[0018] In a preferred embodiment, the heavy metal treatment agent of the present invention includes an amine compound represented by formula (III). From the viewpoints of excellent treatment of Group 6 to 16 elements or compounds thereof in the periodic table, and additionally excellent stability of the dithiocarbamate in the heavy metal treatment agent and / or floc formation in wastewater treatment, it is preferable to include an amine compound represented by formula (III) having a structure combining cyclic and linear structures in one molecule, compared to amine compounds having only linear or cyclic structures in one molecule, or a mixture of amine compounds each consisting of only linear and cyclic structures. Among these, it is more preferable to include an amine compound represented by formula (III) having two or more cyclic structures in one molecule. The heavy metal treatment agent preferably includes, as the amine compound represented by formula (III), at least one selected from the amine compounds represented by formulas (IIIa), (IIIb), and (IIIc). In this case, the heavy metal treatment agent preferably contains, as the amine compound represented by formula (III), each of the amine compounds represented by formula (IIIa) and formula (IIIb). In this case, the heavy metal treatment agent preferably contains, as the amine compound represented by formula (III), an amine compound represented by formula (IIIc).

[0019] In a preferred embodiment, the heavy metal treatment agent of the present invention includes the amine compound represented by formula (I), formula (II), and formula (III). The amine compound represented by formula (I), formula (II), and formula (III) is particularly suitable for treating elements of groups 6 to 16 of the periodic table or compounds thereof, and is also suitable for at least one of increasing the stability of dithiocarbamate salts in the heavy metal treatment agent and forming flocs in wastewater treatment. The heavy metal treatment agent preferably includes, as the amine compound represented by any of formulas (I) to (III), the amine compound represented by formula (Ia), formula (IIa), formula (IIIa), and formula (IIIb). In this case, the heavy metal treatment agent preferably includes, as the amine compound represented by formula (III), the amine compound represented by formula (IIIc).

[0020] In the present invention, the amount ("%") of the amine compound refers to the area percentage of the peak area of ​​each amine compound relative to the total peak area excluding the peak of the solvent used in gas chromatographic analysis of the amine compound. When the amount of the amine compound is within the following range, the amine compound is suitable for treating elements of Groups 6 to 16 of the periodic table or compounds thereof, and is also suitable for at least one of increasing the stability of dithiocarbamate salts in heavy metal treatment agents and forming flocs in wastewater treatment. The amount of the amine compound represented by formula (I) is preferably 0.0% or more and 80.0% or less, more preferably 20.0% or more and 80.0% or less, even more preferably 20.0% or more and 55.0% or less, particularly preferably 25.0% or more and 55.0% or less, and even more preferably 40.0% or more and 55.0% or less. The amount of the amine compound represented by formula (II) is preferably 0.0% or more and 50.0% or less, more preferably 5.0% or more and 30.0% or less, even more preferably 5.0% or more and 25.0% or less, particularly preferably 15.0% or more and 25.0% or less, and particularly preferably 15.0% or more and 20.0% or less. The amount of the amine compound represented by formula (III) is preferably 10.0% or more and 100.0% or less, more preferably 10.0% or more and 80.0% or less, even more preferably 10.0% or more and 65.0% or less, particularly preferably 20.0% or more and 65.0% or less, particularly preferably 25.0% or more and 65.0% or less, even more preferably 27.0% or more and 65.0% or less, and most preferably 27.0% or more and 45.0% or less. The amount of the amine compound represented by formula (IIIa) is preferably 0.0% or more and 40.0% or less, more preferably 10.0% or more and 40.0% or less, even more preferably 10.0% or more and 35.0% or less, and particularly preferably 22.0% or more and 30.0% or less.The amount of the amine compound represented by formula (IIIb) is preferably 0.0% or more and 20.0% or less, more preferably 1.0% or more and 15.0% or less, even more preferably 1.0% or more and 10.0% or less, particularly preferably 6.0% or more and 10.0% or less, and particularly preferably more than 6.0% and 10.0% or less. The total amount of the amine compound of formula (IIIa) and the amine compound of formula (IIIb) is preferably 0.0% or more and 50.0% or less, more preferably 10.0% or more and 50.0% or less, even more preferably 13.0% or more and 40.0% or less, particularly preferably 17.0% or more and 40.0% or less, and particularly preferably 27.0% or more and 40% or less. The amount of the amine compound represented by formula (IIIc) is preferably 0.0% or more and 1.0% or less, more preferably 0.1% or more and less than 1.0%. The total amount of the amine compound of formula (IIIa), the amine compound of formula (IIIb), and the amine compound of formula (IIIc) is preferably 0.0% or more and 50.0% or less, more preferably 10.0% or more and 50.0% or less, even more preferably 13.0% or more and 40.0% or less, particularly preferably 17.0% or more and 40.0% or less, and even more preferably 28.0% or more and 40.0% or less.

[0021] The method for producing the amine compounds represented by the above formulas (I) to (III) is not particularly limited, and they may be produced by known methods, with inexpensive and simple methods being preferred.

[0022] In the agent for treating a heavy metal of the present invention, the dithiocarbamate is not particularly limited, but examples thereof include dithiocarbamate obtained by reacting an amine compound represented by any one of formulas (I) to (III), carbon disulfide, and a base such as a metal hydroxide.

[0023] The dithiocarbamic acid salt is not particularly limited, but examples thereof include alkali metal salts, alkaline earth metal salts, and ammonium salts of dithiocarbamic acid. Examples of alkali metal salts include lithium salts, sodium salts, and potassium salts. Examples of alkaline earth metal salts include magnesium salts and calcium salts. Among these, alkali metal salts are preferred, sodium salts and potassium salts are more preferred, and sodium salts are even more preferred.

[0024] In the heavy metal treatment agent of the present invention, the molar reaction ratio of the amine compound of the dithiocarbamate to a base such as carbon disulfide or a metal hydroxide is not particularly limited. Dithiocarbamate is a compound (salt-type functional group) in which a salt of a dithioic acid group is bonded to the nitrogen atom of an amine compound. Furthermore, an amine compound having two or more salts of dithiocarbamic acid groups incorporated into one molecule is preferred. Dithiocarbamate salts may be used alone or in combination of two or more. Considering the need to enhance heavy metal treatment performance in incineration ash treatment, wastewater treatment, and other processes, carbon disulfide is preferably reacted in a ratio of 0.5 to 1 molar ratio, more preferably 0.7 to 1 molar ratio, even more preferably 0.8 to 1 molar ratio, and particularly preferably 0.9 to 1 molar ratio, relative to the nitrogen atoms of the primary and secondary amino groups calculated from the amount of amine compound obtained by the above method.

