JPH05185074A - Treating agent for multivalent metal-containing water and treatment of the same - Google Patents

Abstract

PURPOSE:To unnecessitate the changing of pH of waste water and to prevent the secondary pollution due to redissolution of waste sludge after treatment by fusing water soluble and water insoluble vinyl monomers having a salt forming or complex forming functional group in water based solvent to get a soap-free resin emulsion and adding it to multivalent metal-contg. water. CONSTITUTION:In a reaction vessel, 300 pts. water, 30 pts. acrylic acid and 30 pts. styrene are charged. When the mixture is agitated at a speed of 300rpm, the acrylic acid is dissolved in the water and styrene is in a state of suspension. Next, 0.12 pts. azobisamidinopropane hydrochloride are put in and polymerization is performed under a current of nitrogen at 70 deg.C for 4hrs while stirring and after polymerization is completed, neutralization is performed to get a uniform emulsion. When the emulsion is directly added to multivalent metal- contg. water, the functional group on the surface of the emulsion particles and the metal are combined to lower zeta-potential of the particle surface, permitting the emulsion particles to be flocculated. The emulsion particles capturing multivalent metal, etc., are thus separated from water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment agent and treatment method for polyvalent metal-containing water.

[0002]

2. Description of the Related Art Conventionally, as a method generally used for removing or recovering polyvalent metals in polyvalent metal-containing water such as heavy metal-containing wastewater, an alkaline substance such as slaked lime or caustic soda is added. There is a method of insolubilizing a polyvalent metal in water as a hydroxide to remove or collect an aggregated precipitate. There is also a method of insolubilizing a polyvalent metal by adding a chelating substance such as polyalkyleneamine dithiocarbamic acid to water, and removing or recovering the insoluble matter by filtration (for example, Japanese Patent Publication No. 61-8115). And Japanese Patent Publication No. 1-3549).

[0003]

However, in the above method of adding an alkaline substance, it is necessary to make the system alkaline each time, and when discharging the wastewater after separating and removing or recovering the polyvalent metal, Is required to be neutralized again with an acidic substance, which is industrially very complicated. Further, when the polyvalent metal hydroxide sludge separated and removed or collected is discarded, there is a problem that it may be redissolved to generate secondary pollution depending on the disposal method. Also,
In the method of adding a chelating substance, the metal chelate formation reaction takes time and the sedimentation property is poor. Therefore, it is usually necessary to use a polymer flocculant such as polyacrylamide in combination to accelerate the sedimentation.

[0004]

The present inventors have proposed a treatment agent for removing or recovering polyvalent metals in polyvalent metal-containing water, such as heavy metal-containing wastewater, which does not change the pH after treatment. The present invention has been achieved as a result of intensive studies to obtain a treatment agent that is free from the concern of secondary pollution due to re-dissolution of sludge when it is discarded and has a high reactivity.

That is, the present invention comprises the following [1] to [3]. [1] A radical polymerization initiator (a) containing a water-soluble vinyl-based monomer (a) having a salt-forming or complex-forming functional group and a water-insoluble vinyl-based monomer (b) substantially without using an emulsifier for emulsion polymerization. A treatment agent for polyvalent metal-containing water consisting of a resin emulsion obtained by polymerizing c) in an aqueous solvent [hereinafter referred to as treatment agent (1)]. [2] Water-insoluble vinyl-based monomer (b) and water-soluble vinyl-based monomer (a) optionally having a salt-forming or complex-forming functional group are added to water-soluble polymer having a salt-forming or complex-forming functional group. In the presence of (d), a treatment agent for polyvalent metal-containing water comprising a resin emulsion obtained by polymerizing in a water-based solvent using a radical polymerization initiator (c) substantially without using an emulsifier for emulsion polymerization. [Less than,
Treatment agent (2)]. [3] A method for treating polyvalent metal-containing water, which comprises adding the treatment agent (1) or the treatment agent (2) to the polyvalent metal-containing water and separating the precipitate.

