JP2011148697A - Method for evaluating crystallinity of titanium oxide particle, and method for measuring surface defect density of the same particle - Google Patents
Method for evaluating crystallinity of titanium oxide particle, and method for measuring surface defect density of the same particle Download PDFInfo
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims abstract description 105
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 26
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- 239000001301 oxygen Substances 0.000 claims abstract description 13
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 13
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- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims abstract description 7
- 230000001678 irradiating effect Effects 0.000 claims abstract description 7
- 238000000354 decomposition reaction Methods 0.000 abstract description 18
- 239000000243 solution Substances 0.000 abstract description 4
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- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 5
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 4
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- FIKAKWIAUPDISJ-UHFFFAOYSA-L paraquat dichloride Chemical compound [Cl-].[Cl-].C1=C[N+](C)=CC=C1C1=CC=[N+](C)C=C1 FIKAKWIAUPDISJ-UHFFFAOYSA-L 0.000 description 2
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Abstract
Description
本発明は、光触媒として利用される酸化チタン粒子の結晶性評価方法、及び酸化チタン粒子の表面欠陥密度測定方法に関する。 The present invention relates to a method for evaluating crystallinity of titanium oxide particles used as a photocatalyst and a method for measuring the surface defect density of titanium oxide particles.
酸化チタン（ＴｉＯ２）粒子は、ペイント、化粧品、食品添加物における白色顔料として広く使用されてきた。その他に、酸化チタンが示す光触媒作用により、大気汚染の原因となる窒素酸化物（ＮＯｘ）の分解や水質汚濁を生じる有機溶剤の分解、環境ホルモンの分解、レジオネラ菌などの殺菌など、検討が行われている。中でもタバコなどに含まれる悪臭物質の一つであるアセトアルデヒドや酢酸成分を酸化チタン光触媒で分解する試みは広く実施されている（例えば、非特許文献１参照。）。 Titanium oxide (TiO 2 ) particles have been widely used as white pigments in paints, cosmetics and food additives. In addition, due to the photocatalytic action exhibited by titanium oxide, studies have been made on decomposition of nitrogen oxides (NOx) that cause air pollution, decomposition of organic solvents that cause water pollution, decomposition of environmental hormones, sterilization of Legionella bacteria, etc. It has been broken. In particular, attempts to decompose acetaldehyde and acetic acid components, which are one of malodorous substances contained in tobacco and the like, with a titanium oxide photocatalyst have been widely carried out (for example, see Non-Patent Document 1).
アセトアルデヒド、酢酸を酸化チタン光触媒で分解する場合、従来の酸化チタン粒子では、比表面積が大きいほど分解特性に優れている傾向があり、市販の光触媒を目的とする酸化チタン粒子では、少なくとも３０ｍ２／ｇ以上の粒子が主流である。これは分解対象物の吸着性能に優れるためである。 When decomposing acetaldehyde and acetic acid with a titanium oxide photocatalyst, the conventional titanium oxide particles tend to have superior decomposition characteristics as the specific surface area increases. With titanium oxide particles intended for commercial photocatalysts, at least 30 m 2 / Particles of g or more are mainstream. This is because the decomposition target object has excellent adsorption performance.
しかし、小粒径の酸化チタン粒子を製造するのは困難であり、また粒子自体の結晶性の低下により励起された電子・ホールの再結合が起こりやすくなり、量子効率の低下、光触媒活性の低下を招くという問題があった。 However, it is difficult to produce small-diameter titanium oxide particles, and recombination of excited electrons and holes is likely to occur due to a decrease in crystallinity of the particles themselves, resulting in a decrease in quantum efficiency and a decrease in photocatalytic activity. There was a problem of inviting.
本発明は前記事情に鑑みてなされ、従来の酸化チタン粒子に比べ結晶性が高く、光触媒作用による分解力に優れる酸化チタン粒子の結晶性評価方法、及び酸化チタン粒子の表面欠陥密度測定方法の提供を目的とする。 The present invention has been made in view of the above circumstances, and provides a method for evaluating the crystallinity of titanium oxide particles, which has higher crystallinity than conventional titanium oxide particles and has excellent decomposability due to photocatalysis, and a method for measuring the surface defect density of titanium oxide particles. With the goal.
