JP5323218B2 - Method for removing heavy metal ions from a liquid containing heavy metal ions - Google Patents
Method for removing heavy metal ions from a liquid containing heavy metal ions Download PDFInfo
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- JP5323218B2 JP5323218B2 JP2012030125A JP2012030125A JP5323218B2 JP 5323218 B2 JP5323218 B2 JP 5323218B2 JP 2012030125 A JP2012030125 A JP 2012030125A JP 2012030125 A JP2012030125 A JP 2012030125A JP 5323218 B2 JP5323218 B2 JP 5323218B2
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- cerium oxide
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- 150000002500 ions Chemical class 0.000 title claims description 60
- 229910001385 heavy metal Inorganic materials 0.000 title claims description 50
- 239000007788 liquid Substances 0.000 title claims description 24
- 238000000034 method Methods 0.000 title claims description 20
- 239000011941 photocatalyst Substances 0.000 claims description 67
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 44
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 44
- 229910052712 strontium Inorganic materials 0.000 claims description 21
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 21
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 10
- 239000000758 substrate Substances 0.000 claims description 10
- 239000011575 calcium Substances 0.000 claims description 8
- 229910052746 lanthanum Inorganic materials 0.000 claims description 8
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 229910052727 yttrium Inorganic materials 0.000 claims description 6
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 6
- 239000002243 precursor Substances 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 4
- 239000002657 fibrous material Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000010409 thin film Substances 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 claims 1
- 238000000576 coating method Methods 0.000 claims 1
- 239000007864 aqueous solution Substances 0.000 description 18
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 230000001699 photocatalysis Effects 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 7
- RVPVRDXYQKGNMQ-UHFFFAOYSA-N lead(2+) Chemical compound [Pb+2] RVPVRDXYQKGNMQ-UHFFFAOYSA-N 0.000 description 7
- 229910052697 platinum Inorganic materials 0.000 description 7
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 7
- 229910052753 mercury Inorganic materials 0.000 description 6
- WLZRMCYVCSSEQC-UHFFFAOYSA-N cadmium(2+) Chemical compound [Cd+2] WLZRMCYVCSSEQC-UHFFFAOYSA-N 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 5
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910000510 noble metal Inorganic materials 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910000018 strontium carbonate Inorganic materials 0.000 description 5
- 229910052785 arsenic Inorganic materials 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000012085 test solution Substances 0.000 description 4
- 229910052684 Cerium Inorganic materials 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 3
- 229910052793 cadmium Inorganic materials 0.000 description 3
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000000295 emission spectrum Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 230000001678 irradiating effect Effects 0.000 description 3
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- -1 respectively Chemical compound 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 239000005995 Aluminium silicate Substances 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 235000012211 aluminium silicate Nutrition 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- XIEPJMXMMWZAAV-UHFFFAOYSA-N cadmium nitrate Inorganic materials [Cd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XIEPJMXMMWZAAV-UHFFFAOYSA-N 0.000 description 2
- QCUOBSQYDGUHHT-UHFFFAOYSA-L cadmium sulfate Chemical compound [Cd+2].[O-]S([O-])(=O)=O QCUOBSQYDGUHHT-UHFFFAOYSA-L 0.000 description 2
- 229910000331 cadmium sulfate Inorganic materials 0.000 description 2
- 150000001785 cerium compounds Chemical class 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000003365 glass fiber Substances 0.000 description 2
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 2
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 2
- RLJMLMKIBZAXJO-UHFFFAOYSA-N lead nitrate Chemical compound [O-][N+](=O)O[Pb]O[N+]([O-])=O RLJMLMKIBZAXJO-UHFFFAOYSA-N 0.000 description 2
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- NMHMNPHRMNGLLB-UHFFFAOYSA-N phloretic acid Chemical compound OC(=O)CCC1=CC=C(O)C=C1 NMHMNPHRMNGLLB-UHFFFAOYSA-N 0.000 description 2
- 238000002256 photodeposition Methods 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 239000002759 woven fabric Substances 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052768 actinide Inorganic materials 0.000 description 1
- 150000001255 actinides Chemical class 0.000 description 1
- 239000003463 adsorbent Substances 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
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- VYLVYHXQOHJDJL-UHFFFAOYSA-K cerium trichloride Chemical compound Cl[Ce](Cl)Cl VYLVYHXQOHJDJL-UHFFFAOYSA-K 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 229910001429 cobalt ion Inorganic materials 0.000 description 1
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000695 excitation spectrum Methods 0.000 description 1
- 239000012013 faujasite Substances 0.000 description 1
- 239000012210 heat-resistant fiber Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 229910000464 lead oxide Inorganic materials 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- VSQYNPJPULBZKU-UHFFFAOYSA-N mercury xenon Chemical compound [Xe].[Hg] VSQYNPJPULBZKU-UHFFFAOYSA-N 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- 238000013032 photocatalytic reaction Methods 0.000 description 1
- 238000006552 photochemical reaction Methods 0.000 description 1
- 230000001443 photoexcitation Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000001055 reflectance spectroscopy Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
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- Treatment Of Water By Oxidation Or Reduction (AREA)
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Description
本発明は、液中に存在する重金属イオンを光を照射することによって酸化あるいは還元し、重金属あるいは酸化物として析出させることによって除去することのできる光触媒を使用して重金属イオンを含有する液体から重金属イオンを除去する方法に関する。 The present invention uses a photocatalyst that can be removed by oxidizing or reducing heavy metal ions present in a liquid by irradiating light and precipitating them as heavy metals or oxides. The present invention relates to a method for removing ions.