In each of the treating agents (1) and (2) of the present invention, the salt-forming or complex-forming functional group in the water-soluble vinyl monomer (a) is, for example, a carboxyl group, a sulfonic acid group or a sulfuric acid group. Group, aminocarboxylic acid group,
Iminodicarboxylic acid group, xanthogenic acid group, phosphoric acid group,
Examples thereof include thiocarbamic acid group, dithiocarbamic acid group, thiol group, amino group, imino group, phosphomethylamino group, thioureido group, amidooxime group and acid hydrazide group. Of these, a carboxyl group, a sulfonic acid group, a sulfuric acid group, an aminocarboxylic acid group, an iminodicarboxylic acid group, a xanthogenic acid group, a phosphoric acid group, a thiocarbamic acid group, and a dithiocarbamic acid group are alkali metals, ammonium salts and the like. It may be.

Specific examples of preferable water-soluble vinyl monomers (a) having the above-mentioned functional groups include (meth) acrylic acid, styrenesulfonic acid, vinylsulfonic acid and 2-acrylamido-2-methylpropanesulfone. One or more selected from acids, vinylamines, allylamines, dimethylaminoethyl (meth) acrylates, dimethylaminopropyl (meth) acrylamides, and alkali metal salts or ammonium salts of these.

In the treatment agent (2) of the present invention, the salt-forming or complex-forming functional group in the water-soluble polymer (d) is exemplified as the salt-forming or complex-forming functional group in the above (a). The same thing as what was done is mentioned. Specific examples of preferable water-soluble polymers (d) having this functional group include (meth)
Acrylic acid, styrene sulfonic acid, vinyl sulfonic acid,
2-acrylamido-2-methylpropanesulfonic acid,
Examples thereof include vinylamine, allylamine, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and polymers having one or more selected from alkali metal salts or ammonium salts thereof as a constituent unit, and polyethyleneimine.

In each of the treating agents (1) and (2) of the present invention, the water-insoluble vinyl monomer (b) is 25 ° C.
Vinyl monomers having a solubility in water of 10 g / dl or less are mentioned. Examples of this include olefins such as ethylene and propylene, aromatic olefins such as styrene, vinyl esters such as vinyl acetate, dienes such as butadiene and isoprene, vinyl halides such as vinyl chloride, methyl acrylate and acrylic acid. Examples thereof include (meth) acrylic acid esters such as ethyl, methyl methacrylate and butyl acrylate, and other vinyl-based monomers such as acrylonitrile and maleimide.

Further, as (b), a crosslinkable monomer having two or more double bonds can be used. Examples of these include ethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, divinylbenzene, methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, tetraallylethane and the like. Two or more of the above examples (b) may be used in combination.

In the treating agent (1) of the present invention, the weight ratio (a) / (b) of the units (a) and (b) constituting the resin component of the resin emulsion is usually 1/99 to 90/10. ,
It is preferably 10/90 to 80/20. Further, in the treating agent (2) of the invention, among the constituent components of the resin component of the resin emulsion, the total of the units (a) and (d) and (b)
The unit weight ratio [(a) + (d)] / (b) is usually 1
/ 99 to 90/10, preferably 10/90 to 80 /
Twenty. Further, of these, (a) is a component that is optionally used.

When producing the treating agent (1) of the present invention, the total weight of (a) and (b) in the polymerization system when polymerizing in an aqueous solvent is usually 1 to 70% by weight, preferably It is 10 to 60% by weight. Further, the treating agent of the present invention (2)
The total weight of (a), (b) and (d) in the polymerization system when polymerizing in an aqueous solvent is usually 1 to 70% by weight, preferably 10 to 60% by weight. ..

In each of the treating agents (1) and (2) of the present invention, the radical polymerization initiator (c) is not particularly limited, and specific examples thereof include azobisisobutyronitrile and azobisamidinopropane. Azo compounds such as hydrochloride and azobis cyanovaleric acid (salt); and organic peroxides such as benzoyl peroxide and ditertiary butyl peroxide; inorganic peroxides such as potassium persulfate, sodium persulfate and ammonium persulfate (It may be used as a redox initiator in which these inorganic peroxides and a reducing substance such as sodium sulfite, dimethylaminoethanol, dimethylaminobenzoic acid, etc. are combined). Of these, the preferred one is
Azobisamidinopropane hydrochloride and azobiscyanovaleric acid (salt), and water-soluble radical polymerization initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate. The addition amount of (c) is usually 0.001 to 1% by weight based on the vinyl monomer component to be added.

