JP2002177770A - Heavy metal adsorbent and method of preparing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy metal adsorbent which is capable of removing heavy metals by a gaseous phase and liquid phase and a method of preparing the same. SOLUTION: This heavy metal adsorbent is prepared by impregnating a solution of 0.2 mass% to saturation concentration of >=1 kind of chelate forming group-containing compounds selected from the group consisting of 1,2- diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and ethylene-diaminetetraacetic acid with porous materials of >=1 kinds selected from the group consisting of activated carbon, zeolite, diatomaceous earth, natural sand and ceramics to bond these compounds to the porous compounds. The heavy metal adsorbent is capable of removing the heavy metals by the gaseous phase method and the liquid phase method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy metal adsorbent in which a compound containing a chelating group is bonded to a porous substance, its use, and a method for producing the heavy metal adsorbent.

[0002]

2. Description of the Related Art General industrial waste, solvent manufacturing process waste,
Industrial waste of synthetic rubber manufacturing process waste, various research facilities,
Medical waste and household refuse contain heavy metal compounds such as mercury, copper, lead, zinc, chromium, nickel, cadmium, titanium, manganese, cobalt, arsenic, tin, and bismuth. These various types of waste are processed according to the original materials.Wastes mainly composed of glass, iron, aluminum, etc. are reused after being separated and collected, but most of them are disposed of by incineration. ing. For this reason,
A large amount of heavy metals is contained in the waste gas from which the heavy metal-containing combustion gas, the combustion gas and the combustion ash from the incineration treatment are washed.

In addition, when dioxin, which is considered to be the most carcinogenic compound, is generated, unburned organic substances resulting from incomplete combustion of refuse are burned on the surface of the combustion ash in a relatively low temperature range using a heavy metal compound such as copper chloride. There is a report that dioxin is generated by the action.

However, many of these heavy metals and heavy metal compounds are harmful, and the influence of pollution on the entire environment such as air, water, and soil is great. For this reason, regarding the treatment of waste gas generated by the incineration of general waste and industrial waste, pollution control values such as the Air Pollution Control Law, the Odor Control Law, and the Water Pollution Control Law have been established. Is required.

Conventionally, as treatment of heavy metal compounds contained in such heavy metal-containing wastewater, most of them are generally removed by coagulation and sedimentation as hydroxides and sulfides, but they are particularly strictly regulated by environmental standards. Mercury, cadmium,
It is difficult to always reduce the lead or the like to a specified value or less only by coagulation sedimentation. Therefore, as a finishing step after the coagulation sedimentation and filtration operations, a treatment for absorbing and removing heavy metal compounds by a chelate resin is performed.

A chelate resin used for such a heavy metal compound removal treatment is obtained by bonding a functional group capable of forming a chelate to a three-dimensionally cross-linked polymer substrate, for example, vinyl chloride. And a chelate resin in which a biscarboxymethylamine group is a functional group, and a chelate resin in which a biscarboxymethylamine group is bonded to a copolymer of styrene and divinylbenzene.

[0007]

However, when hydrazine is bonded to vinyl chloride, there is a risk that hydrazine may be ignited. In addition, in order to bond hydrazine to vinyl chloride, it takes a long time to produce a three-dimensional crosslinked product, and it is not easy to bond hydrazine serving as a chelating group to this.

As a conventional technique, a bead-like chelating resin is widely used for removing harmful heavy metals such as cobalt, nickel, mercury and copper.
It is difficult to efficiently adsorb and separate low concentrations of dissolved metal ions, requiring a large amount of resin.

[0009] In addition, many chelate resins are generally in the form of beads which are insoluble in water, and those having a large internal surface area as a porous material are used in order to enhance the adsorption capacity. was there. On the other hand, when the particle size of the chelate resin is reduced to increase the contact area with water in order to increase the adsorption speed, there is a disadvantage that handling of the resin is troublesome and the liquid flow resistance to the resin packed layer increases. .