近年、工場排水や、鉱山跡から溶出した鉛、カドミウム、６価クロム、ヒ素、水銀等の有害重金属による干潟、運河、河川、泥地等の汚染が深刻化しており、健全な生態系の保持の観点から早急な対策が求められている。
めっき工業や金属加工業から排出される重金属の捕集については、これまでに化学的にキレートを形成させることによって不溶化する方法、イオン交換法によって重金属を吸着剤により固定する方法、焼却炉で高温処理し重金属成分を分離する方法等により回収されている。これらの方法はいずれもシステムが複雑化するために処理コストが高くなるとともに、既に環境中に放出された重金属、特に低濃度の重金属については回収が困難であるという問題がある。
In recent years, pollution of tidal flats, canals, rivers, swamps, etc. by toxic heavy metals such as industrial wastewater and lead, cadmium, hexavalent chromium, arsenic, and mercury eluted from mine traces has become serious, maintaining a healthy ecosystem From this point of view, immediate measures are required.
Regarding the collection of heavy metals discharged from the plating industry and metal processing industry, the method of insolubilization by forming a chelate chemically, the method of fixing heavy metals with an adsorbent by ion exchange method, the high temperature in the incinerator It is recovered by a method of treating and separating heavy metal components. All of these methods have a problem that the processing cost becomes high due to the complexity of the system and that it is difficult to recover heavy metals that have already been released into the environment, particularly low-concentration heavy metals.
一方、光触媒については、光照射によって生じる電子で反応物を還元、正孔で反応物を酸化する能力を持つことが既に知られており、この技術を応用した有害物質の分解除去、光化学反応、および水分解反応などの化学反応プロセスは、環境およびエネルギー問題の観点から近年、注目を集めている。（例えば、非特許文献１，２及び特許文献１，２参照）
On the other hand, photocatalysts are already known to have the ability to reduce reactants with electrons generated by light irradiation and to oxidize reactants with holes. Decomposition and removal of harmful substances using this technology, photochemical reactions, In addition, chemical reaction processes such as water splitting reactions have recently attracted attention in terms of environmental and energy issues. (For example, see
上記の非特許文献１には、酸化チタンに白金を光電着した光触媒による鉛イオンの光析出が開示されている。この文献には、当該触媒に光を照射することにより水中の鉛濃度が減少することが報告されているが、犠牲試薬としてメタノールを用いている。光励起により生成した電子はメタノールを還元して水素を発生させ、正孔は鉛を酸化析出させる。しかしながら、この方法では助触媒として高価な貴金属を用いることや、犠牲試薬としてメタノールを必要とするといった問題点がある。
非特許文献２には、酸化チタンを光触媒とした、鉛、マンガン、タリウム、コバルトイオン等の重金属イオンの光化学的沈殿法が開示されている。当該触媒は、非特許文献１に記載の触媒と同様に助触媒として白金を担持することによって、光照射により高い効率で重金属を光電着することができるものであるが、白金が存在しない場合には著しく電着速度が遅いことが報告されている。そして、白金を担持した酸化チタン触媒を用いることによって、光照射６０分後において鉛の濃度は９１％減少することが報告されている。
Non-Patent Document 2 discloses a photochemical precipitation method of heavy metal ions such as lead, manganese, thallium and cobalt ions using titanium oxide as a photocatalyst. The catalyst is capable of photo-depositing heavy metals with high efficiency by light irradiation by supporting platinum as a co-catalyst in the same manner as the catalyst described in Non-Patent
また、特許文献１及び２には、ガラス繊維からなる織布に貴金属を担持させずに酸化チタンを被覆した光触媒を用いることにより、液中の水銀、鉛、カドミウム、ヒ素、銅、マンガン、６価クロム等の重金属イオンを除去することが開示されている。
これらの文献に記載された光触媒はいずれも紫外光により励起される酸化チタンを用いるものである。したがって、環境中に存在する低濃度の重金属イオンを除去するには、さらに高い光触媒機能を有するとともに、白金等の高価な貴金属を必要としない低コストの光触媒の開発が求められていた。 All of the photocatalysts described in these documents use titanium oxide excited by ultraviolet light. Therefore, in order to remove low-concentration heavy metal ions present in the environment, development of a low-cost photocatalyst that has a higher photocatalytic function and does not require expensive noble metals such as platinum has been demanded.
