JP5467340B2 - Compound using coal ash as raw material and method for producing the same - Google Patents
Compound using coal ash as raw material and method for producing the same Download PDFInfo
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- JP5467340B2 JP5467340B2 JP2009235552A JP2009235552A JP5467340B2 JP 5467340 B2 JP5467340 B2 JP 5467340B2 JP 2009235552 A JP2009235552 A JP 2009235552A JP 2009235552 A JP2009235552 A JP 2009235552A JP 5467340 B2 JP5467340 B2 JP 5467340B2
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- coal ash
- iron
- hfafe
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- hfa
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- 239000010883 coal ash Substances 0.000 title claims description 307
- 239000002994 raw material Substances 0.000 title claims description 39
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 150000001875 compounds Chemical class 0.000 title claims description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 56
- 238000001179 sorption measurement Methods 0.000 claims description 45
- -1 iron ions Chemical class 0.000 claims description 42
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 37
- 229910052742 iron Inorganic materials 0.000 claims description 33
- 239000000243 solution Substances 0.000 claims description 30
- 125000005372 silanol group Chemical group 0.000 claims description 26
- 239000007864 aqueous solution Substances 0.000 claims description 18
- 150000001450 anions Chemical class 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000013067 intermediate product Substances 0.000 claims description 8
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 claims description 7
- 239000003245 coal Substances 0.000 claims description 4
- 239000012670 alkaline solution Substances 0.000 claims description 2
- 239000002956 ash Substances 0.000 claims description 2
- 239000012488 sample solution Substances 0.000 description 34
- 238000005341 cation exchange Methods 0.000 description 31
- 229910052785 arsenic Inorganic materials 0.000 description 30
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 30
- 238000012360 testing method Methods 0.000 description 29
- 238000005349 anion exchange Methods 0.000 description 24
- 238000010828 elution Methods 0.000 description 20
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 18
- 229910052804 chromium Inorganic materials 0.000 description 18
- 239000011651 chromium Substances 0.000 description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 17
- 239000000126 substance Substances 0.000 description 17
- 239000000523 sample Substances 0.000 description 15
- 239000003153 chemical reaction reagent Substances 0.000 description 13
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 11
- 229910052711 selenium Inorganic materials 0.000 description 11
- 239000011669 selenium Substances 0.000 description 11
- 239000006228 supernatant Substances 0.000 description 11
- 238000002076 thermal analysis method Methods 0.000 description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 10
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 10
- 229910052731 fluorine Inorganic materials 0.000 description 10
- 239000011737 fluorine Substances 0.000 description 10
- 150000002500 ions Chemical class 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 229940085991 phosphate ion Drugs 0.000 description 10
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 9
- 229910052796 boron Inorganic materials 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 8
- 230000007613 environmental effect Effects 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
- 229920006395 saturated elastomer Polymers 0.000 description 7
- 229910021536 Zeolite Inorganic materials 0.000 description 6
- 229910001583 allophane Inorganic materials 0.000 description 6
- 150000001768 cations Chemical class 0.000 description 6
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 6
- 238000005342 ion exchange Methods 0.000 description 6
- 239000010457 zeolite Substances 0.000 description 6
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000011780 sodium chloride Substances 0.000 description 5
- 239000013585 weight reducing agent Substances 0.000 description 5
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 229910019142 PO4 Inorganic materials 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 239000011609 ammonium molybdate Substances 0.000 description 4
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 4
- 235000018660 ammonium molybdate Nutrition 0.000 description 4
- 229940010552 ammonium molybdate Drugs 0.000 description 4
- 238000005119 centrifugation Methods 0.000 description 4
- 125000000524 functional group Chemical group 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000010452 phosphate Substances 0.000 description 4
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- AVXURJPOCDRRFD-UHFFFAOYSA-N Hydroxylamine Chemical group ON AVXURJPOCDRRFD-UHFFFAOYSA-N 0.000 description 3
- 239000003929 acidic solution Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000004737 colorimetric analysis Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000013101 initial test Methods 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000011068 loading method Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 239000012086 standard solution Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229910018512 Al—OH Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000000274 adsorptive effect Effects 0.000 description 2
- 235000010323 ascorbic acid Nutrition 0.000 description 2
- 229960005070 ascorbic acid Drugs 0.000 description 2
- 239000011668 ascorbic acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000383 hazardous chemical Substances 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000004949 mass spectrometry Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229910000160 potassium phosphate Inorganic materials 0.000 description 2
- 235000011009 potassium phosphates Nutrition 0.000 description 2
- IIQJBVZYLIIMND-UHFFFAOYSA-J potassium;antimony(3+);2,3-dihydroxybutanedioate Chemical compound [K+].[Sb+3].[O-]C(=O)C(O)C(O)C([O-])=O.[O-]C(=O)C(O)C(O)C([O-])=O IIQJBVZYLIIMND-UHFFFAOYSA-J 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 239000003440 toxic substance Substances 0.000 description 2
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- KQROHCSYOGBQGJ-UHFFFAOYSA-N 5-Hydroxytryptophol Chemical compound C1=C(O)C=C2C(CCO)=CNC2=C1 KQROHCSYOGBQGJ-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- KSPIHGBHKVISFI-UHFFFAOYSA-N Diphenylcarbazide Chemical compound C=1C=CC=CC=1NNC(=O)NNC1=CC=CC=C1 KSPIHGBHKVISFI-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910002803 Si-O-Fe Inorganic materials 0.000 description 1
- 229910008051 Si-OH Inorganic materials 0.000 description 1
- 229910002802 Si–O–Fe Inorganic materials 0.000 description 1
- 229910002808 Si–O–Si Inorganic materials 0.000 description 1
- 229910006358 Si—OH Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000004455 differential thermal analysis Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000008262 pumice Substances 0.000 description 1
- 206010037844 rash Diseases 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 231100000167 toxic agent Toxicity 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Landscapes
- Silicates, Zeolites, And Molecular Sieves (AREA)
Description
本発明は、吸着能を有する石炭灰を原料とする化合物に係り、陰イオンの吸着能をも有する石炭灰を原料とする化合物に関する。 The present invention relates to a compound using coal ash having an adsorption ability as a raw material, and relates to a compound using coal ash having an anion adsorption ability as a raw material .
水質浄化や、有害物質の固定もしくは拡散防止を目的として用いられる環境浄化資材の代表的なものとして、ゼオライトやアロフェンが挙げられる。ゼオライトは、もとは天然に産出する鉱物であり、結晶中に微細孔を有するとともに微細孔内にナトリウムなどのカチオンを含むことから、吸着能、イオン交換能、及び触媒としての機能を有する。また、アロフェンは、火山灰および軽石などの降下火山噴出物を母材とする土壌に現れる非結晶性もしくは低結晶質粘土成分からなるものであり、高い比表面積を有することから、吸着能及びイオン交換能を有する。 Zeolite and allophane are typical examples of environmental purification materials used for the purpose of water purification and the fixing or prevention of diffusion of harmful substances. Zeolite is a naturally occurring mineral that has fine pores in the crystal and contains cations such as sodium in the fine pores, and thus has an adsorption capacity, ion exchange capacity, and a function as a catalyst. Allophane is composed of non-crystalline or low-crystalline clay components that appear in soils based on volcanic eruptions such as volcanic ash and pumice, and has a high specific surface area, so it has adsorption capacity and ion exchange. Have the ability.
これらのゼオライト及びアロフェンは、主な構成元素として珪素とアルミニウムとを含むことから、これらの元素を多く含有する石炭灰からゼオライト及びアロフェンを人工的に合成する技術が提案されている（例えば、特許文献１又は２）。 Since these zeolite and allophane contain silicon and aluminum as main constituent elements, a technique for artificially synthesizing zeolite and allophane from coal ash containing a large amount of these elements has been proposed (for example, patents). Literature 1 or 2).
特許文献１には、石炭灰とアルカリ性物質を混合し、加熱溶融させた後、加熱処理をすることによりゼオライトを製造する方法が開示されている。また、特許文献２には、本発明者により、珪酸およびアルミニウムを含む無機成分に、アルカリ水溶液を加えて、加熱し、溶解し、次いでアルミニウムとキレート化合物を作らない酸性溶液を加えて、微酸性にした後、加熱することによりアロフェンを製造する方法が開示されている。 Patent Document 1 discloses a method for producing zeolite by mixing coal ash and an alkaline substance, heating and melting the mixture, and then performing heat treatment. In addition, in Patent Document 2, the present inventors added an alkaline aqueous solution to an inorganic component containing silicic acid and aluminum, heated and dissolved, and then added an acidic solution that does not form a chelate compound with aluminum, and added a slightly acidic solution. After that, a method for producing allophane by heating is disclosed.
しかしながら、特許文献１に記載のゼオライトの製造方法では、アルカリ性物質を混合するとともに加熱溶融温度を１０００℃以上に設定することを要し、また、特許文献２に記載のアロフェンの製造方法では、アルカリ水溶液と酸性溶液の両者を大量に使用するため、エネルギーコストや材料コストが嵩んでしまう。 However, in the method for producing zeolite described in Patent Document 1, it is necessary to mix an alkaline substance and to set the heating and melting temperature to 1000 ° C. or more. In the method for producing allophane described in Patent Document 2, Since a large amount of both an aqueous solution and an acidic solution are used, energy costs and material costs increase.
また、これらの製造方法を実施するためには、耐熱・耐薬品用の機器を導入や機器を維持管理するための設備コストも発生してしまう。 Moreover, in order to implement these manufacturing methods, the installation cost for introducing and maintaining equipment for heat and chemical resistance also occurs.
本発明は、上記の点に鑑みてなされてものであり、簡便かつ低コストに製造できるとともに、陰イオンの吸着能をも有する石炭灰を原料とする化合物及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above points, and an object thereof is to provide a compound using coal ash as a raw material, which can be produced easily and at low cost, and also has anion adsorption capacity, and a method for producing the same. And
上記の目的を達成するため、本発明の石炭灰組成物は、陰イオンの吸着能を有する、石炭灰を原料とする化合物であって、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を、亜臨界水処理によりシラノール基が付加された石炭灰の表面に有することを特徴とする。この石炭灰を原料とする化合物は、石炭灰を亜臨界水処理し、前記石炭灰の表面にシラノール基を有する中間生成物を製造する第１工程と、鉄イオンを含有する金属溶液を前記中間生成物に添加し、前記石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成する第２工程とを経て製造される。 In order to achieve the above object, the coal ash composition of the present invention is a compound using coal ash as a raw material, which has anion adsorption ability, and has a Si—O— Fe—OH linkage structure having a subcriticality. It is characterized by having on the surface of coal ash to which silanol groups have been added by water treatment . The compound using coal ash as a raw material is obtained by subjecting coal ash to subcritical water treatment to produce an intermediate product having a silanol group on the surface of the coal ash, and a metal solution containing iron ions in the intermediate It is added to the product and manufactured through a second step of forming a Si—O— Fe—OH connection structure on the surface of the coal ash.
このような石炭灰を原料とする化合物によれば、石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造を有しているので、Ｆｅ−ＯＨ基によって陰イオンを吸着させることができる。また、この石炭灰を原料とする化合物は、石炭灰の亜臨界水処理で得られた中間生成物に対して金属溶液を添加することで製造できる。このため、エネルギー、材料及び設備のコスト低減に寄与する。 According to such a compound using coal ash as a raw material, an anion can be adsorbed by the Fe- OH group because the surface of the coal ash has a Si-O- Fe-OH connection structure. Moreover, the compound which uses this coal ash as a raw material can be manufactured by adding a metal solution with respect to the intermediate product obtained by the subcritical water process of coal ash. For this reason, it contributes to the cost reduction of energy, material, and an installation.
