JP4826573B2 - Hazardous substance elution inhibitor - Google Patents

Description

  In particular, the present invention relates to a hazardous substance elution preventing agent capable of preventing elution of harmful substances by solidifying the cement in a lump in addition to cement containing harmful substances such as chromium.

  In recent years, waste consisting of at least one of preheater or cement kiln for firing cement raw materials, inorganic sludge, and concrete resources, glass, sandy molten slag, silty coal ash, and recycled resources crushed from earthenware Is added to promote burning of the cement raw material to obtain cement, and the combustion fuel combustion product is part of the cement.

  When this cement raw material is fired, chromium contained in the cement raw material is oxidized and hexavalent chromium is contained in the cement. For example, when this cement is used for ground improvement, rainwater and river water In the process of infiltration into the underground, hexavalent chromium with a concentration exceeding the soil environmental standards may be eluted in this rainwater depending on conditions. And rainwater from which hexavalent chromium has been eluted becomes groundwater, and this groundwater may be ingested by humans as drinking water.

  For this reason, the Ministry of Construction Technical Proceedings No. 48 March 24, 2000, Minister of Construction Secretariat Technical Advisory Notice “Use of cement and cement-based solidifying agent for ground improvement and reuse of improvers” According to "About", it is obliged to conduct a hexavalent chromium elution test during ground improvement work, paving work, and temporary work. This dissolution test is stipulated in "Method for analyzing the amount of heavy metals in soil: Soil environmental standards, method fried in Environment Agency Notification No. 46 dated August 13, 1991". The hexavalent chromium concentration when quantifying hexavalent chromium based on the diphenylcarbazide spectrophotometric method (JIS K0102 65.2.1) is required to be 0.05 mg / L or less according to soil environmental standards. Has been.

In addition, even wastes to be burned fuel described above, including hexavalent chromium, regulating flaps Mi um, cyan, lead, arsenic, selenium, boron, mercury, in the Water Pollution Control Law, etc., such as alkyl mercury and PCB In the same way, there is a risk that harmful substances with a concentration exceeding the soil environmental standard may be eluted. In addition, the cement may be mixed with a cement-based solidifying agent in order to solidify, but this cement-based solidifying agent also contains hexavalent chromium and is contained in the cement-based solidifying agent. There is also a risk of elution of hexavalent chromium.

On the other hand, for example, a cement composition that suppresses an increase in the amount of harmful substances released by selecting wastes that do not contain harmful substances and putting them into a cement kiln has been developed and sold. In addition, as disclosed in Patent Document 1, a cement composition in which the elution amount of hexavalent chromium is reduced by mixing zeolite with cement or the like has been proposed.
However, the cement composition that suppresses the increase in the leaching amount of harmful substances by sorting this waste is not only expected to prevent the leaching amount of toxic substances from being below the environmental standard value, but is also currently being sold. However, since it is expensive due to waste sorting costs, it tends to be unusable at construction sites such as ground improvement and tunnel back-up where there is intense price competition.

  Furthermore, in recent years, environmental problems have become an important global issue. In addition to cement, for example, incinerated ash discharged after melting waste in a melting furnace, hexavalent chromium, etc. Therefore, it is also desired to prevent elution of harmful substances from these hazardous substance-containing materials.

JP 2007-176721 A

  Therefore, the present invention, by adding to a hazardous substance-containing material such as cement, solidifies this hazardous substance-containing material, can prevent the elution of harmful substances from the solidified product exceeding the environmental standard value, and relatively An object of the present invention is to provide an inexpensive and practically usable toxic substance elution inhibitor.

The present inventors have discovered that by adding to the cement or ash containing harmful substances harmful substances solute inhibitors were chelated iron salts to protein hydrolyzate, the cement or ash is solidified, from the solidified product The present inventors have found that the amount of harmful substances eluted can be significantly reduced, and have completed the present invention according to claims 1 to 4 below.

That is, the invention according to claim 1, cadmium is a toxic substance, cyanide, lead, hexavalent chromium, arsenic, selenium, boron, mercury, alkyl mercury, cement or ash containing more than one kind of PCB, the cement or ash in addition with solidifying agent to be flocculated, the cement or ash by solidifying by the solidifying agent, a hazardous substance elution preventive agent for preventing the elution of the toxic substances from the solidified product Thus, the divalent and / or trivalent iron salt is characterized by being chelate-bonded to the protein hydrolyzate.