したがって、本発明は白金等の貴金属を必要とせずに低コストでかつ効率よく、液中に存在する重金属イオンを光照射により酸化あるいは還元し、金属あるいは酸化物として析出させることによって除去することのできる光触媒を使用して重金属イオンを含有する液体から重金属イオンを除去する方法を提供することを目的とする。 Therefore, the present invention eliminates the need for removing a heavy metal ion present in a liquid by oxidizing or reducing it by light irradiation and precipitating it as a metal or an oxide without requiring a noble metal such as platinum. It is an object of the present invention to provide a method for removing heavy metal ions from a liquid containing heavy metal ions using a photocatalyst that can be used.
本発明では、上記課題を解決するために、次の構成１〜４を採用する。
１．重金属イオンを含有する液体を、（１）酸化セリウムに、（２）カルシウム、ストロンチウム、イットリウム、ランタンからなる群から選択された少なくとも１種の異種元素を、酸化セリウムを基準として０．１〜１００モル％添加混合した後に、得られた前駆体を空気中で５００〜１４００℃の温度に加熱してなる酸化セリウム光触媒、と接触させて光照射することを特徴とする、重金属イオンを含有する液体から重金属イオンを除去する方法。
２．前記酸化セリウム光触媒が基材表面に薄膜状に被覆したものであることを特徴とする、１に記載の重金属イオンを含有する液体から重金属イオンを除去する方法。
３．前記基材が板状体であることを特徴とする、２に記載の重金属イオンを含有する液体から重金属イオンを除去する方法。
４．前記基材が多孔質材料又は繊維状材料であることを特徴とする、２に記載の重金属イオンを含有する液体から重金属イオンを除去する方法。
本発明において重金属を含有する液体とは、水又は水と水溶性有機溶媒との混合物中に、重金属イオンを溶解又は分散させた液体を意味する。
In the present invention, the following
1. The liquid containing heavy metal ions is (1) cerium oxide, (2) at least one different element selected from the group consisting of calcium, strontium, yttrium, and lanthanum is 0.1 to 100 based on cerium oxide. A liquid containing heavy metal ions, which is irradiated with light after contacting with a cerium oxide photocatalyst obtained by heating the obtained precursor in air to a temperature of 500 to 1400 ° C. after addition and mixing by mol%. To remove heavy metal ions from the surface.
2. 2. The method for removing heavy metal ions from a liquid containing heavy metal ions according to 1, wherein the cerium oxide photocatalyst is coated on a substrate surface in a thin film shape .
3. 2. The method for removing heavy metal ions from a liquid containing heavy metal ions according to 2 , wherein the substrate is a plate-like body .
4). The method for removing heavy metal ions from a liquid containing heavy metal ions according to 2 , wherein the substrate is a porous material or a fibrous material .
In the present invention, the liquid containing a heavy metal means a liquid in which heavy metal ions are dissolved or dispersed in water or a mixture of water and a water-soluble organic solvent.
本発明で使用する酸化セリウム光触媒は、液中に存在する水銀、鉛、カドミウム、ヒ素、銅、マンガン、６価クロム等の重金属イオンを光照射により酸化あるいは還元し、金属あるいは酸化物として析出させることによって効率よく除去することができる。また、白金等の貴金属を必要とせずに低コストで光触媒を製造することが可能であるとともに、低濃度の重金属イオンも容易に捕集することができることから、水質系の浄化等に極めて有用である。 The cerium oxide photocatalyst used in the present invention oxidizes or reduces heavy metal ions such as mercury, lead, cadmium, arsenic, copper, manganese, hexavalent chromium, etc. present in the liquid, and deposits them as metal or oxide. Can be removed efficiently. In addition, it is possible to produce a photocatalyst at a low cost without the need for noble metals such as platinum, and it is possible to easily collect low-concentration heavy metal ions. is there.
本発明で使用する光触媒を製造する好ましい手順の例について、以下に説明する。
１）はじめに、粉末状の（１）酸化セリウムと（２）カルシウム、ストロンチウム、イットリウム、ランタンからなる群から選択された異種元素を含む化合物の１種又は２種以上を、（２）異種元素の添加量が（１）酸化セリウムを基準として０．１〜１００モル％の範囲で混合して前駆体を得る。
２）次に、前駆体を空気中、５００〜１４００℃の温度に加熱する。
An example of a preferable procedure for producing the photocatalyst used in the present invention will be described below.
