JP2011098300A - Cleaning agent for ground water and soil, and method of manufacturing the same - Google Patents
Cleaning agent for ground water and soil, and method of manufacturing the same Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 20
- 239000003673 groundwater Substances 0.000 title claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000012459 cleaning agent Substances 0.000 title abstract description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 108
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 67
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052742 iron Inorganic materials 0.000 claims abstract description 26
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052595 hematite Inorganic materials 0.000 claims abstract description 14
- 239000011019 hematite Substances 0.000 claims abstract description 14
- 150000002896 organic halogen compounds Chemical class 0.000 claims abstract description 11
- 239000013078 crystal Substances 0.000 claims abstract description 8
- 238000002441 X-ray diffraction Methods 0.000 claims abstract description 7
- 238000001228 spectrum Methods 0.000 claims abstract description 7
- 239000011246 composite particle Substances 0.000 claims abstract description 6
- 239000000843 powder Substances 0.000 claims description 16
- 238000000746 purification Methods 0.000 claims description 13
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 2
- 239000003599 detergent Substances 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 10
- 238000006243 chemical reaction Methods 0.000 description 13
- 239000002245 particle Substances 0.000 description 11
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 7
- 238000000354 decomposition reaction Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 230000009257 reactivity Effects 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 239000012298 atmosphere Substances 0.000 description 4
- 239000002131 composite material Substances 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- -1 halide compound Chemical class 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 150000004045 organic chlorine compounds Chemical class 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000004438 BET method Methods 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- YOBAEOGBNPPUQV-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe].[Fe] YOBAEOGBNPPUQV-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000012629 purifying agent Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001784 detoxification Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000003287 optical effect Effects 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
- 238000002360 preparation method Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000003115 supporting electrolyte Substances 0.000 description 1
- 229950011008 tetrachloroethylene Drugs 0.000 description 1
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- Processing Of Solid Wastes (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Powder Metallurgy (AREA)
Abstract
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及び土壌を浄化するための浄化剤に関する。 The present invention relates to a purification agent for purifying groundwater and soil contaminated with volatile organic halogen compounds and heavy metals.
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、過硫酸や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。 Methods for purifying soil and groundwater contaminated with volatile organic halogen compounds such as trichlorethylene and tetrachlorethylene in situ include reductive decomposition using iron powder and other metal powders, and oxidative decomposition using persulfuric acid and hydrogen peroxide. It has been put into practical use.
たとえば特許文献１では、地下水水位より深部に位置する土壌又は地下水水位より浅部に位置する土壌又は掘削した土壌であって、有機塩素系化合物で汚染された土壌に、鉄粉を添加・混合することにより、有機塩素系化合物を分解して前記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。 For example, in Patent Document 1, iron powder is added to and mixed with soil that is located deeper than the groundwater level, soil that is shallower than the groundwater level, or soil that has been excavated and contaminated with organochlorine compounds. Thus, a soil detoxification method for decomposing organochlorine compounds and purifying the soil is disclosed.
そして、本工法に適した鉄粉として、０．１質量％以上の炭素を含み且つ、５００ｃｍ２／ｇ以上の比表面積を有すると共に、５０質量％以上が１５０μｍのふるいを通過する粒度を有する鉄粉が記載されている。 And as iron powder suitable for this construction method, iron containing 0.1% by mass or more of carbon and having a specific surface area of 500 cm 2 / g or more, and 50% by mass or more of iron having a particle size passing through a 150 μm sieve. The powder is described.
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、分解対象物と接触確率を増やすために、鉄表面の面積が大きい、すなわち、比表面積が大きいものほど、分解速度は大きくなる。 In the reductive decomposition of an organic chlorine compound by iron powder, it is considered that the reaction proceeds by transferring electrons to the decomposition target on the surface of the iron powder. Therefore, in order to increase the probability of contact with an object to be decomposed, the decomposition rate increases as the area of the iron surface increases, that is, the specific surface area increases.
また、分解速度を大きくするために、比表面積を大きくするだけでなく、様々な手法が検討されている。たとえば、特許文献２には銅を含有する鉄粉が、特許文献３には、ほぼ球状の鉄粉の表面を覆うように銅が点在する銅被着鉄粉が、特許文献４には、Ｎｉを被着させた鉄粉が開示されている。何れの技術も、鉄粉表面に鉄より貴な金属を付着させることで、局部電池を形成し、鉄からの電子供給が起こりやすくしたものである。 In addition to increasing the specific surface area, various methods are being studied in order to increase the decomposition rate. For example, Patent Document 2 includes copper-containing iron powder, Patent Document 3 includes copper-coated iron powder interspersed with copper so as to cover the surface of a substantially spherical iron powder, and Patent Document 4 includes An iron powder coated with Ni is disclosed. In either technique, a local battery is formed by attaching a noble metal to iron on the surface of the iron powder, and electrons are easily supplied from the iron.
