JP3803701B2 - Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water - Google Patents
Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water Download PDFInfo
- Publication number
- JP3803701B2 JP3803701B2 JP17240196A JP17240196A JP3803701B2 JP 3803701 B2 JP3803701 B2 JP 3803701B2 JP 17240196 A JP17240196 A JP 17240196A JP 17240196 A JP17240196 A JP 17240196A JP 3803701 B2 JP3803701 B2 JP 3803701B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- organic halogen
- titanium oxide
- catalyst
- photocatalyst
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 42
- 150000002896 organic halogen compounds Chemical class 0.000 title claims description 40
- 238000000034 method Methods 0.000 title claims description 33
- 239000011941 photocatalyst Substances 0.000 title claims description 24
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 50
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 40
- 239000003054 catalyst Substances 0.000 claims description 38
- 230000001678 irradiating effect Effects 0.000 claims description 4
- 239000010936 titanium Substances 0.000 description 11
- 239000000843 powder Substances 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000003463 adsorbent Substances 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- UKGZHELIUYCPTO-UHFFFAOYSA-N dicesium;oxygen(2-);titanium(4+) Chemical compound [O-2].[O-2].[O-2].[Ti+4].[Cs+].[Cs+] UKGZHELIUYCPTO-UHFFFAOYSA-N 0.000 description 6
- 239000007800 oxidant agent Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- VDZOOKBUILJEDG-UHFFFAOYSA-M tetrabutylammonium hydroxide Chemical compound [OH-].CCCC[N+](CCCC)(CCCC)CCCC VDZOOKBUILJEDG-UHFFFAOYSA-M 0.000 description 6
- -1 amine alkylamine Chemical class 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 244000005700 microbiome Species 0.000 description 5
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical class O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000010865 sewage Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 150000001412 amines Chemical class 0.000 description 3
- FJDQFPXHSGXQBY-UHFFFAOYSA-L caesium carbonate Chemical compound [Cs+].[Cs+].[O-]C([O-])=O FJDQFPXHSGXQBY-UHFFFAOYSA-L 0.000 description 3
- 229910000024 caesium carbonate Inorganic materials 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000003673 groundwater Substances 0.000 description 3
