JP4012975B2 - Iron oxyhydroxide production method and iron oxyhydroxide adsorbent - Google Patents
Iron oxyhydroxide production method and iron oxyhydroxide adsorbent Download PDFInfo
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- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 title claims description 81
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 title claims description 80
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000003463 adsorbent Substances 0.000 title claims description 14
- 238000001035 drying Methods 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 22
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 19
- 229910052742 iron Inorganic materials 0.000 claims description 17
- 239000002244 precipitate Substances 0.000 claims description 14
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000001179 sorption measurement Methods 0.000 description 34
- 239000002245 particle Substances 0.000 description 30
- 229910002588 FeOOH Inorganic materials 0.000 description 24
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 24
- 229910052698 phosphorus Inorganic materials 0.000 description 24
- 239000011574 phosphorus Substances 0.000 description 24
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 19
- 239000000126 substance Substances 0.000 description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- -1 iron ion Chemical class 0.000 description 15
- 239000000243 solution Substances 0.000 description 15
- 238000011156 evaluation Methods 0.000 description 13
- 229910052739 hydrogen Inorganic materials 0.000 description 13
- 239000001257 hydrogen Substances 0.000 description 13
- 230000009931 harmful effect Effects 0.000 description 12
- 238000012360 testing method Methods 0.000 description 10
- 229940085991 phosphate ion Drugs 0.000 description 9
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 8
- 239000002585 base Substances 0.000 description 8
- 229910006540 α-FeOOH Inorganic materials 0.000 description 8
- 150000001450 anions Chemical class 0.000 description 7
- 239000013078 crystal Substances 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 125000000129 anionic group Chemical group 0.000 description 6
- 239000011148 porous material Substances 0.000 description 5
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 229940088597 hormone Drugs 0.000 description 4
- 239000005556 hormone Substances 0.000 description 4
- 235000014413 iron hydroxide Nutrition 0.000 description 4
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 4
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229910002553 FeIII Inorganic materials 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000000274 adsorptive effect Effects 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229960002089 ferrous chloride Drugs 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 229910052598 goethite Inorganic materials 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 2
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 2
- 239000010842 industrial wastewater Substances 0.000 description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 238000001028 reflection method Methods 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000000967 suction filtration Methods 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 125000004093 cyano group Chemical group *C#N 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 238000007561 laser diffraction method Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Substances [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- 150000003498 tellurium compounds Chemical class 0.000 description 1
- 230000001225 therapeutic effect Effects 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 229910003153 β-FeOOH Inorganic materials 0.000 description 1
- 229910006299 γ-FeOOH Inorganic materials 0.000 description 1
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- Compounds Of Iron (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Water Treatment By Sorption (AREA)
Description
本発明は、オキシ水酸化鉄の製造方法及びオキシ水酸化鉄吸着材に関する。さらに詳しくは、本発明は、工場廃水、排ガス中等のリン成分等の有害物質に対して優れた吸着能を有するオキシ水酸化鉄を有利に製造する方法、及びその方法により得られた吸着材に関するものである。 The present invention relates to a method for producing iron oxyhydroxide and an iron oxyhydroxide adsorbent. More specifically, the present invention relates to a method for advantageously producing iron oxyhydroxide having an excellent adsorbing ability for harmful substances such as phosphorus components in factory wastewater and exhaust gas, and an adsorbent obtained by the method. Is.
近年、科学技術の発展に伴って、多種多様な化学物質が製造、使用されている。このような化学物質は、人の健康や生態系に有害な影響を及ぼすものも数多く存在している。例えば、水処理の場合、有機もしくは無機のリン、フッ素、ヒ素、モリブデン、クロム、アンチモン、セレン、ホウ素、テルル、ベリリウム、シアン等が有害物質として知られている。また、気体処理の場合、排ガス中の硫化水素、メルカプタン、青酸、フッ化水素、塩化水素、ＳＯx、ＮＯx、その他、リン、ヒ素、アンチモン、硫黄、セレン、テルル化合物、シアノ化合物等が有害物質として知られている。
上記有害物質は、飲料水、水道水、ミネラルウォーター、治療用水、農業用水、工業廃水、及び空気中、排ガス中等に溶解、懸濁、乳化もしくは浮遊した状態で含まれている場合があり、これらの有害物質を分離、除去することが試みられている。
In recent years, with the development of science and technology, a wide variety of chemical substances are manufactured and used. Many of these chemical substances have harmful effects on human health and ecosystems. For example, in the case of water treatment, organic or inorganic phosphorus, fluorine, arsenic, molybdenum, chromium, antimony, selenium, boron, tellurium, beryllium, cyan and the like are known as harmful substances. In the case of gas treatment, hydrogen sulfide, mercaptan, hydrocyanic acid, hydrogen fluoride, hydrogen chloride, SO x , NO x , phosphorus, arsenic, antimony, sulfur, selenium, tellurium compounds, cyano compounds, etc. in the exhaust gas are harmful. Known as a substance.
The above hazardous substances may be contained in drinking water, tap water, mineral water, therapeutic water, agricultural water, industrial wastewater, and dissolved, suspended, emulsified or suspended in the air or exhaust gas. Attempts have been made to separate and remove the harmful substances.
従来、工業廃水等から有害な化学物質を吸着するための鉄系吸着材について、種々の提案がなされている。例えば、粒度５０μｍ以下の含水酸化鉄を２００〜５００℃で加熱し、含水酸化鉄中の結晶水を蒸発させ、細孔を０．１〜５０ｎｍ、比表面積１５〜２００ｍ2 ／ｇの含水酸化鉄（特許文献１参照）が提案されている。
しかしながら、特許文献１では、２００〜５００℃で加熱処理しているため、エネルギー消費が大きく、工業的に不利である。しかも、リン成分等の有害物質の吸着に必要な鉄系吸着材の吸着サイト（水素結合サイト）が、高温加熱処理により減少しているため、吸着力が十分でないという問題点があった。
Conventionally, various proposals have been made on iron-based adsorbents for adsorbing harmful chemical substances from industrial wastewater or the like. For example, hydrous iron oxide having a particle size of 50 μm or less is heated at 200 to 500 ° C. to evaporate crystal water in the hydrous iron oxide, and the pores are 0.1 to 50 nm and the specific surface area is 15 to 200 m 2 / g. (See Patent Document 1) has been proposed.
However, in patent document 1, since it heat-processes at 200-500 degreeC, energy consumption is large and it is industrially disadvantageous. In addition, since the adsorption sites (hydrogen bonding sites) of the iron-based adsorbent necessary for the adsorption of harmful substances such as phosphorus components are reduced by the high-temperature heat treatment, there is a problem that the adsorption power is not sufficient.