特許文献５および特許文献６には、α-Ｆｅとマグネタイトからなる鉄複合粒子粉末が、特許文献７には、酸化鉄を還元して得られる鉄粉粒子と非還元鉄粉粒子を混合してなる浄化剤が開示されている。 In Patent Document 5 and Patent Document 6, iron composite particle powder made of α-Fe and magnetite is mixed. In Patent Document 7, iron powder particles obtained by reducing iron oxide and non-reduced iron powder particles are mixed. A purifying agent is disclosed.
上記のように、鉄粉による有機ハロゲン化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は、（１）比表面積を大きくする、（２）鉄粉表面に第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 described above, in the reductive decomposition of an organic halide compound with iron powder, in order to increase the reaction rate, (1) the specific surface area is increased, (2) the second conductive material is added to the iron powder surface. A method such as depositing to form a local battery is taken.
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ためには、粒子を細かくすればよいが、金属粉末を細粒化すると、自然発火する可能性があり、その取り扱いには、細心の注意が必要となる。 In Patent Document 1, it is said that the specific surface area should simply be increased. Generally, in order to increase the specific surface area, the particles may be made finer, but if the metal powder is made finer, there is a possibility of spontaneous ignition. Yes, handling it requires great care.
特許文献２〜４に開示された貴金属を鉄粉表面に被着させる技術は、その製造方法が比較的容易ではあるが、元々、Ｎｉ、ＣｏやＣｕなど高価な金属を使用するため、浄化剤の価格が高くなる。また、昨今では、Ｎｉは、それ自体が環境汚染物質となる可能性も唱えられており、これら、貴金属を被着させた鉄粉を浄化用に使用することは、好ましくない。 The technique for depositing the noble metal on the surface of the iron powder disclosed in Patent Documents 2 to 4 is relatively easy to manufacture, but originally uses an expensive metal such as Ni, Co, Cu, etc. The price of will be higher. In recent years, it has been proposed that Ni itself becomes an environmental pollutant, and it is not preferable to use iron powder coated with a noble metal for purification.
特許文献５〜６では、鉄-マグネタイトの微粒子を浄化剤としているが、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、引き続き処理雰囲気を制御しながら徐酸化させ、鉄表面をマグネタイト化し、それにより発火を抑える効果を得ている。この方法では、酸化鉄の還元時に多量の水素を必要とし、また高温で処理することが必要となるため、製造コストがかかるし、一度還元した後に表面を酸化するため、製造プロセスも煩雑となっている。 In Patent Documents 5 to 6, iron-magnetite fine particles are used as a purifier, and the production method thereof uses iron oxide as a raw material, hydrogen reduction to produce fine iron powder, and then continuously controlling the treatment atmosphere. Slow oxidation is used to magnetize the iron surface, thereby suppressing ignition. This method requires a large amount of hydrogen at the time of reduction of iron oxide and requires treatment at a high temperature, which is expensive to manufacture and oxidizes the surface after reduction once, and the manufacturing process becomes complicated. ing.
また、特許文献７では、酸化鉄を還元して得られる鉄粉粒子と非還元鉄粉粒子を混合してなり、酸化鉄を還元して得られる鉄粉粒子が粒子の酸化状態の構成として、０価の鉄が５５から１００パーセント、酸化鉄（ Ｉ Ｉ ）が０から３０パーセント、三二酸化鉄が０から１５パーセント及び四三酸化鉄が０から４５パーセントであり、非還元鉄粉粒子が粒子の酸化状態の構成として、０価の鉄が１０から４０パーセント、酸化鉄（ Ｉ Ｉ ） が３０から７０パーセント、三二酸化鉄が０から１５パーセント及び四三酸化鉄が１０から３０パーセントであることを特徴とする土壌浄化剤が紹介されているが、酸化鉄を還元する工程と所定の鉄粉調製後、これらを混合する工程を含み製造プロセスが煩雑となっている。 Moreover, in patent document 7, iron powder particle | grains obtained by reduce | restoring iron oxide and non-reduced iron powder particle | grains are mixed, and the iron powder particle | grains obtained by reduce | restoring iron oxide are as a structure of the oxidation state of particle | grains, Zero-valent iron is 55 to 100 percent, iron oxide (I I) is 0 to 30 percent, iron sesquioxide is 0 to 15 percent, and iron tetroxide is 0 to 45 percent. Oxidation state composition is 10 to 40 percent of zero-valent iron, 30 to 70 percent of iron oxide (I I), 0 to 15 percent of iron sesquioxide, and 10 to 30 percent of iron tetroxide However, the manufacturing process is complicated, including a step of reducing iron oxide and a step of mixing these after preparation of predetermined iron powder.
