JP6899585B2 - Visible light active photocatalyst composite filter material, its manufacturing method - Google Patents
Visible light active photocatalyst composite filter material, its manufacturing method Download PDFInfo
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Description
本発明は、可視光領域で活性が発現できる光触媒複合フィルター材やその製造方法に関する。 The present invention relates to a photocatalytic composite filter material capable of exhibiting activity in the visible light region and a method for producing the same.
光触媒は省エネで環境にやさしい技術であるため、種々の工業用途だけでなく、特に生活環境の改善への実用化が有望視されている。しかし、光触媒は通常一般的な熱触媒と比べ反応速度が遅いために、環境浄化や生活環境への応用に際しては、比較的汚染負荷が小さい系や、ある程度綺麗にした環境をさらにより良くするなど、範囲が限られているという面もある。 Since photocatalyst is an energy-saving and environmentally friendly technology, it is expected to be put into practical use not only for various industrial applications but also for improving the living environment. However, since photocatalysts usually have a slower reaction rate than general thermal catalysts, when purifying the environment or applying it to the living environment, it is possible to improve the system with a relatively small pollution load or a clean environment to some extent. There is also the aspect that the range is limited.
このような従来技術の中で、チタニアなどの光触媒粒子をガラス、石英、メソ多孔材料、ステンレス鋼、ポリマー等の基材中に分散・担持して、抗菌性生地や光触媒膜反応器として応用することが提案されている（非特許文献１）。しかしながら、このような応用に際しては、チタニアなどの紫外線活性の触媒粒子を用い、紫外線照射下で反応を進行させるものであった。 In such a conventional technique, photocatalytic particles such as titania are dispersed and supported in a substrate such as glass, quartz, mesoporous material, stainless steel, or polymer, and applied as an antibacterial fabric or a photocatalytic membrane reactor. Has been proposed (Non-Patent Document 1). However, in such an application, the reaction is allowed to proceed under ultraviolet irradiation by using ultraviolet-active catalyst particles such as titania.
上述のようなチタニアなどの光触媒粒子をガラス、石英、メソ多孔材料、ステンレス鋼、ポリマー等の基材中に分散・担持して、抗菌性生地や光触媒膜反応器とするものについて、本発明者は調査、検討したが、次の（１）〜（３）のような欠点を有していることを認識した。
（１）紫外線照射に加え、比較的強い光触媒活性が生じるために繊維質などの基質材が比較的傷みやすく、フィルター材の寿命が短くなってしまう。
（２）繊維質などによる光散乱のために紫外線はフィルター材の内部まで浸透しにくく、折角フィルター材の内部に光触媒粒子を頑丈に固定していても表面しか光触媒反応が発生しない可能性があり、また、これを克服するためには光触媒粒子表面層を形成する解決法も考えられるが、表面層における光触媒粒子の固定は難点である。
（３）光触媒粒子をフィルター材のマトリクス中に組み込み、固定しているために、水中における応用に際しては光触媒自体による水流阻害を検討する必要がある。このような複合フィルター材を光照射下においてアンチファウリング性を持つ種々の水処理用膜の表面層として使えるが、その光触媒反応が十分でない場合には、バクテリア等の汚染による水流阻害が起こり、水流フラックスの減少がより大きな問題点となる。
The present inventor provides an antibacterial fabric or a photocatalytic membrane reactor in which photocatalytic particles such as titania as described above are dispersed and supported in a base material such as glass, quartz, mesoporous material, stainless steel, or polymer. Investigated and examined, but recognized that it had the following drawbacks (1) to (3).
(1) In addition to ultraviolet irradiation, relatively strong photocatalytic activity is generated, so that the substrate material such as fiber is relatively easily damaged, and the life of the filter material is shortened.
(2) Ultraviolet rays do not easily penetrate into the filter material due to light scattering due to fibers, etc., and even if the photocatalytic particles are firmly fixed inside the filter material, the photocatalytic reaction may occur only on the surface. In addition, in order to overcome this, a solution for forming a photocatalyst particle surface layer can be considered, but fixing the photocatalyst particles on the surface layer is a drawback.
(3) Since the photocatalyst particles are incorporated and fixed in the matrix of the filter material, it is necessary to study the water flow inhibition by the photocatalyst itself when applying it in water. Such a composite filter material can be used as a surface layer of various water treatment membranes having antifouling properties under light irradiation, but if the photocatalytic reaction is not sufficient, water flow inhibition due to contamination with bacteria or the like occurs. The reduction of water flow flux becomes a bigger problem.
本発明は、上述のような従来技術や本発明者が認識した従来技術の欠点などを背景としたものであり、可視光領域で活性が比較的高く、バクテリア等の汚染や汚染等による流量低下が比較的少ない光触媒複合フィルター材を提供することを課題とする。 The present invention is based on the above-mentioned drawbacks of the prior art and the prior art recognized by the present inventor. The activity is relatively high in the visible light region, and the flow rate is reduced due to contamination by bacteria or the like. It is an object of the present invention to provide a photocatalyst composite filter material having a relatively small amount of water.
前記課題の下、各種の試験研究を進める過程で、本発明者は、先に、炭素粒子表面にチタニアを有する炭素粒子・チタニアコアシェル複合体が優れた可視光活性を発現できることを知見した。
そして、そのような炭素粒子・チタニアコアシェル複合体の応用について検討を進める過程で、セルロースナノファイバーからなるフィルター材に炭素粒子・チタニアコアシェル複合体を複合させることにより可視光領域での活性が比較的高く、バクテリア等の汚染や汚染等による流量低下が比較的少ないフィルター材が得られることを知見した。
In the process of proceeding with various test studies under the above-mentioned problems, the present inventor has previously discovered that a carbon particle-titania core-shell complex having titania on the surface of carbon particles can exhibit excellent visible light activity.
Then, in the process of studying the application of such a carbon particle-titania core-shell complex, the activity in the visible light region is relatively high by combining the carbon particle-titania core-shell complex with a filter material made of cellulose nanofibers. It was found that a filter material that is high and has a relatively small decrease in flow rate due to contamination with bacteria or the like can be obtained.
本発明は、上記のような知見に基づいて完成に至ったものであり、本件では、以下の発明が提供される。
＜１＞セルロースナノファイバー(以下、「CNF」ということがある。)と、該CNFに混合された光触媒を含む光触媒複合フィルター材であって、前記光触媒は炭素粒子・チタニアコアシェル複合体である光触媒複合フィルター材。
＜２＞前記光触媒と前記CNFは、重量割合が10:1〜1:10である＜１＞に記載の光触媒複合フィルター材。
＜３＞前記炭素粒子・チタニアコアシェル複合体は、ゼータ電位が-35mV以下又はC-OH/C-O-Cのモル比が30モル％以上で、かつ、C=Oのモル比が10モル％以下である修飾炭素粒子と、その表面に形成されたチタニアを含むものである＜１＞又は＜２＞に記載の光触媒複合フィルター材。
＜４＞炭素粒子・チタニアコアシェル複合体を分散した分散液にCNF懸濁液を添加、混合し、該混合液をろ過膜でろ過することを含む光触媒複合フィルター材の製造方法。
＜５＞＜４＞に記載の光触媒複合フィルター材の製造方法において、有機チタン化合物と炭素粒子を含む混合物を140〜250℃の温度で水熱処理し、前記炭素粒子・チタニアコアシェル複合体を製造することを含む光触媒複合フィルター材の製造方法。
＜６＞前記混合物は有機溶媒と水を含むものである＜５＞に記載の光触媒複合フィルター材の製造方法。
＜７＞ 前記有機チタン化合物が、チタンアルコキシド、チタンアシレート、チタンキレートから選択されるものである＜５＞又は＜６＞に記載の光触媒複合フィルター材の製造方法。
＜８＞前記有機溶媒がアルコール類、エーテル類、ケトン類、ニトリル類、カルボン酸類から選択されるものである＜６＞又は＜７＞に記載の光触媒複合フィルター材の製造方法。
＜９＞＜５＞に記載の光触媒複合フィルター材の製造方法において、糖類及び／又は糖類誘導体と不飽和脂肪酸を含む混合物を水熱処理して前記炭素粒子を製造することを含む光触媒複合フィルター材の製造方法。
＜１０＞前記不飽和脂肪酸は、糖類と糖類誘導体合計量の20〜150wt％である＜９＞に記載の光触媒複合フィルター材の製造方法。
The present invention has been completed based on the above findings, and the following inventions are provided in this case.
