JP2011088077A - Clarifying material for organic halogen compound and clarification method using clarifying material, recycling method of the clarifying material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clarifying material for an organic halogen compound that excels in dissolving speed of underground water contaminated by the organic halogen compound and that has reduced cost, and to provide a clarification method using the clarifying material and a recycling method of the clarifying material. <P>SOLUTION: The clarifying material for the organic halogen compound is a mixture of first particles composed of metal carrying particles in which a platinum group element or nickel is carried on a carrier, with second particles composed of iron powder, or metal powder in which the surface of the iron powder is coated with metal more precious than iron, or metal powder comprising iron alloy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic halogen compound purification material capable of rapidly purifying groundwater contaminated with an organic halogen compound, a purification method using the purification material, and a recycling method of the purification material.

Organohalogen compounds have been widely used in the semiconductor manufacturing industry, metal processing industry, cleaning industry, etc. as degreasing solvents with excellent dissolving power, but contamination of soil and groundwater by organohalogen compounds after use has become serious. Yes.
Methods for detoxifying organohalogen compounds include removing contaminated soil from its original location, treating soil in situ or groundwater in which organochlorine compounds are dissolved, decomposing organohalogen compounds, and contaminated soil A method for purifying groundwater flowing out from contaminated soil in the surrounding area has been proposed.

  Among these methods, the method of purifying contaminated soil in-situ involves biodegrading with anaerobic microorganisms, bringing iron powder into contact with moisture, and reducing organic halogen compounds with hydrogen generated when iron powder is oxidized. Then, there is a method of decomposition (hereinafter referred to as iron powder method). Among these methods, the iron powder method is currently becoming mainstream because it has excellent reliability of effects and is suitable for treating a large amount of contaminated soil such as a factory site.

As a technique related to such an iron powder method, there is an invention of “noble metal-supported metal iron particles for soil / groundwater purification treatment” described in Patent Document 1.
The “noble metal-supported metal iron particles for soil / groundwater purification treatment” described in Patent Document 1 are “noble metal-supported metal iron particles used for the purification treatment of soil / groundwater contaminated with organohalogen compounds,” The supported metallic iron particles have a mean particle size of 1.0 to 100 μm and a powder pH of 7 to 11 and are composed of metallic iron particles and one or more kinds of noble metals selected from ruthenium, rhodium and palladium. It is a particle | grain, Comprising: The content of a noble metal is 0.01 to 0.5 weight% ".

  Moreover, there exists invention of the detoxification processing agent for to-be-processed objects disclosed by patent document 2 as another technique regarding an iron powder method. The invention disclosed in Patent Document 2 is “contaminated with an organic halogen compound composed of an Fe—Ni alloy obtained by alloying a mixture of 100 parts by weight of Fe powder and 0.01 to 2 parts by weight of Ni powder by a mechanical alloying method. Detoxification treatment agent for processed material "(refer to Patent Document 2 and Claim 1).

JP 2008-194542 A JP 2004-57881 A

The invention described in Patent Document 1 uses a noble metal, but the noble metal is expensive. However, since noble metals are supported on iron particles, noble metals cannot be easily recovered after using them as a purification material, and it is costly because they are discarded after use. There is a problem of cost.
On the other hand, the thing of patent document 2 has alloyed iron powder and nickel powder by the mechanical alloying method, and there exists a problem that manufacturing cost starts.

  The present invention has been made to solve such a problem, and is an organic halogen compound purification material that has an excellent decomposition rate with respect to groundwater contaminated with an organic halogen compound and can reduce costs, and a purification method using the purification material The purpose is to provide a method for recycling the purification material.

(1) The organic halogen compound purifying material according to the present invention has a first particle composed of metal-supported particles in which a platinum group element or nickel is supported on a carrier, and iron powder, or the surface of the iron powder is nobler than iron. It is formed by mixing second particles made of metal powder coated with metal or metal powder made of iron alloy.