本発明は、簡便な方法で製造できる土壌浄化化剤を提供することを目的とする。 An object of this invention is to provide the soil purification agent which can be manufactured by a simple method.
本発明によれば、ＮｉやＣｏなどの高価な金属を用いることなく、また、製造時に水素を用いることなく、安価に高い反応性を有する鉄−マグネタイト複合材を得ることができる。 According to the present invention, an iron-magnetite composite material having high reactivity can be obtained at low cost without using expensive metals such as Ni and Co, and without using hydrogen during production.
本発明の要旨は以下の通りである。 The gist of the present invention is as follows.
第一の発明は、鉄（Ｆｅ）とウスタイト（ＦｅＯ）と、マグネタイト（Ｆｅ３Ｏ４）と、ヘマタイト（Ｆｅ２Ｏ３）とからなる複合粒子であって、ＢＥＴ法比表面積が０．５〜５．０ｍ２／ｇ、Ｘ線回折スペクトルにおける鉄、ウスタイト、マグネタイト、ヘマタイトのピーク強度の総和に対するウスタイトとマグネタイトのピーク強度の和の比が、０．４〜１．０であり、且つ５０μｍ以上の結晶粒径を有する鉄を含むことを特徴とする揮発性有機ハロゲン化合物で汚染された地下水及び土壌の浄化剤である。 A first invention is a composite particle composed of iron (Fe), wustite (FeO), magnetite (Fe 3 O 4 ), and hematite (Fe 2 O 3 ), and has a BET specific surface area of 0.5. The ratio of the sum of the peak intensity of wustite and magnetite to the sum of the peak intensity of iron, wustite, magnetite and hematite in the X-ray diffraction spectrum of .about.5.0 m 2 / g is 0.4 to 1.0 and 50 μm A purification agent for groundwater and soil contaminated with a volatile organic halogen compound, characterized by containing iron having the above crystal grain size.
第二の発明は、酸化鉄粉と鉄粉とを（１：９９）〜（８０：２０）の質量割合で混合し、窒素雰囲気中で、４００〜９００℃で熱処理することを特徴とする第一の発明に記載の揮発性有機ハロゲン化合物で汚染された地下水及び土壌の浄化剤の製造方法である。 A second invention is characterized in that iron oxide powder and iron powder are mixed at a mass ratio of (1:99) to (80:20) and heat-treated at 400 to 900 ° C. in a nitrogen atmosphere. It is a manufacturing method of the ground water contaminated with the volatile organic halogen compound as described in one invention, and a soil purification agent.
第三の発明は、前記鉄粉を還元鉄粉とすることを特徴とする第二の発明に記載の揮発性有機ハロゲン化合物で汚染された地下水及び土壌の浄化剤の製造方法である。 A third invention is the method for producing a ground water and soil purifier contaminated with a volatile organic halogen compound according to the second invention, wherein the iron powder is reduced iron powder.
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や土壌を短時間で浄化できる浄化剤を提供できる。 ADVANTAGE OF THE INVENTION According to this invention, the purification agent which can purify | clean the groundwater and soil contaminated with the organic halogen compound etc. in a short time can be provided.
