JP2007007541A - Method for treating nitrate nitrogen-containing water - Google Patents
Method for treating nitrate nitrogen-containing water Download PDFInfo
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- JP2007007541A JP2007007541A JP2005191087A JP2005191087A JP2007007541A JP 2007007541 A JP2007007541 A JP 2007007541A JP 2005191087 A JP2005191087 A JP 2005191087A JP 2005191087 A JP2005191087 A JP 2005191087A JP 2007007541 A JP2007007541 A JP 2007007541A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 122
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 title claims abstract description 119
- 238000000034 method Methods 0.000 title claims abstract description 62
- 239000003054 catalyst Substances 0.000 claims abstract description 72
- 239000007789 gas Substances 0.000 claims abstract description 47
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000002245 particle Substances 0.000 claims description 52
- 229910052751 metal Inorganic materials 0.000 claims description 51
- 239000002184 metal Substances 0.000 claims description 51
- 239000010419 fine particle Substances 0.000 claims description 45
- 229910045601 alloy Inorganic materials 0.000 claims description 16
- 239000000956 alloy Substances 0.000 claims description 16
- 229910052809 inorganic oxide Inorganic materials 0.000 claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 229910052763 palladium Inorganic materials 0.000 claims description 10
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 8
- 229910052737 gold Inorganic materials 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 5
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 229910052709 silver Inorganic materials 0.000 claims description 5
- 150000002739 metals Chemical class 0.000 claims description 4
- 229910006404 SnO 2 Inorganic materials 0.000 claims description 3
- GEIAQOFPUVMAGM-UHFFFAOYSA-N ZrO Inorganic materials [Zr]=O GEIAQOFPUVMAGM-UHFFFAOYSA-N 0.000 claims description 3
- 238000003672 processing method Methods 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 description 22
- 229910052739 hydrogen Inorganic materials 0.000 description 22
- 239000003638 chemical reducing agent Substances 0.000 description 20
- 239000006185 dispersion Substances 0.000 description 15
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 15
- 230000002829 reductive effect Effects 0.000 description 15
- 238000000354 decomposition reaction Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 11
- 230000007423 decrease Effects 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 239000010949 copper Substances 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 229910002668 Pd-Cu Inorganic materials 0.000 description 5
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 239000012298 atmosphere Substances 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 239000010931 gold Substances 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000010944 silver (metal) Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- JVMRPSJZNHXORP-UHFFFAOYSA-N ON=O.ON=O.ON=O.N Chemical compound ON=O.ON=O.ON=O.N JVMRPSJZNHXORP-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 229910017464 nitrogen compound Inorganic materials 0.000 description 3
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000010457 zeolite Substances 0.000 description 3
- AZQWKYJCGOJGHM-UHFFFAOYSA-N 1,4-benzoquinone Chemical compound O=C1C=CC(=O)C=C1 AZQWKYJCGOJGHM-UHFFFAOYSA-N 0.000 description 2
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910017827 Cu—Fe Inorganic materials 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 2
- 229910018883 Pt—Cu Inorganic materials 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 238000000909 electrodialysis Methods 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 238000004108 freeze drying Methods 0.000 description 2
- 239000010842 industrial wastewater Substances 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 238000001223 reverse osmosis Methods 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 239000012279 sodium borohydride Substances 0.000 description 2
- 229910000033 sodium borohydride Inorganic materials 0.000 description 2
- 229910001379 sodium hypophosphite Inorganic materials 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000000108 ultra-filtration Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- JJLJMEJHUUYSSY-UHFFFAOYSA-L Copper hydroxide Chemical compound [OH-].[OH-].[Cu+2] JJLJMEJHUUYSSY-UHFFFAOYSA-L 0.000 description 1
- 239000005750 Copper hydroxide Substances 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 229910001252 Pd alloy Inorganic materials 0.000 description 1
- 229910021065 Pd—Fe Inorganic materials 0.000 description 1
- 229910002839 Pt-Mo Inorganic materials 0.000 description 1
- 229910018885 Pt—Au Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- -1 ammonium ions Chemical class 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910001956 copper hydroxide Inorganic materials 0.000 description 1
- XPPWAISRWKKERW-UHFFFAOYSA-N copper palladium Chemical compound [Cu].[Pd] XPPWAISRWKKERW-UHFFFAOYSA-N 0.000 description 1
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 150000002500 ions Chemical group 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- NXJCBFBQEVOTOW-UHFFFAOYSA-L palladium(2+);dihydroxide Chemical compound O[Pd]O NXJCBFBQEVOTOW-UHFFFAOYSA-L 0.000 description 1
- YJVFFLUZDVXJQI-UHFFFAOYSA-L palladium(ii) acetate Chemical compound [Pd+2].CC([O-])=O.CC([O-])=O YJVFFLUZDVXJQI-UHFFFAOYSA-L 0.000 description 1
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- OJLCQGGSMYKWEK-UHFFFAOYSA-K ruthenium(3+);triacetate Chemical compound [Ru+3].CC([O-])=O.CC([O-])=O.CC([O-])=O OJLCQGGSMYKWEK-UHFFFAOYSA-K 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical compound [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 description 1
- 229940038773 trisodium citrate Drugs 0.000 description 1
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- Treatment Of Water By Oxidation Or Reduction (AREA)
- Catalysts (AREA)
Abstract
Description
本発明は、硝酸性窒素含有水の処理方法に関し、さらに詳しくは、硝酸性窒素含有水を還元剤の存在下に触媒と接触させて硝酸性窒素を還元分解する硝酸性窒素含有水の処理方法に関する。 The present invention relates to a method for treating nitrate nitrogen-containing water, and more specifically, a method for treating nitrate nitrogen-containing water by reductively decomposing nitrate nitrogen by bringing nitrate nitrogen-containing water into contact with a catalyst in the presence of a reducing agent. About.
従来、排水等の中に含まれる硝酸性窒素を除去する処理方法としては、微生物による生物学的処理方法、吸着法、イオン交換法、逆浸透膜法、電気透析法などの物理化学的処理方法および水素などの還元剤の存在下に硝酸性窒素を触媒と接触させて還元分解する化学的処理方法などが知られている。特に、硝酸性窒素を還元剤の存在下に触媒と接触させて還元分解する化学的処理方法は低濃度の硝酸性窒素を含む飲料水の原水や高濃度の硝酸性窒素を含む工業排水など、大量の硝酸性窒素含有水から硝酸性窒素を除去するのに適しており、種々の処理方法が提案されている。 Conventional treatment methods for removing nitrate nitrogen contained in wastewater, etc. include biological treatment methods using microorganisms, adsorption methods, ion exchange methods, reverse osmosis membrane methods, electrodialysis methods, and other physicochemical treatment methods. Also known is a chemical treatment method in which nitrate nitrogen is brought into contact with a catalyst in the presence of a reducing agent such as hydrogen to perform reductive decomposition. In particular, chemical treatment methods in which nitrate nitrogen is brought into contact with a catalyst in the presence of a reducing agent for reductive decomposition include raw water for drinking water containing low concentrations of nitrate nitrogen and industrial wastewater containing high concentrations of nitrate nitrogen, etc. It is suitable for removing nitrate nitrogen from a large amount of nitrate nitrogen-containing water, and various treatment methods have been proposed.