前記目的を達成するため、本発明は、内径φ１５ｍｍの密閉容器に無酸素下で１０ｖｏｌ％トリエタノールアミン水溶液５ｍＬと酸化チタン粒子５０ｍｇを入れ、懸濁させた状態で波長３６５ｎｍの紫外光を照射することで測定される酸化チタン粒子表面に生成するＴｉ３＋密度が０．７μｍｏｌ／ｍ２以下であるか否かを評価することを特徴とする酸化チタン粒子の結晶性評価方法を提供する。
本発明の結晶性評価方法において、酸化チタン粒子は光触媒活性を有することが好ましい。
In order to achieve the above object, the present invention irradiates ultraviolet light with a wavelength of 365 nm in a suspended state in which 5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles are put in a sealed container having an inner diameter of 15 mm and suspended. There is provided a method for evaluating crystallinity of titanium oxide particles, characterized by evaluating whether or not the Ti 3+ density produced on the surface of the titanium oxide particles is 0.7 μmol / m 2 or less.
In the crystallinity evaluation method of the present invention, the titanium oxide particles preferably have photocatalytic activity.
また内径φ１５ｍｍの密閉容器に無酸素下で１０ｖｏｌ％トリエタノールアミン水溶液５ｍＬと酸化チタン粒子５０ｍｇを入れ、懸濁させた状態で波長３６５ｎｍの紫外光を照射することで測定される酸化チタン粒子表面に生成するＴｉ３＋密度が０．７μｍｏｌ／ｍ２以下であるか否かを測定することを特徴とする酸化チタン粒子の表面欠陥密度測定方法を提供する。 Further, 5 mL of 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles are put in an airtight container with an inner diameter of φ15 mm under anaerobic conditions, and the surface of the titanium oxide particles measured by irradiating ultraviolet light with a wavelength of 365 nm in a suspended state is applied. Provided is a method for measuring the surface defect density of titanium oxide particles, wherein it is determined whether or not the generated Ti 3+ density is 0.7 μmol / m 2 or less.
本発明の表面欠陥密度測定方法において、酸化チタン粒子は光触媒活性を有することが好ましい。 In the surface defect density measuring method of the present invention, the titanium oxide particles preferably have photocatalytic activity.
本発明の酸化チタン粒子は、結晶性が高く、電子・ホールの再結合が抑制され、高効率で光触媒作用を発揮し、光触媒として優れている。
本発明の酸化チタン粒子の製造方法は、結晶性が高く、電子・ホールの再結合が抑制され、高効率で光触媒作用を発揮し、光触媒として優れた酸化チタン粒子を効率よく製造することができる。
本発明の光触媒塗料は、前記本発明の酸化チタン粒子を含むものなので、高効率で光触媒作用を発揮する塗料を提供することができる。
本発明の汚染物質分解方法は、前記本発明に係る酸化チタン粒子に励起光照射下、汚染物質を接触させて該汚染物質を分解、浄化する構成なので、高効率で光触媒作用を発揮する本発明の酸化チタン粒子によって高効率で汚染物質を分解、浄化することができる。
The titanium oxide particles of the present invention have high crystallinity, suppress recombination of electrons and holes, exhibit photocatalytic action with high efficiency, and are excellent as photocatalysts.
The method for producing titanium oxide particles of the present invention has high crystallinity, suppresses recombination of electrons and holes, exhibits photocatalysis with high efficiency, and can efficiently produce titanium oxide particles excellent as a photocatalyst. .
Since the photocatalyst coating material of the present invention contains the titanium oxide particles of the present invention, it is possible to provide a coating material that exhibits a photocatalytic action with high efficiency.
The pollutant decomposition method of the present invention is configured to decompose and purify the pollutant by bringing the titanium oxide particles according to the present invention into contact with the pollutant under irradiation of excitation light, so that the present invention exhibits high efficiency photocatalysis. The titanium oxide particles can decompose and purify pollutants with high efficiency.