第１の実施の形態は、鉄（Ｆｅ）とウスタイト（ＦｅＯ）と、マグネタイト（Ｆｅ３Ｏ４）と、ヘマタイト（Ｆｅ２Ｏ３）とからなる複合粒子であって、ＢＥＴ比表面積が０．５〜５．０ｍ２／ｇ、Ｘ線回折スペクトルにおける鉄、ウスタイト、マグネタイト、ヘマタイトのピーク強度の総和に対するウスタイトとマグネタイトのピーク強度の和の比が、０．４〜１．０であり、且つ５０μｍ以上の結晶粒径を有する鉄を含むことを特徴とする揮発性有機ハロゲン化合物で汚染された地下水及び土壌の浄化剤である。 The first embodiment is a composite particle made of iron (Fe), wustite (FeO), magnetite (Fe 3 O 4 ), and hematite (Fe 2 O 3 ), and has a BET specific surface area of 0.1. 5 to 5.0 m 2 / g, the ratio of the sum of the peak intensities of wustite and magnetite to the sum of the peak intensities of iron, wustite, magnetite and hematite in the X-ray diffraction spectrum is 0.4 to 1.0, and It is a groundwater and soil purifier contaminated with a volatile organic halogen compound characterized by containing iron having a crystal grain size of 50 μm or more.
本発明における浄化剤は、鉄、ウスタイト、マグネタイトおよびヘマタイトの複合粒子である。純粋なα−Ｆｅは、その反応速度も十分大きいと考えられるが、一方で、常温空気中で放置すると、表面に酸化被膜ができ、反応性が劣化する。また、比表面積の大きな微粒子では、発熱、発火の危険性もあるため、保管上の注意が必要となる。 The purifying agent in the present invention is a composite particle of iron, wustite, magnetite and hematite. Pure α-Fe is considered to have a sufficiently high reaction rate. On the other hand, when it is left in air at room temperature, an oxide film is formed on the surface and the reactivity deteriorates. In addition, since fine particles with a large specific surface area have a risk of heat generation and ignition, precautions for storage are required.
本発明では、鉄粉と酸化鉄を、不活性雰囲気中で熱処理して、鉄粉表面を酸化すると同時に酸化鉄を還元させて、ウスタイト、マグネタイトおよびヘマタイトを生じさせる。このため、鉄粉自体は、酸化被膜で覆われているため、上記課題を解決できる。 In the present invention, iron powder and iron oxide are heat-treated in an inert atmosphere to oxidize the iron powder surface and simultaneously reduce iron oxide to produce wustite, magnetite, and hematite. For this reason, since iron powder itself is covered with the oxide film, the said subject can be solved.
金属鉄もしくは、その複合粉を用いた場合、その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、即ち、０．５ｍ２／ｇ以上とする必要がある。それ未満では、反応速度は小さくなり、浄化には適さないからである。 When metallic iron or a composite powder thereof is used, in order to increase the reaction rate, it is necessary to increase the specific surface area of the particles, that is, 0.5 m 2 / g or more. If it is less than that, the reaction rate becomes small and is not suitable for purification.
一方５．０ｍ２／ｇを越えるものでは、常温空気中でも激しく酸化反応が進行し、発熱、発火の危険性があるため、保管上好ましくない。 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 and ignition, which is not preferable for storage.
鉄、ウスタイト、マグネタイト、ヘマタイトの存在比には適正な値が存在する。すなわち、鉄、ウスタイト、マグネタイト、ヘマタイトのピーク強度の総和に対するウスタイト、マグネタイトのピーク強度の和の比が０．４〜１．０である。 There is an appropriate value for the abundance ratio of iron, wustite, magnetite, and hematite. That is, the ratio of the sum of the peak intensities of wustite and magnetite to the sum of the peak intensities of iron, wustite, magnetite and hematite is 0.4 to 1.0.
比が０．４未満では、反応速度が遅く、地下水や土壌の浄化には適さないからである。
一方、１．０超えでは、反応速度が速すぎるからである。
なおより好ましい範囲は、０．５〜１．０である。
If the ratio is less than 0.4, the reaction rate is slow and is not suitable for the purification of groundwater or soil.
On the other hand, if it exceeds 1.0, the reaction rate is too high.
A more preferable range is 0.5 to 1.0.
また、原料鉄粉をＨ２による仕上げ還元を行わない還元鉄粉とアトマイズ゛鉄粉とした場合、アトマイズ゛鉄粉は急冷されることにより、微細なマルテンサイト組織を有しており、低温の熱処理では５０μｍ以上の粒径にまでは粒成長しないし、反応性も十分ではない。従って、この場合は高温での熱処理を行うことにより、５０μｍ以上の結晶粒径を得られ、十分な反応速度を得ることができる。 In addition, when the raw iron powder is reduced iron powder and atomized iron powder that are not subjected to final reduction with H 2 , the atomized iron powder has a fine martensite structure due to being rapidly cooled, The heat treatment does not grow to a particle size of 50 μm or more, and the reactivity is not sufficient. Therefore, in this case, by performing heat treatment at a high temperature, a crystal grain size of 50 μm or more can be obtained, and a sufficient reaction rate can be obtained.