1) First, one or more kinds of compounds containing different elements selected from the group consisting of (1) cerium oxide and (2) calcium, strontium, yttrium, and lanthanum in the form of powder; (2) The precursor is obtained by mixing in an amount of (1) 0.1 to 100 mol% based on cerium oxide.
2) Next, the precursor is heated to a temperature of 500 to 1400 ° C. in air.
上記１）の別法として、１’）（１）硝酸セリウムあるいは塩化セリウムと、（２）ストロンチウム、カルシウム、イットリウム、ランタンからなる群から選択された異種元素を含む水溶性化合物を、（２）異種元素の添加量が（１）セリウム化合物を基準として０．１〜１００モル％の範囲で水に溶解させ、ｐＨを７以上に調製して得られた沈殿を前駆体とすることもできる。 As another method of 1), a water-soluble compound containing 1 ′), (1) cerium nitrate or cerium chloride, and (2) a heterogeneous element selected from the group consisting of strontium, calcium, yttrium, and lanthanum, (2) Precipitation obtained by dissolving the water in the range of 0.1 to 100 mol% based on the cerium compound and adding pH of 7 or more can be used as a precursor.
（２）異種元素の添加量は、（１）セリウム化合物を基準として０．１〜１００モル％の範囲で選択することができるが、通常は１〜５０モル％、特に５〜２０モル％程度とすることが好ましい。
得られたセリウム光触媒は、粉末状で処理対象とする液中に分散させて使用することができる。また、板状体、多孔質材料、繊維状材料等の基材表面に、光触媒を薄膜状に被覆したものを、処理対象とする重金属イオンを含有する液体と接触させて使用しても良い。粉末状の光触媒を液中に分散させて使用する場合には、光照射の際に光触媒反応が液体の表面でのみ進行することがあり、また処理後に光触媒を分離する工程が必要となる。これに対して、基材表面に光触媒を被覆したものでは、このような問題点が解消されるので好ましい。
(2) The addition amount of the different element can be selected in the range of 0.1 to 100 mol% based on (1) the cerium compound, but usually 1 to 50 mol%, particularly about 5 to 20 mol%. It is preferable that
The obtained cerium photocatalyst can be used by being dispersed in a liquid to be treated in a powder form. Moreover, you may use what coat | covered the photocatalyst on the surface of base materials, such as a plate-shaped body, a porous material, and a fibrous material, with the liquid containing the heavy metal ion made into a process target. When a powdery photocatalyst is used dispersed in a liquid, the photocatalytic reaction may proceed only on the surface of the liquid during light irradiation, and a step of separating the photocatalyst after the treatment is required. On the other hand, it is preferable to coat the surface of the substrate with a photocatalyst because such problems are solved.
板状体の基材としては、例えば各種のセラミックス板、ガラス板、金属板、耐熱性プラスチック板等を使用することができる。
また、多孔質基材としては、各種のゼオライト類を使用することができる。好ましい、多孔質基材としては、例えばKaolin、ZSM-5、Mordenite、Faujasite等が挙げられる。
さらに、繊維状基材としては、ガラス繊維、セラミックス繊維、金属繊維、炭素繊維等の耐熱性繊維を単繊維、織布、不織布等の形態で使用することができる。
As the base material of the plate-like body, for example, various ceramic plates, glass plates, metal plates, heat resistant plastic plates and the like can be used.
Various types of zeolites can be used as the porous substrate. Preferred examples of the porous substrate include Kaolin, ZSM-5, Mordenite, and Faujasite.
Furthermore, as the fibrous substrate, heat-resistant fibers such as glass fibers, ceramic fibers, metal fibers, and carbon fibers can be used in the form of single fibers, woven fabrics, nonwoven fabrics, and the like.
次に本発明で使用する光触媒を製造する方法、及び得られた光触媒を使用して重金属イオンを含有する液体から重金属イオンを除去する方法、について実施例によりさらに詳細に説明するが、以下の具体例は本発明を限定するものではない。
以下の例では、光触媒の性能は光照射前後の水溶液中の重金属イオンの濃度を、ＩＣＰ発光分析法によりつぎのようにして測定することにより評価した。
（ＩＣＰ発光分析法）
ＩＣＰ発光分光装置（島津社製ＩＣＰＳ−７５１０）を用い、重金属を含む水溶液をアルゴンプラズマ中に噴霧し、そこから放出される元素固有の光の波長の強度を計測した。既知濃度の重金属イオンを含む溶液を標準試料とし、その強度と比較することにより該水溶液の重金属イオン濃度を決定した。
Next, a method for producing a photocatalyst used in the present invention and a method for removing heavy metal ions from a liquid containing heavy metal ions using the obtained photocatalyst will be described in more detail with reference to the following examples. The examples are not intended to limit the invention.
