JP4052549B2 - Photocatalyst based on granulated artificial lightweight aggregate, production method thereof and use thereof - Google Patents
Photocatalyst based on granulated artificial lightweight aggregate, production method thereof and use thereof Download PDFInfo
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- JP4052549B2 JP4052549B2 JP2001353108A JP2001353108A JP4052549B2 JP 4052549 B2 JP4052549 B2 JP 4052549B2 JP 2001353108 A JP2001353108 A JP 2001353108A JP 2001353108 A JP2001353108 A JP 2001353108A JP 4052549 B2 JP4052549 B2 JP 4052549B2
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- Prior art keywords
- photocatalyst
- water
- lightweight aggregate
- particles
- granulated
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- 239000011941 photocatalyst Substances 0.000 title claims description 175
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 239000002245 particle Substances 0.000 claims description 89
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 52
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 28
- 239000000758 substrate Substances 0.000 claims description 26
- 239000007789 gas Substances 0.000 claims description 23
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 22
- 239000003973 paint Substances 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 21
- 239000000463 material Substances 0.000 claims description 18
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 15
- 239000000377 silicon dioxide Substances 0.000 claims description 14
- 238000003860 storage Methods 0.000 claims description 14
- 239000011230 binding agent Substances 0.000 claims description 13
- 238000007667 floating Methods 0.000 claims description 9
- 230000005484 gravity Effects 0.000 claims description 9
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 8
- 230000001678 irradiating effect Effects 0.000 claims description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 6
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- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 claims description 3
- 239000004575 stone Substances 0.000 claims description 3
- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 claims description 3
- 229910001930 tungsten oxide Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 2
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 239000000919 ceramic Substances 0.000 claims description 2
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 claims description 2
- 239000000835 fiber Substances 0.000 claims description 2
- 229910003437 indium oxide Inorganic materials 0.000 claims description 2
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 claims description 2
- 150000002739 metals Chemical class 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 239000004745 nonwoven fabric Substances 0.000 claims description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims 1
- 239000004599 antimicrobial Substances 0.000 claims 1
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- 239000011733 molybdenum Substances 0.000 claims 1
- -1 woods Substances 0.000 claims 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 26
- 241000195493 Cryptophyta Species 0.000 description 20
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- 238000000926 separation method Methods 0.000 description 5
- 238000002834 transmittance Methods 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 4
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- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 4
- 239000002023 wood Substances 0.000 description 4
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
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- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 241001465754 Metazoa Species 0.000 description 2
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
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- 239000010410 layer Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229920006327 polystyrene foam Polymers 0.000 description 2
- 235000019353 potassium silicate Nutrition 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
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- 230000001629 suppression Effects 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
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- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- KVGZZAHHUNAVKZ-UHFFFAOYSA-N 1,4-Dioxin Chemical compound O1C=COC=C1 KVGZZAHHUNAVKZ-UHFFFAOYSA-N 0.000 description 1
- 241000251468 Actinopterygii Species 0.000 description 1
- 102000010637 Aquaporins Human genes 0.000 description 1
- 108010063290 Aquaporins Proteins 0.000 description 1
- 241001561902 Chaetodon citrinellus Species 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241000192700 Cyanobacteria Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 241000588724 Escherichia coli Species 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000004640 Melamine resin Substances 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
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- 238000007605 air drying Methods 0.000 description 1
- 230000005791 algae growth Effects 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 238000009360 aquaculture Methods 0.000 description 1
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- 239000004568 cement Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
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- 239000002019 doping agent Substances 0.000 description 1
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- 239000003562 lightweight material Substances 0.000 description 1
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- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