また、鉄イオン溶液にアルカリを加えてｐＨを３に調整し、低温で乾燥することによって得られた、非晶質の水酸化鉄系の沈殿生成物からなる陰イオン吸着材（特許文献２参照）が知られている。
しかしながら、ｐＨ３では1×１０-3ｍｏｌ／ｄｍ-3の３価の鉄イオンが残存し、水酸化鉄が安定に沈殿できない。しかも、特許文献２の方法では、本発明方法における（ｃ）工程の水処理及び乾燥処理を行っていないため、得られる吸着材は、比表面積が小さく吸着力も十分でないという問題点があった。
また、ＢＥＴ比表面積５０〜５００ｍ2／ｇの微粒子状オキシ水酸化鉄の凝集物の製造方法（特許文献３参照）も提案されている。
しかしながら、特許文献３のオキシ水酸化鉄は、粒子系がナノサイズで小さいため、反応性は優れているが、粒子の飛散や摩擦による発火等の恐れがあり、取り扱いに不便であり、さらに吸着物質の回収も困難であるという問題点があった。
このため、有害物質の吸着能が十分であり、かつ取り扱いの容易な吸着材の開発が望まれていた。
Further, an anion adsorbent comprising an amorphous iron hydroxide-based precipitation product obtained by adjusting the pH to 3 by adding an alkali to the iron ion solution and drying at a low temperature (see Patent Document 2) )It has been known.
However, at pH 3, trivalent iron ions of 1 × 10 −3 mol / dm −3 remain, and iron hydroxide cannot be precipitated stably. Moreover, in the method of Patent Document 2, since the water treatment and the drying treatment in the step (c) in the method of the present invention are not performed, the obtained adsorbent has a problem that the specific surface area is small and the adsorbing power is not sufficient.
In addition, a method for producing an aggregate of fine particle iron oxyhydroxide having a BET specific surface area of 50 to 500 m 2 / g (see Patent Document 3) has also been proposed.
However, the iron oxyhydroxide of Patent Document 3 is excellent in reactivity because the particle system is nano-sized and small, but there is a risk of ignition due to particle scattering or friction, which is inconvenient to handle, and further adsorbed. There was a problem that it was difficult to recover the substance.
For this reason, it has been desired to develop an adsorbent that has sufficient ability to adsorb harmful substances and is easy to handle.
本発明は、上記の現状に鑑み、工場廃水、排ガス中等のリン成分、環境ホルモン等の有害物質に対して優れた吸着能を有するオキシ水酸化鉄を有利に製造する方法、及びその方法により得られた吸着材を提供することを目的とする。 In view of the above situation, the present invention is a method for advantageously producing iron oxyhydroxide having an excellent adsorbing ability for harmful substances such as phosphorus components in factory wastewater, exhaust gas, and environmental hormones, and the method. It is an object to provide a prepared adsorbent.
本発明者らは、上記目的を達成すべく鋭意検討した結果、３価の鉄イオン含有溶液を出発原料として生成したオキシ水酸化鉄を含む沈殿物を低温乾燥し、更に水と接触させた後、再度低温乾燥することにより、上記目的を達成しうることを見出した。発明はかかる知見に基づいて完成したものである。
すなわち、本発明は、
（１）（ａ）３価の鉄イオン含有溶液に塩基を加え、ｐＨを３．３〜６に調整することにより、オキシ水酸化鉄を含む沈殿物を生成させる工程、
（ｂ）該沈殿物を１００℃以下の温度で乾燥することによってオキシ水酸化鉄を得る工程、及び
（ｃ）得られたオキシ水酸化鉄を水と接触させた後、１００℃以下の温度で乾燥する工程、を順次行うことを特徴とするオキシ水酸化鉄の製造方法、並びに
（２）前記（１）に記載の方法により得られたオキシ水酸化鉄を主成分とするオキシ水酸化鉄吸着材であって、ＢＥＴ比表面積が１００〜４００ｍ 2 ／ｇであり、オキシ水酸化鉄１ｋｇ当りの水酸基含有量が７〜３０ｍｏｌ−ＯＨ／ｋｇであるオキシ水酸化鉄吸着材、
を提供するものである。
As a result of intensive studies to achieve the above-mentioned object, the present inventors dried a precipitate containing iron oxyhydroxide produced using a trivalent iron ion-containing solution as a starting material at a low temperature and further contacted with water. The inventors have found that the above object can be achieved by drying at low temperature again. The invention has been completed based on such findings.
That is, the present invention
(1) (a) A step of generating a precipitate containing iron oxyhydroxide by adding a base to a trivalent iron ion-containing solution and adjusting the pH to 3.3 to 6,
(B) drying the precipitate at a temperature of 100 ° C. or less to obtain iron oxyhydroxide; and (c) contacting the obtained iron oxyhydroxide with water, and then at a temperature of 100 ° C. or less. A method for producing iron oxyhydroxide characterized by sequentially performing a drying step, and (2) iron oxyhydroxide adsorption mainly comprising iron oxyhydroxide obtained by the method described in (1) above An iron oxyhydroxide adsorbent having a BET specific surface area of 100 to 400 m 2 / g and a hydroxyl group content of 7 to 30 mol-OH / kg of iron oxyhydroxide ,
Is to provide.
本発明の製造方法によれば、リン成分、環境ホルモン等の有害物質に対して優れた吸着能を有するオキシ水酸化鉄を効率的に製造することができる。
また、本発明の製造方法により得られたオキシ水酸化鉄を主成分とする吸着材は、比表面積が大きく、かつ従来の５〜８倍の陰イオン吸着サイト（水素結合サイト）を有しているため、リン酸イオン等の陰イオン種に対して優れた吸着力を発揮し、浄水、排水又は気体浄化等の分野で好適に使用することができる。
また、本発明の吸着材は、再使用が容易であるため実用性が高く、吸着した陰イオン種を溶離させることにより、陰イオン種に含まれる元素を効率的に回収することができる。
According to the production method of the present invention, iron oxyhydroxide having an excellent adsorption ability for harmful substances such as phosphorus components and environmental hormones can be efficiently produced.
Further, the adsorbent mainly composed of iron oxyhydroxide obtained by the production method of the present invention has a large specific surface area and has 5 to 8 times the anion adsorption site (hydrogen bonding site) of the conventional one. Therefore, it exhibits an excellent adsorptive power for anionic species such as phosphate ions, and can be suitably used in fields such as water purification, drainage or gas purification.