[0025] The method for producing a dithiocarbamate by reacting an amine compound, carbon disulfide, and a base is not particularly limited, but can be introduced, for example, by dissolving or suspending an amine compound and a base such as a metal hydroxide exemplified above in a solvent such as water, and then adding carbon disulfide to cause reaction. If necessary, unreacted carbon disulfide is finally removed. If by-products other than dithiocarbamate are produced in the production of a dithiocarbamate, gases such as carbon disulfide may be generated from the by-products during storage or use of the heavy metal treatment agent. To suppress the generation of such gases, an excess of amine compound may be used during the production of the heavy metal treatment agent to contain unreacted amine compound, or at least one selected from an amine compound and an amine derivative may be added after the production of the dithiocarbamate.

[0026] The formulation of the heavy metal treatment agent of the present invention is not particularly limited as long as it contains a dithiocarbamate, and may be, for example, a solid, liquid, or viscous substance, although from the viewpoint of handling, it is preferably used in the form of a liquid aqueous solution. When the heavy metal treatment agent is used as an aqueous solution, the content of the dithiocarbamate is not particularly limited, but from the viewpoint of the stability of the dithiocarbamate, it is preferably 20% by mass to 60% by mass, and more preferably 30% by mass to 50% by mass, based on the total amount of the heavy metal treatment agent. In terms of the stability of the aqueous solution of the heavy metal treatment agent during storage, it is preferable to include an amine compound, as this inhibits crystal formation.

[0027] The heavy metal treatment agent of the present invention may contain other components within the range that does not impair the effects of the present invention. Examples of other components include, but are not limited to, amine compounds, amine derivatives, ammonium salts, organic solvents, reducing agents, oxidizing agents, alkali metal hydroxides, pH adjusters, inorganic heavy metal treatment agents, flocculants, rust inhibitors, scale inhibitors, antifoaming agents, stabilizers, gas suppressants, surfactants, etc.

[0028] Next, we will explain heavy metal treatment using the heavy metal treatment agent of the present invention. When mixed with solid objects, liquid objects, or waste gases, including slurries containing the following Group 6 to 16 elements or compounds thereof, the heavy metal treatment agent of the present invention reacts with the elements or compounds thereof to form insoluble substances in water, thereby reducing or preventing elution from the solid objects, or separating the insoluble substances from the liquid objects to remove the Group 6 to 16 elements or compounds thereof. Examples of solid objects include, but are not limited to, incineration ash (fly ash and bottom ash), slag, sludge, soil, shredder dust, and the like generated at waste incineration plants. Examples of liquid objects include, but are not limited to, wastewater, waste oil, liquid sludge, and waste gas cleaning waste liquid.

[0029] The heavy metal treatment agent of the present invention targets elements or compounds of Groups 6 to 16 of the periodic table. Examples of Group 6 elements include chromium, molybdenum, tungsten, and seaborgium. Examples of Group 7 elements include manganese, technetium, rhenium, and bohrium. Examples of Group 8 elements include iron, ruthenium, osmium, and hassium. Examples of Group 9 elements include cobalt, rhodium, iridium, and meitnerium. Examples of Group 10 elements include nickel, palladium, platinum, and darmstadtium. Examples of Group 11 elements include copper, silver, gold, and roentgenium. Examples of Group 12 elements include zinc, cadmium, mercury, and copernicium. Examples of Group 13 elements include boron, aluminum, gallium, indium, thallium, and nihonium. Examples of Group 14 elements include carbon, silicon, germanium, tin, lead, and flerovium. Examples of Group 15 elements include nitrogen, phosphorus, arsenic, antimony, bismuth, and moscovium. Examples of Group 16 elements include oxygen, sulfur, selenium, tellurium, polonium, and livermorium. Elements in the same group have the same electronic state in their outermost shells, and therefore can be treated in the same manner using the heavy metal treatment agent of the present invention. Among the above elements, particularly, examples of Group 6 elements include chromium, molybdenum, and tungsten; examples of Group 7 elements include manganese; examples of Group 8 elements include iron, ruthenium, and osmium; examples of Group 9 elements include cobalt, rhodium, and iridium; examples of Group 10 elements include nickel, palladium, and platinum; examples of Group 11 elements include copper, silver, and gold; examples of Group 12 elements include zinc, cadmium, and mercury; examples of Group 13 elements include boron, gallium, indium, and thallium; examples of Group 14 elements include germanium, tin, and lead; examples of Group 15 elements include arsenic, antimony, and bismuth; and examples of Group 16 elements include selenium and tellurium. Among these, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, aluminum, tin, lead, arsenic, selenium, or compounds thereof can be suitably treated, and further, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, aluminum, lead, arsenic, selenium, or compounds thereof can be suitably treated.For example, among these, chromium, manganese, iron, nickel, copper, zinc, cadmium, mercury, lead, arsenic, selenium, or compounds thereof, for which landfill standards or wastewater standards are established, can be more suitably treated. Examples of compounds of the above elements include substances in which the above elements are bonded to other elements via covalent bonds, ionic bonds, coordinate bonds, etc., and include, but are not limited to, oxides, hydroxides, oxoacids and their salts, halides, complexes, complex salts, etc.

[0030] (Incineration Ash Treatment) The treatment of incineration ash using the heavy metal treatment agent of the present invention is not particularly limited, and may be, for example, incineration ash (fly ash and bottom ash) generated in combustion facilities such as combustion furnaces and melting furnaces for municipal waste, industrial waste, sludge, biomass boilers, paper sludge, coal, refuse-derived fuel (RDF: Refuse Derived Fuel or RPF: Refuse Derived Paper and Plastics Densified Fuel), etc., or incineration ash (fly ash and bottom ash) generated in combustion facilities such as electric furnaces for iron and steel making, roasting furnaces for metal refining, sintering furnaces, calciners, blast furnaces, converters, melting furnaces, and drying furnaces. In addition to incineration ash, the treatment of soil, sludge, slag, etc. containing elements of Groups 6 to 16 of the periodic table or compounds thereof is also targeted.

[0031] Here, "incinerator ash" refers to bottom ash, which is the cinders from an incinerator, and fly ash, which floats with the gas components produced by incineration. Fly ash also includes fly ash generated by melting treatment (molten fly ash). Fly ash may also contain other types of flue gas treatment chemicals, such as slaked lime and activated carbon. In the present invention, no particular distinction is made between these. Hereinafter, when referring to incinerator ash, bottom ash and fly ash are used without distinction.

[0032] The amount of the heavy metal treatment agent of the present invention used is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, as an addition rate relative to the incineration ash. Also, it is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. A usage amount within this range is suitable for achieving the effects of the present invention. If an excessive amount of the heavy metal treatment agent is used, there is a risk that the heavy metals insolubilized by the dithiocarbamate will be re-eluted.

[0033] The heavy metal treatment agent of the present invention can suitably treat incineration ash containing at least any one of elements or compounds of Groups 6, 12, and 14 among the elements or compounds of Groups 6 to 16 listed above.