<1> A photocatalyst composite filter material containing cellulose nanofibers (hereinafter sometimes referred to as “CNF”) and a photocatalyst mixed with the CNF, wherein the photocatalyst is a photocatalyst which is a carbon particle / titania core shell composite. Composite filter material.
<2> The photocatalyst composite filter material according to <1>, wherein the photocatalyst and the CNF have a weight ratio of 10: 1 to 1:10.
<3> The carbon particle-titania core-shell complex has a zeta potential of −35 mV or less, a C-OH / COC molar ratio of 30 mol% or more, and a C = O molar ratio of 10 mol% or less. The photocatalytic composite filter material according to <1> or <2>, which contains modified carbon particles and titania formed on the surface thereof.
<4> A method for producing a photocatalytic composite filter material, which comprises adding and mixing a CNF suspension to a dispersion liquid in which a carbon particle / titania core-shell composite is dispersed, and filtering the mixed liquid with a filtration membrane.
In the method for producing a photocatalytic composite filter material according to <5> and <4>, a mixture containing an organic titanium compound and carbon particles is hydrothermally treated at a temperature of 140 to 250 ° C. to produce the carbon particle-titania core shell composite. A method for producing a photocatalytic composite filter material including the above.
<6> The method for producing a photocatalytic composite filter material according to <5>, wherein the mixture contains an organic solvent and water.
<7> The method for producing a photocatalyst composite filter material according to <5> or <6>, wherein the organic titanium compound is selected from titanium alkoxide, titanium acylate, and titanium chelate.
<8> The method for producing a photocatalytic composite filter material according to <6> or <7>, wherein the organic solvent is selected from alcohols, ethers, ketones, nitriles, and carboxylic acids.
<9> In the method for producing a photocatalytic composite filter material according to <5>, the photocatalytic composite filter material comprising producing the carbon particles by hydrothermally treating a mixture containing a saccharide and / or a saccharide derivative and an unsaturated fatty acid. Production method.
<10> The method for producing a photocatalytic composite filter material according to <9>, wherein the unsaturated fatty acid is 20 to 150 wt% of the total amount of the saccharide and the saccharide derivative.
本発明は、次のような実施態様を含むことができる。
＜１１＞前記炭素粒子・チタニアコアシェル複合体のチタニアの平均膜厚が1nm以上である＜１＞〜＜３＞のいずれか１項に記載の光触媒複合フィルター材。
＜１２＞前記炭素粒子・チタニアコアシェル複合体の炭素粒子が炭素球である＜４＞〜＜１０＞のいずれか１項に記載の光触媒複合フィルター材の製造方法。
＜１３＞水熱温度が150〜220℃である＜５＞〜＜１０＞のいずれか１項に記載の光触媒複合フィルター材の製造方法。
＜１４＞前記混合物中における有機チタン化合物のチタンと炭素粒子の炭素との重量比が12:1〜50:1である＜５＞〜＜８＞のいずれか１項に記載の光触媒複合フィルター材の製造方法。
＜１５＞前記混合物中における有機チタン化合物のチタンと炭素粒子の炭素との重量比が12:1〜40:1である＜１４＞に記載の光触媒複合フィルター材の製造方法。
＜１６＞ 前記混合物中における有機溶媒と水の体積比が8:1〜50:1である＜５＞〜＜８＞のいずれか１項に記載の光触媒複合フィルター材の製造方法。
＜１７＞前記混合物中における有機溶媒と水の体積比が10:1〜30:1である＜１６＞に記載の光触媒複合フィルター材の製造方法。
＜１８＞前記糖類は、ブドウ糖、果糖、スクロースから選択される１種又は２種以上である＜９＞又は＜１０＞に記載の光触媒複合フィルター材の製造方法。
＜１９＞＜１６＞前記不飽和脂肪酸は、アクリル酸、クロトン酸、オレイン酸、ソルビン酸、メタクリル酸、ソルビン酸から選択される１種又は２種以上である＜９＞、＜１０＞、＜１８＞のいずれか１項に記載の光触媒複合フィルター材の製造方法。
The present invention can include the following embodiments.
<11> The photocatalytic composite filter material according to any one of <1> to <3>, wherein the average film thickness of titania in the carbon particle-titania core-shell composite is 1 nm or more.
<12> The method for producing a photocatalyst composite filter material according to any one of <4> to <10>, wherein the carbon particles of the carbon particle-titania core-shell composite are carbon spheres.
<13> The method for producing a photocatalyst composite filter material according to any one of <5> to <10>, wherein the water heat temperature is 150 to 220 ° C.
<14> The photocatalytic composite filter material according to any one of <5> to <8>, wherein the weight ratio of titanium of the organic titanium compound to carbon of carbon particles in the mixture is 12: 1 to 50: 1. Manufacturing method.
<15> The method for producing a photocatalytic composite filter material according to <14>, wherein the weight ratio of titanium of the organic titanium compound to carbon of carbon particles in the mixture is 12: 1 to 40: 1.
<16> The method for producing a photocatalyst composite filter material according to any one of <5> to <8>, wherein the volume ratio of the organic solvent to water in the mixture is 8: 1 to 50: 1.
<17> The method for producing a photocatalytic composite filter material according to <16>, wherein the volume ratio of the organic solvent to water in the mixture is 10: 1 to 30: 1.
<18> The method for producing a photocatalytic composite filter material according to <9> or <10>, wherein the saccharide is one or more selected from glucose, fructose, and sucrose.
<19><16> The unsaturated fatty acid is one or more selected from acrylic acid, crotonic acid, oleic acid, sorbic acid, methacrylic acid, and sorbic acid <9>, <10>, <18> The method for producing a photocatalyst composite filter material according to any one of.
本発明の光触媒複合フィルター材は、可視光領域での活性が比較的高く、バクテリア等の汚染や汚染等による流量低下が比較的少ない。 The photocatalytic composite filter material of the present invention has relatively high activity in the visible light region, and the flow rate decrease due to contamination by bacteria or the like is relatively small.
以下、本発明を実施するための形態を説明する。
なお、本明細書において数値範囲を示す「〜」は、その前後に記載される数値を下限値及び上限値として含む意味として使用される。
本明細書で使用する主な略号とその意味は、次のとおりである。
AA：アクリル酸
CNF：セルロースナノファイバー
CNF-（光触媒）：（光触媒）複合セルロースナノファイバーフィルター材
CS：炭素球（球状の炭素粒子）
CS-xAA：スクロースに対しxwt％のアクリル酸で修飾された炭素球
DI：脱イオン
HPLC：高速液体クロマトグラフィー
TiO2@CS：炭素球・チタニアコアシェル複合体
TiO2@CS-xAA：スクロースに対しxwt％のアクリル酸で修飾された炭素球・チタニアコアシェル複合体
Hereinafter, modes for carrying out the present invention will be described.
In addition, in this specification, "~" indicating a numerical range is used as a meaning including numerical values described before and after the numerical range as a lower limit value and an upper limit value.
The main abbreviations used herein and their meanings are as follows.
AA: Acrylic acid
CNF: Cellulose nanofibers
CNF- (photocatalyst): (photocatalyst) composite cellulose nanofiber filter material
CS: Carbon sphere (spherical carbon particles)
CS-xAA: Carbon spheres modified with xwt% acrylic acid relative to sucrose
DI: Deionization
HPLC: High Performance Liquid Chromatography
TiO 2 @CS: Carbon Sphere / Titanium Core Shell Complex
TiO 2 @ CS-xAA: Carbon sphere-titanium core-shell complex modified with xwt% acrylic acid relative to sucrose
本発明の可視光活性を有する光触媒複合フィルター材は、セルロースナノファイバー(CNF)のマトリックス中に炭素粒子・チタニアコアシェル複合体からなる可視光活性光触媒を有するものである。 The photocatalyst composite filter material having visible light activity of the present invention has a visible light activated photocatalyst composed of a carbon particle / titania core shell composite in a matrix of cellulose nanofibers (CNF).