Further, the invention according to claim 2 is a method for solidifying a cement containing one or more of toxic substances such as cadmium, cyan, lead, hexavalent chromium, arsenic, selenium, boron, mercury, alkylmercury and PCB in a lump. In addition to the cement, a harmful substance elution inhibitor for preventing the elution of the harmful substance from the solidified product, wherein a divalent and / or trivalent iron salt is chelated to the protein hydrolyzate. It is characterized by being.

  The invention according to claim 3 is characterized in that, in the harmful substance inhibitor according to claim 1 or 2, the protein hydrolyzate uses animal horns or hoofs as protein raw materials. is there.

  The invention according to claim 4 is the harmful substance elution preventing agent according to any one of claims 1 to 3, wherein the iron salt has an iron concentration of 0.2% by mass or more and 3.0% by mass. The protein hydrolyzate is chelate-bonded as follows.

According to the first to fourth aspects of the present invention, a harmful substance elution inhibitor obtained by chelating iron salt to a protein degradation product is added to cement or incineration ash , and the cement or incineration ash is used by itself or When solidified in a lump with a solidifying agent added as necessary, it is possible to prevent elution of harmful substances from the solidified product exceeding the standard value according to the environmental standards without changing the properties of the solidified product with the harmful substance elution inhibitor.

  At that time, if harmful substances such as hexavalent chromium are present in the solidified product, the divalent and / or trivalent iron salt acts as a reducing agent such as reducing hexavalent chromium to non-toxic trivalent chromium. Thus, it is presumed that the harmful substances such as hexavalent chromium are detoxified and the protein hydrolyzate adsorbs the harmful substances, thereby preventing the elution of the harmful substances.

In addition, when only a protein hydrolyzate in which an iron salt is not chelate-bonded is added to the cement or incinerated ash together with a solidifying agent, the amount of the protein hydrolyzate that is relatively expensive is increased. By making the protein hydrolyzate chelate-bonded with an iron salt, it becomes bulky, and by reducing the amount of protein hydrolyzate used, it is possible to provide a relatively inexpensive harmful substance elution inhibitor. At the same time, the toxic substance elution preventing agent can effectively prevent the toxic substance from eluting.

  In particular, for protein hydrolysates, animal horns or hoofs can be suitably used as protein raw materials, as in the invention described in claim 3.

  According to the invention described in claim 4, the harmful substance elution inhibitor is reliably harmful substances because the iron salt is chelated to the protein hydrolyzate so that the iron concentration is 0.2% by mass or more. Elution, and the iron salt is chelated to the protein hydrolyzate so that the iron salt concentration is 3.0% by mass or less. A decrease in the elution prevention effect of the substance can be prevented.

Hereinafter, the harmful substance elution preventing agent according to the present invention will be described.
The hazardous substance elution preventing agent of this embodiment is solidified in a lump by a solid agent or a hazardous substance-containing material itself that is added to the hazardous substance-containing material as necessary in addition to a harmful substance-containing material such as cement or incinerated ash. This significantly reduces the amount of harmful substances eluted from the solidified product.

Here, the hazardous substances, Kado Mi um, cyan, lead, hexavalent chromium, arsenic, selenium, boron, mercury, alkyl mercury, it is those including PCB, and subject to regulation, etc. Water Pollution Control Law Means the substance that has become.
Therefore, the hazardous substance-containing material includes cement and incinerated ash containing these harmful substances, and solidifies in a lump by a solidifying agent such as a cured resin or cement-based solidifying material or the hazardous substance-containing material itself. Means.

The hardened resin as the solidifying agent includes polyester resin, epoxy resin, furan resin, urethane resin, acrylic resin, thermoplastic resin emulsion, phenol resin, natural rubber, rubber latex, synthetic rubber such as silicone rubber and fluorine rubber. And one or more of water-insoluble polymer compounds such as water-resistant polyvinyl alcohol are used. In addition to these cured resins and cement-based solidifying materials, there are lime-based solidifying materials and gypsum as solid agents.
Examples of the hazardous substance-containing material that is solidified into a lump by the harmful substance-containing material itself include ordinary portland cement and blast furnace cement. When solidifying such ordinary portland cement and blast furnace cement, In some cases, a cement-based solidifying agent is added or not added.