本発明の酸化チタン粒子は、結晶性が高く、酸化チタン粒子表面の欠陥密度が従来の市販の酸化チタン粒子に比べて少ないことを特徴としている。
非特許文献２に記載されているように、光触媒作用は酸化チタン粒子表面で起こるため、酸化チタン粒子表面のＴｉ３＋量を比較することで再結合中心となる欠陥量を比較することができ、結晶性の良し悪しを定義できる。Ｔｉ３＋量の比較は、次の方法で実施できる。内径φ１５ｍｍの密閉容器に無酸素下、例えば窒素やアルゴン雰囲気中で１０ｖｏｌ％トリエタノールアミン水溶液５ｍＬと酸化チタン粒子５０ｍｇを入れ、懸濁させた状態で波長３６５ｎｍの紫外光を１５ｍＷ／ｃｍ２の照度で十分な時間照射することで、欠陥サイト（Ｔｉ４＋）は還元されてＴｉ３＋となる。ここに１ｍｏｌ／Ｌメチルビオロゲン水溶液を５０μＬ添加すると、Ｔｉ３＋からＭＶ２＋に電子移動が起こり、Ｔｉ３＋と等量のＭＶ＋・ラジカルが生成し、溶液は青色を帯びるため、溶液の吸光度を測定することでＴｉ３＋量を算出することができる。
The titanium oxide particles of the present invention are characterized by high crystallinity and a lower defect density on the surface of the titanium oxide particles than conventional commercially available titanium oxide particles.
As described in
ここで算出されるＴｉ３＋量は酸化チタンの内部と表面に存在する欠陥量の和である。
前記の実験条件のように酸化チタン粒子重量を揃えて比較した場合、表面欠陥量は全欠陥量から内部欠陥量を差し引いたものであり、比表面積に比例する。前記の方法で市販の酸化チタン粒子（市販粒子１〜７）と本発明の酸化チタン粒子（本発明粒子）についてＴｉ３＋量を算出し、比表面積を横軸、Ｔｉ３＋量を縦軸にとったグラフを図２に示す。市販粒子と本発明の粒子のいずれの場合でも比表面積が０におけるＴｉ３＋量の外挿値はほぼ８μｍｏｌ／ｇであり、これが内部欠陥量に相当する。Ｔｉ３＋量からこの内部欠陥量を差し引いた表面欠陥量は、市販粒子と本発明の粒子のいずれの場合でも比表面積にほぼ比例して増大したが、その傾き、すなわち表面欠陥密度が市販粒子について１．２μｍｏｌ／ｍ２程度であるのに対し、本発明の粒子の酸化チタン粒子の表面欠陥密度は０．７μｍｏｌ／ｍ２以下であることを特徴としており、結晶性が非常に高い酸化チタン粒子であると言える。
The amount of Ti 3+ calculated here is the sum of the amount of defects existing inside and on the surface of titanium oxide.
When comparing the titanium oxide particles with the same weight as in the above experimental conditions, the surface defect amount is the total defect amount minus the internal defect amount, and is proportional to the specific surface area. The Ti 3+ amount was calculated for the commercially available titanium oxide particles (commercial particles 1 to 7) and the titanium oxide particles of the present invention (present particles) according to the above method, the specific surface area was plotted on the horizontal axis, and the Ti 3+ amount was plotted on the vertical axis. The graph is shown in FIG. In both cases of the commercially available particles and the particles of the present invention, the extrapolated value of the amount of Ti 3+ at a specific surface area of 0 is approximately 8 μmol / g, which corresponds to the amount of internal defects. The amount of surface defects obtained by subtracting the amount of internal defects from the amount of Ti 3+ increased almost in proportion to the specific surface area in both cases of the commercially available particles and the particles of the present invention. The surface defect density of the titanium oxide particles of the particles of the present invention is about 1.2 μmol / m 2 , whereas the surface defect density is 0.7 μmol / m 2 or less, and the titanium oxide particles have very high crystallinity. It can be said that.
これらの市販粒子と本発明粒子について、以下に示す方法で酢酸水溶液の分解により光触媒作用を比較してみた。内径φ１５ｍｍの密閉容器に５ｖｏｌ％酢酸水溶液５ｍＬと酸化チタン粒子５０ｍｇを入れ、懸濁させた状態で波長３６５ｎｍの紫外光を１５ｍＷ／ｃｍ２の照度で照射し、１時間あたりに発生する二酸化炭素（ＣＯ２）量で比較した。市販の酸化チタン粒子（市販サンプル１〜１０）と本発明粒子（１０面体粒子）とは、それぞれ図３に示す特性を示した。この実験条件では紫外線照射面積が一定であるため、酸化チタン粒子が受け取る励起光量が一定であり、分解量は分解対象物に対する吸着能で決定される。したがって市販粒子のような従来の酸化チタン粒子では、二酸化炭素の発生量は酸化チタン粒子の比表面積値に比例することが知られているが、本発明の酸化チタン粒子は結晶性が高く、電子・ホールの再結合を抑制し、高効率で光触媒作用を示すと考えられ、実際に分解実験を行った結果、同等の比表面積値の市販粒子に比べ２〜３倍の酢酸分解能を示した。 For these commercially available particles and the particles of the present invention, the photocatalytic action was compared by decomposing an acetic acid aqueous solution by the method described below. Carbon dioxide generated per hour by irradiating ultraviolet light with a wavelength of 365 nm with an illuminance of 15 mW / cm 2 in a suspended state with 5 mL of 5 vol% acetic acid aqueous solution and 50 mg of titanium oxide particles in a sealed container with an inner diameter of 15 mm. Comparison was made by the amount of CO 2 ). Commercially available titanium oxide particles (commercial samples 1 to 10) and the present invention particles (decahedral particles) exhibited the characteristics shown in FIG. Since the ultraviolet irradiation area is constant under this experimental condition, the amount of excitation light received by the titanium oxide particles is constant, and the amount of decomposition is determined by the ability to adsorb to the decomposition target. Therefore, in conventional titanium oxide particles such as commercially available particles, it is known that the amount of carbon dioxide generated is proportional to the specific surface area value of the titanium oxide particles, but the titanium oxide particles of the present invention have high crystallinity, -The recombination of holes is suppressed, and it is considered that the photocatalytic action is exhibited with high efficiency. As a result of actual decomposition experiments, the acetic acid resolution was 2 to 3 times that of commercially available particles having an equivalent specific surface area value.
次に、本発明の酸化チタン粒子の製造方法について説明する。
図１は本発明の製造方法において好適に用いられる酸化チタン粒子製造装置を例示する構成図であり、図１中符号１は石英ガラス管、２は酸水素バーナー、３及び４は配管、５はチタン化合物、６はバグフィルター、７はバブラーである。
反応合成管となる石英ガラス管１の下方には酸水素バーナー２が設けられている。この石英ガラス管１の入口側には、チタン化合物５を入れたバブラー７に接続されてＡｒガスとともに気化したチタン化合物５が供給される管路３と、酸素源から酸素（Ｏ２）を供給する管路４が接続されている。また石英ガラス管１の出口側は、生成した酸化チタン粒子を捕集するためのバグフィルター６を介して排気系に接続されている。
Next, the manufacturing method of the titanium oxide particle of this invention is demonstrated.
FIG. 1 is a configuration diagram illustrating a titanium oxide particle production apparatus suitably used in the production method of the present invention. In FIG. 1, reference numeral 1 is a quartz glass tube, 2 is an oxyhydrogen burner, 3 and 4 are piping, Titanium compound, 6 is a bag filter, and 7 is a bubbler.
An
原料としては、四塩化チタン（ＴｉＣｌ４）などのチタン化合物を用い、バブリングもしくはベイキングによって気相供給できる。原料は反応酸素と合流させ、反応合成管である石英ガラス管１に導入する。この原料には、可視光励起可能な光触媒の製造や分解力の調整を目的として、酸化チタンに、例えばＰ，Ｎ，Ｓｉ，Ｂなどのドーパントを添加することができる。ドーパントを添加する場合、原料とドーパントを配管中で合流させ、石英ガラス管１に導入することができる。 As a raw material, a titanium compound such as titanium tetrachloride (TiCl 4 ) is used, and gas phase supply can be performed by bubbling or baking. The raw material is combined with the reaction oxygen and introduced into the quartz glass tube 1 which is a reaction synthesis tube. To this raw material, a dopant such as P, N, Si, or B can be added to titanium oxide for the purpose of producing a photocatalyst that can be excited by visible light and adjusting the decomposition power. When the dopant is added, the raw material and the dopant can be merged in the pipe and introduced into the quartz glass tube 1.