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- LNDHQUDDOUZKQV-UHFFFAOYSA-J molybdenum tetrafluoride Chemical compound F[Mo](F)(F)F LNDHQUDDOUZKQV-UHFFFAOYSA-J 0.000 description 1
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- 230000001954 sterilising effect Effects 0.000 description 1
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- 238000004381 surface treatment Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
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- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 1
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- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/30—Wastewater or sewage treatment systems using renewable energies
- Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy
Landscapes
- Agricultural Chemicals And Associated Chemicals (AREA)
- Physical Water Treatments (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
- Disinfection, Sterilisation Or Deodorisation Of Air (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、光触媒体及びその製造方法並びにその用途に関し、特に、ガラス質殻で被覆されている造粒型人工軽量骨材を基体とした光触媒体及びその製造方法並びにその用途に関する。
【０００２】
【従来の技術】
光触媒粒子それ自体は微粒子であり、そのまま光触媒として用いると反応後の固気分離や固液分離が困難なため、光触媒粒子より大きな基体上に光触媒粒子を固定させて利用する試みがなされている。
【０００３】
しかし、実用材料として要求される光触媒能、光触媒粒子の担持強度、光触媒体の強度等の特性を満足するものはなく、しかも高価であった。
【０００４】
また、太陽光の利用による水処理を想定すれば、光の利用効率の点から考えて、光触媒体も水に浮遊する方が有利と考えられるが、安価で、長期間水への浮遊持続性が高い無機材料はなかった。
【０００５】
さらには光触媒を用いてアルデヒド、メルカプタン、アンモニア等の有害ガスを分解・除去したり、工場排水、鉱業排水、農業排水、湖沼、海水等の汚水を浄化・抗菌をしたり、ため池、貯水槽、浄化槽、養殖槽等の藻の繁殖付着を抑制する簡便な方法が要望されている。
【０００６】
特にため池、貯水槽、浄化槽、養殖槽等で繁殖する藻類は、美観を損ねるだけではなく、その種類によっては魚、動植物、ならびに人間に対してまでも悪影響を及ぼす場合がある。藻類に由来する毒性物質は毒性が強いので、様々な動物たちに感染すると病気になったり、死に至らしめることもあり得るため、このような生物への傷害をさけるためにも適切な処置が必要となる。一般的には藻の繁殖付着防止のために、溶解性の薬剤型防藻剤が投与される場合が多いが、一時的には有効であるが、効果の持続のためには定期的投与が必要となり、強力な薬剤になると藻類以外の生物に対してまでも影響が及ぶ。すなわち、従来の防藻剤は、安全性と効果のバランスが維持しにくく、しかも定期的に投与することが前提となるため煩雑となるという短所があった。
【０００７】
【発明が解決しようとする課題】
本発明は、実用に十分な光触媒能を有し、光触媒粒子の担持強度に優れる、すなわち長寿命であり、太陽光の利用に有利なように水浮遊持続性が高く、取り扱いが容易である光触媒体を安価に提供することを課題とする。
【０００８】
【課題を解決するための手段及び発明の実施の形態】
本発明者らは、上記問題点に鑑み、まず基体材料について鋭意研究を行った。
【０００９】
その結果、微細な中空ガラス粒子を集合させたものを基体に用いる場合、基体表面は凹凸形状になっているため、これに光触媒を担持させた光触媒体の活性は高いものとなることがわかった。
【００１０】
しかし、基体表面を形成する中空ガラス粒子層の粒子間はわずかに隙間があり、比較的内部までその構造が連続しているため、場合によっては毛管現象で光触媒塗料が内部にまで浸透し、光が当たる表面でしか効果を発揮しない光触媒にとって内部に浸透している光触媒粒子は無駄になっていることが明らかとなった。
【００１１】
このことより、光触媒粒子を無駄なく、従ってより安価に、かつ効率的に効果を発揮させるための光触媒用基体について、光触媒粒子との接着性や固定強度、ならびに光触媒活性に注目して、さらに研究を重ねた結果、基体表面は隙間のない緻密なガラス質殻構造であることが望ましいという結論に至った。
【００１２】
また、廃棄物である砕石廃泥を出発原料とすることにより、安価に、しかも所望の特性を有する、表面にガラス質殻構造を有する無機材料が得られることがわかった。
【００１３】
さらには光触媒担持方法についても研究した結果、光触媒粒子濃度を５〜３０ｗｔ％にした光触媒塗料を用いて担持することにより、数回に渡って担持処理を行うことなく、１回だけの担持操作、もしくは塗布操作において光触媒粒子を無駄なく固定でき、高い光触媒能を示す光触媒体が得られることが明らかとなり、本発明を完成させたものである。
【００１４】
本発明者らは、上記問題点に鑑み鋭意研究を行った結果、特定の形状及び粒径を有するガラス質殻で被覆されている造粒型人工軽量骨材を基体とし、光触媒粒子濃度が５〜３０ｗｔ％の光触媒塗料を用いて前記基体表面に光触媒粒子を担持させることにより、１回の担持処理で光触媒粒子を無駄なく、効率的に担持することが可能となり、しかも光触媒粒子の担持強度や光触媒能に優れると同時に、取り扱いや作業性にも優れた光触媒体が得られることを見出し、本発明を完成させた。
【００１５】
すなわち、本発明は、ガラス質殻で被覆されている造粒型人工軽量骨材を基体とし、該ガラス質殻の表面に無機物質を結合剤として光触媒粒子を固定させたことを特徴とする光触媒体に関する。また、結合剤としての水性無機物質及び水に光触媒粒子を分散させてその光触媒粒子濃度を５〜３０ｗｔ％に調整した塗料に、ガラス質殻で被覆されている造粒型人工軽量骨材を浸漬することにより、該ガラス質殻の表面に前記塗料を付着させた後、１００〜９００℃で加熱処理することを特徴とする光触媒体の製造方法等に関する。
【００１６】
ここでいう造粒型人工軽量骨材とは、砕石廃泥、膨張性頁岩、膨張性粘土、フライアッシュ等の焼却灰、シラス等の火山噴出物、シラスバルーン等の火山噴出発泡粒子、ならびに無機性汚泥などを造粒後、８００〜１３００℃付近で焼成することで得られる人造の骨材をいう。また、ガラス質殻とは、前記造粒型人工軽量骨材の表面で緻密なガラス質の殻が形成された部分をいい、このガラス質の殻は結合剤（無機物質）との接着性に優れ、光触媒粒子に多くの活性点を形成しつつ強固に担持することができる。このようなガラス質殻は、造粒後の処理により形成されるものであり、例えば造粒後にフリットを表面処理して低温焼成することで得られる。光触媒粒子を固定する場合、固定効率は特定範囲の光触媒塗料濃度を選択するとよい。また、造粒型人工軽量骨材の内部構造は、主にスポンジ状で多数の微細気泡を有し、これには中空単孔も含み、主として比重は０．１〜１．８程度である。この構造により、光触媒塗料は内部にまで浸透せず塗布量をコントロールしやすく、比重の設定が容易である。
【００１７】
前記造粒型人工軽量骨材の形、及び大きさは、使用する環境によって適宜選択されるものであるが、光触媒体の取り扱いや固気、及び固液分離の容易性から判断して、形状がほぼ球形であり、平均粒径が１〜５０ｍｍであることが好ましい。
【００１８】
また、水に浮くような軽量材料でありながら、実用強度を有するものが良く、つまりは前記造粒型人工軽量骨材の絶乾密度が０．４〜０．９ｇ／ｃｍ3、かつ粒強度が２０〜６０ｋｇ／ｃｍ2であることが好ましい。
【００１９】
さらには、前記基体の１ヶ月間の水浮遊率が重量基準で９５％以上を達成する基体が好ましく、結果として前記基体表面に光触媒を担持した光触媒体の１ヶ月間の水浮遊率は重量基準で９０％以上に達する。
【００２０】
本発明の光触体又はその製造に使用される光触媒粒子としては、酸化チタン、酸化亜鉛、酸化鉄、チタン酸カリウム、酸化タングステン、チタン酸ストロンチウム、硫化モリブデン、及び酸化インジウムの少なくとも１種を用いることができ、中でも酸化チタン、酸化亜鉛、酸化鉄、チタン酸ストロンチウム及び酸化タングステンが好ましく、特に酸化チタンが好ましい。さらにそれらの光触媒粒子に適当なドーパントを添加したものも用いることができる。
【００２１】
前記光触媒粒子が酸化チタンの場合はアナタ−ゼ型が好ましいがルチル型も使用できる。また比表面積は２０〜５００ｍ2／ｇが好ましく、特に１００〜４００ｍ2／ｇがさらに好ましい。また酸化チタン粒子径は、一次粒径で０．０１〜１μｍが好ましく、さらに好ましくは０．０２〜０．１μｍであって、その造粒物や焼結体でも良い。造粒物や焼結体にして粒径を大きくすると、用途によって無機物質の膜厚が比較的大きい場合に、後述のシリカ膜等の膜から光触媒粒子を頭出し（活性点としての露出）できるため光触媒活性が有効に現れる。
【００２２】
また、酸化チタンには、触媒活性を向上させるため、Ｗ、Ｓｎ、Ｓ、Ｍｏ、Ｖ、Ｍｎ及びＺｎ等の元素を含む金属酸化物を含有させることもできる。
【００２３】
酸化チタン同様に他の光触媒粒子においても純度は特に規定されず、必要によってはバンドギャップの調整を目的に適当な不純物を添加して用いることができる。
【００２４】
また本発明の光触媒体には活性炭やゼオライト等の有害物質を吸着させる機能性物質を含有させること、抗菌性金属を担持・含有させることもできる。
【００２５】
本発明の光触媒体又はその製造において、光触媒粒子を前記造粒型人工軽量骨材に固定させるための結合剤としての無機物質には、シリカ、アルミナ、酸化チタン、又はフリットを用いることができる。ここでの無機物質としての酸化チタンは過酸化チタンも含む。そして、本発明において、前記基体の表面には結合剤と類似物性のガラス質殻を有するので、結合剤による接着性が高く、特にシリカとの接着性に優れる。ガラス質殻の緻密で隙間の無い表層構造により、接着性が向上するとともに、光触媒粒子を基体上の薄膜に含ませて多くの活性点を持たせた状態へ分散させ固定することができる。
【００２６】
結合剤がシリカの場合、光触媒粒子含有のシリカ膜と、シリカを主成分とする基体である造粒型人工軽量骨材との固定性は最も良好となる。膜厚が厚くなり過ぎると光触媒効果に対して無駄であり、膜強度も低下する傾向があることより膜厚は１００μｍ以下であることが好ましい。光触媒粒子を含有したシリカ膜中の光触媒粒子の割合は、１０〜９０重量％が好ましく、より好ましくは２０〜８５重量％、最も好ましくは４０〜８０重量％である。
【００２７】
本発明の光触媒体は紫外線の照射による光触媒効果でアルデヒド、メルカプタン等の悪臭ガス、ＮＯｘ、ダイオキシン等の除去、藻の繁殖付着抑制、及び殺菌性に優れた効果を示すとともに、実用強度を有し、光触媒体の加工性、耐候性及び被処理物との分離操作性に優れている。
【００２８】
使用される基体の選択に関し、本発明の造粒型人工軽量骨材は、結着剤や光触媒粒子の量によって、見かけの比重を水よりも大きくも小さくもでき、例えば水中に浮遊及び／又は沈降するようにできる。すなわち、用途に必要な比重を選択できる。水の比重前後に設定された基体を用いる光触媒体は、後述する水の浄化、水の殺菌、ならびに藻の繁殖付着抑制などに、そのまま幅広く使用できる。
【００２９】
本発明の光触媒体は代表的には、水性無機物質としての水性シリカゾル及び水に、前記光触媒粒子を分散させ、光触媒粒子濃度を５〜３０ｗｔ％に調整した塗料に、前記造粒型人工軽量骨材の基体を浸漬させることにより、その基体表面に前記塗料を付着させた後、１００〜９００℃で加熱処理することによって製造することができる。
【００３０】
前記製法において、塗料中の光触媒粒子濃度は、５〜３０ｗｔ％、好ましくは８〜３０ｗｔ％である。５ｗｔ％より少ないと高光触媒能のものを得るためには、数回以上の浸漬担持処理、もしくは塗布操作が必要となるため作業が繁雑となり、結果としてコストが高くなるため好ましくない。また、３０ｗｔ％より多くなっても光触媒能が高くなることはなく、塗料の粘性が高くなり基体表面に光触媒粒子が過剰に付着するため無駄であり、光触媒膜厚が厚くなり過ぎたことによって光触媒膜が剥離することもあるため好ましくない。