- 239000010842 industrial wastewater Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000006864 oxidative decomposition reaction Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 238000006303 photolysis reaction Methods 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- ISPYQTSUDJAMAB-UHFFFAOYSA-N 2-chlorophenol Chemical compound OC1=CC=CC=C1Cl ISPYQTSUDJAMAB-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 150000003973 alkyl amines Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000011260 aqueous acid Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229960001701 chloroform Drugs 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 239000004434 industrial solvent Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000015843 photosynthesis, light reaction Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 150000003071 polychlorinated biphenyls Chemical group 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000004083 survival effect Effects 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Images
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
Description
【０００１】
【発明の属する技術分野】
本発明は、例えば、地下水、河川水、上下水道水、工業廃水などに含まれるトリクロロメタン等の有機ハロゲン化合物を除去することを目的とした酸化チタン光触媒および水中に含まれる有機ハロゲン化合物の除去方法に関するものである。
【０００２】
【従来の技術】
水道水の塩素消毒により発生するトリハロメタンや、工業用溶媒として用いられるトリクロロエチレン等の有機ハロゲン化合物は発ガン性を有するため、地下水、河川水、上下水道水、工業廃水などに含まれる有機ハロゲン化合物を水中から除去する必要がある。
【０００３】
従来、水中に含まれる有機ハロゲン化合物を除去する方法としては、触媒による方法、微生物による方法、酸化剤による方法、紫外線による光分解法および吸着剤による方法などがある。
【０００４】
触媒による方法は、とくにＰｔやＰｄなどの貴金属元素を担持したアルミナやシリカなどの触媒を使用して、加熱した触媒層に水分をストリッピングにより気化させたのちのガスなどを導入して、接触酸化分解する方法が一般的である。
【０００５】
微生物による方法は、上下水道などでは、微生物により有機ハロゲン化合物を代謝分解して除去する方法である。
【０００６】
酸化剤による方法は、オゾンや過酸化水素などの酸化剤を用いて水中の有機ハロゲン化合物を酸化分解して除去する方法である。
【０００７】
光分解法としては、波長が２５０ｎｍ以下の紫外線を照射し、有機ハロゲン化合物を光分解する方法である。
【０００８】
吸着剤による方法は、吸着剤の吸着力を利用して有機ハロゲン化合物を吸着剤に吸着して回収する方法である。
【０００９】
また近年になり、光触媒を取り入れたシステムとして、半導体物質の存在下に光照射により廃水処理をする方法が提案されている（例えば、特開平５−３３７４６９号）。
【００１０】
【発明が解決しようとする課題】
しかし、触媒による方法では、一度水分を気化させる必要があることから、おのずと処理量が小さく、十分な処理量を確保するためには、水処理装置が大掛かりになる点に問題があった。
【００１１】
微生物や酸化剤を使用する方法では有機ハロゲン化合物の種類により分解できる物質とできない物質があり、完全な除去ができず、また、微生物の生存に適した環境を維持することが困難であり、他の方法との組み合わせが必要で、必然的に処理装置が大型化するなどの問題点があった。
【００１２】
波長が２５０ｎｍ以下の紫外線を照射して、光分解反応により処理する方法では、使用する紫外線が波長が極めて短いために、処理に際し、多量のエネルギーが必要であり、また、２５０ｎｍ以下の紫外線は人体に有害であり、取扱いに注意が必要であった。
【００１３】
吸着剤を使用する場合は吸着剤の再生処理が必要であり、また、あくまで有機ハロゲン化合物を物理的に吸着させるだけであり、本質的に有機ハロゲン化合物を分解除去できないという問題点があった。
【００１４】
光触媒を用いる方法では、光触媒の酸化分解力が弱いために有機ハロゲン化合物を含む廃水をあらかじめオゾンや過酸化水素などの酸化剤と接触させる前処理過程が必要であり、迅速な完全分解処理が困難であった。
【００１５】