本発明においてCNFとは、繊維径がナノサイズ（1〜100nm）のものであり、繊維径が2〜3nmの単一繊維からなるシングルセルロースナノファイバー、及び、単一繊維が束ねてできた繊維径20〜100nmのマルチセルロースナノファイバーを含む。
本発明におけるCNFは、どのような製造方法で製造されたものでもよいが、例えば、水に漬けられ、水が浸み込んだ木粉をディスクミルでナノサイズの繊維径まで繊維化することにより製造することができる。
In the present invention, CNF has a fiber diameter of nano size (1 to 100 nm), and is a single cellulose nanofiber composed of a single fiber having a fiber diameter of 2 to 3 nm, and a fiber formed by bundling a single fiber. Contains multicellulose nanofibers with a diameter of 20-100 nm.
The CNF in the present invention may be produced by any production method. For example, wood flour soaked in water and soaked in water is fiberized to a nano-sized fiber diameter with a disc mill. Can be manufactured.
本発明における炭素粒子・チタニアコアシェル複合体は、炭素粒子の表面にチタニアが被覆されたものである。その可視光活性は、限定するものではないが、例えば、次のようにして測定することができる。該炭素粒子・チタニアコアシェル複合体20mgを濃度1mg/mLのメチルオレンジ超純水溶液100mL中に分散した温度298±2Kに保持された分散液に、該分散液の表面から13cm離れ、該表面の照度が0.15W/cm2となるように配置された疑似太陽光源（Xeランプ、300W）からの疑似太陽光を400nm以下の波長をカットするフィルターを介して照射してメチルオレンジを光分解し、その際の速度定数を測定する。 The carbon particle-titania core-shell complex in the present invention is obtained by coating the surface of carbon particles with titania. The visible light activity can be measured, for example, without limitation, as follows. A dispersion in which 20 mg of the carbon particle-titania core-shell complex was dispersed in 100 mL of a methyl orange ultrapure aqueous solution having a concentration of 1 mg / mL was kept at a temperature of 298 ± 2 K, 13 cm away from the surface of the dispersion, and the illuminance of the surface. Methyl orange is photodecomposed by irradiating pseudo-sunlight from a pseudo-solar light source (Xe lamp, 300 W) arranged so that the ratio is 0.15 W / cm 2 through a filter that cuts wavelengths of 400 nm or less. Measure the speed constant at the time.
本発明で用いる炭素粒子・チタニアコアシェル複合体は、有機チタン化合物と炭素粒子を含む混合物を140〜250℃の温度で水熱処理することにより製造することができる。 The carbon particle-titania core-shell composite used in the present invention can be produced by hydrothermally treating a mixture containing an organic titanium compound and carbon particles at a temperature of 140 to 250 ° C.
有機チタン化合物としては、限定するものではないが、チタンテトラブトキシド、チタンテトライソプロポキシド、チタンテトラノルマルブトキシド等のチタンアルコキシド；チタンイソステアレート、トリノルマルブトキシチタンモノステアレート、ジイソプロポキシチタンジステアレート等のチタンアシレート；チタンアセチルアセトネート、チタンテトラアセチルアセトネート、チタンエチルアセトアセテート、チタンオクチレングリコレート等のチタンキレートから選択することができる。好適な有機チタン化合物は、チタンテトラブトキシド、チタンテトライソプロポキシド等である。 Organic titanium compounds include, but are not limited to, titanium alkoxides such as titanium tetrabutoxide, titanium tetraisopropoxide, and titanium tetranormal butoxide; titanium isostearate, trinormal butoxytitanium monostearate, and diisopropoxytitanium di. Titanium acylate such as stearate; can be selected from titanium chelates such as titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetate acetate, and titanium octylene glycolate. Suitable organic titanium compounds are titanium tetrabutoxide, titanium tetraisopropoxide and the like.
有機チタン化合物の溶媒としては、限定するものではないが、例えば、メタノール、エタノール等のアルコール類；エチレングリコールジメチルエーテル等のエーテル類；アセトン等のケトン類；アセトニトリル等のニトリル類；酢酸等のカルボン酸などの有機溶媒を用いることができる。好適な有機溶媒は、エタノール、メタノール、アセトン等である。 The solvent of the organic titanium compound is not limited, for example, alcohols such as methanol and ethanol; ethers such as ethylene glycol dimethyl ether; ketones such as acetone; nitriles such as acetonitrile; carboxylic acids such as acetic acid. And other organic solvents can be used. Suitable organic solvents are ethanol, methanol, acetone and the like.
炭素粒子としては、炭素球等の公知の中実炭素粒子が挙げられる。公知の中実炭素粒子の製造方法は、限定するものではないが、公知のものから適宜選択することができる。例えば、糖類や糖類誘導体を140〜250℃で水熱処理することなどの製造方法を挙げることができる。糖類としては、ブドウ糖、果糖などの単糖類、スクロース等の二糖類が挙げられる。糖類誘導体としては、ソルビトール、スクラロース等の人工甘味料が挙げられる。好適にはスクロース、ブドウ糖を用いることができる。 Examples of carbon particles include known solid carbon particles such as carbon spheres. The known method for producing solid carbon particles is not limited, but can be appropriately selected from known methods. For example, a production method such as hydrothermally treating a saccharide or a saccharide derivative at 140 to 250 ° C. can be mentioned. Examples of saccharides include monosaccharides such as glucose and fructose, and disaccharides such as sucrose. Examples of sugar derivatives include artificial sweeteners such as sorbitol and sucralose. Sucrose and glucose can be preferably used.
また、炭素粒子として、アクリル酸等の不飽和脂肪酸で修飾した修飾炭素粒子を用いると、炭素粒子・チタニアコアシェル複合体や光触媒複合フィルター材の可視光活性をさらに向上することができる。
そのような修飾炭素粒子は、糖類及び／又は糖類誘導体を140〜250℃で水熱処理して炭素粒子を調製する際に、炭素数が3〜20（好ましくは3〜10、より好ましくは3〜6）の不飽和脂肪酸を糖類及び／又は糖類誘導体の溶液中に含有させて水熱処理することにより製造することができる。
前記不飽和脂肪酸としては、限定するものではないが、アクリル酸、クロトン酸、オレイン酸、ソルビン酸、メタクリル酸などの一価不飽和脂肪酸やソルビン酸等の多価不飽和脂肪酸を挙げることができる。
糖類や糖類誘導体の合計量に対する不飽和脂肪酸の使用量は、通常、20〜180wt％、好ましくは30〜150wt％である。
Further, when modified carbon particles modified with unsaturated fatty acids such as acrylic acid are used as the carbon particles, the visible light activity of the carbon particle / titania core-shell composite and the photocatalyst composite filter material can be further improved.
Such modified carbon particles have a carbon number of 3 to 20 (preferably 3 to 10, more preferably 3 to 3) when the saccharide and / or saccharide derivative is hydroheat treated at 140 to 250 ° C. to prepare carbon particles. It can be produced by containing the unsaturated fatty acid of 6) in a solution of a saccharide and / or a saccharide derivative and hydrothermally treating it.
Examples of the unsaturated fatty acid include, but are not limited to, monounsaturated fatty acids such as acrylic acid, crotonic acid, oleic acid, sorbic acid and methacrylic acid, and polyunsaturated fatty acids such as sorbic acid. ..
The amount of unsaturated fatty acids used with respect to the total amount of saccharides and saccharide derivatives is usually 20 to 180 wt%, preferably 30 to 150 wt%.