【００３１】
前記塗料への前記造粒型人工軽量骨材の浸漬は、わずか１回の浸漬処理にて実現できるため作業が軽減され、結果として低コストで高光触媒活性を有する光触媒体を製造できる。浸漬処理した前記造粒型人工軽量骨材はメッシュにより、光触媒塗料と分離できるが、骨材の粒子間に介在する光触媒塗料を速やかに除去するために、光触媒塗料中にアルコールを添加することもできる。
【００３２】
前記塗料付着後の加熱処理は一般的には１００〜９００℃が好ましく、１００〜８００℃がより好ましい。この範囲に規定したのは、１００℃より低くなると水性シリカゾルのゲル化に長時間を要し、膜強度を得にくいためであり、９００℃より高くなると光触媒粒子の活性が低くなるからである。
【００３３】
なお、使用する水性シリカゾルはその粒径が０．１〜２０ｎｍの微粒子タイプであり、１〜１０ｎｍのものがより好ましい。水性シリカゾルの粒径が大きいと、光触媒粒子との接触面積が小さくなるため、接着力が弱くなるので好ましくない。このシリカゾルは脱Ｎａ処理した水性シリカゾルであることが必要である。Ｎａイオンを残存させて塩基性のゾルとしている水性シリカゾルは、塗料としたときにＮａイオンが光触媒粒子に吸着して光触媒能を大幅に減衰させるため、光触媒粒子の固定用バインダーとしては実用性がない。脱Ｎａ処理した水性シリカゾルは、例えば、珪酸ソーダを原料にイオン交換樹脂で脱Ｎａして得ることができる。
【００３４】
水性シリカゾルと光触媒粒子表面の結合はゾル粒子と光触媒粒子の接触点で生じるが、前記水性シリカゾルは本発明で好ましいと考えられる光触媒粒子の一次粒子径０．０１〜１μｍに対して適度の大きさを有するため、光触媒粒子表面にはシリカと結合していない活性サイトが多く存在する。このため光触媒能は高く保持される。
【００３５】
光触媒粒子の一次粒径(Ａ)と水性シリカゾルの粒径(Ｂ)の比(Ａ／Ｂ)が２００〜２の範囲であれば、光触媒粒子の一次粒子に接着する水性シリカゾルの個数は、光触媒固定膜としての接着力と分解能のバランス上最適な状態となる。前記(Ａ／Ｂ)が２００より大きい場合、接着力は強いが水性シリカゾルが酸化チタン表面の活性点をほとんど覆ってしまうため分解能はほとんど認められなくなる。一方、(Ａ／Ｂ)が２より小さい場合、分解能は高いが固定膜としての接着力が極端に低下する。
【００３６】
また、塗料を作製する際の、光触媒粒子に対する水性シリカゾルの添加比率は、ＳｉＯ2基準で１０〜９００ｗｔ％が好ましく、より好ましくは１５〜４００ｗｔ％、最も好ましくは２５〜１５０ｗｔ％である。水性シリカゾルの添加比率が１０ｗｔ％より少ないと光触媒膜の強度が低くなり、またシリカゾルの添加比率が９００ｗｔ％より多いと塗膜中の酸化チタン濃度が低下するため、光触媒塗膜の単位面積当たりの光触媒能が低下するので好ましくない。
【００３７】
また水性シリカゾルの添加量を上記の範囲で多くしても光触媒能はほとんど低下せず、塗膜の強度はその添加量にほぼ比例して向上する。第一層を覆った後の余分の水性シリカゾルはシリカゾル粒子同士でその上にシロキサン結合のネットワークを形成し、塗膜強度の強化に貢献している。水性シリカゾルからできるシリカの積層はｎｍオーダーの空孔が多く存在し、塗膜の空隙率は３０〜７０％と比較的高く保たれるので、被分解ガスの吸着と反応生成ガスの脱離は容易で光触媒反応を律速することは無いと考えられる。
【００３８】
水性シリカゾルの粒径が０．１ｎｍより小さいものは、オリゴマーの性質に近く不安定でゲル化しやすいため長期保存での安定性が必要な塗料用のバインダーとしては適さない。また粒径が１０ｎｍより大きいと、シリカゾル同士及びシリカゾルと光触媒粒子、更にはシリカゾルと基体との接着層との接着力が弱く、塗膜としての充分な剥離強度がとれないので好ましくない。
【００３９】
シリカゾルの結合を強固にする目的で、前出光触媒塗料に低濃度の酸、または少量の珪酸ソーダあるいはアルミン酸ソーダを添加することで、塗膜の剥離強度を向上させることも可能である。
【００４０】
被分解ガスの種類によっては、塗膜に光触媒粒子以外の吸着剤を併用した方が光触媒効果を高くできる場合もある。例えばＮＯｘ浄化用として用いる場合には、吸着剤としてゼオライト、酸化亜鉛微粉末、チタン工業製吸着剤ＴＺ−１００等を酸化チタンに対して１〜３０ｗｔ％添加することで、ＮＯｘ浄化能を大幅に向上させることができる。
【００４１】
また、本発明の光触媒体は、前記造粒型人工軽量骨材を前記塗料に浸漬するだけでなく、前記塗料を塗布することによっても製造することができる。
【００４２】
また、前記基体への光触媒粒子の固定は、塗料に限らず、非晶質光触媒粒子の懸濁液、もしくは低結晶性光触媒粒子懸濁液を用いた公知の方法によって行ってもよい。
【００４３】
本発明の光触媒体を、繊維、樹脂、樹脂成形体、不織布、陶磁器、金属、木材、及び合金の群より選ばれる少なくとも１種からなる袋状又は網目状の収納容器に入れて光触媒体収納物とすることができる。
【００４４】
ここで、前記収納容器に浮遊体を入れてもよく、この浮遊体として、発泡スチロール、中空フィラー、木材、プラスチックの群より選ばれる少なくとも１種とすることができる。
【００４５】
さらに、本発明によれば、前述の光触媒体又は、前述の光触媒体収納物に、有害ガスを通過させると共に、紫外線を含有した光を前記容器又は前記収納物に照射することにより、有害ガスを分解・除去することができる。
【００４６】
ここでいう有害ガスとは、アルデヒド、メルカプタン、アンモニア、ＮＯｘ、ダイオキシン等を含むものである。
【００４７】
該光触媒体は公園や街路樹等の適当な場所にそのまま配置して使用することもできる。
【００４８】
また、簡便かつ安価であり、しかも効率良く有害ガスを分解・除去するためには、光触媒体をカラム中に入れて使用するのもよい。すなわち、紫外線を透過させる材質のカラム中に該光触媒体を入れ、この中に有害ガスを強制もしくは自然通過させ、太陽光もしくは紫外線を含有したランプを照射することにより有害ガスを分解・除去することができる。
【００４９】
さらに環境中に排出されるダイオキシン類の除去に対しても有効である。ダイオキシンは燃焼における第１次的な発生抑制が十分になされている場合でも、排ガスが２００〜６００℃の温度帯で未燃分や触媒作用を持つダストに接触するとダイオキシン類の２次生成が起こるとされている。このような環境中に排出される１次生成及び２次生成のダイオキシンを排ガス側から除去するのに、本発明の光触媒体を用いることができる。例えば、焼却炉の煙突部に光触媒体を充填させたカラムを１段、もしくは多段的に取り付ける方法である。紫外線が透過するカラムであれば、太陽光の利用により吸着と同時に分解させることが可能であるが、カラムの取り外しを容易にしておけば、煙突部から吸着カラムを取り外し、これを別の場所にて太陽光、または紫外線ランプを照射させることにより、吸着物質を分解させることが可能となる。また、このものは繰り返し使用してもかまわない。
【００５０】
また、該光触媒体を紫外線を透過させる材質のフレーム等に入れて使用することもできる。この場合は、持ち運びが容易であり、設置、及び光触媒体の交換が容易であるという特徴を有する。
【００５１】
更に、前記光触媒体収納物を用いても有害ガスの分解・除去を同様に行うことができる。
【００５２】
さらに、本発明によれば、水中に浮遊及び／又は沈降するように比重を調整した前述の光触媒体又は前述の光触媒体収納物に水を通過させると共に、紫外線を含有した光を照射することにより水を浄化することができる。
【００５３】
ここでいう水とは、工場排水、鉱業排水、工業用水、農業用水、飲料水、湖沼、河川水、海水等を含むものである。これらの存在する湖岸、川岸、海岸、流水路、貯水槽内、濾過器内、下水道、あるいは水棲生物の飼養域内に本発明の光触媒体を用いて水の浄化を行うに当たり、これらの水と接触しうる箇所に、前記光触媒体を設置したり、あるいは前記光触媒体を水に投入したりして配置する。次に、配置した光触媒体に紫外線を含有した光を照射させ、水を浄化する。
【００５４】
紫外線を含有した光としては、例えば、太陽光や蛍光灯、ブラックランプ、キセノンフラッシュランプ、水銀灯などの光があげられる。この中でも、特に、３００〜４００ｎｍの紫外線を含有した光が好ましい。紫外線を含有した光の照射量や照射時間などは汚水の汚染の程度によって適宜設定できる。光触媒体に紫外線を含有した光を照射させる方法は適宜選択できるが、例えば、水面上部から照射したり、汚水の中に光源を設置して照射したり、水槽内の汚水を浄化する場合には、水槽の側面部から照射したりすることもできる。また、本発明の光触媒体を汚水と接触しうる前記の箇所に配置し、次いで紫外線を含有した光を照射すると、照射を受ける箇所では、該光触媒体の光触媒機能によって該汚水を浄化でき、しかも、紫外線を含有した光の照射を受けない同じ反応系内の箇所では、反応系内で発生した水質浄化機能を有する微生物が基体に付着したり、予め水質浄化機能を有する微生物を光触媒体に付着させることによって、該微生物による浄化を行うことができる。
【００５５】
前記汚水の浄化方法における対象処理物について言えば、水中に残っている遊離塩素やトリハロメタン等の有機物を分解・除去することができ、また、水質汚濁防止法の改訂によって規制が強化された鉱業排水中に含まれるセレンの除去にも利用できる。
【００５６】
後者の場合、鉱業排水中に光触媒体を投入し太陽光を利用する方法、また、カラム中に本発明の光触媒体を入れ、この中に鉱業排水を通過させ紫外線含有照射ランプを当てる方法等により、６価のセレンを４価もしくは０価に還元して回収するものである。
【００５７】
また、本発明の光触媒体を用いた汚水の浄化方法の応用として、該光触媒体を投入した水中に配管を浸漬して、有害ガスを通過させバブリングさせることで有害ガスを分解させることもできる。
【００５８】
さらに装置的には紫外線を含有した光の光触媒体への照射効率を高めるため、光の反射板を設けたり、容器内壁面を鏡面仕上げとしたり、容器内壁面に鏡もしくはこれに類するものを設置したりすることもできる。
【００５９】
本発明の光触媒体を用いて、例えば水の浄化を行う場合、水の流出口にネット等を張って光触媒体の流出を防止することができるが、流出口径よりも大きな前記収納容器に光触媒体を入れ、光触媒体収納物として使用すれば、流出は防止でき、かつ、回収も容易にできる。
【００６０】
また、前記光触媒体収納物を水に浮遊させて使用したい場合は、前記収納容器に浮遊体を入れてもよい。前記浮遊体は発泡スチロール、中空フィラー、木材、プラスチックス等が使用できる。逆に水中に沈めて固定したいときや、道路や街路樹等に置いたときに風等による移動を避けたいときは、可能であればロープ、針金、接着剤等で固定すればよいが、前記収納容器に固定材として、木材、石及び金属塊を入れてもよい。
【００６１】
更に、本発明によれば、水中に浮遊及び／又は沈降するように比重を調整した前述の光触媒体又は前述の光触媒体収納物を使用して藻の繁殖付着を抑制することができる。
【００６２】
藻類が発生し易い環境の、または既に発生している、貯水槽内、濾過器内、下水道、ため池等に、該光触媒体、あるいは該光触媒体収納物を設置したり、単に水に投入したりして配置する。次に、配置した光触媒体、もしくは該光触媒体収納物に紫外線を含有した光を照射させ、藻の繁殖付着を抑制することができるが、自然に発生したため池等を含み屋外にある施設の場合は、室内に比して積極的に太陽光を利用できるので、人工灯を用いなくても良い。
【００６３】
前述したように、本発明における防藻剤は水中に投じるだけで藻の繁殖付着に効果を示し、機械装置を設置する必要がなく、従って、低コストで、しかも簡単に使用することができる。
【００６４】
いずれの用途においても収納容器内には当該光触媒体のほか、光触媒効果補助剤として、活性炭やゼオライト等の有害物質吸着剤及びこれらの造粒物や成型物、抗菌物質及びこれの造粒物や成型物の適量を同時に入れることができる。
【００６５】
また当該光触媒体は、セメント等でできた構造物の表面に頭出しするように固着させて使用することもでき、光触媒体自身を接着剤を用いて、板状、筒状等に加工した形で使用することもできる。
【００６６】
以下に実施例を挙げて、本発明の内容をより詳細に説明するが、これら実施例はあくまでも例示であり、本発明の範囲はこれに限定されるものではない。
【００６７】
【実施例】
造粒型人工軽量骨材（Ａ）、及び造粒型人工軽量骨材（Ｂ）の製造方法
水ガラスを用いてシラスを造粒し、ほぼ球形の造粒物を得た。常温にて約１週間養生後、Li2O-Na2O-B2O3-Al2O3-P2O5組成のフリットを造粒粉の表面にまんべんなく付着させ、キルンを用いて約９００℃で焼成して、ガラス質殻で被覆された造粒物を得た。焼成した造粒物はふるいで選別し、平均粒径１５ｍｍの造粒型人工軽量骨材（Ａ）、及び平均粒径３ｍｍの造粒型人工軽量骨材（Ｂ）をそれぞれ得た。なお（Ａ）の絶乾密度は０．７８、粒強度は４６ｋｇ／ｃｍ2、１ヶ月間の水浮遊率は９８％であり、（Ｂ）は順に０．５１、３１ｋｇ／ｃｍ2、９９％であった。