なお、半導体光触媒としては酸化チタンが知られている（A.Fujishima,K.Honda,Nature,238,37(1972)）。酸化チタンの形状としては粉末状、薄膜状などが用いられている（藤島ら，用水と廃水，36,(2),6-11(1994)）。しかし、従来の酸化チタンでは酸化力が十分に強くないために上記のように酸化剤による前処理過程が必要であるなどの問題点があった。
【００１６】
本発明が解決しようとする課題は、上記の従来法の問題点を解消し、例えば地下水、河川水、上下水道水、工業廃水などに含まれる有機ハロゲン化合物を微量の光エネルギーにより効率よく除去する水中に含まれる有機ハロゲン化合物除去用の光触媒および有機ハロゲン化合物の除去方法を提供するものである。
【００１７】
【課題を解決するための手段】
本発明者らは、上記課題を解決すべく鋭意研究を重ねた結果、酸化チタンを触媒とし、その触媒形状が薄片状である酸化チタンが、水中に含まれる有機ハロゲン化合物を微量の光によるエネルギーで除去する水中有機ハロゲン化合物除去能力が高く、耐久性にも優れるものであることを見出し、本発明を完成するに至った。
【００１８】
すなわち、本発明は、触媒形状が薄片状である酸化チタンからなることを特徴とする水中に含まれる有機ハロゲン化合物除去用の光触媒および薄触媒形状が薄片状である酸化チタンからなる光触媒の存在下、２５０〜４００ｎｍの光を照射することを特徴とする水中に含まれる有機ハロゲン化合物の除去方法に関するものである。
【００１９】
【発明の実施の形態】
本発明の水中での有機ハロゲン化合物除去用の光触媒は、触媒形状が薄片状である酸化チタンでなければならない。触媒形状が薄片上である場合、触媒がきれいに分散して、水中に含まれる有機ハロゲン化合物を除去する。薄片状とは厚さが１ｎｍから１０μｍ、好ましくは１ｎｍ〜１００ｎｍであり、長さが１０ｎｍから５００μｍの薄片である。酸化チタン光触媒の厚さと長さが上記範囲外の場合は、水中に含まれる有機ハロゲン化合物の除去率が低く好ましくない。
【００２０】
この薄片状の酸化チタン触媒の結晶相はアナターゼ型でもルチル型、あるいは双方の混合相であっても構わないが、触媒の形状が薄片状であることが必須である。
【００２１】
触媒形状が薄片状である酸化チタンは種々の方法により合成できることが知られているが、本発明の光触媒を構成する薄片状の酸化チタンの製造方法は特に限定されるものではない。
【００２２】
例えば、層状構造を有するチタン酸化物であるＮａ2Ｔｉ3Ｏ7やＫ2Ｔｉ4Ｏ9や層・トンネル互層物質であるＫ6Ｔｉ16Ｏ35などを固相法や液相法またはアルコキシド法などにより合成する。これらの層状または層・トンネル互層物質を塩酸などの酸水溶液中または溶融塩中でイオン交換を行うことにより酸型の層状または層・トンネル互層のチタン酸化物を得る。この酸型の層状または層・トンネル互層のチタン酸化物とテンプレート剤であるアルキルアミンとを溶液中で混合し、ホスト層を１枚１枚のレベルまで剥離分散する。得られたゾル溶液を乾燥後、酸化雰囲気中で４００℃から１２００℃までの温度で焼成することにより、酸化チタンが結晶化し、薄片状の酸化チタンを得ることができる。焼成温度が４００℃より低いと層間のアルキルアミンが分解除去することができず、薄片状の酸化チタンが得ることができない。また、焼成温度が１２００℃より高いと一度生成した薄片状の酸化チタンがさらに反応、焼結してしまい、薄片の状態を維持することができないので好ましくない。
【００２３】
また、この薄片状の酸化チタンにＰｔなどの金属やＣｕなどの金属酸化物を担持したり、混合したりして使用することもできる。
【００２４】
また、この触媒は薄片状の鱗片末として用いる他に、多孔質の触媒担体や石英ガラス管または石英ガラス基板上などにこの薄片状の酸化チタンをコーティングして酸化チタン膜として用いることができる。膜として用いる場合は、薄片状の酸化チタンを分散させた水溶液または非水溶液に多孔質の触媒担体や石英ガラス管または石英ガラス基板を漬けた後、焼成する方法などが取られる。
【００２５】
本発明の光触媒を用いて、水中に含まれる有機ハロゲン化合物を除去するには、触媒形状が薄片状の酸化チタンからなる光触媒の存在下、２５０〜４００ｎｍの光を照射し、有機ハロゲン化合物を含む水と本発明の薄片状の酸化チタン光触媒を接触させることにより行うことができる。
【００２６】
水中の有機ハロゲン化合物を除去するために照射される２５０〜４００ｎｍの光としては、太陽光や３６０ｎｍ付近の長い紫外線が挙げられるが、３６０ｎｍ付近の紫外線が酸化チタンの光の吸収率が急激に増加するので好ましい。
【００２７】
本発明が対象とする有機ハロゲン化合物は例えば、卜リハロメタン、トリクロロエチレン、テトラクロロエチレン、クロロベンゼン、クロロフェノール、ポリ塩化ビフェニールなどである。有機ハロゲン化合物の濃度については特に制限はないが、水中での含有量が１００ｐｐｍ以下の領域で本発明の光触媒を使用することが実用上好ましい。
【００２８】
【実施例】
以下、本発明を実施例および比較例により、更に詳細に説明するが、本発明はこれら実施例に限定されるものではない。
【００２９】
実施例１
炭酸セシウム（Ｃｓ2ＣＯ3）と酸化チタン（ＴｉＯ2）を１：５．３のモル比に混合し、８００℃で２４時間焼成して、チタン酸セシウム（ＣｓxＴｉ2-x/4Ｏ4）を合成した。チタン酸セシウムの粉末を１規定の塩酸水溶液中で３６時間攪拌後、ろ過、風乾して層状酸化チタン酸（ＨxＴｉ2-x/4Ｏ4・ｎＨ2Ｏ）を得た。このチタン酸粉末１ｇをテトラブチルアンモニウム水酸化物水溶液２００ｃｍ3に加えシェーカーで１５０ｒｐｍ程度の振盪を行うことによリチタニアゾルを得た。このゾルを冷凍庫中（−３０℃）で凍結せしめ、真空凍結乾燥を行うと綿状のゲルが生成した。次に得られたゲルを５００℃で焼成することにより層状チタン酸の層間に存在した水やアミンが脱離し、層状構造が崩壊し、薄片状（平均厚さ１００ｎｍ、平均長さ１００μｍ）の酸化チタンを得た。