炭素粒子は、限定するものではないが、その平均粒径（顕微鏡観察による各粒子の粒径〔＝（長径＋短径）／２〕を平均したもの）が1nm〜5μm（好ましくは100nm〜5μm）のものを採用することができる。なお、本発明において炭素球は、顕微鏡観察による炭素粒子の長径と短径とが次の関係を有するものを意味する。
（長径−短径）／（長径＋短径）≦ 0.1
The average particle size of the carbon particles (the average particle size of each particle [= (major axis + minor axis) / 2] as observed under a microscope) is 1 nm to 5 μm (preferably 100 nm to 5 μm). ) Can be adopted. In the present invention, the carbon sphere means that the major axis and the minor axis of the carbon particles as observed by a microscope have the following relationship.
(Major diameter-minor diameter) / (major diameter + minor diameter) ≤ 0.1
炭素粒子は、水に分散した状態で有機チタン化合物溶液と混合することが望ましい。混合物中における有機チタン化合物のチタンと炭素粒子の炭素との重量比は、限定するものではないが、12:1〜50:1 (好ましくは15:1〜40:1)程度とすることができる。前記混合物中における有機溶媒と水の体積比が8:1〜50:１、好ましくは10:1〜30:1である。
水熱温度は、140〜250℃、好ましくは150〜220℃、より好ましくは160〜180℃である。有機溶媒と水の体積比と水熱温度の限定とを組み合わせることにより、後述の速度定数をより高い値とすることができる。
It is desirable that the carbon particles are mixed with the organic titanium compound solution in a state of being dispersed in water. The weight ratio of the titanium of the organic titanium compound to the carbon of the carbon particles in the mixture is not limited, but can be about 12: 1 to 50: 1 (preferably 15: 1 to 40: 1). .. The volume ratio of organic solvent to water in the mixture is 8: 1 to 50: 1, preferably 10: 1 to 30: 1.
The water heat temperature is 140 to 250 ° C, preferably 150 to 220 ° C, and more preferably 160 to 180 ° C. By combining the volume ratio of the organic solvent and water and the limitation of the water heat temperature, the rate constant described later can be set to a higher value.
可視光活性炭素粒子・チタニアコアシェル複合体における炭素粒子表面のチタニアシェルの平均膜厚〔元素マッピング画像において無作為に選択した各炭素粒子上のチタニア膜厚（＝炭素粒子周囲上のチタニアの面積／炭素粒子の周囲長）を複数個について平均したもの〕は、炭素粒子とチタニアとの界面に光が到達する範囲内であればどのような値でも良いが、通常は、１nm以上、実用的には10nm以上である。チタニアの平均膜厚の上限は、必ずしも明確ではないが、100〜300nm程度と考えられる。 Average thickness of titania shell on the surface of carbon particles in visible light activated carbon particle-titania core shell composite [Titania film thickness on each carbon particle randomly selected in element mapping image (= area of titania on carbon particle circumference / The average of the peripheral lengths of multiple carbon particles)] can be any value as long as the light reaches the interface between the carbon particles and titania, but it is usually 1 nm or more, which is practical. Is above 10 nm. The upper limit of the average film thickness of titania is not always clear, but it is considered to be about 100 to 300 nm.
本発明の光触媒複合フィルター材は、その製法はどのようなものでもよいが、例えば、光触媒粉を分散した液中にCNF懸濁液を添加し、超音波処理やその他の撹拌処理などにより十分に混合した後、混合液を適宜のろ過膜でろ過し、ろ過膜上の堆積物を乾燥することにより製造することができる。分散液や懸濁液の液体としては、限定するものではないが、好適には水を用いる。 The photocatalyst composite filter material of the present invention may be produced by any method. For example, a CNF suspension is added to a liquid in which photocatalyst powder is dispersed, and the photocatalyst composite filter material is sufficiently subjected to ultrasonic treatment or other stirring treatment. After mixing, the mixed solution can be produced by filtering with an appropriate filtration membrane and drying the deposit on the filtration membrane. The dispersion liquid or suspension liquid is not limited, but water is preferably used.
光触媒複合フィルター材における光触媒とCNFとの重量割合は、フィルター材の用途や光照射の態様などにも依存するが、通常は、1:10〜10:1程度(好ましくは1:5〜5:1、より好ましくは1:2〜2:1)とすることができる。 The weight ratio of the photocatalyst to the CNF in the photocatalyst composite filter material depends on the application of the filter material and the mode of light irradiation, but is usually about 1: 10 to 10: 1 (preferably 1: 5 to 5 :). It can be 1, more preferably 1: 2 to 2: 1).
以下、本発明を実施例によりさらに具体的に説明するが、本発明はこれらの実施例等によって何ら限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples and the like.
＜炭素球・チタニアコアシェル複合体の合成＞
本発明のフィルター材に複合する光触媒としての炭素球・チタニアコア-シェル複合体（TiO2@CS）は、以下の記載のように、2段階の水熱工程を通じて合成した。
濃度0.2モル/L のスクロース溶液16mLをテフロン（登録商標）容器（容量：25mL）に入れ、該容器をステンレス鋼製オートクレーブに封入し、448Kで4時間水熱処理を行った。室温に冷却後、炭素球（CS）の固体沈殿物が出現した容器を取り出し、固体沈殿物を遠心分離により収集し、脱イオン（DI）水で2回洗浄した後、CSをDI水中に分散して、CS濃度5mg/mLの分散液を得た。
0.1mLのチタン（IV）テトラブトキシド〔(Ti(OBu)4〕 〔和光純薬工業（株）製、試薬特級〕を攪拌しながら12mLのエタノール〔和光純薬工業（株）製、純度99％〕中に溶解した。該溶解液中に0.6mLのCS分散液を加え、2分間撹拌した後、その混合物をテフロン（登録商標）容器（容量：25mL）に入れた。該容器をステンレス鋼製オートクレーブに封入し、433Kで3時間水熱処理を行った。室温に冷却後、粉末沈殿物が出現した容器を取り出し、粉末沈殿物を遠心分離により収集し、DI水とエタノール〔和光純薬工業（株）製、純度99％〕で繰り返し洗浄し、323Kで一晩乾燥して実施例で用いる光触媒としてのTiO2@CSを得た。
<Synthesis of carbon sphere / titania core shell complex>
The carbon sphere-titania core-shell complex (TiO 2 @ CS) as a photocatalyst to be combined with the filter material of the present invention was synthesized through a two-step hydrothermal process as described below.
16 mL of a sucrose solution having a concentration of 0.2 mol / L was placed in a Teflon (registered trademark) container (capacity: 25 mL), the container was sealed in a stainless steel autoclave, and hydrothermal treatment was performed at 448 K for 4 hours. After cooling to room temperature, the container in which the solid precipitate of carbon spheres (CS) appeared was taken out, the solid precipitate was collected by centrifugation, washed twice with deionized (DI) water, and then CS was dispersed in DI water. Then, a dispersion having a CS concentration of 5 mg / mL was obtained.
While stirring 0.1 mL of titanium (IV) tetrabutoxide [(Ti (OBu) 4 ] [manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent], 12 mL of ethanol [manufactured by Wako Pure Chemical Industries, Ltd., purity 99%] ]. 0.6 mL of CS dispersion was added to the solution, and after stirring for 2 minutes, the mixture was placed in a Teflon (registered trademark) container (volume: 25 mL). The container was made of stainless steel. It was sealed in an autoclave and hydrothermally treated at 433 K for 3 hours. After cooling to room temperature, the container in which the powder precipitate appeared was taken out, and the powder precipitate was collected by centrifugation, and DI water and ethanol [Wako Pure Chemical Industries (Wako Pure Chemical Industries, Ltd.) Co., Ltd., purity 99%] was repeatedly washed, and the mixture was dried overnight at 323 K to obtain TiO 2 @ CS as a photocatalyst used in Examples.
