JP2000296389A - Method for removing heavy metals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively and cost-effectively elute and remove hazardous heavy metals included in a specific heavy metals-containing material by bringing a specific treating liquid into contact with this heavy metals-containing material into the treating liquid and makes the material disposable as it is or recycles the material as a fresh resource by utilizing the material as compost, etc., richly containing organic matter by fermentation. SOLUTION: This method for removing the heavy metals comprises the step of eluting the heavy metals included in the heavy metals-containing material by bringing the specific treating liquid into contact with the specific heavy metals-containing material or electrolyzing the heavy metals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively removing heavy metals from heavy metal-containing materials, and more particularly, to a method for effectively utilizing heavy metal-containing materials and causing harmful problems when disposed of. The present invention relates to a method for removing heavy metals effectively and easily and economically.

[0002]

2. Description of the Related Art Objects and substances existing in our living environment are often contaminated with harmful heavy metals and contain heavy metals. For example, sewage sludge, organic sludge such as human waste sludge or food factory sludge, soil, livestock manure, bottom mud,
Although seafood, animals, plants and the like can be used as resources, it is not easy to remove heavy metals from these heavy metal-containing substances.

[0003] Also, since rivers, soils, punktons, and the like existing in our living environment contain harmful heavy metals, fish, shellfish, animals, plants, and the like that inhabit there are above the standard value. It is known that it is often contaminated with heavy metals. For example, scallop uro (soft body) and oysters contain high concentrations of heavy metals, especially cadmium, and human kidney and liver also contain high concentrations of cadmium. It is known that cereals such as these also contain heavy metals such as cadmium, which can be harmful to human health.

In recent years, it has become necessary to utilize unused resources from the viewpoints of preserving the global environment and effectively utilizing and circulating resources. Developing a method of removing and detoxifying methane is an urgent and important task.

[0005] Further, apart from the viewpoint of effective use and recycling of resources, even when simply disposing of the heavy metal-containing material as described above, high concentrations of harmful heavy metals accumulate in waste disposal sites and the like. There is a problem that the environment is adversely affected again.

In order to solve such problems and problems,
There is a strong demand for the development of a method for effectively removing heavy metals from heavy metal-containing substances. Until now, organic sludge such as sewage sludge, human waste sludge, and food factory sludge, soil and sediment, and livestock manure have been developed. Various studies have been conducted mainly on a method for removing contained heavy metals.

[0007] For example, zinc from sewage sludge using sulfuric acid,
A method for removing copper, cadmium and the like (Environ.
Sci. Technol. , 9 (9), 849-855
(1975)), a method of removing cadmium, chromium, copper, iron, lead, zinc, and nickel from sewage sludge using sulfuric acid or hydrochloric acid (Water Res., 10, 1077).
-1081 (1976)). Recently, as a method for removing cadmium from scallop uro, a method of treating with 2 vol% sulfuric acid (sulfuric acid of about 3.6% by weight), and furthermore, by using electrolysis and sulfuric acid together, scallop uro is used. A method for removing cadmium from water has also been proposed.

In addition, the present inventors have developed and proposed a method for removing heavy metals contained in organic sludge such as sewage sludge, human waste sludge, and food factory sludge using an aqueous phosphoric acid solution. (Japanese Patent No. 2975571).

[0009]

As described above, many methods for removing heavy metals have been studied so far. However, since there are a variety of substances and substances containing heavy metals, a method that can be put to practical use is obtained. Therefore, it is necessary to develop more methods.

[0010] By the way, heavy metals existing in the environment are:
In general, these heavy metals are easily dissolved and recovered because they are adsorbed on biopolymers constituting animals, plants and fish and shellfish, or exist as inorganic salts and sulfides. It was not something.

[0011] In particular, when the heavy metal-containing substance is a fish, shellfish, animal or plant, etc., fish oil which prevents elution of the heavy metal,
Since oil components such as animal oils and vegetable oils are contained, they disturb the recovery and dissolution of heavy metals from heavy metal-containing substances with an aqueous phosphoric acid solution or the like, and the elution of heavy metals becomes even more difficult.

Therefore, recently, as a method for removing cadmium from scallop uro, for example, a method of treating with about 3.6% by weight of sulfuric acid has been proposed.

Although this method has succeeded in removing a considerable amount of cadmium from scallop uro, there are problems such as an increase in the size of the processing apparatus and a long processing time. In addition, this method has problems that the acidity is strong, a large amount of water is required to wash out sulfuric acid after the treatment, and the burden on post-treatment of wastewater containing a large amount of heavy metals is increased.