In each of the treating agents (1) and (2) of the present invention, the aqueous solvent may be water (distilled water, ion-exchanged water, tap water, industrial water, etc.) alone, or a water-soluble organic solvent in water ( Alcohols, acetone, etc.) may be included.

In each of the treating agents (1) and (2) of the present invention, when the resin emulsion is polymerized, other additives may be optionally present. Other additives include, for example, a surfactant for assisting emulsification, a chain transfer agent for adjusting the molecular weight of the resulting polymer, and the like. Further, the treatment agent (1) of the present invention,
(2) In addition to the resin emulsion, each may further contain other additives if necessary. Examples of other additives include stabilizers and thickeners for stabilizing the resin emulsion, preservatives for preventing spoilage, and the like.

In each of the treating agents (1) and (2) of the present invention, the size of the micelle particles of the resin emulsion is usually
0.01 to 300 microns, with a preferred range of 0.05 to 100 microns.
If the particle size is smaller than 0.01 micron, it takes time to agglomerate the particles after the reaction with the polyvalent metal or the like in use, and it may be necessary to use an inorganic coagulant or a polymer coagulant together. On the other hand, when it exceeds 300 microns, the emulsion or dispersion stability in water is poor, and the adsorption efficiency of polyvalent metals and the like is poor.

The treating agents (1) and (2) of the present invention are both
It consists of a resin emulsion obtained by soap-free emulsion polymerization, substantially without using an emulsifier for emulsion polymerization. In this soap-free emulsion polymerization method, by balancing the water-soluble portion and the water-insoluble portion of the resulting polymer, the polymer becomes fine particles in the aqueous solvent, resulting in an emulsion or suspension of an aqueous resin, There is an advantage that a stable emulsion can be obtained without poisoning the active particle surface with an emulsifier.

When a resin emulsion is produced using each of the treating agents (1) and (2) of the present invention, any polymerization method such as a batch polymerization method, a continuous tube polymerization method or a semi-continuous polymerization method is used. Good. In the case of the batch-type polymerization method, the solvent component, the vinyl-based monomer component and the radical polymerization initiator may be charged all at once to perform the polymerization, or the vinyl-based monomer component and the radical polymerization initiator may be added dropwise to perform the polymerization. Absent. The polymerization temperature and time are determined by the polymerizability of the monomer and the decomposition temperature and time of the initiator, but the temperature is usually 30 to 130 ° C, preferably 50 ° C to 100 ° C.
Further, the time is several hours to ten and a dozen hours. The stirring condition is an important factor in carrying out the polymerization. If the stirring is insufficient, an emulsion cannot be obtained, and a gelled product is produced or a large amount of residual monomer remains. The particle size and particle size distribution of the polymer particles in the obtained emulsion can be controlled by the stirring speed.

The polyvalent metal-containing water targeted by each of the treating agents (1) and (2) of the present invention includes heavy metals such as copper, chromium, lead, cadmium, mercury and iron, and calcium, magnesium and aluminum. It is water containing other polyvalent metals.

An example of the treatment method of the present invention using the treatment agent (1) or (2) of the present invention will be described, including the action mechanism. First, the treatment agent (1) or (2) of the present invention is directly added to water containing a polyvalent metal or the like, and a little stirring is performed.
With the addition, a bond between the functional group on the surface of the emulsion particles and the metal occurs, and this bond also extends between the particles, and the bond lowers the zeta potential on the surface of the particle to aggregate the emulsion particles. Then, the polyvalent metal can be removed from the water by separating the emulsion particles in which the polyvalent metal or the like is collected from the water. The resin emulsion causes coagulation and precipitation by itself with the reaction with the polyvalent metal and the like, so that the coagulation separation method is usually used as the separation method. The concentrated liquid once coagulated and separated can be further dehydrated by using a coagulant. A usual method can be used as the dehydration method. Usually, a belt press dehydration method, a screw press dehydration method, a centrifugal dehydration method, a vacuum dehydration method and the like can be used.

