JP5982347B2 - Iron powder for purifying groundwater and method for producing the same - Google Patents
Iron powder for purifying groundwater and method for producing the same Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims description 188
- 239000003673 groundwater Substances 0.000 title claims description 49
- 238000004519 manufacturing process Methods 0.000 title claims description 29
- 239000000843 powder Substances 0.000 claims description 66
- 239000002245 particle Substances 0.000 claims description 53
- 238000000746 purification Methods 0.000 claims description 42
- 229910052739 hydrogen Inorganic materials 0.000 claims description 20
- 239000001257 hydrogen Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 19
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 17
- 235000013980 iron oxide Nutrition 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 14
- 239000003575 carbonaceous material Substances 0.000 claims description 13
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 150000002431 hydrogen Chemical class 0.000 claims description 9
- 238000010298 pulverizing process Methods 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 7
- 239000012855 volatile organic compound Substances 0.000 description 19
- 238000000354 decomposition reaction Methods 0.000 description 18
- 229910052742 iron Inorganic materials 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 14
- 230000002829 reductive effect Effects 0.000 description 14
- 239000002689 soil Substances 0.000 description 11
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 8
- KFUSEUYYWQURPO-UPHRSURJSA-N cis-1,2-dichloroethene Chemical compound Cl\C=C/Cl KFUSEUYYWQURPO-UPHRSURJSA-N 0.000 description 7
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 7
- 239000000571 coke Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 5
- 150000002896 organic halogen compounds Chemical class 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 150000004045 organic chlorine compounds Chemical class 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- ULGZDMOVFRHVEP-RWJQBGPGSA-N Erythromycin Chemical compound O([C@@H]1[C@@H](C)C(=O)O[C@@H]([C@@]([C@H](O)[C@@H](C)C(=O)[C@H](C)C[C@@](C)(O)[C@H](O[C@H]2[C@@H]([C@H](C[C@@H](C)O2)N(C)C)O)[C@H]1C)(C)O)CC)[C@H]1C[C@@](C)(OC)[C@@H](O)[C@H](C)O1 ULGZDMOVFRHVEP-RWJQBGPGSA-N 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 230000003203 everyday effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- -1 Cu are used Chemical class 0.000 description 1
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011246 composite particle Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 150000004968 peroxymonosulfuric acids Chemical class 0.000 description 1
- 239000012629 purifying agent Substances 0.000 description 1
- 230000036647 reaction Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229950011008 tetrachloroethylene Drugs 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
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Description
本発明は、揮発性有機ハロゲン化合物や重金属で汚染された地下水および土壌を浄化するための地下水浄化用鉄粉およびその製造方法に関するものである。 The present invention relates to groundwater purification iron powder for purifying groundwater and soil contaminated with volatile organic halogen compounds and heavy metals, and a method for producing the same.
トリクロロエチレンやテトラクロロエチレンなど揮発性有機ハロゲン化合物で汚染された土壌や地下水等を原位置で浄化する手法として、鉄粉その他金属粉による還元分解法や、過硫酸、過酸化水素水を用いた酸化分解法などが実用化されている。 In-situ purification methods for soil and groundwater contaminated with volatile organic halogen compounds such as trichlorethylene and tetrachlorethylene include reductive decomposition using iron powder and other metal powders, and oxidative decomposition using persulfuric acid and hydrogen peroxide. Etc. have been put to practical use.
例えば、特許文献１には、地下水水位より深部に位置する土壌や、地下水水位より浅部に位置する土壌、並びに掘削した土壌であって、かつ有機塩素系化合物で汚染された土壌に、鉄粉を添加・混合し、有機塩素系化合物を分解することによって、土壌を浄化する土壌の無害化処理方法が開示されている。また、この方法に適した鉄粉として、0.1重量％以上の炭素を含みかつ500cm2/g以上の比表面積を有すると共に、50重量％以上が150μmのふるいを通過する粒度を有している鉄粉が示されている。 For example, in Patent Document 1, iron powder is applied to soil located deeper than the groundwater level, soil located shallower than the groundwater level, and excavated soil that is contaminated with an organochlorine compound. A method for detoxifying soil is disclosed in which soil is purified by adding and mixing to decompose organic chlorinated compounds. Further, as iron powder suitable for this method, iron containing 0.1% by weight or more of carbon and having a specific surface area of 500 cm 2 / g or more and having a particle size of 50% by weight or more passing through a 150 μm sieve. Powder is shown.
このような、鉄粉による有機塩素化合物の還元分解は、鉄粉表面において、分解対象物に電子を受け渡すことで反応が進行すると考えられている。従って、分解対象物との接触確率が増えるように鉄表面の面積が大きいもの、すなわち鉄粉の比表面積が大きいものほど、有機塩素化合物の分解速度は大きくなる傾向にある。 Such reductive decomposition of an organic chlorine compound by iron powder is considered to proceed by transferring electrons to the decomposition target on the iron powder surface. Accordingly, the decomposition rate of the organic chlorine compound tends to increase as the surface area of the iron surface increases, that is, the specific surface area of the iron powder increases so that the probability of contact with the decomposition target increases.
また、有機塩素化合物の分解速度を大きくするためには、比表面積を大きくする手法に加え、様々な手法が検討されている。例えば、特許文献２、３には、銅を含有もしくは被着させた鉄粉が、また特許文献４には、Niを被着させた鉄粉などがそれぞれ開示されている。これらは、鉄表面に鉄より貴な金属を付着させることで、局部電池を形成させ、鉄からの電子供給を起こり易くしたものである。 In addition to increasing the specific surface area, various methods are being studied in order to increase the decomposition rate of organochlorine compounds. For example, Patent Documents 2 and 3 disclose iron powder containing or deposited copper, and Patent Document 4 discloses iron powder deposited with Ni and the like. In these, a noble metal than iron is adhered to the iron surface, thereby forming a local battery and facilitating the supply of electrons from the iron.