例えば、本願出願人にかかる特開２００４−９７８９３号公報（特許文献１）には、無機酸化物担体および／またはカーボン担体に、Ｐｔ、Ａｕ、Ａｇ、Ｐｄ、Ｒｕ、Ｃｕ、Ｎｉ、Ｗ、Ｖ、Ｍｏ、Ｆｅから選ばれる１種または２種以上の金属微粒子および／または合金微粒子が担持されてなる、平均粒子径が５ｎｍ〜２０μｍの範囲にある硝酸性窒素含有水処理用触媒が記載されており、更に、硝酸性窒素含有水処理方法として、
（ａ）前述の水処理用触媒と硝酸性窒素含有水とを、還元剤の存在下で接触させる工程
（ｂ）前記接触済の硝酸性窒素含有水から水処理用触媒を分離する工程
（ｃ）必要に応じて前記分離した水処理用触媒を再生し、工程（ａ）に戻す工程
からなる硝酸性窒素含有水処理方法が開示されている。
また、本願出願人は特開２００４−５７９５４号公報（特許文献２）として、Ａｕ、Ａｇ、Ｐｔ、Ｐｄ、Ｒｈ、Ｃｕ、Ｆｅ、Ｎｉ、Ｃｏ、Ｓｎ、Ｉｎ、Ｔｉ、Ａｌ、Ｔａ、Ｓｂ、Ｒｕから選ばれる１種または２種以上の金属からなる金属微粒子であって、平均粒子径が１〜２００ｎｍの範囲にある硝酸性窒素含有水処理用触媒を開示している。
For example, in Japanese Patent Application Laid-Open No. 2004-97893 (Patent Document 1) according to the present applicant, Pt, Au, Ag, Pd, Ru, Cu, Ni, W, V are added to the inorganic oxide support and / or the carbon support. A nitrate nitrogen-containing water treatment catalyst having an average particle diameter in the range of 5 nm to 20 μm, on which one or more metal fine particles and / or alloy fine particles selected from Mo, Fe, are supported is described. In addition, as a method for treating nitrate nitrogen-containing water,
(A) a step of bringing the water treatment catalyst and nitrate nitrogen-containing water into contact with each other in the presence of a reducing agent (b) a step of separating the water treatment catalyst from the contacted nitrate nitrogen-containing water (c) ) A nitrate nitrogen-containing water treatment method comprising a step of regenerating the separated water treatment catalyst as necessary and returning to the step (a) is disclosed.
In addition, the applicant of the present application disclosed in Japanese Patent Application Laid-Open No. 2004-57954 (Patent Document 2), Au, Ag, Pt, Pd, Rh, Cu, Fe, Ni, Co, Sn, In, Ti, Al, Ta, Sb, A nitrate nitrogen-containing water treatment catalyst is disclosed which is a metal fine particle composed of one or more metals selected from Ru and having an average particle diameter in the range of 1 to 200 nm.
特開２００１−８６６号公報（特許文献３）には、原水中の硝酸性窒素および亜硝酸性窒素を、触媒を用いて水素で還元分解するにあたり、金属パラジウムと、元素比がＣｕ≧Ｐｄである銅−パラジウム合金との混合物を触媒とする水処理方法が記載されている。
特開平８−１９２１６９号公報（特許文献４）には、硝酸性窒素とアンモニア性窒素を含む排水中の硝酸性窒素を、水中で水素を発生する金属と接触させることにより、亜硝酸性窒素または窒素ガスまで還元し、溶出した金属を軟化処理によって除去した後、生成した亜硝酸性窒素およびアンモニア性窒素を触媒存在下で反応させ、窒素に転換する硝酸性窒素およびアンモニア性窒素を含む排水の処理方法が記載されている。
In Japanese Patent Laid-Open No. 2001-866 (Patent Document 3), when reducing and decomposing nitrate nitrogen and nitrite nitrogen in raw water with hydrogen using a catalyst, the elemental ratio is Cu ≧ Pd. A water treatment method using a mixture with a certain copper-palladium alloy as a catalyst is described.
In JP-A-8-192169 (Patent Document 4), nitrate nitrogen in waste water containing nitrate nitrogen and ammonia nitrogen is brought into contact with a metal that generates hydrogen in water, thereby producing nitrite nitrogen or After reducing to nitrogen gas and removing the eluted metal by softening treatment, the generated nitrite nitrogen and ammonia nitrogen are reacted in the presence of a catalyst to convert the waste water containing nitrate nitrogen and ammonia nitrogen into nitrogen. A processing method is described.
このような状況下、さらに高活性な硝酸性窒素含有水処理用触媒の開発とともに、効率的なプロセスの開発が望まれている。
本発明の目的は、低濃度の硝酸性窒素を含む飲料水の原水や、高濃度の硝酸性窒素を含む工業排水など大量の硝酸性窒素含有水から硝酸性窒素を除去する硝酸性窒素含有水の処理方法において、硝酸性窒素の還元速度を高めると共に還元ガスの利用率を向上させることのできる硝酸性窒素含有水の処理方法を提供することにある。 An object of the present invention is to remove nitrate nitrogen from a large amount of nitrate nitrogen-containing water such as raw water of drinking water containing low-concentration nitrate nitrogen or industrial wastewater containing high-concentration nitrate nitrogen. It is an object of the present invention to provide a method for treating nitrate-containing water that can increase the reduction rate of nitrate nitrogen and improve the utilization rate of reducing gas.
本発明に係る硝酸性窒素含有水の処理方法は、硝酸性窒素含有水と硝酸性窒素含有水処理用触媒とを超微細気泡還元ガスの存在下で接触させることを特徴としている。
前記超微細気泡還元ガスの大きさが平均値で０．１ｍｍ以下であることが好ましく、前記還元ガスが水素ガスであることが好ましい。
前記還元ガスの利用率が３０〜１００％の範囲にあることが好ましい。
The method for treating nitrate-nitrogen-containing water according to the present invention is characterized in that nitrate-nitrogen-containing water and a catalyst for treating nitrate-nitrogen-containing water are brought into contact in the presence of ultrafine bubble reducing gas.
The size of the ultrafine bubble reducing gas is preferably 0.1 mm or less on average, and the reducing gas is preferably hydrogen gas.
The utilization rate of the reducing gas is preferably in the range of 30 to 100%.
前記硝酸性窒素含有水処理用触媒が金属微粒子または該金属微粒子が無機酸化物担体および／またはカーボン担体に担持された粒子であり、金属微粒子の平均粒子径が１〜２００ｎｍの範囲にあり、担体の平均粒子径が５ｎｍ〜５００μｍの範囲にあることが好ましい。
前記金属がＰt、Ａu、Ａg、Ｐd、Ｒu、Ｃu、Ｎi、Ｗ、Ｖ、Ｍo、Ｆe から選ばれる１種または２種以上の金属または合金であることが好ましい。
前記無機酸化物担体がＳiＯ2、Ａl2Ｏ3、ＴiＯ2、ＺrＯ2、ＳnＯ2、Ｉn2Ｏ3、ＺnＯから選ばれる１種または２種以上の酸化物または複合酸化物であることが好ましい。
The nitrate nitrogen-containing water treatment catalyst is metal fine particles or particles in which the metal fine particles are supported on an inorganic oxide carrier and / or a carbon carrier, and the average particle diameter of the metal fine particles is in the range of 1 to 200 nm. It is preferable that the average particle diameter is in the range of 5 nm to 500 μm.
The metal is preferably one or more metals or alloys selected from Pt, Au, Ag, Pd, Ru, Cu, Ni, W, V, Mo, and Fe.
The inorganic oxide support is preferably one or more oxides or composite oxides selected from SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , In 2 O 3 , and ZnO. .
本発明に係る硝酸性窒素含有水の処理方法は、難溶性の還元ガスを超微細気泡（マイクロバブル）とし、この超微細気泡還元ガスの存在下で硝酸性窒素含有水と硝酸性窒素含有水処理用触媒とを接触させるので、硝酸性窒素の還元速度および還元ガスの利用率を大幅に向上させることができる。 In the method for treating nitrate nitrogen-containing water according to the present invention, a hardly soluble reducing gas is made into ultrafine bubbles (microbubbles), and nitrate nitrogen-containing water and nitrate nitrogen-containing water are present in the presence of the ultrafine bubble reducing gas. Since the catalyst is brought into contact with the treatment catalyst, the reduction rate of nitrate nitrogen and the utilization rate of the reducing gas can be greatly improved.
以下、本発明の硝酸性窒素含有水の処理方法について具体的に説明する。
硝酸性窒素含有水
本発明に用いる硝酸性窒素含有水としては、水中の硝酸性窒素化合物の濃度がＮとして５０〜１０，０００ｐｐｍ、さらには、１００〜５０００ｐｐｍの範囲にあることが好ましい。ここで、硝酸性窒素化合物とはＮＯ3、ＮＯ2、ＮＯ、Ｎ2Ｏを含む化合物の総称である。
処理水中の硝酸性窒素化合物の濃度がＮとして５０ｐｐｍ未満の場合は、還元分解処理することは可能であるが経済性が問題となることがある。濃度がＮとして１０，０００ｐｐｍを越えると、やはり、還元分解処理することは可能であるが還元剤（還元ガス）の使用量が多くなり経済性が問題となることがある。
このため、本発明の方法は他の吸着法、イオン交換法、逆浸透膜法、電気透析法、あるいは生物脱窒法等と併用することが好ましい場合がある。
Hereinafter, the method for treating nitrate nitrogen-containing water of the present invention will be described in detail.