In the following examples, the performance of the photocatalyst was evaluated by measuring the concentration of heavy metal ions in the aqueous solution before and after the light irradiation by ICP emission analysis as follows.
(ICP emission spectrometry)
Using an ICP emission spectrometer (ICPS-7510 manufactured by Shimadzu Corp.), an aqueous solution containing heavy metal was sprayed into argon plasma, and the intensity of the wavelength of light unique to the element emitted therefrom was measured. A solution containing a known concentration of heavy metal ions was used as a standard sample, and the concentration of the heavy metal ions in the aqueous solution was determined by comparison with the strength.
（実施例1）
粉末状の酸化セリウムと炭酸ストロンチウムを、セリウム元素に対してストロンチウム元素が１０％のモル比となるように混合し、大気中で、１０００℃の温度で１０時間焼成して、ストロンチウム１０モル％添加酸化セリウム光触媒を作製した。
得られた光触媒のＸ線回折パターンを図１に、紫外可視拡散反射スペクトルを図２に、そして発光スペクトルを図３に示す。
(Example 1)
Powdered cerium oxide and strontium carbonate are mixed so that the strontium element has a molar ratio of 10% with respect to the cerium element, calcined in air at a temperature of 1000 ° C. for 10 hours, and added with 10 mol% of strontium. A cerium oxide photocatalyst was prepared.
The X-ray diffraction pattern of the obtained photocatalyst is shown in FIG. 1, the ultraviolet-visible diffuse reflection spectrum is shown in FIG. 2, and the emission spectrum is shown in FIG.
図１のＸ線回折パターンによると、ストロンチウム添加酸化セリウムは酸化セリウムと同様な結晶構造を有し、ほぼ単一相であること、および高い結晶性を有することが判る。また、図２の可視紫外拡散反射スペクトルから、ストロンチウムを添加した酸化セリウムの光吸収特性は、酸化セリウムとほぼ一致し、吸収端は４５０ｎｍ付近であることが判る。そして、図３の発光スペクトルから、ストロンチウムを添加することにより、４７０ｎｍ付近に発光ピークが出現し、その励起スペクトルの最大波長は２７５ｎｍであることが判る。 According to the X-ray diffraction pattern of FIG. 1, it can be seen that strontium-doped cerium oxide has a crystal structure similar to that of cerium oxide, is almost single phase, and has high crystallinity. Further, from the visible ultraviolet diffuse reflection spectrum of FIG. 2, it can be seen that the light absorption characteristics of cerium oxide to which strontium is added are almost the same as cerium oxide, and the absorption edge is around 450 nm. From the emission spectrum of FIG. 3, it can be seen that by adding strontium, an emission peak appears in the vicinity of 470 nm, and the maximum wavelength of the excitation spectrum is 275 nm.
（光触媒の活性試験）
硝酸鉛又は硫酸鉛を純水に溶解して１００ｐｐｍの濃度の鉛イオンを含む水溶液を調製した。石英窓を取り付けた反応セルに、この鉛イオンを含む水溶液３０ｍＬと上記で得られた粉末状のストロンチウム添加酸化セリウム光触媒０．２５ｇを収容し、マグネチックスターラーにより攪拌懸濁させた。この懸濁液に、２５０Ｗ水銀キセノンランプを用いて光を３時間照射した。懸濁液を遠心分離することにより粉末光触媒を分離し、光照射前後の鉛イオンの濃度をＩＣＰ発光分析法に求めて、その結果を図４に示した。
図４にみられるように、光照射前の水溶液中の鉛イオンの濃度は仕込み量に近い１０３．２１ｐｐｍであったが、光照射後は０．００ｐｐｍに低下した。また、光照射前の光触媒は白色を呈していたが、光照射後は褐色となり光触媒表面に鉛を含む化合物が光析出したことが確認された。通常の紫外線可視拡散反射スペクトル法及びＸ線光電子分光法によって、光触媒表面に酸化鉛が存在することが判明した。
(Photocatalytic activity test)
Lead nitrate or lead sulfate was dissolved in pure water to prepare an aqueous solution containing 100 ppm of lead ions. In a reaction cell equipped with a quartz window, 30 mL of the aqueous solution containing lead ions and 0.25 g of the powdered strontium-added cerium oxide photocatalyst obtained above were accommodated and suspended by stirring with a magnetic stirrer. This suspension was irradiated with light for 3 hours using a 250 W mercury xenon lamp. The powder photocatalyst was separated by centrifuging the suspension, and the concentration of lead ions before and after the light irradiation was determined by ICP emission analysis. The result is shown in FIG.