他方、鉄よりも貴な金属ではなく、金属酸化物や硫化物を鉄表面に被着させた鉄粉なども検討されていて、特許文献５〜７には、鉄とマグネタイトによる複合粒子の例が示されている。 On the other hand, iron powders in which metal oxides and sulfides are deposited on the iron surface, not a noble metal than iron, have been studied. Patent Documents 5 to 7 include examples of composite particles of iron and magnetite. It is shown.
上記のように、鉄粉による有機ハロゲン化合物の還元分解では、その反応速度を大きくするために、
（１）比表面積を大きくする、
（２）鉄表面に第２の導電性物質を被着させて、局部電池を形成する
などの方法がとられる。
As mentioned above, in reductive decomposition of organic halogen compounds with iron powder, in order to increase the reaction rate,
(1) increase the specific surface area,
(2) A method of forming a local battery by depositing a second conductive material on the iron surface is employed.
ここで、特許文献１では、単純に比表面積を大きくすればよいとしているが、一般に、比表面積を大きくするには、粒子を細かくすればよいものの、金属粉末を細粒化すると、自然発火する可能性が増大し、その取り扱いには、細心の注意が必要となる。 Here, in Patent Document 1, it is only necessary to simply increase the specific surface area, but in general, to increase the specific surface area, it is only necessary to make the particles finer, but when the metal powder is made finer, it spontaneously ignites. The possibilities increase and the handling requires great care.
他方、特許文献５〜７では、鉄-マグネタイトの微粒子が浄化剤として示されているが、その製法は、酸化鉄を原料とし、水素還元して、微粒子の鉄粉を製造した後に、引続き、処理雰囲気を制御しつつ徐酸化し、鉄表面をマグネタイト化することで、発火を抑える工程が必要である。従って、この方法では、酸化鉄の還元時に多量の水素を要すると同時に、高温での処理が必要となるため、製造コストがかかることになる。さらに、一度還元した後に、再び表面を酸化するため、その製造プロセスも煩雑となる。 On the other hand, in Patent Documents 5 to 7, iron-magnetite fine particles are shown as a purifying agent, but the production method is continued after iron oxide is used as a raw material and hydrogen reduction is performed to produce fine iron powder. There is a need for a step of suppressing ignition by slowly oxidizing while controlling the treatment atmosphere and magnetizing the iron surface. Therefore, this method requires a large amount of hydrogen during the reduction of iron oxide, and at the same time requires treatment at a high temperature, resulting in high manufacturing costs. Further, since the surface is oxidized again after being reduced once, the manufacturing process becomes complicated.
さらに、特許文献２〜４に示されているような鉄よりも貴な金属を鉄粉表面に被着させた浄化剤は、その製造方法が比較的簡便ではあるものの、元々、NiやCo、Cuなどの高価な金属を使用するために、浄化剤の価格が高くなるという問題を有していた。 Furthermore, the purification agent in which a metal noble than iron as shown in Patent Documents 2 to 4 is deposited on the surface of the iron powder, although its manufacturing method is relatively simple, originally Ni, Co, Since expensive metals such as Cu are used, there is a problem that the price of the cleaning agent becomes high.
また、土壌浄化では、これら鉄粉を汚染土壌と混合して浄化した後も放置することが多いため、NiやCuでは、それ自体が有害物質となる可能性があって、好ましくない。 Further, in soil purification, these iron powders are often left after being mixed with the contaminated soil and purified, so Ni and Cu are not preferable because they may become harmful substances themselves.
なお、鉄粉による有機ハロゲン化合物の還元分解の基本原理は、鉄粉表面での電子の授受によると考えられるが、一般に、浄化工法ごとに、適した浄化剤が存在している。なかでも、鉄粉層に汚染水を通水し、鉄粉層を通過する間に分解反応を起こさせる地下水の浄化工法に適した浄化剤は、従来、ダライコ、鋳物くずといった安価な発生粉が使用されてきたが、その浄化性能は十分ではなかった。 The basic principle of reductive decomposition of organic halogen compounds with iron powder is considered to be transfer of electrons on the surface of iron powder, but generally there is a suitable purifier for each purification method. Among them, cleansing agents suitable for groundwater purification methods that cause contaminated water to flow through the iron powder layer and cause a decomposition reaction while passing through the iron powder layer have conventionally been low-priced powder such as dariko and foundry scrap. Although it has been used, its purification performance has not been sufficient.
本発明は、上記した現状に鑑み開発されたもので、鉄粉層に汚染水を通水し、鉄粉層を通過する間に分解反応を起こさせる地下水の浄化工法に適した鉄粉を提供することを目的とする。 The present invention has been developed in view of the above-described present situation, and provides iron powder suitable for a groundwater purification method that causes contaminated water to flow through the iron powder layer and causes a decomposition reaction while passing through the iron powder layer. The purpose is to do.
すなわち、本発明の要旨構成は次のとおりである。 That is, the gist configuration of the present invention is as follows.