＜セルロースナノファイバーの調製）
一晩水に漬けられ、水が浸み込んだ木粉を、ディスクミル(増幸産業(株)製 MKCA6-2)により、間隙150μm、1800rpmの回転速度の条件で繰り返し繊維化してセルロースナノファイバ（CNF）を含む懸濁液を得た。懸濁液から採取したCNFをSEMで観察した結果、その繊維径は、15〜50nmの範囲の径分布を有するものであった(平均繊維径約15〜20nm程度)。
<Preparation of cellulose nanofibers)
Wood flour that has been soaked in water overnight and soaked in water is repeatedly fiberized by a disc mill (MKCA6-2 manufactured by Masuko Sangyo Co., Ltd.) under the conditions of a gap of 150 μm and a rotation speed of 1800 rpm to make cellulose nanofibers (cellulose nanofibers). A suspension containing CNF) was obtained. As a result of observing the CNF collected from the suspension with SEM, the fiber diameter had a diameter distribution in the range of 15 to 50 nm (average fiber diameter of about 15 to 20 nm).
＜各光触媒の紫外光・可視光拡散反射スペクトル＞
上記光触媒TiO2@CSの合成において製造された実施例の光触媒以外に、比較例の触媒として市販の酸化チタンP25（Evonik Degussa社）、Pt/TiO2（石原産業（株）MPT-623）を用いた。
それら光触媒粉末について、紫外光-可視光拡散反射スペクトル（UV-vis DRS）を、積分球を付属させた紫外光-可視光分光光度計（日本分光(株) V-650）で記録した。測定用のリファレンス材料として硫酸カルシウム（BaSO4）を使用した。その結果を図１中の（ａ）〜（ｃ）として示す〔縦軸のＫ/Ｍは、クベルカ−モンク（Kubelka-Munk）関数〕。比較例の光触媒(a)P25、(b)Pt/TiO2では吸収端が410nm近くなっているのに対し、実施例の光触媒(c) TiO2@CSでは700nm付近から光吸収が起こっており、可視光吸収性能が高くなっていることを示している。このことは、実施例の光触媒（ｃ）は、410nm以上での可視光活性が比較例の光触媒（ａ）、（ｂ）に比べ大きいことを裏付けているといえる。
<Ultraviolet light / visible light diffuse reflection spectrum of each photocatalyst>
In addition to the photocatalysts of Examples produced in the synthesis of the above photocatalyst TiO 2 @ CS, commercially available titanium oxide P25 (Evonik Degussa) and Pt / TiO 2 (Ishihara Sangyo Co., Ltd. MPT-623) were used as comparative catalysts. Using.
For these photocatalytic powders, the ultraviolet-visible light diffuse reflection spectrum (UV-vis DRS) was recorded with an ultraviolet-visible light spectrophotometer (Nippon Kogaku Co., Ltd. V-650) equipped with an integrating sphere. Calcium sulfate (BaSO 4 ) was used as a reference material for measurement. The results are shown as (a) to (c) in FIG. 1 [K / M on the vertical axis is the Kubelka-Munk function]. In the photocatalysts (a) P25 and (b) Pt / TiO 2 of the comparative example, the absorption end is close to 410 nm, whereas in the photocatalyst (c) TiO 2 @ CS of the example, light absorption occurs from around 700 nm. , Indicates that the visible light absorption performance is high. This can be said to support that the photocatalyst (c) of the example has a higher visible light activity at 410 nm or more than the photocatalysts (a) and (b) of the comparative example.
＜CNFフィルター材の製造とその紫外光-可視光透過率＞
10mLのDI水に上記で得られたCNFを含む懸濁液2gを添加し、2分間の超音波処理後、連続的に1時間撹拌した。撹拌後の懸濁液を表面が清浄な石英基板上に滴下してCNF膜を形成した。石英基板上のCNF膜を空気中323Kで一晩乾燥し、目付量約0.6mg/cm2のCNFフィルター材を得た。
得られたフィルター材について、紫外光-可視光拡散反射スペクトル（DRS）を、積分球を付属させた紫外光-可視光分光光度計（日本分光(株) V-650）で記録した。測定用のリファレンス材料としてフィルター材を載せなかった石英基板を使用した。その結果の透過スペクトルを図１中の（ｄ）として示す〔縦軸のT（％）は透過率〕。CNFフィルター材は、紫外領域のように波長が短いほど透過率が低く、可視光領域のように波長が長いほど透過率が高くなっている。このことは、紫外線がCNFフィルター材の内部まで透過しにくいのに対し、可視光は紫外光よりもCNFフィルター材の内部まで透過しやすいことを意味しており、可視光活性光触媒を分散して含有するフィルター材の素材としてCNFが望ましいものであることを証明するものといえる。
<Manufacturing of CNF filter material and its ultraviolet light-visible light transmittance>
To 10 mL of DI water, 2 g of the suspension containing the CNF obtained above was added, and after sonication for 2 minutes, the mixture was continuously stirred for 1 hour. The stirred suspension was dropped onto a quartz substrate having a clean surface to form a CNF film. The CNF film on the quartz substrate was dried in air at 323 K overnight to obtain a CNF filter material having a basis weight of about 0.6 mg / cm 2.
For the obtained filter material, the ultraviolet light-visible light diffuse reflection spectrum (DRS) was recorded with an ultraviolet light-visible light spectrophotometer (JASCO Corporation V-650) equipped with an integrating sphere. A quartz substrate without a filter material was used as a reference material for measurement. The resulting transmission spectrum is shown as (d) in FIG. 1 [T (%) on the vertical axis is the transmittance]. The shorter the wavelength of the CNF filter material, the lower the transmittance, and the longer the wavelength, the higher the transmittance, such as the visible light region. This means that while ultraviolet rays are difficult to penetrate into the CNF filter material, visible light is more likely to penetrate into the CNF filter material than ultraviolet light, and the visible light active photocatalyst is dispersed. It can be said that it proves that CNF is desirable as a material for the filter material contained.
＜光触媒複合フィルター材の製造＞
10mgの各光触媒粉（P25,Pt-TiO2、又は、TiO2@CS）を10mLのDI水中に分散した。該分散液に濃度0.567wt％のCNF懸濁液2gを添加し、得られた混合液を2分間の超音波処理後、連続的に1時間撹拌した。撹拌後の混合液を市販のろ紙〔No.5C、(株)アドバンテック製〕でろ過し、ろ紙上に光触媒粉を含むCNFフィルター材を形成した。フィルター材は、空気中323Kで一晩乾燥した。
<Manufacturing of photocatalytic composite filter material>
10 mg of each photocatalytic powder (P25, Pt-TiO 2 , or TiO 2 @ CS) was dispersed in 10 mL of DI water. 2 g of a CNF suspension having a concentration of 0.567 wt% was added to the dispersion, and the obtained mixture was sonicated for 2 minutes and then continuously stirred for 1 hour. The mixed solution after stirring was filtered through a commercially available filter paper [No. 5C, manufactured by Advantech Co., Ltd.] to form a CNF filter material containing a photocatalytic powder on the filter paper. The filter material was dried overnight at 323 K in air.