In the harmful substance elution preventing agent of this embodiment added to the harmful substance-containing material, a divalent and / or trivalent iron salt is chelated to a protein hydrolyzate.
Here, protein is roughly classified into animal protein and vegetable protein, and protein hydrolyzate is added to these animal protein and vegetable protein with alkaline agents such as sodium hydroxide, calcium hydroxide and ammonia, Or it hydrolyzed by adding acidic agents, such as hydrochloric acid and acetic acid, or an enzyme.

Examples of the animal protein include horn, hoof, gelatin, blood, hair, salmon, egg white, fish meal, fish scale, and milk. Preferably, the animal horn and hoof are pulverized and used.
Plant proteins include beans such as soybeans and red beans, and wheat.

  And as an iron salt made to chelate bond with these protein hydrolysates, either a bivalent iron salt and a trivalent iron salt may be used, or both may be used. In addition, ferrous sulfate and ferrous chloride can be used as the divalent iron salt, and ferric sulfate, ferric chloride, iron oxide and iron nitrate are used as the trivalent iron salt. More preferably, ferrous sulfate and / or ferric sulfate is used as the iron salt.

This iron salt is chelate-bonded to the protein hydrolyzate so that the iron salt concentration is 0.2 mass% to 3.0 mass%, more preferably 0.4 mass% to 1.0 mass%.
It has been experimentally proved that when the iron concentration is less than 0.2% by mass, the action and effect as a harmful substance elution inhibitor for preventing the elution of harmful substances from the solidified product is weakened. This is because if the iron concentration exceeds 3.0% by mass, the protein hydrolyzate is denatured due to the influence of the iron salt, and the action and effect as a harmful substance elution inhibitor is weakened.

  Furthermore, the harmful substance elution preventing agent of the present embodiment includes a reducing agent, an antioxidant, a water-soluble inorganic metal salt, a surfactant, a water-soluble organic solvent, a water-soluble polymer, a dispersant, an antiseptic, as necessary. Agents are added. Among them, reducing agents detoxify harmful substances such as hexavalent chromium, antioxidants prevent poisoning due to oxidation of detoxified harmful substances, and these reducing agents and antioxidants are In particular, it contributes to prevention of toxic substance elution.

  This reducing agent includes sulfites, sodium thiosulfate, salts of lower oxides or lower oxygen acids such as sulfur dioxide and carbon monoxide, sulfur compounds such as sodium sulfide and ammonium sulfide, oxalic acid, formic acid, aldecides, saccharides, etc. These organic compounds, alkali metals, magnesium, tin chloride, and hydrogen compounds may be used alone or in combination.

  Antioxidants include sodium erythorbate, erythorbic acid, sodium ascorbate, ascorbic acid, sodium pyrosulfite, sulfur dioxide, or one or more of natural extracts such as tea extract and blueberry extract. May be used.

  Examples of water-soluble inorganic metal salts include sodium salts such as sodium sulfate and sodium chloride, potassium salts such as potassium sulfate and potassium chloride, magnesium salts such as magnesium sulfate and magnesium chloride, and calcium salts such as calcium sulfate and calcium chloride. One or two or more of them may be used.

  Surfactants include anionic surfactants such as alkyl ether sulfates and alpha olefin sulfonates, cationic surfactants such as monoalkyl ammonium chlorides and dialkyl ammonium chlorides, alkyl ether types, alkyl phenol types, and alkyl ester types. One type or two or more types of nonionic surfactants or amphoteric surfactants such as alanine type and imidazolinium betaine type may be used.

  Examples of water-soluble organic solvents include cellosolv solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve and isobutyl cellosol, carbitols such as ethyl carbitol and butyl carbitol, diols such as ethylene glycol and diethylene glycol, or ethylene oxide. One kind of polyoxyethylene lower alkyl ether having 3 to 10 added moles may be used, or two or more kinds may be used in combination. In addition, as the water-soluble organic solvent, cellosolve solvents and diols are preferably used, and more preferably, one of butyl cellosolve, isobutyl cellosolve, ethylene glycol and diethylene glycol is used, or two or more of them are used in combination. Is done.