１．地下水浄化用鉄粉の製造工程において、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、粒子径：0.1〜10μmのNi粉を混合し、ついで、水素中で仕上げ還元を施すことで、Niを鉄粉表面に拡散付着させることを特徴とする地下水浄化用鉄粉の製造方法。 1 . In the production process of groundwater purification iron powder, one or more selected from ores, mill scales and iron oxides are used as raw materials to perform rough reduction with carbonaceous materials to obtain roughly reduced iron powder. The coarse reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, Ni powder having a particle size of 0.1 to 10 μm is mixed, and then subjected to finish reduction in hydrogen, whereby Ni is converted into iron powder. A method for producing iron powder for purifying groundwater, characterized by being diffused and adhered to a surface.
２．地下水浄化用鉄粉の製造工程において、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、水素中で仕上げ還元し、さらに粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させることを特徴とする地下水浄化用鉄粉の製造方法。 2 . In the production process of groundwater purification iron powder, one or more selected from ores, mill scales and iron oxides are used as raw materials to perform rough reduction with carbonaceous materials to obtain roughly reduced iron powder. The coarse reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, subjected to finish reduction in hydrogen, and further mixed with Ni powder having a particle size of 0.1 to 10 μm, followed by vigorous stirring. A method for producing iron powder for purifying groundwater, characterized by mechanically adhering to the surface of the iron powder.
３．地下水浄化用鉄粉の製造工程において、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、さらに粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させることを特徴とする地下水浄化用鉄粉の製造方法。 3 . In the production process of groundwater purification iron powder, one or more selected from ores, mill scales and iron oxides are used as raw materials to perform rough reduction with carbonaceous materials to obtain roughly reduced iron powder. By classifying the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm, and further mixing Ni powder with a particle size of 0.1 to 10 μm and stirring vigorously, Ni is mechanically applied to the iron powder surface. A method of producing iron powder for purifying groundwater, characterized in that it is adhered to a surface.
４．地下水浄化用鉄粉の製造工程において、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、粒子径0.1〜10μmのNi粉を混合し、ついで、水素中で仕上げ還元を施すことでNiを鉄粉表面に拡散付着させた鉄粉と、上記粉砕工程で、粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級したのち、水素中で仕上げ還元し、ついで粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させた鉄粉と、を混合させることを特徴とする地下水浄化用鉄粉の製造方法。 4 . In the production process of groundwater purification iron powder, one or more selected from ores, mill scales and iron oxides are used as raw materials to perform rough reduction with carbonaceous materials to obtain roughly reduced iron powder. The coarse reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, mixed with Ni powder having a particle size of 0.1 to 10 μm, and then subjected to finish reduction in hydrogen so that Ni is applied to the iron powder surface. After diffusing and adhering the iron powder, in the above pulverization step, the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, then subjected to finish reduction in hydrogen, and then Ni powder having a particle size of 0.1 to 10 μm is obtained. A method for producing iron powder for purifying groundwater, comprising mixing iron powder with mechanically adhering Ni to the iron powder surface by vigorous stirring.
なお、これらの地下水浄化用鉄粉は、地下水を浄化する目的で、カラムなどに充填され、汚染水を通水することで、水中のVOC（揮発性有機化合物）を分解除去する浄化剤とすることができる。そして、浄化が終了した際には、これらカラム中に充填している鉄粉を回収することで、Niなど重金属による２次的な汚染を回避することができる。 These iron powders for purifying groundwater are used as purifiers to decompose and remove VOCs (volatile organic compounds) in the water by filling contaminated water through the column for the purpose of purifying groundwater. be able to. And when purification | cleaning is complete | finished, the secondary contamination by heavy metals, such as Ni, can be avoided by collect | recovering the iron powder with which these columns are filled.
本発明によれば、有機ハロゲン化合物などで汚染された地下水を、短時間で浄化できる浄化剤を提供することができる。
また、本発明によれば、鉄よりも貴なNi金属は用いるが、これら鉄粉層に汚染水を通水して分解させることで、土壌中にこれら有害金属を放置することなく、かつVOCを効率的に分解除去することができる。
ADVANTAGE OF THE INVENTION According to this invention, the purification agent which can purify | clean the groundwater contaminated with the organic halogen compound etc. in a short time can be provided.
Further, according to the present invention, Ni metal, which is nobler than iron, is used, but by passing contaminated water through these iron powder layers and decomposing them, these toxic metals are not left in the soil and VOCs are left. Can be efficiently decomposed and removed.
以下、本発明を具体的に説明する。
本発明の第１の実施形態である地下水浄化用鉄粉は、粒子径が0.2〜5.0mmの範囲で、かつ比表面積の平均が0.1m2/g以上である還元鉄粉の表面にNiが付着し、さらに地下水浄化用鉄粉に対するNiの含有率（地下水浄化用鉄粉中のNiの含有率（内数）を意味する）を0.4〜３mass％とするものである。
すなわち、本発明における浄化剤は、上記地下水浄化用鉄粉を用いるものである。
Hereinafter, the present invention will be specifically described.
The iron powder for groundwater purification according to the first embodiment of the present invention has Ni on the surface of the reduced iron powder having a particle diameter in the range of 0.2 to 5.0 mm and an average specific surface area of 0.1 m 2 / g or more. Furthermore, the Ni content relative to the iron powder for groundwater purification (meaning the Ni content (internal number) in the iron powder for groundwater purification) is 0.4 to 3 mass%.
That is, the purification agent in the present invention uses the above-mentioned iron powder for purifying groundwater.