As described above, the inventor of the present invention has shown that phosphoric acid solutions have been extremely effective as a method for removing heavy metals contained in organic sludges such as sewage sludge, human waste sludge, and food factory sludge. Has been developed and proposed (Japanese Patent No. 2975571).

The present inventor has further studied the method for removing heavy metals using such a phosphoric acid solution. As a result, this method is not limited to organic sludges, but also includes a wide range of heavy metal-containing substances. That harmful heavy metals can be removed from water.

In particular, it has been found that by using this method for removing heavy metals, it is possible to effectively remove heavy metals from fish, shellfish, animals and plants, for which it has been conventionally difficult to remove heavy metals. Was.

In addition, regarding seafood, animals and plants, etc.,
By removing oil components such as fish oil, animal oil, vegetable oil, etc. which hinder the elution of heavy metals, heavy metals can be effectively removed even by using specific acids other than phosphoric acid aqueous solution, for example, 3% by weight or less sulfuric acid aqueous solution. I got the knowledge that I can do it.

The present invention has been completed based on these findings and removes heavy metals from heavy metal-containing substances by using a specific acid aqueous solution as a treatment liquid for treating heavy metal-containing substances. In particular, it is an object of the present invention to provide a method for removing heavy metals effectively, easily and economically from fish, shellfish, animals and plants, which has been conventionally determined to be difficult to remove. The purpose is to:

[0019]

In the method for removing heavy metals according to the present invention (hereinafter referred to as the first method of the present invention),
In order to achieve the above object, there is provided a method for removing heavy metals including a step of contacting a treatment liquid with a heavy metal-containing substance to elute heavy metals contained in the heavy metal-containing substance into the treatment liquid. The heavy metal-containing material is at least one selected from soil, sediment, livestock manure, fish and shellfish, animals or plants, and the treatment liquid is a phosphoric acid aqueous solution or other acids other than phosphoric acid; And / or at least one selected from aqueous phosphoric acid solutions containing an oxidizing agent.

The heavy metal-containing material to be subjected to the first method of the present invention includes known heavy metal-containing materials except organic sludge, and includes soil, bottom mud, livestock manure, At least one selected from seafood, animals and plants is included.

Therefore, the heavy metal-containing material to be subjected to the first method of the present invention includes a mixture of a plurality of types of heavy metal-containing materials.

The heavy metal-containing material to be treated by the first method of the present invention may be treated in a usual form, but preferably is finely cut or powdered to facilitate removal of heavy metals. It is preferable to use it in a state where it has been used.

In particular, when the heavy metal-containing substance is a seafood, an animal or a plant, etc., the heavy metal-containing substance contains oil components such as fish oil, animal oil, and vegetable oil which hinder the elution of the heavy metal. It is effective to remove oily components before processing.

In the first method of the present invention, heavy metals are removed from these heavy metal-containing materials. As the heavy metals, those which have a bad influence on the human body or cause environmental pollution are particularly used. Mainly mentioned.

Specifically, for example, metals such as aluminum, cadmium, chromium, copper, iron, mercury, manganese, molybdenum, nickel, lead, zinc and the like can be mentioned. In addition, arsenic, selenium Etc. can be similarly removed. In the first method of the present invention, not only the heavy metals described above but also these compounds are referred to as heavy metals.

In the first method of the present invention, the treatment liquid used in the method for removing heavy metals includes (1) an aqueous phosphoric acid solution, or (2) an acid other than phosphoric acid and / or
Alternatively, a phosphoric acid aqueous solution containing an oxidizing agent may be used.

Here, phosphoric acid means condensed phosphoric acid such as orthophosphoric acid, metaphosphoric acid or polyphosphoric acid, phosphorous acid,
The term includes hypophosphorous acid, diphosphorus pentoxide and the like.

The concentration of the aqueous solution of phosphoric acid in the first method of the present invention is not particularly limited and may be appropriately selected depending on the content of heavy metals and the type of metal to be removed. % Or less, more preferably 0.01 to 8%
A concentration in the range of 5% by weight is preferred.

When the concentration of the phosphoric acid aqueous solution is 85% by weight or more, the effect of removing heavy metals is limited, the acidity is strong, post-treatment is difficult, and the cost is increased. When the concentration of the aqueous phosphoric acid solution is 0.01% by weight or less, the removal rate of heavy metals such as mercury, chromium, and lead becomes low, which is not preferable.

Specifically, for example, when removing metals contained in soil and the like, a phosphoric acid concentration of 10% by weight or more is preferable. When removing metals contained in fish and shellfish, etc. Is preferably a phosphoric acid concentration of 20% by weight or less.

In the first method of the present invention, examples of the oxidizing agent contained in the treatment liquid include hydrogen peroxide, hypochlorous acid, potassium hypochlorite, sodium hypochlorite, sodium perborate and the like. No. In this case, by blowing air or introducing ozone by aeration, the oxidation effect can be improved, and the elution effect of heavy metals can be improved.

