JPH0117435B2 - - Google Patents
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- Publication number
- JPH0117435B2 JPH0117435B2 JP14010684A JP14010684A JPH0117435B2 JP H0117435 B2 JPH0117435 B2 JP H0117435B2 JP 14010684 A JP14010684 A JP 14010684A JP 14010684 A JP14010684 A JP 14010684A JP H0117435 B2 JPH0117435 B2 JP H0117435B2
- Authority
- JP
- Japan
- Prior art keywords
- semiconductor
- metal ions
- light
- heavy metal
- catalyst
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Treatment Of Water By Oxidation Or Reduction (AREA)
- Catalysts (AREA)
- Physical Water Treatments (AREA)
- Removal Of Specific Substances (AREA)
Description
【発明の詳細な説明】
本発明は半導体粉末の光照射時の酸化力で、廃
水中の重金属イオンを酸化して酸化物として沈漬
させることによつて廃水から除去する方法に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing heavy metal ions from wastewater by oxidizing them using the oxidizing power of semiconductor powder when irradiated with light and allowing the ions to immerse as oxides.
二酸化チタンの電極を用いて光照射により水を
分解して、水素と酸素を発生させる画期的な研究
が発表されて以来、半導体を用いる光エネルギー
利用の試みが行なわれている。半導体触媒の特徴
はその強い酸化及び還元の力にあり、水に対して
は還元により水素を発生し、酸化により酸素を発
生する。本発明は、このような半導体の光照射時
の酸化力を利用して、廃水中の重金属イオンを酸
化物に交換して、効率よく除去するものである。 Ever since the publication of groundbreaking research in which hydrogen and oxygen were generated by decomposing water using light irradiation using titanium dioxide electrodes, attempts have been made to utilize light energy using semiconductors. Semiconductor catalysts are characterized by their strong oxidation and reduction powers; they generate hydrogen through reduction and oxygen through oxidation of water. The present invention utilizes the oxidizing power of such semiconductors when irradiated with light to exchange heavy metal ions in wastewater with oxides and efficiently remove them.
廃水中の重金属イオンの除去法には、イオン交
換樹脂で吸着するあるいは廃水をアルカリ性にし
て、水酸化物として沈殿するなどの方法がとられ
ている。しかしイオン交換樹脂は高価であり、繰
り返し使用すると劣下してゆく。また、廃水をア
ルカリ性にすると、重金属イオンを除去した後
に、更に酸を加えて中和しなければならない、ま
たこのようにしても金属イオンの濃度の小さい場
合には、完全に除去することができない。本発明
者はこれらの欠点を克服して、しかも手軽に実行
できる重金属イオンの除去方法について研究した
結果、本発明を完成するにいたつた。 Methods for removing heavy metal ions from wastewater include adsorbing them with ion exchange resins or making the wastewater alkaline to precipitate them as hydroxides. However, ion exchange resins are expensive and deteriorate with repeated use. In addition, if wastewater is made alkaline, it is necessary to further neutralize it by adding acid after removing heavy metal ions, and even if this method is used, it may not be possible to completely remove metal ions if the concentration of metal ions is small. . The present inventor has completed the present invention as a result of research into a method for removing heavy metal ions that can overcome these drawbacks and can be carried out easily.
即ち、半導体又は貴金属を担持させた半導体を
主成分とする触媒の存在下、重金属イオンを含む
廃水に光照射し、廃水中の重金属イオンを該触媒
上に沈漬させることを特徴とする廃水中の重金属
イオンの除去方法が提供される。 That is, wastewater is characterized in that wastewater containing heavy metal ions is irradiated with light in the presence of a catalyst whose main component is a semiconductor or a semiconductor carrying a noble metal, and the heavy metal ions in the wastewater are submerged onto the catalyst. A method for removing heavy metal ions is provided.
本発明で用いる触媒は、半導体を主成分とする
ものであり、このような半導体触媒の存在下で重
金属イオンを含む廃水を光照射すると、重金属は
酸化され、半導体表面上に、重金属イオンが酸化
物として沈漬する。 The catalyst used in the present invention has a semiconductor as its main component, and when wastewater containing heavy metal ions is irradiated with light in the presence of such a semiconductor catalyst, the heavy metals are oxidized and the oxidized heavy metal ions are deposited on the semiconductor surface. Submerge as a substance.
本発明で用いる触媒は、半導体表面に沈漬した
酸化物は酸の溶液で簡単に除かれ、この処理によ
る半導体や白金の目減りがほとんどなく、触媒は
繰り返し使用することができる。従来、公害除去
に光を利用する場合には、多くは低圧水銀灯の紫
外光を用いたが、本発明では350ｍμ以上の可視
光領域の光で実施できる。従つて、容器は石英ガ
ラスを用いる必要はなく、パイレツクスガラスを
用いることができる。 In the catalyst used in the present invention, the oxide deposited on the semiconductor surface is easily removed with an acid solution, and there is almost no loss of semiconductor or platinum due to this treatment, and the catalyst can be used repeatedly. Conventionally, when using light for pollution removal, ultraviolet light from a low-pressure mercury lamp was used in most cases, but in the present invention, it can be carried out using light in the visible light range of 350 mμ or more. Therefore, the container does not need to be made of quartz glass, but can be made of pyrex glass.