(2) A method for purifying an organic halogen compound according to the present invention is characterized in that the organic halogen compound contained in the treated water is purified by bringing the purifying material described in (1) above into contact with the treated water. is there.

(3) The organic halogen compound purification material recycling method according to the present invention includes a collection step of collecting the used purification material used in the method (2), and separating the first particles from the collected purification material. A separation step and a mixing step of mixing the separated first particles and new iron powder, or metal particles obtained by coating the surface of the iron powder with a metal nobler than iron, or second particles made of metal powder made of an iron alloy It is characterized by comprising.

(4) In the above (3), the separation step is performed by any method of magnetic separation, sieving, or specific gravity separation.

  In the present invention, a metal-supported particle (first particle) supporting a platinum group element or nickel on a carrier, iron powder, or a metal powder in which the surface of the iron powder is coated with a metal nobler than iron, or an iron alloy Since the second particles made of the metal powder are mixed, the organic halogen compound can be decomposed and removed reliably and rapidly, and the metal-supported particles can be recovered, so that the cost can be reduced.

It is explanatory drawing of the experimental apparatus of Example 1 of this invention. It is a graph which shows the experimental result of Example 1 of this invention. It is a graph which shows the experimental result of Example 1 of this invention. It is a graph which shows the experimental result of Example 1 of this invention. It is a graph which shows the experimental result of the comparative example 1 for confirming the effect of Example 1 of this invention. It is a graph which shows the experimental result of the comparative example 1 for confirming the effect of Example 1 of this invention. It is a graph which shows the experimental result of the comparative example 1 for confirming the effect of Example 1 of this invention. It is explanatory drawing of the experimental apparatus of Example 2 of this invention. It is a graph which shows the experimental result of Example 2 of this invention. It is a graph which shows the experimental result of Example 2 of this invention. It is a graph which shows the experimental result of Example 2 of this invention. It is a graph which shows the experimental result of the comparative example 2 for confirming the effect of Example 2 of this invention. It is a graph which shows the experimental result of the comparative example 2 for confirming the effect of Example 2 of this invention. It is a graph which shows the experimental result of the comparative example 2 for confirming the effect of Example 2 of this invention. It is a graph which shows the experimental result of Example 3 of this invention. It is a graph which shows the experimental result of Example 3 of this invention. It is a graph which shows the experimental result of Example 3 of this invention.

[Embodiment 1]
The organic halogen compound purifying material according to one embodiment of the present invention includes a metal-supporting particle (first particle) in which a platinum group element or nickel is supported on a support, and iron powder, or the surface of the iron powder is more iron than iron. It is formed by mixing second particles made of metal powder coated with a noble metal or metal powder made of an iron alloy.
Hereinafter, each configuration will be described in detail.

<First particle>
[Platinum group element or nickel]
As the platinum group element, palladium (Pd), rhodium (Rh), ruthenium (Ru), and platinum (Pt) are particularly preferable.
Nickel is also preferable as the metal element other than the platinum group element.

[Carrier]
As the carrier, an inorganic porous material can be used, and examples thereof include alumina, zeolite, silica, diatom, ceramic, activated carbon and the like.
The larger the specific surface area of the support, the more the area that comes into contact with the treated water and the better the VOC decomposition performance due to dechlorination and hydrogenation by the hydrogenation catalytic reaction. The specific surface area of the carrier is preferably 10 to 1000 m2 / g by the nitrogen-substituted BET method.
Regarding the metal loading, since the carrier cost increases as the metal loading increases, a loading of 0.1 to 5% is preferable.

<Second particle>
2nd particle | grains consist of metal powder which consists of iron powder, the metal powder which coat | covered the surface of iron powder with a metal more nobler than iron, or an iron alloy.
[Iron powder]
As the iron powder, atomized iron powder, reduced iron powder, electrolytic iron powder, shot waste, and the like can be used. Moreover, steel powder and cast iron powder may be sufficient.
[Metal powder with iron powder coated with a metal nobler than iron]
Examples of metals that are more noble than iron include nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), copper (Cu), and cobalt (Co).
[Iron alloy]
As the iron alloy, iron / chromium alloy, iron / aluminum alloy, nickel / iron alloy, cobalt / iron alloy, copper / iron alloy, molybdenum / iron alloy, stainless steel and the like can be used.