【００３０】
この触媒のＸ線回折結果を図１に、また、走査電子顕微鏡（ＳＥＭ）の測定結果を図２に示す。Ｘ線回折結果からこの触媒の結晶系はアナターゼ型であった。触媒活性評価試験はバッチ式の反応装置を用いて行った。１０ｐｐｍの卜リクロロエチレンを含んだ蒸留水１リットル中に触媒を１ｇ入れ、攪拌しながら１５Ｗ、３６０ｎｍの紫外線を照射し、一定時間ごとの水溶液中の卜リクロロエチレンの濃度を測定した。ただし、水中での有機ハロゲン化合物除去活性は次式で示されるように有機ハロゲン化合物除去率として算出した。
【００３１】
有機ハロゲン化合物除去率(%)＝［（ＴＣＥ0−ＴＣＥt）／ＴＣＥ0］×１００
ここでＴＣＥ0：卜リクロロエチレンの初期濃度（ｐｐｍ）
ＴＣＥt：一定時間光照射後の卜リクロロエチレン濃度（ｐｐｍ）
トリクロロエチレンの濃度はＰＩＤガスクロマトグラフにより測定した。
【００３２】
測定結果を表１に示す。
【００３３】
実施例２
炭酸セシウム（Ｃｓ2ＣＯ3）と酸化チタン（ＴｉＯ2）を１：５．３のモル比に混合し、８００℃で２４時間焼成することにより、チタン酸セシウム（ＣｓxＴｉ2-x/4Ｏ4）を合成した。チタン酸セシウムの粉末を１規定の塩酸水溶液中で３６時間攪拌後、ろ過、風乾して層状酸化チタン酸（ＨxＴｉ2-x/4Ｏ4・ｎＨ2Ｏ）を得た。このチタン酸粉末１ｇをテトラブチルアンモニウム水酸化物水溶液２００ｃｍ3に加えシェーカーで１５０ｒｐｍ程度の振盪を行うことによリチタニアゾルを得た。このゾルを冷凍庫中（−３０℃）で凍結せしめ、真空凍結乾燥を行うと綿状のゲルが生成した。次に得られたゲルを７００℃で焼成することにより層状チタン酸の層間に存在した水やアミンが脱離し、層状構造が崩壊し、薄片状（平均厚さ１００ｎｍ、平均長さ１００μｍ）の酸化チタンを得た。
【００３４】
この触媒のＸ線回折結果を図１に、また走査電子顕微鏡（ＳＥＭ）の測定結果を図２に示す。Ｘ線回折結果からこの触媒はアナターゼとルチル型の混相であった。
【００３５】
触媒の活性の評価は実施例１に隼拠して行った。結果を表１に示す。
【００３６】
実施例３
炭酸セシウム（Ｃｓ2ＣＯ3）と酸化チタン（ＴｉＯ2）を１：５．３のモル比に混合し、８００℃で２４時間焼成することにより、チタン酸セシウム（ＣｓXＴｉ2-X/4Ｏ4）を合成した。チタン酸セシウムの粉末を１規定の塩酸水溶液中で３６時間攪拌後、ろ過、風乾して層状酸化チタン酸（ＨxＴｉ2-x/4Ｏ4・ｎＨ2Ｏ）を得た。このチタン酸粉末１ｇをテトラブチルアンモニウム水酸化物水溶液２００ｃｍ3に加えシェーカーで１５０ｒｐｍ程度の振握を行うことによリチタニアゾルを得る。このゾルを冷凍庫中（−３０℃）で凍結せしめ、真空凍結乾燥を行うと綿状のゲルが生成した。次に得られたゲルを９００℃で焼成することにより層状チタン酸の層間に存在した水やアミンが脱離し、層状構造が崩壊し、薄片状（平均厚さ１００ｎｍ、平均長さ１００μｍ）の酸化チタンを得た。
【００３７】
この触媒のＸ線回折結果を図１に、また走査電子顕微鏡（ＳＥＭ）の測定結果を図２に示す。Ｘ線回折結果からこの触媒の結晶系はルチル型であった。
【００３８】
触媒の活性の評価は実施例１に準拠して行った。結果を表１に示す。
【００３９】
比較例１
ブランクテストとして触媒を何も使用しないで、実施例１に準拠して活性評価を行い、３６０ｎｍの紫外線の照射だけでは卜リクロロエチレンがほとんど分解しないことを確認した。
【００４０】
比較例２
酸化チタンとして触媒学会参照触媒である酸化チタン、ＪＲＣ―ＴＩＯ−２を使用した。この触媒はアナターゼ型の結晶粉末で、比表面積は１８ｍ2／ｇであった。触媒の活性評価は実施例１に準拠して行った。結果を表１に示す。
【００４１】
比較例３
酸化チタンとして触媒学会参照触媒である酸化チタン、ＪＲＣ一ＴＩＯ―３を使用した。この触媒はルチル型の結晶粉末で、比表面積は４０ｍ2／ｇであった。触媒の活性評価は実施例１に準拠して行った。結果を表１に示す。
【００４２】
【表１】
表１に示した結果から明らかなように、実施例１〜３に示した本発明の薄片状の酸化チタン光触媒は、比較例２および３に示した従来の粉末状結晶の酸化チタン光触媒に比べて、水中に含まれる有機ハロゲン化合物の除去率が高いことが分かる。
【００４４】
【発明の効果】
本発明の酸化チタン光触媒は、従来の酸化チタンにない高い有機ハロゲン化合物除去率を示し、効率的に有機ハロゲン化合物の除去を行うことができるという効果が得られる。
【図面の簡単な説明】
【図１】本発明の光触媒のＸ線回折図。
【図２】本発明の光触媒の走査電子顕微鏡写真。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a titanium oxide photocatalyst for removing organic halogen compounds such as trichloromethane contained in, for example, groundwater, river water, water and sewage water, industrial wastewater, and the like, and a method for removing organic halogen compounds contained in water It is about.