原料及び反応酸素を石英ガラス管１に導入し、この石英ガラス管１を外部より酸水素バーナー２の火炎で熱し、反応熱を与えることで酸化チタン粒子を合成する。例えば、四塩化チタンを原料に用いた場合、合成温度８５０℃以上で９０％以上の反応率となる。また合成温度１５００℃以上では、酸化チタン粒子の焼結が始まって、粒子の比表面積が小さくなるため、合成温度８５０〜１５００℃の範囲内で合成を行うことが望ましい。本例示では反応合成管として石英ガラス管１を用いているが、熱的及び化学的に安定な他の材料、例えばアルミナのような熱的及び化学的に安定な材質のチューブであれば利用可能である。反応合成管のサイズは、合成管内径がφ５０ｍｍ以上であると反応合成管内部の径方向温度分布が大きくなり、酸化チタン粒子の粒径分布が大きくなるので望ましくない。また反応合成管の内径が小さいと管内流速が速くなり、反応効率が落ちるので、反応合成管の内径はφ１０ｍｍ以上が望ましい。また、原料及び反応酸素量を減らして管内流速を遅くすると、合成量が落ち、工業的に望ましくない。
Raw materials and reactive oxygen are introduced into the quartz glass tube 1, the quartz glass tube 1 is heated from the outside with a flame of an
反応合成管内の原料及び反応酸素の流速が速い方がヒートゾーン通過にかかる時間、すなわち結晶成長する時間が短くなり、粒径の小さな酸化チタン粒子を得ることができる。
しかし、流速が速くなりすぎると、反応効率が大幅に落ちるので、工業的に望ましくない。四塩化チタンを原料に用い、φ３２ｍｍ×２．５ｔの石英ガラス管を反応合成管に用い、合成温度を１２３０℃に設定した場合、流速１５０〜１５００ｍｍ／ｍｉｎの範囲内とするのが望ましい。
When the flow rates of the raw material and reaction oxygen in the reaction synthesis tube are higher, the time required for passing through the heat zone, that is, the time for crystal growth, is shortened, and titanium oxide particles having a small particle diameter can be obtained.
However, if the flow rate is too high, the reaction efficiency is greatly reduced, which is not industrially desirable. When titanium tetrachloride is used as a raw material, a quartz glass tube having a diameter of 32 mm × 2.5 t is used as a reaction synthesis tube, and the synthesis temperature is set to 1230 ° C., the flow rate is preferably in the range of 150 to 1500 mm / min.
前記例示では酸水素バーナー２を反応熱源に用いているが、酸水素バーナー２は発生熱量が高く、電気ヒーターに比べ、局所的な加熱が可能である。そのため、均一核生成に必要な熱エネルギーを容易に与えることができ、また、ヒートゾーンが狭くなることも加わり、酸化チタンの結晶成長を抑制することができる。また容易に原子の拡散移動に必要な高温を得ることができ、結晶性の高い酸化チタン粒子を合成することができる。
In the above example, the
また、石英ガラス管１をガラス旋盤に固定し、回転させることで周方向の温度分布を小さくできる。回転速度は２０〜７０ｒｐｍが望ましい。 Further, the temperature distribution in the circumferential direction can be reduced by fixing the quartz glass tube 1 to a glass lathe and rotating it. The rotation speed is preferably 20 to 70 rpm.
合成した酸化チタン粒子を回収する方法としては、ターゲットへの堆積や、フィルターでの回収が適している。ターゲットへの堆積方法は、サーモフォレシス効果を利用し、反応合成管として用いた石英ガラス管１の下流部分に付着させる方法が有効である。石英ガラス管１の合成部分は、１０００℃程度まで局所的に加熱されており、下流の加熱されていない部分は数十℃程度であり、効果的にサーモフォレシス効果が作用するので適している。また、堆積部分を水、または窒素などの気体で冷却すると、さらに堆積効率は高くなる。さらに、熱交換作用の大きなＨｅガスを原料及び反応酸素に混合すると、サーモフォレシス効果が高まり、堆積効率が高くなる。 As a method for recovering the synthesized titanium oxide particles, deposition on a target or recovery with a filter is suitable. As a deposition method on the target, a method of using the thermophoresis effect and adhering to the downstream portion of the quartz glass tube 1 used as a reaction synthesis tube is effective. The synthetic part of the quartz glass tube 1 is locally heated to about 1000 ° C., and the downstream unheated part is about several tens of degrees C. This is suitable because the thermophoresis effect acts effectively. Further, when the deposited portion is cooled with water or a gas such as nitrogen, the deposition efficiency is further increased. Furthermore, when a He gas having a large heat exchange action is mixed with the raw material and reactive oxygen, the thermophoresis effect is enhanced and the deposition efficiency is increased.