As the particle size distribution of the second particles, it is preferable that the particle size of 0.045 mm or more is 50% or more and the maximum particle size is 2 mm. In the particle size distribution of the second particles, when the particle size of less than 0.045 mm is 50% or more, for example, the second particles flow out from a cartridge or the like containing the second particles, and are difficult to collect. On the other hand, when the particle size of the second particles is 2 mm or more, the reactivity becomes low.
Further, when an oxide film is formed on the surface of the second particles, the oxide film should be as thin as possible, preferably 30 nm or less.

  In the organic halogen compound purifying material configured as described above, the metal-supported particles (first particles) have an olefin hydrogenation catalyst function. In addition, the second particles exhibit a purifying action by substituting and hydrogenating the halogen atoms of the organic halogen compound by hydrogen atoms by a local battery reaction that occurs when contacting the metal-supported particle carrier. In particular, any platinum group element has a high potential, and the potential difference between the iron powder or the like and the platinum group element is large, and a local battery reaction occurs effectively.

  The treated water to be treated includes groundwater, factory wastewater, sewage, sewage, washing water, and the like containing organic halogen compounds.

[Embodiment 2]
Specific treatment methods using the purification material of the present embodiment are roughly classified into a method of using the purification material in a container and a method of using the purification material without being contained in the container.
<Method of housing the purification material in the container>
The following modes can be considered as a method of accommodating in a container.
(1) Put the purification material in a cylindrical container and submerge it in the water in the excavation well excavated in the treatment area. A pump is installed in the excavation well, and groundwater is forcibly passed through the container by the pump to purify the groundwater. Collect containers after cleanup is complete. In this case, as a way of putting the purifying material into the container, an aspect in which the purifying material is filled so as not to flow in the container or an aspect in which the purifying material flows in the container may be employed.
(2) The purifying material is accommodated in a container, the container is placed in a storage tank for storing contaminated treated water, and the treated water in the storage tank is circulated so as to pass through the container.
(3) Put the purification material in an irregular and deformable bag and immerse it in contaminated water. Collect the whole bag after the treated water is purified.

<Method of not containing the purification material in the container>
(1) Fluid tank The purifier is put in a cylindrical fluid tank, and treated water is flowed from the lower part to the upper part of the fluid tank, so that the carrier and / or iron powder, etc. constituting the purifier are contained in the fluid tank. To flow. Since the purification material flows, there is no clogging of suspended substances, so there is no pressure loss due to clogging of suspended substances. In addition, the oxide film generated on the surface of the iron powder etc. due to the dissolution of the iron powder etc. is peeled off by the friction during the flow, etc. Can be activated.

(2) Fixed tank A purification material is filled in, for example, a cylindrical fixed tank so that the purification material does not flow to form a packed bed, and treated water is passed through the packed bed. In this case, the direction of water flow does not matter. This method is advantageous in that it is simple and the direction of treated water is not limited.

(3) Stirring tank The purification material is placed in, for example, a shallow cylindrical container, and a rotating blade is provided in the cylindrical container to stir the treated water. Instead of the stirring blade, the treated water may be ejected vigorously from the nozzle to generate a spiral water flow. Also in this case, as in the case of the fluidized tank, the suspended matter is not clogged and there is no pressure loss due to the clogged suspended matter. In addition, the oxide film generated on the surface of the iron powder, etc. due to the dissolution of the iron powder, etc. is peeled off due to friction during flow, etc., and a new surface that is not always covered by the oxide film such as iron can be exposed, and the reaction Can be activated.

  Each processing method described above may be continuous processing or batch processing.