The nitrate nitrogen-containing water to be used for nitrate nitrogen-containing water present invention, 50～10,000Ppm as the concentration of nitrate nitrogen compound in water is N, further preferably in the range of 100 to 5000 ppm. Here, the nitrate nitrogen compound is a general term for compounds containing NO 3 , NO 2 , NO, and N 2 O.
When the concentration of the nitrate nitrogen compound in the treated water is less than 50 ppm as N, reductive decomposition treatment is possible, but economic efficiency may be a problem. If the concentration exceeds 10,000 ppm as N, it is still possible to carry out reductive decomposition treatment, but the amount of reducing agent (reducing gas) used increases, which may cause a problem of economy.
For this reason, the method of the present invention may be preferably used in combination with other adsorption methods, ion exchange methods, reverse osmosis membrane methods, electrodialysis methods, biological denitrification methods, and the like.
硝酸性窒素含有水処理用触媒
つぎに、本発明に用いる硝酸性窒素含有水処理用触媒としては、還元剤の存在下水中の硝酸性窒素を還元分解することができれば特に制限はなく従来公知の触媒を用いることができる。
本発明では、金属微粒子または該金属微粒子が無機酸化物担体および／またはカーボン担体に担持された粒子からなる触媒を用いるのが好ましい。
金属微粒子の平均粒子径は１〜２００ｎｍ、さらには２〜１００ｎｍの範囲にあることが好ましい。金属微粒子の平均粒子径が１ｎｍ未満の場合は、これを単独で用いる場合に分散安定性が不充分であったり、処理水との分離が困難となり触媒が散逸しやすく、後述する担体に担持して用いる場合は、初期性能はよいものの経時的に凝集する傾向があり、長期にわたって初期性能を維持することが困難である。金属微粒子の平均粒子径が２００ｎｍを越えると、還元剤の吸着量が低下するとともに還元剤の活性化能も低下し、硝酸性窒素の還元分解活性が低下する。
Catalyst nitrate nitrogen-containing water treatment then, as the nitrate nitrogen-containing water treatment catalyst used in the present invention, known prior not if it is possible to reduce degradation of the nitrate nitrogen in the presence sewage reducing agent particularly limited A catalyst can be used.
In the present invention, it is preferable to use a catalyst comprising metal fine particles or particles in which the metal fine particles are supported on an inorganic oxide carrier and / or a carbon carrier.
The average particle diameter of the metal fine particles is preferably in the range of 1 to 200 nm, more preferably 2 to 100 nm. When the average particle size of the metal fine particles is less than 1 nm, when used alone, the dispersion stability is insufficient, the separation from the treated water becomes difficult and the catalyst is easily dissipated, and the catalyst is supported on the carrier described later. When used, the initial performance is good but tends to aggregate over time, and it is difficult to maintain the initial performance over a long period of time. When the average particle diameter of the metal fine particles exceeds 200 nm, the amount of reducing agent adsorbed decreases, the reducing agent activation ability also decreases, and the reductive decomposition activity of nitrate nitrogen decreases.
このような金属微粒子に用いる金属としては、Ｐt、Ａu、Ａg、Ｐd、Ｒu、Ｃu、Ｎi、Ｗ、Ｖ、Ｍo、Ｆe から選ばれる１種または２種以上の金属または合金が好適に用いられる。なかでもＣuとＰdおよび／またはＰtからなる合金微粒子は、還元剤である水素の吸着能が高くかつ常温で硝酸性窒素をＮ2とＨ2Ｏに選択的に還元分解することができる。
好ましい２成分以上の組み合わせとしては、Ｐd-Ｃu、Ｐd-Ａu、Ｐd-Ｗ、Ｐd-Ｖ、Ｐd-Ｍo、Ｐd-Ｆe、Ｐd-Ｃu／Ｐd、Ｐd-Ｃu-Ｒu、Ｐd-Ｃu-Ｆe、Ｐd-Ｃu-Ａu、Ｐt-Ｃu、Ｐt-Ａu、Ｐt-Ｗ、Ｐt-Ｖ、Ｐt-Ｍo、Ｐt-Ｆe、Ｐt-Ｃu／Ｐd、Ｐt-Ｃu-Ｒu、Ｐt-Ｃu-Ｆe、Ｐt-Ｃu-Ａu等が挙げられる。
As the metal used for such fine metal particles, one or more metals or alloys selected from Pt, Au, Ag, Pd, Ru, Cu, Ni, W, V, Mo, and Fe are preferably used. . Among them, the alloy fine particles composed of Cu and Pd and / or Pt have high adsorption ability of hydrogen as a reducing agent and can selectively reduce and decompose nitrate nitrogen to N 2 and H 2 O at room temperature.
Preferred combinations of two or more components include Pd-Cu, Pd-Au, Pd-W, Pd-V, Pd-Mo, Pd-Fe, Pd-Cu / Pd, Pd-Cu-Ru, Pd-Cu-Fe , Pd-Cu-Au, Pt-Cu, Pt-Au, Pt-W, Pt-V, Pt-Mo, Pt-Fe, Pt-Cu / Pd, Pt-Cu-Ru, Pt-Cu-Fe, Pt -Cu-Au and the like.
なお、ここで合金とは、２種以上の金属成分が均一に混合している必要はなく、単に混合物である場合も含んで意味している。また、結晶性であっても非晶質であってもよい。
このような金属微粒子は、硝酸性窒素を還元して分解する活性が高く、且つ活性劣化が小さく、また再生によって容易に活性が復元し、長期にわたって活性を維持することができる。
Here, the alloy does not need to be a mixture of two or more kinds of metal components uniformly, and includes a case where it is merely a mixture. Further, it may be crystalline or amorphous.
Such metal fine particles have a high activity for reducing and decomposing nitrate nitrogen, have a small activity deterioration, can be easily restored by regeneration, and can maintain the activity over a long period of time.
前記金属微粒子を無機酸化物担体および／またはカーボン担体に担持して用いることもできる。
無機酸化物担体としてはＳiＯ2、Ａl2Ｏ3、ＴiＯ2、ＺrＯ2、ＳnＯ2、Ｉn2Ｏ3、ＺnＯから選ばれる１種または２種以上の酸化物または複合酸化物が好適に用いられる。複合酸化物としてはＳiＯ2-Ａl2Ｏ3、ＳiＯ2-ＴiＯ2、ＳiＯ2-ＺrＯ2、ＴiＯ2-ＺrＯ2 、ＳiＯ2-Ａl2Ｏ3-ＺrＯ2などが挙げられる。これらは無定型であっても、結晶性であってもよく、結晶性の複合酸化物としては結晶性アルミノシリケート（ゼオライト）などが挙げられる。
このような無機酸化物あるいは複合酸化物は熱的にも化学的にも安定であり、さらに微細な触媒粒子の調製が容易である。
一方、カーボン担体を用いると、得られる触媒粒子の比表面積が高く、金属微粒子が高分散しているので硝酸性窒素の還元分解活性に優れている。
The metal fine particles may be used by being supported on an inorganic oxide carrier and / or a carbon carrier.
As the inorganic oxide carrier, one or more oxides or composite oxides selected from SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , In 2 O 3 and ZnO are preferably used. . Examples of the composite oxide include SiO 2 —Al 2 O 3 , SiO 2 —TiO 2 , SiO 2 —ZrO 2 , TiO 2 —ZrO 2 , and SiO 2 —Al 2 O 3 —ZrO 2 . These may be amorphous or crystalline, and crystalline composite oxides include crystalline aluminosilicate (zeolite).
Such an inorganic oxide or composite oxide is thermally and chemically stable, and it is easy to prepare fine catalyst particles.
On the other hand, when a carbon support is used, the specific surface area of the obtained catalyst particles is high, and the metal fine particles are highly dispersed, so that the reductive decomposition activity of nitrate nitrogen is excellent.