前述の石炭灰を原料とする化合物において、石炭灰の表面に、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成することが環境上好ましい。そして、Ｆｅを効率よく担持させるためには、ヒドロキシ鉄イオンを含有する金属溶液を前記中間生成物に添加することが好ましい。 In the above-described compound using coal ash as a raw material, it is environmentally preferable to form a Si—O—Fe—OH connection structure on the surface of the coal ash. And in order to carry | support Fe efficiently, it is preferable to add the metal solution containing a hydroxy iron ion to the said intermediate product .
また、石炭灰の亜臨界水処理は、石炭灰と、水又はアルカリ性溶液との混合体を、１５０℃以上の温度で６０分以上加熱することが好ましい。 In the subcritical water treatment of coal ash, it is preferable to heat a mixture of coal ash and water or an alkaline solution for 60 minutes or more at a temperature of 150 ° C. or higher.
本発明によれば、簡便かつ低コストに製造できるとともに、陰イオンの吸着能をも有する石炭灰を原料とする化合物及びその製造方法を提供できる。
ADVANTAGE OF THE INVENTION According to this invention, while being able to manufacture simply and at low cost, the compound which uses the coal ash which has the adsorption ability of an anion as a raw material, and its manufacturing method can be provided.
＜製造工程等について＞
以下、本発明の好ましい一実施形態について図面に基づき詳細に説明する。ここでは、石炭火力発電所において排出された石炭灰から鉄型水和石炭灰（石炭灰組成物）を製造する場合を例に挙げて説明する。図１は、本実施形態に係る鉄型水和石炭灰の製造設備及び製造工程の説明図である。
<About manufacturing processes>
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. Here, a case where iron-type hydrated coal ash (coal ash composition) is produced from coal ash discharged at a coal-fired power plant will be described as an example. FIG. 1 is an explanatory diagram of a production facility and a production process of iron-type hydrated coal ash according to the present embodiment.
鉄型水和石炭灰の製造設備は、オートクレーブ１０（高温圧力釜）と、反応容器２０と、遠心分離器３０と、凍結乾燥機４０とを有する。 The production facility for iron-type hydrated coal ash includes an autoclave 10 (high temperature pressure kettle), a reaction vessel 20, a centrifuge 30, and a freeze dryer 40.
オートクレーブ１０は、石炭灰ＦＡと水Ｗとの混合体を１５０℃以上の温度で６０分以上加熱することで石炭灰ＦＡを亜臨界水処理する装置である。石炭灰ＦＡを亜臨界水処理することで、石炭灰ＦＡの表面にシラノール基を有する水和石炭灰ＨＦＡ（石炭灰組成物）が生成される。 The autoclave 10 is a device for subjecting the coal ash FA to subcritical water treatment by heating a mixture of the coal ash FA and water W at a temperature of 150 ° C. or more for 60 minutes or more. By subjecting the coal ash FA to subcritical water treatment, a hydrated coal ash HFA (coal ash composition) having a silanol group on the surface of the coal ash FA is generated.
なお、オートクレーブ１０における設定温度と飽和蒸気圧の関係は、次の通りである。設定温度が１５０℃のときの飽和蒸気圧は０．４ＭＰａであり、設定温度２００℃のときの飽和蒸気圧は１．５ＭＰａである。また、設定温度２５０℃のときの飽和蒸気圧は３．９ＭＰａであり、設定温度３００℃のときの飽和蒸気圧は８．５ＭＰａである。 The relationship between the set temperature and the saturated vapor pressure in the autoclave 10 is as follows. The saturated vapor pressure when the set temperature is 150 ° C. is 0.4 MPa, and the saturated vapor pressure when the set temperature is 200 ° C. is 1.5 MPa. Further, the saturated vapor pressure when the set temperature is 250 ° C. is 3.9 MPa, and the saturated vapor pressure when the set temperature is 300 ° C. is 8.5 MPa.
石炭灰ＦＡとしては、石炭火力発電所が有する微粉炭ボイラー５０の燃焼排ガス中から回収されたフライアッシュを用いる。オートクレーブ１０で加熱を行うための熱源としては、例えば、発電所の蒸気タービン６０の動力として使用された蒸気を用いることが好ましい。本実施形態において、石炭灰ＦＡと水Ｗとの混合比率は、石炭灰ＦＡを２０重量部に対し水Ｗを８０重量部としている。そして、石炭灰ＦＡと水Ｗとの混合体を３００℃の温度で３００分加熱することで、石炭灰ＦＡを亜臨界水処理している。なお、水Ｗに関し、水酸化ナトリウム等を混合してｐＨ１２〜１３程度のアルカリ性としてもよい。 As coal ash FA, the fly ash collect | recovered from the combustion exhaust gas of the pulverized coal boiler 50 which a coal thermal power plant has is used. As a heat source for heating in the autoclave 10, it is preferable to use, for example, steam used as power for the steam turbine 60 of the power plant. In this embodiment, the mixing ratio of coal ash FA and water W is 80 parts by weight of water W with respect to 20 parts by weight of coal ash FA. And the coal ash FA is subcritical water-treated by heating the mixture of coal ash FA and the water W for 300 minutes at the temperature of 300 degreeC. In addition, regarding water W, it is good also as alkalinity about pH 12-13 by mixing sodium hydroxide etc.
反応容器２０は、亜臨界水処理後の水和石炭灰ＨＦＡに鉄イオンを含有する金属溶液を添加することで、水和石炭灰ＨＦＡを鉄型変換する部分である。水和石炭灰ＨＦＡの鉄型変換により鉄型水和石炭灰ＨＦＡＦｅが得られる。 The reaction vessel 20 is a part that converts the hydrated coal ash HFA into an iron type by adding a metal solution containing iron ions to the hydrated coal ash HFA after the subcritical water treatment. Iron-type hydrated coal ash HFAFe is obtained by iron-type conversion of hydrated coal ash HFA.
本実施形態では、鉄型変換に際してヒドロキシ鉄イオンを含有する金属溶液を用いている。鉄型変換の手順は次の通りである。まず、濃度が０．０５〜０．１Ｍの塩化鉄水溶液を調整する。この塩化鉄水溶液を、水酸化ナトリウム水溶液を加えてｐＨ３〜４に調整しながら、水和石炭灰ＨＦＡに添加する。その際、ヒドロキシ鉄イオン担持量が、水和石炭灰１ｇあたり、Ｆｅとして、０．５ｍｍｏｌから２．５ｍｍｏｌになるように添加する。そして、１分間あたり１００回転くらいの速さで攪拌部材（ガラス棒や回転子）を回転させて、塩化鉄水溶液を添加した後の水和石炭灰ＨＦＡを攪拌する。なお、このときの温度は室温（２０〜２５℃）である。塩化鉄水溶液の添加及び攪拌によって、図２に示すように、石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造が形成される。すなわち、鉄型水和石炭灰ＨＦＡＦｅが生成される。 In the present embodiment, a metal solution containing hydroxy iron ions is used for the iron type conversion. The procedure for iron type conversion is as follows. First, an iron chloride aqueous solution having a concentration of 0.05 to 0.1M is prepared. This iron chloride aqueous solution is added to the hydrated coal ash HFA while adjusting the pH to 3 to 4 by adding an aqueous sodium hydroxide solution. In that case, it adds so that the amount of hydroxy iron ion carrying | support may be 0.5 mmol to 2.5 mmol as Fe per g of hydrated coal ash. Then, the stirring member (glass rod or rotor) is rotated at a speed of about 100 revolutions per minute to stir the hydrated coal ash HFA after adding the iron chloride aqueous solution. In addition, the temperature at this time is room temperature (20-25 degreeC). By adding and stirring the aqueous iron chloride solution, a Si—O—Fe—OH connection structure is formed on the surface of the coal ash, as shown in FIG. That is, iron-type hydrated coal ash HFAFe is produced.
遠心分離器３０は、水洗後の鉄型水和石炭灰ＨＦＡＦｅを含有する混合体を、鉄型水和石炭灰ＨＦＡＦｅと液体部分とに遠心分離する。凍結乾燥機４０は、遠心分離後の鉄型水和石炭灰ＨＦＡＦｅを凍結させ乾燥させる。凍結乾燥機４０で凍結乾燥させることで、粉末状の鉄型水和石炭灰ＨＦＡＦｅが得られる。なお、遠心分離器３０による分離に代えて水洗と沈降とを繰り返し行ってもよい。また、凍結乾燥機４０による乾燥に代えて乾燥炉による乾燥を行ってもよい。 The centrifuge 30 centrifuges the mixture containing the iron-type hydrated coal ash HFAFe after washing with water into the iron-type hydrated coal ash HFAFe and the liquid portion. The freeze dryer 40 freezes and dries the iron-type hydrated coal ash HFAFe after centrifugation. By freeze-drying with the freeze dryer 40, powdered iron-type hydrated coal ash HFAFe is obtained. Note that water washing and sedimentation may be repeatedly performed instead of separation by the centrifuge 30. Further, instead of drying by the freeze dryer 40, drying by a drying furnace may be performed.
＜水和石炭灰ＨＦＡについて＞
中間生成物である水和石炭灰ＨＦＡ、及び水和石炭灰ＨＦＡの原料物質となる石炭灰ＦＡ（以下、原料石炭灰ＦＡともいう。）について、熱分析並びに走査型電子顕微鏡による観察を行った。図３に原料石炭灰ＦＡの熱分析結果を、図４に水和石炭灰ＨＦＡの熱分析結果をそれぞれ示す。図５に原料石炭灰ＦＡの顕微鏡写真を、図６に水和石炭灰ＨＦＡの顕微鏡写真をそれぞれ示す。以下、分析結果及び観察結果について説明する。
<About hydrated coal ash HFA>
About the hydrated coal ash HFA which is an intermediate product, and the coal ash FA which is a raw material of the hydrated coal ash HFA (hereinafter also referred to as raw material coal ash FA), thermal analysis and observation by a scanning electron microscope were performed. . FIG. 3 shows the thermal analysis results of the raw coal ash FA, and FIG. 4 shows the thermal analysis results of the hydrated coal ash HFA. FIG. 5 shows a micrograph of raw coal ash FA, and FIG. 6 shows a micrograph of hydrated coal ash HFA. Hereinafter, analysis results and observation results will be described.
熱分析によるシラノール基重量率の測定は、水和石炭灰ＨＦＡが有するシラノール基が５００℃程度まで加熱されるまでに完全燃焼する特性を利用したものであり、水和石炭灰ＨＦＡの吸着能の要因と考えられるシラノール基の重量を把握できる。ここでは、熱重量・示差熱分析法（ＴＧ−ＤＴＡ）を採用し、所定量の試料を常温から１０００℃まで加熱した。 The measurement of the weight ratio of silanol groups by thermal analysis is based on the characteristic that the silanol groups of the hydrated coal ash HFA are completely combusted before being heated to about 500 ° C. The weight of the silanol group considered to be a factor can be grasped. Here, thermogravimetric / differential thermal analysis (TG-DTA) was employed, and a predetermined amount of the sample was heated from room temperature to 1000 ° C.