[Embodiment 3]
A method for recycling the purification material will be described.
The purification material recycling method according to the present embodiment includes a recovery step of recovering the used purification material used in the treatment method described in the second embodiment, and metal-supported particles (first particles) from the recovered purification material. ) And a mixing step of mixing the separated metal-carrying particles and second particles of new iron or iron alloy.
Hereinafter, each process will be described in more detail.

<Recovery process>
Of the methods described in the second embodiment, the method of storing the purification material in the container makes it very easy to collect the purification material in the collection process. However, even if the purification material is not contained in the container, it is easy to collect the purification material from each tank.

<Separation process>
If the recovered particles are consolidated, they are crushed and then separated.
The separation step is a step of separating the metal-carrying particles (first particles) from the collected purification material.
Specific embodiments in the separation step include (1) specific gravity sorting, (2) magnetic force sorting, and (3) particle size sorting.
(1) Specific gravity selection is a method for separating metal-supported particles (first particles) and iron powder or the like with a specific gravity difference, and a specific gravity separation device such as a cyclone, jig, or spiral can be used.
(2) Magnetic separation is a method of separating magnetized material (iron powder, etc.) and non-adhered material (metal-supported particles) by magnetic force, and a general-purpose product such as a drum magnetic separator can be used. Since austenite SUS is non-magnetized, it cannot be separated from the metal-carrying particles by magnetic separation, and may be performed by other sorting methods.
(3) Particle size selection is a method of separating metal-supported particles and iron powder from the difference in particle size, and a sieving device can be used.

  The separated metal-supported particles are washed and provided before reuse. Cleaning is performed by removing the surface dirt with acid and activating treatment. As the acid, inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as citric acid, tartaric acid and oxalic acid can be used. In the case of an inorganic acid, if the concentration is too high, the metal supported on the carrier may be dissolved, so it is preferable to use a solution having a concentration of 50% or less.

<Mixing process>
In the mixing step, the metal support particles recovered in the recovery step and subjected to the activation treatment are coated with new iron powder, or metal powder in which the surface of the iron powder is coated with a noble metal than iron, or a metal made of an iron alloy. It is a step of mixing second particles made of powder.
By passing through the mixing step, the purification material is recycled, and the recycled purification material is accommodated in a container or the like according to the usage mode.

[Example 1]
An experiment for confirming the effect of the purifying material according to the present invention was conducted and will be described below.
FIG. 1 is an explanatory diagram of the experimental apparatus used in the first embodiment. As shown in FIG. 1, the experimental apparatus includes a tedla pack 1 that contains VOC-contaminated water and a packed column 3 that contains a purification material, and the tedra pack 1 and the packed column 3 are connected by a pipe 5. A pump 7 is provided on the way, and the contaminated water is supplied to the packed column 3 by the pump 7. A valve 9 is provided in the vicinity of the inlet of the packed column 3, a first sampling port 11 for branching from the valve 9 to sample the pre-treatment water is provided, and a outlet for sampling the post-treatment water is provided at the outlet of the packed column 3. Two sampling ports 13 are provided.

  The packed column 3 is a glass column having a diameter of 2 cm and a length of 20 cm, filled with 35 g of an alumina carrier supporting 0.5% of metallic palladium (Pd) (hereinafter simply referred to as “Pd”), and pure iron. It was configured by filling 85 g of powder. Table 1 shows the BET specific surface area of the Pd-supported alumina support.

VOC-contaminated water (containing 40 mg / l each of cis-1,2-dichloroethylene (DCE), trichlorethylene (TCE), and tetrachloroethylene (PCE)) was passed through the packed column 3 in an upward flow from the bottom.
The pump 7 is of a variable flow rate type, whereby the flow rate supplied to the packed column 3 is variable. Moreover, PTFE material was used for the tedora pack 1, each piping, and the sampling valve so that the concentration of VOC-contaminated water would not change.

Change the water flow rate, sample the initial treated water before treatment from the first sampling port 11, sample the treated water after treatment from the second sampling port 13, and measure the VOC concentration by the GC-MS headspace method did. The measurement results are shown in Table 2 and FIGS.