無機酸化物担体および／またはカーボン担体の平均粒子径は５ｎｍ〜５００μｍ、さらには４０ｎｍ〜１００μｍの範囲にあることが好ましい。担体の平均粒子径が前記範囲にあれば、前記金属微粒子を担持して得られる触媒の平均粒子径も概ね５ｎｍ〜５００μｍの範囲にあり、水に分散した際に、容易に凝集したり沈降することなく安定して分散する。また、触媒粒子の外部表面積が大きいので粒子径の大きな粒子や成形体に比して高い活性を発現し、硝酸性窒素の還元分解に好適である。 The average particle diameter of the inorganic oxide support and / or the carbon support is preferably in the range of 5 nm to 500 μm, more preferably 40 nm to 100 μm. If the average particle size of the carrier is in the above range, the average particle size of the catalyst obtained by supporting the metal fine particles is also in the range of about 5 nm to 500 μm, and easily aggregates or settles when dispersed in water. Disperses stably without any problems. Further, since the external surface area of the catalyst particles is large, the catalyst particles exhibit high activity as compared with particles having a large particle diameter or molded articles, and are suitable for reductive decomposition of nitrate nitrogen.
前記担体の平均粒子径が５ｎｍ未満の場合は、他の不純物等を吸着することにより、凝集することがあり、硝酸性窒素あるいは還元剤との接触効率が低下するために処理能力が低下する。また、必要に応じて処理液と触媒成分との分離を行う場合に分離が困難となる。
また、担体の平均粒子径が５００μｍを越えると、得られる触媒粒子が大きいために沈降することがあり、また硝酸性窒素あるいは還元剤との接触効率が低下して充分な還元分解活性が得られないことがある。さらに、触媒粒子が沈降すると長期連続運転が困難となることがあり、停止してメンテナンスが必要となる。
When the average particle size of the carrier is less than 5 nm, it may aggregate by adsorbing other impurities and the like, and the contact efficiency with nitrate nitrogen or a reducing agent is lowered, so that the treatment capacity is lowered. In addition, separation is difficult when the treatment liquid and the catalyst component are separated as necessary.
On the other hand, if the average particle diameter of the carrier exceeds 500 μm, the resulting catalyst particles may be large and may settle, and the contact efficiency with nitrate nitrogen or a reducing agent will be reduced, resulting in sufficient reductive decomposition activity. There may not be. Furthermore, if the catalyst particles settle, long-term continuous operation may be difficult, and maintenance is required after stopping.
つぎに、硝酸性窒素含有水処理用触媒粒子中の金属微粒子の担持量は、金属として１〜５０重量％、さらには２〜２０重量％の範囲にあることが好ましい。触媒粒子中の金属微粒子の担持量が金属として１重量％未満の場合は、還元分解活性が不充分であり、担持量が金属として５０重量％を越えると、担持することが困難であるとともに、仮に担持できてもさらに還元分解活性が向上することもないので経済性が低下する。また、金属微粒子同士が互いに合体して粒子成長することがあり、還元分解活性が低下することがある。 Next, the loading amount of the metal fine particles in the nitrate nitrogen-containing water treatment catalyst particles is preferably in the range of 1 to 50% by weight, more preferably 2 to 20% by weight as a metal. When the supported amount of the metal fine particles in the catalyst particles is less than 1% by weight as a metal, the reductive decomposition activity is insufficient, and when the supported amount exceeds 50% by weight as a metal, it is difficult to support. Even if it can be supported, the reductive decomposition activity is not further improved, so the economic efficiency is lowered. In addition, metal fine particles may coalesce with each other to grow particles, which may reduce the reductive decomposition activity.
続いて、上記硝酸性窒素含有水処理用触媒の製造方法について例示的に説明する。
（第１方法）
前記した無機酸化物微粒子および／またはカーボン微粒子の分散液を調製する。これに、所定量の１種または２種以上の金属塩水溶液を加え、無機酸化物微粒子および／またはカーボン微粒子に金属塩水溶液を吸収させ、次いで乾燥し、その後２００〜８００℃の温度で、還元ガス例えばＨ2、ＮＨ3雰囲気下で通常０．５〜６時間程度還元処理することによって硝酸性窒素含有水処理用触媒微粒子を得ることができる。
金属塩としては、硝酸パラジウム、塩化パラジウム、酢酸パラジウム、テトラアンミンパラジウム、塩化白金、硝酸銀、塩化銅、硝酸ニッケル、酢酸ルテニウムなど前記した金属の塩で水に可溶な塩を用いることができる。
乾燥方法としては、凍結乾燥、噴霧乾燥、静置乾燥、ロータリーエバポレーター等、従来公知の方法を採用することができる。
Then, the manufacturing method of the said nitrate nitrogen containing water treatment catalyst is demonstrated exemplarily.
(First method)
A dispersion of the above-described inorganic oxide fine particles and / or carbon fine particles is prepared. To this, a predetermined amount of one or more metal salt aqueous solutions are added, and the inorganic oxide fine particles and / or carbon fine particles absorb the metal salt aqueous solution, and then dried, followed by reduction at a temperature of 200 to 800 ° C. The catalyst fine particles for water treatment with nitrate nitrogen can be obtained by reduction treatment for about 0.5 to 6 hours under a gas atmosphere such as H 2 or NH 3 .
As the metal salt, water-soluble salts such as palladium nitrate, palladium chloride, palladium acetate, tetraammine palladium, platinum chloride, silver nitrate, copper chloride, nickel nitrate, and ruthenium acetate can be used.
As a drying method, conventionally known methods such as freeze drying, spray drying, stationary drying, and rotary evaporator can be employed.
上記において、還元温度が２００℃未満の時は、金属塩の還元が不充分となり、金属微粒子の生成が不充分となる。還元温度が８００℃を越えると、金属微粒子が粒子成長し過ぎたり、触媒微粒子が強く凝集して、分散性が低下し、限外濾過等により分離できない場合があり、粒子径の小さな触媒粒子を用いた硝酸性窒素を含む水の安定的な処理が困難となる。好ましい還元温度は２５０〜６００℃の範囲である。
本発明の触媒粒子における金属微粒子の粒子径の測定方法は、ＦＥ-ＴＥＭ（ＳＴＥＭ-ＨＡＡＤＦ法）により測定することができる。
In the above, when the reduction temperature is less than 200 ° C., the reduction of the metal salt is insufficient and the generation of metal fine particles is insufficient. When the reduction temperature exceeds 800 ° C., the metal fine particles grow too much, or the catalyst fine particles are strongly aggregated, the dispersibility is lowered, and may not be separated by ultrafiltration or the like. Stable treatment of water containing nitrate nitrogen used becomes difficult. A preferable reduction temperature is in the range of 250 to 600 ° C.
The method for measuring the particle diameter of the metal fine particles in the catalyst particles of the present invention can be measured by FE-TEM (STEM-HAADF method).
（第２方法）
ゼオライトの分散液、必要に応じて予め前記金属イオン以外のアンモニウムイオン等でイオン交換したゼオライトの分散液を調製する。これに、所定量の１種または２種以上の金属塩水溶液を加えイオン交換し、次いでゼオライト粒子を濾過分離し、第１方法と同様にして乾燥し、ついで還元処理することによって硝酸性窒素含有水処理用触媒粒子を得ることができる。
(Second method)
A zeolite dispersion is prepared, and if necessary, a zeolite dispersion that has been previously ion-exchanged with ammonium ions other than the metal ions is prepared. To this, a predetermined amount of one or two or more metal salt aqueous solutions are added and ion exchanged, and then the zeolite particles are separated by filtration, dried in the same manner as in the first method, and then reduced to contain nitrate nitrogen. Catalyst particles for water treatment can be obtained.