先にも述べたように、金属鉄もしくはその複合粉を用いた場合、反応速度を大きくするためには、粒子の比表面積を大きくすることが好ましいが、具体的には、粒子平均で0.1m2/g以上とすることが好ましい。0.1m2/g未満では、反応速度が小さくなって、水の浄化には適さない。一方、5.0m2/gを越えると、常温空気中でも激しく酸化反応が進行して、発熱や、発火の危険性があるため、安全上好ましくない。なお、本発明における比表面積は、BET法により、表面にN2を吸着させて、その吸着量から求めることができる。 As described above, when metallic iron or a composite powder thereof is used, in order to increase the reaction rate, it is preferable to increase the specific surface area of the particles, but specifically, the average particle size is 0.1 m. 2 / g or more is preferable. If it is less than 0.1 m 2 / g, the reaction rate becomes small and it is not suitable for purification of water. On the other hand, if it exceeds 5.0 m 2 / g, the oxidation reaction proceeds vigorously even in room temperature air, and there is a risk of heat generation or ignition, which is not preferable for safety. The specific surface area in the present invention can be determined from the amount of adsorption by adsorbing N 2 on the surface by the BET method.
本発明に用いる鉄粉の粒子径は、0.2〜5.0mmの間にあることが必須である。本発明における鉄粉の粒子径が0.2〜5.0mmのものとは、JIS Z 8801号に定める篩いを用いるものであって、5.0mm目開きの篩いを通過し、0.2mm目開きの篩いの上に残るもののことである。本鉄粉は、カラム等に充填して、VOCなど有害物質を含有する汚染水を通水して、鉄粉と接触させることで、VOCを分解浄化するが、鉄粉が細かいと、目詰まりが生じ、通水を妨げる。一方粒子径が大きくなると、一般に比表面積が小さくなり、単位質量当たりの分解性能（速度）が低下する。 The particle size of the iron powder used in the present invention must be between 0.2 and 5.0 mm. The iron powder having a particle size of 0.2 to 5.0 mm in the present invention uses a sieve defined in JIS Z 8801, passes through a sieve with a 5.0 mm opening, and passes over a sieve with a 0.2 mm opening. It is what remains. This iron powder is packed in a column, etc., and VOC is decomposed and purified by passing contaminated water containing VOCs and other harmful substances into contact with the iron powder. Occurs, preventing water flow. On the other hand, when the particle size is increased, the specific surface area is generally decreased, and the decomposition performance (speed) per unit mass is decreased.
また、本発明における鉄粉は、地下水浄化用鉄粉の総質量に対してNiを0.4〜３mass％含有しているが、そのNiの多くは、鉄粉表面に付着している。なお、Ni：0.4mass％未満では、十分な分解性能を得ることができない。一方、Niは高価であり、さらに土壌・地下水の２次的な汚染を防止する意味からもNiの含有率は、３mass％以下である必要がある。 Moreover, although the iron powder in this invention contains 0.4-3 mass% of Ni with respect to the total mass of the iron powder for groundwater purification, most of the Ni is adhering to the iron powder surface. In addition, when Ni is less than 0.4 mass%, sufficient decomposition performance cannot be obtained. On the other hand, Ni is expensive, and the Ni content needs to be 3 mass% or less from the viewpoint of preventing secondary contamination of soil and groundwater.
以下、地下水浄化用鉄粉の製造工程について説明する。
本発明の第２の実施形態として挙げられるのは、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、上記粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、粒子径：0.1〜10μmのNi粉を混合し、ついで、水素中で仕上げ還元を施すことによって、Niを鉄粉表面に拡散付着させる地下水浄化用鉄粉の製造方法である。
Hereinafter, the manufacturing process of the iron powder for groundwater purification is demonstrated.
As a second embodiment of the present invention, after one or more selected from ores, mill scales and iron oxides are used as raw materials, rough reduction with carbonaceous materials is carried out to obtain roughly reduced iron powder. In the pulverization step, the coarse reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, Ni powder having a particle size of 0.1 to 10 μm is mixed, and then subjected to finish reduction in hydrogen, This is a method for producing iron powder for groundwater purification in which Ni is diffused and adhered to the iron powder surface.
上記製造方法をさらに詳述すると、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上とコークスなどの炭材とを層状に充填した還元容器を、容器ごとトンネル炉もしくはバッチ炉に装入し、1000〜1200℃の温度範囲で熱処理することにより粗還元をして粗還元鉄粉とし、その後解砕をする。ついで、予め粒度を上述のように調整した粗還元鉄粉と上記適正量のNiとを混合し、その後に、H2中で、鉄粉の比表面積の平均を0.1m2/g以上としつつ、鉄粉の仕上げ還元を行うと同時に、Ni粒子を、鉄粉中のNiの含有率を0.4〜３mass％としつつ、鉄表面に拡散付着させる工程を経ることが肝要となる。 The above production method will be described in more detail. A reduction vessel in which one or two or more selected from ores, mill scales and iron oxides and a carbonaceous material such as coke are packed in layers, and the vessel together with a tunnel furnace or a batch furnace. And then roughly reduced by heat treatment in a temperature range of 1000 to 1200 ° C. to obtain roughly reduced iron powder, which is then crushed. Next, the coarsely reduced iron powder whose particle size is adjusted in advance as described above and the appropriate amount of Ni are mixed, and then the average specific surface area of the iron powder is set to 0.1 m 2 / g or more in H 2. At the same time as the finish reduction of the iron powder, it is important that the Ni particles are subjected to a step of diffusing and adhering to the iron surface while setting the Ni content in the iron powder to 0.4 to 3 mass%.