  2 to 4 are graphs showing the relationship between the water flow rate and the VOC concentration. In each figure, the horizontal axis indicates the SV value (water flow rate per hour / packed column volume) (1 / h). Yes. Also, the vertical axis represents the DCE concentration ratio (post-treatment concentration / initial concentration) in FIG. 2, the TCE concentration ratio (post-treatment concentration / initial concentration) in FIG. 3, and the PCE concentration ratio (post-treatment concentration / initial concentration) in FIG. Respectively.

  As can be seen from Table 2 and FIGS. 2 to 4, excellent decomposition performance is exhibited for any of DCE, TCE, and PCE. It can also be seen that the larger the specific surface area of the Pd-supported carrier, the better the decomposition performance.

[Comparative Example 1]
In order to confirm the effect of loading Pd on the support, the same experiment as in Example 1 was performed when Pd and Ni were coated on the upper surface of pure iron powder without loading Pd on the alumina balls. It was. The experimental contents of Comparative Example 1 are as follows.
The same glass column as in Example 1 was filled with alumina balls and Pd-coated iron powder coated with 0.1% by mass of Pd black for catalyst on the surface of pure iron powder. As another example, the same device as in Example 1 was filled with alumina balls and Ni-coated iron powder coated with 0.2% by mass of metallic nickel having an average particle size of 0.4 μm on the surface of pure iron powder. The reason why the packed balls are packed in the packed column is to form a water flow environment similar to that in the first embodiment in the packed column.
Water was passed in the same manner as in Example 1 and the VOC concentration was measured. The results are shown in Table 3 and Figs.

As can be seen from Table 3 and FIGS. 5 to 7, the decomposition performance of VOC is inferior compared to the examples. For example, the concentration ratio of DCE at SV = 30 of Pd-supported carrier A in Example 1 is 0.00145 (see FIG. 2), whereas the concentration ratio of DCE at SV = 30 of Pd-coated iron powder in Comparative Example 1 Is 0.2375, and it can be seen that Example 1 has a decomposition performance of 100 times or more.
From the comparison between Example 1 and Comparative Example 1, it can be seen that the use of Pd supported on an alumina carrier significantly improves the VOC decomposition performance compared with the use of Pd coated on the iron powder surface.

[Example 2]
In Example 2, it confirmed about the effect at the time of using the purification material of this invention by a batch processing system. FIG. 8 is an explanatory diagram of the experimental apparatus of the second embodiment. In the experimental apparatus of Example 2, 95 ml of VOC-contaminated water 17 (containing 10 mg / l each of DCE, TCE, and PCE) is placed in a vial 15 having a capacity of 100 ml, and a purifier 19 is placed therein, and a PTFE septum is placed therein. 21 is hermetically sealed.
The purification material 19 is a mixture of 13 g of an alumina carrier carrying 0.5% of metal Pd and 33 g of pure iron powder having an average particle size of 110 μm. The Pd-supported alumina carrier is the same as the Pd-supported carriers A to C shown in Table 1 used in Example 1.
Water was collected every predetermined time while rotating the vial 15 at 30 rpm, and the VOC concentration was measured by GC-MS. The results are shown in Table 4 and FIGS.

    9 to 11 are graphs showing the relationship between the water flow rate and the VOC concentration, and in each figure, the horizontal axis shows the reaction (residence) time (min). The vertical axis represents the DCE concentration ratio (post-treatment concentration / initial concentration) in FIG. 9, the TCE concentration ratio (post-treatment concentration / initial concentration) in FIG. 10, and the PCE concentration ratio (post-treatment concentration / initial concentration) in FIG. Respectively.

  As can be seen from Table 4 and FIGS. 9 to 11, even in the case of the batch processing method, the purification material of the present invention sufficiently exhibits the VOC decomposition performance. It can also be seen that, as in Example 1, the larger the specific surface area of the Pd-supported carrier is, the better the decomposition performance is.