図３及び図４において、横軸は温度[℃]、左側縦軸は重量変化［％］、右側縦軸は温度差［μＶ］である。これらの図を比較すると、室温から６００℃の範囲において、亜臨界水処理を施した水和石炭灰ＨＦＡの重量（図４の一点鎖線を参照）は、原料石炭灰ＦＡの重量（図３の一点鎖線を参照）に比べて大きく減少している。この重量減少から、亜臨界水処理によって石炭灰表面のシロキサン結合（Ｓｉ−Ｏ−Ｓｉ）が切断され、石炭灰表面に多数のシラノール基（Ｓｉ−ＯＨ）が出現したことが判る。すなわち、多数のシラノール基が出現して、構造中に含まれるＯＨ基の量や吸着される水分子の量が原料石炭灰ＦＡよりも増えたと考えられる。そして、シラノール基等の官能基が新たに生じることで、原料石炭灰ＦＡには殆どみられない好都合な特性が発現される。例えば、陽イオンの吸着能が発現される。 3 and 4, the horizontal axis represents temperature [° C.], the left vertical axis represents weight change [%], and the right vertical axis represents temperature difference [μV]. Comparing these figures, the weight of the hydrated coal ash HFA subjected to subcritical water treatment (see the one-dot chain line in FIG. 4) in the range from room temperature to 600 ° C. is the weight of the raw coal ash FA (see FIG. 3). Compared to the alternate long and short dash line). From this weight reduction, it can be seen that the siloxane bond (Si—O—Si) on the surface of the coal ash was cut by the subcritical water treatment, and a large number of silanol groups (Si—OH) appeared on the surface of the coal ash. That is, it is considered that a large number of silanol groups appeared, and the amount of OH groups contained in the structure and the amount of adsorbed water molecules increased compared to the raw material coal ash FA. Then, by newly generating a functional group such as a silanol group, advantageous characteristics hardly seen in the raw material coal ash FA are expressed. For example, the ability to adsorb cations is expressed.
なお、水和石炭灰ＨＦＡは、６００℃から８００℃の温度範囲でも重量の減少がみられる。実線で示すように、この温度範囲に発熱ピークもみられることから、この重量減少は、未燃焼炭素など水和石炭灰ＨＦＡに少量含まれる炭素に起因するものと解される。 The hydrated coal ash HFA shows a decrease in weight even in the temperature range from 600 ° C to 800 ° C. As indicated by the solid line, since an exothermic peak is also observed in this temperature range, it is understood that this weight reduction is caused by carbon contained in a small amount in hydrated coal ash HFA such as unburned carbon.
次に、顕微鏡による観察結果について説明する。図５に示すように、原料石炭灰ＦＡは、球形を呈しており、その表面は多少の突部がみられるものの平滑といえる。なお、表面の突部は、極めて小さい微小石炭灰の付着によって形成されたと考えられる。一方、図６に示すように、水和石炭灰ＨＦＡは、原料石炭灰ＦＡに比べて大きな凹凸が見られ、球の形も歪んでいる。この違いは、石炭灰表面に多数のシラノール基が出現したことに起因していると考えられる。 Next, observation results using a microscope will be described. As shown in FIG. 5, the raw material coal ash FA has a spherical shape, and it can be said that the surface is smooth although some protrusions are seen. In addition, it is thought that the protrusion of the surface was formed by adhesion of very small fine coal ash. On the other hand, as shown in FIG. 6, the hydrated coal ash HFA has larger irregularities than the raw material coal ash FA, and the sphere shape is also distorted. This difference is thought to be due to the appearance of many silanol groups on the coal ash surface.
＜鉄型水和石炭灰ＨＦＡＦｅについて＞
前述したように、鉄型水和石炭灰ＨＦＡＦｅは水和石炭灰ＨＦＡを鉄型変換することで作製される。本実施形態では、ヒドロキシ鉄イオンを含有する溶液を水和石炭灰ＨＦＡに添加することで、鉄型水和石炭灰ＨＦＡＦｅを作製している。
<About iron-type hydrated coal ash HFAFe>
As described above, iron-type hydrated coal ash HFAFe is produced by iron-type conversion of hydrated coal ash HFA. In this embodiment, the iron-type hydrated coal ash HFAFe is produced by adding a solution containing hydroxy iron ions to the hydrated coal ash HFA.
ここで、ヒドロキシ鉄イオンについて説明する。一般に呼ばれる鉄イオンとは、図７の最上段に示すヘキサハイドロ鉄イオンをいう。ヘキサハイドロ鉄イオンを含有する溶液に水酸化物イオン（ＯＨ−）を加えていくと、ヘキサハイドロ鉄イオンは、図７の上から２段目に示すように、加水分解によってプロトンを失う。プロトンを失った鉄イオンは、図７の上から３段目に示すように、２分子間でＯＨを橋架けとして縮合を起こし、鉄イオンを２つ含んだ錯イオンを生成する。このような縮合反応をオール化といい、核となるイオン（鉄イオン）を２つ含んだ錯イオンのことを複核錯イオンという。この複核錯イオンもまた加水分解とオール化を繰り返し、ＯＨを橋架けとして連なる。これにより、図８に示すように、高分子量の多核錯イオンが形成される。 Here, the hydroxy iron ion will be described. The generally called iron ion refers to the hexahydro iron ion shown at the top of FIG. When hydroxide ions (OH − ) are added to a solution containing hexahydroiron ions, the hexahydroiron ions lose protons by hydrolysis as shown in the second row from the top of FIG. As shown in the third row from the top in FIG. 7, the iron ions that have lost their protons undergo condensation by bridging OH between two molecules to generate complex ions containing two iron ions. Such a condensation reaction is called olation, and a complex ion containing two core ions (iron ions) is called a binuclear complex ion. This binuclear complex ion also repeats hydrolysis and olation, and continues with OH as a bridge. Thereby, as shown in FIG. 8, a high molecular weight polynuclear complex ion is formed.
本実施形態では、塩化鉄水溶液に水酸化ナトリウム水溶液を加えてヒドロキシ鉄イオンを生成し、ヒドロキシ鉄イオンを含んだ溶液（金属溶液）を水和石炭灰ＨＦＡに添加している。本実施形態では、ヒドロキシ鉄イオン担持量が水和石炭灰１ｇあたり０．５ｍｍｏｌから２．５ｍｍｏｌになるように、金属溶液を水和石炭灰ＨＦＡに添加している。 In this embodiment, a sodium hydroxide aqueous solution is added to an iron chloride aqueous solution to generate hydroxy iron ions, and a solution (metal solution) containing hydroxy iron ions is added to the hydrated coal ash HFA. In the present embodiment, the metal solution is added to the hydrated coal ash HFA so that the supported amount of hydroxyiron ions is 0.5 mmol to 2.5 mmol per 1 g of hydrated coal ash.
生成された鉄型水和石炭灰ＨＦＡＦｅについて、熱分析並びに走査型電子顕微鏡による観察を行った。図９に鉄型水和石炭灰ＨＦＡＦｅの熱分析結果を、図１０に鉄型水和石炭灰ＨＦＡＦｅの顕微鏡写真をそれぞれ示す。なお、熱分析や顕微鏡観察に用いた鉄型水和石炭灰ＨＦＡＦｅは、ヒドロキシ鉄イオンの担持量が水和石炭灰１ｇあたり２．５ｍｍｏｌのものを用いた。なお、熱分析の条件は、原料石炭灰ＦＡや水和石炭灰ＨＦＡの分析条件と同じである。 The produced iron-type hydrated coal ash HFAFe was subjected to thermal analysis and observation with a scanning electron microscope. FIG. 9 shows a thermal analysis result of the iron-type hydrated coal ash HFAFe, and FIG. 10 shows a micrograph of the iron-type hydrated coal ash HFAFe. In addition, the iron-type hydrated coal ash HFAFe used for thermal analysis and microscopic observation used that whose amount of supported hydroxyiron ions is 2.5 mmol per 1 g of hydrated coal ash. In addition, the conditions of thermal analysis are the same as the analysis conditions of raw material coal ash FA and hydrated coal ash HFA.
図９に示すように、室温から６００℃までの加熱による鉄型水和石炭灰ＨＦＡＦｅの重量減少（図９の一点鎖線を参照）は、水和石炭灰ＨＦＡの重量減少（図４の一点鎖線を参照）よりも大きいことが確認された。このことは、構造中に多数のＦｅ−ＯＨ基が形成されたことを意味する。なお、１００℃付近に吸熱ピークを伴う重量減少が確認されたが、この重量減少は、鉄型水和石炭灰ＨＦＡＦｅが多孔質であることから、吸着した水分子の離脱（蒸発）によるものと推測される。図１０に示すように、鉄型水和石炭灰の表面には、ヒドロキシ鉄イオンと見られる物質が張り付いており、水和石炭灰ＨＦＡの表面（図６を参照）よりも多くの空隙が存在することが判る。 As shown in FIG. 9, the weight reduction of the iron-type hydrated coal ash HFAFe by heating from room temperature to 600 ° C. (see the alternate long and short dash line in FIG. 9) It was confirmed that it was larger than This means that many Fe—OH groups were formed in the structure. In addition, although the weight reduction accompanying an endothermic peak was confirmed at around 100 ° C., this weight reduction is due to the separation (evaporation) of adsorbed water molecules because the iron-type hydrated coal ash HFAFe is porous. Guessed. As shown in FIG. 10, the surface of the iron-type hydrated coal ash is stuck with a substance that appears to be hydroxy iron ions, and there are more voids than the surface of the hydrated coal ash HFA (see FIG. 6). It can be seen that it exists.
＜鉄型水和石炭灰ＨＦＡＦｅ等の特性について＞
次に、鉄型水和石炭灰ＨＦＡＦｅ、及び、水和石炭灰ＨＦＡの特性について説明する。前述したように、鉄型水和石炭灰ＨＦＡＦｅは、石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造が形成されている。この連結構造におけるＯＨ基がイオン交換されるため、陰イオンの吸着能を有する。一方、水和石炭灰ＨＦＡは、石炭灰の表面にシラノール基が形成されている。そして、シラノール基が有するＨがイオン交換されるため、陽イオンの吸着能を有する。
<Characteristics of iron-type hydrated coal ash HFAFe>
Next, the characteristics of iron-type hydrated coal ash HFAFe and hydrated coal ash HFA will be described. As described above, the iron-type hydrated coal ash HFAFe has a Si—O—Fe—OH connection structure formed on the surface of the coal ash. Since the OH group in this connection structure is ion-exchanged, it has anion adsorption ability. On the other hand, the hydrated coal ash HFA has silanol groups formed on the surface of the coal ash. And since H which a silanol group has is ion-exchanged, it has the adsorption capacity of a cation.
このような特性を確認するため、微量有害物質の溶出試験、陽イオン交換容量（ＣＥＣ）の測定、陰イオン交換容量（ＡＥＣ）の測定、全クロムの吸着試験、砒素の吸着試験、及び、リン酸イオンの吸着試験を行った。 In order to confirm such characteristics, a toxic substance elution test, cation exchange capacity (CEC) measurement, anion exchange capacity (AEC) measurement, total chromium adsorption test, arsenic adsorption test, and phosphorus An acid ion adsorption test was conducted.