【００６８】
造粒型人工軽量骨材（Ｃ）
ガラス質殻で被覆されている造粒型人工軽量骨材の１種である、市販の平均粒径１５ｍｍの愛媛砕石株式会社製ヒメライトを用いた。このものの絶乾密度は０．４６、粒強度は５５ｋｇ／ｃｍ2、１ヶ月間の水浮遊率は１００％であった。
【００６９】
シラスバルーン集塊物の製造方法
シラスバルーンを水ガラスを用いて集塊させ、キルンを用いて約９００℃で焼成した。焼成物をふるいを用いて選別し、平均粒径が約１５ｍｍのシラスバルーン集塊物を得た。
【００７０】
実施例１
光触媒粒子としての酸化チタン（アナターゼ型 比表面積３４０ｍ2／ｇ）１２ｇ、結合剤としての水性シリカゾル（粒径５ｎｍ、二酸化チタンの一次粒径／シリカゾルの粒径＝４）２３．４ｇ、純水１２．６ｇを３ｍｍのガラスビーズ６０ｇとともに１２０ｍｌのガラス瓶に仕込み、レッドデビル社製のペイントコンディショナーで３０分間分散、混合して、シリカゾルを含有する塗料とした。本塗料中の光触媒粒子濃度は２５ｗｔ％である。
【００７１】
さらに、平均粒径１５ｍｍの造粒型人工軽量骨材(Ａ)を基体として、前記塗料中に浸漬し、ふるいにて塗料と光触媒粒子を固定した造粒型人工軽量骨材とを分離した。一昼夜風乾後、１１０℃で焼き付けして光触媒粒子含有のシリカ膜を基体に固定化した。７００℃で１時間の熱処理を行い光触媒体を得た。
【００７２】
実施例２
実施例１において、基体として平均粒径３ｍｍの造粒型人工軽量骨材（Ｂ）を用いる以外は同様にして行った。
【００７３】
実施例３
実施例１において、基体として造粒型人工軽量骨材(Ｃ)を用いる以外は同様にして行った。
【００７４】
実施例４
実施例１の試料４０ｇを１０ｃｍ×１０ｃｍ×２ｃｍの陶器製網状容器内に入れて光触媒収納物とした。
【００７５】
【比較例】
比較例１
造粒型人工軽量骨材(Ａ)のみを試料とした。
【００７６】
比較例２
造粒型人工軽量骨材(Ｃ)のみを試料とした。
【００７７】
比較例３
比較例１の試料をガラス製網状容器内に入れて収納物とした。
【００７８】
比較例４
実施例１の塗料調整時の純水量を３５０ｇ、ガラスビーズ量を２５０ｇとし（光触媒粒子濃度が所望濃度より低い）、５００ｍｌ瓶を用いる以外は同様にして行った。
【００７９】
比較例５
実施例１の酸化チタンを（水に分散させた塗料ではなく）アクリル−メラミン樹脂に分散させた塗料を基体に塗布した以外は同様にして行った。
【００８０】
比較例６
実施例１において、基体として平均粒径約１５ｍｍの前記シラスバルーン集塊物（ガラス殻膜は被覆されていない）を用いたことと、塗料中への浸漬回数を２回にした以外は同様にして行った。
【００８１】
試験例
１．剥離試験
走査型電子顕微鏡観察を用いて試料表面を観察し、光触媒体上に光触媒粒子が固定化されていることを確認した後、光触媒体を水中に入れ１０分間超音波をかけ、光触媒体を水と分離した後の、水の透過率を測定した。透過率９５％以上を○、９５％未満を×とした。
【００８２】
２．耐候性試験
光触媒体にスガ試験機（株）製デューパネル光コントロールウェザーメーターを使用して、５００時間の紫外線照射を行った後、光触媒体表面の色調の変化を調べ、１記載の剥離試験条件に準じ、剥離試験を行い透過率を測定した。視覚的に変色が認められず、剥離試験での透過率が９５％以上である場合を○とし、変色が認められるかもしくは、剥離試験による透過率が９５％未満の場合を×とした。
【００８３】
３．色素の分解試験
有機色素オレンジ１を純水中に溶解し、オレンジ１濃度が１０ｐｐｍの溶液を調整した。１０ｐｐｍオレンジ1溶液の２５ｍｌ、及び回転子1個を入れた５０ｍｌビーカー中に、試料８個を投じた後、マグネチックスタラーを用いて緩やかに攪拌し、試験終了まで攪拌を継続させた。攪拌開始から３０分間目に５ｍｌを採水し、０．４５μｍディスクフィルターにてろ過した溶液の４７５ｎｍにおける吸光度Ａt0を測定した。続けてＵＶを１時間照射（ブラックライト、紫外線強度２．８ｍＷ／ｃｍ2）し、０．４５μｍディスクフィルターでろ過した溶液の４７５ｎｍ吸光度Ａt1を測定した。以下の式に基づき色素分解率を算出した。
分解率＝｛（Ａt0−Ａt1）/Ａt0｝×１００
＊ 吸光度測定：JASCO社製分光光度計UBEST５０型
【００８４】
４．ＮＯｘの浄化試験#試験法、試験装置、及び試験条件を以下に記す。
【００８５】
＜試験法＞
１．評価用試料を２個直列につないだシャーレ型反応容器の両方に入れた。
２．ボンベからのＮＯｘガスを空気に混合してバイパスで流し、ＮＯｘ濃度２００ｐｐｂ、空気流量１Ｌ／分で安定させた。
３．反応容器にガスを流してから３０分後、紫外線強度０．１ｍＷ／ｃｍ2で照射を開始した。紫外線を照射する直前のＮＯｘ濃度（Ｖint）を測定した。
４．紫外線照射開始から３０分後のＮＯｘ濃度（Ｖ３０）を測定した。
ＮＯｘ浄化率は以下のように定義した。
ＮＯｘ浄化率（％）＝｛（Ｖint−Ｖ３０）／Ｖint｝×１００
【００８６】
＜試験装置＞
ＮＯｘ測定装置：計測器サービス（株）ＭＬ９８４１Ａ
反応容器 ：(有)ビドロ化学 シャーレ式光反応容器（内径１５６ｍｍ深さ３２ｍｍ）ガラス蓋をテフロン（登録商標）リングを挟んで、ボルトで本体に固定し、側面のガラス管を通じてガスを流通させた。
原ガス ：ＮＯ／Ｎ2 ０．１％のガスボンベ
流量調整 ：（株）コフロック製サーマルマスフローコントローラー
配管 ：テフロン（登録商標）管を用いた。
【００８７】
＜試験条件＞
ＮＯｘ濃度 ：約２００ｐｐｂ
ガス流量 ：１Ｌ／ｍｉｎ．
評価用試料 ：１０ｃｍ×１０ｃｍ×１ｃｍの紙製の枠に試料４０ｇを入れた。
紫外線強度 ：０．１ｍＷ／ｃｍ2
測定温度 ：２０℃
湿度 ：空気はシリカゲルにより乾燥した。（室温で約６０％）
【００８８】
５．防藻試験
ため池より採取したアオコ（糸状藻類アナベナ）の５００ｍｌ、及び試験試料４０ｇ、または試験試料４０ｇを網状収納容器に入れた光触媒体収納物をそれぞれ１２０×１５０×７０ｍｍ3の樹脂製容器に投じ、夏場の屋外に２ヶ月間放置した。抗菌性金属粒子、及び光触媒粒子を固定していない火山噴出物発泡粒子成型物（ブランク））を同時に放置し藻の繁殖状態、ならびに容器への藻の付着状態を観察した。繁殖量がブランクに比して少ないもの、もしくは容器内壁への藻の付着が認められないものを○とし、繁殖量の増加、もしくは容器内壁への藻の付着が認められるものを×とした。
【００８９】
６．抗菌試験
大腸菌の菌液を添加したイオン交換水５０ｍｌに、試験試料２０粒、もしくは試験試料２０粒を網状収納容器に入れた光触媒体収納物を入れ、３０℃で保存、１０Ｗ蛍光灯にて光照射を行い、６時間後の生菌数を測定した。初期菌数は１０4であり、６時間後の生菌数を測定し、以下の式に基づき死滅率を算出した。
死滅率（％）＝｛（初期菌数−６時間後の生菌数）／初期菌数｝×１００
【００９０】
７．粒強度
圧縮試験機を用いて、直径約１０mm粒の破壊強度を測定した。単位面積当たりの破壊強度値を算出し、２０粒の平均値を粒強度とした。
【００９１】
８．絶乾密度
鉄製円筒状の２リットル升(正規容量Ｖｃｍ3)中に、ジギング法に従い乾燥試料を充填し、このときの充填試料重量（Ｗｇ）を測定した。以下の式に基づき絶乾密度を求めた。
絶乾密度（ｇ／ｃｍ3）＝Ｗ／｛Ｖ×（ｍ／１００）｝ｍ：実績率（％）
【００９２】
結果を表１に示す。
【表１】
表１の結果より、実施例の試料は、比較例のものより、色素分解率、ＮＯｘ浄化率に優れ、かつ藻の付着を抑制することが判明した。
【００９４】
【発明の効果】
本発明は、粒径を有するガラス質殻が被覆される特定の形状の造粒型人工軽量骨材を基体とし、その表面に光触媒粒子を固定させているので、使い勝手や光触媒活性に優れ、実用に耐え得る十分な強度を有するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocatalyst, a method for producing the same, and an application thereof, and more particularly, to a photocatalyst based on a granulated artificial lightweight aggregate covered with a glassy shell, a method for producing the photocatalyst, and an application thereof.
[0002]
[Prior art]
The photocatalyst particles themselves are fine particles, and if used as a photocatalyst, solid-gas separation or solid-liquid separation after the reaction is difficult. Therefore, attempts have been made to fix the photocatalyst particles on a substrate larger than the photocatalyst particles.
[0003]
However, none of them satisfy the properties such as photocatalytic ability, photocatalyst particle supporting strength, and photocatalyst strength required as practical materials, and they are expensive.
[0004]
Assuming water treatment using sunlight, it is considered advantageous to float the photocatalyst in water from the viewpoint of light utilization efficiency. There were no high inorganic materials.
[0005]
Furthermore, it uses photocatalysts to decompose and remove harmful gases such as aldehydes, mercaptans, and ammonia, purify and antibacterial wastewater such as factory effluents, mining effluents, agricultural effluents, lakes, and seawater. There is a demand for a simple method for suppressing the growth and adhesion of algae such as septic tanks and culture tanks.
[0006]
In particular, algae breeding in irrigation ponds, water storage tanks, septic tanks, aquaculture tanks, etc. not only detract from aesthetics, but depending on the type, algae may have an adverse effect on fish, animals and plants, and even humans. Since toxic substances derived from algae are highly toxic, infection with various animals can cause illness or even death, so appropriate measures are necessary to avoid injury to such organisms. It becomes. In general, soluble drug-type algae are often administered to prevent the growth and adhesion of algae, but it is effective temporarily, but periodic administration is necessary to maintain the effect. When it becomes necessary and becomes a powerful drug, it affects even organisms other than algae. That is, the conventional anti-algae agent has a disadvantage that it is difficult to maintain a balance between safety and effect and is complicated because it is premised on regular administration.
[0007]
[Problems to be solved by the invention]
The present invention is a photocatalyst having a photocatalytic ability sufficient for practical use, excellent in the carrying strength of the photocatalyst particles, that is, having a long lifetime, high water floating sustainability and being easy to handle so as to be advantageous for use of sunlight. It is an object to provide the body at a low cost.
[0008]
Means for Solving the Problem and Embodiment of the Invention
In view of the above problems, the present inventors first conducted intensive studies on the base material.
[0009]
As a result, it was found that when the aggregate of fine hollow glass particles was used for the substrate, the surface of the substrate was uneven, so that the photocatalyst carrying the photocatalyst on it had a high activity. .
[0010]
However, there is a slight gap between the particles of the hollow glass particle layer forming the surface of the substrate, and the structure is relatively continuous to the inside. Therefore, in some cases, the photocatalyst paint penetrates into the inside by capillary action, and light It was revealed that the photocatalyst particles penetrating the inside of the photocatalyst exhibiting an effect only on the surface where the light is applied are wasted.
[0011]
As a result, the photocatalyst particles are not wasted, and therefore, the photocatalyst bases that are effective at a lower cost and more efficiently focus on the adhesiveness and fixing strength with the photocatalyst particles and the photocatalytic activity. As a result, it was concluded that the substrate surface should desirably have a dense glassy shell structure with no gaps.
[0012]
Moreover, it turned out that the inorganic material which has a glassy shell structure on the surface which has a desired characteristic cheaply and by using the crushed stone waste mud which is waste as a starting material is obtained.
[0013]
Furthermore, as a result of studying a photocatalyst carrying method, by carrying using a photocatalyst coating material having a photocatalyst particle concentration of 5 to 30 wt%, only one carrying operation without carrying a carrying treatment for several times, Alternatively, the photocatalyst particles can be fixed without waste in the coating operation, and a photocatalyst exhibiting high photocatalytic activity can be obtained, and the present invention has been completed.
[0014]
As a result of intensive studies in view of the above problems, the present inventors have used a granulated artificial lightweight aggregate covered with a vitreous shell having a specific shape and particle size as a base, and have a photocatalyst particle concentration of 5 By supporting the photocatalyst particles on the surface of the substrate using a photocatalyst coating of ˜30 wt%, it becomes possible to efficiently support the photocatalyst particles in one support process without waste, and the support strength of the photocatalyst particles The inventors have found that a photocatalyst having excellent photocatalytic activity and also excellent handling and workability can be obtained, thereby completing the present invention.
[0015]
That is, the present invention provides a photocatalyst characterized in that a granulated artificial lightweight aggregate coated with a glassy shell is used as a base, and photocatalyst particles are fixed to the surface of the glassy shell using an inorganic substance as a binder. About the body. In addition, the granulated artificial lightweight aggregate covered with glassy shell is immersed in the coating material in which the photocatalyst particles are dispersed in water and inorganic water as a binder and the photocatalyst particle concentration is adjusted to 5 to 30 wt%. Thus, the present invention relates to a method for producing a photocatalyst, wherein the paint is adhered to the surface of the glassy shell and then heat-treated at 100 to 900 ° C.
[0016]
The granulated artificial lightweight aggregate here means crushed waste mud, expansive shale, expansive clay, incineration ash such as fly ash, volcanic eruptions such as shirasu, volcanic eruption foam particles such as shirasu balloon, and inorganic This refers to an artificial aggregate obtained by baking at about 800 to 1300 ° C. after granulation of the activated sludge. Further, the vitreous shell means a portion where a dense vitreous shell is formed on the surface of the granulated artificial lightweight aggregate, and this vitreous shell provides adhesion to a binder (inorganic substance). It is excellent and can be firmly supported while forming many active sites on the photocatalyst particles. Such a glassy shell is formed by a treatment after granulation, and can be obtained, for example, by subjecting a frit to surface treatment after granulation and firing at a low temperature. When fixing photocatalyst particles, the fixing efficiency may be selected from a photocatalyst coating concentration within a specific range. The internal structure of the granulated artificial lightweight aggregate is mainly sponge-like and has a large number of fine bubbles, including a hollow single hole, and the specific gravity is mainly about 0.1 to 1.8. With this structure, the photocatalyst coating does not penetrate into the interior, and the amount of coating can be easily controlled, and the specific gravity can be easily set.
[0017]
The shape and size of the granulated artificial lightweight aggregate are appropriately selected depending on the environment to be used, but the shape is determined based on the ease of handling and solid-gas and solid-liquid separation of the photocatalyst. Is substantially spherical and preferably has an average particle size of 1 to 50 mm.
[0018]
Also, it is good to have practical strength while being a lightweight material that floats on water, that is, the absolute dry density of the granulated artificial lightweight aggregate is 0.4 to 0.9 g / cm.ThreeAnd the grain strength is 20-60kg / cm2It is preferable that
[0019]
Furthermore, a substrate that achieves a water buoyancy rate of 95% or more on a weight basis for one month of the substrate is preferable, and as a result, the water buoyancy rate for one month of the photocatalyst carrying the photocatalyst on the surface of the substrate is based on the weight. It reaches 90% or more.
[0020]
Examples of the photocatalyst of the present invention or photocatalyst particles used in the production thereof include titanium oxide, zinc oxide, iron oxide, potassium titanate, tungsten oxide, and strontium titanate., SulfurAt least one of molybdenum fluoride and indium oxide can be used. Among these, titanium oxide, zinc oxide, iron oxide, strontium titanate and tungsten oxide are preferable, and titanium oxide is particularly preferable. Furthermore, what added the appropriate dopant to those photocatalyst particles can also be used.
[0021]
When the photocatalyst particles are titanium oxide, an anatase type is preferable, but a rutile type can also be used. The specific surface area is 20-500m2/ G is preferred, especially 100 to 400 m2/ G is more preferable. Further, the titanium oxide particle diameter is preferably 0.01 to 1 μm, more preferably 0.02 to 0.1 μm in terms of primary particle diameter, and a granulated product or a sintered body thereof may be used. When the particle size is increased by using a granulated product or a sintered body, photocatalyst particles can be found (exposed as active sites) from a film such as a silica film described later when the film thickness of the inorganic substance is relatively large depending on the application. Therefore, the photocatalytic activity appears effectively.
[0022]
Titanium oxide can also contain a metal oxide containing elements such as W, Sn, S, Mo, V, Mn and Zn in order to improve the catalytic activity.
[0023]
Similar to titanium oxide, the purity of other photocatalyst particles is not particularly defined, and if necessary, an appropriate impurity can be added for the purpose of adjusting the band gap.
[0024]
In addition, the photocatalyst of the present invention can contain a functional substance that adsorbs harmful substances such as activated carbon and zeolite, and can support and contain an antibacterial metal.
[0025]
In the photocatalyst of the present invention or the production thereof, silica, alumina, titanium oxide, or frit can be used as the inorganic substance as a binder for fixing the photocatalyst particles to the granulated artificial lightweight aggregate. The titanium oxide as an inorganic substance here also includes titanium peroxide. In the present invention, since the surface of the substrate has a glassy shell having physical properties similar to those of the binder, the adhesiveness by the binder is high, and particularly, the adhesiveness to silica is excellent. The surface structure of the vitreous shell having a dense structure with no gaps improves the adhesion and allows the photocatalyst particles to be included in the thin film on the substrate to be dispersed and fixed in a state having many active sites.
[0026]
When the binder is silica, the fixing property between the silica film containing the photocatalyst particles and the granulated artificial lightweight aggregate which is a substrate mainly composed of silica is the best. If the film thickness becomes too thick, it is useless for the photocatalytic effect, and the film strength tends to decrease, so that the film thickness is preferably 100 μm or less. The ratio of the photocatalyst particles in the silica film containing the photocatalyst particles is preferably 10 to 90% by weight, more preferably 20 to 85% by weight, and most preferably 40 to 80% by weight.
[0027]
The photocatalyst of the present invention has an excellent effect on removal of malodorous gases such as aldehydes and mercaptans, NOx, dioxins, etc., suppression of algae growth, and bactericidal properties due to the photocatalytic effect of ultraviolet irradiation, and has practical strength. The processability of the photocatalyst, the weather resistance, and the separation operability from the object to be processed are excellent.
[0028]
Regarding the selection of the substrate to be used, the granulated artificial lightweight aggregate of the present invention can have an apparent specific gravity larger or smaller than water depending on the amount of the binder and photocatalyst particles, for example, floating in water and / or It can be settling. That is, the specific gravity required for the application can be selected. A photocatalyst using a substrate set before and after the specific gravity of water can be widely used as it is for the purification of water, the sterilization of water, and the suppression of the growth and adhesion of algae, which will be described later.
[0029]
Typically, the photocatalyst of the present invention is obtained by dispersing the photocatalyst particles in an aqueous silica sol and water as an aqueous inorganic substance and adjusting the concentration of the photocatalyst particles to 5 to 30 wt%. It can be manufactured by immersing the substrate of the material to cause the paint to adhere to the surface of the substrate and then heat-treating it at 100 to 900 ° C.
[0030]
In the said manufacturing method, the photocatalyst particle density | concentration in a coating material is 5-30 wt%, Preferably it is 8-30 wt%. If it is less than 5 wt%, it is not preferable because it requires several times or more of dip-supporting treatment or coating operation in order to obtain a product with high photocatalytic ability, and the work becomes complicated, resulting in high costs. Further, even if the amount exceeds 30 wt%, the photocatalytic performance does not increase, and the viscosity of the coating is increased and the photocatalyst particles are excessively deposited on the surface of the substrate, which is useless, and the photocatalyst film thickness is excessively increased. This is not preferable because the film may be peeled off.
[0031]
Immersion of the granulated artificial lightweight aggregate in the paint can be realized by only one dipping process, so that the work is reduced, and as a result, a photocatalyst having high photocatalytic activity can be produced at low cost. The granulated artificial lightweight aggregate that has been soaked can be separated from the photocatalyst paint by means of a mesh, but in order to quickly remove the photocatalyst paint interposed between the particles of the aggregate, alcohol may be added to the photocatalyst paint. it can.
[0032]
In general, the heat treatment after adhesion of the paint is preferably 100 to 900 ° C, more preferably 100 to 800 ° C. This range is specified because when the temperature is lower than 100 ° C., it takes a long time to gel the aqueous silica sol and it is difficult to obtain film strength. When the temperature is higher than 900 ° C., the activity of the photocatalyst particles decreases.
[0033]
The aqueous silica sol to be used is a fine particle type having a particle size of 0.1 to 20 nm, more preferably 1 to 10 nm. When the particle size of the aqueous silica sol is large, the contact area with the photocatalyst particles is small, and therefore, the adhesive force is weakened. This silica sol needs to be a dehydrated aqueous silica sol. Aqueous silica sol, which is a basic sol with Na ions remaining, has a practical utility as a binder for fixing photocatalyst particles because Na ions are adsorbed on the photocatalyst particles and greatly attenuate the photocatalytic activity when used as a paint. Absent. The aqueous silica sol subjected to Na removal treatment can be obtained, for example, by removing Na from sodium silicate with an ion exchange resin.
[0034]
The bonding between the aqueous silica sol and the surface of the photocatalyst particles occurs at the contact point between the sol particles and the photocatalyst particles, but the aqueous silica sol has an appropriate size for the primary particle diameter of 0.01 to 1 μm considered to be preferable in the present invention. Therefore, there are many active sites not bonded to silica on the surface of the photocatalyst particles. For this reason, the photocatalytic ability is kept high.
[0035]
If the ratio (A / B) of the primary particle size (A) of the photocatalyst particles to the particle size (B) of the aqueous silica sol is in the range of 200 to 2, the number of aqueous silica sols adhering to the primary particles of the photocatalyst particles is It is in an optimum state in terms of the balance between the adhesive strength as a fixing film and the resolution. When (A / B) is greater than 200, the adhesive strength is strong, but the aqueous silica sol almost covers the active sites on the titanium oxide surface, so that resolution is hardly recognized. On the other hand, when (A / B) is smaller than 2, the resolution is high, but the adhesive force as a fixed film is extremely reduced.
[0036]
In addition, the ratio of the aqueous silica sol to the photocatalyst particles when preparing the paint is SiO210 to 900 wt% is preferable on the basis, more preferably 15 to 400 wt%, and most preferably 25 to 150 wt%. When the addition ratio of the aqueous silica sol is less than 10 wt%, the strength of the photocatalyst film is lowered, and when the addition ratio of the silica sol is more than 900 wt%, the titanium oxide concentration in the coating film is reduced. Since photocatalytic ability falls, it is not preferable.
[0037]
Further, even if the addition amount of the aqueous silica sol is increased within the above range, the photocatalytic ability is hardly lowered, and the strength of the coating film is improved almost in proportion to the addition amount. The excess aqueous silica sol after covering the first layer forms a network of siloxane bonds between the silica sol particles and contributes to the enhancement of the coating strength. Silica laminate made from aqueous silica sol has many nanometer-order pores, and the porosity of the coating is kept relatively high at 30-70%. It is considered easy and does not limit the rate of the photocatalytic reaction.
[0038]
An aqueous silica sol having a particle size smaller than 0.1 nm is not suitable as a binder for paints that require stability during long-term storage because it is close to the nature of an oligomer and easily gels. If the particle size is larger than 10 nm, the adhesive strength between the silica sols, the silica sol and the photocatalyst particles, and the adhesive layer between the silica sol and the substrate is weak, and a sufficient peel strength as a coating film cannot be obtained.
[0039]
For the purpose of strengthening the bonding of the silica sol, it is possible to improve the peel strength of the coating film by adding a low concentration acid, or a small amount of sodium silicate or sodium aluminate to the photocatalyst paint.
[0040]
Depending on the type of gas to be decomposed, the photocatalytic effect may be enhanced when an adsorbent other than photocatalyst particles is used in combination with the coating film. For example, when used for NOx purification, 1 to 30 wt% of zeolite, zinc oxide fine powder, titanium industry adsorbent TZ-100, etc. as the adsorbent is added to the titanium oxide, so that the NOx purification performance is greatly increased. Can be improved.