[0002]
[Prior art]
Organic halogen compounds such as trihalomethane generated by chlorine disinfection of tap water and trichlorethylene used as industrial solvents are carcinogenic, so organic halogen compounds contained in groundwater, river water, water and sewage water, industrial wastewater, etc. Need to be removed from the water.
[0003]
Conventionally, methods for removing organic halogen compounds contained in water include a method using a catalyst, a method using a microorganism, a method using an oxidizing agent, a photodecomposition method using ultraviolet rays, and a method using an adsorbent.
[0004]
The catalyst method uses a catalyst such as alumina or silica carrying a precious metal element such as Pt or Pd, and introduces a gas after vaporizing water by stripping the heated catalyst layer. A method of oxidative decomposition is common.
[0005]
The method using microorganisms is a method in which organic halogen compounds are metabolized and removed by microorganisms in water and sewage systems.
[0006]
The method using an oxidizing agent is a method in which an organic halogen compound in water is removed by oxidative decomposition using an oxidizing agent such as ozone or hydrogen peroxide.
[0007]
The photolysis method is a method in which an organic halogen compound is photolyzed by irradiating with an ultraviolet ray having a wavelength of 250 nm or less.
[0008]
The method using an adsorbent is a method in which an organic halogen compound is adsorbed on an adsorbent and recovered using the adsorbing power of the adsorbent.
[0009]
Recently, as a system incorporating a photocatalyst, a method of treating wastewater by light irradiation in the presence of a semiconductor material has been proposed (for example, JP-A-5-337469).
[0010]
[Problems to be solved by the invention]
However, in the method using a catalyst, since it is necessary to vaporize the water once, there is a problem in that the amount of water treatment is naturally large in order to ensure a small amount of treatment and a sufficient amount of treatment.
[0011]
There are substances that can be decomposed and cannot be decomposed depending on the type of organohalogen compound in the method using microorganisms and oxidizing agents, and cannot be completely removed, and it is difficult to maintain an environment suitable for the survival of microorganisms. In combination with this method, there is a problem that the processing apparatus is inevitably enlarged.
[0012]
In the method of irradiating ultraviolet rays having a wavelength of 250 nm or less and treating by photolysis reaction, since the ultraviolet rays to be used are extremely short, a large amount of energy is required for the treatment, and ultraviolet rays having a wavelength of 250 nm or less It was harmful to handling, and handling was necessary.
[0013]
When the adsorbent is used, it is necessary to regenerate the adsorbent, and only the organic halogen compound is physically adsorbed, and the organic halogen compound cannot be essentially decomposed and removed.
[0014]
In the method using photocatalyst, since the oxidative decomposition ability of the photocatalyst is weak, a pretreatment process in which wastewater containing an organic halogen compound is contacted with an oxidizing agent such as ozone or hydrogen peroxide in advance is necessary, and rapid complete decomposition treatment is difficult. Met.
[0015]
In addition, titanium oxide is known as a semiconductor photocatalyst (A. Fujishima, K. Honda, Nature, 238, 37 (1972)). As the shape of titanium oxide, powder, thin film, etc. are used (Fujishima et al., Water and wastewater, 36, (2), 6-11 (1994)). However, the conventional titanium oxide has a problem that the oxidizing power is not sufficiently strong, so that a pretreatment process with an oxidizing agent is necessary as described above.
[0016]
The problem to be solved by the present invention is to solve the problems of the above-mentioned conventional methods, and efficiently remove organic halogen compounds contained in, for example, groundwater, river water, water and sewage water, industrial wastewater, etc. with a small amount of light energy. A photocatalyst for removing an organic halogen compound contained in water and a method for removing the organic halogen compound are provided.
[0017]
[Means for Solving the Problems]
As a result of intensive research to solve the above problems, the present inventors have made titanium oxide as a catalyst, and the titanium oxide that has a flake shape of the catalyst is capable of converting an organic halogen compound contained in water into a small amount of light energy. The present inventors have found that the organic halogen compound removal ability in water is high and the durability is excellent, and the present invention has been completed.