（第３方法）
前記した無機酸化物粒子および／またはカーボン粒子の分散液を調製する。これに、所定量の１種または２種以上の金属塩水溶液を加え、ついで水素化硼素ナトリウム（ＮａＢＨ4）、次亜リン酸ソーダ、ヒドラジン等の還元剤を加え、無機酸化物粒子および／またはカーボン粒子上に金属を析出させる。ついで、必要に応じて１００〜３００℃にてオートクレーブ処理することにより、溶液中に析出した金属微粒子を担体粒子上に析出させることができる。
続いて、濾過分離し、第１方法と同様にして乾燥し、ついで加熱処理（好ましくは還元雰囲気下で加熱処理）することによって硝酸性窒素含有水処理用触媒粒子を得ることができる。
(Third method)
A dispersion of the inorganic oxide particles and / or carbon particles described above is prepared. To this, a predetermined amount of one or more metal salt aqueous solutions are added, and then a reducing agent such as sodium borohydride (NaBH 4 ), sodium hypophosphite, hydrazine is added, and inorganic oxide particles and / or Metal is deposited on the carbon particles. Then, if necessary, by performing autoclaving at 100 to 300 ° C., the metal fine particles deposited in the solution can be deposited on the carrier particles.
Subsequently, the catalyst particles for nitrate-containing water treatment can be obtained by filtration and separation, drying in the same manner as in the first method, and then heat treatment (preferably heat treatment in a reducing atmosphere).
（第４方法）
硝酸パラジウムと硝酸銅との混合水溶液に、クエン酸水溶液に還元剤として硫酸第一鉄を溶解した溶液を添加してＰd-Ｃu合金微粒子分散液を調製した。このＰd-Ｃu合金微粒子分散液に無機酸化物粒子分散液を混合してＰd-Ｃu合金微粒子を無機酸化物担体に担持した触媒粒子を調製した。
ついで、濾過分離し、第１方法と同様にして乾燥し、ついで加熱処理（好ましくは不活性ガスまたは還元ガス雰囲気下で加熱処理）することによって硝酸性窒素含有水処理用触媒微粒子を得ることができる。
(4th method)
A solution of ferrous sulfate dissolved as a reducing agent in an aqueous citric acid solution was added to a mixed aqueous solution of palladium nitrate and copper nitrate to prepare a Pd—Cu alloy fine particle dispersion. The Pd—Cu alloy fine particle dispersion was mixed with an inorganic oxide particle dispersion to prepare catalyst particles having Pd—Cu alloy fine particles supported on an inorganic oxide carrier.
Next, the catalyst fine particles for nitrate nitrogen-containing water treatment can be obtained by filtration and separation, drying in the same manner as in the first method, and then heat treatment (preferably heat treatment in an inert gas or reducing gas atmosphere). it can.
上記のようにして得られる硝酸性窒素含有水処理用触媒粒子は、平均粒子径が概ね５ｎｍ〜５００μｍ、さらには４０ｎｍ〜１００μｍの範囲にあることが好ましい。
また、触媒微粒子中の金属微粒子の含有量は１〜５０重量％、さらには２〜２０重量％の範囲にあることが好ましい。
The nitrate nitrogen-containing water treatment catalyst particles obtained as described above preferably have an average particle diameter in the range of about 5 nm to 500 μm, more preferably 40 nm to 100 μm.
Further, the content of the metal fine particles in the catalyst fine particles is preferably in the range of 1 to 50% by weight, more preferably 2 to 20% by weight.
超微細気泡還元ガス
本発明に用いる還元ガスとしては、電気分解で容易に製造することができ、必要に応じて回収することができる等の点から水素ガスが好適に採用される。
超微細気泡還元ガスは、大きさが平均値で０．１ｍｍ以下、概ね０．０５〜１００μｍ、さらには５０μｍ以下、特に３０μｍ以下であることが好ましい。超微細気泡還元ガスの大きさが０．１ｍｍを超えると還元ガスの硝酸性窒素含有水への溶解速度が遅くなるためか、硝酸性窒素の還元速度（処理速度）が遅くなるとともに還元ガスの利用率が低下し、処理効率が低下するとともに経済性が低下する。ここで、還元ガスの利用率とは供給した還元ガスの内、硝酸性窒素の還元に用いられた還元ガスの割合をいう。
また、超微細気泡還元ガスの大きさが平均値で０．０５μｍ未満のものは現在のところ得ることが困難である。
Ultrafine bubble reducing gas As the reducing gas used in the present invention, hydrogen gas is preferably employed from the viewpoint that it can be easily produced by electrolysis and can be recovered as required.
The ultrafine bubble reducing gas has an average value of 0.1 mm or less, generally 0.05 to 100 μm, more preferably 50 μm or less, and particularly preferably 30 μm or less. If the size of the ultrafine bubble reducing gas exceeds 0.1 mm, the rate of dissolution of the reducing gas in the nitrate nitrogen-containing water slows, or the rate of reduction of nitrate nitrogen (treatment rate) slows and the reducing gas The utilization rate decreases, the processing efficiency decreases, and the economic efficiency decreases. Here, the utilization rate of the reducing gas refers to the ratio of the reducing gas used for reducing nitrate nitrogen in the supplied reducing gas.
Also, it is difficult to obtain an ultrafine bubble reducing gas having an average value of less than 0.05 μm on average.
このような水中における気泡の大きさの測定方法は、例えば、水中パーティクルカウンター（リオン（株）製：ＫＲ−３２またはＫＲ−６０）等によって測定することができる。
なお、本発明では前記水素ガス以外に必要に応じて、別途ヒドラジン、水素化硼素ナトリウム、次亜リン酸ナトリウム、キノン、ヒドロキノン等の還元剤を硝酸性窒素含有水に添加して用いることもできる。
本発明の硝酸性窒素含有水の処理方法に用いる処理設備の方式には特に制限はなく、前記した超微細気泡還元ガスを発生させ供給できる設備を備えていれば従来公知の方式を採用することができ、例えば、完全混合槽型や、流通型、多段型、バッチ型等の種々の方式がある。これらは、通常の撹拌装置、循環装置等を備えている。
Such a method for measuring the size of bubbles in water can be measured by, for example, an underwater particle counter (manufactured by Lion Co., Ltd .: KR-32 or KR-60).
In the present invention, a reducing agent such as hydrazine, sodium borohydride, sodium hypophosphite, quinone, hydroquinone and the like can be separately added to the nitrate nitrogen-containing water as necessary in addition to the hydrogen gas. .
There is no particular limitation on the method of treatment equipment used in the method for treating nitrate nitrogen-containing water of the present invention, and a conventionally known method should be adopted as long as it has equipment capable of generating and supplying the ultrafine bubble reducing gas described above. For example, there are various methods such as a complete mixing tank type, a distribution type, a multistage type, and a batch type. These are equipped with a normal stirring device, a circulation device and the like.
超微細気泡還元ガス発生・供給装置としては前記した大きさの気泡を供給できれば特に制限はなく、例えば(1)多孔質板に圧力をかけて微細気泡を発生させる方法、(2)微小径ノズルから気体を噴出し微細気泡を発生させる方法、(3)単管の壁面に突起を設けて気体を衝突させて微細気泡を発生させる方法、(4)気体、液体の噴流間の不安定性を利用する方法、(5)流体で旋回流を作り、気体と共に放出させて微細気泡を発生させる方法などがある。
中でも(1)または(2)の方法は好適である。具体的には、例えば、スキルキット（株）製のマイクロバブル発生装置、資源開発（株）製のＡＷＡＷＡなどが好適に使用できる。
The ultrafine bubble reducing gas generating / supplying device is not particularly limited as long as it can supply bubbles of the above-described size. For example, (1) a method of generating fine bubbles by applying pressure to a porous plate, (2) a fine diameter nozzle A method of generating fine bubbles by ejecting gas from a gas, (3) A method of generating protrusions on the wall of a single tube and causing gas to collide, and (4) Instability between gas and liquid jets And (5) creating a swirl flow with a fluid and releasing it with a gas to generate fine bubbles.
Of these, the method (1) or (2) is preferred. Specifically, for example, Skillkit Co., Ltd. microbubble generator, Resource Development Co., Ltd. AWAWA etc. can be used conveniently.