フィルターでの回収方法は、合成される酸化チタン微粒子の粒径が数ｎｍ〜数十ｎｍ程度であり、フィルターは目詰まりを起こしやすい。そのため、例えば、圧縮ガス（空気、窒素など）でフィルターに衝撃を与えて目詰まりした粒子を払い落とす機構を備えたバグフィルターや、機械的に目詰まりを叩き落とす機構を備えたバグフィルターを用いることが目詰まり対策に効果的である。また、前記サーモフォレシス効果による堆積とバグフィルターによる捕集とを直列に配置して、両方で酸化チタン粒子を回収すると、高い回収効率が得られるので望ましい。 In the recovery method using a filter, the titanium oxide fine particles to be synthesized have a particle size of about several nanometers to several tens of nanometers, and the filter is easily clogged. For this reason, for example, a bag filter having a mechanism that blows off clogged particles by impacting the filter with compressed gas (air, nitrogen, etc.) or a bag filter having a mechanism that mechanically knocks off the clogging is used. This is an effective countermeasure against clogging. In addition, it is desirable that the deposition by the thermophoresis effect and the collection by the bag filter are arranged in series and the titanium oxide particles are collected by both, because high collection efficiency can be obtained.
この製造方法で得られる酸化チタン粒子の結晶系はアナターゼ型であり、（００１）面と（１０１）面からなる１０面体構造をとることを特徴としている。 The crystal system of the titanium oxide particles obtained by this production method is anatase type, and is characterized by taking a decahedron structure composed of (001) plane and (101) plane.
本発明はまた、前述した本発明に係る酸化チタン粒子を含む光触媒塗料を提供する。この光触媒塗料は、前記酸化チタン粒子と、塗料成分として従来公知のバインダーや溶剤、その他の適当な添加成分を加えて調製することができ、配合するバインダー樹脂や溶剤の種類によって水性塗料、油性塗料などとすることができる。この光触媒塗料は、該塗料を被塗装面に塗布し、得られる乾燥塗膜表面に光触媒として必要十分な量の前記酸化チタン粒子が存在するように酸化チタン粒子の配合量を設定することが望ましい。本発明の光触媒塗料は、前記本発明の酸化チタン粒子を含むものなので、高効率で光触媒作用を発揮する塗膜を形成することができる。 The present invention also provides a photocatalytic coating comprising the titanium oxide particles according to the present invention described above. This photocatalyst paint can be prepared by adding the titanium oxide particles and a conventionally known binder or solvent as a paint component, and other appropriate additive components. A water-based paint or an oil-based paint can be used depending on the type of binder resin or solvent to be blended. And so on. In this photocatalyst coating, it is desirable to apply the coating to the surface to be coated, and to set the blending amount of the titanium oxide particles so that the titanium oxide particles necessary and sufficient as the photocatalyst are present on the surface of the resulting dried coating film. . Since the photocatalyst coating material of the present invention contains the titanium oxide particles of the present invention, it is possible to form a coating film that exhibits a photocatalytic action with high efficiency.
本発明はまた、本発明の汚染物質分解方法は、前記本発明に係る酸化チタン粒子に励起光照射下、汚染物質を接触させて該汚染物質を分解、浄化する汚染物質分解方法を提供する。この汚染物質分解方法において分解可能な汚染物質としては、水（排水等）や空気などの流体に含まれる各種の汚染物質が挙げられ、例えば、窒素酸化物（ＮＯｘ）の分解や水質汚濁を生じる有機溶剤の分解、環境ホルモンの分解、レジオネラ菌などの殺菌、ウイルスの分解などが挙げられる。酸化チタン粒子に励起光照射下、汚染物質を接触させるための装置構成は限定されず、例えば、酸化チタン粒子を含む塗膜を形成した多数のフィンや管などの基材に紫外光などの励起光を照射しながら汚染物質を含む流体を流す構造や、部分的に漏光するように加工した光ファイバの表面に酸化チタン粒子を塗布し、この光ファイバに紫外光などの励起光を入射しつつ表面の酸化チタン塗膜に汚染物質を含む流体を接触させる構造などが好ましい。本発明の汚染物質分解方法は、高効率で光触媒作用を発揮する本発明の酸化チタン粒子によって高効率で汚染物質を分解、浄化することができる。 The present invention also provides a pollutant decomposition method of the present invention, in which a contaminant is brought into contact with titanium oxide particles according to the present invention under excitation light irradiation to decompose and purify the contaminant. Examples of pollutants that can be decomposed by this pollutant decomposition method include various pollutants contained in fluids such as water (drainage, etc.) and air. For example, nitrogen oxide (NOx) decomposition and water pollution occur. Examples include decomposition of organic solvents, decomposition of environmental hormones, sterilization of Legionella bacteria, and virus decomposition. There is no limitation on the configuration of the apparatus for bringing the titanium oxide particles into contact with the pollutant under excitation light irradiation. For example, excitation of ultraviolet light or the like on a substrate such as a large number of fins or tubes formed with a coating film containing titanium oxide particles. Titanium oxide particles are applied to the surface of an optical fiber that is made to flow a fluid containing pollutants while irradiating light, or is partially leaked, and excitation light such as ultraviolet light is incident on this optical fiber. A structure in which a fluid containing a contaminant is brought into contact with the surface titanium oxide coating film is preferable. The pollutant decomposition method of the present invention can decompose and purify pollutants with high efficiency by the titanium oxide particles of the present invention that exhibit photocatalysis with high efficiency.