As seen in FIG. 4, the concentration of lead ions in the aqueous solution before light irradiation was 103.21 ppm, which was close to the charged amount, but decreased to 0.00 ppm after light irradiation. Moreover, although the photocatalyst before light irradiation was white, it became brown after light irradiation, and it was confirmed that the compound containing lead photodeposited on the photocatalyst surface. It was found that lead oxide was present on the surface of the photocatalyst by ordinary ultraviolet visible diffuse reflection spectroscopy and X-ray photoelectron spectroscopy.
光照射によって鉛イオンが酸化析出することを実証するために、対照として上記で得られた粉末状のストロンチウム添加酸化セリウム光触媒０．２５ｇを鉛イオン１００ｐｐｍを含む水溶液３０ｍＬに懸濁させて、光照射を行わずに３時間攪拌した後に鉛イオンの濃度を測定した結果を図４に示した。
図４にみられるように、水溶液中の鉛イオンは光触媒上に吸着し、その濃度は３４．０１ｐｐｍになった。また、光照射を行わない場合には、光触媒の色に変化はみられず白色のままであった。
In order to demonstrate that lead ions are oxidized and precipitated by light irradiation, 0.25 g of the powdered strontium-doped cerium oxide photocatalyst obtained above as a control is suspended in 30 mL of an aqueous solution containing 100 ppm of lead ions, and light irradiation is performed. The result of measuring the concentration of lead ions after stirring for 3 hours without performing was shown in FIG.
As seen in FIG. 4, the lead ions in the aqueous solution were adsorbed on the photocatalyst, and the concentration thereof was 34.01 ppm. Moreover, when light irradiation was not performed, the color of the photocatalyst did not change and remained white.
（実施例２）
実施例１において、炭酸ストロンチウムに代えて酸化ランタンを用いた以外は実施例１と同様にして、ランタン１０モル％添加酸化セリウム光触媒を作製した。この光触媒を用いて実施例１と同様にして３時間光照射して活性試験を行ったところ、鉛イオンの濃度は０．２２ｐｐｍに低下し、光触媒の色は褐色に変化した。これに対して、光照射を行わずに３時間攪拌したものでは鉛イオンの濃度は２５．８６ｐｐｍであり、光触媒の色は変化しなかった。（図４参照）
(Example 2)
In Example 1, a cerium oxide photocatalyst added with 10 mol% lanthanum was prepared in the same manner as in Example 1 except that lanthanum oxide was used instead of strontium carbonate. Using this photocatalyst, the activity test was carried out by irradiating with light for 3 hours in the same manner as in Example 1. As a result, the lead ion concentration decreased to 0.22 ppm, and the color of the photocatalyst changed to brown. In contrast, in the case of stirring for 3 hours without light irradiation, the concentration of lead ions was 25.86 ppm, and the color of the photocatalyst did not change. (See Figure 4)
（比較例１）
比較のために、光触媒として異種元素を添加していない酸化セリウム及び市販の酸化チタン（Degussa P-25）を用いて、実施例１と同様にして光触媒の活性試験を行った結果を図４に示した。
図４にみられるように、異種元素を添加していない酸化セリウムでは、光触媒表面への吸着により、光照射をせずに３時間攪拌したものでは鉛イオンの濃度は９７．２０ｐｐｍ、光照射をしたものでは９８．３４ｐｐｍとなり、光照射による鉛イオンの濃度の低下はみられなかった。また、光照射後にも光触媒の色の変化は認められなかった。
また、酸化チタンでは、光触媒表面への吸着により、光照射をせずに３時間攪拌したものでは鉛イオンの濃度は７６．３５ｐｐｍ、光照射をしたものでは７６．７０ｐｐｍとなり、光照射によって鉛イオンの濃度は殆ど変化しなかった。また、光照射後にも光触媒の色の変化は認められず、白色のままであった。
(Comparative Example 1)
For comparison, FIG. 4 shows the results of a photocatalytic activity test conducted in the same manner as in Example 1 using cerium oxide to which a different element was not added as a photocatalyst and commercially available titanium oxide (Degussa P-25). Indicated.
As shown in FIG. 4, in the case of cerium oxide not added with different elements, the lead ion concentration is 97.20 ppm and the light irradiation is carried out by stirring for 3 hours without light irradiation due to adsorption to the photocatalyst surface. As a result, the concentration was 98.34 ppm, and no decrease in the lead ion concentration due to light irradiation was observed. Further, no change in the color of the photocatalyst was observed after the light irradiation.
In addition, in titanium oxide, the concentration of lead ions is 76.35 ppm when the mixture is stirred for 3 hours without light irradiation due to adsorption to the surface of the photocatalyst, and 76.70 ppm when the light irradiation is performed. The concentration of was almost unchanged. In addition, no change in the color of the photocatalyst was observed even after light irradiation, and it remained white.