硝酸性窒素含有水中の硝酸性窒素含有水処理用触媒の濃度は０．０５〜２０重量％、さらには０．１〜１０重量％の範囲にあることが好ましい。触媒濃度が０．０５重量％未満の場合は、処理温度が常温以下の場合に還元分解速度が不充分で、硝酸性窒素を所望の濃度以下に低減することが困難となる。触媒濃度が２０重量％を超えると、濃度が高過ぎて処理還元ガスの分散性が低下して処理効率が低下したり、触媒の使用量が多過ぎて経済性が問題となることがある。 The concentration of the nitrate nitrogen-containing water treatment catalyst in the nitrate nitrogen-containing water is preferably 0.05 to 20% by weight, more preferably 0.1 to 10% by weight. When the catalyst concentration is less than 0.05% by weight, the reductive decomposition rate is insufficient when the treatment temperature is room temperature or lower, and it is difficult to reduce nitrate nitrogen below the desired concentration. If the catalyst concentration exceeds 20% by weight, the concentration may be too high and the dispersibility of the treatment reducing gas may be lowered to lower the treatment efficiency, or the amount of catalyst used may be too high, resulting in a problem of economy.
本発明の処理方法において、硝酸性窒素含有水と水処理用触媒との接触時間（滞留時間）は、処理を必要とする水の量および水中の硝酸性窒素の濃度、要求される処理水（清浄水）中のＮ濃度レベル、処理温度、触媒中の金属微粒子の量、粒子径、処理水のｐＨや不純物の他処理方法・装置等によって異なるが、概ね１００時間以下、通常１０分間〜２５時間の範囲にあることが好ましい。 In the treatment method of the present invention, the contact time (retention time) between the nitrate nitrogen-containing water and the water treatment catalyst is the amount of water that requires treatment, the concentration of nitrate nitrogen in the water, the required treated water ( N concentration level in clean water), treatment temperature, amount of metal fine particles in catalyst, particle diameter, pH of treated water and other treatment methods / devices of impurities, etc., but generally 100 hours or less, usually 10 minutes to 25 It is preferably in the time range.
また、還元剤（還元ガス）の供給量は、要求される処理後の残存窒素濃度によっても異なるが、下記化学反応式（１）に示されるように、概ね水硝酸性窒素と還元剤との量論量以上であればよく、例えば硝酸性窒素がＮＯ3の場合、本発明の処理方法では、還元剤のモル数（ＭR）と硝酸性窒素（ＮＯ3）のモル数（ＭN）と比（ＭR／ＭN）が３〜１５、さらには３〜６の範囲にあることが好ましい。
２ＮＯ3 ＋ ６Ｈ2 → Ｎ2 ＋ ６Ｈ2Ｏ ・・・（１）
前記モル比が３未満の場合は還元剤が少ないために、得られる処理後の水（清浄水）中の硝酸性窒素濃度が高く、所期の目的を達成できないことがあり、モル比が１５を越えると、ＮＨ3の生成が増加したり還元剤の利用率が低下し、さらに、還元剤を回収する場合でも回収量が多くなり経済性が低下する。
In addition, although the supply amount of the reducing agent (reducing gas) varies depending on the required residual nitrogen concentration after the treatment, as shown in the following chemical reaction formula (1), the amount of water nitrate nitrogen and the reducing agent is roughly For example, when nitrate nitrogen is NO 3 , in the treatment method of the present invention, the number of moles of reducing agent (M R ) and the number of moles of nitrate nitrogen (NO 3 ) (M N ). And the ratio (M R / M N ) is preferably in the range of 3 to 15, more preferably 3 to 6.
2NO 3 + 6H 2 → N 2 + 6H 2 O (1)
When the molar ratio is less than 3, since there are few reducing agents, the concentration of nitrate nitrogen in the resulting treated water (clean water) is high, and the intended purpose may not be achieved. If it exceeds 1, the production of NH 3 will increase or the utilization rate of the reducing agent will decrease, and even when the reducing agent is recovered, the recovered amount will increase and the economic efficiency will decrease.
なお、還元処理する際は、必要に応じて酸またはアルカリを添加してｐＨ調整し、ｐＨ３〜１０、さらには４〜９の範囲とすることが好ましい。
硝酸性窒素含有水のｐＨが３未満の場合は、触媒中の金属微粒子の金属が溶出し、活性が低下したり、処理水中に金属が含まれたり、酸性であるためにそのまま排水とすることができない等の問題が生じることがある。硝酸性窒素含有水のｐＨが１０を越えると、硝酸性窒素の還元速度が遅くなるとともにＮＨ3の副生が増加する傾向がある。
In addition, when carrying out a reduction process, it is preferable to add an acid or an alkali as needed, and to adjust pH to pH 3-10, Furthermore, it is preferable to be the range of 4-9.
If the pH of the nitrate nitrogen-containing water is less than 3, the metal particles in the catalyst elute and the activity decreases, the metal is contained in the treated water, or it is acidic, so it should be used as wastewater. Problems such as inability to do so may occur. When the pH of the nitrate nitrogen-containing water exceeds 10, the reduction rate of nitrate nitrogen tends to be slow and NH 3 by-product tends to increase.
本発明の硝酸性窒素含有水の処理方法では、前記還元ガスの利用率が３０〜１００％、さらには５０〜１００％の範囲にあることが好ましい。還元ガスの利用率が３０％未満の場合は、処理後の水（清浄水）中の硝酸性窒素の残存濃度が高く、所期の目的を達成できない場合や、経済性が問題となる。未利用の還元ガスは回収して再度利用することができる。 In the method for treating nitrate-nitrogen-containing water of the present invention, it is preferable that the utilization rate of the reducing gas is in the range of 30 to 100%, more preferably 50 to 100%. When the utilization rate of the reducing gas is less than 30%, the residual concentration of nitrate nitrogen in the treated water (clean water) is high, and the intended purpose cannot be achieved, or the economy becomes a problem. Unused reducing gas can be recovered and reused.
所望の濃度に処理した処理水は、処理水と触媒を分離し、触媒はそのまま繰り返し使用することができるが、必要に応じて再生して用いることもできる。
処理水と触媒とを分離する方法としては限外濾過膜、セラミックフィルター等を用いた方法を採用することができる。特に流通式セラミックフィルターは口径を触媒粒子径に応じて選択することができるので効率的に分離することができ、またフィルターの圧密化などによる口径の変化がなく、耐久性に優れているので好ましい。
The treated water treated to a desired concentration separates the treated water and the catalyst, and the catalyst can be used repeatedly as it is, but can be regenerated and used as necessary.
As a method for separating the treated water and the catalyst, a method using an ultrafiltration membrane, a ceramic filter or the like can be employed. In particular, a flow-through ceramic filter is preferable because it can be separated efficiently because the diameter can be selected according to the catalyst particle diameter, and there is no change in the diameter due to the consolidation of the filter, etc., and it is excellent in durability. .
このようにして処理された処理水中のＮ濃度（硝酸性Ｎおよび副生することのあるアンモニア性Ｎの合計）は１００ｐｐｍ以下、好ましくは１０ｐｐｍ以下であることが好ましい。
なお、下記化学反応式（２）に示されるように、硝酸性窒素含有水の処理によって副生することのあるＮＨ3ガスは、必要に応じてアンモニアストリッピング等、従来公知の方法によって除去することができる。
２ＮＯ3 ＋ ９Ｈ2 → ２ＮＨ3 ＋ ６Ｈ2Ｏ ・・・（２）
以下に実施例を示して本発明をさらに具体的に説明するが、本発明はこれにより何ら限定されるものではない。
The N concentration in the treated water thus treated (the total of nitrate N and ammoniacal N which may be by-produced) is 100 ppm or less, preferably 10 ppm or less.
In addition, as shown in the following chemical reaction formula (2), NH 3 gas that may be by-produced by the treatment of nitrate nitrogen-containing water is removed by a conventionally known method such as ammonia stripping as necessary. be able to.
2NO 3 + 9H 2 → 2NH 3 + 6H 2 O (2)
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.