Further, the oxidizing agent is added to the processing solution in an amount of 0.0.
It is preferable that the oxidizing agent is blended in the treatment liquid at a ratio of from 0.01 to 20% by weight, preferably from 0.01 to 5% by weight. If the amount of the oxidizing agent is less than 0.001% by weight, the effect is poor.
There is no point in mixing, and if it exceeds 20% by weight, the effect is limited, the post-treatment becomes difficult, and the cost becomes wasteful.

Furthermore, by subjecting the treatment liquid to stirring, aeration treatment, ultrasonic treatment, homogenizer treatment, etc., the reaction promoting effect and the oxidation effect can be improved.

Acids other than phosphoric acid contained in the treatment liquid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and boric acid, formic acid, acetic acid, oxalic acid, citric acid, maleic acid, fumaric acid, pyruvic acid, and succinic acid. And organic acids such as tartaric acid, phthalic acid and the like, which can be contained in an optional ratio to the aqueous phosphoric acid solution.

In the method for removing heavy metals according to the present invention (hereinafter, referred to as the second method of the present invention), in order to achieve the above object, a treatment liquid is brought into contact with the heavy metal-containing material to remove the heavy metal-containing material. A method for removing heavy metals, comprising a step of eluting contained heavy metals into the treatment solution, wherein the heavy metal-containing material is at least one selected from fish and shellfish, animals and plants, The treatment liquid is at least one selected from aqueous solutions of organic acids, hydrochloric acid, nitric acid, boric acid or sulfuric acid (3% by weight or less).

That is, in the second method of the present invention, the heavy metal-containing substance is intended for fish, shellfish, animals, and plants. In this case, (3) an organic acid, hydrochloric acid, or nitric acid is used as a treatment liquid. , Boric acid or sulfuric acid (3% by weight or less).

Here, examples of the organic acid aqueous solution include aqueous solutions of formic acid, acetic acid, oxalic acid, citric acid, maleic acid, fumaric acid, pyruvic acid, succinic acid, tartaric acid, phthalic acid and the like.

In the second method of the present invention, the concentration of the aqueous acid solution is the same as that of the aqueous sulfuric acid solution (3% by weight or less).
There is no particular limitation, and any concentration can be used. The concentration is appropriately selected and used depending on the heavy metal-containing material and the type of metal to be removed, but generally 10% by weight or less is preferable. The concentration in the range of 0.01 to 10% by weight is preferable. When the concentration of the aqueous acid solution is less than 0.01% by weight, the removal rate of heavy metals such as mercury, chromium, and lead becomes low. On the other hand, if it exceeds 10% by weight, considerable care must be taken in handling, and not only waste is increased, but also the acidity becomes too high, making it difficult to handle and treat the wastewater after treatment. It is not preferable because there is a problem.

When sulfuric acid is used, if the concentration of sulfuric acid exceeds 3% by weight, excess sulfuric acid is present, and even if the treatment liquid is brought into direct contact with the adsorbent, the adsorption of heavy metals becomes insufficient. Also, it is not preferable because the operation of removing sulfuric acid from the heavy metal-containing material after the treatment and the post-treatment of the treatment liquid occur.

Other conditions in the second method of the present invention are the same as those in the first method of the present invention.

As described above, in the first and second methods of the present invention, as the treatment liquid, (1) a phosphoric acid aqueous solution, (2) a phosphoric acid aqueous solution containing an acid other than phosphoric acid and / or an oxidizing agent, Alternatively, (3) at least one selected from aqueous solutions of organic acids, hydrochloric acid, nitric acid, boric acid, and sulfuric acid (3% by weight or less) can be used, and among them, the treatment liquids of (1) and (2) above Is preferred.

The reason for this is that phosphoric acids have a higher biological affinity than other acids, and heavy metals accumulated in living organisms can be effectively eluted by biosorption (biological adsorption). Because it can be.

The aqueous phosphoric acid solution is generally a weak acid and has a low risk. In addition, when heavy metals eluted in the treatment liquid are removed by using an adsorbent described later, measures such as pH adjustment are taken. This is because handling is extremely simple because it is not necessary.

In the first and second methods of the present invention, the heavy metals contained in the heavy metals are eluted into the processing solution by bringing the processing solution into contact with the heavy metal-containing material. There are no particular restrictions on the use amount, treatment temperature, and treatment time, and they are appropriately selected and used depending on the type of heavy metal-containing substance and the amount and type of heavy metal contained.

Generally, heavy metal-containing substances (dry state)
It is preferable to use about 1 to 10 times the amount of the treatment liquid, especially 1 to 5 times the amount of the mass 1 of the above.

In the first and second methods of the present invention, the temperature during the treatment can be selected from any temperature range from room temperature to the boiling point of the extract.
About 5 ° C. is preferable.

Further, the processing time is about 10 minutes to 1 day, and heavy metals can be easily removed.

In the first and second methods of the present invention, in order to achieve the above object, as described above, the treating solution in which the heavy metals in the heavy metal-containing substance are eluted is brought into contact with the adsorbent to thereby achieve the object. It is preferable to further include a step of adsorbing and removing heavy metals in the treatment liquid by an adsorbent, and to use them together.

With this configuration, heavy metals can be easily adsorbed and removed from the processing solution by the adsorbent. Therefore, heavy metals are removed from the processing solution containing heavy metals, and the processing solution is recycled and reused (reused). ), And it is possible to obtain a heavy metal-containing material in which the concentration of heavy metals is significantly reduced, and reuse the heavy metal-containing material after treatment without performing post-treatment such as washing. This is because it becomes possible.

In the method for removing heavy metals according to the present invention (hereinafter, referred to as the third method of the present invention), in order to achieve the above object, a treatment liquid is brought into contact with the heavy metal-containing material to remove the heavy metal-containing material. A method for removing heavy metals, which comprises a step of eluting contained heavy metals into the treatment solution and performing electrolysis to precipitate heavy metals in the treatment solution on a cathode. The content is sewage sludge, human waste sludge, food factory sludge, soil, livestock manure, bottom mud,
At least one selected from seafood, animals, plants, etc.
And wherein the treatment liquid is at least one selected from an aqueous phosphoric acid solution and an aqueous phosphoric acid solution containing an acid other than phosphoric acid and / or an oxidizing agent.

The third method of the present invention is, so to speak, an electrolysis (electrolysis) method. As this method, a known electrolysis method can be used. Specifically, a carbon electrode is used as an anode, a platinum electrode, a stainless steel plate electrode, or the like is used as a cathode, and a single or multi-tank plastic container, a glass container, or the like is used as an electrolysis tank.

The conditions for the electrolysis are as follows:
In the range of 10 to 10 volts and the current in the range of 100 mA to 5 A
The electrolysis may be performed for 10 hours to 5 days.

Further, in the third method of the present invention, it is desirable that the heavy metal-containing material and the treatment liquid are treated with an ultrasonic wave, a homogenizer or the like to facilitate dissolution and movement of the metal.
The heavy metals removed from the heavy metal-containing material are deposited and removed on the cathode as hydroxides or metallic substances, and the removal rate of the heavy metals is improved. In the electrolysis method, hydrogen peroxide is generated and copper can be easily removed.

In addition, in the third method of the present invention, the treatment liquid after electrolysis can be recycled and reused after separating heavy metal-containing substances.

In the third method of the present invention, after the electrolysis is performed, if necessary, the treatment liquid is brought into contact with an adsorbent to adsorb heavy metals remaining in the treatment liquid to the adsorbent. Thus, the heavy metals may be removed.

In the first to third methods of the present invention, as the heavy metal adsorbent, any known adsorbent capable of adsorbing heavy metals can be used. Specifically, for example, a strongly acidic cation Exchange resin, weak acidic cation exchange resin,
Cation exchange membranes and the like can be mentioned.

[0057]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition,
In the following examples, all percentages are by weight unless otherwise specified.

Example 1 Paddy soil was collected, and the content of heavy metals contained in the soil was measured by the aqua regia boiling method. [Unit: ppm (dry weight): As, 125; Cd,
4.51, Cr, 24.7; Cu, 64.3; Fe, 9
600; Hg, 35.8; Ni, 7.18; Pb, 9
0.4; Zn, 332]

To 10.0 g of this soil, an aqueous phosphoric acid solution of various concentrations (20%, 8%) containing 2% hydrogen peroxide was added.
After stirring for 1 hour at room temperature, the soil was filtered, and the concentration of heavy metals contained in the aqueous phosphoric acid solution was determined by ICP.
(Inductively Coupled Plas
(Ma Spectrometry) method, and the removal rate was calculated. Table 1 shows the results.

[0060]

[Table 1]

When the soil was treated with a 20% aqueous solution of phosphoric acid containing no hydrogen peroxide under the same conditions, the removal rate of copper was 7%. Furthermore, when the soil was treated at 90 ° C. using a 20% aqueous phosphoric acid solution containing 2% hydrogen peroxide, the removal rate of copper was 55%.

Example 2 The soil of a field was collected, and the content of heavy metals contained in the soil was measured by the aqua regia boiling method. [Unit: ppm (dry weight): As, 168; Cd,
5.36; Cr, 27.6; Cu, 115; Fe, 11
600; Hg, 44.4; Ni, 6.42; Pb, 12
0; Zn, 378]

To 10.0 g of this soil, an aqueous solution of phosphoric acid of various concentrations (40%, 20%) containing 2% hydrogen peroxide was added.
After adding 0 ml and stirring at room temperature for 1 hour, the soil was filtered, the concentration of heavy metals contained in the aqueous phosphoric acid solution was measured by the ICP method, and the removal rate was calculated. Table 2 shows the results.

[0064]

[Table 2] A Cr removal rate of 123% indicates that a measured value 1.23 times the actual measured value (standard value) of the Cr by the aqua regia boiling method was obtained.

When the treatment was performed at 60 ° C. using a 20% phosphoric acid aqueous solution containing 2% hydrogen peroxide, the removal rate of copper was 58%. Furthermore, the removal rate of copper was 32% when ultrasonic treatment was performed using an 8% phosphoric acid aqueous solution while aeration at room temperature.

Example 3 30 ml of a 20% phosphoric acid aqueous solution containing 2% hydrogen peroxide was added to 10.0 g of commercially available fermented beef dung (dried product), and the mixture was added at room temperature.
After stirring for an hour, the cow dung was collected by filtration, and the content of heavy metals in the aqueous phosphoric acid solution was measured using the ICP method.

In this case, the content of heavy metals in the aqueous phosphoric acid solution was as follows. [(Unit: ppm): As, 22.9; Cd, 1.0;
Cr, 7.6; Cu, 0.67; Fe, 365; Ni,
1.41; Pb, 12.6; Zn, 65.2]

Example 4 2% in 10.0 g of bottom mud (dried product) at the mouth of the Katsuura River in Tokushima City
100 ml of a 40% phosphoric acid aqueous solution containing hydrogen peroxide was added, and the mixture was stirred at 50 ° C. for 3 hours. Next, the bottom mud was filtered, and the content of heavy metals in the aqueous phosphoric acid solution was measured by the ICP method. The measured values were as follows. [(Unit: ppm): Cr, 1.83; Cu, 3.8
5; Zn, 17.9]

Reference Example The content of cadmium contained in scallop uro was determined by decomposing a sample using the aqua regia boiling method and using the ICP method. That is, 10 g of scallop uro (midgut gland, washed with water to remove oil, solid content 34%) is placed in a 200 ml beaker, 60 ml of aqua regia is added, and the mixture is boiled down to be contained in the decomposition solution. The content of heavy metals was measured using the ICP method. The average content of heavy metals contained in the scallop uro was as follows. [(Unit: ppm dry weight): Cd, 98.4 ppm;
Zn, 121.1 ppm; Cu, 36.9 ppm]

Example 5 Various concentrations (W / W%) were added to 20 g of scallop uro (midgut gland).
Of phosphoric acid aqueous solution was added and immersed for 24 hours.
Next, the cadmium concentration in the aqueous phosphoric acid solution after 24 hours was measured by the ICP method, and the amount of cadmium removed from the urine [unit: mg / kg (ppm) · uro dry weight] was measured. [Eluted (removed) amount in phosphoric acid aqueous solution]: 5% phosphoric acid, 83.0 ppm; 10% phosphoric acid, 105 ppm;
20% phosphoric acid, 82.1 ppm; 40% phosphoric acid, 49.
5 ppm.

Example 6 Scallop uro (middle gut, washed with water to remove oil)
To 20 g, 100 ml of an aqueous acid solution of various concentrations (W / W%) was added and immersed for 24 hours. Next, the concentration of heavy metals in the aqueous acid solution after 24 hours was measured by ICP method, and the amount of heavy metals eluted (removed) from uro [mg / kg (pp
m) · Uro dry weight] was measured. [Eluted (removed) amount in aqueous acid solution]: 5% phosphoric acid, Cd
(107 ppm), Zn (137 ppm); 10% phosphoric acid, Cd (100 ppm), Zn (127 ppm); 2
0% phosphoric acid, Cd (64.4 ppm), Zn (100 p
pm); 40% phosphoric acid, Cd (48.0 ppm), Zn
(65.5 ppm); 2% sulfuric acid, Cd (93.6 pp)
m), Zn (130 ppm).

Example 7 200 g of scallop uro (midgut gland, cut to a width of 0.3 to 0.5 mm, solid content 32%) was centrifugally dehydrated to obtain 137 g of uro. 100 ml of phosphoric acid aqueous solutions of various concentrations were added to 13.7 g of the urethane and immersed for 24 hours. Next, after separating the phosphoric acid aqueous solution by decantation, the uro was centrifugally dehydrated, and 100 ml of water was added to the uro and left for 3 hours. Thereafter, the aqueous layer was separated by decantation, and the uro was centrifugally dehydrated, followed by boiling in aqua regia. And
The cadmium content and the cadmium removal rate in the phosphoric acid aqueous solution, the washing solution, and the urethane after the treatment were measured using the ICP method. Table 3 shows the measurement results.

[0073]

[Table 3]

The contents of copper and zinc when a 0.3% phosphoric acid aqueous solution was used were as follows. Copper: [Aqueous solution of phosphoric acid (6.0 ppm), washing solution (2.4
ppm), Uro after treatment (26.5 ppm, removal rate of copper 2)
4%)] Zinc: [Aqueous solution of phosphoric acid (112 ppm), washing solution (1
0.2 ppm), Uro after treatment (5.4 ppm, removal rate of zinc 96%)]

Example 8 20 g of scallop uro (midgut gland, cut to a width of 0.3-0.5 mm) was centrifugally dehydrated to obtain 14.4 g of uro. 100 ml of a 2.5% phosphoric acid aqueous solution was added to
Stirred at 0 rpm. 10 ml of the phosphoric acid aqueous solution was collected over time, and the cadmium concentration was measured by the ICP method. The results were as follows. 1 hour (5.465 ppm), 2 hours (6.329 pp)
m), 4 hours (6.944 ppm), 6 hours (7.05 ppm)
7 ppm), 24 hours (7.269 ppm).

The urine after the reaction is centrifugally dehydrated, and 100 ml of water
Was added and left for 3 hours. The aqueous layer was separated, and the uro was centrifugally dehydrated and then decomposed by the aqua regia boiling method. The cadmium content of the aqueous layer and the treated uro was 10 ppm and 1.
It was 5 ppm (cadmium removal rate 99%).

Example 9 100 ml of a 10% phosphoric acid aqueous solution was added to 20 g of scallop uro (midgut gland, 0.3-0.5 mm width cut),
After heating at 90 ° C. for 30 minutes, it was allowed to cool. The amount of elution (removal) of heavy metals from uro [mg / kg (ppm) / dry weight] was as follows. [Cd, 91.2 ppm; Cu, 30.2 ppm]

Example 10 100 ml of a 10% phosphoric acid aqueous solution was added to 20 g of scallop uro (midgut gland, 0.3-0.5 mm width cut).
The mixture was stirred at 100 rpm for 4 hours. After the treated product was subjected to centrifugal filtration, the uro was washed with 600 ml of water, and the uro was centrifugally dehydrated. Removal amount of heavy metals from phosphoric acid aqueous solution [mg / kg
(Ppm) · Uro dry weight], and the content and elution (removal) rate% of heavy metals in the treated uro were as follows. Phosphoric acid aqueous solution: [Cd, 60.3 ppm; Cu, 29.
2 ppm] Uro after treatment: [Cd, 0.39 ppm (removal rate 99
%); Cu, 8.9 ppm (removal rate 70%)]

Example 11 Scallop uro (midgut gland, chopped) 10% in 20 g
100 ml of a phosphoric acid aqueous solution was added and shaken for 30 minutes. Next, the urine was collected by filtration and washed repeatedly with a small amount of water (water amount: 120 ml). Furthermore, after centrifugally dewatering the uro, aqua regia boiling treatment was performed. The amount of elution (removal) of heavy metals into the phosphoric acid aqueous solution [mg / kg (ppm) / uro dry weight] is 61.0 ppm, and the cadmium content in the treated ururo is 1.95 ppm (removal rate 97%). )Met.

Example 12 300 ml of a 10% aqueous solution of phosphoric acid was added to 100 g of the soft part of the scallops (uro), and the mixture was stirred at room temperature for 1 hour. The cadmium content in the uro decreased from 65 mg / kg (ppm) dry weight before the treatment to 0.85 mg / kg (ppm) dry weight after the treatment.

Example 13 200 ml of a 2.5% phosphoric acid aqueous solution was added to 13.7 g of scallop uro (midgut gland, cut to a width of 0.3 to 0.5 mm, solid content 47%) for 24 hours Dipped. Next, after separating the aqueous phosphoric acid solution by decantation, the uro was centrifugally dehydrated. The amount of elution (removal) of heavy metals into the phosphoric acid aqueous solution [mg / kg (ppm) · uro dry weight] and the cadmium content in the treated uro are 75%, respectively.
ppm and 3.4 ppm (96% removal rate).

Example 14 To 20 g of scallop uro (midgut gland, cut to a width of 0.3 to 0.5 mm), 99 ml of a 10% phosphoric acid aqueous solution and 1 ml of a 30% hydrogen peroxide solution were added, and the mixture was added at 100 rpm for 4 hours. Stirred. The amount of elution (removal) of heavy metals into this phosphoric acid aqueous solution [mg / kg (ppm) / uro dry weight] was as follows. [Cd, 95.5 ppm; Cu, 29.7 ppm]

Example 15 Various acid aqueous solutions were added to 6.7 g of scallop uro (midgut gland, cut to a width of 0.3 to 0.5 mm, solid content 50%).
0 ml was added and immersed for 24 hours. Then, each of the acid aqueous solutions was separated by decantation, and then the uro was centrifugally dehydrated, and 50 ml of water was added to the uro and left for 1 hour.

The aqueous layer was separated by decantation, and the uro was centrifugally dehydrated, followed by boiling in aqua regia. Table 4 shows the results of measuring the cadmium content of each of the aqueous acid solution, the washing solution, and the treated urethane using the ICP method.

[0085]

[Table 4]

Example 16 Various acid aqueous solutions were added to 10 g of scallop uro (midgut gland, cut to 0.3 to 0.5 mm width, solid content 50%).
ml and immersed for 24 hours. Each of the acid aqueous solutions was separated by decantation, and uro was centrifugally dehydrated, followed by boiling in aqua regia. Table 5 shows the results of measurement of the cadmium content in the treatment solution and the decomposition solution using the ICP method.

[0087]

[Table 5]

Example 17 To 50 g of scallop uro (midgut, cut to 0.3 to 0.5 mm width, solid content: 44%), 500 ml of a 1% phosphoric acid aqueous solution was added and immersed for 12 hours. Uro was centrifugally dehydrated. Next, 2.5 g of powdered activated carbon was added to the treated liquid, followed by filtration. The filtrate was passed through a cation exchange resin (Amberlite IR-120B) column to recover a phosphoric acid aqueous solution. The cadmium content in the recovered phosphoric acid aqueous solution is 0.
ppm.

The recovered phosphoric acid aqueous solution was added to the urine again and 12
After soaking for hours, the uro was centrifugally dehydrated. The cadmium content of the obtained uro was 0.38 ppm (as solid matter).

Example 18 100 ml of a 2% phosphoric acid aqueous solution was added to 13.4 g of scallop uro (midgut, cut to 0.3 to 0.5 mm width, solid content 44%), and the mixture was treated with a cation exchange resin. (Amberlite IR-120B) (5 ml) was added and left to stand for 40 hours. Next, the uro was fractionated and centrifugally dehydrated. The cadmium content of the obtained uro was 2.3 ppm (in terms of solids).

After the treatment mixture was stirred at 100 rpm for 24 hours, the uro was centrifugally dehydrated. The cadmium content of the obtained uro was 0.13 ppm.

Example 19 To 8.0 g of crested squid liver (solid content: 44%) was added 40 ml of a 1% phosphoric acid aqueous solution, mixed, left to stand for 2 hours, and then the phosphoric acid aqueous solution was filtered off. The content (removal rate%) of heavy metals in the phosphoric acid aqueous solution was as follows. [Cd, 3.90 ppm (99%); Zn, 75.5p
pm (95%); Cu, 196 ppm (58%)]

Example 20 50 ml of a 1% phosphoric acid aqueous solution was added to 10 g of the oyster guts (solid content: 20%), and the mixture was immersed for 24 hours, and the phosphoric acid aqueous solution was collected by filtration. The content (removal rate%) of heavy metals in the phosphoric acid aqueous solution was as follows. [Cd, 1.60 ppm (99%); Zn, 972 pp
m (80%); Cu, 78 ppm (58%)]

Example 21 50 ml of a 5% phosphoric acid aqueous solution was added to 10 g of beef liver,
After immersion for 24 hours, the aqueous phosphoric acid solution was collected by filtration. The content of heavy metals in the aqueous phosphoric acid solution was as follows. [Cd, 0.0082 ppm; Zn, 12.1 pp
m; Cu, 7.2 ppm]

Example 22 To 10.0 g of Canadian peat moss, 30 ml of a 20% phosphoric acid aqueous solution containing 2% hydrogen peroxide was added and immersed for 3 hours.
The elution (removal) amounts of the heavy metals were as follows. [As, 84.4 ppm; Cd, 2.36 ppm; C
r, 30.2 ppm; Cu, 1.17 ppm; Fe, 3
33 ppm, Ni, 5.98 ppm; Pb, 45.9 p
pm; Zn, 9.71 ppm]

Example 23 To 10 g of brown rice was added 50 ml of a 5% aqueous solution of phosphoric acid, and the resultant was immersed for 24 hours. The content (removal) of heavy metals in this phosphoric acid aqueous solution was as follows. [Cd, 0.0023 ppm; Zn, 2.47 ppm;
Cu, 0.20 ppm]

Example 24 30 g of an 8% phosphoric acid aqueous solution was added to 10.0 g of the sludge dewatered cake.
, And the mixture is mixed by ultrasonic waves, placed in a cylindrical filter paper, and placed in a beaker containing an 8% phosphoric acid aqueous solution. Put a carbon anode in the sludge layer and a platinum electrode in the 8% phosphoric acid aqueous solution layer.
A current of 00 mA was passed for three days.

As a result, the content of copper contained in the sludge was 3
Reduced from 73 ppm to 44.8 ppm (removal rate 88
%). The amount of cadmium is from 2.29 ppm to 0.1.
It was reduced to 6 ppm (93% removal rate).

Example 25 100 g of scallop soft body (uro) was placed in a beaker.
300m of 10% phosphoric acid aqueous solution containing 0.1% hydrogen peroxide
After adding 200 ml of 1% and 2% sulfuric acid and stirring, a carbon anode and a stainless steel cathode were put in, electrolysis was performed at a voltage of 3 V and a current of 1 A for 1 day, and then the urine was collected by filtration and washed with water.

The cadmium content of this uro is:
The dry weight of 65 mg / kg (ppm) before the treatment decreased to 0.65 mg / kg (ppm) after the treatment.

[0101]

The method for removing heavy metals according to the present invention has the above-mentioned structure, that is, by contacting a specific processing solution with a specific heavy metal-containing substance, the harmful substance contained in the heavy metal-containing substance is removed. It has the effect that the heavy metals can be effectively eluted and removed from the processing solution.

According to the method for removing heavy metals of the present invention,
As described above, harmful heavy metals can be effectively and economically removed from specific heavy metal-containing materials, which has been difficult to remove. The effect can be achieved on a scale.

Furthermore, the heavy metal-containing material from which heavy metals have been removed by the method for removing heavy metals of the present invention has no risk of environmental pollution. Therefore, it is disposed of as it is or is fermented and used as compost rich in organic matter. This has the effect that it can be reused as a new resource.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 11/00 F term (Reference) 4D004 AA02 AA04 AB03 CA04 CA12 CA15 CA34 CA41 CA44 CA47 CC12 CC20 DA03 DA10 4D024 AA09 AA10 AB16 BA17 BB01 BC01 DB01 DB09 DB10 DB20 DB23 4D059 AA01 AA08 AA09 AA11 BC02 BH04 BH08 BK11 BK16 BK21 BK22 DA11 DA31 DA32 DA33 DA39 DA43 DA44 DA45 DA47 DB08 DB11 DB26 4D061 DA08 DA10 DB18 DC20 EA05 EB05 FA30 EB05 EB05 FA30 FA11 FA16 GC12 GC14 GC15

Claims (4)

[Claims] 1. A method for removing heavy metals, comprising: contacting a treatment liquid with a heavy metal-containing substance to elute heavy metals contained in the heavy metal-containing substance into the treatment liquid. And at least one selected from soil, sediment, livestock manure, fish and shellfish, and animals and plants, wherein the treatment solution is a phosphoric acid aqueous solution or an acid other than phosphoric acid and / or an oxidizing agent. A method for removing heavy metals, wherein the method is at least one selected from aqueous phosphoric acid solutions. 2. A method for removing heavy metals, comprising: contacting a treatment liquid with a heavy metal-containing substance to elute heavy metals contained in the heavy metal-containing substance into the treatment liquid; And the treatment liquid is at least one selected from an aqueous solution of an organic acid, hydrochloric acid, nitric acid, boric acid or sulfuric acid (3% by weight or less). A method for removing heavy metals. 3. The method according to claim 1, further comprising the step of: bringing a treatment liquid eluted from the heavy metals contained in the heavy metal-containing substance into contact with an adsorbent to adsorb and remove the heavy metals in the treatment liquid with the adsorbent. Item 3. The method for removing heavy metals according to Item 1 or 2. 4. A process liquid is brought into contact with a heavy metal-containing substance to elute heavy metals contained in the heavy metal-containing substance into the processing liquid, and electrolysis is performed to remove heavy metals in the processing liquid. A method for removing heavy metals, comprising a step of depositing on a cathode, wherein the heavy metal-containing material is at least one selected from organic sludge, soil, sediment, livestock manure, fish and shellfish, and animals and plants.
A method for removing heavy metals, wherein the treatment liquid is at least one selected from an aqueous phosphoric acid solution and an aqueous phosphoric acid solution containing an acid other than phosphoric acid and / or an oxidizing agent. .