[0034] In terms of the reaction efficiency between heavy metals and the dithiocarbamate contained in the heavy metal treatment agent of the present invention, if the treated ash is in a dry powder form, the heavy metal ions and the dithiocarbamate cannot move smoothly, reducing the frequency of contact and preventing the reaction from proceeding sufficiently. If the treated ash is in a liquid form, a dehydration step is required, or the proportion of water in the transport of the treated ash increases, making it uneconomical. Therefore, to properly treat heavy metals, it is desirable to add an optimal amount of water to form the treated ash in a powder, lump, or slurry form with an appropriate moisture content, with lump being more desirable. The water addition rate is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, relative to the incineration ash. Furthermore, the water addition rate relative to the incineration ash is preferably 150% by mass or less, preferably 100% by mass or less, more preferably 80% by mass or less, even more preferably 60% by mass or less, and particularly preferably 40% by mass or less. By adding more than a specific amount of water, the dithiocarbamate can efficiently come into contact with the heavy metals in the incineration ash, promoting the formation of insoluble matter. If the water addition rate is too high, the treated ash will not form a mass but will instead become a slurry or liquid, making handling, such as transporting the treated ash, more difficult.

[0035] When the heavy metal treating agent and water of the present invention are mixed with incineration ash, they may be added to the incineration ash simultaneously or separately. Alternatively, the heavy metal treating agent and water may be mixed in advance and then added to the incineration ash. The procedure for adding and mixing the heavy metal treating agent, water, and incineration ash is optional.

[0036] The heavy metal treatment agent of the present invention can treat any of basic, acidic, and neutral incineration ash, and is particularly suitable for treating basic and neutral incineration ash, with basic incineration ash being more suitable. The pH of the eluate from the incineration ash can be used as an indicator of the basicity or acidity of incineration ash. From this perspective, the heavy metal treatment agent of the present invention can treat incineration ash from which the pH of the eluate (sample solution) measured by the test method of Environmental Agency Notification No. 13 is preferably 6 or higher, more preferably 9 or higher, even more preferably 11.5 or higher, and particularly preferably 12 or higher. In treating incineration ash, a basic or acidic compound, a pH adjuster, or the like may be added to the incineration ash to adjust the pH of the eluate.

[0037] In the treatment of incineration ash using the heavy metal treatment agent of the present invention, other components can be used together with the heavy metal treatment agent and water, as long as the effects of the agent are not impaired. Such other components are not particularly limited, but include, for example, coagulants, pH adjusters, rust inhibitors, reducing agents, oxidizing agents, surfactants, adsorbents, alkali metal hydroxides, cement, water glass, etc.

[0038] When incineration ash is treated with a heavy metal treating agent, for example, it may be mixed with water or the like and then post-treated. The post-treatment is carried out by standing or stirring, thereby stably suppressing the elution of heavy metals. In a waste incineration facility, fly ash generated by incineration in an incinerator is transferred and collected together with exhaust gas to a bulkhead bag filter, a flow-through electrostatic precipitator, a cyclone, or the like. The collected fly ash is stored, for example, in a silo and then transferred to a batch or continuous mixer, where a heavy metal treating agent and water are added and the mixture is uniformly mixed. The mixture discharged from the mixer is transported by a conveyor and sent to a pit. The post-treatment of the mixture can be carried out in indoor facilities such as conveyors or pits, or in containers or other storage areas where the mixture discharged from the mixer is transported and stored indoors.

[0039] Bottom ash (burnt remains) generated by incineration in an incinerator is usually cooled in a water tank because it is hot when removed from the incinerator. Methods include adding the heavy metal treatment agent of the present invention to the water tank and allowing it to react in the water tank to make it insolubilizable, or adding the heavy metal treatment agent and water to the cooled and dehydrated bottom ash as is or after pulverization, followed by stirring and mixing to make it insolubilizable. The post-treatment of the insolubilized bottom ash can be carried out in indoor facilities such as conveyors and pits, or in containers, which are transported and stored indoors, just like fly ash.

[0040] (Wastewater treatment) Wastewater treatment using the heavy metal treatment agent of the present invention refers to a treatment for separating a target element of Groups 6 to 16 of the periodic table or a compound thereof from water to be treated, and includes, but is not limited to, a treatment for separating insoluble flocs (aggregates or precipitates) produced when the heavy metal treatment agent reacts with the target element or a compound thereof. The heavy metal treatment agent of the present invention has excellent floc-forming ability, which facilitates floc removal and allows the target element or a compound thereof to be suitably treated.

[0041] Wastewater treatment using a heavy metal treatment agent can be carried out by adding the heavy metal treatment agent to water to be treated. The water to be treated refers to water containing the element or compound thereof to be treated, and includes water before and after the addition of the heavy metal treatment agent. Water to be treated can be suitably treated even if it contains elements or compounds thereof other than the target elements. Furthermore, water to be treated can be suitably treated even if it contains, but is not limited to, complexing agents such as EDTA, organic acids such as citric acid, phosphoric acid compounds, amine compounds, and cyanide compounds, oxidizing agents, reducing agents, surfactants, salts, organic compounds, inorganic compounds, and the like.

[0042] The treatment conditions after the addition are not particularly limited, but can be, for example, by stirring and leaving to stand. After the treatment, insoluble matter and solid matter may be removed by separation. The method for removing insoluble matter and solid matter is not particularly limited, and examples thereof include filtration, centrifugation, and a method in which solid matter is allowed to settle and then separated from the supernatant.

[0043] The stirring is not particularly limited to the apparatus and operation, and conventionally known apparatus and operation can be used. The standing does not require the use of a special apparatus, and solid-liquid separation can be performed, for example, by providing a sedimentation tank or the like.

[0044] In treatment using the heavy metal treatment agent of the present invention, other components, such as a pH adjuster, a flocculant, an alkali metal hydroxide, an inorganic heavy metal treatment agent, a rust inhibitor, a scale inhibitor, an antifoaming agent, an adsorbent, a surfactant, a complexing agent, a chelating agent, an oxidizing agent, a reducing agent, etc., may be added to the water to be treated together with the heavy metal treatment agent. By adding a pH adjuster and treating within an appropriate pH range, decomposition of the heavy metal treatment agent is prevented, floc formation is promoted, and the elements of Groups 6 to 16 of the periodic table or compounds thereof can be properly treated.

[0045] The pH adjuster is not particularly limited, but examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and inorganic alkalis such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. In addition, the flocculants listed below may also be used as the pH adjuster.

[0046] The addition of a heavy metal treatment agent and a flocculant improves the settling properties of the flocs. If necessary, a flocculant is added and stirred to separate the resulting flocs. This removes the target element or its compound contained in the wastewater. The flocculant is not particularly limited, but examples include polymer flocculants, inorganic flocculants, and minerals. Among these, polymer flocculants and inorganic flocculants are preferred, and polymer flocculants are more preferred.

[0047] The polymer flocculant may be anionic, cationic, nonionic, or amphoteric, and is not particularly limited. Examples include anionic polymer flocculants such as polyacrylamide, sodium polyacrylate, polyacrylic acid, and natural polymers; cationic polymers such as polymethacrylate, polyacrylate, polyamine, polydadomac, and dicyandiamide; nonionic polymers such as polyacrylamide, polyethylene glycol, and polyvinyl alcohol; and amphoteric polymers such as polyacrylate-acrylic acid copolymers. Specific examples include sodium polyacrylate, sodium alginate, copolymers of acrylamide and sodium acrylate, copolymers of acrylamide and sodium acrylamido-2-methylpropanesulfonate (AMPS), copolymers of acrylamide-acrylic acid-AMPS, polydimethylaminoethyl (meth)acrylate quaternary salt, copolymers of dimethylaminoethyl (meth)acrylate quaternary salt and acrylamide, polydimethyldiallylammonium chloride, copolymers of dimethyldiallylammonium chloride and acrylamide, polyamidine, epichlorohydrin-dimethylamine condensates, dicyandiamide-ammonium chloride-formaldehyde polycondensates, polyacrylamide, polyethylene oxide, copolymers of dimethylaminoethyl (meth)acrylate quaternary salt and acrylic acid, Hoffmann degradation products of polyacrylamide, etc. Among these, anionic and cationic surfactants are preferred, and anionic surfactants are more preferred. Among the anionic types, sodium polyacrylate and copolymers of acrylamide and sodium acrylate are preferred, and among the cationic types, copolymers of dimethyldiallylammonium chloride and acrylamide are preferred.

[0048] The inorganic flocculant is not particularly limited, but examples thereof include iron-based inorganic flocculants (ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate, polyferric sulfate, etc.), aluminum-based inorganic flocculants (aluminum sulfate, polyaluminum chloride, aluminum chloride, etc.), and alkaline-based inorganic flocculants (calcium chloride, magnesium hydroxide, potassium aluminate, etc.). Among these, iron-based inorganic flocculants and aluminum-based inorganic flocculants are preferred, with ferric chloride, ferrous sulfate, polyferric sulfate, aluminium sulfate, polyaluminum chloride, and calcium chloride being more preferred, and ferric chloride, ferrous sulfate, polyferric sulfate, aluminium sulfate, and polyaluminum chloride being even more preferred. The above flocculants may be used alone or in combination of two or more.

[0049] The mineral is not particularly limited, but examples thereof include carbonate minerals such as hydrotalcite, magnesite, and limestone; silicate minerals such as zeolite, montmorillonite, kaolin, bentonite, and silica; oxide minerals such as alumina; sulfate minerals such as gypsum; and phosphate minerals such as hydroxyapatite.

[0050] The flocculant may be used alone or in combination with two or more types, and may be used once or twice or more times. The combined use of an inorganic flocculant and a polymer flocculant is also a preferred embodiment. By using a polymer flocculant and an inorganic flocculant in combination, elements 6, 10, 11, 12, 14, 15, and 16 or compounds thereof, among the elements or compounds of Groups 6 to 16 listed above, can be suitably treated.

[0051] Although the present invention has been described above based on the embodiment, the present invention is not limited to this embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0052] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Amine Compound] As the amine compound, commercially available products and reagents that are commonly available were used. Carbon disulfide, sodium hydroxide, and potassium hydroxide were used from Kanto Chemical Co., Inc. The amount of the amine compound was analyzed by gas chromatography (GC) of a sample prepared by dissolving the amine compound in a solvent (methanol). A GC-2010Plus (Shimadzu Corporation) was used for the GC, and a capillary column TC-1 (length 15 m, inner diameter 0.25 mm, liquid phase film thickness 0.25 μm) (GL Sciences Inc.) was used as the column, and measurements were performed under the following conditions.

[0053] SPL (vaporization chamber) Temperature: 300°C Total flow rate: 45.1 mL / min Pressure: 48.9 kPa Column flow rate: 1.03 mL / min Carrier gas: Helium Linear velocity: 30.2 cm / sec Split ratio: 40.0 Purge flow rate: 3.0 mL / min Temperature rise conditions Set temperature: 50°C, Hold time: 3 min Heating rate: 10.0°C / min, Set temperature: 160°C Heating rate: 20.0°C / min, Set temperature: 300°C, Hold time: 10 min FID (detector) Temperature: 300°C Makeup gas: Helium Makeup flow rate: 30.0 mL / min H2 flow rate: 40.0 mL / min Air flow rate: 400.0 mL / min.

[0054] The amount ("%") of each amine compound indicates the area proportion (area percentage) of each amine compound in the total peak area in the GC chart excluding the peak of the solvent used in the analysis. The tetraethylenepentamine below was a commercially available product (a mixture of linear, branched, and cyclic and linear) that is a commonly distributed industrial product. The above analysis of this tetraethylenepentamine revealed that it consisted of 48.2% linear amine compounds of formula (Ia), 18.3% branched amine compounds of formula (IIa), and 32.7% amine compounds of formula (III), which are a combination of cyclic and linear amine compounds (of which formula (IIIa): 25.5%, formula (IIIb): 6.4%, and formula (IIIc): 0.8%).

[0055] [Heavy Metal Treatment Agent] Heavy Metal Treatment Agent A A sample (40.0 mass% aqueous solution) was used, prepared by reacting 15.9 g of N-(2-aminoethyl)piperazine (manufactured by Tokyo Chemical Industry Co., Ltd.), 18.7 g of carbon disulfide, and 20.5 g of 48.0% aqueous sodium hydroxide solution in 44.9 g of ion-exchanged water (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and secondary amino group of the amine compound). N-(2-aminoethyl)piperazine was 100.0% of the amine compound of formula (III), which is a combination of cyclic and linear chains.

[0056] Heavy metal treatment agent B A sample (40.0 mass% aqueous solution) prepared by reacting 13.0 g of tetraethylenepentamine (commercially available product: a mixture of linear, branched, and cyclic / linear combinations), 20.9 g of carbon disulfide, and 22.9 g of a 48.0% aqueous sodium hydroxide solution in 43.2 g of ion-exchanged water was used (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and secondary amino group calculated from the amount of the amine compound obtained by the above method).

[0057] Heavy metal treatment agent C: A sample (40.0 mass% aqueous solution) was prepared by reacting 5.3 g of N-(2-aminoethyl)piperazine (manufactured by Tokyo Chemical Industry Co., Ltd.), 8.7 g of tetraethylenepentamine (commercially available product: a mixture of linear, branched, and cyclic / linear combinations), 20.2 g of carbon disulfide, and 22.1 g of a 48.0% aqueous sodium hydroxide solution in 43.7 g of ion-exchanged water (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and secondary amino group calculated from the amount of the amine compound obtained by the above method). The amount of the amine compounds was 32.1% for the linear amine compound of formula (Ia), 12.2% for the branched amine compound of formula (IIa), and 55.2% for the amine compound of formula (III), which is a combination of cyclic and linear compounds (of which, formula (IIIa) was 17.0%, formula (IIIb) was 4.3%, formula (IIIc) was 0.6%, and N-(2-aminoethyl)piperazine was 33.3%).

[0058] Heavy metal treatment agent D A sample (40.0 mass% aqueous solution) prepared by reacting 2.2 g of triethylenetetramine (manufactured by Sigma-Aldrich Japan LLC), 10.4 g of tetraethylenepentamine (commercially available product: a mixture of linear, branched, and cyclic / linear tetraethylenepentamine), 21.2 g of carbon disulfide, and 23.4 g of a 48.0% aqueous sodium hydroxide solution in 42.8 g of ion-exchanged water was used (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and secondary amino group calculated from the amount of the amine compound obtained by the above method). The amount of the amine compounds was 58.6% for the linear amine compound of formula (I) (of which 38.6% was formula (Ia) and 20.0% was triethylenetetramine), 14.6% for the branched amine compound of formula (IIa), and 26.2% for the amine compound of formula (III) which is a combination of cyclic and linear compounds (of which 20.4% was formula (IIIa), 5.1% was formula (IIIb), and 0.7% was formula (IIIc)).

[0059] Heavy metal treatment agent E A sample (40.0 mass% aqueous solution) was used, prepared by reacting 9.4 g of ethylenediamine (manufactured by Kanto Chemical Co., Inc.), 23.7 g of carbon disulfide, and 26.0 g of a 48.0% aqueous sodium hydroxide solution in 40.8 g of ion-exchanged water (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and the secondary amino group of the amine compound).

[0060] Heavy metal treatment agent F A sample (40.0 mass% aqueous solution) prepared by reacting 10.4 g of diethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 23.0 g of carbon disulfide, and 25.2 g of a 48.0% aqueous sodium hydroxide solution in 41.4 g of ion-exchanged water was used (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and the secondary amino group of the amine compound).

[0061] Heavy metal treatment agent G A sample (40.0 mass% aqueous solution) was used, prepared by reacting 11.0 g of anhydrous piperazine (manufactured by Tokyo Chemical Industry Co., Ltd.), 19.4 g of carbon disulfide, and 30.5 g of a 48.0% aqueous potassium hydroxide solution in 39.1 g of ion-exchanged water (the amount of carbon disulfide was 1 mole per nitrogen atom of the primary amino group and the secondary amino group of the amine compound).

[0062] Heavy metal treatment agent H A sample (40.0 mass % aqueous solution) prepared by mixing heavy metal treatment agent F (35.0 g) and heavy metal treatment agent G (15.0 g) was used (carbon disulfide was used in an amount of 1 mole per nitrogen atom of the primary amino group and the secondary amino group of the amine compound).

[0063] (Incineration Ash Treatment) Using a porcelain mortar as a container, 100 g of incineration ash (fly ash captured by a bag filter) generated at a municipal waste incineration plant was added with a heavy metal treatment agent and water at the addition rates shown in Table 1 so that the dithiocarbamate group content in the added heavy metal treatment agent was the same as that of the incineration ash, and the mixture was kneaded for 10 minutes to achieve uniform mixing. As a blank test, treatment was carried out in the same manner as in the Examples, except that only water was added. In all of the Examples, Comparative Examples, and Blank Tests, the incineration ash (treated ash) after treatment was in a lump form and had been properly treated. The elution concentrations of chromium, mercury, and lead from the resulting treated ash were measured in accordance with the test method of Environment Agency Notification No. 13. The results are shown in Table 1. The concentrations of chromium (Group 6) and lead (Group 14) in the eluate were measured using an ICP optical emission spectrometer (ICPE-9820, Shimadzu Corporation), and the concentration of mercury (Group 12) was measured using a mercury analyzer (MA-3000, Nippon Instruments Co., Ltd.). The pH of the eluate was measured using a pH meter (F-72, Horiba Ltd.) and a pH electrode (9632-10D, Horiba Ltd.).

[0064]

[0065] As can be seen from Table 1, when the heavy metal treatment agent was added so that the dithiocarbamate group content in the added heavy metal treatment agent was the same, the elution concentrations of chromium (Group 6), mercury (Group 12), and lead (Group 14) were lower in Examples 1 to 4 than in Comparative Examples 1 to 4, and the heavy metal treatment agent of the present invention had high treatment performance for elements of Groups 6, 12, and 14, and the dithiocarbamate of an amine compound containing any of Formula (I), Formula (II), or Formula (III), or the dithiocarbamate of an amine compound containing Formula (III), was excellent in performance for treating elements of Groups 6, 12, and 14 or compounds thereof.

[0066] Furthermore, it was suggested that the dithiocarbamate of an amine compound having formula (III) with a structure combining a cyclic and a linear structure in one molecule in Examples 1 to 4 has excellent performance in treating elements of Groups 6, 12, and 14 or compounds thereof, compared with Comparative Examples 1 and 2 which are dithiocarbamate of an amine compound having only a linear structure in one molecule, Comparative Example 3 which is a dithiocarbamate of an amine compound having only a cyclic structure, and Comparative Example 4 which is a mixture of dithiocarbamate of an amine compound having only a linear structure and a cyclic structure.

[0067] In a comparison between Example 1 and Examples 2 to 4, the elution concentrations of chromium, mercury, and lead were smaller in Examples 2 to 4, and it was confirmed that a dithiocarbamate of an amine compound containing any of the amine compounds of formula (IIIa), formula (IIIb), and formula (IIIc), particularly containing formula (IIIa), formula (IIIb), and further formula (IIIc), or a dithiocarbamate of an amine compound containing an amine compound of formula (I), formula (II), and formula (III), particularly containing formula (Ia), formula (IIa), formula (IIIa), formula (IIIb), and further formula (IIIc), has excellent performance in treating elements of Group 6, Group 12, and Group 14 or compounds thereof.

[0068] Furthermore, in a comparison of Comparative Examples 1 and 2 with Comparative Example 3, the treatment performance for lead was superior in Comparative Example 3, confirming that dithiocarbamates of amine compounds having only cyclic structures are superior to dithiocarbamates of amine compounds having only linear structures in the treatment performance for Group 14 elements or compounds thereof. These findings suggest that even among amine compounds having formula (III) with a structure combining cyclic and linear structures, dithiocarbamates of amine compounds having formula (IIIc) with two cyclic structures are superior in the treatment performance for elements of Groups 6, 12, and 14 or compounds thereof.

[0069] Comparing Examples 2 and 3 with Example 4, Examples 2 and 3 showed a lower lead elution concentration, and the performance for treating Group 14 elements or compounds thereof tended to be better as the amount of the amine compound of formula (III) in the mixed system of formulas (I) to (III) increased.