［実施例１］
ガラス旋盤にφ４０ｍｍの石英ガラス管を設置し、４５ｒｐｍで回転させた。そこに四塩化チタン蒸気５０ｓｃｃｍと酸素１２００ｓｃｃｍを導入し、石英ガラス管の外部から酸水素バーナー炎で１３００℃で加熱し、酸化チタン粒子を合成した。合成した酸化チタン粒子はバグフィルターで回収した。回収した酸化チタンは１０面体形状であり、ＢＥＴ法により比表面積を測定したところ、１０．２ｍ２／ｇであった。
[Example 1]
A quartz glass tube with a diameter of 40 mm was placed on a glass lathe and rotated at 45 rpm. The titanium tetrachloride vapor | steam and oxygen 1200sccm were introduce | transduced there, and it heated at 1300 degreeC with the oxyhydrogen burner flame from the exterior of the quartz glass tube, and synthesize | combined the titanium oxide particle. The synthesized titanium oxide particles were collected with a bag filter. The recovered titanium oxide had a icosahedral shape, and the specific surface area measured by the BET method was 10.2 m 2 / g.
［実施例２］
ガラス旋盤にφ４０ｍｍの石英ガラス管を設置し、４５ｒｐｍで回転させた。そこに四塩化チタン蒸気２０ｓｃｃｍと酸素１２００ｓｃｃｍを導入し、石英ガラス管の外部から酸水素バーナー炎で１３００℃で加熱し、酸化チタン粒子を合成した。合成した酸化チタン粒子はバグフィルターで回収した。回収した酸化チタンは１０面体形状であり、ＢＥＴ法により比表面積を測定したところ、３２．４ｍ２／ｇであった。
[Example 2]
A quartz glass tube with a diameter of 40 mm was placed on a glass lathe and rotated at 45 rpm.
［実施例３及び比較例１］
実施例１及び２で得られた酸化チタン粒子と、合成温度条件とガス条件を変更し、同様の製法で得られた４種、合計６種の酸化チタン粒子（本発明粒子１〜６）について結晶性の評価を行った。ＳＥＭとＸＲＤで確認したところ、これらの本発明粒子１〜６は１０面体形状のアナターゼ型酸化チタン粒子からなることを確認した。
また市販の酸化チタン粒子（市販粒子１〜８）についても、結晶性の評価を行い比較した。内径φ１５ｍｍの密閉容器に窒素雰囲気下で１０ｖｏｌ％トリエタノールアミン水溶液５ｍＬと酸化チタン粒子５０ｍｇを入れ、懸濁させた状態で波長３６５ｎｍの紫外光を１５ｍＷ／ｃｍ２の照度で４８時間照射した。ここに１ｍｏｌ／Ｌメチルビオロゲン水溶液を５０μＬ添加し、酸化チタン粒子を遠心分離した後、溶液の６０６ｎｍにおける吸光度を測定した。ＭＶ＋・ラジカルの吸光係数を１３７００ｍｏｌ−１Ｌｃｍ−１とし、酸化チタン粒子表面のＴｉ３＋密度を算出し比較した。結果を表１に示す。
[Example 3 and Comparative Example 1]
About the titanium oxide particles obtained in Examples 1 and 2, the synthesis temperature condition and the gas condition, 4 types obtained by the same production method, a total of 6 types of titanium oxide particles (present particles 1 to 6) Crystallinity was evaluated. As a result of confirmation by SEM and XRD, it was confirmed that these particles 1 to 6 of the present invention consisted of decahedral anatase-type titanium oxide particles.