  As water-soluble polymers, there are natural ones and synthetic ones. Examples of natural ones include polysaccharides made from seeds such as guar gum and tara gum, resins such as gum arabic and tragacanth, and sap. There are polysaccharides used as raw materials, polysaccharides made from seaweed such as alginic acid and carrageenan, fermentation product polysaccharides such as xanthan gum and curdlan, plant extracts such as pectin, and crustacean extracts such as chitin and chitosan. . In addition, examples of synthesized polymers include cellulose derivatives such as methyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol, sodium alginate, polyvinyl ether, sodium polyacrylate, and the like. Of these, one type is used, or two or more types are used in combination.

  As the dispersant, for example, one type of naphthalene sulfonic acid type, alkyl naphthalene sulfonic acid type, polycarboxylic acid type, polystyrene sulfonic acid type, alkyl amine type, alkyl phenol type, or the like is used, or two or more types are used in combination. Is done.

  When the above-mentioned harmful substance solute inhibitor is mixed with cement or the like, it may be used after being foamed in an aqueous solution and then mixed with cement. Alternatively, it may be diluted with water and mixed with cement.

  Below, the effect | action at the time of mixing the above-mentioned harmful | toxic substance elution inhibitor with cement is demonstrated.

  First, in a cement kiln that fires cement raw material, inorganic sludge and waste consisting of at least one of recycled materials obtained by grinding concrete glass, glass, sandy molten slag, silty coal ash, and pottery Supply as combustion fuel.

  Here, inorganic sludge refers to construction sludge discharged by a seal excavator or a boring machine, dredged sludge discharged when dredging a river or pond, and soil generated when crushed stone is washed in a quarry. Crushed stone sludge containing minutes.

Accordingly, the cement raw material is fired in the cement kiln to obtain cement, and the above-described inorganic sludge and waste are supplied as the combustion fuel, so these combustion fuels become a part of the cement.
As a result, when the above-mentioned harmful substance elution inhibitor is added to the obtained cement and, if necessary, cement-based solidifying material or gypsum as a solidifying agent is added to improve the ground, this cement-based solidifying material. Cement is solidified by gypsum or cement itself, and the elution of harmful substances such as hexavalent chromium from the solidified cement (solidified product) is prevented.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[Experimental example 1] Determination of elution amount of hexavalent chromium Hoofhorn powder hydrolyzate (keratin protein hydrolyzate: manufactured by Daiichi Kasei Sangyo Co., Ltd.) and ferrous sulfate / 7 hydrate (Hokou Kaken Kogyo) No. 1 in which ferrous sulfate and heptahydrate are chelate-bonded to the hoof horn powder hydrolyzate by mixing at a ratio shown in Table 1. 1 to 6 harmful substance elution inhibitors were obtained.

Next, 0.7 kg of Portland cement (manufactured by Taiheiyo Cement Co., Ltd.), 4.65 kg of crushed sewage sludge (manufactured by Mitomo Corporation) and 4.65 kg of desulfurized gypsum (manufactured by Mitomo Corporation) 70 mL No. No. 1 harmful substance elution inhibitor is added, and the solidified cement is solidified as No.1. One solidified product was obtained.
Similarly, no. In place of No. 1 harmful substance elution inhibitor, No. 2 to 6 toxic substance elution inhibitors were added to solidify each cement solidified product. It was set as 2-6 solidified material.
Furthermore, 0.7 kg of Portland cement (manufactured by Taiheiyo Cement Co., Ltd.), 4.65 kg of crushed sludge (dehydrated sludge made by Mitomo Co., Ltd.) and 4.65 kg of desulfurized gypsum (Mito Yu Co., Ltd.) No. 1) was added to the cement solidified product. 7 solidified product was obtained.

  These Nos. The elution test for hexavalent chromium of solidified materials 1 to 7 was performed in accordance with “Elution analysis method of heavy metals in soil: Soil environmental standards, method fried to Environment Agency Notification No. 46, August 13, 1991”, respectively. Then, hexavalent chromium was quantified based on diphenylcarbazide spectrophotometry (JIS K0102 65.2.1) as described later.