なお、微量有害物質の溶出試験は、石炭灰ＦＡ、水和石炭灰ＨＦＡ、鉄担持量が０．５ｍｍｏｌ／ｇの鉄型水和石炭灰ＨＦＡＦｅ（１）、鉄担持量が２．５ｍｍｏｌ／ｇの鉄型水和石炭灰ＨＦＡＦｅ（２）からなる４種類の試料について試験を行った。陽イオン交換容量及び陰イオン交換容量の測定は、上記の４種類に加え、鉄担持処理石炭灰（１）と、鉄担持処理石炭灰（２）とを加えた合計６種類の試料について試験を行った。 In addition, the elution test of a trace amount harmful substance is coal ash FA, hydrated coal ash HFA, iron-type hydrated coal ash HFAFe (1) having an iron loading of 0.5 mmol / g, and iron loading of 2.5 mmol / g. Four types of samples made of iron-type hydrated coal ash HFAFe (2) were tested. The cation exchange capacity and anion exchange capacity were measured for a total of 6 types of samples including iron-supported coal ash (1) and iron-supported coal ash (2) in addition to the above four types. went.
ここで、鉄担持処理石炭灰（１）とは、鉄担持量が０．５ｍｍｏｌ／ｇとなるように、原料石炭灰ＦＡにヒドロキシ鉄イオンを添加して得られたものである。また、鉄担持処理石炭灰（２）とは、鉄担持量が２．５ｍｍｏｌ／ｇとなるように、ヒドロキシ鉄イオンを添加した得られたものである。鉄型水和石炭灰ＨＦＡＦｅと比較すると、ヒドロキシ鉄イオンを添加する対象が相違している。すなわち、鉄型水和石炭灰ＨＦＡＦｅは、水和石炭灰ＨＦＡにヒドロキシ鉄イオンを添加しているのに対し、鉄担持処理石炭灰は、原料石炭灰ＦＡにヒドロキシ鉄イオンを添加している。 Here, the iron-supported coal ash (1) is obtained by adding hydroxy iron ions to the raw material coal ash FA so that the amount of iron supported is 0.5 mmol / g. Further, the iron-supported coal ash (2) is obtained by adding hydroxy iron ions so that the iron-supporting amount is 2.5 mmol / g. Compared with iron-type hydrated coal ash HFAFe, the target to which hydroxy iron ions are added is different. That is, the iron-type hydrated coal ash HFAFe adds hydroxy iron ions to the hydrated coal ash HFA, while the iron-supported coal ash adds hydroxy iron ions to the raw material coal ash FA.
また、全クロムの吸着試験は鉄型水和石炭灰ＨＦＡＦｅ（２）について、砒素の吸着試験は鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）について、リン酸イオンの吸着試験は鉄担持処理石炭灰ＨＦＡＦｅ（１）、（２）及び鉄型水和石炭灰（１）、（２）について、それぞれ試験を行った。 The total chromium adsorption test is for iron-type hydrated coal ash HFAFe (2), the arsenic adsorption test is for iron-type hydrated coal ash HFAFe (1), (2), and the phosphate ion adsorption test is for iron loading. The treated coal ash HFAFe (1) and (2) and the iron-type hydrated coal ash (1) and (2) were tested.
＜微量有害物質の溶出について＞
微量有害物質の溶出試験では、鉄型水和石炭灰ＨＦＡＦｅや水和石炭灰ＨＦＡそのものからの微量有害物質の溶出量を測定する。原料石炭灰ＦＡには、六価クロムや砒素等の微量有害物質が含まれており、この微量有害物質の溶出が原料石炭灰ＦＡの有効活用を阻害している。すなわち、微量有害物質の溶出が抑えられれば、原料石炭灰ＦＡをより有効に活用できる。
<Elution of trace toxic substances>
In the elution test of trace hazardous substances, the elution amount of trace hazardous substances from iron-type hydrated coal ash HFAFe and hydrated coal ash HFA itself is measured. The raw material coal ash FA contains a trace amount of harmful substances such as hexavalent chromium and arsenic, and the elution of the trace amount of harmful substances hinders the effective utilization of the raw material coal ash FA. That is, the raw material coal ash FA can be used more effectively if the elution of a trace amount of harmful substances is suppressed.
微量有害物質の溶出試験結果を図１１に示す。微量有害物質として、鉛、六価クロム、砒素、セレン、フッ素、ホウ素を対象とした。そして、鉛の分析は、ＪＩＳ_Ｋ０１０２_５４．３（ＩＣＰ発光分光分析法）に準拠して行った。六価クロムの分析は、ＪＩＳ_Ｋ０１０２_６５．２．１（ジフェニルカルバジド吸光光度法）に準拠して行った。砒素の分析は、ＪＩＳ_Ｋ０１０２_６１．２（水素化物発生原子吸光法）に準拠して行った。セレンの分析は、ＪＩＳ_Ｋ０１０２_６７．２（水素化合物発生原子吸光法）に準拠して行った。フッ素の分析は、ＪＩＳ_Ｋ０１０２_３４．１（ランタン−アリザリンコンプレキソ吸光光度法）に準拠して行った。ホウ素の分析は、ＪＩＳ_Ｋ０１０２_４３．７（ＩＣＰ発光分光分析法）に準拠して行った。 FIG. 11 shows the results of the elution test of trace harmful substances. As trace harmful substances, lead, hexavalent chromium, arsenic, selenium, fluorine and boron were targeted. And the analysis of lead was performed based on JIS_K0102_54.3 (ICP emission spectroscopic analysis method). The analysis of hexavalent chromium was performed according to JIS_K0102_65.2.1 (diphenylcarbazide absorptiometry). The analysis of arsenic was performed according to JIS_K0102_61.2 (hydride generation atomic absorption method). The analysis of selenium was performed in accordance with JIS_K0102-67.2 (hydrogen compound generation atomic absorption method). The analysis of fluorine was performed based on JIS_K0102_34.1 (lanthanum-alizarin complexophotometric method). The analysis of boron was performed according to JIS_K0102_43.7 (ICP emission spectroscopy).
鉛に関し、原料石炭灰ＦＡ、鉄型水和石炭灰ＨＦＡＦｅ（１）、及び、鉄型水和石炭灰ＨＦＡＦｅ（２）のいずれも検出されなかった。これに対し、水和石炭灰ＨＦＡでは、極めて微量（０．００５ｍｇ／Ｌ）の鉛が検出された。原料石炭灰ＦＡでは検出されなかった鉛が水和石炭灰ＨＦＡで検出された理由としては、石炭灰の表面に多数のシラノール基が形成されたことで石炭灰の表面が粗になり、石炭灰の内部に閉じ込められていた鉛が溶出したことが考えられる。 Regarding lead, none of raw material coal ash FA, iron-type hydrated coal ash HFAFe (1), and iron-type hydrated coal ash HFAFe (2) was detected. On the other hand, a very small amount (0.005 mg / L) of lead was detected in the hydrated coal ash HFA. The reason why lead that was not detected in the raw coal ash FA was detected in the hydrated coal ash HFA was that the surface of the coal ash became rough due to the formation of a large number of silanol groups on the surface of the coal ash. It is thought that lead that had been trapped inside the leached out.
六価クロムに関し、原料石炭灰ＦＡでは微量（０．０４ｍｇ／Ｌ）の六価クロムが検出された。これに対し、水和石炭灰ＨＦＡ、鉄型水和石炭灰ＨＦＡＦｅ（１）、及び、鉄型水和石炭灰ＨＦＡＦｅ（２）のいずれも、六価クロムは検出されなかった。 Regarding hexavalent chromium, a very small amount (0.04 mg / L) of hexavalent chromium was detected in the raw coal ash FA. On the other hand, hexavalent chromium was not detected in any of hydrated coal ash HFA, iron-type hydrated coal ash HFAFe (1), and iron-type hydrated coal ash HFAFe (2).
砒素に関し、原料石炭灰ＦＡでは微量（０．００８ｍｇ／Ｌ）の砒素が検出され、水和石炭灰ＨＦＡでは原料石炭灰ＦＡよりも多くの量（０．５３ｍｇ／Ｌ）の砒素が検出された。これに対し、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）のいずれも砒素は検出されなかった。鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）で砒素が検出されなかった理由としては、石炭灰の表面に形成された官能基（Ｓｉ−Ｏ−Ｆｅ）が砒素を吸着したことが考えられる。一方、水和石炭灰ＨＦＡの砒素溶出量が原料石炭灰ＦＡの砒素溶出量よりも増えた理由としては、石炭灰の表面に多数のシラノール基が形成されたことで石炭灰の表面が粗になり、石炭灰の内部に閉じ込められていた砒素が溶出したこと、及び、石炭灰の表面に形成されたシラノール基には砒素の吸着能が殆どなかったことが考えられる。 Regarding arsenic, a trace amount (0.008 mg / L) of arsenic was detected in raw coal ash FA, and a larger amount (0.53 mg / L) of arsenic was detected in hydrated coal ash HFA than raw coal ash FA. . On the other hand, arsenic was not detected in either iron-type hydrated coal ash HFAFe (1) or (2). The reason why arsenic was not detected in iron-type hydrated coal ash HFAFe (1) and (2) is that the functional group (Si-O-Fe) formed on the surface of coal ash adsorbed arsenic. It is done. On the other hand, the reason why the arsenic elution amount of the hydrated coal ash HFA increased more than the arsenic elution amount of the raw material coal ash FA was that the surface of the coal ash became rough due to the formation of many silanol groups on the surface of the coal ash. Thus, it is considered that the arsenic trapped inside the coal ash was eluted, and that the silanol groups formed on the surface of the coal ash had almost no arsenic adsorption ability.
セレンに関し、原料石炭灰ＦＡでは環境基準値（０．０１ｍｇ／Ｌ）を大きく越える量（０．０７６ｍｇ／Ｌ）のセレンが検出され、水和石炭灰ＨＦＡでは原料石炭灰ＦＡよりは少ないものの環境基準値を大きく越える量（０．０４５ｍｇ／Ｌ）のセレンが検出された。これに対し、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）のいずれも、セレンは検出されなかった。鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）でセレンが検出されなかった理由としては、石炭灰の表面に形成された官能基がセレンを吸着したことが考えられる。 Regarding selenium, selenium in an amount (0.076 mg / L) far exceeding the environmental standard value (0.01 mg / L) was detected in the raw coal ash FA, and the hydrated coal ash HFA was less in the environment than the raw coal ash FA. An amount of selenium (0.045 mg / L) far exceeding the reference value was detected. On the other hand, selenium was not detected in any of the iron-type hydrated coal ash HFAFe (1) and (2). The reason why selenium was not detected in the iron-type hydrated coal ash HFAFe (1) and (2) may be that the functional groups formed on the surface of the coal ash adsorbed selenium.
フッ素に関し、原料石炭灰ＦＡでは環境基準値（０．８ｍｇ／Ｌ）を越える量（０．１ｍｇ／Ｌ）のフッ素が検出された。これに対し、水和石炭灰ＨＦＡでは環境基準値未満の量（０．４１ｍｇ／Ｌ）のフッ素が検出された。また、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）のいずれも、環境基準値未満の量（０．１４ｍｇ／Ｌ，０．１８ｍｇ／Ｌ）のフッ素が検出された。鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）で水和石炭灰ＨＦＡよりもフッ素の溶出量が抑えられた理由としては、石炭灰の表面に形成された官能基がフッ素を吸着したことが考えられる。 Regarding fluorine, in raw material coal ash FA, an amount of fluorine (0.1 mg / L) exceeding the environmental standard value (0.8 mg / L) was detected. On the other hand, the amount of fluorine (0.41 mg / L) less than the environmental standard value was detected in the hydrated coal ash HFA. Further, in both iron-type hydrated coal ash HFAFe (1) and (2), fluorine was detected in an amount (0.14 mg / L, 0.18 mg / L) less than the environmental standard value. Iron type hydrated coal ash HFAFe (1), (2), the reason why the amount of fluorine elution was suppressed compared to hydrated coal ash HFA is that the functional group formed on the surface of coal ash adsorbed fluorine Can be considered.