[0041]
The photocatalyst of the present invention can be produced not only by immersing the granulated artificial lightweight aggregate in the paint, but also by applying the paint.
[0042]
The photocatalyst particles may be fixed to the substrate by a known method using a suspension of amorphous photocatalyst particles or a low crystallinity photocatalyst particle suspension, not limited to a paint.
[0043]
The photocatalyst body of the present invention is placed in a bag-like or mesh-like storage container made of at least one selected from the group of fibers, resins, resin molded bodies, nonwoven fabrics, ceramics, metals, wood, and alloys, and contains the photocatalyst body. It can be.
[0044]
Here, a floating body may be put in the storage container, and the floating body may be at least one selected from the group of polystyrene foam, hollow filler, wood, and plastic.
[0045]
Furthermore, according to the present invention, harmful gas is allowed to pass through the above-mentioned photocatalyst body or the above-mentioned photocatalyst body housing, and the container or the housing is irradiated with light containing ultraviolet rays. It can be disassembled and removed.
[0046]
The harmful gas here includes aldehyde, mercaptan, ammonia, NOx, dioxin and the like.
[0047]
The photocatalyst can be used as it is in an appropriate place such as a park or a roadside tree.
[0048]
Further, in order to decompose and remove harmful gases efficiently and inexpensively, it is also possible to use a photocatalyst in a column. That is, the photocatalyst is placed in a column made of a material that transmits ultraviolet rays, harmful gases are forced or allowed to pass through them, and the harmful gases are decomposed and removed by irradiating a lamp containing sunlight or ultraviolet rays. Can do.
[0049]
It is also effective for removing dioxins discharged into the environment. Even if the primary generation of dioxins is sufficiently suppressed in combustion, secondary generation of dioxins occurs when the exhaust gas comes into contact with unburned matter or catalytic dust in the temperature range of 200 to 600 ° C. It is said that. The photocatalyst of the present invention can be used to remove the primary and secondary dioxins discharged into the environment from the exhaust gas side. For example, there is a method in which a column in which a photocatalyst is packed in a chimney of an incinerator is attached in one or more stages. If it is a column that transmits ultraviolet light, it can be decomposed simultaneously with adsorption by using sunlight, but if the column is easily removed, the adsorption column can be removed from the chimney and placed in another location. By irradiating with sunlight or an ultraviolet lamp, the adsorbed material can be decomposed. Moreover, this thing may be used repeatedly.
[0050]
Further, the photocatalyst body can be used in a frame made of a material that transmits ultraviolet rays. In this case, it is easy to carry and has features that it is easy to install and replace the photocatalyst.
[0051]
Further, the harmful gas can be decomposed and removed in the same manner even when the photocatalyst housing material is used.
[0052]
Furthermore, according to the present invention, water is passed through the photocatalyst body or the photocatalyst body housing article whose specific gravity is adjusted so as to float and / or settle in water, and light containing ultraviolet rays is irradiated. Water can be purified.
[0053]
Water as used herein includes factory wastewater, mining wastewater, industrial water, agricultural water, drinking water, lakes, river water, seawater, and the like. In purifying water using the photocatalyst of the present invention in the existing lake shore, river shore, coast, water channel, water tank, filter, sewer, or aquatic life, contact with these waters The photocatalyst is placed in a place where the photocatalyst is available, or the photocatalyst is put into water. Next, the arranged photocatalyst body is irradiated with light containing ultraviolet rays to purify water.
[0054]
Examples of the light containing ultraviolet rays include light from sunlight, fluorescent lamps, black lamps, xenon flash lamps, mercury lamps, and the like. Among these, in particular, light containing ultraviolet rays of 300 to 400 nm is preferable. The irradiation amount and irradiation time of light containing ultraviolet rays can be appropriately set depending on the degree of contamination of sewage. The method of irradiating the photocatalyst with light containing ultraviolet rays can be selected as appropriate.For example, when irradiating from the upper surface of the water surface, irradiating with a light source installed in the sewage, or purifying the sewage in the aquarium It is also possible to irradiate from the side surface of the water tank. Further, when the photocatalyst body of the present invention is disposed in the above-mentioned place where it can come into contact with sewage, and then irradiated with light containing ultraviolet rays, the sewage can be purified by the photocatalytic function of the photocatalyst body at the irradiated part, and At locations in the same reaction system that are not exposed to light containing ultraviolet light, microorganisms that have a water purification function generated in the reaction system adhere to the substrate, or microorganisms that have a water purification function in advance adhere to the photocatalyst. By purifying, the purification by the microorganism can be performed.
[0055]
Speaking of the target treated substances in the sewage purification method, organic waste such as free chlorine and trihalomethane remaining in the water can be decomposed and removed, and mining wastewater whose regulations have been strengthened by the revision of the Water Pollution Control Law. It can also be used to remove selenium contained therein.
[0056]
In the latter case, a method of using a photocatalyst body in mining wastewater and utilizing sunlight, a method of putting the photocatalyst body of the present invention in a column, passing the mining wastewater into the column, and applying an ultraviolet-containing irradiation lamp, etc. The hexavalent selenium is recovered by reducing it to tetravalent or zero-valent.
[0057]
Further, as an application of the method for purifying sewage using the photocatalyst body of the present invention, the harmful gas can be decomposed by immersing the pipe in the water into which the photocatalyst body is charged and allowing the harmful gas to pass through and bubbling.
[0058]
Furthermore, in order to improve the irradiation efficiency of light containing ultraviolet rays to the photocatalyst, the equipment is equipped with a light reflector, the inner wall surface of the container is mirror finished, or a mirror or similar is installed on the inner wall surface of the container You can also do it.
[0059]
For example, when purifying water using the photocatalyst of the present invention, a net or the like can be provided at the outlet of water to prevent the photocatalyst from flowing out, but the photocatalyst is placed in the storage container larger than the outlet diameter. If it is used as a photocatalyst storage material, outflow can be prevented and recovery can be facilitated.
[0060]
Moreover, when it is desired to use the photocatalyst body storage article suspended in water, a floating body may be put in the storage container. As the floating body, polystyrene foam, hollow filler, wood, plastics and the like can be used. On the contrary, when you want to submerge and fix it, or when you want to avoid movement by wind etc. when you place it on a road or roadside tree etc., you can fix it with rope, wire, adhesive etc. if possible, You may put wood, a stone, and a metal lump as a fixing material in a storage container.
[0061]
Furthermore, according to the present invention, it is possible to suppress the growth and adhesion of algae by using the above-mentioned photocatalyst body or the above-mentioned photocatalyst body storage article whose specific gravity is adjusted so that it floats and / or settles in water.
[0062]
Place the photocatalyst or the photocatalyst in a water tank, filter, sewer, reservoir, etc. in an environment where algae is likely to be generated or has already occurred, or simply put it in water And place it. Next, it is possible to irradiate the photocatalyst that has been placed or the photocatalyst containing material with ultraviolet light to suppress the growth and adhesion of algae. Can use sunlight more actively than indoors, so it is not necessary to use artificial lights.
[0063]
As described above, the algae preventive agent of the present invention is effective for the growth and adhesion of algae only by being thrown into water, and it is not necessary to install a mechanical device. Therefore, it can be used at low cost and easily.
[0064]
In any application, in addition to the photocatalyst in the storage container, as a photocatalytic effect auxiliary agent, harmful substance adsorbents such as activated carbon and zeolite, and these granulated and molded products, antibacterial substances and granulated products thereof, Appropriate amount of molding can be put at the same time.
[0065]
In addition, the photocatalyst body can be used by being fixed to the surface of a structure made of cement or the like, and the photocatalyst body itself is processed into a plate shape, a cylindrical shape, or the like using an adhesive. Can also be used.
[0066]
Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are merely examples, and the scope of the present invention is not limited thereto.
[0067]
【Example】
Granulated artificial lightweight aggregate (A) and method for producing granulated artificial lightweight aggregate (B)
Shirasu was granulated using water glass to obtain a substantially spherical granulated product. After curing for 1 week at room temperature, Li2O-Na2O-B2OThree-Al2OThree-P2OFiveThe frit having the composition was evenly adhered to the surface of the granulated powder and fired at about 900 ° C. using a kiln to obtain a granulated product covered with a glassy shell. The baked granulated material was screened to obtain a granulated artificial lightweight aggregate (A) having an average particle diameter of 15 mm and a granulated artificial lightweight aggregate (B) having an average particle diameter of 3 mm. Note that (A) has an absolutely dry density of 0.78 and a grain strength of 46 kg / cm.2The water floating rate for one month is 98%, and (B) is 0.51, 31 kg / cm in order.299%.
[0068]
Granulated artificial lightweight aggregate (C)
A commercially available Himelite made of Ehime Crushed Stone Co., Ltd. having an average particle diameter of 15 mm, which is a kind of granulated artificial lightweight aggregate covered with glassy shell, was used. This has an absolute dry density of 0.46 and a grain strength of 55 kg / cm.2The water floating rate for one month was 100%.
[0069]
Shirasu balloon agglomerate manufacturing method
Shirasu balloons were agglomerated using water glass and fired at about 900 ° C. using a kiln. The fired product was screened using a sieve to obtain a shirasu balloon agglomerate having an average particle size of about 15 mm.