＜光触媒及び光触媒複合フィルター材の光触媒性能＞
光触媒複合フィルター材の性能試験は、有機汚染物質を分解することにより調べた。標的の有機汚染物質としてメチルオレンジ（MO）を採用した。出発溶液の初期濃度（C0）を5mg・mL-1とし、20mgの光触媒をガラス容器中の100mLのMOに加え、2分間の超音波処理により分散させた。ガラス容器を石英カバーでフタをし、疑似太陽光光源（Jasco BS-300 type Xe lamp, 300W）の13cm下が液面となり、該液の頂部の照度が0.15W/cm2となるように載置した。反応中、反応器の温度は、水浴中で297±2Kに制御された。照射前に、懸濁液は、吸着平衡が達成されるように、暗中で1時間磁気的に撹拌した。400nm以下の波長をカットするフィルターを使用するか否かにより、可視光の照射、又は、フルスペクトル（全スペクトル）の太陽光の照射を行った。異なった時間間隔で、約1mLの上済み液を遠心分離により採取し、有機汚染物としてのMOの濃度を高速液体クロマトグラフィー（HPLC）システム（島津製作所製 プロミネンス）により解析した。なお、前記HPLCシステムは、2つの送液ポンプ（LC-20AD）、脱ガス装置（DGU-20A3）、オートサンプラ（SIL-20AC）、カラムオーブン（CTO-20AC）、及び、ダイオードアレイ検出器（SPD-M20A）から構成されている。
その結果を図２（ａ）、（ｂ）に示す。（ａ）は、各光触媒単独の光分解速度定数を、（ｂ）は、各光触媒を含むCNFフィルター材の光分解速度定数を、各図面の上段■は太陽光の全スペクトル照射の場合を、中段◆は400nm以下の波長をカットした太陽光照射の場合を、下段●はLEDライト照射の場合をそれぞれ示す。本発明の実施例の光触媒TiO2@CSは、紫外光を含む太陽光照射下での光分解速度定数が比較例の光触媒P25、Pt/TiO2より低いものの、CNFフィルター材に含有させた場合には、紫外光を含む太陽光、400nm以下の波長をカットした太陽光、LEDライトのいずれの照射下においても、比較例の光触媒P25、Pt/TiO2よりも高い光分解速度定数を示した。
<Photocatalyst performance of photocatalyst and photocatalyst composite filter material>
The performance test of the photocatalytic composite filter material was examined by decomposing organic pollutants. Methyl orange (MO) was used as the target organic pollutant. The initial concentration (C0) of the starting solution was 5 mg · mL -1 , 20 mg of photocatalyst was added to 100 mL of MO in a glass container, and the mixture was dispersed by sonication for 2 minutes. Cover the glass container with a quartz cover, and place it so that the liquid level is 13 cm below the pseudo-solar light source (Jasco BS-300 type Xe lamp, 300 W) and the illuminance at the top of the liquid is 0.15 W / cm 2. I put it. During the reaction, the reactor temperature was controlled to 297 ± 2K in a water bath. Prior to irradiation, the suspension was magnetically stirred in the dark for 1 hour to achieve adsorption equilibrium. Depending on whether or not a filter that cuts wavelengths of 400 nm or less is used, visible light irradiation or full spectrum (whole spectrum) sunlight irradiation was performed. Approximately 1 mL of the finished liquid was collected by centrifugation at different time intervals, and the concentration of MO as an organic contaminant was analyzed by a high performance liquid chromatography (HPLC) system (Prominence manufactured by Shimadzu Corporation). The HPLC system includes two liquid feed pumps (LC-20AD), a degassing device (DGU-20A3), an auto sampler (SIL-20AC), a column oven (CTO-20AC), and a diode array detector ( It is composed of SPD-M20A).
The results are shown in FIGS. 2 (a) and 2 (b). (A) is the photodecomposition rate constant of each photocatalyst alone, (b) is the photodecomposition rate constant of the CNF filter material containing each photocatalyst, and the upper part of each drawing is the case of full spectrum irradiation of sunlight. The middle ◆ indicates the case of sunlight irradiation with wavelengths of 400 nm or less cut, and the lower ● indicates the case of LED light irradiation. Although the photocatalyst TiO 2 @ CS of the example of the present invention has a lower photocatalyst rate constant under sunlight irradiation including ultraviolet light than the photocatalysts P25 and Pt / TiO 2 of the comparative example, it is contained in the CNF filter material. Showed a higher photodissociation rate constant than the photocatalysts P25 and Pt / TiO 2 of the comparative example under the irradiation of sunlight including ultraviolet light, sunlight with wavelengths of 400 nm or less cut, and LED light. ..
＜光触媒複合フィルター材の耐汚染性と耐久性の試験＞
光触媒複合フィルター材の耐汚染性と耐久性は、下記の（Ａ）工程と（Ｂ）工程とを1サイクルとする3サイクルで、下水処理プラントで得られた活性汚泥を含む実際の下水により評価した。
最初に、真空ポンプ（約-40cmHg）を吸引器として備えたブフナー漏斗システムを用い、新鮮な光触媒複合フィルター材について、脱イオン水の流量を測定した。
（Ａ）工程：
脱イオン水の流量を測定した光触媒複合フィルター材は、それを支持する膜とともに、ガラス容器中の27mLの活性汚泥下水中に浸漬され、ガラス容器に石英板で蓋をし、下水中に連続的に気泡を形成しながら、LED光（オーム電機製、15W）により連続的に6時間又は24時間光照射する。上記の時間経過後、光触媒複合フィルター材を取り外し、バクテリア残留物を洗い流すように新鮮な純水で3回洗浄する。洗浄後のフィルター材について、前記ブフナーろ過システムを用いて、脱イオン水の流量を測定する。
（Ｂ）工程：
上記（Ａ）工程で脱イオン水の流量を測定した光触媒複合フィルター材は、それを支持する膜とともに、ガラス容器中の27mLの純水中に浸漬され、ガラス容器に石英板で蓋をして、LED光により連続的に24時間光照射する。24時間経過後、光触媒複合フィルター材は取り出され、新鮮な純水で3回洗浄する。洗浄後の光触媒複合フィルター材について、前記ブフナーろ過システムを用いて、脱イオン水の流量を測定する。
<Test of stain resistance and durability of photocatalytic composite filter material>
The stain resistance and durability of the photocatalyst composite filter material are evaluated by the actual sewage containing activated sludge obtained in the sewage treatment plant in 3 cycles including the following steps (A) and (B) as one cycle. did.
First, the flow rate of deionized water was measured for a fresh photocatalytic composite filter material using a Büchner funnel system equipped with a vacuum pump (approximately -40 cmHg) as an aspirator.
(A) Step:
The photocatalyst composite filter material whose flow rate of deionized water was measured was immersed in 27 mL of active sludge sewage in a glass container together with a film supporting it, the glass container was covered with a quartz plate, and the glass container was continuously submerged in sewage. While forming bubbles in the glass, the LED light (manufactured by Ohm Electric Co., Ltd., 15W) continuously irradiates the light for 6 hours or 24 hours. After the above time elapses, the photocatalytic composite filter material is removed and washed 3 times with fresh pure water to wash away bacterial residues. For the filtered filter material after cleaning, the flow rate of deionized water is measured using the Büchner filtration system.
(B) Step:
The photocatalytic composite filter material whose flow rate of deionized water was measured in the above step (A) is immersed in 27 mL of pure water in a glass container together with a film supporting the photocatalytic composite filter material, and the glass container is covered with a quartz plate. , The LED light continuously irradiates the light for 24 hours. After 24 hours, the photocatalytic composite filter material is removed and washed 3 times with fresh pure water. For the photocatalytic composite filter material after cleaning, the flow rate of deionized water is measured using the Büchner filtration system.
脱イオン水の流量は、光触媒複合フィルター材の使用前と、各サイクルの（Ａ）工程、（Ｂ）工程のそれぞれの最後の段階で記録された。その結果を図３に示す。下方の◆と◇は、比較例のCNF-Pt/TiO2フィルター材を、上方の●と○は実施例のCNF-TiO2@CSフィルター材をそれぞれ示す。また、◆と●は、１サイクル毎、6時間の下水中浸漬と18時間の純水中浸漬を行ったものを、◇と○は、１サイクル毎に24時間の下水中浸漬と24時間の純水中浸漬を行ったものを、それぞれ示す。本実施例のCNF-TiO2@CSフィルター材は、全てのサイクルの全ての工程において比較例のCNF-Pt/TiO2フィルター材よりも顕著に高い流量を示した。特に、6時間の下水中浸漬と18時間の純水中浸漬を行ったもの（上方の●）については、3サイクルを経過したものでも高い流量を維持することを示した。 The flow rate of the deionized water was recorded before the use of the photocatalytic composite filter material and at the final stage of each of the steps (A) and (B) of each cycle. The result is shown in FIG. The lower ◆ and ◇ indicate the CNF-Pt / TiO 2 filter material of the comparative example, and the upper ● and ○ indicate the CNF-TiO 2 @ CS filter material of the example. In addition, ◆ and ● are those that have been immersed in sewage for 6 hours and 18 hours in pure water for each cycle, and ◇ and ○ are those that have been immersed in sewage for 24 hours and 24 hours for each cycle. The ones immersed in pure water are shown. The CNF-TiO 2 @CS filter material of this example showed a significantly higher flow rate than the CNF-Pt / TiO 2 filter material of the comparative example in all steps of all cycles. In particular, it was shown that high flow rates were maintained even after 3 cycles for those that had been immersed in sewage for 6 hours and immersed in pure water for 18 hours (● above).