ホウ素に関し、原料石炭灰ＦＡでは環境基準値（１ｍｇ／Ｌ）を大きく越える量（２．９ｍｇ／Ｌ）のホウ素が検出された。これに対し、水和石炭灰ＨＦＡ、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）のいずれも、検出されたホウ素は環境基準値未満の量（０．１６ｍｇ／Ｌ，０．３５ｍｇ／Ｌ，０．１５ｍｇ／Ｌ）であった。このように、ホウ素の溶出が抑えられた理由としては、水和石炭灰ＨＦＡでは表面のシラノール基により、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）では鉄型変換されずに残った一部のシラノール基により、ホウ素が吸着されたことが考えられる。 Regarding boron, in the raw material coal ash FA, an amount of boron (2.9 mg / L) that greatly exceeded the environmental standard value (1 mg / L) was detected. On the other hand, in both hydrated coal ash HFA and iron-type hydrated coal ash HFAFe (1), (2), the detected boron is an amount less than the environmental standard value (0.16 mg / L, 0.35 mg / L, 0.15 mg / L). As described above, the reason why the elution of boron was suppressed was that the hydrated coal ash HFA remained without being iron-type converted in the iron-type hydrated coal ash HFAFe (1) and (2) due to the silanol group on the surface. It is considered that boron was adsorbed by some silanol groups.
以上の溶出試験から、鉄型水和石炭灰ＨＦＡＦｅでは、鉛、六価クロム、砒素、セレン、フッ素、ホウ素といった微量有害物質の溶出を抑制できることが確認できた。これにより、原料石炭灰ＦＡを鉄型水和石炭灰ＨＦＡに変換することで、原料石炭灰ＦＡを有効に活用できるといえる。 From the above elution test, it was confirmed that iron-type hydrated coal ash HFAFe can suppress the elution of trace harmful substances such as lead, hexavalent chromium, arsenic, selenium, fluorine and boron. Thereby, it can be said that raw material coal ash FA can be effectively utilized by converting raw material coal ash FA into iron type hydrated coal ash HFA.
また、水和石炭灰ＨＦＡでは、六価クロム、フッ素、ホウ素といった微量有害物質の溶出を抑制できることが確認できた。ここで、鉛は環境基準値未満であるため、砒素やセレンについて適切な処理をすることにより、石炭灰を有効に活用できるといえる。 In addition, it was confirmed that the hydrated coal ash HFA can suppress the elution of trace amounts of harmful substances such as hexavalent chromium, fluorine and boron. Here, since lead is less than the environmental standard value, it can be said that coal ash can be effectively utilized by appropriately treating arsenic and selenium.
＜イオン交換容量について＞
陽イオン交換容量の測定は次の手順で行った。まず、０．１ｇの試料に０．５Ｍ ＣａＣｌ２水溶液を１０ｍｌ加えて攪拌後、一晩放置した。遠心分離器を用い、純水による洗浄を５回繰り返した。沈殿物に対して、８０％エタノール水溶液による洗浄を、上澄み液中に硝酸銀水溶液でＣｌ−が検出されなくなるまで、繰り返し行った。次に、１Ｍ ＮＨ４Ｃｌ水溶液を１０ｍｌ加えて遠心分離し、上澄み液を回収する作業を５回繰り返して行った。回収した上澄み液に含まれるカルシウムイオン濃度を原子吸光光度計で測定し、陽イオン交換容量とした。なお、陽イオン交換容量の単位は〔ｃｍｏｌ・ｋｇ−１〕である。
<About ion exchange capacity>
The cation exchange capacity was measured according to the following procedure. First, 10 ml of a 0.5 M CaCl 2 aqueous solution was added to a 0.1 g sample, stirred, and allowed to stand overnight. Washing with pure water was repeated 5 times using a centrifuge. The precipitate was repeatedly washed with an 80% ethanol aqueous solution until Cl − was not detected in the supernatant with an aqueous silver nitrate solution. Next, 10 ml of 1M NH 4 Cl aqueous solution was added and centrifuged, and the operation of recovering the supernatant was repeated 5 times. The calcium ion concentration contained in the collected supernatant was measured with an atomic absorption photometer to obtain a cation exchange capacity. The unit of the cation exchange capacity is [cmol · kg −1 ].
陰イオン交換容量の測定は次の手順で行った。まず、０．５ｇの試料を５０ｍｌ遠心分離器管に入れ、３０ｍｌの１Ｍ ＮａＣｌ水溶液を加えて２時間振とうした。１５分間ほど３５００ｒｐｍの回転数で遠心分離し、上澄みを捨てた。３０ｍｌの１Ｍ ＮａＣｌを再び加え、２時間ほど振とうし、上澄みを捨てた。この操作をもう一度繰り返した。濃度８０％のエタノールで３回ほど洗浄して、過剰のＮａＣｌを除去した。３０ｍｌの１Ｍ ＮＨ４ＮＯ３水溶液を加えて１時間振とうし、遠心分離法で上澄みを分離した後、１００ｍｌ容のメスフラスコに入れた。この操作を２回繰り返した。純水で１００ｍｌに調整した後、原子吸光光度計により、硝酸アンモニウム水溶液中に出てきたナトリウムイオンの量を測定し、陰イオン交換容量とした。なお、陰イオン交換容量の単位も〔ｃｍｏｌ・ｋｇ−１〕である。 The anion exchange capacity was measured by the following procedure. First, 0.5 g of a sample was placed in a 50 ml centrifuge tube, 30 ml of 1 M NaCl aqueous solution was added, and the mixture was shaken for 2 hours. Centrifugation was carried out at 3500 rpm for about 15 minutes, and the supernatant was discarded. 30 ml of 1M NaCl was added again and shaken for about 2 hours, and the supernatant was discarded. This operation was repeated once more. Excess NaCl was removed by washing 3 times with 80% ethanol. 30 ml of 1M NH 4 NO 3 aqueous solution was added and shaken for 1 hour, and the supernatant was separated by centrifugation, and then placed in a 100 ml volumetric flask. This operation was repeated twice. After adjusting to 100 ml with pure water, the amount of sodium ions that came out in the aqueous ammonium nitrate solution was measured by an atomic absorption photometer to obtain an anion exchange capacity. The unit of the anion exchange capacity is also [cmol · kg −1 ].
図１２（ａ）は各試料の陽イオン交換容量を、図１２（ｂ）は各試料の陰イオン交換容量をそれぞれ示す。 FIG. 12A shows the cation exchange capacity of each sample, and FIG. 12B shows the anion exchange capacity of each sample.
陽イオン交換容量に関し、原料石炭灰ＦＡは７．１であり、水和石炭灰ＨＦＡは８１．６であった。鉄担持処理石炭灰（１）は６．８であり、鉄担持処理石炭灰（２）は５．９であった。鉄型水和石炭灰ＨＦＡＦｅ（１）は６１．７であり、鉄型水和石炭灰ＨＦＡＦｅ（２）は３８．８であった。一方、陰イオン交換容量に関し、原料石炭灰ＦＡは０．８であり、水和石炭灰ＨＦＡは１．３であった。鉄担持処理石炭灰（１）は２１．５であり、鉄担持処理石炭灰（２）は４４．１であった。鉄型水和石炭灰ＨＦＡＦｅ（１）は４６．３であり、鉄型水和石炭灰ＨＦＡＦｅ（２）は１８１．７であった。 Regarding the cation exchange capacity, the raw coal ash FA was 7.1 and the hydrated coal ash HFA was 81.6. The iron-supported treated coal ash (1) was 6.8, and the iron-supported treated coal ash (2) was 5.9. The iron type hydrated coal ash HFAFe (1) was 61.7, and the iron type hydrated coal ash HFAFe (2) was 38.8. On the other hand, regarding the anion exchange capacity, the raw coal ash FA was 0.8 and the hydrated coal ash HFA was 1.3. The iron-supported treated coal ash (1) was 21.5, and the iron-supported treated coal ash (2) was 44.1. The iron-type hydrated coal ash HFAFe (1) was 46.3, and the iron-type hydrated coal ash HFAFe (2) was 181.7.
原料石炭灰ＦＡと水和石炭灰ＨＦＡの陽イオン交換容量を比較すると、水和石炭灰ＨＦＡの陽イオン交換容量は、原料石炭灰ＦＡの陽イオン交換容量の１２倍弱であった。すなわち、原料石炭灰ＦＡを亜臨界水処理することで、陽イオン交換容量が大きく増加するといえる。これは、水和石炭灰ＨＦＡの表面に多数のシラノール基が形成されていることによる。シラノール基は、プロトンを放出して負に帯電するため、正電荷を有する陽イオンを保持できる。これにより、陽イオン交換容量が大きく増加していると考えられる。 Comparing the cation exchange capacity of the raw coal ash FA and the hydrated coal ash HFA, the cation exchange capacity of the hydrated coal ash HFA was slightly less than 12 times the cation exchange capacity of the raw coal ash FA. That is, it can be said that the cation exchange capacity is greatly increased by treating the raw coal ash FA with subcritical water. This is because many silanol groups are formed on the surface of the hydrated coal ash HFA. Since the silanol group releases a proton and is negatively charged, it can hold a positively charged cation. Thereby, it is considered that the cation exchange capacity is greatly increased.
水和石炭灰ＨＦＡと鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）の陽イオン交換容量を比較すると、鉄型水和石炭灰ＨＦＡＦｅ（１）の陽イオン交換容量は、水和石炭灰ＨＦＡの陽イオン交換容量の３／４程度であった。また、鉄型水和石炭灰ＨＦＡＦｅ（２）の陽イオン交換容量は、水和石炭灰ＨＦＡの陽イオン交換容量の１／２弱であった。これは、鉄型変換の過程で、水和石炭灰ＨＦＡが有する一部のシラノール基に対してヒドロキシ鉄イオンが結合し、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成したためと考えられる。すなわち、ヒドロキシ鉄イオンの結合によって負電荷の帯電量が少なくなり、水和石炭灰ＨＦＡよりも陽イオン交換容量が減少したと考えられる。 Comparing the cation exchange capacity of hydrated coal ash HFA and iron-type hydrated coal ash HFAFe (1), (2), the cation exchange capacity of iron-type hydrated coal ash HFAFe (1) is It was about 3/4 of the cation exchange capacity of HFA. Moreover, the cation exchange capacity of the iron-type hydrated coal ash HFAFe (2) was a little less than ½ of the cation exchange capacity of the hydrated coal ash HFA. This is thought to be because, during the iron-type conversion, hydroxy iron ions were bonded to some silanol groups of the hydrated coal ash HFA to form a Si—O—Fe—OH linked structure. That is, it is considered that the amount of negative charge is reduced by the binding of hydroxy iron ions, and the cation exchange capacity is reduced as compared with hydrated coal ash HFA.