なお、結晶粒径が反応性に及ぼす影響は、定かではないが、より結晶性の高い（純度の高い）鉄の方が、反応性に富んでいると考えられる。 The influence of the crystal grain size on the reactivity is not clear, but iron with higher crystallinity (higher purity) is considered to be richer in reactivity.
第２の実施の形態は、上記浄化剤の製造方法に関する。 The second embodiment relates to a method for producing the purification agent.
本製造方法は、基本的には、不活性雰囲気中で熱処理を行い、酸化鉄を鉄粉で還元し、マグネタイトを発生させ、同時に鉄を酸化させて、マグネタイトもしくはウスタイトを得るものである。マグネタイトーＦｅ複合材を製造する方法としては、微粒子の酸化鉄を水素還元し、微粒子の鉄粉を得た後に、引き続き、酸化雰囲気で、鉄粉表面を緩やかに酸化させる方法などがあるが、本発明の製造方法であれば、比較的、簡単かつ低コストで、マグネタイト-Ｆｅ複合材とすることができる。なお、酸化鉄粉と鉄粉の質量割合は、（１：９９）〜（８０：２０）とする。本範囲を外れると所期の特性を得られない場合があるからである。 In this production method, heat treatment is basically performed in an inert atmosphere, iron oxide is reduced with iron powder to generate magnetite, and at the same time, iron is oxidized to obtain magnetite or wustite. As a method for producing a magnetite-Fe composite material, there is a method in which fine iron oxide is reduced by hydrogen to obtain fine iron powder and then the surface of the iron powder is gently oxidized in an oxidizing atmosphere. If it is the manufacturing method of this invention, it can be set as a magnetite-Fe composite material comparatively easily and at low cost. In addition, the mass ratio of iron oxide powder and iron powder shall be (1:99)-(80:20). This is because the desired characteristics may not be obtained if it is out of this range.
また、雰囲気温度を調整することで、ウスタイトも同時に出現できる。すなわち、その処理温度は、４００℃以上である。高温にすると反応速度は大きくなるが、同時に焼結が進み、比表面積が小さくなるからである。また、熱処理後の粉砕にも負荷がかかることとなるので熱処理温度は、９００℃以下である。 In addition, by adjusting the atmospheric temperature, wustite can also appear at the same time. That is, the processing temperature is 400 ° C. or higher. This is because when the temperature is increased, the reaction rate increases, but at the same time, the sintering proceeds and the specific surface area decreases. In addition, since a load is applied to the pulverization after the heat treatment, the heat treatment temperature is 900 ° C. or less.
ヘマタイト含有率が低すぎる場合には、X線回折スペクトル上、所望の強度比を得ることができない。また、高すぎる場合には、X線回折スペクトル上、所望の強度比を得られない、もしくは、所望の強度比を得るためには、長時間の熱処理が必要となるため経済的でない。 If the hematite content is too low, a desired intensity ratio cannot be obtained on the X-ray diffraction spectrum. On the other hand, if it is too high, a desired intensity ratio cannot be obtained on the X-ray diffraction spectrum, or a long-time heat treatment is required to obtain the desired intensity ratio, which is not economical.
ＪＦＥスチール社製の還元鉄粉Ｋ１００Ｔ及びアトマイズ゛鉄粉３００Ｒ、及びＪＦＥケミカル社製酸化鉄粉を用い、表１に示すような配合で鉄粉と酸化鉄粉を混合し、これを、管状炉で、Ｎ２を原料１Ｋｇにつき１Ｌ／ｍｉｎの割合で流通させ、毎分１０℃／ｍｉｎで所定温度まで昇温し、所定温度で１Ｈｒ熱処理を行ったものを浄化剤とした。 Using reduced iron powder K100T and atomized iron powder 300R manufactured by JFE Steel, and iron oxide powder manufactured by JFE Chemical Co., iron powder and iron oxide powder are mixed in the composition shown in Table 1, and this is added to a tubular furnace. Then, N 2 was circulated at a rate of 1 L / min per 1 kg of the raw material, heated to a predetermined temperature at 10 ° C./min per minute, and subjected to 1 Hr heat treatment at the predetermined temperature was used as a purifier.