この形態において、Niの一部は、鉄粉粒子中に拡散し合金化している。なお、使用する混合機は、容器回転式のダブルコーンミキサーやＶ型混合機が適しており、その混合条件はそれぞれの常法に従えば良い。また、仕上げ還元に使用する炉は、連続炉でも、バッチ炉でもよく、使用するH2量は、0.5〜２L/min/kg-鉄粉、還元温度は550〜1000℃とし、還元時間は１時間程度とするのが好ましい。還元温度が高すぎるとNiが完全に合金化して局部電池反応点が減少するため、低温の方が好ましいが、温度が550℃より低すぎると鉄粉との付着力が弱くなる傾向にある。 In this form, a part of Ni is diffused and alloyed in the iron powder particles. In addition, the mixer to be used is suitable for a container rotation type double cone mixer or a V-type mixer, and the mixing condition may be in accordance with each ordinary method. The furnace used for the finishing reduction may be a continuous furnace or a batch furnace. The amount of H 2 used is 0.5 to 2 L / min / kg-iron powder, the reduction temperature is 550 to 1000 ° C., and the reduction time is 1. It is preferable to set the time to about. If the reduction temperature is too high, Ni will be completely alloyed and the local cell reaction point will decrease, so a lower temperature is preferable. However, if the temperature is lower than 550 ° C., the adhesion to iron powder tends to be weak.
このようにして得られた鉄粉は、その浄化性能において、反応開始直後から、高い分解性能を示し、VOC中のTCE（トリクロロエチレン）やcis-1,2-DCE（cis-1,2-ジクロロエチレン）の分解性に優れている。 The iron powder obtained in this way shows high decomposition performance in the purification performance immediately after the start of the reaction. TCE (trichloroethylene) and cis-1,2-DCE (cis-1,2-dichloroethylene) in VOC ).
本発明の第３の実施形態として挙げられるのは、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、水素中で仕上げ還元し、さらに粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させる地下水浄化用鉄粉の製造方法である。 As a third embodiment of the present invention, after one or more selected from ores, mill scales and iron oxides are used as raw materials, rough reduction with carbonaceous materials is performed to obtain roughly reduced iron powder. In the pulverization step, the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, subjected to finish reduction in hydrogen, and further mixed with Ni powder having a particle size of 0.1 to 10 μm and vigorously stirred. By this, it is the manufacturing method of the iron powder for groundwater purification which makes Ni adhere mechanically to the iron powder surface.
本発明の第４の実施形態として挙げられるのは、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級し、粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させる地下水浄化用鉄粉の製造方法である。 The fourth embodiment of the present invention is that after one or more selected from ores, mill scales and iron oxides are used as raw materials, rough reduction with carbonaceous materials is performed to obtain roughly reduced iron powder. In the pulverization step, the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, and Ni powder having a particle size of 0.1 to 10 μm is mixed and vigorously stirred, so that Ni is applied to the iron powder surface. It is a manufacturing method of iron powder for groundwater purification made to adhere mechanically.
上記第３の実施形態による製造方法では、粗還元およびその後の解砕、さらには、予め粒度を調整した粗還元鉄粉を得るまでは、前記第２の実施形態と同じであって、その後、Niと混合することなく、水素中で、鉄粉の比表面積の平均を0.1m2/g以上としつつ仕上げ還元を行ったのち、得られた仕上げ還元鉄粉とNi粉を強撹拌することで、鉄粉中のNiの含有率を0.4〜３mass％としつつ、鉄粉表面にNiを機械的に付着させることを特徴とする。また、第４の実施形態による製造方法では、仕上げ還元を行わない比表面積の平均を0.1m2/g以上の粗還元鉄粉に、Ni粉を強撹拌することで、鉄粉中のNiの含有率を0.4〜３mass％としつつ、鉄粉表面にNiを機械的に付着させることを特徴とする。 In the manufacturing method according to the third embodiment, rough reduction and subsequent pulverization, and further, until obtaining coarsely reduced iron powder whose particle size has been adjusted in advance, are the same as in the second embodiment, After mixing and reducing the average specific surface area of the iron powder to 0.1 m 2 / g or more in hydrogen without mixing with Ni, the resulting reduced iron powder and Ni powder are stirred vigorously. The Ni content in the iron powder is 0.4 to 3 mass%, and Ni is mechanically adhered to the iron powder surface. In addition, in the manufacturing method according to the fourth embodiment, Ni powder is vigorously stirred into coarsely reduced iron powder having an average specific surface area of 0.1 m 2 / g or more without final reduction. It is characterized in that Ni is mechanically adhered to the iron powder surface while the content rate is 0.4-3 mass%.
第３および第４の実施形態による製造方法では、いずれも、Niは、鉄と合金化していない。ここで使用する混合機としては、ヘンシェルミキサーや、アイリッヒミキサーなどが適しており、その混合条件はそれぞれの常法に従えば良い。例えば、アイリッヒミキサー(日本アイリッヒ社製)を使用した場合は、鉄粉に対して、粒子径：0.1μmのNiを0.5mass％分添加して混合することで、鉄粉表面に、Niを付着させることができる。かかる手順で付着させたNiは、大きく変形して、鉄粉表面を覆っている。 In both the manufacturing methods according to the third and fourth embodiments, Ni is not alloyed with iron. As a mixer used here, a Henschel mixer, an Eirich mixer, etc. are suitable, and the mixing conditions should just follow each usual method. For example, when using an Eirich mixer (manufactured by Eirich Japan), Ni is added to the iron powder surface by adding 0.5 mass% of Ni with a particle size of 0.1 μm to the iron powder surface. Can be attached. Ni deposited by such a procedure is greatly deformed and covers the iron powder surface.