鉄担持処理石炭灰（１）、（２）と鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）の陽イオン交換容量を比較すると、鉄型水和石炭灰ＨＦＡＦｅ（１）の陽イオン交換容量は、鉄担持処理石炭灰（１）の陽イオン交換容量のほぼ９倍であり、鉄型水和石炭灰ＨＦＡＦｅ（２）の陽イオン交換容量は、鉄担持処理石炭灰（２）の陽イオン交換容量の約６．５倍である。鉄担持処理石炭灰（１）、（２）は、原料石炭灰ＦＡとヒドロキシ鉄イオンとが単に混ぜられただけと考えられ、ヒドロキシ鉄イオンそのものの吸着能が現れたと解される。このことから、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）の陽イオン交換容量は、鉄担持処理石炭灰（１）、（２）の陽イオン交換容量よりも顕著な差を有していることが理解できる。 Comparing the cation exchange capacity of iron-supported coal ash (1), (2) and iron-type hydrated coal ash HFAFe (1), (2), cation exchange of iron-type hydrated coal ash HFAFe (1) The capacity is about 9 times the cation exchange capacity of the iron-supported coal ash (1), and the cation exchange capacity of the iron-type hydrated coal ash HFAFe (2) is the cation exchange capacity of the iron-supported coal ash (2). About 6.5 times the ion exchange capacity. It is considered that the iron-supported coal ash (1) and (2) is simply a mixture of the raw material coal ash FA and the hydroxy iron ion, and the adsorption ability of the hydroxy iron ion itself appears. From this, the cation exchange capacity of the iron-type hydrated coal ash HFAFe (1), (2) has a marked difference from the cation exchange capacity of the iron-supported treated coal ash (1), (2). I can understand that.
陰イオン交換容量に関しては、原料石炭灰ＦＡと水和石炭灰ＨＦＡのいずれも低い値を示している。水和石炭灰ＨＦＡの陰イオン交換容量が原料石炭灰ＦＡの陰イオン交換容量よりも僅かに高い理由は、亜臨界水処理によって石炭灰の表面に僅かに生じたアミノール基（Ａｌ−ＯＨ）によると考えられる。原料石炭灰ＦＡにおいて、Ａｌの含有量はＳｉよりも十分に少ないため、亜臨界水処理によって生じるアミノール基はシラノール基よりも少ない。そして、アミノール基によって負電荷を帯びた陰イオンが保持されるので、陰イオン交換容量が僅かに増加していると考えられる。 Regarding the anion exchange capacity, both the raw coal ash FA and the hydrated coal ash HFA show low values. The reason why the anion exchange capacity of the hydrated coal ash HFA is slightly higher than the anion exchange capacity of the raw coal ash FA is due to the aminol group (Al-OH) generated slightly on the surface of the coal ash by the subcritical water treatment. it is conceivable that. In the raw material coal ash FA, the content of Al is sufficiently smaller than that of Si, so that the aminol group generated by the subcritical water treatment is less than the silanol group. Then, since the negatively charged anion is retained by the aminol group, it is considered that the anion exchange capacity is slightly increased.
水和石炭灰ＨＦＡと鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）の陰イオン交換容量を比較すると、鉄型水和石灰ＨＦＡＦｅ（１）の陰イオン交換容量は水和石炭灰ＨＦＡの陰イオン交換容量の３５倍強であり、鉄型水和石炭灰ＨＦＡＦｅ（２）の陰イオン交換容量は水和石炭灰ＨＦＡの陰イオン交換容量の１４０倍弱であった。すなわち、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）は、水和石炭灰ＨＦＡよりも十分に高い陰イオン交換容量を有しているといえる。 Comparing the anion exchange capacity of hydrated coal ash HFA and iron-type hydrated coal ash HFAFe (1), (2), the anion exchange capacity of iron-type hydrated lime HFAFe (1) is that of hydrated coal ash HFA. The anion exchange capacity was slightly more than 35 times the anion exchange capacity, and the anion exchange capacity of the iron-type hydrated coal ash HFAFe (2) was slightly less than 140 times the anion exchange capacity of the hydrated coal ash HFA. That is, it can be said that the iron-type hydrated coal ash HFAFe (1) and (2) have a sufficiently higher anion exchange capacity than the hydrated coal ash HFA.
鉄担持処理石炭灰（１）、（２）と鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）の陰イオン交換容量を比較すると、鉄型水和石炭灰ＨＦＡＦｅ（１）の陰イオン交換容量は、鉄担持処理石炭灰（１）の陽イオン交換容量の２倍強であり、鉄型水和石炭灰ＨＦＡＦｅ（２）の陰イオン交換容量は、鉄担持処理石炭灰（２）の陰イオン交換容量のほぼ４倍である。 Comparing the anion exchange capacity of iron-supported coal ash (1), (2) and iron-type hydrated coal ash HFAFe (1), (2), anion exchange of iron-type hydrated coal ash HFAFe (1) The capacity is slightly more than twice the cation exchange capacity of the iron-supported coal ash (1), and the anion exchange capacity of the iron-type hydrated coal ash HFAFe (2) is that of the iron-supported coal ash (2). It is almost 4 times the ion exchange capacity.
鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）及び鉄担持処理石炭灰（１）、（２）にて、水和石炭灰ＨＦＡ等よりも陰イオン交換容量が高くなった理由は、ヒドロキシ鉄イオンが有するＦｅ−ＯＨ基の作用と考えられる。Ｆｅ−ＯＨ基は、プロトンを抱え込んで正に帯電するので、負電荷を有する陰イオンを保持したものと考えられる。 The reason why the anion exchange capacity of iron-type hydrated coal ash HFAFe (1), (2) and iron-supported treated coal ash (1), (2) is higher than that of hydrated coal ash HFA is This is considered to be the effect of Fe—OH groups possessed by iron ions. Since the Fe—OH group is positively charged by holding a proton, it is considered that an anion having a negative charge is retained.
そして、鉄型水和石炭灰ＨＦＡＦｅ（１）の陽イオン交換容量は、鉄担持処理石炭灰（１）の陽イオン交換容量よりも大きく、鉄型水和石炭灰ＨＦＡＦｅ（２）の陽イオン交換容量は鉄担持処理石炭灰（２）の陽イオン交換容量よりも際だって大きい。前述したように、鉄担持処理石炭灰（１）、（２）では、ヒドロキシ鉄イオンそのものの吸着能が発現したものと解される。そして、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）では、水和石炭灰ＨＦＡが有するシラノール基に対してヒドロキシ鉄イオンが結合し、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成しているので、鉄担持処理石炭灰（１）、（２）よりもＦｅ−ＯＨ基の数が増えていると考えられる。 The cation exchange capacity of the iron-type hydrated coal ash HFAFe (1) is larger than the cation exchange capacity of the iron-supported treated coal ash (1), and the cation exchange of the iron-type hydrated coal ash HFAFe (2). The capacity is remarkably larger than the cation exchange capacity of iron-supported treated coal ash (2). As described above, it is understood that the iron-supporting treated coal ash (1) and (2) has developed the ability to adsorb hydroxy iron ions themselves. And in iron type hydrated coal ash HFAFe (1) and (2), a hydroxy iron ion couple | bonds with the silanol group which hydrated coal ash HFA has, and forms the connection structure of Si-O-Fe-OH. Therefore, it is considered that the number of Fe—OH groups is increased as compared with iron-supported coal ash (1) and (2).
この結果より、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）は、効果的な陰イオン交換材になることが判る。 From this result, it can be seen that iron-type hydrated coal ash HFAFe (1), (2) is an effective anion exchange material.
＜吸着試験について＞
前述の溶出試験では、鉄型水和石炭灰ＨＦＡＦｅや水和石炭灰ＨＦＡそのものからの微量有害物質の溶出を確認した。ここで、鉄型水和石炭灰ＨＦＡＦｅは、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造中のＦｅ−ＯＨ基が陰イオンや陽イオンを吸着する。そこで、鉄型水和石炭灰ＨＦＡＦｅの吸着材としての適性を確認する目的で、吸着試験を行った。本実施形態の吸着試験は、全クロム、砒素、及び、リン酸イオンについて行った。
<About adsorption test>
In the elution test described above, elution of trace amounts of harmful substances from iron-type hydrated coal ash HFAFe and hydrated coal ash HFA itself was confirmed. Here, in the iron-type hydrated coal ash HFAFe, the Fe—OH group in the Si—O—Fe—OH linked structure adsorbs anions and cations. Therefore, an adsorption test was conducted for the purpose of confirming the suitability of iron-type hydrated coal ash HFAFe as an adsorbent. The adsorption test of this embodiment was conducted for all chromium, arsenic, and phosphate ions.
図１３（ａ）、（ｂ）は、全クロムの吸着試験結果を示す。イニシャル試験では、試料溶液中の全クロム濃度を測定した。全クロムの濃度測定は、日本工業規格ＪＩＳ_Ｋ０１０２_６５．１．５（ＩＣＰ質量分析法）に準拠して行った。吸着試験では、鉄型水和石炭灰ＨＦＡＦｅを試料溶液中に所定量添加する工程、鉄型水和石炭灰ＨＦＡＦｅを添加した試料溶液を、所定時間に亘って振とうする工程、振とう後の試料溶液に遠心分離を行って固液を分離する工程、上澄み液を濾別する工程、上澄み液中の全クロム濃度を測定する工程を行った。 FIGS. 13A and 13B show the adsorption test results for all chromium. In the initial test, the total chromium concentration in the sample solution was measured. The total chromium concentration was measured in accordance with Japanese Industrial Standard JIS_K0102_65.1.5 (ICP mass spectrometry). In the adsorption test, a step of adding a predetermined amount of iron-type hydrated coal ash HFAFe to the sample solution, a step of shaking the sample solution to which the iron-type hydrated coal ash HFAFe has been added for a predetermined time, The sample solution was centrifuged to separate the solid and liquid, the supernatant was filtered off, and the total chromium concentration in the supernatant was measured.
なお、鉄型水和石炭灰ＨＦＡＦｅは、前述の鉄型水和石炭灰ＨＦＡＦｅ（２）を用いた。また、鉄型水和石炭灰ＨＦＡＦｅは試料溶液１Ｌに対して１ｇを添加した。振とうは２０時間に亘って行った。 In addition, the iron type hydrated coal ash HFAFe (2) described above was used as the iron type hydrated coal ash HFAFe. Further, 1 g of iron-type hydrated coal ash HFAFe was added to 1 L of the sample solution. Shaking was performed for 20 hours.
また、上記のイニシャル試験及び吸着試験を、ｐＨ７とｐＨ１０の試料溶液のそれぞれについて行った。そして、全クロムの初期濃度を２．０ｍｇ／Ｌ、４．０ｍｇ／Ｌ、８．０ｍｇ／Ｌ、１０．０ｍｇ／Ｌ、２５．０ｍｇ／Ｌ、５０．０ｍｇ／Ｌ、１００．０ｍｇ／Ｌ、１５０．０ｍｇ／Ｌ、２００．０ｍｇ／Ｌに調整したものを用意した。 Further, the initial test and the adsorption test described above were performed for each of the pH 7 and pH 10 sample solutions. The initial concentration of total chromium is 2.0 mg / L, 4.0 mg / L, 8.0 mg / L, 10.0 mg / L, 25.0 mg / L, 50.0 mg / L, 100.0 mg / L, What adjusted to 150.0 mg / L and 200.0 mg / L was prepared.
そして、イニシャル試験での全クロム濃度と吸着試験での全クロム濃度とから、各試料溶液について全クロムの除去率を求めた。 And the removal rate of the total chromium was calculated | required about each sample solution from the total chromium density | concentration in an initial test, and the total chromium density | concentration in an adsorption test.
ｐＨ７の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は５２．４％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は１３．５％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は０．７％であった。ｐＨ１０の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は１９．０％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は１４．０％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は１．７％であった。 In the case of pH 7, the removal rate with a sample solution with a concentration of 2.0 mg / L is 52.4%, the removal rate with a sample solution with a concentration of 10.0 mg / L is 13.5%, and the sample with a concentration of 200.0 mg / L The removal rate in solution was 0.7%. In the case of pH 10, the removal rate with a sample solution with a concentration of 2.0 mg / L is 19.0%, the removal rate with a sample solution with a concentration of 10.0 mg / L is 14.0%, and the sample with a concentration of 200.0 mg / L The removal rate with the solution was 1.7%.