[0070] Furthermore, a comparison of Example 2 with Examples 3 and 4 showed that Example 2 had a lower mercury elution concentration, suggesting that the greater the total amount of the amine compounds of formula (IIIa) and formula (IIIb), the better the performance in treating the target element or its compounds. It also suggested that the greater the amount of the amine compound of formula (IIIc), the better the overall performance in treating the target element or its compounds in the treatment of chromium, mercury, and lead. It was also confirmed that the incineration ash treated in Examples 1 to 4 contained cadmium (Group 12), arsenic (Group 15), and selenium (Group 16) below the landfill standards. Furthermore, the pH of the eluates from the untreated incineration ash, Examples, Comparative Examples, and Blank Tests was all 12.4, suggesting that when the pH of the incineration ash treatment solution is 11.5 or higher, the heavy metal treatment agent of the present invention can treat incineration ash containing elements of Groups 6 to 16 or their compounds.

[0071] From the above, it is suggested that the agent for treating heavy metals of the present invention has excellent performance in treating elements of Groups 6 to 16 or compounds thereof.

[0072] (Wastewater Treatment Test) The following reagents were used to prepare the test solution to be treated: Aqueous hydrochloric acid solution or aqueous sodium hydroxide solution was used to adjust the pH during preparation of the test solution. Chromium(III) chloride hexahydrate (Kanto Chemical Co., Ltd.) Cobalt(II) chloride hexahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) Iron(III) chloride hexahydrate (Kanto Chemical Co., Ltd.) Copper(II) chloride dihydrate (Kokusan Chemical Co., Ltd.) Zinc(II) chloride (Kokusan Chemical Co., Ltd.) Aluminum sulfate 14-18 hydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) Cadmium(II) chloride (Fujifilm Wako Pure Chemical Industries, Ltd.) Lead(II) chloride (Kanto Chemical Co., Ltd.) Mercury(II) chloride (Kanto Chemical Co., Ltd.) Arsenic(III) oxide (Kanto Chemical Co., Ltd.) Sodium selenite (Fujifilm Wako Pure Chemical Industries, Ltd.) Potassium dichromate (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0073] The following flocculants were used: Aluminium sulfate aqueous solution (manufactured by Taimei Chemical Industry Co., Ltd.), 38% ferric chloride aqueous solution (manufactured by Hayashi Pure Chemical Industries Co., Ltd.), and polymer flocculant (anionic polymer flocculant: Miyofloc AP-800 (manufactured by Miyoshi Oil & Fats Co., Ltd.)).

[0074] [Treatment of Copper-Containing Wastewater] An aqueous solution containing 50 mg / L of copper (Group 11) was prepared as test wastewater (water to be treated), and the wastewater was treated and evaluated according to the following procedure.

[0075] While stirring 200 mL of the test wastewater at 200 rpm, the heavy metal treatment agent shown in Table 2 was added in an amount such that the dithiocarbamate group content in the heavy metal treatment agent added was the same as that of the wastewater, and the mixture was stirred for 10 minutes. After stirring was completed, the mixture was left to stand for 10 minutes, and the entire amount of flocs was filtered using a glass filter paper (GA-100, manufactured by Advantec Toyo Co., Ltd.) whose weight had been measured in advance, and the copper concentration of the filtrate was measured. The copper concentration in the filtrate (treated water) was measured using an ICP atomic emission spectrometer. The filtered flocs were dried together with the glass filter paper at 105°C for 2 hours, and then weighed, and the dry weight of the flocs was calculated from the weight difference. The results are shown in Table 2.

[0076]

[0077] As can be seen from Table 2, when the heavy metal treatment agent was added so that the dithiocarbamate group content in the added heavy metal treatment agent was the same, the copper (Group 11) concentration in the filtrate was lower in Examples 5 to 8 compared to Comparative Examples 5 to 8, confirming that the heavy metal treatment agent of the present invention has high treatment performance for Group 11 elements. The dithiocarbamate salts of the amine compound containing any of Formula (I), Formula (II), and Formula (III), and the dithiocarbamate salts of the amine compound containing Formula (III), had excellent performance in treating Group 11 elements or compounds thereof.

[0078] Furthermore, as in the case of the treatment of incineration ash, it was suggested that the dithiocarbamate of an amine compound containing formula (III), which has a structure combining cyclic and linear structures in one molecule, of Examples 5 to 8 has superior performance in treating Group 11 elements or compounds thereof, compared to Comparative Examples 5 and 6, which are dithiocarbamate of an amine compound having only a linear structure in one molecule, Comparative Example 7, which is a dithiocarbamate of an amine compound having only a cyclic structure, and Comparative Example 8, which is a mixture of dithiocarbamate of an amine compound having only a linear structure and a cyclic structure.

[0079] When Example 5 is compared with Examples 6 to 8, the copper concentration in the filtrate is lower in Examples 6 to 8, and it has been confirmed that dithiocarbamic acid salts of amine compounds containing any of the amine compounds of formula (IIIa), formula (IIIb), and formula (IIIc), particularly those containing formula (IIIa), formula (IIIb), and formula (IIIc), and dithiocarbamic acid salts of amine compounds containing the amine compounds of formula (I), formula (II), and formula (III), particularly those containing formula (Ia), formula (IIa), formula (IIIa), formula (IIIb), and formula (IIIc), are excellent in performance for treating Group 11 elements or compounds thereof.

[0080] In a comparison between Examples 6 and 7 and Example 8, the copper concentrations in the filtrates of Examples 6 and 7 were lower, and the performance for treating Group 11 elements or compounds thereof tended to be better as the amount of the amine compound of formula (III) in the mixed system of formulas (I) to (III) increased.

[0081] Furthermore, in a comparison of Example 6 with Examples 7 and 8, the copper concentration in the filtrate was lower in Example 6, suggesting that the larger the total amount of the amine compounds of formula (IIIa) and formula (IIIb), the better the performance in treating the target element or its compound.

[0082] Regarding the floc-forming ability, the dry weight of the flocs in Examples 5 to 8 was 40 mg or more, whereas the dry weight of the flocs in Comparative Examples 5 to 8 was less than 40 mg.

[0083] It has been confirmed that a dithiocarbamate of an amine compound containing any one of formula (I), formula (II), and formula (III), or a dithiocarbamate of an amine compound containing formula (III), has an excellent ability to form flocs with a target element or a compound thereof.

[0084] [Test for Treatment of Various Elements] Test wastewater containing each element shown in Table 3 was prepared as test wastewater (water to be treated). To 200 mL of this test wastewater, heavy metal treatment agent B was added in the amount shown in Table 3 while stirring at 200 rpm, and the mixture was stirred for 10 minutes. Next, the pH was adjusted to 8 using an aqueous sodium hydroxide solution. After that, a polymer flocculant was added and the mixture was stirred for 2 minutes at 20 rpm. After stirring, the mixture was left to stand for 10 minutes, and flocs were filtered off using filter paper (JIS P3801 Type 5A). The concentrations of each element in the test wastewater and the filtrate were measured using an ICP atomic emission spectrometer. The results are shown in Table 3.