[0018]
That is, the present invention is the presence of a photocatalyst for removing an organic halogen compound contained in water and a photocatalyst comprising a titanium oxide having a thin flake shape, characterized by comprising a titanium oxide having a flake-like catalyst shape. The present invention relates to a method for removing an organic halogen compound contained in water, which is characterized by irradiating light of 250 to 400 nm.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The photocatalyst for removing an organic halogen compound in water of the present invention must be a titanium oxide having a flake-like catalyst shape. When the catalyst shape is on a flake, the catalyst is finely dispersed to remove organic halogen compounds contained in water. The flaky shape is a thin piece having a thickness of 1 nm to 10 μm, preferably 1 nm to 100 nm, and a length of 10 nm to 500 μm. When the thickness and length of the titanium oxide photocatalyst are outside the above ranges, the removal rate of the organic halogen compound contained in the water is low, which is not preferable.
[0020]
The crystal phase of the flaky titanium oxide catalyst may be anatase type, rutile type, or a mixed phase of both, but it is essential that the shape of the catalyst is flaky.
[0021]
Although it is known that titanium oxide having a flaky catalyst shape can be synthesized by various methods, the method for producing the flaky titanium oxide constituting the photocatalyst of the present invention is not particularly limited.
[0022]
For example, Na 2 Ti 3 O 7 and K 2 Ti 4 O 9 which are titanium oxides having a layered structure, and K 6 Ti 16 O 35 which is a layer / tunnel alternate layer material are used in a solid phase method, a liquid phase method or an alkoxide method. Synthesize by. These layered or layer-tunnel alternating layers are subjected to ion exchange in an aqueous acid solution such as hydrochloric acid or in a molten salt to obtain an acid-type layered or layer-tunnel alternating layer titanium oxide. The acid-type layered or layer-tunnel alternating layer titanium oxide and the template amine alkylamine are mixed in a solution, and the host layers are peeled and dispersed one by one. The obtained sol solution is dried and then baked at a temperature from 400 ° C. to 1200 ° C. in an oxidizing atmosphere, whereby the titanium oxide is crystallized, and a flaky titanium oxide can be obtained. If the firing temperature is lower than 400 ° C., the alkylamine between layers cannot be decomposed and removed, and flaky titanium oxide cannot be obtained. On the other hand, if the firing temperature is higher than 1200 ° C., the flaky titanium oxide once produced is further reacted and sintered, and the flake state cannot be maintained, which is not preferable.
[0023]
Further, the flaky titanium oxide can be used by supporting or mixing a metal such as Pt or a metal oxide such as Cu.
[0024]
In addition to using the catalyst as a flaky scale powder, the flaky titanium oxide can be coated on a porous catalyst carrier, a quartz glass tube or a quartz glass substrate, and used as a titanium oxide film. When used as a film, a porous catalyst carrier, a quartz glass tube or a quartz glass substrate is immersed in an aqueous solution or non-aqueous solution in which flaky titanium oxide is dispersed, and then fired.
[0025]
In order to remove an organic halogen compound contained in water using the photocatalyst of the present invention, the catalyst is irradiated with light of 250 to 400 nm in the presence of a photocatalyst composed of flaky titanium oxide, and contains an organic halogen compound. It can be performed by bringing water into contact with the flaky titanium oxide photocatalyst of the present invention.
[0026]
Examples of the 250 to 400 nm light irradiated to remove organic halogen compounds in water include sunlight and long ultraviolet light near 360 nm, but ultraviolet light near 360 nm rapidly increases the light absorption rate of titanium oxide. This is preferable.
[0027]
Examples of the organic halogen compound targeted by the present invention include trihalomethane, trichloroethylene, tetrachloroethylene, chlorobenzene, chlorophenol, and polychlorinated biphenyl. Although there is no restriction | limiting in particular about the density | concentration of an organic halogen compound, It is practically preferable to use the photocatalyst of this invention in the area | region whose content in water is 100 ppm or less.
[0028]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.
[0029]
Example 1
Cesium carbonate (Cs 2 CO 3 ) and titanium oxide (TiO 2 ) were mixed at a molar ratio of 1: 5.3, and calcined at 800 ° C. for 24 hours to obtain cesium titanate (Cs x Ti 2-x / 4 O 4 ) was synthesized. After stirring for 36 hours the powder in 1 N hydrochloric acid aqueous solution of cesium titanate, filtered to give the air-dried in a layered titanium oxide acid (H x Ti 2-x / 4 O 4 · nH 2 O). 1 g of this titanic acid powder was added to 200 cm 3 of an aqueous tetrabutylammonium hydroxide solution and shaken at about 150 rpm with a shaker to obtain a lithitania sol. When this sol was frozen in a freezer (−30 ° C.) and vacuum lyophilized, a cotton-like gel was formed. Next, by baking the obtained gel at 500 ° C., water and amine existing between the layers of the layered titanic acid are eliminated, the layered structure is destroyed, and flaky (average thickness 100 nm, average length 100 μm) oxidation Titanium was obtained.