ｐＨ７とｐＨ１０のいずれも、試料溶液中の全クロム濃度が高くなると除去率が下がる傾向が見られた。これは、鉄型水和石炭灰ＨＦＡＦｅによるカドミウムの吸着量が飽和したことが原因として考えられる。すなわち、鉄型水和石炭灰ＨＦＡＦｅが吸着した全クロム量は大きく変わらないと考えられる。上記の試験では、試料溶液１Ｌに対して鉄型水和石炭灰ＨＦＡＦｅを１ｇしか添加していない。添加量が少ないことを考慮すれば、鉄型水和石炭灰ＨＦＡＦｅは全クロムに対して実用上十分な吸着能を有しているといえる。言い換えれば、鉄型水和石炭灰ＨＦＡＦｅの添加量を増やすことで、高濃度の試料溶液であっても十分な除去率が得られ、全クロムに対する吸着材として実用性を有すると考えられる。 At both pH 7 and pH 10, the removal rate tended to decrease as the total chromium concentration in the sample solution increased. This is considered to be because the adsorption amount of cadmium by the iron-type hydrated coal ash HFAFe was saturated. That is, it is considered that the total chromium amount adsorbed by the iron-type hydrated coal ash HFAFe does not change greatly. In the above test, only 1 g of iron-type hydrated coal ash HFAFe is added to 1 L of the sample solution. Considering that the addition amount is small, it can be said that iron-type hydrated coal ash HFAFe has a practically sufficient adsorptive capacity for all chromium. In other words, by increasing the amount of iron-type hydrated coal ash HFAFe added, a sufficient removal rate can be obtained even with a high-concentration sample solution, which is considered to have practicality as an adsorbent for all chromium.
ｐＨ７とｐＨ１０の結果を比較すると、ｐＨ１０での除去率はｐＨ７での除去率よりも低く、試料濃度が２．０〜１０．０ｍｇ／Ｌに亘って除去率は１９．０〜１４．０％の範囲に収まっている。これは、試料溶液をアルカリ性にしたことで、Ｆｅ−ＯＨ基がプロトンを抱え込み難くなったことが一因として考えられる。 Comparing the results of pH 7 and pH 10, the removal rate at pH 10 is lower than the removal rate at pH 7, and the removal rate is 19.0 to 14.0% over a sample concentration of 2.0 to 10.0 mg / L. It is in the range. One possible reason for this is that the Fe—OH group has become difficult to carry protons by making the sample solution alkaline.
図１４（ａ）、（ｂ）は、鉄型水和石炭灰ＨＦＡＦｅ（１）を用いた際の砒素の吸着試験結果を、図１５（ａ）、（ｂ）は、鉄型水和石炭灰ＨＦＡＦｅ（２）を用いた際の砒素の吸着試験結果をそれぞれ示す。手順は全クロムの試験と同様であるので省略する。なお、砒素の濃度測定は、日本工業規格ＪＩＳ_Ｋ０１０２_６１．４（ＩＣＰ質量分析法）に準拠して行った。 FIGS. 14A and 14B show the arsenic adsorption test results when using iron-type hydrated coal ash HFAFe (1), and FIGS. 15A and 15B show the iron-type hydrated coal ash. The arsenic adsorption test results when HFAFe (2) is used are shown. The procedure is the same as the test for all chromium, and will be omitted. The arsenic concentration was measured according to Japanese Industrial Standard JIS_K0102_61.4 (ICP mass spectrometry).
鉄型水和石炭灰ＨＦＡＦｅ（１）に関し、ｐＨ７の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は８０．０％、濃度４．０ｍｇ／Ｌの試料溶液での除去率は４８．８％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は２２．１％、濃度２５．０ｍｇ／Ｌの試料溶液での除去率は８．５％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は−０．４％であった。ｐＨ１０の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は４５．０％、濃度４．０ｍｇ／Ｌの試料溶液での除去率は２６．８％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は１４．７％、濃度２５．０ｍｇ／Ｌの試料溶液での除去率は４．７％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は１．４％であった。 Regarding the iron-type hydrated coal ash HFAFe (1), when the pH is 7, the removal rate in the sample solution having a concentration of 2.0 mg / L is 80.0%, and the removal rate in the sample solution having a concentration of 4.0 mg / L is 48. The removal rate with a sample solution of .8% and a concentration of 10.0 mg / L is 22.1%, the removal rate with a sample solution of a concentration of 25.0 mg / L is 8.5%, and a sample with a concentration of 200.0 mg / L The removal rate in solution was -0.4%. In the case of pH 10, the removal rate with a sample solution with a concentration of 2.0 mg / L is 45.0%, the removal rate with a sample solution with a concentration of 4.0 mg / L is 26.8%, and a sample with a concentration of 10.0 mg / L The removal rate in the solution was 14.7%, the removal rate in the sample solution with a concentration of 25.0 mg / L was 4.7%, and the removal rate with a sample solution with a concentration of 200.0 mg / L was 1.4%. It was.
ｐＨ７とｐＨ１０のいずれも、試料溶液中の砒素濃度が高くなると除去率が下がる傾向が見られた。これも、鉄型水和石炭灰ＨＦＡＦｅによる砒素の吸着量が飽和したことが原因として考えられる。全クロムと比較した場合、砒素では低濃度での除去率が高いこと、ｐＨが変わっても十分な除去率が得られていることが判る。 At both pH 7 and pH 10, the removal rate tended to decrease as the arsenic concentration in the sample solution increased. This is also considered to be because the amount of arsenic adsorption by the iron-type hydrated coal ash HFAFe is saturated. When compared with total chromium, it can be seen that arsenic has a high removal rate at a low concentration and that a sufficient removal rate is obtained even when the pH changes.
鉄型水和石炭灰ＨＦＡＦｅ（２）に関し、ｐＨ７の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は１００．０％、濃度４．０ｍｇ／Ｌの試料溶液での除去率は７５．６％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は２９．８％、濃度２５．０ｍｇ／Ｌの試料溶液での除去率は１２．０％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は０．３％であった。ｐＨ１０の場合、濃度２．０ｍｇ／Ｌの試料溶液での除去率は７５．０％、濃度４．０ｍｇ／Ｌの試料溶液での除去率は３９．０％、濃度１０．０ｍｇ／Ｌの試料溶液での除去率は１６．７％、濃度２５．０ｍｇ／Ｌの試料溶液での除去率は９．０％、濃度２００．０ｍｇ／Ｌの試料溶液での除去率は０．８％であった。 Regarding the iron-type hydrated coal ash HFAFe (2), when the pH is 7, the removal rate in the sample solution having a concentration of 2.0 mg / L is 100.0%, and the removal rate in the sample solution having a concentration of 4.0 mg / L is 75 The removal rate with a sample solution of .6% and a concentration of 10.0 mg / L is 29.8%, the removal rate with a sample solution of a concentration of 25.0 mg / L is 12.0%, and a sample with a concentration of 200.0 mg / L The removal rate in the solution was 0.3%. In the case of pH 10, the removal rate with a sample solution with a concentration of 2.0 mg / L is 75.0%, the removal rate with a sample solution with a concentration of 4.0 mg / L is 39.0%, and a sample with a concentration of 10.0 mg / L The removal rate in the solution was 16.7%, the removal rate in the sample solution with a concentration of 25.0 mg / L was 9.0%, and the removal rate with a sample solution with a concentration of 200.0 mg / L was 0.8%. It was.
ｐＨ７とｐＨ１０のいずれも、試料溶液中の砒素濃度が高くなると除去率が下がる傾向が見られた。鉄型水和石炭灰ＨＦＡＦｅ（１）と比較した場合、全体的に除去率が高くなっているが、これは、表面に形成されているＦｅ−ＯＨ基が増えていることが一因と考えられる。 At both pH 7 and pH 10, the removal rate tended to decrease as the arsenic concentration in the sample solution increased. When compared with iron-type hydrated coal ash HFAFe (1), the overall removal rate is high, but this is thought to be due to an increase in Fe-OH groups formed on the surface. It is done.
この試験でも、試料溶液１Ｌに対して鉄型水和石炭灰ＨＦＡＦｅを１ｇしか添加していない。添加量が少ないことを考慮すれば、鉄型水和石炭灰ＨＦＡＦｅは砒素に対しても十分な吸着能を有し、砒素に対する吸着材として十分実用性を有すると考えられる。 Also in this test, only 1 g of iron-type hydrated coal ash HFAFe is added to 1 L of the sample solution. Considering that the addition amount is small, it is considered that iron-type hydrated coal ash HFAFe has a sufficient adsorption capacity for arsenic and is sufficiently practical as an adsorbent for arsenic.
図１６は、リン酸イオンの吸着測定結果を示す。リン酸イオンの吸着測定では、０．５ｇの試料を容積２００ｍｌのポリビンに取り、ＮａＨ２ＰＯ４溶液、ＮａＣｌ溶液を加えて、合計の容量が１００ｍｌになるように、さらに純水を加えた。この時のリン酸濃度（初期濃度）を１０ｍＭに調整し、ＮａＣｌの濃度を１０ｍＭとして、ｐＨを７に調節した。２４時間振とうした後に、遠心分離法（回転数３５００ｒｐｍ，時間２０分間）にて、上澄みを得た。上澄み中のリンを比色法によって測定した。 FIG. 16 shows the measurement results of phosphate ion adsorption. In the measurement of phosphate ion adsorption, 0.5 g of a sample was taken in a 200 ml-volume polybin, and NaH 2 PO 4 solution and NaCl solution were added, and pure water was further added so that the total volume became 100 ml. At this time, the phosphoric acid concentration (initial concentration) was adjusted to 10 mM, the NaCl concentration was adjusted to 10 mM, and the pH was adjusted to 7. After shaking for 24 hours, a supernatant was obtained by centrifugation (rotation speed 3500 rpm, time 20 minutes). The phosphorus in the supernatant was measured by a colorimetric method.
この比色法で用いる試薬について説明する。試薬として、混合試薬、モリブデン酸アモニウム溶液、リン酸標準液を準備した。混合試薬は、試薬Ａと試薬Ｂを混合することで得た。試薬Ａは、１０ｇのアスコルビン酸を純水９０ｍｌに溶解した１０％のアスコルビン酸水溶液を用いた。試薬Ｂは、０．６６７ｇのPotassium antimony tartrate（ＫＳｂＯＣ４Ｈ４Ｏ６：酒石酸アンチモンカリウム）を純水２５０ｍｌに溶解したものを用いた。そして、使用する直前に試薬Ａと試薬Ｂのそれぞれを同じ量混合して混合試薬とした。モリブデン酸アモニウム溶液は、８．７４ｍＭのものを用いた。この溶液は、モリブデン酸アモニウム９．６ｇを量って取り、純水で溶かして１リットルにすることで得た。リン酸標準液は、５ｍＭ リン酸カリウム（ＫＨ２ＰＯ４）水溶液を用いた。 The reagent used in this colorimetric method will be described. As reagents, a mixed reagent, an ammonium molybdate solution, and a phosphoric acid standard solution were prepared. The mixed reagent was obtained by mixing reagent A and reagent B. As the reagent A, a 10% ascorbic acid aqueous solution in which 10 g of ascorbic acid was dissolved in 90 ml of pure water was used. As reagent B, 0.667 g of Potassium antimony tartrate (KSbOC 4 H 4 O 6 : potassium antimony tartrate) dissolved in 250 ml of pure water was used. Then, immediately before use, the same amount of each of Reagent A and Reagent B was mixed to obtain a mixed reagent. The ammonium molybdate solution used was 8.74 mM. This solution was obtained by weighing 9.6 g of ammonium molybdate and dissolving in pure water to make 1 liter. As the phosphate standard solution, a 5 mM potassium phosphate (KH 2 PO 4 ) aqueous solution was used.