[0085]

[0086] As can be seen from Table 3, the concentrations of each element in wastewater were reduced by treatment with the heavy metal treatment agent of the present invention, and it was therefore confirmed that wastewater containing elements of Groups 6 to 13 can be suitably treated by using the heavy metal treatment agent of the present invention.

[0087] [Treatment of Wastewater Containing Nickel and Zinc] Test wastewater containing nickel (Group 10) at a concentration of 10 mg / L and zinc (Group 12) at a concentration of 10 mg / L was prepared in advance.

[0088] In Example 14 and Comparative Examples 9 and 10, 200 mL of the test wastewater was stirred at 200 rpm. The heavy metal treatment agent shown in Table 4 was added in the amount shown in Table 4 so that the dithiocarbamate group content in the heavy metal treatment agent was the same as that of the wastewater, and the mixture was stirred for 10 minutes. The pH was then adjusted to 8 using aqueous sodium hydroxide. A polymer flocculant was then added and the mixture was stirred at 20 rpm for 2 minutes. After stirring, the mixture was left to stand for 10 minutes, and the flocs were filtered off with filter paper. The nickel and zinc concentrations in the filtrate were measured. The nickel and zinc concentrations in the filtrate were measured using an ICP atomic emission spectrometer. In Example 15, the same procedure as above was performed, except that after the heavy metal treatment agent was added and stirred, an aqueous aluminum sulfate solution was added as an inorganic flocculant in the amount shown in Table 4, followed by stirring for 5 minutes. The results are shown in Table 4.

[0089]

[0090] As can be seen from Table 4, Example 14 had lower concentrations of nickel and zinc in the filtrate compared to Comparative Examples 9 and 10, and the heavy metal treatment agent of the present invention had high treatment performance for Group 10 and Group 12 elements or compounds thereof. Example 15, in which an inorganic flocculant was used, had an even lower zinc concentration after treatment, confirming that the combined use of the heavy metal treatment agent of the present invention with a polymer flocculant and an inorganic flocculant improves the treatment effect of the heavy metal treatment agent of the present invention on Group 10 and Group 12 elements or compounds thereof.

[0091] It is also suggested that treatment using the heavy metal treatment agent of the present invention in the above system is applicable to plating factory wastewater.

[0092] [Treatment of wastewater containing complex elements 1] Test wastewater containing 0.5 mg / L of chromium (Group 6), 0.5 mg / L of copper (Group 11), 0.2 mg / L of cadmium (Group 12), 1.0 mg / L of mercury (Group 12), 1.5 mg / L of lead (Group 14), and 50 g / L of sodium chloride was prepared in advance.

[0093] While stirring 200 mL of the test wastewater at 200 rpm, the heavy metal treatment agent shown in Table 5 was added in an amount such that the dithiocarbamate group content in the heavy metal treatment agent was the same as that of the wastewater, and the mixture was stirred for 10 minutes. Subsequently, a 38% aqueous solution of ferric chloride was added as an inorganic flocculant in the amount shown in Table 5, and the mixture was stirred for 5 minutes. The pH was then adjusted to 8 using an aqueous sodium hydroxide solution. A polymer flocculant was then added, and the mixture was stirred for 2 minutes at 20 rpm. After stirring, the mixture was left to stand for 10 minutes, and the flocs were filtered off with filter paper. The element concentrations of each element in the filtrate were measured. The chromium, copper, cadmium, and lead concentrations in the filtrate were measured using an ICP atomic emission spectrometer, and the mercury concentration was measured using a mercury analyzer. The results are shown in Table 5.

[0094]

[0095] As can be seen from Table 5, in Example 16, the concentrations of chromium, copper, cadmium, mercury, and lead in the wastewater were all reduced to below the lower limit of quantitation. It was confirmed that the heavy metal treatment agent of the present invention can effectively treat elements or compounds thereof in Groups 6, 11, 12, and 14. It is also suggested that treatment using the heavy metal treatment agent of the present invention in the above-described system is applicable to municipal waste incineration plant smoke washing wastewater.

[0096] The results of the nickel and zinc-containing wastewater treatment in Table 4 and the composite element-containing wastewater treatment in Table 5 showed similar trends to those of the incineration ash treatment in Table 1, the copper-containing wastewater treatment in Table 2, and the various element treatment tests in Table 3.

[0097] The above results suggest that the heavy metal treatment agent of the present invention, due to its structural characteristics, reacts well with elements of Groups 6 to 16 or compounds thereof to form water-insoluble aggregates (flocs), thereby providing excellent treatment performance and high usefulness.

[0098] [Complex Element-Containing Wastewater Treatment 2] Test wastewater containing arsenic (Group 15) at a concentration of 0.5 mg / L and selenium (Group 16) at a concentration of 0.5 mg / L was prepared in advance. While stirring 200 mL of the test wastewater at 200 rpm, the heavy metal treatment agent shown in Table 6 was added in an amount such that the dithiocarbamate group content in the heavy metal treatment agent was the same as that of the wastewater, and the mixture was stirred for 10 minutes. Subsequently, a 38% aqueous solution of ferric chloride as an inorganic flocculant was added in the amount shown in Table 6 and stirred for 5 minutes. The pH was then adjusted to 8 using an aqueous sodium hydroxide solution. A polymer flocculant was then added and the mixture was stirred for 2 minutes at 20 rpm. After stirring, the mixture was left to stand for 10 minutes, and the flocs were filtered off using filter paper. The concentrations of each element in the filtrate were measured. The arsenic and selenium concentrations in the filtrate were measured using an ICP atomic emission spectrometer. The results are shown in Table 6.

[0099]

[0100] As can be seen from Table 6, the arsenic and selenium concentrations in the filtrate of Example 17 were lower than those of Comparative Example 12, and the arsenic and selenium concentrations in the wastewater were reduced to below the lower limit of quantitation. It was confirmed that the heavy metal treatment agent of the present invention can effectively treat elements of Groups 15 and 16 or their compounds. It is also suggested that treatment using the heavy metal treatment agent of the present invention in the above system can be applied to soil treatment wastewater.

[0101] [Hexavalent Chromium-Containing Wastewater Treatment 1] Test wastewater containing 20 mg / L of hexavalent chromium (Group 6) was prepared in advance. While stirring 200 mL of the test wastewater at 200 rpm, the heavy metal treatment agent shown in Table 7 was added in an amount such that the dithiocarbamate group content in the heavy metal treatment agent was the same as that of the wastewater, and the mixture was stirred for 10 minutes. A polymer flocculant was then added and the mixture was stirred at 20 rpm for 2 minutes. After stirring, the mixture was allowed to stand for 10 minutes, and the flocs were filtered off with filter paper. The hexavalent chromium concentration of the filtrate was measured. The hexavalent chromium concentration in the filtrate was measured using the diphenylcarbazide absorptiometry method according to JIS K0102 65.2.1. The results are shown in Table 7.