触媒(1)の調製
活性炭（日本エンバイロケミカルズ (株)製：白鷺Ｐ、平均粒子径５０μｍ）８７０ｇを水１７４０ｇに分散させた水溶液に、塩化パラジウム(田中貴金属販売(株)製)１７２．４ｇと、硝酸銅３水和物(関東化学(株)製)１２８ｇを水１７４０ｇに溶解して調製した混合水溶液を添加し、ついで、濃度５．０重量％の水酸化ナトリウムを加え、分散液のｐＨを９．０にし、活性炭粒子の表面にパラジウム水酸化物、銅水酸化物の沈殿を析出させた。ついで、これを濾過洗浄し、６０℃で２４時間乾燥した。
Preparation of catalyst (1) 172.4 g of palladium chloride (manufactured by Tanaka Kikinzoku Co., Ltd.) in an aqueous solution in which 870 g of activated carbon (manufactured by Nippon Enviro Chemicals Co., Ltd .: Shirasagi P, average particle size 50 μm) was dispersed in 1740 g of water Then, a mixed aqueous solution prepared by dissolving 128 g of copper nitrate trihydrate (manufactured by Kanto Chemical Co., Ltd.) in 1740 g of water was added, and then sodium hydroxide having a concentration of 5.0% by weight was added to the pH of the dispersion. Was set to 9.0, and precipitates of palladium hydroxide and copper hydroxide were deposited on the surface of the activated carbon particles. Then, this was washed by filtration and dried at 60 ° C. for 24 hours.
この乾燥物を粉体還元焼成炉（入江製作所(株)製）に充填し、還元処理用ガス（水素５容量％、窒素９５容量％）を５Ｌ／ｍｉｎの量で供給しながら温度１８０℃まで昇温し、この温度を２時間維持し、ついで還元処理用ガス（水素５０容量％、窒素５０容量％）を５Ｌ／ｍｉｎの量で供給しながら温度５００℃まで昇温し、この温度を６時間維持し、ついで、室温に冷却することによって還元処理した触媒(1)を調製した。
触媒(1)のＰd含有量は１０重量％、Ｃu含有量は３．３重量％であった。金属微粒子（合金）の平均粒子径は１２ｎｍであった。
The dried product is filled in a powder reduction firing furnace (Irie Seisakusho Co., Ltd.), and a reduction gas (5% by volume of hydrogen, 95% by volume of nitrogen) is supplied at a rate of 5 L / min up to a temperature of 180 ° C. The temperature was raised and maintained at this temperature for 2 hours, and then the temperature was raised to 500 ° C. while supplying a reducing gas (50% by volume of hydrogen and 50% by volume of nitrogen) at a rate of 5 L / min. A reduction catalyst (1) was prepared by maintaining for a time and then cooling to room temperature.
The catalyst (1) had a Pd content of 10% by weight and a Cu content of 3.3% by weight. The average particle size of the metal fine particles (alloy) was 12 nm.
硝酸性窒素含有水の処理
硝酸ナトリウム(関東化学(株)製：特級)６１.３ｇを純水に溶解して硝酸性窒素含有水２５ｋｇを調製した。このときの硝酸性窒素の含有量はＮとして４００ｐｐｍであった。
次に、超微細気泡還元ガス発生装置（スキルキット（株）製：マイクロバブル発生装置）の水槽に硝酸性窒素含有水を投入し、硝酸性窒素含有水を循環させながらこれに触媒(1)１０００ｇを分散させた。このときの硝酸性窒素含有水中の触媒(1)の分散濃度は３．８重量％である。
ついで水素ガスの超微細気泡を吹き込み、硝酸性窒素含有水の処理を実施した。この時、液温を２５℃に維持し、水槽は２００ｒｐｍで攪拌した。マイクロバブル発生装置は、液循環量７０Ｌ／ｍｉｎ、液圧力０.４５ＭＰa、水素圧力０.４５ＭＰa とし、水素の流量を０.３７ＮＬ／ｍｉｎの条件で注入し、硝酸性窒素の処理中は、硝酸性窒素含有水のｐＨを濃度１重量％の硫酸にて５〜６の範囲に調整した。このときに発生した水素の超微細気泡（マイクロバブル）の大きさは、パーティクルカウンター（リオン（株）製：ＫＲ−３２）により測定したところ、４〜２０μｍ（平均値：１０μｍ）であった。
Treatment of nitrate nitrogen-containing water 61.3 g of sodium nitrate (manufactured by Kanto Chemical Co., Ltd .: special grade) was dissolved in pure water to prepare 25 kg of nitrate nitrogen-containing water. At this time, the content of nitrate nitrogen was 400 ppm as N.
Next, nitrate nitrogen-containing water is put into the water tank of the ultrafine bubble reducing gas generator (manufactured by Skillkit Co., Ltd .: Microbubble generator), and the catalyst is used while circulating the nitrate nitrogen-containing water (1) 1000 g was dispersed. At this time, the dispersion concentration of the catalyst (1) in nitrate nitrogen-containing water is 3.8% by weight.
Subsequently, ultrafine bubbles of hydrogen gas were blown in to treat the nitrate-containing water. At this time, the liquid temperature was maintained at 25 ° C., and the water tank was stirred at 200 rpm. The microbubble generator has a liquid circulation rate of 70 L / min, a liquid pressure of 0.45 MPa, a hydrogen pressure of 0.45 MPa and a hydrogen flow rate of 0.37 NL / min. The pH of the basic nitrogen-containing water was adjusted to a range of 5 to 6 with sulfuric acid having a concentration of 1% by weight. The size of ultrafine bubbles (microbubbles) of hydrogen generated at this time was 4 to 20 μm (average value: 10 μm) as measured by a particle counter (manufactured by Rion Co., Ltd .: KR-32).
水素の超微細気泡を供給開始後５分毎に処理液を採取し、窒素分析装置（ブランルーベ（株）製：ＡＡＳ−III）により硝酸性窒素（ＮＯ3＋ＮＯ2）およびＮＨ3の分析を行った。
硝酸性窒素の還元は１３０分（ＮＯ3＋ＮＯ2が０ｐｐｍとなった時点）で終了し、このときの副生ＮＨ3濃度、水素の供給量、およびＮ2生成のための水素利用率、ＮＨ3副生のための水素利用率、水素未利用率を表１に示した。
A processing solution is collected every 5 minutes after the start of supplying ultrafine hydrogen bubbles, and nitrate nitrogen (NO 3 + NO 2 ) and NH 3 are analyzed using a nitrogen analyzer (Blanlube Co., Ltd .: AAS-III). It was.
The reduction of nitrate nitrogen was completed in 130 minutes (when NO 3 + NO 2 became 0 ppm), and the concentration of by-product NH 3 , the amount of hydrogen supplied, and the hydrogen utilization rate for N 2 production, NH 3 hydrogen utilization rate for by-product, hydrogen unutilized ratio shown in Table 1.
硝酸性窒素含有水の処理
実施例１において、水素の流量を０.４８ＮＬ／ｍｉｎで実施した以外は、同様の条件で硝酸性窒素含有水の処理を実施した。処理結果を表１に示す。
Treatment of nitrate nitrogen-containing water In Example 1, the nitrate nitrogen-containing water was treated under the same conditions except that the flow rate of hydrogen was 0.48 NL / min. The processing results are shown in Table 1.
硝酸性窒素含有水の処理
実施例１において、水素の流量を０.６３ＮＬ／ｍｉｎで実施した以外は、同様の条件で硝酸性窒素含有水の処理を実施した。処理結果を表１に示す。
Treatment of nitrate nitrogen-containing water In Example 1, the nitrate nitrogen-containing water was treated under the same conditions except that the flow rate of hydrogen was 0.63 NL / min. The processing results are shown in Table 1.
硝酸性窒素含有水の処理
実施例１において、水素の流量を０.９３ＮＬ／ｍｉｎで実施した以外は、同様の条件で硝酸性窒素含有水の処理を実施した。処理結果を表１に示す。
Treatment of nitrate nitrogen-containing water In Example 1, the nitrate nitrogen-containing water was treated under the same conditions except that the flow rate of hydrogen was 0.93 NL / min. The processing results are shown in Table 1.
硝酸性窒素含有水の処理
実施例１において、水素の流量を１.３１ＮＬ／ｍｉｎで実施した以外は、同様の条件で硝酸性窒素含有水の処理を実施した。処理結果を表１に示す。
Treatment of nitrate nitrogen-containing water In Example 1, the nitrate nitrogen-containing water was treated under the same conditions except that the flow rate of hydrogen was 1.31 NL / min. The processing results are shown in Table 1.