[0030]
The X-ray diffraction result of this catalyst is shown in FIG. 1, and the measurement result of a scanning electron microscope (SEM) is shown in FIG. From the result of X-ray diffraction, the crystal system of this catalyst was anatase type. The catalytic activity evaluation test was conducted using a batch type reactor. 1 g of the catalyst was put in 1 liter of distilled water containing 10 ppm of polychlorethylene, and irradiated with 15 W and 360 nm ultraviolet light while stirring, and the concentration of polychlorethylene in the aqueous solution was measured at regular intervals. However, the organic halogen compound removal activity in water was calculated as the organic halogen compound removal rate as shown by the following formula.
[0031]
Organic halogen compound removal rate (%) = [(TCE 0 −TCE t ) / TCE 0 ] × 100
Where TCE 0 : initial concentration of trichlorethylene (ppm)
TCE t : Polychlorethylene concentration (ppm) after light irradiation for a certain time
The concentration of trichlorethylene was measured by a PID gas chromatograph.
[0032]
The measurement results are shown in Table 1.
[0033]
Example 2
Cesium carbonate (Cs 2 CO 3 ) and titanium oxide (TiO 2 ) were mixed at a molar ratio of 1: 5.3, and calcined at 800 ° C. for 24 hours, whereby cesium titanate (Cs x Ti 2-x / 4 O 4) was synthesized. After stirring for 36 hours the powder in 1 N hydrochloric acid aqueous solution of cesium titanate, filtered to give the air-dried in a layered titanium oxide acid (H x Ti 2-x / 4 O 4 · nH 2 O). 1 g of this titanic acid powder was added to 200 cm 3 of an aqueous tetrabutylammonium hydroxide solution and shaken at about 150 rpm with a shaker to obtain a lithitania sol. When this sol was frozen in a freezer (−30 ° C.) and vacuum lyophilized, a cotton-like gel was formed. Next, by baking the obtained gel at 700 ° C., water and amines existing between the layers of the layered titanic acid are eliminated, the layered structure is destroyed, and flaky (average thickness 100 nm, average length 100 μm) oxidation Titanium was obtained.
[0034]
The X-ray diffraction result of this catalyst is shown in FIG. 1, and the measurement result of a scanning electron microscope (SEM) is shown in FIG. From the X-ray diffraction results, this catalyst was a mixed phase of anatase and rutile type.
[0035]
The activity of the catalyst was evaluated based on Example 1. The results are shown in Table 1.
[0036]
Example 3
Cesium carbonate (Cs 2 CO 3 ) and titanium oxide (TiO 2 ) were mixed at a molar ratio of 1: 5.3 and baked at 800 ° C. for 24 hours, whereby cesium titanate (Cs X Ti 2-X / 4 O 4) was synthesized. After stirring for 36 hours the powder in 1 N hydrochloric acid aqueous solution of cesium titanate, filtered to give the air-dried in a layered titanium oxide acid (H x Ti 2-x / 4 O 4 · nH 2 O). 1 g of this titanic acid powder is added to 200 cm 3 of an aqueous tetrabutylammonium hydroxide solution and shaken at about 150 rpm with a shaker to obtain a lithitania sol. When this sol was frozen in a freezer (−30 ° C.) and vacuum lyophilized, a cotton-like gel was formed. Next, by baking the obtained gel at 900 ° C., water and amine existing between the layers of the layered titanate are eliminated, the layered structure is destroyed, and flaky (average thickness 100 nm, average length 100 μm) oxidation Titanium was obtained.
[0037]
The X-ray diffraction result of this catalyst is shown in FIG. 1, and the measurement result of a scanning electron microscope (SEM) is shown in FIG. From the X-ray diffraction results, the crystal system of this catalyst was rutile type.
[0038]
The activity of the catalyst was evaluated according to Example 1. The results are shown in Table 1.
[0039]
Comparative Example 1
Activity was evaluated according to Example 1 without using any catalyst as a blank test, and it was confirmed that trichloroethylene was hardly decomposed only by irradiation with ultraviolet rays at 360 nm.
[0040]
Comparative Example 2
As titanium oxide, titanium oxide, JRC-TIO-2, which is a reference catalyst of the Catalysis Society of Japan, was used. This catalyst was anatase type crystal powder, and the specific surface area was 18 m 2 / g. The activity evaluation of the catalyst was performed according to Example 1. The results are shown in Table 1.
[0041]
Comparative Example 3
Titanium oxide, JRC I TIO-3, which is a reference catalyst for the Catalysis Society of Japan, was used as titanium oxide. This catalyst was a rutile crystal powder, and the specific surface area was 40 m 2 / g. The activity evaluation of the catalyst was performed according to Example 1. The results are shown in Table 1.