The adsorbent of the present invention is highly practical because it can be easily reused, and the elements contained in the anionic species can be efficiently recovered by eluting the adsorbed anionic species.
本発明のオキシ水酸化鉄の製造方法は、（ａ）３価の鉄イオン含有溶液に塩基を加え、ｐＨを３．３〜６に調整することにより、オキシ水酸化鉄を含む沈殿物を生成させる工程、
（ｂ）該沈殿物を１００℃以下の温度で乾燥することによってオキシ水酸化鉄を得る工程、及び
（ｃ）得られたオキシ水酸化鉄を水と接触させた後、１００℃以下の温度で乾燥する工程、を順次行うが、中でも（ｃ）工程が大きな特徴である。
In the method for producing iron oxyhydroxide of the present invention, (a) a base is added to a trivalent iron ion-containing solution, and the pH is adjusted to 3.3 to 6, thereby generating a precipitate containing iron oxyhydroxide. The process of
(B) drying the precipitate at a temperature of 100 ° C. or less to obtain iron oxyhydroxide; and (c) contacting the obtained iron oxyhydroxide with water, and then at a temperature of 100 ° C. or less. The drying process is sequentially performed, and the (c) process is a significant feature.
本発明方法の（ａ）工程において、原料溶液である３価の鉄イオン含有溶液としては、塩化第二鉄〔ＦｅＣｌ3〕、硫酸第二鉄〔Ｆｅ2（ＳＯ4）3〕、硝酸第二鉄〔Ｆｅ（ＮＯ3）3〕等の第二鉄化合物を含有する溶液が挙げられる。これらの中では、反応性等の観点から、塩化第二鉄〔ＦｅＣｌ3〕の水溶液が好ましい。 In the step (a) of the method of the present invention, ferric chloride [FeCl 3 ], ferric sulfate [Fe 2 (SO 4 ) 3 ], ferric nitrate are used as the trivalent iron ion-containing solution as the raw material solution. A solution containing a ferric compound such as iron [Fe (NO 3 ) 3 ] may be mentioned. Among these, an aqueous solution of ferric chloride [FeCl 3 ] is preferable from the viewpoint of reactivity and the like.
塩基は、３価の鉄イオン含有溶液を中和し、ｐＨを調整して、オキシ水酸化鉄を含む沈殿生成物を生成させるために使用する。塩基としては、ＮａＯＨ、ＫＯＨ、Ｎａ2ＣＯ3、Ｋ2ＣＯ3、ＣａＯ、Ｃａ（ＯＨ）2、ＣａＣＯ3、ＮＨ3、ＮＨ4ＯＨ、ＭｇＯ、ＭｇＣＯ3等を使用することができる。これらの中では、特に水酸化ナトリウム（ＮａＯＨ）が好ましい。 The base is used to neutralize the trivalent iron ion-containing solution and adjust the pH to produce a precipitated product containing iron oxyhydroxide. As the base, NaOH, KOH, Na 2 CO 3 , K 2 CO 3 , CaO, Ca (OH) 2 , CaCO 3 , NH 3 , NH 4 OH, MgO, MgCO 3 or the like can be used. Of these, sodium hydroxide (NaOH) is particularly preferable.
用いる３価の鉄イオン含有溶液及び塩基の濃度に特に制限はない。塩基の反応制御の容易さの観点から、３価の鉄イオン含有溶液の濃度は０．０１〜５ｍｏｌ／Ｌが好ましく、０．０５〜３ｍｏｌ／Ｌが更に好ましい。また、塩基の濃度は０．１〜１０モル／Ｌが好ましく、１〜５モル／Ｌが更に好ましい。
ｐＨは３．３〜６に調整する必要がある。ｐＨが３．３未満、例えばｐＨ３では、オキシ水酸化鉄の結晶生成の初期段階なので、1×１０-3ｍｏｌ／ｄｍ-3の３価の鉄イオンが残存し、安定状態で沈殿物を生成することが困難である。ｐＨを３．３とすることによって、３価の鉄イオンの残存濃度は1×１０-4ｍｏｌ／ｄｍ-3となり、安定的に水酸化鉄が沈殿できる。また、ｐＨ７付近では塩化第一鉄が沈殿する。従って、適切な水素結合サイトを有するオキシ水酸化鉄を高純度で安定に生成させる観点から、ｐＨは好ましくは３．５〜５．５、更に好ましくは３．７〜５．３とする。
There are no particular limitations on the concentration of the trivalent iron ion-containing solution and the base used. In light of ease of reaction control of the base, the concentration of the trivalent iron ion-containing solution is preferably 0.01 to 5 mol / L, and more preferably 0.05 to 3 mol / L. The concentration of the base is preferably 0.1 to 10 mol / L, more preferably 1 to 5 mol / L.
The pH needs to be adjusted to 3.3-6. When the pH is less than 3.3, for example, pH 3, since it is an initial stage of iron oxyhydroxide crystal formation, 1 × 10 −3 mol / dm −3 trivalent iron ions remain and precipitates are formed in a stable state. Difficult to do. By adjusting the pH to 3.3, the residual concentration of trivalent iron ions becomes 1 × 10 −4 mol / dm −3 and iron hydroxide can be stably precipitated. Moreover, in the vicinity of pH 7, ferrous chloride precipitates. Therefore, from the viewpoint of stably producing high-purity iron oxyhydroxide having an appropriate hydrogen bonding site, the pH is preferably 3.5 to 5.5, more preferably 3.7 to 5.3.
（ａ）工程で得られた沈殿物は吸引濾過等により濾別し、（ｂ）工程に供する。
（ｂ）工程においては、その沈殿物を１００℃以下の温度で乾燥する。温度が１００℃を超えると乾燥は速いが、陰イオンの吸着サイト（水素結合サイト）を適切に残すよう制御することが困難となる。また、温度が低すぎると乾燥に時間がかかりすぎ、実用的でない場合がある。このため、乾燥温度は、好ましくは２０〜８０℃、更に好ましくは３０〜７０℃、特に好ましくは４０℃以上６０℃未満である。乾燥は、空気中、真空中、不活性ガス中のいずれでもよいが、真空条件下で行うことが好ましい。乾燥時間は特に制限はなく、通常２時間〜２日間、好ましくは５時間〜２４時間である。
本発明の（ｂ）工程においては、高温度での乾燥処理がないので、オキシ水酸化鉄の粒子間焼結が起こらない。このため、（ｂ）工程により得られたオキシ水酸化鉄は、３０〜３００ｍ2／ｇ、特に４０〜２００ｍ2／ｇのＢＥＴ比表面積を有する。
The precipitate obtained in the step (a) is separated by suction filtration or the like, and used for the step (b).