図４に、実施例のCNF-TiO2@CSフィルター材(上側)と比較例のCNF-Pt/TiO2フィルター材（下側）についての写真と、Syto9核酸蛍光剤 nucleic acid fluorescent agent.で染色後、レーザー走査型共焦点顕微鏡（カールツァイスマイクロスコピー（株）製 LSM 880）で観察した表面顕微鏡像を示す。フィルター表面のバクテリア汚染された状態は、Syto9核酸蛍光剤 nucleic acid fluorescent agent.で染色後、レーザー走査型共焦点顕微鏡（カールツァイスマイクロスコピー（株）製 LSM 880）で観察した。左から順番に、未使用の光触媒複合フィルター材の写真、LED光照射下で6時間活性汚泥下水中に浸漬した後の光触媒複合フィルター材の写真、LED光照射下で6時間活性汚泥下水中に浸漬した後の光触媒複合フィルター材の微生物を緑に染色した表面顕微鏡像（灰色：フィルター材料、緑：微生物）、該表面顕微鏡像について、背景のフィルター材の像を黒にし、微生物の像だけをハイライト表示した表面顕微鏡像、をそれぞれ示す。
これらの写真や顕微鏡像から明らかなように、本発明の実施例のCNF-TiO2@CSフィルター材では、比較例に比べて微生物量が顕著に少なくなっている。
FIG. 4 shows photographs of the CNF-TiO 2 @ CS filter material (upper side) of the example and the CNF-Pt / TiO 2 filter material (lower side) of the comparative example, and staining with the Syto9 nucleic acid fluorescent agent. Later, a surface microscope image observed with a laser scanning confocal microscope (LSM 880 manufactured by Karl Zeiss Microscopy Co., Ltd.) is shown. The bacterially contaminated state of the filter surface was stained with a Syto9 nucleic acid fluorescent agent. And then observed with a laser scanning confocal microscope (LSM 880 manufactured by Carl Zeiss Microscopy Co., Ltd.). From left to right, a photograph of an unused photocatalyst composite filter material, a photograph of a photocatalyst composite filter material after being immersed in activated sludge sewage for 6 hours under LED light irradiation, and a photograph of a photocatalyst composite filter material after being immersed in activated sludge sewage under LED light irradiation for 6 hours. For the surface microscope image (gray: filter material, green: microorganism) in which the microorganisms of the photocatalyst composite filter material after immersion are dyed green, the image of the background filter material is made black, and only the image of the microorganism is shown. The highlighted surface microscope images are shown respectively.
As is clear from these photographs and microscopic images, the amount of microorganisms in the CNF-TiO 2 @CS filter material of the examples of the present invention is significantly smaller than that of the comparative examples.
＜アクリル酸修飾炭素球の合成＞
5.472ｇのスクロース（和光純薬工業（株）、特級）を60mLの純水中に添加し、2分間の超音波処理とその後の10分間のマグネティックスターラーによる撹拌により溶解し、溶液Aを得た。所定量のアクリル酸（濃度99.0％以上、東京化成工業製）をスクロースに対し重量比xとなるように20mLの純水と混合し、溶液Bを形成した。その後、溶液Bは撹拌中の溶液A中に滴々で添加した。連続的に10分間撹拌後、混合物はテフロン（登録商標）でライニングされた容器中に移し、ステンレス鋼オートクレーブ中に密封した。463K16時間の水熱処理後、該オートクレーブを自然冷却した。遠心分離と、純水による2回の洗浄、353Kでの一晩中の乾燥によりアクリル酸修飾炭素球（以下、「CS-xAA」ということがある。）のサンプルを得た。
<Synthesis of acrylic acid-modified carbon spheres>
5.472 g of sucrose (Wako Pure Chemical Industries, Ltd., special grade) was added to 60 mL of pure water and dissolved by sonication for 2 minutes followed by stirring with a magnetic stirrer for 10 minutes to obtain Solution A. .. A predetermined amount of acrylic acid (concentration: 99.0% or more, manufactured by Tokyo Chemical Industry Co., Ltd.) was mixed with 20 mL of pure water so as to have a weight ratio x with respect to sucrose to form a solution B. Solution B was then added in drops into Solution A under stirring. After continuous stirring for 10 minutes, the mixture was transferred into a Teflon® lined container and sealed in a stainless steel autoclave. After hydrothermal treatment at 463K for 16 hours, the autoclave was naturally cooled. A sample of acrylic acid-modified carbon spheres (hereinafter sometimes referred to as "CS-xAA") was obtained by centrifugation, washing twice with pure water, and drying at 353 K overnight.
＜アクリル酸修飾炭素球・チタニアコアシェル複合体の合成＞
0.8mLのチタン(IV)テトラブトキシド〔Ti(OBu)4〕を60mLのエタノール中に溶解し、2分間連続的に撹拌することにより、淡黄色のチタン(IV)テトラブトキシド〔Ti(OBu)4〕の溶液を得た。該溶液に1.2ｇのCS-xAAを加え、2分間超音波処理してCS-xAAの分散溶液を形成した。その後、該分散溶液に2.4mLの純水を加えて、白色の沈殿物が徐々に現れた。さらに2分間連続的に撹拌した後、該撹拌混合物をテフロン（登録商標）でライニングされた容器に移し、ステンレス鋼オートクレーブ中に密封した。463K3時間の水熱処理後、該オートクレーブを自然冷却した。遠心分離と、純水による洗浄とエタノールによる洗浄を繰り返し、353Kでの一晩中の乾燥によりアクリル酸修飾炭素球・チタニアコアシェル複合体（以下、「TiO2@CS-xAA」ということがある。）のサンプルを得た。
<Synthesis of acrylic acid-modified carbon sphere-titania core-shell complex>
By dissolving 0.8 mL of titanium (IV) tetrabutoxide [Ti (OBu) 4 ] in 60 mL of ethanol and stirring continuously for 2 minutes, pale yellow titanium (IV) tetrabutoxide [Ti (OBu) 4] ] Solution was obtained. 1.2 g of CS-xAA was added to the solution and sonicated for 2 minutes to form a dispersed solution of CS-xAA. Then, 2.4 mL of pure water was added to the dispersion solution, and a white precipitate gradually appeared. After continuous stirring for an additional 2 minutes, the stirring mixture was transferred to a Teflon® lined container and sealed in a stainless steel autoclave. After hydrothermal treatment for 463K for 3 hours, the autoclave was naturally cooled. Centrifugation, washing with pure water, and washing with ethanol are repeated, and drying at 353 K overnight may be referred to as an acrylic acid-modified carbon sphere-titania core-shell complex (hereinafter, "TiO 2 @ CS-xAA"). ) Was obtained.