<Dissolution test>
No. Each of the 1 to 7 solidified products was air-dried, pulverized by removing wood chips, etc., and then powdered by passing through a sieve having 2 mm eyes. 1-7 powders were prepared.
Then, these No. To 1-7 powder, 10 mL of a solvent with pH = 5.8 to 6.3 added to pure water by adding hydrochloric acid to pure water is added and mixed, and shaken at room temperature and normal pressure (number of shakes). The mixture was shaken 200 times per minute at a shaking width of 4 to 5 cm for 6 hours, then left to stand for 10 to 30 minutes, and centrifuged at 3000 rpm for 20 minutes. As a result, the filtrate obtained by filtering the supernatant with a membrane filter (pore size 0.45 μm) It was set as the test liquid of 1-7.

<Quantitative test>: Diphenylcarbazide absorption photometry After taking each of the test solutions 1 to 7 in a 40 mL separatory funnel, 10 mL of 50% diluted sulfuric acid diluted with water having the same mass of concentrated sulfuric acid was added to each separatory funnel, and further potassium permanganate. After the solution was added dropwise and the liquid in the separating funnel was slightly colored, 5 mL of clopen (5% by mass concentration) and 10 mL of chloroform were further added to each separating funnel. Next, after the liquid in each separatory funnel is shaken for 30 seconds, it is allowed to stand and separated into two layers, and each liquid layer is divided into two different beakers A and B, and each beaker A, The liquid in B was neutralized with sodium hydroxide (4% by mass concentration).

Next, the solution in the beaker A from which the supernatant of the upper layer was collected was transferred to the volumetric flask A, and sulfuric acid having a dilution concentration of 10% was added to this solution.
On the other hand, by adding 3 mL of 10% diluted sulfuric acid and a small amount of 95% by weight ethanol to beaker B where the residual liquid in the lower layer was taken, the solution in beaker B was boiled to obtain hexavalent chromium. Was reduced to trivalent chromium, allowed to cool, and this solution was transferred to volumetric flask B.

  Next, with each volumetric flask A and B kept at about 15 ° C., 1 mL of diphenylcarbazide solution (1% by mass concentration) was added into these volumetric flasks A and B, and after shaking, a 50 mL line was added. Water was added until left for 5 minutes. Then, no. In order to quantify hexavalent chromium per 40 mL of the test solution in each measuring flask A for each of the test solutions 1 to 7, the absorbance at a wavelength of 540 nm was measured using the solution in the measuring flask B as a control solution, and the concentration was determined from the calibration curve. It was measured. And this density | concentration converted the test solution 40mL per 1L, and the result was shown in Table 2.

  As can be seen from Tables 1 and 2, No. No toxic inhibitor was added. The test solution for the solidified product No. 7 contains a large amount of hexavalent chromium of 0.7 mg / L. On the other hand, no. In the test solutions of solidified products 1 to 6, the content of hexavalent chromium was 0.3 mg / L or less.

  Furthermore, no. The test solution for the solidified product No. 1 has a hexavalent chromium content of 0.1 mg / L and an iron concentration of 4.0% by mass. The test solution of the solidified product of No. 6 has a hexavalent chromium content of 0.3 mg / L. 1 and no. The 6 test solutions all exceeded the soil environmental standard of 0.05 mg / L.

On the other hand, No. 1 prepared by mixing ferrous sulfate and heptahydrate with hoof powder hydrolyzate so that the iron concentration was 0.2% by mass to 3.0% by mass. The test solutions of solidified products 2 to 5 have a hexavalent chromium content of 0.01 mg / L. The solidified product of 2 to 5 was able to significantly reduce the elution of hexavalent chromium.
From this, it was found that the iron concentration of the harmful substance elution inhibitor is preferably 0.2% by mass to 3.0% by mass.

[Experimental example 2] Determination of elution amount of hexavalent chromium 4.5 kg of incinerated ash (Daiichi Kasei Sangyo Co., Ltd. (water content 85%)), hexavalent chromium (hexavalent chromium standard solution: concentration 1000 mg / L) : Wako Pure Chemical Industries, Ltd. (5 g) and Hicell OH (polyurethane resin: manufactured by Toho Chemical Industry Co., Ltd.) as a solidifying agent alone were added to solidify the solidified product. Eight solidified products were obtained.