In the step (b), the precipitate is dried at a temperature of 100 ° C. or lower. When the temperature exceeds 100 ° C., the drying is fast, but it becomes difficult to control the adsorption site (hydrogen bonding site) of anions appropriately. If the temperature is too low, drying takes too much time, which may not be practical. For this reason, drying temperature becomes like this. Preferably it is 20-80 degreeC, More preferably, it is 30-70 degreeC, Most preferably, it is 40 degreeC or more and less than 60 degreeC. Drying may be performed in air, vacuum, or inert gas, but is preferably performed under vacuum conditions. The drying time is not particularly limited, and is usually 2 hours to 2 days, preferably 5 hours to 24 hours.
In the step (b) of the present invention, since there is no drying treatment at a high temperature, interparticle sintering of iron oxyhydroxide does not occur. Therefore, (b) iron oxyhydroxide obtained in the step has a 30~300m 2 / g, BET specific surface area of the particular 40 to 200 m 2 / g.
また、（ｂ）工程により得られたオキシ水酸化鉄は、水素結合サイト（陰イオン吸着サイト）を大量に含有し、オキシ水酸化鉄１ｋｇ当りの水酸基含有量で３ｍｏｌ−ＯＨ／ｋｇ以上、好ましくは５〜２０ｍｏｌ−ＯＨ／ｋｇ、更に好ましくは７〜３０ｍｏｌ−ＯＨ／ｋｇである。
なお、オキシ水酸化鉄の水酸基含有量は、フーリエ変換赤外分光光度計（拡散反射法）を用いて、ＦｅＯＯＨの Ｏ−Ｈの伸縮状態を測定し、Russel et al., Nature 1974, 248, 220-221からＦｅＯＯＨのピークを３１３０ｃｍ-1及び３４２０ｃｍ-1として、Miura et al., Am. Chem. Soc., Fuel Chem., 1999, 44 (3), 642-646に基づいて算出し、決定することができる。
Further, the iron oxyhydroxide obtained in the step (b) contains a large amount of hydrogen bonding sites (anion adsorption sites), and the hydroxyl group content per kg of iron oxyhydroxide is 3 mol-OH / kg or more, preferably Is 5 to 20 mol-OH / kg, more preferably 7 to 30 mol-OH / kg.
The hydroxyl group content of iron oxyhydroxide was determined by measuring the stretched state of O—H of FeOOH using a Fourier transform infrared spectrophotometer (diffuse reflection method), and Russel et al., Nature 1974, 248, Calculated based on Miura et al., Am. Chem. Soc., Fuel Chem., 1999, 44 (3), 642-646, with FeOOH peaks from 220-221 as 3130 cm -1 and 3420 cm -1 can do.
（ｂ）工程により得られたオキシ水酸化鉄は針状結晶であり、幅が１０〜５００ｎｍ、好ましくは５０〜２００ｎｍであり、長さ／幅の比（Ｌ／Ｄ）は、通常５／１〜５０／１、好ましくは５／１〜２０／１である。
オキシ水酸化鉄は針状結晶であるが、凝集して凝集体粒子となっている。オキシ水酸化鉄の凝集体粒子としての平均粒子径は１００〜３００μｍ、好ましくは１５０〜２５０μｍである。
ここで、平均粒子径とは、レーザー回折／散乱式粒度分布計（例えば、株式会社堀場製作所、ＬＡ−９２０）を用いて、レーザー回折／散乱法で測定された体積基準粒度分布から算出されるメジアン径を意味する。
The iron oxyhydroxide obtained by the step (b) is a needle-like crystal, the width is 10 to 500 nm, preferably 50 to 200 nm, and the length / width ratio (L / D) is usually 5/1. -50/1, preferably 5 / 1-20 / 1.
Iron oxyhydroxide is a needle-like crystal, but is aggregated into aggregate particles. The average particle diameter of the iron oxyhydroxide aggregate particles is 100 to 300 μm, preferably 150 to 250 μm.
Here, the average particle size is calculated from a volume-based particle size distribution measured by a laser diffraction / scattering method using a laser diffraction / scattering particle size distribution analyzer (for example, Horiba, Ltd., LA-920). Mean median diameter.
本発明方法の（ｃ）工程においては、（ｂ）工程で得られたオキシ水酸化鉄を水と接触させた後、１００℃以下の温度で乾燥する。
温度が１００℃を超えると乾燥は速いが、水素結合サイト（陰イオン吸着サイト）を適切に残すよう制御することが困難となる。また、温度が低すぎると乾燥に時間がかかりすぎ、実用的でない場合がある。このため、乾燥温度は、好ましくは２０〜８０℃、更に好ましくは３０〜７０℃、特に好ましくは４０℃以上６０℃未満である。乾燥は、空気中、真空中、不活性ガス中のいずれでもよいが、真空条件下で行うことが好ましい。乾燥時間は特に制限はなく、通常２時間〜２日間、好ましくは５時間〜２４時間である。
（ｃ）工程における処理により、得られるオキシ水酸化鉄１ｋｇ当りの水酸基含有量（オキシ水酸化鉄の吸着サイト）は、３ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨ以上、好ましくは５〜２０ｍｏｌ−ＯＨ／ｋｇ、更に好ましくは７〜３０ｍｏｌ−ＯＨ／ｋｇのままで大きく変化しない。しかし、ＢＥＴ比表面積は、１．２倍以上、好適条件では１．５〜２．５倍増大する。その結果、ＢＥＴ法による比表面積は、好ましくは１００〜４００ｍ2／ｇ、更に好ましくは１２０〜３５０ｍ2／ｇ、特に好ましくは１５０〜３００ｍ2／ｇとなる。
本発明の（ｃ）工程においては、高温度での乾燥処理がないので粒子間焼結がなく、増大したＢＥＴ比表面積が減少することはない。
凝集体粒子としての平均粒子径は、８０〜３００μｍ、好ましくは１００〜２００μｍである。
In step (c) of the method of the present invention, the iron oxyhydroxide obtained in step (b) is brought into contact with water and then dried at a temperature of 100 ° C. or lower.