If necessary, an ordinary flocculant or a neutralizing agent may be used in combination for the flocculation / separation. As the aggregating agent, an inorganic aggregating agent and / or an organic aggregating agent is used. As the inorganic coagulant, a sulfuric acid band, polyaluminum chloride, iron chloride, iron sulfate, slaked lime or the like is used. As the organic coagulant, a polyacrylamide-based polymer coagulant is usually used.

The polymer coagulant is an acrylamide polymer, an acrylamide / acrylic acid (salt) copolymer, acrylamide / acrylic acid (salt) / 2-acrylamido-2 in the case of aggregation and separation for the purpose of concentration. -Methylpropanesulfonic acid (salt) copolymer, acrylamide / (meth) acryloyloxyethyltrimethylammonium chloride copolymer, nonionic, anionic,
Weakly cationic polymers are used. For the purpose of dehydration such as the belt press dehydration method in the item 1, the polymer flocculant is an acrylamide / (meth) acryloyloxyethyltrimethylammonium chloride copolymer or (meth) acryloyloxyethyltrimethylammonium chloride polymer. Cationic polymers such as

[0023]

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Example 1 Heating / cooling / stirring is possible and nitrogen aeration is possible. A reaction vessel was charged with 300 parts of water, 30 parts of acrylic acid and 30 parts of styrene, and stirred at 300 rpm. Acrylic acid dissolved in water and styrene became suspended. Next, 0.12 parts of azobisamidinopropane hydrochloride was charged and polymerization was carried out at 70 ° C. for 4 hours under a nitrogen stream while stirring. Along with the polymerization, the polymerization system gradually became cloudy and became an emulsified state. After the completion of the polymerization, a uniform emulsion was obtained and the reaction rate was 99%. The pH of this emulsion was 2.2, and the emulsion was neutralized to pH 8 with an aqueous sodium hydroxide solution.

Example 2 The same reactor as in Example 1 was charged with 300 parts of water, 45 parts of dimethylaminopropylacrylamide and 30 parts of styrene and stirred at 300 rpm. Dimethylaminopropyl acrylamide dissolved in water and styrene became suspended. Next, add 0.1% of sodium azobiscyanovalerate.
Polymerization was carried out at 70 ° C. for 4 hours under a nitrogen stream while charging 2 parts of the mixture and stirring. Along with the polymerization, the polymerization system gradually became cloudy and became an emulsified state. After the completion of the polymerization, a uniform emulsion was obtained and the reaction rate was 99%.

Example 3 300 parts of water, 15 parts of polyethyleneimine (molecular weight about 70,000) and 30 parts of styrene were charged in the same reactor as in Example 1 and stirred at 300 rpm. Polyethyleneimine was dissolved in water and styrene became suspended. Next, 0.12 parts of sodium azobiscyanovalerate was charged, and polymerization was carried out at 70 ° C. for 4 hours under a nitrogen stream while stirring. Along with the polymerization, the polymerization system gradually became cloudy and became an emulsified state. After the completion of the polymerization, a uniform emulsion was obtained and the reaction rate was 99%.

Examples 4 to 6 The resin emulsions synthesized in Examples 1 to 3 were added to water (pH 6.0) containing 80 ppm of copper ions so that the resin solid content would be 1000 ppm, and the mixture was stirred.
The emulsion colored blue and at the same time coagulated to form a precipitate. When the pH and copper ion concentration of the supernatant were measured, the results shown in Table 1 below were obtained.

Comparative Example 1 When a 1% aqueous sodium hydroxide solution was gradually added dropwise to the copper ion-containing wastewater used in Examples 4 to 6, the system turned blue and then a blue precipitate was gradually deposited. P of the supernatant
When H and copper ion concentrations were measured, the results shown in Table 1 below were obtained.