次に、比色法における測定について説明する。まず、上記のリン酸吸着試験で得られた３ｍｌの上澄みを５０ｍｌ容のメスフラスコに取った。その中に、４Ｎ 硫酸５ｍｌとモリブデン酸アモニウム溶液５ｍｌを加えて混合した。また、別の５０ｍｌメスフラスコに、リン酸標準液（リン酸カリウム水溶液）を１ｍｌ，２ｍｌ，３ｍｌほど取り、同様に試薬を加えた。次に、混合試薬を４ｍｌ入れ、さらに純水を加えて定容とした。１０分間発色させ、分光光度計で波長８８６ｎｍでの透過率を測定した。 Next, measurement in the colorimetric method will be described. First, 3 ml of the supernatant obtained in the phosphoric acid adsorption test was placed in a 50 ml volumetric flask. Into this, 5 ml of 4N sulfuric acid and 5 ml of ammonium molybdate solution were added and mixed. Further, about 1 ml, 2 ml, and 3 ml of a phosphoric acid standard solution (potassium phosphate aqueous solution) were taken into another 50 ml volumetric flask, and the reagent was added in the same manner. Next, 4 ml of the mixed reagent was added, and pure water was added to make a constant volume. The color was developed for 10 minutes, and the transmittance at a wavelength of 886 nm was measured with a spectrophotometer.
図１６に示すように、リン酸吸着量〔ｃｍｏｌ・ｋｇ−１〕に関し、鉄型水和石炭灰ＨＦＡＦｅ（１）のリン酸吸着量は３７８．４、鉄型水和石炭灰ＨＦＡＦｅ（２）のリン酸吸着量は５１４．７であった。一方、同じ条件の下で測定した鉄担持処理石炭灰（１）のリン酸吸着量は１８１．１であり、鉄担持処理石炭灰（２）のリン酸吸着量は３４２．２であった。 As shown in FIG. 16, regarding the phosphate adsorption amount [cmol · kg −1 ], the phosphate adsorption amount of iron-type hydrated coal ash HFAFe (1) is 378.4, and iron-type hydrated coal ash HFAFe (2). The amount of phosphoric acid adsorbed was 514.7. On the other hand, the phosphate adsorption amount of iron-supported coal ash (1) measured under the same conditions was 181.1, and the phosphate adsorption amount of iron-supported coal ash (2) was 342.2.
前述したように、鉄担持処理石炭灰（１）、（２）では、ヒドロキシ鉄イオンが有するＦｅ−ＯＨ基が正電荷を帯び、陰イオンであるリン酸イオンを吸着すると考えられる。同様に、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）では、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造中のＦｅ−ＯＨ基が正電荷を帯び、陰イオンであるリン酸イオンを吸着すると考えられる。 As described above, in the iron-supported coal ash (1) and (2), it is considered that the Fe—OH group of the hydroxy iron ion has a positive charge and adsorbs the phosphate ion which is an anion. Similarly, in the iron-type hydrated coal ash HFAFe (1) and (2), the Fe—OH group in the Si—O—Fe—OH linked structure is positively charged and adsorbs phosphate ions, which are anions. It is thought that.
ここで、鉄型水和石炭灰ＨＦＡＦｅ（１）のリン酸イオン吸着量は鉄担持処理石炭灰（１）のリン酸イオン吸着量のほぼ２倍であり、鉄型水和石炭灰ＨＦＡＦｅ（２）のリン酸イオン吸着量は鉄担持処理石炭灰（２）のリン酸イオン吸着量のほぼ１．５倍である。添加した鉄の量が等しいことから、鉄型水和石炭灰ＨＦＡＦｅ（１）、（２）とすることでリン酸イオンの吸着量が非常に高くなることが判る。 Here, the phosphate ion adsorption amount of the iron-type hydrated coal ash HFAFe (1) is almost twice the phosphate ion adsorption amount of the iron-supported coal ash (1), and the iron-type hydrated coal ash HFAFe (2) ) Phosphate ion adsorption amount is approximately 1.5 times the phosphate ion adsorption amount of iron-supported treated coal ash (2). Since the amount of added iron is equal, it can be seen that the amount of phosphate ions adsorbed becomes extremely high by using iron-type hydrated coal ash HFAFe (1), (2).
従って、鉄型水和石炭灰ＨＦＡＦｅは、リン酸イオンの吸着材としても実用上十分な吸着能を有すると考えられる。 Therefore, it is considered that the iron-type hydrated coal ash HFAFe has a practically sufficient adsorptive capacity as a phosphate ion adsorbent.
＜まとめ＞
以上説明したように、本実施形態の鉄型水和石炭灰ＨＦＡＦｅは、原料石炭灰ＦＡの亜臨界水処理で得られた水和石炭灰ＨＦＡに対し、ヒドロキシ鉄イオンを含んだ溶液（金属溶液）を添加することで製造できる。このため、エネルギー、材料及び設備のコスト低減に寄与する。
<Summary>
As described above, the iron-type hydrated coal ash HFAFe of this embodiment is a solution (metal solution) containing hydroxy iron ions to the hydrated coal ash HFA obtained by subcritical water treatment of the raw material coal ash FA. ) Can be added. For this reason, it contributes to the cost reduction of energy, material, and an installation.
また、上述の鉄型水和石炭灰ＨＦＡＦｅによれば、石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造を有しているので、Ｆｅ−ＯＨ基によって陰イオンを吸着させることができる。また、残存しているシラノール基によって陽イオンを吸着させることもできる。これにより、石炭灰に含まれる微量有害物質の溶出を抑制できる。例えば、砒素やセレン等の微量有害物質の溶出を抑制できる。 Moreover, according to the iron-type hydrated coal ash HFAFe described above, since the surface of the coal ash has a Si—O—Fe—OH connection structure, anions can be adsorbed by the Fe—OH group. . Further, cations can be adsorbed by the remaining silanol groups. Thereby, the elution of the trace amount harmful substance contained in coal ash can be suppressed. For example, elution of a trace amount of harmful substances such as arsenic and selenium can be suppressed.
＜変形例について＞
前述の実施形態では、ヒドロキシ鉄イオンを用いて水和石炭灰ＨＦＡを鉄型変換し、鉄型水和石炭灰ＨＦＡＦｅを生成するようにしたものを例示したが、これに限定されない。例えば、ヘキサハイドロ鉄イオンを用いて水和石炭灰ＨＦＡを鉄型変換してもよい。ここで、前述の実施形態のようにヒドロキシ鉄イオンを用いた場合には、液中に多くの鉄イオンが存在するので、シラノール基の鉄型変換を効率よく行うことができる。
<About modification>
In the above-described embodiment, the hydrated coal ash HFA is converted into an iron type by using hydroxy iron ions to generate the iron-type hydrated coal ash HFAFe. However, the present invention is not limited to this. For example, the hydrated coal ash HFA may be iron-type converted using hexahydro iron ions. Here, when hydroxy iron ions are used as in the above-described embodiment, since many iron ions exist in the liquid, the iron type conversion of the silanol group can be performed efficiently.
また、前述の実施形態では、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を石炭灰の表面に形成していたが、鉄イオンに代えてアルミニウムイオンを用い、Ｓｉ−Ｏ−Ａｌ−ＯＨの連結構造を石炭灰の表面に形成してもよい。ここで、前述の実施形態のように、Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を石炭灰の表面に形成した場合には、万一Ｆｅが溶出しても、土壌に多く含まれる元素であることから、環境上好ましい。 In the above-described embodiment, the Si—O—Fe—OH connection structure is formed on the surface of coal ash, but instead of iron ions, aluminum ions are used, and the Si—O—Al—OH connection structure is used. May be formed on the surface of the coal ash. Here, when the Si—O—Fe—OH connection structure is formed on the surface of the coal ash as in the above-described embodiment, even if Fe elutes, it is an element contained in a large amount of soil. Therefore, it is environmentally preferable.
１０ オートクレーブ
２０ 反応容器
３０ 遠心分離器
４０ 凍結乾燥機
５０ 微粉炭ボイラー
６０ 蒸気タービン
ＦＡ 石炭灰
Ｗ 水
ＨＦＡ 水和石炭灰
ＨＦＡＦｅ 鉄型水和石炭灰
10 Autoclave 20 Reaction vessel 30 Centrifugal separator 40 Freeze dryer 50 Pulverized coal boiler 60 Steam turbine FA Coal ash W Water HFA Hydrated coal ash HFAFe Iron-type hydrated coal ash
Claims (5)
Ｓｉ−Ｏ−Ｆｅ−ＯＨの連結構造を、亜臨界水処理によりシラノール基が付加された石炭灰の表面に有することを特徴とする、石炭灰を原料とする化合物。 A compound using coal ash as a raw material, which has anion adsorption capacity,
A compound using coal ash as a raw material, having a Si—O— Fe—OH linkage structure on the surface of coal ash to which a silanol group has been added by subcritical water treatment .
鉄イオンを含有する金属溶液を前記中間生成物に添加し、前記石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成する第２工程と、
を有することを特徴とする、石炭灰を原料とする化合物の製造方法。 A first step of treating the coal ash with subcritical water and producing an intermediate product having a silanol group on the surface of the coal ash;
A second step of adding a metal solution containing iron ions to the intermediate product to form a Si—O— Fe—OH connection structure on the surface of the coal ash;
A method for producing a compound using coal ash as a raw material, comprising :
ヒドロキシ鉄イオンを含有する金属溶液を前記中間生成物に添加し、前記石炭灰の表面にＳｉ−Ｏ−Ｆｅ−ＯＨの連結構造を形成することを特徴とする、請求項２に記載の、石炭灰を原料とする化合物の製造方法。 In the second step,
Adding a metal solution containing hydroxy iron ions to the intermediate product, and forming a connection structure of Si-O-Fe-OH on the surfaces of the coal ash, according to claim 2, coal A method for producing a compound using ash as a raw material .
濃度が０．０５〜０．１Ｍの塩化鉄水溶液を調整し、水酸化ナトリウム水溶液を加えてｐＨ３〜４に調整しながら、前記塩化鉄水溶液を前記中間生成物に添加することを特徴とする、請求項３に記載の、石炭灰を原料とする化合物の製造方法。 In the second step,
Adjusting the aqueous solution of iron chloride having a concentration of 0.05 to 0.1M, adding the aqueous solution of iron chloride to the intermediate product while adjusting the pH to 3 to 4 by adding an aqueous solution of sodium hydroxide, The manufacturing method of the compound of Claim 3 which uses coal ash as a raw material .
石炭灰と、水又はアルカリ性溶液との混合体を、１５０℃以上の温度で６０分以上加熱することにより、前記石炭灰を亜臨界水処理することを特徴とする請求項２から４の何れか１項に記載の、石炭灰を原料とする化合物の製造方法。 In the first step,
And coal ash, a mixture of water or an alkaline solution, by heating over 60 minutes at 0.99 ° C. or higher, claim 2 4, characterized in that the subcritical water treatment the coal ash The manufacturing method of the compound of Claim 1 which uses coal ash as a raw material .
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