＜表面官能基のモル比、ゼータ電位の測定＞
上記で得られたCS-xAAサンプルについては、X線光電子分光計（XPS、アルバック・ファイ（株）製ULVAC-PHI 5000 Versa Probeタイプ）を用い、表面の各種官能基のモル比を、C-C/C=C（285.3ev、50%L:50%G）、C-OH/C-O-C（286.3ev、100%G）、C=O（287.4ev、100%G）として、また、〜COO/COOH（289.6ev、100%G）はC 1sのピーク分離、＝O/-O-（532.7ev、100%G）、-O（533.9ev、100%G）はO 1sのピーク分離から、それぞれ求めた（ただし、L：Lorentz関数、G：Gaussian関数）。その結果を図５（ａ）に示す。
また、CS-xAAサンプルを0.5mg/mLとなるように純水に混合し、各サンプルのゼータ電位をゼータ電位・粒径測定システム（大塚電子（株）製ELSZ-1000タイプ）で測定した。その結果を図５（ｂ）に示す。
これらの図面から、アクリル酸が50wt％の前後において、各種官能基のうち酸性-OH（C-OH/C-O-C）のモル比が高く、ゼータ電位の絶対値が高くなっていることが分かる。一方、アクリル酸が200wt％程度であるときも酸性-OHのモル比が高く、ゼータ電位の絶対値が高くなっているが、同時に、C=Oや＝O/-O-、-Oのモル比も高くなっており、表面の酸化程度が進行しすぎて炭素の骨格構造が変化していることもうかがえる。
<Measurement of molar ratio of surface functional groups and zeta potential>
For the CS-xAA sample obtained above, an X-ray photoelectron spectrometer (XPS, ULVAC-PHI 5000 Versa Probe type manufactured by ULVAC-PHI, Inc.) was used to determine the molar ratio of various functional groups on the surface to CC /. As C = C (285.3ev, 50% L: 50% G), C-OH / COC (286.3ev, 100% G), C = O (287.4ev, 100% G), and ~ COO / COOH ( 289.6ev, 100% G) was obtained from the peak separation of C 1s, and = O / -O- (532.7ev, 100% G) and -O (533.9ev, 100% G) were obtained from the peak separation of O 1s. (However, L: Lorentz function, G: Gaussian function). The result is shown in FIG. 5 (a).
In addition, CS-xAA samples were mixed with pure water to a concentration of 0.5 mg / mL, and the zeta potential of each sample was measured with a zeta potential / particle size measurement system (ELSZ-1000 type manufactured by Otsuka Electronics Co., Ltd.). The result is shown in FIG. 5 (b).
From these drawings, it can be seen that the molar ratio of acidic-OH (C-OH / COC) among various functional groups is high and the absolute value of the zeta potential is high when acrylic acid is around 50 wt%. On the other hand, when acrylic acid is about 200 wt%, the molar ratio of acidic-OH is high and the absolute value of zeta potential is high, but at the same time, the molar ratio of C = O and = O / -O-, -O is high. The ratio is also high, and it can be seen that the degree of surface oxidation has progressed too much and the skeletal structure of carbon has changed.
＜TiO2@CS-xAAサンプルの光触媒性能試験＞
TiO2@CS-xAAサンプルの光触媒性能試験は、標的の有機汚染物質としてメチルオレンジ（MO）を採用し、以下の手順でMOを分解することにより調べた。
出発溶液の初期濃度（C0）を5mg・mL-1とし、20mgの光触媒をガラス容器中の100mLのMOに加え、2分間の超音波処理により分散させた。ガラス容器を石英カバーでフタをし、疑似太陽光光源（Jasco BS-300 type Xe lamp, 300W）の13cm下が液面となり、該液の頂部の照度が0.15W/cm2となるように載置した。反応中、反応器の温度は、水浴中で298±2Kに制御された。照射前に、懸濁液は、吸着平衡が達成されるように、暗中で1時間マグネティックスターラーで撹拌した。400nmのカットオフフィルターを使用するか否かにより、可視光の照射、又は、フルスペクトル（全スペクトル）の太陽光の照射を行った。異なった時間間隔で、約1mLの上済み液を遠心分離により採取し、有機汚染物としてのMOの濃度を高速液体クロマトグラフィー（HPLC）システム（（株）島津製作所製プロミネンス）により解析した。なお、前記HPLCシステムは、2つの送液ポンプ（LC-20AD）、脱ガス装置（DGU-20A3）、オートサンプラ（SIL-20AC）、カラムオーブン（CTO-20AC）、及び、ダイオードアレイ検出器（SPD-M20A）から構成されている。
試験結果を図６に示す。アクリル酸が約50wt％のとき光分解速度定数ｋが最も高く、アクリル酸が150wt％を超えると光分解速度定数ｋは徐々に低下した。この試験結果と図５（ａ）の各種官能基のモル比、図５（ｂ）のゼータ電位の結果とを併せ考慮すると、炭素の骨格構造が大きく変化しない程度に酸性-OH官能基を増加させることで光触媒性能を向上させることができるといえる。なお、上記実施例ではアクリル酸を用いたが、他の不飽和脂肪酸を用いても、同様の官能基やゼータ電位調整作用を有すると考えられるので、同様の光触媒性能の向上効果が得られることが想定される。
なお、TiO2@CS-xAAサンプルについては、複合フィルター材とした例は示していないが、TiO2@CSと同様のコアシェル構造でありながら、その可視光活性がTiO2@CSよりも高いことから、複合フィルター材とした際には、TiO2@CSを用いた場合以上の可視光活性を有することが容易に予想される。
< Photocatalytic performance test of TiO 2 @ CS-xAA sample>
The photocatalytic performance test of the TiO 2 @ CS-xAA sample was carried out by using methyl orange (MO) as the target organic pollutant and decomposing MO by the following procedure.
The initial concentration (C0) of the starting solution was 5 mg · mL -1 , 20 mg of photocatalyst was added to 100 mL of MO in a glass container, and the mixture was dispersed by sonication for 2 minutes. Cover the glass container with a quartz cover, and place it so that the liquid level is 13 cm below the pseudo-solar light source (Jasco BS-300 type Xe lamp, 300 W) and the illuminance at the top of the liquid is 0.15 W / cm 2. I put it. During the reaction, the reactor temperature was controlled to 298 ± 2K in a water bath. Prior to irradiation, the suspension was stirred in the dark with a magnetic stirrer for 1 hour to achieve adsorption equilibrium. Depending on whether or not a 400 nm cutoff filter was used, visible light irradiation or full spectrum (whole spectrum) sunlight irradiation was performed. Approximately 1 mL of the finished liquid was collected by centrifugation at different time intervals, and the concentration of MO as an organic contaminant was analyzed by a high performance liquid chromatography (HPLC) system (Prominence manufactured by Shimadzu Corporation). The HPLC system includes two liquid feed pumps (LC-20AD), a degassing device (DGU-20A3), an auto sampler (SIL-20AC), a column oven (CTO-20AC), and a diode array detector ( It is composed of SPD-M20A).
The test results are shown in FIG. When acrylic acid was about 50 wt%, the photolysis rate constant k was the highest, and when acrylic acid exceeded 150 wt%, the photolysis rate constant k gradually decreased. Considering this test result, the molar ratio of various functional groups in FIG. 5 (a), and the zeta potential result in FIG. 5 (b), the acidic-OH functional groups are increased to the extent that the skeleton structure of carbon does not change significantly. It can be said that the photocatalyst performance can be improved by making the mixture. Although acrylic acid was used in the above examples, it is considered that other unsaturated fatty acids also have the same functional group and zeta potential adjusting action, so that the same effect of improving photocatalytic performance can be obtained. Is assumed.
Note that the TiO 2 @ CS-xAA sample does not show the example composite filter material, yet similar core-shell structure and TiO 2 @CS, the visible light activity is higher than the TiO 2 @CS Therefore, when it is used as a composite filter material, it is easily expected that it has more visible light activity than when TiO 2 @ CS is used.
本発明の光触媒複合フィルター材は、可視光領域での活性が比較的高く、バクテリア等の汚染や汚染等による流量低下が比較的少ないので、汚染物分解フィルター材、抗菌性フィルター材、光触媒膜反応器、アンチファウリング膜材料などとして有用に使用することが期待される。
The photocatalytic composite filter material of the present invention has relatively high activity in the visible light region, and the flow rate decrease due to contamination by bacteria or the like is relatively small. Therefore, a pollutant decomposition filter material, an antibacterial filter material, and a photocatalytic membrane reaction It is expected to be usefully used as a vessel, anti-fowling membrane material, etc.
Claims (10)
The method for producing a photocatalytic composite filter material according to claim 9, wherein the unsaturated fatty acid is 20 to 180 wt% of the total amount of the saccharide and the saccharide derivative.
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