このようにして得られた鉄粉の浄化性能は、反応開始直後、あまりよく反応しないものの、徐々に反応速度が増加し、最終的には、高い分解性能を示す。さらにその持続時間も長い。また、VOC中、TCEやcis-1,2-DCEだけでなく、PCEともよく反応するという特徴を有している。PCEとよく反応する理由は、よくわかっていないが、一般的に、TCE、cis-1,2-DCE、PCEの中では、PCEが一番反応しにくいとされていて、熱処理で部分合金化したものに比べると、機械的に付着させたものの方が反応性に富んでいるため、その分、PCEを分解できたと考えられる。 Although the purification performance of the iron powder obtained in this way does not react very well immediately after the start of the reaction, the reaction rate gradually increases and finally shows high decomposition performance. Furthermore, the duration is long. It also has the feature that it reacts well with PCE as well as TCE and cis-1,2-DCE in VOC. The reason why it reacts well with PCE is not well understood, but generally it is said that PCE is the least reactive among TCE, cis-1,2-DCE, and PCE. Compared to the above, the mechanically attached material is more reactive, so it is thought that PCE could be decomposed accordingly.
本発明の第５の実施形態として挙げられるのは、鉱石、ミルスケールおよび酸化鉄の内から選んだ１種もしくは２種以上を原料として、炭材による粗還元を行い粗還元鉄粉としたのち、粉砕工程で、該粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級して、粒子径0.1〜10μmのNi粉を混合し、ついで、水素中で仕上げ還元を施すことでNiを鉄粉表面に拡散付着させた鉄粉と、上記粉砕工程で、粗還元鉄粉の粒子径が0.2〜5.0mmのものを分級したのち、水素中で仕上げ還元し、さらに粒子径：0.1〜10μmのNi粉を混合して強撹拌をすることで、Niを鉄粉表面に機械的に付着させた鉄粉と、を混合させることを特徴とする地下水浄化用鉄粉の製造方法である。具体的には、第２の実施形態と第３の実施形態で製造された鉄粉を混合することで得ることができる。本混合は、容器回転式のダブルコーンミキサーやＶ型混合機を用いればよく、その混合条件は、それぞれの常法に従えばよい。 As a fifth embodiment of the present invention, one or more selected from ores, mill scales, and iron oxides are used as raw materials to perform rough reduction with a carbonaceous material to obtain roughly reduced iron powder. In the pulverization step, the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm is classified, Ni powder having a particle size of 0.1 to 10 μm is mixed, and then Ni is added by performing final reduction in hydrogen. After classifying the iron powder diffused and adhered to the surface of the iron powder and the coarsely reduced iron powder having a particle size of 0.2 to 5.0 mm in the above pulverization step, finish reduction in hydrogen, and further the particle size: 0.1 to 10 μm This is a method for producing iron powder for purifying groundwater, which comprises mixing Ni powder and vigorously stirring to mix iron powder in which Ni is mechanically adhered to the iron powder surface. Specifically, it can be obtained by mixing the iron powder produced in the second embodiment and the third embodiment. For this mixing, a container-rotating double cone mixer or a V-type mixer may be used, and the mixing conditions may be in accordance with the conventional methods.
このようにして得られた鉄粉の水浄化性能は、反応初期から高い分解性能を示すだけでなく、いずれのVOCともよく反応し、その効果の持続性にも優れている。 The water purification performance of the iron powder thus obtained not only shows high decomposition performance from the beginning of the reaction, but also reacts well with any VOC and has excellent sustainability.
［発明例１］
MBR鉱石およびコークスを層状に配した容器を、バッチ式箱型炉で、1150℃の粗還元をし、得られた粉末を、粉砕し、目開き：３mmの篩いでの篩分後、篩を通った粉末を0.2mmの篩いで篩分し、0.2mmの篩い上に残ったものを回収して0.2mm〜３mmに粒度調整することで、Ｃ：1.0mass％、Ｏ：2.5mass％を含有してなる粗還元鉄粉を得た。
この粗還元鉄粉を、水素中、850℃で還元し、粉砕して、Ｃ：0.11mass％、Ｏ：2.13mass％、比表面積：0.38m2/gの仕上げ還元鉄粉を得た。この鉄粉に、平均粒子径：１μmのNiを2.0mass％添加したものを１kg用ハイスピードミキサーで、回転数：2000rpmとして強撹拌し、地下水浄化用鉄粉を得た。
[Invention Example 1]
A container in which MBR ore and coke are arranged in layers is subjected to rough reduction at 1150 ° C in a batch-type box furnace. The passed powder is sieved with a 0.2 mm sieve, and what remains on the 0.2 mm sieve is recovered and adjusted to a particle size of 0.2 mm to 3 mm, containing C: 1.0 mass% and O: 2.5 mass% Thus obtained crude reduced iron powder was obtained.
The crude reduced iron powder was reduced in hydrogen at 850 ° C. and pulverized to obtain a finished reduced iron powder having C: 0.11 mass%, O: 2.13 mass%, and a specific surface area: 0.38 m 2 / g. To this iron powder, 2.0 mass% of Ni having an average particle diameter of 1 μm was added with a 1 kg high-speed mixer and vigorously stirred at a rotation speed of 2000 rpm to obtain iron powder for groundwater purification.
浄化性能は、反応速度定数の大きさで判断した。この反応速度定数は、以下に示す式のようにVOC濃度の擬一次反応と仮定して、反応時間とVOC濃度との片対数プロットによる傾きから求めた。また、一日ごとに、地下水浄化用鉄粉の入った容器の溶液を、決まった濃度のVOC溶液に入れ替え、翌日の濃度変化を読み取り、原点を通る線を引き、その傾きを読み取り、これを毎日繰り返した。
具体的には、TCE、cis-1,2-DCE、PCEを各100mg/L混合した溶液を、25ccのバイアルびんに入れ、上記地下水浄化用鉄粉を0.25ｇ添加したものを、ローテイターを用いて10rpmの回転数で回転させて、放置した。そして、１日ごとに上記溶液を入れ替え、回収した溶液の濃度を測定して、各VOCの反応速度定数（分解速度定数）を求めた。放置日数ごとの分解速度定数を、地下水浄化用鉄粉の、組成、仕上げ還元温度、比表面積と共に表１に示す。 Specifically, a solution in which 100 mg / L each of TCE, cis-1,2-DCE, and PCE is mixed is placed in a 25 cc vial and 0.25 g of the above groundwater purification iron powder is added using a rotator. And rotated at a rotation speed of 10 rpm. And the said solution was replaced every day, the density | concentration of the collect | recovered solution was measured, and the reaction rate constant (decomposition rate constant) of each VOC was calculated | required. Table 1 shows the decomposition rate constant for each standing period together with the composition, finishing reduction temperature, and specific surface area of the iron powder for groundwater purification.
［発明例２］
発明例１に用いたものと同じ物性の、MBR鉱石およびコークスを層状に配した容器をバッチ式箱型炉で、1150℃で粗還元し、これを粉砕し、0.2〜３mmの範囲に粒度調整し、Ｃ：1.0mass％、Ｏ：2.5mass％の粗還元鉄粉を得た。
これに平均粒子径１μmのNiを0.5mass％および2.0mass％添加し、混合したものを水素中、850℃で還元した。得られた地下水浄化用鉄粉は、Ni：0.5mass％、Ｃ：0.31mass％、Ｏ：1.78mass％、比表面積：0.35m2/g（発明例2-1）、および、Ni：2.0mass％、Ｃ：0.20mass％、Ｏ：2.07mass％、比表面積：0.31m2/g（発明例2-2）であった。
さらに、発明例１と同様の手法による評価を行い、その結果を表１に併記する。
[Invention Example 2]
A container with MBR ore and coke arranged in layers in the same physical properties as used in Invention Example 1 was roughly reduced at 1150 ° C. in a batch-type box furnace and pulverized to adjust the particle size within the range of 0.2 to 3 mm. Then, roughly reduced iron powder with C: 1.0 mass% and O: 2.5 mass% was obtained.
0.5 mass% and 2.0 mass% of Ni having an average particle diameter of 1 μm were added thereto, and the mixture was reduced at 850 ° C. in hydrogen. The obtained iron powder for purifying groundwater has Ni: 0.5 mass%, C: 0.31 mass%, O: 1.78 mass%, specific surface area: 0.35 m 2 / g (Invention Example 2-1), and Ni: 2.0 mass %, C: 0.20 mass%, O: 2.07 mass%, specific surface area: 0.31 m 2 / g (Invention Example 2-2).
Furthermore, evaluation by the same method as that of Invention Example 1 is performed, and the results are also shown in Table 1.
［発明例３］
発明例１で得られた地下水浄化用鉄粉と、発明例2-2で得られたNi：2.0mass％の地下水浄化用鉄粉とを、１：１の比で混合した地下水浄化用鉄粉を作製した。この地下水浄化用鉄粉の比表面積は、0.35m2/gであった。さらに、発明例１と同様の手法による評価を行い、その結果を表１に併記した。
[Invention Example 3]
Groundwater purification iron powder obtained by mixing the groundwater purification iron powder obtained in Invention Example 1 and Ni: 2.0 mass% groundwater purification iron powder obtained in Invention Example 2-2 at a ratio of 1: 1. Was made. The specific surface area of the groundwater purification iron powder was 0.35 m 2 / g. Furthermore, the evaluation was performed by the same method as in Invention Example 1, and the results are also shown in Table 1.
［発明例４］
発明例１に用いたものと同じ物性の、MBR鉱石およびコークスを層状に配した容器をバッチ式箱型炉で、1150℃で粗還元し、これを粉砕し、0.2〜３mmの範囲に粒度調整し、Ｃ：1.0mass％、Ｏ：2.5mass％の粗還元鉄粉を得た。これに平均粒子径１μmのNiを2.0mass％添加し、混合したものを水素中、600℃で還元した。得られた地下水浄化用鉄粉は、Ni：2.0mass％、Ｃ：0.70mass％、Ｏ：2.00mass％、比表面積：0.71m2/g、であった。さらに、発明例１と同様の手法による評価を行い、その結果を表１に併記した。
[Invention Example 4]
A container with MBR ore and coke arranged in layers in the same physical properties as used in Invention Example 1 was roughly reduced at 1150 ° C. in a batch-type box furnace and pulverized to adjust the particle size to a range of 0.2-3 mm Then, roughly reduced iron powder with C: 1.0 mass% and O: 2.5 mass% was obtained. To this, 2.0 mass% of Ni having an average particle diameter of 1 μm was added, and the mixture was reduced at 600 ° C. in hydrogen. The obtained iron powder for purifying groundwater was Ni: 2.0 mass%, C: 0.70 mass%, O: 2.00 mass%, and specific surface area: 0.71 m 2 / g. Furthermore, the evaluation was performed by the same method as in Invention Example 1, and the results are also shown in Table 1.