得られた浄化剤は、ＢＥＴ法による比表面積測定を行い、また、α−Ｆｅ、ウスタイト、マグネタイト、ヘマタイトのピーク強度を測定し、α−Ｆｅ、ウスタイト、マグネタイト、ヘマタイトのピーク強度の総和に対するウスタイトとマグネタイトのピーク強度の和の比を求めた。各ピーク強度をＦｅ：鉄、Ｗ：ウスタイト、Ｍ：マグネタイト、Ｈ：ヘマタイトで表すと、その比は（Ｗ＋Ｍ）／（Ｆｅ＋Ｗ＋Ｍ＋Ｈ）と表される。 The obtained purification agent was subjected to specific surface area measurement by the BET method, and the peak intensity of α-Fe, wustite, magnetite and hematite was measured, and wustite relative to the sum of the peak intensity of α-Fe, wustite, magnetite and hematite. And the ratio of the sum of the peak intensities of magnetite. When each peak intensity is expressed as Fe: iron, W: wustite, M: magnetite, H: hematite, the ratio is expressed as (W + M) / (Fe + W + M + H).
また、得られた浄化剤を樹脂に埋込んで研磨し、エッチング後、光学顕微鏡により組織観察を行い、鉄中の結晶粒径を計測し、５０μｍ以上の結晶粒径の有無を判定した。 Further, the obtained cleaning agent was embedded in a resin and polished, and after etching, the structure was observed with an optical microscope, the crystal grain size in iron was measured, and the presence or absence of a crystal grain size of 50 μm or more was determined.
浄化実験は、５ｍｇ／Ｌのトリクロロエチレン水溶液５０ｍＬを１００ｍＬバイアル瓶に入れ、これに、浄化剤５ｇを添加した後に密栓し、２５℃、１８０ｒｐｍで、振盪し、所定時間後に、バイアル瓶ヘッドスペースのガス濃度を測定することで、トリクロロエチレン残存率（Ｃｔ／Ｃｉ）を求め、反応を擬一次反応とし、ｌｏｇ（Ｃｔ／Ｃｉ） ｖｓ 時間（Ｈｒ）の傾きより、その反応速度定数（Ｈｒ-1）を求めた。なお、Ｃｉはトリクロロエチレンの初期濃度を、Ｃｔは時間ｔにおけるトリクロロエチレンの濃度を意味する。また、上記トリクロロエチレン水溶液には、支持電解質として、Ｎａ２ＳＯ３とＣａＣＯ３を、それぞれ、８０ｍｇ／Ｌ、４０ｍｇ／Ｌに調整した。 In the purification experiment, 50 mL of a 5 mg / L trichlorethylene aqueous solution was placed in a 100 mL vial, and after adding 5 g of the cleaning agent, the cap was sealed, shaken at 25 ° C. and 180 rpm, and after a predetermined time, the gas in the vial headspace By measuring the concentration, the trichlorethylene residual rate (Ct / Ci) was obtained, the reaction was regarded as a pseudo-first order reaction, and the reaction rate constant (Hr −1 ) was determined from the slope of log (Ct / Ci) vs time (Hr). Asked. Ci means the initial concentration of trichlorethylene, and Ct means the concentration of trichlorethylene at time t. In the trichlorethylene aqueous solution, Na 2 SO 3 and CaCO 3 were adjusted to 80 mg / L and 40 mg / L, respectively, as supporting electrolytes.
表１から明らかなように、ＢＥＴ法比表面積が０．５〜５．０ｍ２／ｇ、Ｘ線回折スペクトルにおいてα−Ｆｅ、ウスタイト、マグネタイト、ヘマタイトのピーク強度の総和に対するウスタイトとマグネタイトのピーク強度の和の比が０．４〜１．０であり、かつ当該金属鉄の粒径が５０μｍ以上であれば、トリクロロエチレンの分解反応の反応速度定数ｋは０．０３Ｈｒ-1以上と、他のものに比較して大きいことがわかる。 As is apparent from Table 1, the BET method specific surface area is 0.5 to 5.0 m2 / g, and the peak intensity of wustite and magnetite with respect to the sum of the peak intensities of α-Fe, wustite, magnetite, and hematite in the X-ray diffraction spectrum. If the ratio of the sum is 0.4 to 1.0 and the particle diameter of the metallic iron is 50 μm or more, the reaction rate constant k of the decomposition reaction of trichlorethylene is 0.03 Hr −1 or more. It can be seen that it is large in comparison.
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