（実施例３）
実施例１において、酸化セリウムに対する炭酸ストロンチウムの混合量を変えた以外は実施例１と同様にして、ストロンチウムの添加量が２０モル％及び５０モル％のストロンチウム添加酸化セリウム光触媒を作製した。これらの光触媒を使用して活性試験を行った結果を、実施例１で得られたストロンチウムの添加量が１０モル％の酸化セリウム光触媒による結果とともに図５に示した。
ストロンチウムを各１０、２０、５０モル％添加した酸化セリウム光触媒では、光照射３０分後に鉛イオンの濃度の濃度はそれぞれ２０．０８ｐｐｍ、０．００ｐｐｍ，１４．７８ｐｐｍに減少し、ストロンチウムの添加量が２０モル％の光触媒で最も高い鉛イオンの濃度の低下（光析出効果）が認められた。また、いずれの光触媒においても、光照射１２０分後には鉛イオンの濃度は０．００ｐｐｍになった。
(Example 3)
In Example 1, a strontium-added cerium oxide photocatalyst having 20 mol% and 50 mol% of strontium added was prepared in the same manner as in Example 1 except that the amount of strontium carbonate mixed with cerium oxide was changed. The results of the activity test using these photocatalysts are shown in FIG. 5 together with the results obtained with the cerium oxide photocatalyst having an addition amount of strontium of 10 mol% obtained in Example 1.
In the cerium oxide photocatalyst added with 10, 20, and 50 mol% of strontium, the concentration of lead ions decreased to 20.08 ppm, 0.00 ppm, and 14.78 ppm after 30 minutes of light irradiation, respectively. The highest decrease in lead ion concentration (photodeposition effect) was observed with 20 mol% of the photocatalyst. Further, in any photocatalyst, the concentration of lead ions became 0.00 ppm after 120 minutes of light irradiation.
（実施例４）
実施例１において、炭酸ストロンチウムに代えてそれぞれ酸化イットリウム、及び炭酸カルシウムを用いた以外は実施例１と同様にして、イットリウム１０モル％添加酸化セリウム光触媒及びカルシウム１０モル％添加酸化セリウム光触媒を作製した。これらの光触媒、並びに実施例１で得られたストロンチウム１０モル％添加酸化セリウム光触媒及び実施例２で得られたランタン１０モル％添加酸化セリウム光触媒を用いて活性試験を行った結果を図６に示した。いずれの光触媒においても、光照射時間の経過とともに顕著な鉛イオン濃度の低下がみられ、光触媒の色は褐色に変化した。
Example 4
In Example 1, except that yttrium oxide and calcium carbonate were used in place of strontium carbonate, respectively,
（比較例２）
実施例１において、炭酸ストロンチウムに代えてそれぞれランタン以外のランタノイド元素１４種、アクチノイド元素１５種、インジウム、ニッケル、銅、及び亜鉛の各酸化物を用いた以外は実施例１と同様にして、これらの異種元素を１０モル％添加した酸化セリウム光触媒を作製した。これらの光触媒を使用して同様に活性試験を行ったが、光照射による鉛イオンの捕集効果は認められなかった。
(Comparative Example 2)
In Example 1, in place of strontium carbonate, 14 kinds of lanthanoid elements other than lanthanum, 15 kinds of actinoid elements, oxides of indium, nickel, copper, and zinc were used in the same manner as in Example 1, A cerium oxide photocatalyst added with 10 mol% of these different elements was prepared. Although the activity test was similarly performed using these photocatalysts, the lead ion collection effect by light irradiation was not recognized.
（実施例５）
硝酸カドミウム又は硫酸カドミウムを純水に溶解することにより５０ｐｐｍの濃度のカドミウムイオンを含む水溶液を調製した。この水溶液を試験液として、実施例１で得られたストロンチウム１０モル％添加酸化セリウム光触媒を用いて、実施例１と同様にして活性試験を行った結果を図７に示した。
図７にみられるように、光照射を３時間行った場合には、カドミウムイオン濃度は９．４５ｐｐｍに低下した。これに対して、光照射を行わずに攪拌のみを３時間行った場合には、カドミウムイオンの濃度は４７．４３ｐｐｍであった。
(Example 5)
An aqueous solution containing cadmium ions at a concentration of 50 ppm was prepared by dissolving cadmium nitrate or cadmium sulfate in pure water. Using this aqueous solution as a test solution, using the
As seen in FIG. 7, the cadmium ion concentration decreased to 9.45 ppm when light irradiation was performed for 3 hours. On the other hand, when only stirring was performed for 3 hours without light irradiation, the concentration of cadmium ions was 47.43 ppm.