When the temperature exceeds 100 ° C., drying is fast, but it is difficult to control the hydrogen bonding sites (anion adsorption sites) to remain appropriately. If the temperature is too low, drying takes too much time, which may not be practical. For this reason, drying temperature becomes like this. Preferably it is 20-80 degreeC, More preferably, it is 30-70 degreeC, Most preferably, it is 40 degreeC or more and less than 60 degreeC. Drying may be performed in air, vacuum, or inert gas, but is preferably performed under vacuum conditions. The drying time is not particularly limited, and is usually 2 hours to 2 days, preferably 5 hours to 24 hours.
The hydroxyl group content (iron oxyhydroxide adsorption site) per kg of iron oxyhydroxide obtained by the treatment in the step (c) is 3 mol-OH / kg-FeOOH or more, preferably 5 to 20 mol-OH / kg, More preferably, it remains 7 to 30 mol-OH / kg and does not change greatly. However, the BET specific surface area increases by 1.2 times or more, and 1.5 to 2.5 times under suitable conditions. As a result, the specific surface area measured by the BET method, preferably 100 to 400 m 2 / g, more preferably 120~350m 2 / g, particularly preferably a 150 to 300 m 2 / g.
In the step (c) of the present invention, since there is no drying treatment at a high temperature, there is no interparticle sintering, and the increased BET specific surface area does not decrease.
The average particle diameter as the aggregate particles is 80 to 300 μm, preferably 100 to 200 μm.
（ｃ）工程の水処理による比表面積増大のメカニズムについては、次の（１）、（２）が考えられる。
（１）３価の鉄イオン含有溶液に水酸化ナトリウム等の塩基を添加するので、ＦｅＯＯＨ凝集体中に不純物としてＮａＣｌの結晶がナノサイズで生成する。これが水と接触することによってＮａＣｌが溶解し、ＮａＣｌが溶解した部分は細孔になり、比表面積増大に繋がると考えられる。
（２）ＦｅＯＯＨ製造過程でｐＨを３．３〜６に調整するため、ＦｅＯＯＨを完全に結晶化するには水酸基（ＯＨ）が不足状態にあり、その状態のまま１００℃以下という低温で乾燥することでさらに水酸基が不足状態となる。その状態でオキシ水酸化鉄が水と接触すると急激な吸水が起こり、その吸水によってＦｅＯＯＨの結晶格子間が緩むと考えられる。
The following (1) and (2) can be considered about the mechanism of the specific surface area increase by the water treatment of (c) process.
(1) Since a base such as sodium hydroxide is added to the trivalent iron ion-containing solution, NaCl crystals are produced in nano-size as impurities in the FeOOH aggregate. When this comes into contact with water, NaCl is dissolved, and the portion where NaCl is dissolved becomes pores, which is thought to increase the specific surface area.
(2) Since the pH is adjusted to 3.3 to 6 in the production process of FeOOH, there is insufficient hydroxyl group (OH) to completely crystallize FeOOH, and it is dried at a low temperature of 100 ° C. or lower in that state. As a result, the hydroxyl group becomes insufficient. In this state, when iron oxyhydroxide comes into contact with water, rapid water absorption occurs, and it is considered that the crystal lattice of FeOOH is loosened by the water absorption.
本発明方法においては、（ａ）〜（ｃ）の各工程の条件を適宜調整することにより、ＢＥＴ比表面積、水酸基含有量、単独粒子の平均粒子径及び微粒子凝集体の平均粒子径の異なるオキシ水酸化鉄を製造することができる。 In the method of the present invention, by appropriately adjusting the conditions of the steps (a) to (c), the BET specific surface area, the hydroxyl group content, the average particle size of single particles, and the average particle size of fine particle aggregates are different. Iron hydroxide can be produced.
オキシ水酸化鉄には、α−ＦｅＯＯＨ（ゲータイト）、β−ＦｅＯＯＨ（アカゲナイト）、γ−ＦｅＯＯＨ（レピドクロサイト）の３種類があるが、本発明方法によるオキシ水酸化鉄はα−ＦｅＯＯＨに近いが、１００％完全なα−ＦｅＯＯＨ（ゲータイト）ではないと考えられる。本発明方法によるオキシ水酸化鉄は、α−ＦｅＯＯＨに近い非晶質ＦｅＯＯＨの微粒子であり、これが大きな凝集体となっており、光沢のある黒色粒子の形態となっている。その凝集体は無数の細孔を保有する。粒子の平均細孔径は、好ましくは０．１〜５．０ｎｍ，更に好ましくは０．５〜１．５ｎｍである。 There are three types of iron oxyhydroxides, α-FeOOH (goethite), β-FeOOH (akagenite), and γ-FeOOH (repidocrocite), but the iron oxyhydroxide by the method of the present invention is close to α-FeOOH. However, it is considered that it is not 100% perfect α-FeOOH (goethite). The iron oxyhydroxide by the method of the present invention is amorphous FeOOH fine particles close to α-FeOOH, which are large aggregates, and are in the form of glossy black particles. The aggregate has innumerable pores. The average pore diameter of the particles is preferably 0.1 to 5.0 nm, more preferably 0.5 to 1.5 nm.
本発明のオキシ水酸化鉄の結晶構造は基本的には斜方晶であり、ＦｅＯ6８面体はＦｅIIIイオンに３つＯ2-と３つのＯＨ-が配位している。このＦｅIIIイオンに配位したＯＨ-のＯ−Ｈの伸縮が、フーリエ変換赤外分光光度計（ＦＴＩＲ）で測定したときに特徴的なスペクトルとして得ることができる。
すなわち、本発明のＦｅＯＯＨのＦＴＩＲスペクトルピークは、Ｏ−Ｈ伸縮を示す３４２０ｃｍ-1に大きなピークがあり、弱い水素結合のＯＨ基を大量に含有していることが特徴である。ＦＴＩＲスペクトルにおけるこの３４２０ｃｍ-1のピークのＯＨ-が、水素結合サイトとして、リン酸イオン等の陰イオン及び環境ホルモンの吸着において大きな役割を果す。
The crystal structure of the iron oxyhydroxide of the present invention is basically orthorhombic, and the FeO 6 octahedron is coordinated with three O 2− and three OH − atoms on the FeIII ion. The stretching of OH − OH coordinated to FeIII ions can be obtained as a characteristic spectrum when measured with a Fourier transform infrared spectrophotometer (FTIR).
That is, the FTIR spectrum peak of FeOOH of the present invention has a large peak at 3420 cm −1 exhibiting O—H stretching, and is characterized by containing a large amount of weak hydrogen-bonded OH groups. This 3420 cm −1 peak OH − in the FTIR spectrum plays a major role in the adsorption of anions such as phosphate ions and environmental hormones as hydrogen bonding sites.