[0010] In addition, for example, regarding the removal of lead ions,
Lead ions are removed by passing water containing lead ions through a container filled with chelating resin.However, when the space velocity of the lead ion-containing water increases, the lead ion removal performance drops sharply. It takes time to remove lead, which must be suppressed. Since the amount of lead adsorbed by the chelate resin is small, it is necessary to fill a large container with a large amount of the chelate resin, which requires an increase in the size of the lead removing device.

Further, in the waste water to be subjected to the adsorption treatment with a chelate resin or a weakly acidic cation exchange resin, etc., in addition to a trace amount of the SS component which has leaked and filtered, a fine heavy metal hydroxide,
Carbonates, silicates, and in some cases, oxides of heavy metals, etc., are present. These heavy metal hydroxides, etc., are not adsorbed and removed by the chelating resin or the weakly acidic cation exchange resin, so that a trace amount of heavy metal leaks. At the same time, the concentration of heavy metals in the treated water is not constant, and there is a variation defect.

Further, washing water of combustion ash of industrial wastes and the like exhibits alkalinity, and the adsorption and removal operation is performed by setting this to a substantially neutral region. However, if a resin is used as the base, the durability of the chelating resin is inferior. Not only does the chelating ability decrease, but also the chelating resin itself deteriorates due to the deterioration of the substrate itself. in addition,
Since commercially available chelate resins are generally expensive, their use in treating heavy metal-containing effluents that must be treated in large quantities can be costly.

Further, since the water-soluble heavy metal contained in the washing water of the combustion waste gas is present in the solution as heavy metal ions, the heavy metal can be captured by the chelating resin.
However, heavy metal compounds contained in the waste gas are present as oxides as a result of the combustion. For this reason, depending on the type of heavy metal, it is not possible to remove the heavy metal by using a chelate resin, and there has been no known technique for removing a heavy metal from a heavy metal-containing gas by a chelating action.

On the other hand, as a method for removing heavy metals, Japanese Unexamined Patent Publication No.
Japanese Patent No. 182984 discloses a method for removing heavy metal ions from heavy metal ion-containing water, which comprises contacting heavy metal ion-containing water with calcium phosphate-based ceramic particles. It is described that bone charcoal particles are preferable as the calcium phosphate-based ceramic particles, and the amount of heavy metal adsorbed is larger than that of chelate resin, and it is said that the heavy metal removing device can be downsized. However, the present inventors have confirmed that the ability of activated carbon to adsorb heavy metals is not yet sufficient.

[0015]

The above objects are achieved by the following (1) to (7).

(1) 1,2-diaminoethane, 1,2
-0.2% by mass of one or more chelating group-containing compounds selected from the group consisting of diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and ethylenediaminetetraacetic acid. A heavy metal adsorbent obtained by impregnating a solution having a saturated concentration with at least one porous material selected from the group consisting of activated carbon, zeolite, diatomaceous earth, natural sand, and ceramics to bind the compound to the porous material .

(2) The binding amount of the chelate-forming group-containing compound to the porous substance is 1 to 10 of the porous substance.
Mass% by mass, the heavy metal adsorbent according to the above (1).

(3) The heavy metal adsorbent according to claim 1 or 2, wherein the porous material has a particle size of 4 to 40 mesh.

(4) The heavy metal adsorbent according to any one of the above (1) to (3), wherein the water content is 5 to 40% by mass.

(5) The above (1) to (1) to remove heavy metals or heavy metal compounds contained in the heavy metal-containing gas.
The heavy metal adsorbent according to any one of (4).

(6) The heavy metal adsorbent according to any one of the above (1) to (5), which removes heavy metal ions, heavy metals or heavy metal compounds contained in the heavy metal-containing solution.

(7) 1,2-diaminoethane, 1,2
-0.2% by mass of one or more chelating group-containing compounds selected from the group consisting of diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and ethylenediaminetetraacetic acid. A method for producing a heavy metal adsorbent, comprising impregnating a porous substance in a solution having a saturated concentration from the above to bind the compound to the porous substance, and then separating and drying the porous substance from the solution. .

[0023]

DETAILED DESCRIPTION OF THE INVENTION First, the present invention relates to 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and One or more compounds selected from the group consisting of activated carbon, zeolite, diatomaceous earth, natural sands, and ceramics are added to a solution of one or more chelating group-containing compounds selected from the group consisting of ethylenediaminetetraacetic acid at a concentration of 0.2% by mass to a saturated concentration. An object of the present invention is to provide a heavy metal adsorbent obtained by impregnating a porous substance as described above and binding the compound to the porous substance. Conventionally, a chelate-forming group is bonded to a three-dimensional crosslinked resin as a substrate, but it is difficult to produce a three-dimensional crosslinked body having sufficient durability because it is not excellent in durability. Was. However, according to the present invention, it has been found that by using an inorganic porous substance such as activated carbon as a base, a heavy metal adsorbent having excellent durability, low cost and excellent heavy metal binding ability can be obtained. is there.

The porous substance used in the heavy metal adsorbent of the present invention is not particularly limited as long as it is mainly composed of an inorganic substance. Activated carbon, zeolite, natural sand,
Ceramics or the like can be used.

As the porous substance, for the purpose of use as a heavy metal adsorbent, the porous substance preferably has a particle size passing through 4 to 40 mesh, particularly preferably
It is preferably 4 to 32 mesh, more preferably 6 to 20 mesh. The heavy metal adsorbent of the present invention can adsorb and remove heavy metals and heavy metal compounds contained in the gas phase, and can also adsorb heavy metal ions, heavy metals, and heavy metal compounds in the solution. In any case, resistance to fluid pressure is maintained, pressure loss is small, and rapid fluid treatment can be ensured.
The particle size of the porous substance can be appropriately selected within the above range in consideration of the pressure loss and the flow rate when the heavy metal-containing solution or the heavy metal-containing gas is brought into contact with the heavy metal adsorbent.

In the present invention, the porous substance is not particularly limited in physical properties as long as it has a large number of pores not only on the surface but also on the inside.
700 to 1500 m ² / g, more preferably a specific surface area of 10
40 to 1400 m ² / g. The internal volume is 70
0 to 1800 m ³ / g, more preferably 900 to 150
It is preferably 0 m ³ / g. In particular, the adsorptive power of the substance often depends on the pore diameter, and the average pore diameter of the porous substance is preferably 20 to 50 °, more preferably 20 to 40 °.

In the present invention, it is preferable to use activated carbon as the porous substance. In general, activated carbon is used for solvent recovery,
Porous carbon used for gas purification, deodorizing agents, decolorizing agents, etc. It has many fine pores of several centimeters per ten million. For this reason, the property of adsorbing substances is extremely strong. Wood, sawdust, coconut shells, lignin and other plant-based materials, bovine bone, chicken dung, blood charcoal and other animal-based materials, as well as lignite, lignite, large coal, and coal There is a product obtained by carbonizing and then activating and purifying. In the present invention, any of the above-mentioned compounds containing a chelate-forming group can be used as long as the compound can be bonded to the porous substance. However, from the viewpoints of heavy metal adsorption power and durability, plants, such as bolls, combs, and palms, are preferred, and particularly preferable are activated carbons such as bolls, combs, and coconut shells. Although the reason is not clear, since these activated carbons have more hydroxyl groups than other types, it is considered that the hydroxyl groups having a salt-forming ability improve the heavy metal binding ability. The interior of the activated carbon is extremely porous and has a strong adsorption capacity for various gases and inorganic, organic substances, colloid particles and the like in the solution, and the heavy metal adsorbent of the present invention has an excellent heavy metal adsorption capacity. Although it is considered that such a porous substance also acts as one of the factors that exerts the effect described above, the effect is superior to that of the porous substance alone as shown in Examples.

In the present invention, zeolite can be used as the porous substance. Zeolite is a type of silicate containing aluminum (aluminosilicate), also called zeolite, and is characterized by a structure occupied by fine pores. Natural products may be used, but synthetic zeolites may be used. Synthetic zeolites are preferred because their pores are aligned in angstrom units on the order of molecular size. The fine pores are used because molecules corresponding to the diameter of the pores are absorbed and desorbed. Specifically, ZCP-50 and ZCE-50 (trade names, manufactured by Catalyst Chemicals) and TSZ-300, TSZ-500, and TSZ-60 (trade names, manufactured by Toyo Soda Kogyo Co., Ltd.)
0, TSZ-700, trade name LZ-Y manufactured by Union Showa
52, LZ-Y62, SK-500 and the like.

In the present invention, diatomaceous earth can be used as the porous material. Diatomaceous earth is a siliceous deposit consisting of the remains of a diatom, a unicellular algae. It is porous and used after purification.

In the present invention, porous ceramics can be used as the substrate. Ceramics is a general term for what is usually obtained by thermally processing non-heavy metal inorganic materials,
Excellent heat and corrosion resistance. The term “ceramics” in the present invention includes ceramics, glass powder, cement powder, ferrite, or a mixture thereof as long as it has the above-mentioned specific properties such as specific surface area and internal surface area.

Similarly, if the material is porous, the material is not limited to a porous material, and natural sand or porous sand obtained by further finely pulverizing porous lava may be used.

Examples of the compound containing a chelating group bonded to the porous substance in the present invention include ethylenediamines, ethylenediaminetetraacetic acid, and salts thereof. The ethylenediamines, a series of compounds represented by _{H 2 N (CH 2 CH 2} NH) n H, n is the compound of 1-5 can be preferably used. Also, -NH located at the molecular end
Or -N (CH ₂ COOH) ₂ in place of the _2, -N its alkali metal salts (CH ₂ COONa) ₂ is preferred. Bound compounds are also preferred and can be used. Specifically, the compound containing a chelate-forming group used in the present invention includes 1, 1
2-diaminoethane, 1,2-diaminopropane, 1,
2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene hexamine, or a -CH ₂ COOH substituents, and these alkali metal salts, preferably used, for example, ethylenediaminetetraacetic acid and sodium ethylenediaminetetraacetate be able to. In the present invention, one of these may be used alone or two or more of them may be used in combination. However, the chelate-forming group-containing compound is particularly preferably an ethylenediamine, especially 1,2-diaminoethane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine or ethylenediaminetetraacetic acid. In particular, it is excellent in the adsorptive power of heavy metals contained in acidic solutions such as industrial waste water and washing water of combustion ash of industrial waste. When the porous substance is reacted with the above compound,
Although the reaction mechanism is unknown, an adsorbent having excellent heavy metal adsorption power can actually be obtained. Although details are unknown, it is considered that the compound binds to the surface of the porous material.

As the heavy metal adsorbent of the present invention, in addition to the above compounds, other compounds may be bonded to the porous substance. Such other compounds include hydroxymethylcellulose, polyalcohols, polyamines, hydroxamic acids, amino acids, iminodiacetic acid and the like. For example, when hydroxymethylcellulose is bonded to activated carbon together with 1,2-diaminoethane, the bonding of 1,2-diaminoethane to the porous material becomes stronger.

The bonding between molecules can be achieved by both atoms or atomic groups sending out one electron at a time and sharing them as a pair. A covalent bond, in which the outermost electron moves from one to the other and becomes positive or negative. An ionic bond is formed by electrically attracting, and two electrons emitted by one atom or group move to the orbit of another atom or group to form a coordinate bond. is there. The meaning of "bond" of the chelating group-containing compound to the porous substance in the present invention is not limited to a covalent bond as described above, and includes an ionic bond and a hydrogen bond, but is not limited to a bond between atoms or atomic groups. It also includes a carrier that is simply physically adsorbed and bonded.

In the heavy metal adsorbent of the present invention, the binding amount of the compound containing a chelating group is 1 to 10% by mass of the porous substance, more preferably 1 to 5% by mass, particularly preferably 1 to 2% by mass. %. This is because the porous substance is porous and therefore has a large surface area per unit mass, and can bind the chelate-forming group-containing compound in the above range, and can exhibit excellent heavy metal adsorption power.

The porous material used for the substrate may have a different activity depending on the amount of water retained, heating, and the like. However, the heavy metal adsorbent of the present invention has a water content before use of 5 to 40% by mass, more preferably 5 to 20% by mass.
It is preferably adjusted to 5% by mass, especially 5 to 10% by mass. In particular, when a heavy metal-containing gas is introduced into a heavy metal absorbing device filled with the heavy metal adsorbent in order to remove heavy metals contained in the combustion gas, this range is particularly excellent in heavy metal adsorption ability. It should be noted that the heavy metal treatment capacity varies depending on the amount of heavy metals and heavy metal compounds contained in the treatment fluid, the temperature of the treatment fluid, and the like. Therefore, a suitable amount of water can be appropriately selected in actual use. However, the heavy metal adsorbent of the present invention is also excellent in adsorbing heavy metals in a liquid phase, and in such a case, the water content does not particularly matter.

The second aspect of the present invention is the use of the above heavy metal adsorbent.

The heavy metal adsorbent of the present invention is obtained by binding a chelate-forming group-containing compound to the above-mentioned porous substance, and can be used as it is as a heavy metal adsorbent. In this case, any gas or liquid can be used as long as it contains a heavy metal. Hitherto, chelate adsorption of heavy metals by a gas phase method has not been known, and was achieved for the first time by the present invention. That is, conventionally, heavy metals contained in waste gas have been dissolved in a solution and converted into heavy metal ions and then treated with a chelating resin, but according to the heavy metal adsorbent of the present invention, the heavy metal-containing gas is directly treated. You can do it.

As such heavy metal-containing gas, there are incineration waste gases such as municipal waste incineration plants, industrial wastes, and medical wastes. When removing heavy metals from the waste gas, heavy metals contained in the waste gas are removed in advance by a method other than chelation, for example, coagulation separation by cooling of a high-temperature gas, and further, heavy metals contained in the waste gas are removed as a finishing step. Preferably, the compound is adsorbed. The heavy metals that can be removed from such waste gases by the gas phase method include mercury, silver, gold,
Platinum, zinc, lead, tin, copper, manganese, chromium, iron, cadmium, uranium, vanadium and other heavy metals or compounds of these oxides, sulfides and the like. It is excellent in the adsorption amount of heavy metals such as zinc, tin, copper and vanadium or oxides thereof. The heavy metal adsorbent of the present invention is intended particularly for the removal of heavy metals contained in the water, whereby heavy metals such as copper, which are considered to have a catalytic action at the time of dioxin generation, can also be removed.

On the other hand, as the heavy metal-containing solution, various types of industrial wastewater, experimental laboratory wastewater, hospital wastewater, mine wastewater, and smoke washing wastewater from municipal waste incineration plants can be used. There is no particular limitation on the amount of heavy metal contained in such a heavy metal-containing solution, but the heavy metal adsorption power depends on the amount of binding of the chelate-forming group-containing compound. If heavy metals contained in the wastewater to be treated are separated by a method other than adsorption, heavy metals can be more efficiently removed by adsorption. For this reason, alkali is added to the target treatment wastewater to hydroxide heavy metals, the heavy metal hydroxide is adjusted to a pH at which the solubility of the heavy metal hydroxide is minimized, and the heavy metal hydroxide is agglomerated, and solid-liquid separation means such as sedimentation is used. It is preferable to perform a treatment such as separation into a precipitate and supernatant water. When fine flocs of heavy metals are present in the obtained supernatant water, the supernatant water is filtered to remove fine flocs, and then the remaining heavy metal ions are adsorbed and removed by the heavy metal adsorbent of the present invention.

To use the heavy metal adsorbent of the present invention, the liquid property of the treated wastewater is adjusted to the most preferable pH for the adsorption of each heavy metal. For example, in the case of vanadium, the pH is 2-3 with nitric acid.
When adjusted to a high value, it is excellent in the adsorption of heavy metals, particularly vanadium. Therefore, in order to remove heavy metals from the washing liquid of combustion waste gas containing a large amount of vanadium, the pH of the liquid should be adjusted to pH 2-3.
It is preferable to adjust to. The liquid properties of the heavy metal-containing solution can be easily adjusted by adding hydrochloric acid, sulfuric acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, etc., aqua regia, hydrogen fluoride, etc. Although it can be adjusted, it is preferable to appropriately select an acid to be used depending on the heavy metal to be removed. As described above, it is preferable to use nitric acid for adsorption of vanadium, but it is preferable to use hydrochloric acid for adsorption and removal of mercury, and it is preferable to use sodium hypochlorite for other heavy metals. . All are excellent in solubility for a specific heavy metal. In addition, sodium hypochlorite, which can be used in a wide range, is particularly preferable because sodium hypochlorite itself is a compound that can be used as a bleaching agent, a disinfectant and a disinfectant, and also has an effect of disinfecting a treated waste liquid.

The heavy metal adsorbent of the present invention uses a conventional three-dimensional crosslinked resin because it is hardly affected by fluctuations in pH and components contained in treated wastewater because a porous substance is used. It is much more durable than the case. Heavy metals that can be removed by such a liquid phase method include heavy metals such as mercury, silver, gold, platinum, zinc, lead, tin, copper, manganese, chromium, iron, cadmium, uranium, and vanadium or oxides thereof. The heavy metal adsorbent of the present invention is particularly excellent in the adsorption amount of each of mercury, lead, zinc, tin, copper, and vanadium ions.

In the third aspect of the present invention, 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine,
A porous material is impregnated with a solution having a saturation concentration of 0.2% by mass or more of at least one chelate-forming group-containing compound selected from the group consisting of tetraethylenepentamine, pentaethylenehexamine and ethylenediaminetetraacetic acid, and the compound is impregnated with the compound. A method for producing a heavy metal adsorbent, comprising binding to a porous substance, and then separating the porous substance from the solution and drying.

By impregnating a porous material in a solution in which the compound is dissolved, a compound containing a chelate-forming group can be bonded to the substrate. By such a simple reaction, a heavy metal adsorbent having an extremely excellent heavy metal removing effect can be obtained. Can be manufactured. The chelate-forming group-containing compound may be used alone or in combination of two or more. Further, in addition to these compounds, other compounds containing a chelating group as a functional group, for example, polyalcohol, polyamine,
Hydroxamic acid, an amino acid, iminodiacetic acid, or the like may be reacted with the porous substance and bonded. In this case, a polyalcohol or the like may be bonded to the porous material in advance, and then the resulting porous material may be bonded to an ethylenediamine or the like. As a result of the binding to, the impregnation treatment may be performed at the same time as long as the heavy metal adsorption ability is finally exhibited.

In the method of the present invention, 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine,
Tetraethylenepentamine, pentaethylenehexamine, and ethylenediaminetetraacetic acid have different saturation concentrations, respectively. However, the concentration ranges from 0.2% by mass to the saturation concentration, more preferably from 0.4 to 10% by mass, particularly from 1.8 to 10% by mass. 2.5
It is preferred to impregnate the solution by weight. Within this range, the chelate-forming group-containing compound can be sufficiently bonded to the porous substance.

As the porous substance to be impregnated with the solution of the compound containing a chelate-forming group, those which are commercially available can be used as they are. However, it is preferable to wash in advance in order to remove water-soluble substances contained in the porous substance or other impurities. For example, it is preferable to pre-treat the porous material by charging water and the porous material into a storage tank, stirring the water, and washing the waste water until the washing water is no longer colored. The pretreated porous substance may proceed to the next step as it is, or may be used after drying. As such drying, a dryer may be used in addition to solar drying and natural drying.

Next, the porous substance is introduced into a solution of a compound containing a chelate-forming group, and the compound containing a chelate-forming group is bound to the porous substance. For example, the solution is added for 0.5 to 18 hours. More preferably, the impregnation is performed for 2 to 15 hours, particularly 6 to 10 hours. This solution is preferably stirred, and the stirring speed is preferably 0.5 to 5 rpm, more preferably 1.0 to 1.5 rpm.

The end of the reaction can be determined by weighing the substance. Next, the porous substance is separated from the impregnation solution and dried. As such drying, a dryer may be used in addition to solar drying and natural drying.

In the present invention, the binding amount of the chelate-forming group-containing compound is 40 to 80% by mass of the porous substance as described above, but it is unclear how the compound can be bound by this action. . However, even if the heavy metal is actually adsorbed in the liquid phase from the heavy metal-containing wastewater, for example, the heavy metal binding ability does not deteriorate over a long period of time, and even if the heavy metal adsorbent is washed with an aqueous solution, the chelate-forming group-containing compound is removed. It does not separate and exhibits sufficient heavy metal adsorption capacity. This is a result of the fact that the chelate-forming group-containing compound impregnated inside the porous body is firmly bound inside the pores because the substrate is porous. This enables long-term continuous use in the gas phase method and the liquid phase method. The binding amount of the chelate-forming group-containing compound to the porous substance was calculated from the dry weight of the product relative to the weight of the porous substance before immersion in the compound-containing solution.

[0050]

Next, the present invention will be described in more detail with reference to examples. (Example 1) 600 kg of activated carbon (specific surface area 1040 m
² / g, internal volume 1500 m ³ / g, average pore size 20-5
(0Å, 6-32 mesh) was put into a stirring tank, and drainage washing was repeated 30 times with fresh water obtained by filtering industrial water. When the waste water disappeared, activated carbon was poured into a basket and drained, followed by drying on the sun. 500% of a 2% by weight solution of ethylenediamine
Liter was prepared, and sun-dried activated carbon was added thereto. The mixture was stirred at 1 to 5 rpm for 6 hours to bind ethylenediamine to the activated carbon.

Example 2 12 k of the heavy metal adsorbent obtained in Example 1 was applied to a column having an inner diameter of 200 mm and a length of 1500 mm.
g, using nitric acid for the vanadium solution, hydrochloric acid for the mercury solution, and sodium hypochlorite for the other solutions, appropriately adjusting the pH to 0 to 11, and converting to ion amount. Then, a 0.5 mg / liter aqueous solution containing heavy metal ions was passed through the column at SV = 5 / Hr.
The heavy metal adsorption amount at each pH was measured. In addition, each heavy metal ion-containing solution was manufactured by Kojundo Chemical Laboratory Co., Ltd.
u ³⁺ solution, Ag ⁺ solution, Cu ²⁺ solution, Cd ² + solution, Zn
^{A 2+} solution, a V ²⁺ solution, a Pb ²⁺ solution, a Cr ³⁺ solution, a Co ²⁺ solution, and a Ni ²⁺ solution were used. The results are shown in FIG.

Example 3 A vanadium gas containing the heavy metal adsorbent obtained in Example 1 packed in a column having an inner diameter of 12 mm and a length of 1000 mm and containing 4.2 mg / m ³ of hydrogen was added thereto. Was passed at SV = 1000 / Hr. Vanadium gas was passed until the outlet concentration reached 4.2 mg / m ^3, that is, the saturated concentration. FIG. 2 shows the result of measuring the gas flow rate at the outlet gas phase concentration.

(Comparative Example 1) The same operation as in Example 3 was carried out, except that the activated carbon used in Example 1 before the binding of ethylenediamine was used instead of the heavy metal adsorbent of Example 1, and ventilation was performed at the outlet gas phase concentration. The gas volume was measured. The results are shown in FIG.

Example 4 A heavy metal adsorption / removal treatment was carried out using the liquid heavy metal continuous treatment apparatus shown in FIG. First, the combustion smoke in the incineration plant was washed with water to obtain a combustion smoke washing liquid. After adjusting the pH of the combustion smoke washing solution to 2 to 3 with sodium hypochlorite, a filtrate was obtained with a filter. This solution was introduced into the heavy metal adsorption tower filled with the heavy metal adsorbent of Example 1. Heavy metal adsorption tower, inner diameter 100mm, height 500mm
And a column filled with a heavy metal adsorbent was used by connecting two towers. The flow rate was SV = 2 to 15 / hr. The vanadium concentration at the inlet of the liquid phase heavy metal adsorption tower and the vanadium concentration at the outlet were measured. FIG. 4 shows the results.

Example 5 A heavy metal adsorption / removal treatment was carried out using the continuous gas phase heavy metal treatment apparatus shown in FIG. First, the combustion smoke cooled in the incineration plant was cooled again to a temperature of 70 to 30 ° C. by the heat exchanger. Next, after introducing into the water remover, it was introduced into the heavy metal adsorption tower filled with the heavy metal adsorbent of Example 1. The heavy metal adsorption tower has a tower cross-sectional area of 2.544.
m ² , filling height 600 mm, filling amount of heavy metal adsorbent 15
It was 26 liters, which was used by connecting two towers. The flow rate was SV = 3 / hr. The vanadium concentration at the entrance of the gaseous heavy metal adsorption tower and the vanadium concentration at the exit were measured.
The vanadium concentration at the entrance of the heavy metal adsorption tower was 2.22 to 2.2.
Whereas a 35 mg / m ^3, vanadium concentration in the outlet was 0.019~0.006mg / m ^3.

(Results) From Example 2, the heavy metal adsorbent of the present invention adsorbs each heavy metal effectively. In particular, vanadium ions are remarkably adsorbed on heavy metals in the pH range of 2-3.

From the results of Example 3 and Comparative Example 1, it was found that the heavy metal adsorbent of the present invention had an adsorbing power of vanadium approximately 100 times that of activated carbon. This is considered to indicate that the heavy metal adsorbent of the present invention adsorbs the heavy metal by the action of the chelate-forming group bonded to the activated carbon in addition to the adsorbing power of the activated carbon. According to the present invention, since waste gas containing heavy metals can be treated simply and quickly, especially when used for treating incineration combustion waste gas and this washing liquid, it is inexpensive and also uses conventional facilities as it is to absorb heavy metals. Can be done.

Using the heavy metal adsorbent of the present invention to adsorb and remove heavy metals contained in the washing liquid of the combustion smoke discharged from the incineration plant treatment facility, as shown in FIG.
It could be reduced to about 1 mg / m ³ . In addition, heavy metals contained in the combustion smoke discharged from the combustion treatment facility were adsorbed and removed in the gas phase, and showed extremely excellent heavy metal adsorption power even in the gas phase.

[0059]

According to the present invention, a heavy metal adsorbent having excellent heavy metal ion adsorption power can be produced by a simple method. The obtained adsorbent can adsorb various types of heavy metals at a high concentration.

[Brief description of the drawings]

FIG. 1 is a graph showing the adsorptive power of heavy metal ion-containing solutions having different pH concentrations by the heavy metal adsorbent of the present invention in Example 2.

FIG. 2 is a diagram showing a relationship between an outlet gas-phase mercury concentration and a gas passing amount in Example 3 and Comparative Example 1.

FIG. 3 is a view showing a liquid-phase heavy metal continuous treatment apparatus used in Example 4.

FIG. 4 is a graph showing fluctuations in the amount of mercury at the entrance and exit of a liquid-phase heavy metal adsorption tower in Example 4.

FIG. 5 is a view showing a gas-phase heavy metal continuous treatment apparatus used in Example 5.

Claims (7)

[Claims] 1. The method is selected from the group consisting of 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and ethylenediaminetetraacetic acid. A solution having a saturation concentration of 0.2% by mass or more of one or more chelating group-containing compounds is impregnated with one or more porous materials selected from the group consisting of activated carbon, zeolite, diatomaceous earth, natural sand, and ceramics. A heavy metal adsorbent obtained by binding the compound to a porous substance. 2. The amount of binding of the chelate-forming group-containing compound to the porous substance is 1 to 10% by mass of the porous substance.
The heavy metal adsorbent according to claim 1, wherein 3. The heavy metal adsorbent according to claim 1, wherein the particle size of the porous material is 4 to 40 mesh. 4. The heavy metal adsorbent according to claim 1, wherein the water content is 5 to 40% by mass. 5. The heavy metal adsorbent according to claim 1, which removes heavy metals or heavy metal compounds contained in the heavy metal-containing gas. 6. The heavy metal adsorbent according to claim 1, which removes heavy metal ions, heavy metals or heavy metal compounds contained in the heavy metal-containing solution. 7. A compound selected from the group consisting of 1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and ethylenediaminetetraacetic acid. A solution having a saturation concentration of 0.2% by mass or more of one or more chelating group-containing compounds is impregnated with the porous material to bind the compound to the porous material, and then the porous material is separated from the solution. And producing the heavy metal adsorbent.