Comparative Example 2 A commercially available chelating treatment agent was added to the copper ion-containing wastewater used in Examples 4 to 6 so that the solid content was 1000 ppm, and the mixture was stirred. A black-brown precipitate slowly precipitated, and a part thereof aggregated to form a precipitate. Since it takes time for the particles to aggregate and precipitate, it was necessary to add about 2 ppm of a polyacrylamide polymer flocculant to promote the aggregation and precipitation. When the pH and copper ion concentration of the supernatant after the treatment were measured, the results shown in Table 1 below were obtained.

[0029]

[Table 1]

[0030]

The present invention has the following effects. (1) By using the treating agent of the present invention, for example, in the case of waste water from a mining plant, a mine, etc., it is possible to remove heavy metals that become harmful substances. In this case, it is efficient because the pH of the waste water is not changed and it is not necessary to neutralize it unlike the conventional case. In addition, sludge that has been treated and disposed of does not have the risk of secondary pollution due to redissolution. (2) Further, in the case of the above waste water, by using the treatment agent of the present invention, other impurities dissolved in water, for example, a coloring substance such as a dye in the waste water or a water-soluble C such as an organic acid.
It is also possible to simultaneously remove the OD-causing substance and the phosphate ions and nitrate ions contained in the components of phosphorus and nitrogen that enrich water by releasing. Among these impurities, the impurities composed of ionic substances can be removed particularly efficiently. (3) In addition, by a simple operation using the treatment agent of the present invention, useful polyvalent metal in polyvalent metal-containing water in various steps in a mining factory or the like, or removal of an interfering polyvalent metal (hard water) Water softening). Because of the above effects, the water treatment agent of the present invention is extremely practical as a novel water treatment agent.

Claims (7)

[Claims] 1. Radical polymerization initiation of a water-soluble vinyl-based monomer (a) having a salt-forming or complex-forming functional group and a water-insoluble vinyl-based monomer (b) substantially without using an emulsifier for emulsion polymerization. A treatment agent for polyvalent metal-containing water, which comprises a resin emulsion obtained by polymerizing the agent (c) in an aqueous solvent. 2. A water-soluble vinyl monomer (b) and a water-soluble vinyl monomer (a) optionally having a salt-forming or complex-forming functional group are added to a water-soluble vinyl monomer having a salt-forming or complex-forming functional group. Of a polyvalent metal-containing water obtained by polymerizing in a water-based solvent by using a radical polymerization initiator (c) without using an emulsifier for emulsion polymerization in the presence of a water-soluble polymer (d). Processing agent. 3. The salt-forming or complex-forming functional group in (a) is a carboxyl group, a sulfonic acid group, a sulfuric acid group, an aminocarboxylic acid group, an iminodicarboxylic acid group, a xanthogenic acid group, a phosphoric acid group, or thiocarbamine. The treatment agent according to claim 1 or 2, which is an acid group, a dithiocarbamic acid group, a thiol group, an amino group, an imino group, a phosphomethylamino group, a thioureido group, an amidoxime group or an acid hydrazide group. 4. (a) is (meth) acrylic acid, styrenesulfonic acid, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylamine, allylamine, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl. The treatment agent according to any one of claims 1 to 3, which is at least one selected from (meth) acrylamide and alkali metal salts or ammonium salts thereof. 5. The salt-forming or complex-forming functional group in (d) is a carboxyl group, a sulfonic acid group, a sulfuric acid group, an aminocarboxylic acid group, an iminodicarboxylic acid group, a xanthogenic acid group, a phosphoric acid group, or thiocarbamine. The treatment agent according to claim 2, which is an acid group, a dithiocarbamic acid group, a thiol group, an amino group, an imino group, a phosphomethylamino group, a thioureido group, an amidoxime group or an acid hydrazide group. 6. (d) is (meth) acrylic acid, styrenesulfonic acid, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylamine, allylamine, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl. The water treatment agent for heavy metal-containing water according to claim 2, which is a polymer having a structural unit of at least one selected from (meth) acrylamide and alkali metal salts or ammonium salts thereof, or polyethyleneimine. 7. A method for treating polyvalent metal-containing water, which comprises adding the treatment agent according to claim 1 to polyvalent metal-containing water and separating a precipitate.