[0070]
Example 1
Titanium oxide as photocatalyst particles (anatase type specific surface area 340m2/ G) 12 g, aqueous silica sol as a binder (particle size 5 nm, primary particle size of titanium dioxide / silica sol particle size = 4) 23.4 g, 12.6 g of pure water together with 60 g of 3 mm glass beads into a 120 ml glass bottle The resulting mixture was dispersed and mixed for 30 minutes with a paint conditioner manufactured by Red Devil to obtain a paint containing silica sol. The photocatalyst particle concentration in the paint is 25 wt%.
[0071]
Further, the granulated artificial lightweight aggregate (A) having an average particle size of 15 mm was used as a base, immersed in the paint, and the granulated artificial lightweight aggregate to which the paint and photocatalyst particles were fixed was separated by a sieve. After air-drying all day and night, the silica film containing photocatalyst particles was fixed to the substrate by baking at 110 ° C. A photocatalyst was obtained by heat treatment at 700 ° C. for 1 hour.
[0072]
Example 2
In Example 1, the same procedure was performed except that a granulated artificial lightweight aggregate (B) having an average particle diameter of 3 mm was used as the substrate.
[0073]
Example 3
In Example 1, the same procedure was performed except that the granulated artificial lightweight aggregate (C) was used as the substrate.
[0074]
Example 4
40 g of the sample of Example 1 was placed in a 10 cm × 10 cm × 2 cm earthenware mesh container to form a photocatalyst storage.
[0075]
[Comparative example]
Comparative Example 1
Only the granulated artificial lightweight aggregate (A) was used as a sample.
[0076]
Comparative Example 2
Only the granulated artificial lightweight aggregate (C) was used as a sample.
[0077]
Comparative Example 3
The sample of Comparative Example 1 was placed in a glass mesh container to make a stored item.
[0078]
Comparative Example 4
The same procedure was performed except that the amount of pure water at the time of preparing the coating material of Example 1 was 350 g, the amount of glass beads was 250 g (the photocatalyst particle concentration was lower than the desired concentration), and a 500 ml bottle was used.
[0079]
Comparative Example 5
The same procedure was performed except that a coating material in which the titanium oxide of Example 1 was dispersed in an acrylic-melamine resin (not a coating material in water) was applied to the substrate.
[0080]
Comparative Example 6
In Example 1, the same procedure was used except that the Shirasu balloon agglomerate having an average particle size of about 15 mm (not coated with a glass shell membrane) was used as the substrate, and the number of immersions in the paint was set to two. I went.
[0081]
Test example
1. Peel test
After observing the surface of the sample using scanning electron microscope observation and confirming that the photocatalyst particles are immobilized on the photocatalyst body, the photocatalyst body is placed in water and subjected to ultrasonic waves for 10 minutes. The water permeability after separation was measured. A transmittance of 95% or more was rated as ◯, and a transmittance of less than 95% was rated as ×.
[0082]
2. Weather resistance test
Using a Deuga panel light control weather meter manufactured by Suga Test Instruments Co., Ltd. for the photocatalyst, after 500 hours of ultraviolet irradiation, the change in the color tone of the photocatalyst was examined, and according to the peel test conditions described in 1, A peel test was performed to measure the transmittance. A case where no discoloration was visually observed and the transmittance in the peel test was 95% or more was evaluated as ◯, and a case where discoloration was observed or the transmittance in the peel test was less than 95% was evaluated as x.
[0083]
3. Pigment degradation test
Organic dye Orange 1 was dissolved in pure water to prepare a solution having an orange 1 concentration of 10 ppm. After placing 8 samples in a 50 ml beaker containing 25 ml of 10 ppm orange 1 solution and 1 rotor, the sample was gently stirred using a magnetic stirrer and stirring was continued until the end of the test. Absorbance A at 475 nm of a solution obtained by collecting 5 ml of water 30 minutes after the start of stirring and filtering through a 0.45 μm disk filter.t0Was measured. Continue UV irradiation for 1 hour (black light, UV intensity 2.8mW / cm2475 nm absorbance A of the solution filtered through a 0.45 μm disk filtert1Was measured. The pigment decomposition rate was calculated based on the following formula.
Decomposition rate = {(At0-At1) / At0} × 100
* Absorbance measurement: JASCO spectrophotometer UBEST50 type
[0084]
4). NOx purification test #Test method, test equipment, and test conditions are described below.
[0085]
<Test method>
1. Two samples for evaluation were placed in both petri dish type reaction vessels connected in series.
2. The NOx gas from the cylinder was mixed with air and allowed to flow through the bypass, and stabilized with a NOx concentration of 200 ppb and an air flow rate of 1 L / min.
3. 30 minutes after flowing the gas into the reaction vessel, UV intensity 0.1 mW / cm2Irradiation was started. The NOx concentration (Vint) immediately before irradiation with ultraviolet rays was measured.
4). The NOx concentration (V30) 30 minutes after the start of ultraviolet irradiation was measured.
The NOx purification rate was defined as follows.
NOx purification rate (%) = {(Vint−V30) / Vint} × 100
[0086]
<Test equipment>
NOx measuring device: Meter Service Co., Ltd. ML9841A
Reaction vessel: Vidro Chemical Petri dish type photoreaction vessel (inner diameter 156 mm, depth 32 mm) A glass lid was sandwiched with a Teflon (registered trademark) ring, fixed to the main body with a bolt, and gas was circulated through the side glass tube. .
Raw gas: NO / N2 0.1% gas cylinder
Flow rate adjustment: Thermal mass flow controller manufactured by Coflock Co., Ltd.
Piping: A Teflon (registered trademark) pipe was used.
[0087]
<Test conditions>
NOx concentration: about 200ppb
Gas flow rate: 1 L / min.
Sample for evaluation: 40 g of a sample was put in a paper frame of 10 cm × 10 cm × 1 cm.
UV intensity: 0.1 mW / cm2
Measurement temperature: 20 ° C
Humidity: Air was dried with silica gel. (About 60% at room temperature)
[0088]
5. Algae test
500 x 100 ml of blue-green algae (filamentous algae anabena) collected from a reservoir and 40 g of a test sample, or a photocatalyst container containing 40 g of a test sample in a mesh storage container, each 120 x 150 x 70 mmThreeIn a plastic container and left outside in the summer for two months. The antibacterial metal particles and the volcanic eruption foamed particle moldings (blanks) to which the photocatalyst particles are not fixed were simultaneously left to observe the algae propagation state and the algae adhesion state to the container. The case where the amount of propagation was small compared to the blank or the case where the adhesion of algae to the inner wall of the container was not recognized as ◯, and the case where the increase of the reproduction amount or the attachment of the algae to the inner wall of the container was recognized as ×.
[0089]
6). Antibacterial test
Place 20 test samples or a photocatalyst container containing 20 test samples in a reticulated storage container into 50 ml of ion-exchanged water with E. coli solution added, store at 30 ° C, and irradiate with a 10W fluorescent lamp. The number of viable bacteria after 6 hours was measured. Initial bacterial count is 10FourThe number of viable bacteria after 6 hours was measured, and the kill rate was calculated based on the following formula.
Death rate (%) = {(initial bacterial count−viable bacterial count after 6 hours) / initial bacterial count} × 100
[0090]
7. Grain strength
Using a compression tester, the breaking strength of about 10 mm diameter grains was measured. The fracture strength value per unit area was calculated, and the average value of 20 grains was defined as the grain strength.
[0091]
8). Absolute dry density
Iron cylinder 2 liters (regular capacity VcmThree) Was filled with a dry sample according to the jigging method, and the weight of the filled sample (Wg) at this time was measured. The absolute dry density was calculated | required based on the following formula | equation.
Absolute dry density (g / cmThree) = W / {V × (m / 100)} m: Actual rate (%)
[0092]
The results are shown in Table 1.
[Table 1]
From the results shown in Table 1, it was found that the samples of the examples were superior in pigment decomposition rate and NOx purification rate than the comparative examples, and suppressed adhesion of algae.
[0094]
【The invention's effect】
The present invention is based on a granulated artificial lightweight aggregate with a specific shape coated with a glassy shell having a particle size and the photocatalyst particles are fixed on the surface thereof. Have sufficient strength to withstand.
Claims (12)
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| JP4563689B2 (en) * | 2004-01-19 | 2010-10-13 | 独立行政法人産業技術総合研究所 | Photocatalyst and method for producing the same |
| JP2005230758A (en) * | 2004-02-23 | 2005-09-02 | Okaya Electric Ind Co Ltd | Photocatalyst carrier |
| WO2005115614A1 (en) * | 2004-05-26 | 2005-12-08 | Ecology Souzo Kenkyusho Co., Ltd. | Decomposer/purifier using photocatalyst, method for producing same, and decomposing/purifying method using same |
| JP2007061745A (en) * | 2005-08-31 | 2007-03-15 | Dainippon Printing Co Ltd | Surface-treating method |
| JP4625742B2 (en) * | 2005-09-26 | 2011-02-02 | 太平洋セメント株式会社 | Method for producing photocatalyst body |
| CN112573657B (en) * | 2020-11-30 | 2022-08-19 | 中天华诺建设有限公司 | Filler for ammonia nitrogen sewage treatment |
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