[0042]
[Table 1]
As is apparent from the results shown in Table 1, the flaky titanium oxide photocatalysts of the present invention shown in Examples 1 to 3 are compared with the conventional powdery crystalline titanium oxide photocatalysts shown in Comparative Examples 2 and 3. Thus, it can be seen that the removal rate of organic halogen compounds contained in water is high.
[0044]
【The invention's effect】
The titanium oxide photocatalyst of the present invention exhibits a high organic halogen compound removal rate that is not found in conventional titanium oxide, and an effect that the organic halogen compound can be efficiently removed is obtained.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction pattern of the photocatalyst of the present invention.
FIG. 2 is a scanning electron micrograph of the photocatalyst of the present invention.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17240196A JP3803701B2 (en) | 1996-07-02 | 1996-07-02 | Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17240196A JP3803701B2 (en) | 1996-07-02 | 1996-07-02 | Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1015392A JPH1015392A (en) | 1998-01-20 |
| JP3803701B2 true JP3803701B2 (en) | 2006-08-02 |
Family
ID=15941272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17240196A Expired - Fee Related JP3803701B2 (en) | 1996-07-02 | 1996-07-02 | Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3803701B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4570637B2 (en) * | 2007-04-06 | 2010-10-27 | 石原産業株式会社 | Visible light responsive photocatalyst, method for producing the same, and photocatalyst using the same |
-
1996
- 1996-07-02 JP JP17240196A patent/JP3803701B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1015392A (en) | 1998-01-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5582545B2 (en) | Photocatalyst containing carbon nitride, method for producing the same, and air purification method using the photocatalyst | |
| EP0818239B1 (en) | Photocatalyst, method of producing the photocatalyst, and photocatalytic reaction method | |
| Addamo et al. | Photocatalytic thin films of TiO2 formed by a sol–gel process using titanium tetraisopropoxide as the precursor | |
| JP2008504957A (en) | Catalyst material and method for producing the same | |
| JP5150883B2 (en) | Carbon nanosheet / titanate nanotube composite, carbon nanosheet / titania nanorod composite, production method thereof and use thereof | |
| JP2007528454A (en) | Large surface area ceramic coated fiber | |
| EP1738827A1 (en) | Novel photocatalyst and method for producing same | |
| JP4863290B2 (en) | Method for producing carbon nanosheet composite, and organic pollutant removal method and remover using composite obtained by the method | |
| JPH11197512A (en) | Thin photocatalyst film, photocatalytic reaction method and production of thin photocatalyst film | |
| JP4135907B2 (en) | Visible light active photocatalyst particles | |
| JP3803701B2 (en) | Photocatalyst for removing organic halogen compounds contained in water and method for removing organic halogen compounds contained in water | |
| KR101817855B1 (en) | Photocatalyst for water treatment containing graphene oxide supported with Ag doped zinc oxide, preparation method thereof and using thereof | |
| JP2001259436A (en) | Fe2O3 PHOTOCATALYST COMPONENT, PHOTOCATALYST AND METHOD OF REMOVING NITROGEN OXIDE IN AIR | |
| JP2001276615A (en) | Titanium oxide powder for photocatalyst | |
| JPH0857323A (en) | Catalyst for decomposition of volatile organic halogen compound and production thereof | |
| JP3721430B2 (en) | Underwater organochlorine purification catalyst | |
| JP3752552B2 (en) | Photocatalyst for removal of organochlorine compounds in water | |
| JPH08252461A (en) | Preparation of photocatalyst | |
| JP4858988B2 (en) | Method for producing carbon nanosheet composite without firing, and organic pollutant removal method and remover using composite obtained by the method | |
| JP3579709B2 (en) | Hollandite-type photocatalyst and method for removing phenol in water using the catalyst | |
| JP4089989B2 (en) | Method of treating harmful substances in water with titanium oxide photocatalyst | |
| JP2001246261A (en) | Photocatalyst | |
| JP2001269671A (en) | Method for fast decomposition and removal of organic chlorine compound by hollandite type photocatalyst | |
| JP3062740B2 (en) | Photocatalyst for reductive decomposition and removal of nitric oxide in gas phase and purification method using the catalyst | |
| CN115090304B (en) | F-TiO 2-x Preparation method of Pt nano photocatalyst film and application of Pt nano photocatalyst film in air purification |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050421 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050517 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20060307 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20060320 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20060320 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090519 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100519 Year of fee payment: 4 |
|
| LAPS | Cancellation because of no payment of annual fees |