本発明に用いる半導体は価電子帯と伝導帯の間
が光源の光を吸収できる大きさであり、かつ価電
子帯の位置が金属の酸化を起しうるように、酸化
電位より正であり伝導体の位置がO2＋e-→O2 -お
よび2H+＋2e-→H2の反応を起すに十分なよう
に、−0.5VsNHEより負であることが必要である。
このような条件は、価電子帯で重金属イオンを酸
化すると同時に、伝導帯の還元力で溶存酸素ある
いは水を還元し、半導体内部で生ずる電荷の分離
を効率良くするために必要である。 The semiconductor used in the present invention has a size between the valence band and the conduction band that is large enough to absorb light from the light source, and the position of the valence band is more positive than the oxidation potential and conductive so as to cause oxidation of the metal. The body position needs to be more negative than −0.5VsNHE to be sufficient to cause the reactions O 2 +e − →O 2 − and 2H + +2e − →H 2 .
Such conditions are necessary to oxidize heavy metal ions in the valence band and at the same time reduce dissolved oxygen or water with the reducing power of the conduction band, thereby efficiently separating the charges generated inside the semiconductor.
本発明で使用し得る半導体としては、例えば、
二酸化チタン、チタン酸ストロンチウム、チタン
酸バリウム等が挙げられ、通常、粉末で用いら
れ、粉子径の小さなもの程好ましい。本発明にお
いては市販の粉末状半導体をそのまま用いること
ができる。また、本発明においては、半導体に
は、助触媒として貴金属類を担持させることがで
きる。この場合、半導体に対する貴金属の担持
は、従来公知の方法、例えば、「ケミカルソサイ
テイ（Ｃ−hem.Soc、）」第100巻、第4317頁
（1978年）に記載の方法（後記実施例の記載を参
照）によつて行うことができる。担持させる貴金
属としては、白金、パラジウム、ルテニウム、金
等が挙げられ、特に白金が好ましい。また、貴金
属類の担持量は、半導体１重量部に対し0.005〜
0.2重量部、好ましくは0.02〜0.1重量部である。
光照射に用いる光としては、使用する半導体によ
り異なるが、一般的には、350ｍμ〜600ｍμの波
長の光が用いられ、例えば、二酸化チタンやチタ
ン酸ストロンチウムの場合、350ｍμ〜420ｍμの
波長の光が好ましく用いられる。光源ランプとし
ては、超高圧水銀灯や、ハロゲンランプ、キセノ
ンランプ等が用いられる。 Examples of semiconductors that can be used in the present invention include:
Examples include titanium dioxide, strontium titanate, barium titanate, etc., which are usually used in powder form, and the smaller the powder diameter, the more preferable. In the present invention, commercially available powdered semiconductors can be used as they are. Further, in the present invention, noble metals can be supported on the semiconductor as a co-catalyst. In this case, the noble metal is supported on the semiconductor using a conventionally known method, for example, the method described in "Chem.Soc," Vol. 100, p. (see description). Examples of the noble metal supported include platinum, palladium, ruthenium, gold, and the like, with platinum being particularly preferred. In addition, the amount of noble metals supported is 0.005 to 1 part by weight of semiconductor.
It is 0.2 part by weight, preferably 0.02 to 0.1 part by weight.
The light used for light irradiation varies depending on the semiconductor used, but in general, light with a wavelength of 350 mμ to 600 mμ is used. For example, in the case of titanium dioxide or strontium titanate, light with a wavelength of 350 mμ to 420 mμ is used. Preferably used. As the light source lamp, an ultra-high pressure mercury lamp, a halogen lamp, a xenon lamp, etc. are used.
本発明は、鉛、コバルト、マンガン、タリウ
ム、水銀等の重金属イオンを含む種々の廃水に適
用される。 The present invention is applicable to various wastewaters containing heavy metal ions such as lead, cobalt, manganese, thallium, and mercury.
次に本発明を実施例に基づき、更に詳細に説明
する。 Next, the present invention will be explained in more detail based on examples.
実施例 １
市販の二酸化チタン（ルチル）に白金を担持し
た白金担持触媒の0.01ｇを10×10×45mmのパイレ
ツクスガラス製のセルに入れ、0.002mol／の
鉛の溶液の３c.c.を加えた。この懸濁液をかきまぜ
ながら、500Wの高圧水銀灯の赤外部を水フイル
ターでカツトし、350ｍμ以下の紫外光を水フイ
ルターのパイレツクスガラスの窓でカツトした光
で照射した。照射後の懸濁液の上澄液を一定量取
り出して、ピリジルアゾレゾルシノールを加えて
発色させ、残存する鉛の濃度を比色分析した。30
分照射後に、鉛の94％が除去された。Example 1 0.01 g of a platinum-supported catalyst in which platinum was supported on commercially available titanium dioxide (rutile) was placed in a 10 x 10 x 45 mm Pyrex glass cell, and 3 c.c. of a 0.002 mol/lead solution was added. added. While stirring this suspension, the infrared rays of a 500W high-pressure mercury lamp were cut off with a water filter, and the ultraviolet light of less than 350 mμ was irradiated with the light filtered through the Pyrex glass window of the water filter. A certain amount of the supernatant liquid of the suspension after irradiation was taken out, pyridylazoresorcinol was added to develop a color, and the concentration of remaining lead was analyzed colorimetrically. 30
After irradiation for minutes, 94% of the lead was removed.