本発明のオキシ水酸化鉄を用いて、水中のリン成分、環境ホルモン等の有害物質を除去する場合、これを充填塔（槽）に充填し、通水する方法で行うことができる。この場合、凝集体粒子の平均細孔径、平均粒子径、ＢＥＴ比表面積等は、吸着除去しようとする有害物質の捕捉に適した値のものを使用する。一般的には、取り扱い性、吸着性、吸着物質の回収性の観点から、平均粒子径が０．２〜１００ｍｍ、好ましくは０．５〜５０ｍｍ、更に好ましくは１〜３０ｍｍの凝集体で多孔質のオキシ水酸化鉄凝集体が適当である。 When removing harmful substances such as phosphorus components and environmental hormones in water using the iron oxyhydroxide of the present invention, it can be carried out by filling the packed tower (tank) and passing water. In this case, the average pore diameter, average particle diameter, BET specific surface area, etc. of the aggregate particles are those suitable for capturing harmful substances to be adsorbed and removed. In general, from the viewpoint of handleability, adsorptivity, and recoverability of adsorbed substances, the aggregate is porous with an average particle diameter of 0.2 to 100 mm, preferably 0.5 to 50 mm, more preferably 1 to 30 mm. The iron oxyhydroxide aggregates are suitable.
本発明の製造方法で得られたオキシ水酸化鉄は、非表面積が大きく、かつ従来の５〜８倍の陰イオン吸着サイト（水素結合サイト）を有しているため、陰イオン種に対して優れた吸着力を発揮し、浄水又は気体浄化等の分野で好適に使用することができる。また、再使用が容易であるため実用性が高く、吸着したリン酸イオン等を効率的に分離、回収することができる。 The iron oxyhydroxide obtained by the production method of the present invention has a large non-surface area and has an anion adsorption site (hydrogen bonding site) 5 to 8 times that of the conventional one. It exhibits excellent adsorptive power and can be suitably used in fields such as water purification or gas purification. Moreover, since it can be easily reused, it is highly practical, and the adsorbed phosphate ions and the like can be efficiently separated and recovered.
次に、本発明を実施例によってさらに詳細に説明するが、本発明はこれによりなんら限定されるものではない。
（オキシ水酸化鉄の製造）
実施例１
塩化第二鉄（ＦｅＣｌ3・６Ｈ2Ｏ）を０．１ｍｏｌ／Ｌとなるように水に溶解し、室温で撹拌しながら、濃度２モル/ LのＮａＯＨ溶液を添加して溶液全体のｐＨを４に調整した。溶液中に生じた沈殿生成物を２４時間静置し、吸引濾過して、沈殿物を得た。この沈殿物を５０℃で４８時間、定温乾燥器中で乾燥してＦｅＯＯＨを得た。
得られたＦｅＯＯＨのＢＥＴ比表面積は５０．６ｍ2／ｇ、水酸基含有量は１２．７８ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨ、凝集体粒子としての平均粒子径は、２００μｍであった。
このオキシ水酸化鉄を、パルプ濃度（水重量と乾燥オキシ水酸化鉄との重量比）が５％となるように純水中に投入し、室温で５分間撹拌した。撹拌後に吸引濾過して、オキシ水酸化鉄を得た。得られたオキシ水酸化鉄を５５℃で２４時間乾燥処理した。
得られたオキシ水酸化鉄のＢＥＴ比表面積は２１８．６ｍ2／ｇ、水酸基含有量は１２．８ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨ、凝集体粒子としての平均粒子径は、１３７．５μｍであった。
なお、測定条件は次のとおりである。
（１）ＢＥＴ比表面積
日本ベル株式会社製、ＢＥＴ比表面積測定装置、型式BELSORP-miniを用いて測定した。
（２）水酸基含有量
日本電子株式会社製、フーリエ変換赤外分光光度計（ＦＴＩＲ）、型式ＳＰＸ60（拡散反射法）を用いて、ＦｅＯＯＨの水素結合サイトとして、 Ｏ−Ｈの伸縮状態を測定した。Russel et al., Nature 1974, 248, 220-221からＦｅＯＯＨのピークを３１３０ｃｍ-1及び３４２０ｃｍ-1として、水酸基含有量をMiura et al., Am. Chem. Soc., Fuel Chem., 1999, 44 (3), 642-646に基づいて算出し、決定した。
（３）平均粒子径
株式会社堀場製作所製、レーザー回折／散乱式粒度分布計、型式ＬＡ-920を用いて測定された体積基準粒度分布からメジアン径を算出した。
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this.
(Manufacture of iron oxyhydroxide)
Example 1
Dissolve ferric chloride (FeCl 3 · 6H 2 O) in water to a concentration of 0.1 mol / L. While stirring at room temperature, add a 2 mol / L NaOH solution to adjust the pH of the entire solution. 4 was adjusted. The precipitated product generated in the solution was allowed to stand for 24 hours and suction filtered to obtain a precipitate. This precipitate was dried in a constant temperature dryer at 50 ° C. for 48 hours to obtain FeOOH.
The obtained FeOOH had a BET specific surface area of 50.6 m 2 / g, a hydroxyl group content of 12.78 mol-OH / kg-FeOOH, and an average particle size as aggregate particles of 200 μm.
This iron oxyhydroxide was put into pure water so that the pulp concentration (weight ratio of water weight to dry iron oxyhydroxide) was 5%, and stirred at room temperature for 5 minutes. After stirring, suction filtration was performed to obtain iron oxyhydroxide. The obtained iron oxyhydroxide was dried at 55 ° C. for 24 hours.
The obtained iron oxyhydroxide had a BET specific surface area of 218.6 m 2 / g, a hydroxyl group content of 12.8 mol-OH / kg-FeOOH, and an average particle size as aggregate particles of 137.5 μm.
The measurement conditions are as follows.
(1) BET specific surface area It measured using Nippon Belle Co., Ltd. make, BET specific surface area measuring apparatus, and model BELSORP-mini.
(2) Hydroxyl content Using a Fourier transform infrared spectrophotometer (FTIR) manufactured by JEOL Ltd., model SPX60 (diffuse reflection method), the stretched state of OH was measured as a hydrogen bonding site of FeOOH. . Russel et al., Nature 1974, 248, the peaks of FeOOH as 3130Cm -1 and 3420cm -1 of 220-221, a hydroxyl group content Miura et al., Am. Chem . Soc., Fuel Chem., 1999, 44 (3), calculated based on 642-646.
(3) Average particle size The median diameter was calculated from the volume-based particle size distribution measured using a laser diffraction / scattering particle size distribution meter, model LA-920, manufactured by HORIBA, Ltd.
実施例２〜１０
実施例１において、ｐＨ及び乾燥条件を、第１表に記載した条件としたこと以外は、実施例１と同様に行った。結果を第１表に示す。
なお、真空乾燥の場合は、ゲージ圧０．１ＭＰａで行った。
Examples 2-10
In Example 1, it carried out like Example 1 except having set pH and drying conditions to the conditions described in Table 1. The results are shown in Table 1.
In the case of vacuum drying, the gauge pressure was 0.1 MPa.
比較例１
市販試薬のオキシ水酸化鉄（α−ＦｅＯＯＨ、ナカライテスク株式会社製、ＢＥＴ比表面積１０．８ｍ2／ｇ）を２３０℃で２時間加熱処理した。得られたオキシ水酸化鉄のＢＥＴ比表面積は１７０ｍ2／ｇ、水酸基含有量は３ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨ、凝集体粒子としての平均粒子径は、１８９μｍであった。
Comparative Example 1
Commercially available iron oxyhydroxide (α-FeOOH, manufactured by Nacalai Tesque, Inc., BET specific surface area 10.8 m 2 / g) was heat-treated at 230 ° C. for 2 hours. The obtained iron oxyhydroxide had a BET specific surface area of 170 m 2 / g, a hydroxyl group content of 3 mol-OH / kg-FeOOH, and an average particle size as aggregate particles of 189 μm.
比較例２
実施例１において、塩化第二鉄（ＦｅＣｌ3・６Ｈ2Ｏ）の代わりに、塩化第一鉄（ＦｅＣｌ2）を用い、ｐＨを８に調整し、得られた沈殿物を７５℃で２４時間乾燥し、（ｃ）工程を行わなかった以外は、実施例１と同様に行った。得られたオキシ水酸化鉄のＢＥＴ比表面積は１３２．０ｍ2／ｇ、水酸基含有量は３．３ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨ、凝集体粒子としての平均粒子径は、１２３μｍであった。
Comparative Example 2
In Example 1, ferrous chloride (FeCl 2 ) was used in place of ferric chloride (FeCl 3 .6H 2 O), the pH was adjusted to 8, and the resulting precipitate was kept at 75 ° C. for 24 hours. The same procedure as in Example 1 was performed except that the drying and the step (c) were not performed. The obtained iron oxyhydroxide had a BET specific surface area of 132.0 m 2 / g, a hydroxyl group content of 3.3 mol-OH / kg-FeOOH, and an average particle size as aggregate particles of 123 μm.
比較例３〜５
実施例２〜１０において、乾燥条件を第１表に記載した条件としたこと以外は、実施例２〜１０と同様に行った。結果を第１表に示す。
Comparative Examples 3-5
In Examples 2-10, it carried out similarly to Examples 2-10 except having made the drying conditions into the conditions described in Table 1. The results are shown in Table 1.
（オキシ水酸化鉄の評価）
評価試験１
実施法１〜５で得られたオキシ水酸化鉄を、リン濃度５０ｍｇ／Ｌのリン酸溶液に１ｇ／Ｌの割合で投入し、リン酸イオンの吸着性能を評価した。結果を図１に示す。図１から、乾燥温度が５０℃から上昇するに従ってリン吸着量が徐々に減少するが、乾燥温度９０℃でリン吸着率５５％を示し、乾燥温度６０℃未満でリン吸着率７０％以上を示していることが分かる。
なお、リン吸着率（％）は、下式により算出した。
リン吸着率（％）＝（吸着実験後のリン濃度／吸着実験前のリン濃度）×１００
(Evaluation of iron oxyhydroxide)
Evaluation test 1
The iron oxyhydroxide obtained in Examples 1 to 5 was introduced into a phosphoric acid solution having a phosphorus concentration of 50 mg / L at a rate of 1 g / L, and the phosphate ion adsorption performance was evaluated. The results are shown in FIG. From FIG. 1, the phosphorus adsorption amount gradually decreases as the drying temperature increases from 50 ° C., but shows a phosphorus adsorption rate of 55% at a drying temperature of 90 ° C., and a phosphorus adsorption rate of 70% or more at a drying temperature of less than 60 ° C. I understand that
The phosphorus adsorption rate (%) was calculated by the following formula.
Phosphorus adsorption rate (%) = (phosphorus concentration after adsorption experiment / phosphorus concentration before adsorption experiment) × 100
評価試験２
フーリエ変換赤外分光光度計（日本電子社製：型式ＳＰＸ60）を用いて、実施例１で得られたオキシ水酸化鉄、及び市販試薬のオキシ水酸化鉄（α−ＦｅＯＯＨ、ナカライテスク社製）について、ＦｅＯＯＨの水素結合サイトとして、 Ｏ−Ｈの伸縮状態を測定した。結果を図２に示す。
図２から、市販試薬のα−ＦｅＯＯＨも、実施例１で得られたＦｅＯＯＨも、波数２４００ｃｍ-1〜３７００ｃｍ-1にピークが存在しているが、実施例１で得られたＦｅＯＯＨは、波数３４２０ｃｍ-1に大きなピークが存在しており、リン酸イオン等の陰イオン種の吸着能を示す弱い水素結合の水酸基を大量に含有していることが分る。
図３は、実施例１で得られたＦｅＯＯＨを用いて、評価試験１を行った場合のリン酸イオン吸着前と吸着後のＦＴＩＲスペクトルである。リン酸イオン吸着前の波数３４２０ｃｍ-1のピークの水酸基含有量は８．２７ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨであり、リン酸イオン吸着後の波数３４２０ｃｍ-1のピークの水酸基含有量は３．５４ｍｏｌ−ＯＨ／ｋｇ−ＦｅＯＯＨであった。このようにリン酸イオン吸着後のＦＴＩＲスペクトルは３４２０ｃｍ-1のピークが激減している。これはＦｅＯＯＨの水素結合サイトのＯＨ基の脱離と同時にリン酸イオンが吸着したことを示している。このことから、リン酸イオン等の陰イオン種の吸着除去には、水素結合サイトが寄与していることが分る。
図４は、実施例１において、（ｂ）工程における乾燥温度を５０℃〜４００℃に変化させた場合のＦＴＩＲスペクトルである。加熱温度が上昇するに従って３４２０ｃｍ-1のピークが減少し、１００℃を超えた温度で乾燥すると、水素結合サイトが大幅に減少し、リン酸イオン等の陰イオン種の吸着能が大幅に低下することが分かる。
Evaluation test 2
Using a Fourier transform infrared spectrophotometer (manufactured by JEOL Ltd .: model SPX60), the iron oxyhydroxide obtained in Example 1 and the commercially available iron oxyhydroxide (α-FeOOH, manufactured by Nacalai Tesque) As for the hydrogen bonding site of FeOOH, the stretched state of O—H was measured. The results are shown in FIG.
From FIG. 2, both the commercially available reagent α-FeOOH and the FeOOH obtained in Example 1 have a peak at
FIG. 3 shows FTIR spectra before and after phosphate ion adsorption when the evaluation test 1 is performed using FeOOH obtained in Example 1. The hydroxyl group content at the peak of wave number 3420 cm −1 before phosphate ion adsorption is 8.27 mol-OH / kg-FeOOH, and the hydroxyl group content at the peak of wave number 3420 cm −1 after phosphate ion adsorption is 3.54 mol − It was OH / kg-FeOOH. Thus, in the FTIR spectrum after phosphate ion adsorption, the peak at 3420 cm −1 is drastically reduced. This indicates that phosphate ions were adsorbed simultaneously with the elimination of the OH group at the hydrogen bonding site of FeOOH. From this, it can be seen that hydrogen bonding sites contribute to the adsorption removal of anionic species such as phosphate ions.
FIG. 4 is an FTIR spectrum when the drying temperature in the step (b) is changed from 50 ° C. to 400 ° C. in Example 1. As the heating temperature rises, the peak at 3420 cm -1 decreases, and when it is dried at a temperature exceeding 100 ° C., the hydrogen bonding sites are greatly reduced and the adsorption ability of anionic species such as phosphate ions is greatly reduced. I understand that.
評価試験３
実施例１で得られたオキシ水酸化鉄と市販試薬のオキシ水酸化鉄（α−ＦｅＯＯＨ、ナカライテスク社製）、及びリン酸イオン含有水（和光純薬工業株式会社製リン標準液）を用いて、リン吸着量とリン平衡濃度の関係（オキシ水酸化鉄量１ｇ／Ｌ、接触時間２４時間）を評価した。結果を図５に示す。
図５からリン酸イオン平衡濃度が上昇するにつれてリン酸イオン吸着量も増加し、実施例１で得られたオキシ水酸化鉄では、平衡濃度２００ｍｇ／Ｌでリン吸着量は４０ｍｇ／ｇあった。一方、市販試薬のオキシ水酸化鉄では、平衡濃度２００ｍｇ／Ｌでリン吸着量は６ｍｇ／ｇあった。この結果、実施例１で得られたオキシ水酸化鉄は、市販試薬のオキシ水酸化鉄の６．７倍の吸着能があることが分る。
Evaluation test 3
Using the iron oxyhydroxide obtained in Example 1, the commercially available reagent iron oxyhydroxide (α-FeOOH, manufactured by Nacalai Tesque), and phosphate ion-containing water (phosphorus standard solution manufactured by Wako Pure Chemical Industries, Ltd.) Then, the relationship between the phosphorus adsorption amount and the phosphorus equilibrium concentration (iron oxyhydroxide amount 1 g / L, contact time 24 hours) was evaluated. The results are shown in FIG.
As shown in FIG. 5, the phosphate ion adsorption amount increased as the phosphate ion equilibrium concentration increased. With the iron oxyhydroxide obtained in Example 1, the phosphorus adsorption amount was 40 mg / g at an equilibrium concentration of 200 mg / L. On the other hand, iron oxyhydroxide, a commercially available reagent, had an adsorption concentration of 6 mg / g at an equilibrium concentration of 200 mg / L. As a result, it can be seen that the iron oxyhydroxide obtained in Example 1 has an adsorption capacity 6.7 times that of the commercially available iron oxyhydroxide.
評価試験４
リン酸イオン含有廃水（滋賀県石部地区工場排水、リン濃度（リン元素換算）５２．１９ｍｇ／Ｌ）に、実施例１で得られたオキシ水酸化鉄を添加して、リン酸イオン除去能の評価を行った。オキシ水酸化鉄を２ｇ／Ｌ−排水の割合で添加して、２４時間攪拌した後のリン濃度は０ｍｇ／Ｌであり、リン酸イオンを完全に除去できた。
Evaluation test 4
Phosphate ion-containing wastewater (Shiga Prefecture Ishibe district factory wastewater, phosphorus concentration (phosphorus element conversion) 52.19 mg / L) was added with the iron oxyhydroxide obtained in Example 1 to remove phosphate ions. Evaluation was performed. After adding iron oxyhydroxide at a rate of 2 g / L-drainage and stirring for 24 hours, the phosphorus concentration was 0 mg / L, and phosphate ions could be completely removed.
Claims (6)
（ｂ）該沈殿物を１００℃以下の温度で乾燥することによってオキシ水酸化鉄を得る工程、及び
（ｃ）得られたオキシ水酸化鉄を水と接触させた後、１００℃以下の温度で乾燥する工程、を順次行うことを特徴とするオキシ水酸化鉄の製造方法。 (A) A step of generating a precipitate containing iron oxyhydroxide by adding a base to a trivalent iron ion-containing solution and adjusting the pH to 3.3 to 6,
(B) drying the precipitate at a temperature of 100 ° C. or less to obtain iron oxyhydroxide; and (c) contacting the obtained iron oxyhydroxide with water, and then at a temperature of 100 ° C. or less. A method for producing iron oxyhydroxide, comprising sequentially performing a drying step.
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| WO2017061116A1 (en) * | 2015-10-09 | 2017-04-13 | 日本曹達株式会社 | Iron oxyhydroxide nanodispersion liquid |
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| US11325847B2 (en) | 2017-06-16 | 2022-05-10 | Takahashi Metal Industries Co., Ltd. | Adsorption method |
| JP7024967B2 (en) * | 2018-02-26 | 2022-02-24 | 国立大学法人京都大学 | Manufacturing method of adsorbent |
| JP7236143B2 (en) | 2019-06-20 | 2023-03-09 | 株式会社杉田製線 | Water purification material containing iron as main component and method for producing the same |
| JP7154598B2 (en) | 2019-06-20 | 2022-10-18 | 株式会社杉田製線 | Water purification material and water purification method using the same |
| WO2021029534A1 (en) * | 2019-08-13 | 2021-02-18 | 주식회사 엘지화학 | Iron oxyhydroxynitrate having phosphoric acid anion-adsorbed surface, preparation method therefor, cathode comprising iron oxyhydroxynitrate having phosphoric acid anion-adsorbed surface for lithium secondary battery, and lithium secondary battery comprising same |
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