[0102]

[0103] Table 7 confirms that the hexavalent chromium concentration in the filtrate of Example 18 is lower than that of Comparative Example 13, and that the heavy metal treatment agent of the present invention can effectively treat Group 6 elements or compounds thereof. It also suggests that treatment using the heavy metal treatment agent of the present invention in the above system is applicable to plating factory wastewater containing hexavalent chromium.

[0104] [Hexavalent Chromium-Containing Wastewater Treatment 2] Test wastewater containing 20 mg / L of hexavalent chromium (Group 6) was prepared in advance. While stirring 200 mL of the test wastewater at 200 rpm, the heavy metal treatment agent shown in Table 8 was added in the amount shown in Table 8 so that the dithiocarbamate group content in the heavy metal treatment agent was the same as that of the wastewater, and the mixture was stirred for 10 minutes. Subsequently, a 38% aqueous solution of ferric chloride was added as an inorganic flocculant in the amount shown in Table 8, and the mixture was stirred for 5 minutes. The pH was then adjusted to 8 using aqueous sodium hydroxide. A polymer flocculant was then added and the mixture was stirred for 2 minutes at 20 rpm. After stirring, the mixture was allowed to stand for 10 minutes, and the flocs were filtered off using filter paper. The hexavalent chromium concentration and chromium concentration of the filtrate were measured. The hexavalent chromium concentration in the filtrate was measured using the diphenylcarbazide absorptiometry method in accordance with JIS K0102 65.2.1, and the chromium concentration was measured using an ICP atomic emission spectrometer. In Example 20 and Comparative Example 15, the same procedure as above was carried out except that no polymer flocculant was added. The results are shown in Table 8.

[0105]

[0106] Table 8 shows that the hexavalent chromium and chromium concentrations in the filtrate of Examples 19 and 20 were lower than those of Comparative Examples 14 and 15. This confirms that the heavy metal treatment agent of the present invention can effectively treat Group 6 elements or their compounds by using an inorganic flocculant in combination with the polymer flocculant, regardless of whether a polymer flocculant was used. Example 19, which used a polymer flocculant and an inorganic flocculant, had an even lower chromium concentration after treatment. This confirms that the combined use of the heavy metal treatment agent of the present invention with a polymer flocculant and an inorganic flocculant improves the treatment effect of Group 6 elements or their compounds with the heavy metal treatment agent of the present invention. This also suggests that treatment using the heavy metal treatment agent of the present invention in the above system can be applied to chemical industrial wastewater containing hexavalent chromium.

Claims

1. A heavy metal treatment agent comprising at least one dithiocarbamate salt of an amine compound represented by any one of the following formulas (I) to (III): 【Chemistry 1】 (In the formula, m represents an integer of 3 to 6.) 【Chemistry 2】 (In the formula, n Xs each independently represent a hydrogen atom or a 2-aminoethyl group, at least one of which is a 2-aminoethyl group, n represents an integer of 1 to 3, and the total number of nitrogen atoms is 4 to 8.) 【Chemistry 3】 (In the formula, o is an integer of 0 to 2, p is 0 or 1, q is 0 or 1, r is an integer of 0 to 3, the sum of o, p and r is 1 or more, and the total number of nitrogen atoms is 3 to 7.)

2. 2. The heavy metal treatment agent according to claim 1, wherein the amine compound comprises an amine compound represented by the formula (III).

3. The heavy metal treatment agent according to claim 2, wherein the amine compound represented by formula (III) includes at least one selected from the group consisting of amine compounds represented by the following formulas (IIIa), (IIIb) and (IIIc): 【Chemistry 4】

4. 3. The heavy metal treatment agent according to claim 2, wherein the amine compound represented by formula (III) includes each of the amine compounds represented by the following formulas (IIIa) and (IIIb): 【Chemistry 5】

5. 5. The heavy metal treatment agent according to claim 4, wherein the amine compound further comprises an amine compound represented by the following formula (IIIc) as the amine compound represented by the formula (III). 【Chemistry 6】

6. The heavy metal treatment agent according to any one of claims 1 to 5, wherein the amine compound includes each of the amine compounds represented by the formula (I), the formula (II), and the formula (III).

7. The heavy metal treatment agent according to claim 6, wherein the amine compound includes, as the amine compound represented by any one of formulas (I) to (III), each of the amine compounds represented by the following formulas (Ia), (IIa), (IIIa), and (IIIb). 【Chemistry 7】

8. 8. The heavy metal treatment agent according to claim 7, wherein the amine compound further comprises an amine compound represented by the following formula (IIIc) as the amine compound represented by the formula (III). 【Chemistry 8】

9. 2. The heavy metal treatment agent according to claim 1, wherein the amine compound contains the amine compound represented by formula (III), and the amount of the amine compound represented by formula (III) is 10.0% or more and 80.0% or less.

10. 2. The heavy metal treatment agent according to claim 1, wherein the amine compound contains, as the amine compound represented by formula (III), amine compounds represented by the following formulas (IIIa) and (IIIb), and the total amount of the amine compound of formula (IIIa) and the amine compound of formula (IIIb) is 10.0% or more and 50.0% or less. 【Chemistry 9】

11. 2. The heavy metal treatment agent according to claim 1, wherein the amine compound contains the amine compound represented by formula (II), and the amount of the amine compound represented by formula (II) is 5.0% or more and 30.0% or less.

12. 2. The heavy metal treatment agent according to claim 1, wherein the dithiocarbamic acid salt is a sodium dithiocarbamic acid salt.

13. 2. The heavy metal treatment agent according to claim 1, wherein the object to be treated is an element of Groups 6 to 16 of the periodic table or a compound thereof.

14. A method for treating incineration ash containing at least any one of elements or compounds thereof in Groups 6, 12 and 14 of the periodic table, comprising a step of adding the heavy metal treatment agent according to claim 1 to the incineration ash.

15. The method for treating incineration ash according to claim 14, wherein the pH of the eluate of the incineration ash in the Environmental Agency's No. 13 test is 11.5 or higher.

16. A method for treating wastewater containing elements or compounds thereof in Groups 6 to 16 of the periodic table, comprising the step of adding the heavy metal treatment agent according to claim 1 and an iron-based inorganic flocculant and / or an aluminum-based inorganic flocculant to the water to be treated.

17. A method for treating wastewater containing elements or compounds thereof in Groups 6 to 16 of the periodic table, comprising the step of adding the heavy metal treatment agent and polymer flocculant described in claim 1 to the water to be treated.

18. A method for treating wastewater containing elements or compounds thereof in Groups 6 to 16 of the periodic table, comprising the step of adding the heavy metal treatment agent according to claim 1, a polymer coagulant, and an iron-based inorganic coagulant and / or an aluminum-based inorganic coagulant to the water to be treated.

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