触媒(2)の調製
実施例１において、３６５．０ｇの塩化パラジウム(田中貴金属販売(株)製)と、４１３．５ｇの硝酸銅３水和物(関東化学(株)製)とを用いた以外は同様にして、還元処理した触媒(2)を調製した。触媒(2)のＰd含有量は１０重量％、Ｃu含有量は５重量％であった。金属微粒子（合金）の平均粒子径は１３ｎｍであった。
硝酸性窒素含有水の処理
実施例３において、触媒(2)を用いた以外は同様の条件で硝酸性窒素含有水の処理を実施した。結果を表１に示す。
Preparation of catalyst (2) In Example 1, 365.0 g of palladium chloride (manufactured by Tanaka Kikinzoku Co., Ltd.) and 413.5 g of copper nitrate trihydrate (manufactured by Kanto Chemical Co., Ltd.) were used. A reduced catalyst (2) was prepared in the same manner except for the above. The catalyst (2) had a Pd content of 10% by weight and a Cu content of 5% by weight. The average particle diameter of the metal fine particles (alloy) was 13 nm.
Treatment of nitrate nitrogen-containing water In Example 3, the nitrate nitrogen-containing water was treated under the same conditions except that the catalyst (2) was used. The results are shown in Table 1.
触媒(3)の調製
純水１０００ｇに、予めクエン酸３ナトリウムを得られる合金微粒子１重量部当たり０.０１重量部となるように加え、これに金属換算で濃度が１０重量％となり、合金微粒子を構成する銅とパラジウムの重量比が２／１となるように硝酸銅および硝酸パラジウムを加え、さらに液中の硝酸銅および硝酸パラジウムの合計モル数と等モル数の硫酸第一鉄の水溶液を添加し、窒素雰囲気下で１時間攪拌して合金微粒子の分散液を得た。合金微粒子の平均粒子径は８ｎｍであった。
得られた分散液は遠心分離器により水洗して不純物を除去した後、水に分散させ、濃度１０重量％の合金微粒子(1)の分散液とし、これにシリカゾル（触媒化成工業（株）製：ＳＳ−３００、平均粒子径３００ｎｍ、ＳiＯ2濃度２０重量％）４５００ｇを混合し、分散液のｐＨを８に調整し、２時間撹拌した。ついで、凍結乾燥した後、Ｈ2−Ｎ2 混合ガス雰囲気下、２５０℃で２時間加熱処理し、還元処理した触媒(3)を調製した。触媒(3)のＰd含有量は１０重量％、Ｃu含有量は５重量％であった。
硝酸性窒素含有水の処理
実施例３において、触媒(3)を用いた以外は同様の条件で硝酸性窒素含有水の処理を実施した。結果を表１に示す。
Preparation of pure water 1000g of a catalyst (3) was added so as to advance 0.01 part by weight the alloy particle 1 part by weight per obtained trisodium citrate, becomes 10 wt% concentration at which the terms of the metal, alloy fine particles Copper nitrate and palladium nitrate were added so that the weight ratio of copper and palladium constituting the mixture was 2/1, and an aqueous solution of ferrous sulfate having an equivalent number of moles of copper nitrate and palladium nitrate in the liquid was added. The resulting mixture was stirred for 1 hour in a nitrogen atmosphere to obtain a dispersion of alloy fine particles. The average particle size of the alloy fine particles was 8 nm.
The obtained dispersion is washed with water by a centrifugal separator to remove impurities, and then dispersed in water to form a dispersion of alloy fine particles (1) having a concentration of 10% by weight. This is a silica sol (manufactured by Catalyst Kasei Kogyo Co., Ltd.). : SS-300, average particle diameter 300 nm, SiO 2 concentration 20 wt%) 4500 g were mixed, the pH of the dispersion was adjusted to 8, and stirred for 2 hours. Next, after lyophilization, a reduction treatment catalyst (3) was prepared by heat treatment at 250 ° C. for 2 hours in an H 2 —N 2 mixed gas atmosphere. The catalyst (3) had a Pd content of 10% by weight and a Cu content of 5% by weight.
Treatment of nitrate nitrogen-containing water In Example 3, the nitrate nitrogen-containing water was treated under the same conditions except that the catalyst (3) was used. The results are shown in Table 1.
硝酸性窒素含有水の処理
実施例１と同様の方法で被処理液を調製し、触媒(1)の分散濃度が３．８重量％となるように分散させ、ついで水槽の底部より水素を吹き込むバブリング管（内径１ｍｍ）を導入して、水素の流量０.７１ＮＬ/ｍｉｎで吹き込み、超微細気泡還元ガス発生装置を用いることなく硝酸性窒素含有水の処理を実施した。この時、液温を２５℃に維持し、水槽は２００ｒｐｍで攪拌した。硝酸性窒素の処理中は、硝酸性窒素含有水のｐＨを濃度１重量％の硫酸にて５〜６の範囲に調整した。このときに発生した水素の気泡の大きさは、１ｍｍ以上であった。結果を表１に示す。
Treatment of nitrate nitrogen-containing water Prepare a liquid to be treated in the same manner as in Example 1, and disperse the catalyst (1) so that the dispersion concentration of catalyst (1) is 3.8% by weight, and then blow in hydrogen from the bottom of the water tank. A bubbling tube (inner diameter 1 mm) was introduced, and hydrogen was blown at a flow rate of 0.71 NL / min, and the treatment with nitrate nitrogen-containing water was performed without using an ultrafine bubble reducing gas generator. At this time, the liquid temperature was maintained at 25 ° C., and the water tank was stirred at 200 rpm. During the treatment of nitrate nitrogen, the pH of the nitrate nitrogen-containing water was adjusted to a range of 5 to 6 with sulfuric acid having a concentration of 1% by weight. The size of hydrogen bubbles generated at this time was 1 mm or more. The results are shown in Table 1.
硝酸性窒素含有水の処理
比較例１において、バブリング管（内径０．２ｍｍ）１０本を導入して、水素の流量０.７１Ｌ/ｍｉｎで吹き込んだ以外は同様にして硝酸性窒素含有水の処理を実施した。このときに発生した水素ガスの気泡の大きさは、０．２ｍｍ以上であった。結果を表１に示した。
Treatment of nitrate-nitrogen-containing water Treatment of nitrate-nitrogen-containing water was the same as in Comparative Example 1 except that 10 bubbling tubes (inner diameter 0.2 mm) were introduced and blown at a hydrogen flow rate of 0.71 L / min. Carried out. The size of the hydrogen gas bubbles generated at this time was 0.2 mm or more. The results are shown in Table 1.
Claims (7)
A method for treating nitrate nitrogen-containing water, comprising contacting nitrate nitrogen-containing water with a catalyst for treating nitrate nitrogen-containing water in the presence of ultrafine bubble reducing gas.
2. The method for treating nitrate-containing water according to claim 1, wherein the ultrafine bubble reducing gas has an average value of 0.1 mm or less.
The method for treating nitrate-containing water according to claim 1 or 2, wherein the reducing gas is hydrogen gas.
The method for treating nitrate nitrogen-containing water according to any one of claims 1 to 3, wherein the utilization rate of the reducing gas is in the range of 30 to 100%.
The nitrate nitrogen-containing water treatment catalyst is metal fine particles or particles in which the metal fine particles are supported on an inorganic oxide carrier and / or a carbon carrier, and the average particle diameter of the metal fine particles is in the range of 1 to 200 nm. 5. The method for treating nitrate nitrogen-containing water according to claim 1, wherein the average particle diameter of the nitrogen is in the range of 5 nm to 500 μm.
6. The metal according to claim 1, wherein the metal is one or more metals or alloys selected from Pt, Au, Ag, Pd, Ru, Cu, Ni, W, V, Mo, and Fe. Any one of the processing methods of nitrate nitrogen containing water.
The inorganic oxide support is one or more oxides or composite oxides selected from SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , In 2 O 3 , and ZnO. The method for treating nitrate nitrogen-containing water according to any one of claims 1 to 6.
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| JP2011025169A (en) * | 2009-07-27 | 2011-02-10 | Japan Atomic Energy Agency | Catalyst for reductive decomposition of nitrate ion |
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| CN106219666A (en) * | 2016-07-06 | 2016-12-14 | 广西大学 | A kind of Pt doping In2o3the method of PFOA in photocatalytic degradation water |
| JP2019178386A (en) * | 2018-03-30 | 2019-10-17 | 日揮触媒化成株式会社 | Alloy particle dispersion liquid and method for producing the same |
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