［発明例５］
発明例１に用いたものと同じ物性の、MBR鉱石およびコークスを層状に配した容器をバッチ式箱型炉で、1150℃で粗還元し、これを粉砕し、0.2〜３mmの範囲に粒度調整し、Ｃ：0.8mass％、Ｏ：2.7mass％の粗還元鉄粉を得た。この鉄粉に、平均粒子径：１μmのNiを2.0mass％添加したものを１kg用ハイスピードミキサーで、回転数：2000rpmとして強撹拌し、地下水浄化用鉄粉を得た。さらに、発明例１と同様の手法による評価を行い、その結果を表１に併記した。
[Invention Example 5]
A container with MBR ore and coke arranged in layers in the same physical properties as used in Invention Example 1 was roughly reduced at 1150 ° C. in a batch-type box furnace and pulverized to adjust the particle size within the range of 0.2 to 3 mm. C: 0.8 mass%, O: 2.7 mass% of coarse reduced iron powder was obtained. To this iron powder, 2.0 mass% of Ni having an average particle diameter of 1 μm was added with a 1 kg high-speed mixer and vigorously stirred at a rotation speed of 2000 rpm to obtain iron powder for groundwater purification. Furthermore, the evaluation was performed by the same method as in Invention Example 1, and the results are also shown in Table 1.
表１より、本発明を満足する発明例１〜５は、いずれも、良好な浄化性能を示していることがわかる。
［比較例１］
ミルスケールおよびコークスを層状に配した容器をバッチ式箱型炉で、1150℃で粗還元し、これを粉砕し、0.2〜３mmの範囲に粒度調整し、Ｃ：1.0mass％、Ｏ：2.5mass％の粗還元鉄粉を得た。
これをさらに、水素中、850℃で還元し、Ｃ：0.05mass%、Ｏ：0.20％、比表面積0.03ｍ2/ｇの鉄粉を得た。さらに、発明例１と同様の手法による評価を行い、その結果を表１に併記した。
同表より、比表面積が本発明を満足しない比較例１は、60日経過した時の反応速度定数であっても、発明例１〜５の１日経過の反応速度定数程度であることが分かる。
From Table 1, it can be seen that Invention Examples 1 to 5 satisfying the present invention all exhibit good purification performance.
[Comparative Example 1]
A container in which mill scale and coke are arranged in layers is roughly reduced at 1150 ° C. in a batch-type box furnace, pulverized and adjusted to a particle size of 0.2 to 3 mm, C: 1.0 mass%, O: 2.5 mass % Crude reduced iron powder was obtained.
This was further reduced in hydrogen at 850 ° C. to obtain iron powder having C: 0.05 mass%, O: 0.20%, and a specific surface area of 0.03 m 2 / g. Furthermore, the evaluation was performed by the same method as in Invention Example 1, and the results are also shown in Table 1.
From the same table, it can be seen that Comparative Example 1 whose specific surface area does not satisfy the present invention is about the same as the reaction rate constant after one day of Invention Examples 1 to 5, even when the reaction rate constant is after 60 days. .
［発明例６］
発明例３で用いた鉄粉をΦ：３cm、Ｈ：30cmのカラムに充填し、上向流にて、VOC汚染水を通水、通水前後のVOC濃度を測定した。詳細条件を以下に、また、カラム試験装置のイメージを図１に示す。また、時間経過毎の通水前後のVOC濃度を図２に示す。
鉄粉充填量：300ｇ
通水速度：53mL/ｈ、（ＳＶ：0.25ｈ-1）
VOC濃度
cis-1,2-DCE：7.5mg/L
TCE ：5.0mg/L
PCE ：0.5mg/L
[Invention Example 6]
The iron powder used in Invention Example 3 was packed in a column of Φ: 3 cm and H: 30 cm, and VOC-contaminated water was passed in an upward flow, and the VOC concentration before and after passing was measured. Detailed conditions are shown below, and an image of the column test apparatus is shown in FIG. Moreover, the VOC density | concentration before and after water flow for every time passage is shown in FIG.
Iron powder filling amount: 300g
Water flow rate: 53 mL / h, (SV: 0.25 h −1 )
VOC concentration
cis-1,2-DCE: 7.5mg / L
TCE: 5.0mg / L
PCE: 0.5mg / L
上記試験の結果、VOCに汚染された水を、本発明に従う鉄粉に通水することによって、VOC汚染水を長期間に亘って環境基準以下まで分解することができる。（環境基準は、cis-1,2-DCE：0.04mg/L、TCE：0.03mg/LおよびPCE：0.01mg/Lである。）
一方、同条件で、鉄粉を平均粒径が0.1mmのVOC分解用鉄粉に変えて試験したところ、VOCは環境基準以下まで分解するものの、26日の経過時点で鉄粉が固結し通水が不可能となってしまった。
以上より、本発明に従う鉄粉はカラム通水方式において、水処理用として長期間の使用が安定して可能であることがわかる。
As a result of the above test, by passing water contaminated with VOC through the iron powder according to the present invention, the VOC-contaminated water can be decomposed to an environmental standard or less over a long period of time. (Environmental standards are cis-1,2-DCE: 0.04 mg / L, TCE: 0.03 mg / L and PCE: 0.01 mg / L.)
On the other hand, under the same conditions, when iron powder was changed to iron powder for VOC decomposition with an average particle size of 0.1 mm, VOC decomposed to below the environmental standard, but the iron powder solidified when 26 days passed. Water has become impossible.
From the above, it can be seen that the iron powder according to the present invention can be stably used for a long period of time for water treatment in the column water flow system.
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