[Comparative Example 2]
In the case of batch processing, as in Comparative Example 1, in order to confirm the effect of loading Pd on the carrier, the Pd was not loaded on the alumina balls, and the pure iron powder and pure iron powder were formed on the upper surface. The same experiment as in Example 2 was performed when Pd and Ni were coated. The experimental contents of Comparative Example 2 are as follows.
95 ml of VOC-contaminated water 17 (containing 10 mg / l each of DCE, TCE, and PCE) was placed in a 100 ml vial 15, 13 g of 3Φ alumina balls and 33 g of various iron powders were placed and sealed with a PTFE septum 21.
As the iron powder, a: pure iron powder, b: Ni coated iron powder coated with 0.2% metallic Ni, and c: Pd coated iron powder coated with 0.1% Pd black were used.
Water was collected every predetermined time while rotating the vial 15 at 30 rpm, and the VOC concentration was measured by GC-MS. The results are shown in Table 5 and Figs.

  As can be seen from Table 5 and FIGS. 12 to 14, in the case of Comparative Example 2, it can be seen that the VOC decomposition performance is extremely low. Even when compared with Comparative Example 1, Comparative Example 2 is inferior in decomposition performance. The reason for this is that, in Comparative Example 1, the purifying material was filled 3 in the packed column and passed, whereas in Comparative Example 2, the purifying material was placed in the vial 15 and the vial 15 was rotated. Therefore, it is surmised that Comparative Example 1 was more easily contacted with the treated water and the purification material. In this regard, in Example 2, since the decomposition performance almost equivalent to that in Example 1 was exhibited, it was confirmed that the purification material of the present invention was excellent in decomposition performance even in the batch processing method.

[Example 3]
In the present Example 3, since the experiment which confirms the influence which it has on the decomposition | disassembly performance at the time of recycling a purification material was conducted, the content and result are shown below.
The packed material was extracted from the packed column 3 packed with the Pd-supported carrier B of Example 1 that had been subjected to water treatment for 3 months, and classified with a 2.0 mm sieve. The Pd-supported carrier B and the consolidated iron powder remaining on the sieve were subjected to magnetic separation with a 1000 gauss permanent magnet, and only the Pd-supported carrier B was recovered.
In addition, iron powder under the sieve was also collected separately. The recovered material was washed with water and then vacuum-dried. The same test as in Example 2 was performed using Pd-supported carrier B after vacuum drying. The results are shown in Table 6 and FIGS. In Table 6 and FIGS. 15 to 17, the results when using a new Pd carrier B are also shown.

  As shown in Table 6 and FIGS. 15 to 17, it was confirmed that even after the water flow treatment for 3 months, the VOC resolution was almost the same as that of the new product. As a result, it was confirmed that the purification material of the present invention can be used without degrading the VOC decomposition performance even if it is recycled.

1 Tedra Pack 3 Packing Column 5 Piping 7 Pump 9 Valve 11 First Sampling Port 13 Second Sampling Port 15 Vial Bottle 17 VOC Contaminated Water 19 Purifier 21 Septum

Claims (4)

  From the 1st particle | grains which consist of the metal carrying | support particle | grains which carry | supported the platinum group element or nickel on the support | carrier, and the metal powder which coat | covered the iron powder or the surface of the iron powder with a noble metal rather than iron, or the metal powder which consists of an iron alloy An organic halogen compound purification material obtained by mixing the second particles.   A purification method of an organic halogen compound, wherein the purification material according to claim 1 is brought into contact with treated water to purify an organic halogen compound contained in the treated water.   A recovery step of recovering the used purification material used in the method of claim 2, a separation step of separating the first particles from the recovered purification material, the separated first particles and new iron powder, or iron powder A method of recycling an organic halogen compound purifying material, comprising: mixing a metal powder having a surface coated with a metal noble than iron or a second particle made of a metal powder made of an iron alloy.   The method for recycling an organic halogen compound purification material according to claim 3, wherein the separation step is performed by any one of magnetic separation, sieving, and specific gravity separation.

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