  Similarly, incinerated ash (made by Daiichi Kasei Sangyo Co., Ltd. (water content ratio 85%)) 4.5 kg, hexavalent chromium (hexavalent chromium standard solution: concentration 1000 mg / L: Wako Pure Chemical Industries, Ltd.) No. 5) and Hicell OH (polyurethane resin: manufactured by Toho Chemical Industry Co., Ltd.) as a solidifying agent. No. 4 harmful substance elution inhibitor 70 mL was added, and the solidified product solidified was No. 1 Nine solidified products were obtained.

Next, in the same manner as in Experimental Example 1, the hexavalent chromium was quantified after the hexavalent chromium elution test.
The results are shown in Table 3.

  As can be seen from Experimental Example 2 described above, even when a resin-based solidifying agent other than a cement-based solidifying agent is used for solidification, by adding a harmful substance elution inhibitor, elution of hexavalent chromium from the solidified product. The amount can be significantly reduced.

[Experiment 3] Dissolution test Requested by the Southwest Environmental Research Institute Co., Ltd., an Okinawa-certified testing laboratory, the dissolution test of each hazardous substance shown in Table 4 for the solidified product 4 and the dissolution test. The toxic substances were quantified by the diphenylcarbazide absorptiometry. Table 4 shows the content of each harmful substance per 1 L of the test solution as a result. In Table 4, in the right column of the content of this hazardous substance, the method of dissolution test for each hazardous substance and the standard value for each hazardous substance (August 1991 Environment Agency Notification No. 46 (final revision) : Standard values (according to Ministry of the Environment Notification No. 16) in March 2001).
“Environmental Notification No. 64” shown in the column of the dissolution test method means Notification No. 64 of the Environment Agency in September 1974 (final revision: Ministry of the Environment Notification No. 37 in June 2001). This is an inspection method related to the wastewater standards set by the Minister of the Environment. Similarly, “announcement No. 59” means Notification No. 59 of the Environment Agency in December 1971 (final revision: Notification No. 123 of the Ministry of the Environment in November 2003). The “Prime Ministerial Ordinance No. 66” refers to the Prime Minister's Ordinance No. 66 in October 1972 (final revision: Prime Minister's Ordinance No. 94 in August 2000). It is a ministerial ordinance that stipulates the method for testing the amount of copper according to the designated requirements of the agricultural land and soil pollution control area.

  As can be seen from Table 4, even if we focus on harmful substances that are likely to be eluted from concrete materials, the respective contents are 0.01 mg / L for hexavalent chromium of 0.05 mg / L or less, and cadmium for cadmium. 0.001 mg / L with reference value 0.01 mg / L or less, cyan not detected, selenium 0.001 mg / L with reference value 0.01 mg / L or less, boron 0.01 mg / L with reference value 1 mg / L or less L. It was confirmed that other heavy metals also cleared the environmental standards, and it was confirmed that the toxic substance elution inhibitor prevented the elution of these toxic substances exceeding the environmental standard value.

Claims (4)

Solidifying agent that solidifies the cement or incinerated ash in a lump to cement or incinerated ash containing one or more of toxic substances such as cadmium, cyan, lead, hexavalent chromium, arsenic, selenium, boron, mercury, alkyl mercury, and PCB In addition, a toxic substance elution inhibitor that prevents the toxic substance from eluting from the solidified product by solidifying the cement or incinerated ash with the solidifying agent,
A toxic substance elution preventing agent, wherein a divalent and / or trivalent iron salt is chelate-bonded to a protein hydrolyzate. When solidifying cement containing one or more of toxic substances such as cadmium, cyanide, lead, hexavalent chromium, arsenic, selenium, boron, mercury, alkylmercury and PCB, in addition to the above cement, this solidified product A toxic substance elution inhibitor that prevents elution of the above toxic substances from
A toxic substance elution preventing agent, wherein a divalent and / or trivalent iron salt is chelate-bonded to a protein hydrolyzate.   The toxic substance inhibitor according to claim 1 or 2, wherein the protein hydrolyzate uses animal horns or hoofs as protein raw materials.   4. The iron salt according to claim 1, wherein the iron salt is chelate-bonded to the protein hydrolyzate so that the iron concentration is 0.2% by mass or more and 3.0% by mass or less. The harmful substance elution inhibitor according to any one of the above.