（実施例６）
硝酸鉛又は硫酸鉛、並びに硝酸カドミウム又は硫酸カドミウムを純水に溶解することにより鉛イオン５０ｐｐｍ及びカドミウムイオン５０ｐｐｍを含む水溶液を調製した。この混合水溶液を試験液として、実施例１で得られたストロンチウム１０モル％添加酸化セリウム光触媒を用いて、実施例１と同様にして活性試験を行った結果を図８に示した。
図８にみられるように、光照射を３時間行うことにより、鉛イオン濃度は０．００ｐｐｍ、カドミウムイオン濃度は２．３２ｐｐｍに低下し、混合試験液に対しても光捕集効果が認められた。
(Example 6)
An aqueous solution containing 50 ppm of lead ions and 50 ppm of cadmium ions was prepared by dissolving lead nitrate or lead sulfate, and cadmium nitrate or cadmium sulfate in pure water. Using this mixed aqueous solution as a test solution, using the cerium oxide photocatalyst with 10 mol% strontium obtained in Example 1, the results of an activity test similar to Example 1 are shown in FIG.
As shown in FIG. 8, by performing light irradiation for 3 hours, the lead ion concentration is lowered to 0.00 ppm and the cadmium ion concentration is reduced to 2.32 ppm, and the light collection effect is recognized also for the mixed test solution. It was.
（実施例７）
６価クロムイオン５０ｐｐｍ、ヒ素イオン５０ｐｐｍ、及び水銀イオン５０ｐｐｍを含む混合水溶液を試験液として、実施例１で得られたストロンチウム１０モル％添加酸化セリウム光触媒を用いて、実施例１と同様にして活性試験を行ったところ、３時間の光照射により各重金属イオンの濃度は数ｐｐｍ以下に低下した。
(Example 7)
Using a mixed aqueous solution containing 50 ppm of hexavalent chromium ions, 50 ppm of arsenic ions, and 50 ppm of mercury ions as a test solution, activity was carried out in the same manner as in Example 1 using the cerium oxide photocatalyst added with 10 mol% of strontium obtained in Example 1. When the test was conducted, the concentration of each heavy metal ion was lowered to several ppm or less by light irradiation for 3 hours.
（実施例８）
実施例１で得られたストロンチウム１０モル％添加酸化セリウム光触媒を、水ガラス： 光触媒が１：１００の重量比で混合し、縦３０ｃｍ、横３０ｃｍ、厚さ１ｍｍのセラミックス板（シリカーアルミナ複合材料）の表面に塗布し、大気中、約１０００℃で１０時間焼成することによって、セラミックス板の表面に厚さ約10μｍの光触媒膜を形成した。また、同様にして、縦３０ｃｍ、横３０ｃｍ、厚さ１ｍｍのガラス板の表面に厚さ約１０μｍの光触媒膜を形成した。
これらの光触媒材料を鉛イオンを含有する水溶液に浸して、２５０Ｗの高圧水銀ランプを用いて光を照射したところ、水溶液中の鉛イオンの濃度は時間の経過とともに低下し、鉛イオンの光捕集効果が認められた。
(Example 8)
The
When these photocatalyst materials are immersed in an aqueous solution containing lead ions and irradiated with light using a 250 W high-pressure mercury lamp, the concentration of lead ions in the aqueous solution decreases with time, and light collection of lead ions occurs. The effect was recognized.
（実施例９）
セリウム元素に対してストロンチウム元素が１０モル％になるように、硝酸セリウム及び硝酸ストロンチウムを純水に対して１０重量％になるように溶解し、得られた水溶液を多孔質材料であるゼオライト（Kaolin, SIGMA-ALDRICH）に対して５重量％の濃度で含浸させた後に、大気中、１０００℃で１０時間焼成した。
これらの光触媒材料を鉛イオンを含有する水溶液に浸して、２５０Ｗの高圧水銀ランプを用いて光を照射したところ、水溶液中の鉛イオンの濃度は時間の経過とともに低下し、鉛イオンの光捕集効果が認められた。
Example 9
Cerium nitrate and strontium nitrate are dissolved so as to be 10% by weight with respect to pure water so that the strontium element is 10 mol% with respect to the cerium element, and the resulting aqueous solution is used as a porous material zeolite (Kaolin , SIGMA-ALDRICH), and then baked at 1000 ° C. for 10 hours in the atmosphere.
When these photocatalyst materials are immersed in an aqueous solution containing lead ions and irradiated with light using a 250 W high-pressure mercury lamp, the concentration of lead ions in the aqueous solution decreases with time, and light collection of lead ions occurs. The effect was recognized.
本発明で得られる異種元素を添加した酸化セリウム光触媒は、重金属イオンを含有する液体から重金属イオンを低コストで極めて効率良く捕集することができるものであり、重金属で汚染された水質系の浄化等に有用な材料となる。
The cerium oxide photocatalyst added with different elements obtained in the present invention is capable of collecting heavy metal ions from a liquid containing heavy metal ions very efficiently at a low cost, and purifies a water quality system contaminated with heavy metals. It becomes a useful material for such as.
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