In addition, the crystallinity of the commercially available titanium oxide particles (commercial particles 1 to 8) was also evaluated and compared. In a nitrogen atmosphere, 5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles were placed in a sealed container having an inner diameter of 15 mm, and irradiated with ultraviolet light having a wavelength of 365 nm at an illuminance of 15 mW / cm 2 for 48 hours. 50 μL of a 1 mol / L methyl viologen aqueous solution was added thereto, the titanium oxide particles were centrifuged, and the absorbance of the solution at 606 nm was measured. An extinction coefficient of MV + · radicals and 13700mol -1 Lcm -1, were compared to calculate the Ti 3+ density of the titanium oxide particle surfaces. The results are shown in Table 1.
表１から、市販粒子１〜８の表面欠陥密度は１．２μｍｏｌ／ｍ２程度であるのに対し、本発明粒子１〜６の表面欠陥密度は０．７μｍｏｌ／ｍ２以下となった。 From Table 1, the surface defect density of the commercially available particles 1 to 8 is about 1.2 μmol / m 2 , whereas the surface defect density of the present particles 1 to 6 is 0.7 μmol / m 2 or less.
［実施例４及び比較例２］
実施例１及び２で得られた酸化チタン粒子と、合成温度条件とガス条件を変更し、同様の製法で得られた２種、合計４種の酸化チタン粒子と市販の酸化チタン粒子について酢酸分解を行い、光触媒作用を比較した。それぞれの酸化チタン粒子５０ｍｇを内径φ１５ｍｍの密閉容器に入れ、５ｖｏｌ％酢酸水溶液５ｍＬに懸濁させ、懸濁させた状態で波長３６５ｎｍの紫外光を１５ｍＷ／ｃｍ２の照度で照射し、１時間あたりに発生する二酸化炭素（ＣＯ２）量をガスクロマトグラフィーで定量した。横軸に比表面積、縦軸に二酸化炭素発生速度をとったグラフを図３に示す。なお、図３において、本発明の４種類の粒子は「●１０面体粒子」としてプロットし、市販の酸化チタン粒子は「□市販サンプル１〜１０」としてプロットしてある。
図３のグラフから、本発明の酸化チタン粒子は、同等の比表面積値の市販粒子に比べ、２〜３倍の酢酸分解能を有することがわかる。
[Example 4 and Comparative Example 2]
The titanium oxide particles obtained in Examples 1 and 2, the synthesis temperature condition and the gas condition were changed, and two types obtained by the same production method, a total of four types of titanium oxide particles and commercially available titanium oxide particles were decomposed with acetic acid. The photocatalytic action was compared. 50 mg of each titanium oxide particle was placed in a sealed container having an inner diameter of 15 mm, suspended in 5 mL of a 5 vol% acetic acid aqueous solution, and irradiated with ultraviolet light having a wavelength of 365 nm at an illuminance of 15 mW / cm 2 per hour. The amount of carbon dioxide (CO 2 ) generated in the gas was determined by gas chromatography. FIG. 3 is a graph in which the horizontal axis represents the specific surface area and the vertical axis represents the carbon dioxide generation rate. In FIG. 3, the four types of particles of the present invention are plotted as “• 10-hedral particles”, and the commercially available titanium oxide particles are plotted as “□ commercial samples 1 to 10”.
From the graph of FIG. 3, it can be seen that the titanium oxide particles of the present invention have an acetic acid resolution of 2 to 3 times that of commercially available particles having an equivalent specific surface area value.
１…石英ガラス管（反応合成管）、２…酸水素バーナー、３，４…配管、５…チタン化合物、６…バグフィルター、７…バブラー。 DESCRIPTION OF SYMBOLS 1 ... Quartz glass tube (reaction synthesis tube), 2 ... Oxyhydrogen burner, 3, 4 ... Piping, 5 ... Titanium compound, 6 ... Bag filter, 7 ... Bubbler.
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| JP2008303126A (en) * | 2007-06-11 | 2008-12-18 | Showa Denko Kk | Method for production of titanium oxide particles |
| US8178074B2 (en) | 2008-08-29 | 2012-05-15 | Showa Denko K.K. | Method for producing titanium oxide particles |
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