なお、前記白金担持半導体触媒は、「ケミカル
ソサイテイ」第100巻、第4371頁に記載の方法に
従つて、次のように製造したものである。 The platinum-supported semiconductor catalyst was produced as follows according to the method described in "Chemical Society", Vol. 100, p. 4371.
半導体（ルチル）粉末２ｇを0.1Mの塩化白金
酸水溶液に懸濁させ、これに窒素ガスを送入して
溶存酸素を除いた後、高圧水銀灯の光を照射し
て、半導体表面に白金を沈着させる。その後、白
金の沈着した半導体を別し、十分に水洗する。 Suspend 2g of semiconductor (rutile) powder in a 0.1M chloroplatinic acid aqueous solution, introduce nitrogen gas into this to remove dissolved oxygen, and then irradiate it with light from a high-pressure mercury lamp to deposit platinum on the semiconductor surface. let Thereafter, the semiconductor on which platinum has been deposited is separated and thoroughly washed with water.
実施例 ２
0.002mol／のタリウム溶液の３c.c.と、白金
担持二酸化チタンの0.01ｇを含む懸濁液に、空気
を20分間送つた後に、実施例１と同様の方法で１
時間照射した。タリウムの15％が除去された。Example 2 After blowing air for 20 minutes into a suspension containing 3 c.c. of 0.002 mol/thallium solution and 0.01 g of platinum-supported titanium dioxide,
Irradiated for hours. 15% of thallium was removed.
実施例 ３
チタン酸ストロンチウムの0.01ｇと10-3mol／
の鉛の溶液の３c.c.を含む懸濁液に空気を１時間
送つた後に、実施例１と同様の方法で２時間照射
した。鉛の55％が除去された。Example 3 0.01 g of strontium titanate and 10 -3 mol/
A suspension containing 3 c.c. of lead solution was irradiated for 2 hours in the same manner as in Example 1 after passing air through it for 1 hour. 55% of lead was removed.
実施例 ４
実施例１で得た半導体触媒を懸濁させた
10-3mol／のマンガンを含む溶液に実施例１と
同様の方法で光照射した。１時間の後にマンガン
がほとんど全て除去された。Example 4 The semiconductor catalyst obtained in Example 1 was suspended.
A solution containing 10 -3 mol/manganese was irradiated with light in the same manner as in Example 1. Almost all the manganese was removed after 1 hour.
参考例
実施例１の操作で得た触媒表面に沈漬した酸化
鉛を５％の塩酸中で１時間撹拌した。この操作に
より酸化鉛の89％が、触媒表面から除去された。Reference Example The lead oxide deposited on the surface of the catalyst obtained by the operation of Example 1 was stirred in 5% hydrochloric acid for 1 hour. This operation removed 89% of lead oxide from the catalyst surface.
実施例 ５
二酸化チタン0.015ｇと10-4molの水銀イオン３
c.c.を含む懸濁液を、実施例１と同様の方法で30分
間照射した後に水銀の82％が除去された。Example 5 0.015 g of titanium dioxide and 10 -4 mol of mercury ion 3
After irradiating the suspension containing cc for 30 minutes in the same manner as in Example 1, 82% of the mercury was removed.
Claims (1)
分とする触媒の存在下、重金属イオンを含む廃水
中に光照射し、廃水中の重金属イオンを該触媒上
に沈漬させることを特徴とする廃水中の重金属イ
オンの除去方法。1. Wastewater that is characterized by irradiating light into wastewater containing heavy metal ions in the presence of a catalyst whose main component is a semiconductor or a semiconductor supported on a noble metal, so that the heavy metal ions in the wastewater are submerged onto the catalyst. How to remove heavy metal ions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14010684A JPS6118494A (en) | 1984-07-05 | 1984-07-05 | Method for removing heavy metal ion in waste water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14010684A JPS6118494A (en) | 1984-07-05 | 1984-07-05 | Method for removing heavy metal ion in waste water |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6118494A JPS6118494A (en) | 1986-01-27 |
| JPH0117435B2 true JPH0117435B2 (en) | 1989-03-30 |
Family
ID=15261073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14010684A Granted JPS6118494A (en) | 1984-07-05 | 1984-07-05 | Method for removing heavy metal ion in waste water |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6118494A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69940491D1 (en) | 1998-09-08 | 2009-04-16 | Meidensha Electric Mfg Co Ltd | Process for the decomposition of bromic acid with photocatalysts |
-
1984
- 1984-07-05 JP JP14010684A patent/JPS6118494A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6118494A (en) | 1986-01-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |