JPH1177028A - Processing of chromium-containing wastewater - Google Patents
Processing of chromium-containing wastewaterInfo
- Publication number
- JPH1177028A JPH1177028A JP23929297A JP23929297A JPH1177028A JP H1177028 A JPH1177028 A JP H1177028A JP 23929297 A JP23929297 A JP 23929297A JP 23929297 A JP23929297 A JP 23929297A JP H1177028 A JPH1177028 A JP H1177028A
- Authority
- JP
- Japan
- Prior art keywords
- chromium
- waste liquid
- adsorbent
- hexavalent chromium
- hexavalent
- 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.)
- Pending
Links
Landscapes
- Treatment Of Liquids With Adsorbents In General (AREA)
- Removal Of Specific Substances (AREA)
- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、廃液に含まれる六
価クロムを三価クロムに還元してこれを吸着する吸着剤
を用いて除去するクロム含有廃液の処理方法に関する。
更に詳しくはメッキ工業、写真工業等における廃液など
からクロムを除去する廃液の処理方法に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a chromium-containing waste liquid in which hexavalent chromium contained in the waste liquid is reduced to trivalent chromium and removed using an adsorbent that adsorbs the trivalent chromium.
More particularly, the present invention relates to a method for treating a waste liquid for removing chromium from a waste liquid in a plating industry, a photographic industry, or the like.
【０００２】[0002]
【従来の技術】メッキ工業、写真工業等で発生する廃液
には六価クロムが含まれる。この六価クロムは酸化力が
強く、人体に暴露されれば皮膚や呼吸器を刺激し、腫瘍
や皮膚炎を生じることが知られている。そのため六価ク
ロムの生活環境への排出は厳しく制限されている。わが
国の環境基準では水道水中の六価クロム濃度を０．０５
ｐｐｍ以下に規制している。従来、六価クロムを含有す
る廃液の処理方法としては、重亜硫酸ナトリウムを用い
た六価クロムの還元法（松谷守康著「排水の公害対策」
理工学社(1987)）が知られている。この方法では廃液中
の六価クロムを重亜硫酸ナトリウムで三価クロムに還元
した後、酸性の廃液を生石灰で中和して、三価クロムの
化合物である水酸化クロム（Ｃｒ(ＯＨ)3）を沈殿さ
せ、これを濾過し回収している。しかし、この方法で
は、六価クロムの還元と中和に多量の重亜硫酸ナトリウ
ムと生石灰などの薬液を必要とする。即ち、クロム酸１
ｋｇを処理するためには重亜硫酸ナトリウムが約３ｋｇ
必要であり、中和処理した後に発生する水酸化クロムを
含むスラッジの重量は約４ｋｇである。この発生したス
ラッジからのクロムの回収はほとんど行われず、この方
法では二次廃棄物が大量に発生し、蓄積する問題点があ
った。また六価クロムを含有する廃液の別の処理方法と
して、陰イオン交換樹脂により廃液中の重クロム酸イオ
ンを回収し、これをメッキ工場に再利用する方法が提案
されている（松谷守康著「排水の公害対策」理工学社(1
987)）。この方法では回収した重クロム酸イオンを再利
用するために二次廃棄物の発生量は少ないが、六価クロ
ムの酸化力によってイオン交換樹脂性能が低下するため
に、安定して廃液を処理し続けることが難しく、かつ経
済性が低いという不具合があった。2. Description of the Related Art Wastewater generated in the plating industry, photographic industry, etc. contains hexavalent chromium. It is known that hexavalent chromium has a strong oxidizing power and, when exposed to the human body, irritates the skin and respiratory organs, causing tumors and dermatitis. Therefore, the emission of hexavalent chromium into the living environment is severely restricted. According to Japanese environmental standards, the concentration of hexavalent chromium in tap water is 0.05
It is regulated to less than ppm. Conventionally, wastewater containing hexavalent chromium has been treated using a sodium bisulfite reduction method for hexavalent chromium (Moriyasu Matsutani, "Measures for Pollution of Wastewater").
Rigakusha (1987)) is known. In this method, hexavalent chromium in the waste liquid is reduced to trivalent chromium with sodium bisulfite, and then the acidic waste liquid is neutralized with quicklime to obtain chromium hydroxide (Cr (OH) 3 ) which is a compound of trivalent chromium. , Which is collected by filtration. However, this method requires a large amount of a chemical such as sodium bisulfite and quicklime to reduce and neutralize hexavalent chromium. That is, chromic acid 1
about 3 kg of sodium bisulfite
The required weight of the sludge containing chromium hydroxide generated after the neutralization treatment is about 4 kg. Chromium is hardly recovered from the generated sludge, and this method has a problem that a large amount of secondary waste is generated and accumulated. As another method of treating a waste solution containing hexavalent chromium, a method has been proposed in which dichromate ions in the waste solution are recovered by an anion exchange resin and reused in a plating plant (Moriyasu Matsuya, " Pollution Countermeasures for Wastewater ''
987)). In this method, the amount of secondary waste generated is small because the recovered dichromate ions are reused.However, the oxidizing power of hexavalent chromium reduces the performance of the ion exchange resin. There was a problem that it was difficult to continue and the economy was low.
【０００３】一方、本出願人は、タンニン系吸着剤を用
いて重金属元素が含まれる溶液から重金属元素を分離す
る方法について特許出願した（特開平５−５００５８号
公報、特開平５−６６２９１号公報）。特開平５−５０
０５８号公報に記載の方法では、ウラン、トリウム、超
ウラン元素等のアクチニド元素、或いは鉛、カドミウ
ム、クロム、水銀、鉄等の複数種類の重金属元素が含ま
れる溶液のｐＨを調整し、この溶液とタンニン系吸着剤
とを接触させて吸着剤に所定の重金属元素を吸着させ、
この残液を上記と異なるｐＨに調整した後、この溶液と
新しいタンニン系吸着剤とを接触させて別の所定の重金
属元素を吸着させることにより、複数種類の重金属元素
を溶液から分離している。また特開平５−６６２９１号
公報に記載の方法では、縮合型タンニン粉末から安定化
したゲル状組成物からなる金属元素吸着剤を製造し、こ
の吸着剤を細分化した後、金属元素を含有する溶液に接
触させることにより、細分化した吸着剤に金属元素を吸
着している。このときの重金属元素の吸着剤への吸着
は、図４のＡ部に示すタンニンのポリフェノール性水酸
基が官能基となって、金属元素とキレート化合物を形成
するためと考えられていた（特開平５−６６２９１号公
報第６欄第４３〜４５行目参照）。On the other hand, the present applicant has filed a patent application for a method of separating a heavy metal element from a solution containing the heavy metal element using a tannin-based adsorbent (Japanese Patent Application Laid-Open Nos. 5-50058 and 5-66291). ). JP-A-5-50
In the method described in Japanese Patent No. 058, uranium, thorium, an actinide element such as a transuranium element, or lead, cadmium, chromium, mercury, and the pH of a solution containing a plurality of types of heavy metal elements such as iron are adjusted. And a tannin-based adsorbent to cause the adsorbent to adsorb a predetermined heavy metal element,
After adjusting the residual liquid to a different pH from the above, a plurality of types of heavy metal elements are separated from the solution by contacting the solution with a new tannin-based adsorbent to adsorb another predetermined heavy metal element. . Further, according to the method described in JP-A-5-66291, a metal element adsorbent comprising a stabilized gel-like composition is produced from a condensed tannin powder, and the adsorbent is finely divided and then contains a metal element. The metal element is adsorbed on the finely divided adsorbent by contact with the solution. The adsorption of the heavy metal element to the adsorbent at this time was thought to be due to the fact that the polyphenolic hydroxyl group of the tannin shown in part A of FIG. -66291, column 6, lines 43 to 45).
【０００４】[0004]
【発明が解決しようとする課題】特開平５−５００５８
号公報及び特開平５−６６２９１号公報で示された方法
では、六価クロムを含有する溶液から六価クロムを分離
する場合に、六価クロムを含む溶液をｐＨ３〜６（特開
平５−５００５８号公報第４欄第９〜１１行目参照）又
はｐＨ３．５〜１０（特開平５−６６２９１号公報第１
３欄第２８〜３０行目参照）の範囲にｐＨ調整してタン
ニン系吸着剤と接触させている。これらの方法における
上記酸性域では、吸着剤による六価クロムの三価クロム
への還元速度が著しく低い問題点があり、このために吸
着時間を極めて長くしないと、処理済みの廃液をそのま
ま河川や海洋に放出できない欠点があった。またこれら
の方法におけるアルカリ域では吸着剤に六価クロムがそ
のままの形態で吸着するため、廃液処理した吸着剤を焼
却して処分するにしても、この吸着剤は六価クロムを吸
着しているため、吸着剤の焼却灰には六価クロムが含ま
れ、この処分方法によっては新たな環境汚染が懸念され
る。またアルカリ域で吸着した処理済み廃液には六価ク
ロムが含まれることがあり、この廃液をそのまま河川や
海洋に放出できない欠点があった。Problems to be Solved by the Invention
In the method disclosed in JP-A-5-66291 and JP-A-5-66291, when hexavalent chromium is separated from a solution containing hexavalent chromium, the solution containing hexavalent chromium is pH 3 to 6 (JP-A-5-50058). No. 4, line 9 to 11) or pH 3.5 to 10 (Japanese Unexamined Patent Publication No. 5-66291, No. 1).
(See column 3, lines 28-30) and contact with the tannin-based adsorbent. In the above-mentioned acidic region in these methods, there is a problem that the rate of reduction of hexavalent chromium to trivalent chromium by the adsorbent is extremely low. Therefore, unless the adsorption time is extremely long, the treated waste liquid can be used as a river or river. There was a disadvantage that it could not be released into the ocean. Further, in the alkaline region in these methods, hexavalent chromium is adsorbed to the adsorbent in the form as it is, so even if the waste liquid treated adsorbent is incinerated and disposed of, this adsorbent adsorbs hexavalent chromium. Therefore, the incinerated ash of the adsorbent contains hexavalent chromium, and depending on this disposal method, there is a concern about new environmental pollution. In addition, the treated waste liquid adsorbed in the alkaline region sometimes contains hexavalent chromium, and this waste liquid has a drawback that it cannot be discharged to rivers and oceans as it is.
【０００５】本発明の目的は、六価クロムを吸着剤によ
り三価クロムに比較的短時間で還元して吸着し、処理後
の廃液中の六価クロムの含有量を極めて少なくし、処理
済みの廃液をそのまま河川や海洋に放出できる程度の水
質にし得るクロム含有廃液の処理方法を提供することに
ある。本発明の別の目的は、従来方法で使用した還元剤
や中和剤を必要とせず、廃液や吸着剤の二次処理を不要
とするクロム含有廃液の処理方法を提供することにあ
る。本発明の更に別の目的は、六価クロムを含有する廃
液から効率よくかつ安価に三価クロムを回収し得るクロ
ム含有廃液の処理方法を提供することにある。An object of the present invention is to reduce hexavalent chromium to trivalent chromium by an adsorbent in a relatively short time and to adsorb the same, so that the content of hexavalent chromium in the waste liquid after treatment is extremely reduced, and It is an object of the present invention to provide a method for treating a chromium-containing waste liquid that can be made to a water quality such that the waste liquid can be discharged to rivers and oceans as it is. It is another object of the present invention to provide a method for treating a chromium-containing waste liquid which does not require a reducing agent or a neutralizing agent used in the conventional method and does not require secondary treatment of the waste liquid or the adsorbent. Still another object of the present invention is to provide a method for treating a chromium-containing waste liquid that can efficiently and inexpensively recover trivalent chromium from a hexavalent chromium-containing waste liquid.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、ｐＨ１以
上３未満の強酸性域で六価クロムを含有する廃液と本発
明の吸着剤を接触させると、六価クロムが三価クロムに
比較的短時間で還元して吸着剤に吸着するという従来に
ない知見を得て、本発明に到達した。Means for Solving the Problems The present inventors contact hexavalent chromium-containing waste liquid with the adsorbent of the present invention in a strongly acidic region having a pH of 1 or more and less than 3 to convert hexavalent chromium into trivalent chromium. The present inventor has obtained an unprecedented finding that the compound is reduced and adsorbed on the adsorbent in a relatively short time, and reached the present invention.
【０００７】請求項１に係る発明は、(a) 酸性溶液中で
六価クロムを三価クロムに還元可能な水酸基、ベンゼン
環構造、炭化水素構造及びエーテル構造からなる群より
選ばれた１種又は２種以上の反応基を有し、酸化後に前
記反応基が少なくとも還元された三価クロムの吸着部位
となるクロム吸着剤を用意する工程と、(b) 六価クロム
を含有する廃液をｐＨ１以上３未満の酸性溶液に調整す
る工程と、(c) 前記ｐＨ調整した廃液と前記クロム吸着
剤とを接触させて前記廃液中の六価クロムを三価クロム
に還元して前記クロム吸着剤に吸着させる工程とを含む
クロム含有廃液の処理方法である。ｐＨ１以上３未満に
調整した、六価クロムを含有する廃液と上記吸着剤とを
接触させると、六価クロムが吸着剤の上記水酸基、ベン
ゼン環構造、炭化水素構造及びエーテル構造からなる群
より選ばれた１種又は２種以上の反応基と反応して吸着
剤が酸化され、同時に六価クロムは三価クロムに比較的
短時間で還元されて上記反応部位に吸着する。The invention according to claim 1 is characterized in that (a) one kind selected from the group consisting of a hydroxyl group capable of reducing hexavalent chromium to trivalent chromium in an acidic solution, a benzene ring structure, a hydrocarbon structure and an ether structure. Or a step of preparing a chromium adsorbent having two or more reactive groups and serving as an adsorption site for trivalent chromium in which the reactive groups have been reduced at least after oxidation, and (b) a hexavalent chromium-containing waste liquid having a pH of 1 A step of adjusting the solution to an acidic solution having a pH of less than 3; and (c) contacting the pH-adjusted waste liquid with the chromium adsorbent to reduce hexavalent chromium in the waste liquid to trivalent chromium to form the chromium adsorbent. And a step of adsorbing the chromium-containing waste liquid. When the waste liquid containing hexavalent chromium adjusted to pH 1 or more and less than 3 is brought into contact with the adsorbent, hexavalent chromium is selected from the group consisting of the above-mentioned hydroxyl group, benzene ring structure, hydrocarbon structure and ether structure of the adsorbent. The adsorbent is oxidized by reacting with one or more of the reactive groups thus obtained, and at the same time, hexavalent chromium is reduced to trivalent chromium in a relatively short time and is adsorbed at the reaction site.
【０００８】請求項２に係る発明は、請求項１に係る発
明であって、(d) クロム吸着剤と接触させた後の廃液の
六価クロムの濃度を測定する工程と、(e) 前記(d)工程
で測定した廃液中の六価クロムの濃度が所定値以上であ
るときに前記廃液のｐＨを１以上３未満に再調整した
後、前記ｐＨ再調整した廃液と前記(a)工程で用意した
クロム吸着剤又は前記(c)工程で廃液と接触したクロム
吸着剤とを再接触させて前記廃液中の六価クロムを三価
クロムに還元する工程とを更に含み、廃液中の六価クロ
ムの濃度が所定値未満になるまで、前記(d)工程と前記
(e)工程を繰返すクロム含有廃液の処理方法である。吸
着後に廃液中に六価クロムが残存する場合には、ｐＨを
再調整して廃液と吸着剤とを再接触させる。これまでク
ロムを吸着していた吸着剤に未だ六価クロムを三価クロ
ムに還元可能な水酸基、ベンゼン環構造、炭化水素構
造、エーテル構造などの反応基が残っている場合には、
吸着剤は補充せず、残っていない場合には新しい吸着剤
を補充する。これにより更に六価クロムを還元して三価
クロムとして吸着することができる。この(d)工程と(e)
工程を繰返すことにより所定の廃液の排出基準まで六価
クロムを廃液から除去することができる。従来のような
六価クロムの形態でなく、三価クロムの形態で吸着剤に
吸着しているので、これを回収すれば、回収後の吸着剤
の二次処理が不要になる。The invention according to claim 2 is the invention according to claim 1, wherein (d) a step of measuring the concentration of hexavalent chromium in the waste liquid after being brought into contact with the chromium adsorbent; When the concentration of hexavalent chromium in the waste liquid measured in the step (d) is equal to or higher than a predetermined value, the pH of the waste liquid is readjusted to 1 or more and less than 3, and the pH-adjusted waste liquid and the (a) step Re-contacting the chromium adsorbent prepared in step (b) or the chromium adsorbent contacted with the waste liquid in the step (c) to reduce hexavalent chromium in the waste liquid to trivalent chromium. Until the concentration of chromium (valent) is less than a predetermined value, the step (d) and the
This is a method for treating a chromium-containing waste liquid in which the step (e) is repeated. If hexavalent chromium remains in the waste liquid after the adsorption, the pH is readjusted and the waste liquid is brought into contact with the adsorbent again. If the adsorbent that had previously adsorbed chromium still has reactive groups such as hydroxyl groups, benzene ring structures, hydrocarbon structures, and ether structures that can reduce hexavalent chromium to trivalent chromium,
Do not replenish the sorbent; if not, replenish with new sorbent. Thereby, hexavalent chromium can be further reduced and adsorbed as trivalent chromium. This (d) step and (e)
By repeating the process, hexavalent chromium can be removed from the waste liquid up to a predetermined waste liquid discharge standard. Since the adsorbent is adsorbed in the form of trivalent chromium instead of the form of hexavalent chromium as in the conventional case, if this is recovered, the secondary treatment of the adsorbent after recovery becomes unnecessary.
【０００９】[0009]
【発明の実施の形態】次に本発明の実施の形態を説明す
る。 (1) クロム吸着剤 本発明のクロム吸着剤は、酸性溶液中で六価クロムを三
価クロムに還元可能な水酸基、ベンゼン環構造、炭化水
素構造及びエーテル構造からなる群より選ばれた１種又
は２種以上の反応基を有し、酸化後に前記反応基が少な
くとも還元された三価クロムの吸着部位となる高分子物
質である。この吸着剤を例示すれば、タンニン、フラボ
ノイド、ポリヒドロキシアントラキノン、ポリヒドロキ
シナフトキノン、メラニン、ポリビニルアルコールなど
が挙げられる。タンニンには、加水分解型タンニンや縮
合型タンニンが存在する。本発明のタンニンは加水分解
型タンニン又は縮合型タンニンの粉末を原料として作ら
れる。この加水分解型タンニンは酸、アルカリ、酵素の
作用によって、糖（普通はグルコース）、没食子酸、そ
の関連化合物等を生成し、いずれも没食子酸とその類似
化合物が糖とペプシド結合したものである。例示すれ
ば、加水分解によって主として没食子酸を生じる五倍
子タンニン、没食子タンニン等のガロタンニン、加水
分解によって没食子酸の他にエラグ酸及び没食子酸の関
連化合物を生じるミロバランタンニン、ジビジビタンニ
ン、アルガロビラタンニン等のエラグタンニン、ゲン
ノショウコ、アカメガシワ、ザクロの果皮、ミロバラン
等のエキスが挙げられる。また縮合型タンニンは酸でア
ントシアニジン系色素をつくるプロアントシアニジンを
いい、柿渋を含まない。例示すれば、ケブラチョタンニ
ン、ワットルタンニン、マングローブタンニン、スプル
ースタンニン、ガンビールタンニン、アカカテキン、カ
シワ樹皮タンニン等が挙げられる。Next, an embodiment of the present invention will be described. (1) Chromium adsorbent The chromium adsorbent of the present invention is one selected from the group consisting of a hydroxyl group capable of reducing hexavalent chromium to trivalent chromium in an acidic solution, a benzene ring structure, a hydrocarbon structure and an ether structure. Alternatively, a polymer substance having two or more types of reactive groups and serving as an adsorption site for trivalent chromium in which the reactive groups are at least reduced after oxidation. Examples of the adsorbent include tannin, flavonoid, polyhydroxyanthraquinone, polyhydroxynaphthoquinone, melanin, polyvinyl alcohol and the like. Tannins include hydrolyzable tannins and condensed tannins. The tannin of the present invention is produced using a powder of hydrolyzable tannin or condensed tannin as a raw material. This hydrolyzable tannin produces sugar (usually glucose), gallic acid, and related compounds by the action of acids, alkalis, and enzymes. In each case, gallic acid and its analogous compounds are peptidic bonds with sugar. . For example, pentaploid tannins that mainly produce gallic acid by hydrolysis, gallotannins such as gallic tannins, myrobalantannins that produce ellagic acid and gallic acid-related compounds in addition to gallic acid by hydrolysis, dividibitannin, argaroviratannin, and the like Extracts such as ellagutannin, gennoshoko, red pomegranate, pomegranate peel, myrobalan and the like. The condensed tannin refers to a proanthocyanidin that produces an anthocyanidin-based dye with an acid, and does not include persimmon juice. Examples include Kevlacho tannin, Wattle tannin, mangrove tannin, sprutannin, Gambir tannin, red catechin, oak bark tannin and the like.
【００１０】加水分解型タンニン粉末からは六価クロム
の吸着に適した加水分解型不溶性タンニンが作られる。
この不溶性タンニンはアンモニア水のようなアルカリ水
溶液に加水分解型タンニン粉末を溶解し、この溶液にア
ルデヒド水溶液を添加混合して沈殿物を生成し、この沈
殿物を加熱し、この加熱した沈殿物に鉱酸を添加混合し
た後、濾過乾燥して得られる。ここで不溶性タンニンと
は、水、酸又はアルカリのいずれに対しても不溶なタン
ニンを意味する。縮合型タンニン粉末からは六価クロム
の吸着に適したゲル状組成物のタンニンが作られる。こ
のゲル状組成物はアンモニア水に縮合型タンニン粉末を
溶解し、この溶液にアルデヒド水溶液を混合することに
より生成され、更に室温下で熟成するか又は加熱して熟
成して得られる。From the hydrolyzable tannin powder, a hydrolyzable insoluble tannin suitable for adsorption of hexavalent chromium is produced.
The insoluble tannin is prepared by dissolving the hydrolyzable tannin powder in an aqueous alkaline solution such as aqueous ammonia, adding an aqueous aldehyde solution to the solution and mixing to form a precipitate, and heating the precipitate. After adding and mixing a mineral acid, it is obtained by filtration and drying. Here, the insoluble tannin means a tannin insoluble in any of water, acid and alkali. From the condensed tannin powder, a tannin of a gel composition suitable for adsorption of hexavalent chromium is produced. This gel-like composition is produced by dissolving a condensed tannin powder in aqueous ammonia and mixing this solution with an aqueous aldehyde solution, and then aging at room temperature or aging by heating.
【００１１】(2) 六価クロム含有廃液のｐＨ調整 六価クロムを含有する廃液としては、六価クロムを大量
に利用するメッキ工業、写真工業等からの廃液、又は六
価クロムで汚染された土壌水などが挙げられる。この廃
液をｐＨ１以上３未満の範囲に調整する。好ましくはｐ
Ｈを１．５〜２．５、より好ましくはｐＨを２に調整す
る。調整したｐＨが１未満になると、高分子物質の吸着
剤の分子結合を破壊するため好ましくない。また３を超
えると、六価クロムの三価クロムへの還元速度が著しく
低下するために、本発明の目的を達成しない。ｐＨ調整
液としては強酸であればよい。過塩素酸、塩酸、硝酸、
硫酸、リン酸等が好ましい。(2) pH adjustment of hexavalent chromium-containing waste liquid As the hexavalent chromium-containing waste liquid, waste liquid from plating industry, photographic industry, etc., which uses a large amount of hexavalent chromium, or is contaminated with hexavalent chromium Soil water and the like. This waste liquid is adjusted to have a pH of 1 or more and less than 3. Preferably p
Adjust H to 1.5-2.5, more preferably to pH2. When the adjusted pH is less than 1, the molecular bond of the high molecular substance adsorbent is undesirably destroyed. On the other hand, if it exceeds 3, the reduction rate of hexavalent chromium to trivalent chromium is remarkably reduced, so that the object of the present invention is not achieved. The pH adjusting solution may be a strong acid. Perchloric acid, hydrochloric acid, nitric acid,
Sulfuric acid, phosphoric acid and the like are preferred.
【００１２】(3) ｐＨ調整した廃液とクロム吸着剤との
接触 ｐＨ調整した廃液とクロム吸着剤とを接触させる方法に
は、ｐＨ調整した廃液とクロム吸着剤とを混合撹拌する
方法、又はクロム吸着剤をカラムに充填した後、このカ
ラムにｐＨ調整した廃液を通す方法がある。前者の方法
には撹拌槽が用いられ、後者の方法には固定反応層や流
動反応層が用いられる。六価クロムの陰イオンである重
クロム酸（Ｃｒ2Ｏ7 2-）は、水素イオン（Ｈ+）濃度が
高い、ｐＨ＝１以上３未満の液中において、図４のＢ部
に示す高分子物質（ワットルタンニン）の水酸基（Ｒ-
ＯＨ）、同じくＣ部に示すベンゼン環構造、同じくＤ部
に示す炭化水素構造、同じくＥ部に示すエーテル構造
（Ｒ-Ｏ-Ｒ’）などの吸着剤構造の一部と反応する。こ
こで吸着剤の水酸基、ベンゼン環構造、炭化水素構造、
エーテル構造などは六価クロムによって酸化されて、Ｒ
-ＣＯＯＨ（カルボン酸）、Ｒ-ＣＨＯ（アルデヒド）、
Ｒ＝Ｏ（ケトン）になり、六価クロムは三価クロムに還
元されて、この水酸基、ベンゼン環構造、炭化水素構
造、エーテル構造の反応部位に三価クロムとして吸着す
る。この吸着機構を式で表すことを試みれば次の式
（１）〜（３）で表される。(3) Contact between pH-adjusted waste liquid and chromium adsorbent The method of bringing the pH-adjusted waste liquid into contact with the chromium adsorbent includes a method of mixing and stirring the pH-adjusted waste liquid and the chromium adsorbent, or a method of mixing and stirring. After the adsorbent is packed in a column, there is a method of passing a pH-adjusted waste liquid through the column. In the former method, a stirring tank is used, and in the latter method, a fixed reaction bed or a fluidized reaction bed is used. Dichromic acid (Cr 2 O 7 2− ), which is an anion of hexavalent chromium, has a high hydrogen ion (H + ) concentration in a solution having a pH of 1 to less than 3 and has a high concentration as shown in part B of FIG. Hydroxyl group (R-) of molecular substance (wattle tannin)
OH), a part of the adsorbent structure such as a benzene ring structure also shown in part C, a hydrocarbon structure also shown in part D, and an ether structure (ROR ′) shown in part E. Here, hydroxyl group of adsorbent, benzene ring structure, hydrocarbon structure,
The ether structure is oxidized by hexavalent chromium, and R
-COOH (carboxylic acid), R-CHO (aldehyde),
R = O (ketone), hexavalent chromium is reduced to trivalent chromium, and is adsorbed as trivalent chromium at the reaction site of the hydroxyl group, benzene ring structure, hydrocarbon structure, or ether structure. If an attempt is made to express this adsorption mechanism by an expression, it is expressed by the following expressions (1) to (3).
【００１３】[0013]
【化１】 Embedded image
【００１４】上記式（２）の反応の過程で液中の水素イ
オン（Ｈ+）が式（１）及び式（３）で発生する以上に
消費される。このため処理が進むにつれ、廃液のｐＨは
中性から弱アルカリ性に変化する。吸着剤に吸着した後
で廃液中に六価クロムが残存していなければ、中性から
弱アルカリ性に変化した廃液はそのまま河川や海洋に放
出することができる。またｐＨ調整した廃液中に六価ク
ロムの含有量に比して水素イオン（Ｈ+）が少なく、反
応中に水素イオン（Ｈ+）が消費し尽くされると、六価
クロムの還元は行われなくなる。この場合には、残液の
六価クロムの濃度に応じて、再度ｐＨを１以上３未満に
再調整する。この六価クロムの濃度は廃液の排出時の基
準により決められる。これまでクロムを吸着していた吸
着剤に未だ六価クロムを三価クロムに還元可能な水酸
基、ベンゼン環構造、炭化水素構造、エーテル構造など
の反応基が残っている場合には、吸着剤は補充せず、残
っていない場合には新しい吸着剤を補充する。In the course of the reaction of the formula (2), hydrogen ions (H + ) in the liquid are consumed more than the hydrogen ions (H + ) generated in the formulas (1) and (3). For this reason, as the treatment proceeds, the pH of the waste liquid changes from neutral to weakly alkaline. If hexavalent chromium does not remain in the waste liquid after being adsorbed by the adsorbent, the waste liquid changed from neutral to weakly alkaline can be discharged to rivers and oceans as it is. In addition, the amount of hydrogen ions (H + ) in the pH-adjusted waste liquid is smaller than the content of hexavalent chromium, and when hydrogen ions (H + ) are consumed during the reaction, the reduction of hexavalent chromium is performed. Disappears. In this case, the pH is readjusted to 1 or more and less than 3 again according to the concentration of hexavalent chromium in the remaining liquid. The concentration of hexavalent chromium is determined according to the standard at the time of discharging the waste liquid. If reactive groups such as hydroxyl group, benzene ring structure, hydrocarbon structure, and ether structure that can reduce hexavalent chromium to trivalent chromium still remain in the adsorbent that has adsorbed chromium, Do not replenish. If not, replenish with new adsorbent.
【００１５】(4) 吸着剤から三価クロムの回収 処理後の吸着剤には三価クロムが吸着している。この三
価クロムを回収するには三価クロムを吸着した吸着剤と
ｐＨ１以下の鉱酸とを接触させて、三価クロムを吸着剤
から溶離させる方法や、或いは三価クロムを吸着した吸
着剤を焼却して酸化クロム（Ｃｒ2Ｏ3）として回収でき
る。この酸化クロムは例えば耐火煉瓦の原料の一部に利
用することができる。(4) Recovery of trivalent chromium from the adsorbent Trivalent chromium is adsorbed on the adsorbent after the treatment. The trivalent chromium can be recovered by contacting the adsorbent with the adsorbed trivalent chromium with a mineral acid having a pH of 1 or less to elute the trivalent chromium from the adsorbent, or by adsorbing the trivalent chromium on the adsorbent Can be recovered as chromium oxide (Cr 2 O 3 ) by incineration. This chromium oxide can be used, for example, as a part of a raw material for refractory bricks.
【００１６】[0016]
【実施例】以下、本発明の実施例を比較例とともに具体
的に説明する。以下の実施例は本発明の範囲を限定する
ものではない。 ＜第１吸着剤の製造＞蒸留水２４．６ｍｌに６．２５Ｎ
のＮａＯＨ１．８ｍｌを混合した溶液に縮合型タンニン
（ワットルタンニン）粉末１６．８ｇと架橋剤として市
販のホルムアルデヒド水溶液２．４ｍｌを添加して撹拌
し溶解した。その溶液を恒温槽で８０℃に保ち、一昼夜
放置した。タンニンがアルデヒドで架橋されてゲル状組
成物が得られた。得られたゲル状組成物を蒸留水で十分
に洗浄した後、ミキサーで粉砕し３００〜６００μｍの
粒径に細分化して第１吸着剤を得た。このゲル状組成物
の含水率は６０．４％であった。EXAMPLES Examples of the present invention will be specifically described below along with comparative examples. The following examples do not limit the scope of the invention. <Production of first adsorbent> 6.25 N in 24.6 ml of distilled water
Then, 16.8 g of condensed tannin (Wattle tannin) powder and 2.4 ml of a commercially available formaldehyde aqueous solution as a cross-linking agent were added to a mixed solution of 1.8 ml of NaOH, followed by stirring and dissolving. The solution was kept at 80 ° C. in a constant temperature bath and left overnight. The tannin was cross-linked with the aldehyde to obtain a gel composition. After the obtained gel composition was sufficiently washed with distilled water, it was pulverized with a mixer and subdivided to a particle size of 300 to 600 μm to obtain a first adsorbent. The water content of this gel composition was 60.4%.
【００１７】＜第２吸着剤の製造＞縮合型タンニン（ワ
ットルタンニン）粉末の量を１４．０ｇにした以外は第
１吸着剤の製造方法と同様にして含水率６８．２％のゲ
ル状組成物からなる第２吸着剤を得た。 ＜第３吸着剤の製造＞縮合型タンニン（ワットルタンニ
ン）粉末の量を１１．２ｇにした以外は第１吸着剤の製
造方法と同様にして含水率７２．３％のゲル状組成物か
らなる第３吸着剤を得た。 ＜第４吸着剤の製造＞縮合型タンニン（ワットルタンニ
ン）粉末の量を８．４ｇにした以外は第１吸着剤の製造
方法と同様にして含水率７８．４％のゲル状組成物から
なる第４吸着剤を得た。 ＜第５吸着剤の製造＞縮合型タンニン（ワットルタンニ
ン）粉末の量を５．６ｇにした以外は第１吸着剤の製造
方法と同様にして含水率８４．３％のゲル状組成物から
なる第５吸着剤を得た。<Production of second adsorbent> A gel-like product having a water content of 68.2% was produced in the same manner as in the production of the first adsorbent except that the amount of the condensed tannin (wattle tannin) powder was changed to 14.0 g. A second adsorbent comprising the composition was obtained. <Production of Third Adsorbent> A gel composition having a water content of 72.3% was produced in the same manner as in the production method of the first adsorbent except that the amount of the condensed tannin (Wattle tannin) powder was changed to 11.2 g. Was obtained. <Production of fourth adsorbent> A gel composition having a water content of 78.4% was produced in the same manner as in the production method of the first adsorbent except that the amount of the condensed tannin (wattle tannin) powder was changed to 8.4 g. A fourth adsorbent was obtained. <Production of Fifth Adsorbent> A gel composition having a water content of 84.3% was produced in the same manner as in the production method of the first adsorbent except that the amount of the condensed tannin (wattle tannin) powder was changed to 5.6 g. A fifth adsorbent was obtained.
【００１８】＜実施例１＞上記第３吸着剤を用いて吸着
試験を行った。先ず重クロム酸ナトリウムを蒸留水に溶
解して六価クロム濃度が１０００ｐｐｍの模擬廃液を調
製した。この模擬廃液を過塩素酸でｐＨ２に調整した。
このｐＨ調整した模擬廃液２００ｍｌを撹拌槽に入れ、
３０℃に保ち、５００ｒｐｍで撹拌した。撹拌しなが
ら、第３吸着剤５ｇを撹拌槽に入れ、所定時間毎に少量
の模擬廃液を採取した。 ＜比較例１＞比較のために水酸化ナトリウムでｐＨを
８．３に調整した模擬廃液２００ｍｌを撹拌槽に入れ、
実施例１と同様に第３吸着剤５ｇを撹拌槽に入れ、所定
時間毎に少量の模擬廃液を採取した。Example 1 An adsorption test was performed using the third adsorbent. First, sodium bichromate was dissolved in distilled water to prepare a simulated waste liquid having a hexavalent chromium concentration of 1000 ppm. This simulated waste liquid was adjusted to pH 2 with perchloric acid.
200 ml of this pH-adjusted simulated waste liquid is put into a stirring tank,
It was kept at 30 ° C. and stirred at 500 rpm. While stirring, 5 g of the third adsorbent was put into a stirring tank, and a small amount of simulated waste liquid was collected every predetermined time. <Comparative Example 1> For comparison, 200 ml of the simulated waste liquid whose pH was adjusted to 8.3 with sodium hydroxide was put into a stirring tank,
In the same manner as in Example 1, 5 g of the third adsorbent was put in a stirring tank, and a small amount of simulated waste liquid was collected every predetermined time.
【００１９】＜クロム吸着性能の比較＞クロム吸着後、
実施例１のｐＨ２に調整した模擬廃液と比較例１のｐＨ
８．３に調整した模擬廃液からそれぞれ採取した液にお
ける全クロム及び六価クロムの各量を測定した。全クロ
ム量をＩＣＰ発光分析法により、また六価クロム量をジ
フェニルカルバジド法によりそれぞれ測定した。その結
果を図１に示す。図から明らかなように、実施例１のｐ
Ｈ２に調整した模擬廃液も比較例１のｐＨ８．３に調整
した模擬廃液もクロム吸着剤で処理すると、両方の模擬
廃液から検出される全クロム濃度はいずれも時間の経過
とともに減少した。また六価クロム濃度についてもいず
れも時間の経過とともに減少した。このことから、使用
した吸着剤によって模擬廃液から六価クロムを除去でき
ることを確認した。また吸着剤を入れてから４３時間後
の実施例１及び比較例１の双方のｐＨを測定したとこ
ろ、ｐＨは７．９と８．１であり、クロムの吸着により
模擬廃液のｐＨが弱アルカリ性に変化することを確認し
た。なお、実施例１ではＣｒ(VI)濃度が１８０ｐｐｍに
おいて吸着平衡に達しているが、タンニン及び酸の供給
量を増加すれば、Ｃｒ(VI)濃度を放出基準値（０．０５
ｐｐｍ）以下にすることができる。<Comparison of chromium adsorption performance>
Simulated waste liquid adjusted to pH 2 of Example 1 and pH of Comparative Example 1
Each amount of total chromium and hexavalent chromium in the liquid respectively collected from the simulated waste liquid adjusted to 8.3 was measured. The total chromium content was measured by ICP emission spectrometry, and the hexavalent chromium content was measured by diphenylcarbazide method. The result is shown in FIG. As is clear from FIG.
When both the simulated waste liquid adjusted to H2 and the simulated waste liquid adjusted to pH 8.3 of Comparative Example 1 were treated with the chromium adsorbent, the total chromium concentration detected from both simulated waste liquids decreased with time. The hexavalent chromium concentration also decreased with time. From this, it was confirmed that hexavalent chromium could be removed from the simulated waste liquid by the used adsorbent. Further, when the pH of both Example 1 and Comparative Example 1 was measured 43 hours after putting the adsorbent, the pH was 7.9 and 8.1, and the pH of the simulated waste liquid was weakly alkaline due to the adsorption of chromium. Was confirmed to change. In Example 1, the adsorption equilibrium was reached at a Cr (VI) concentration of 180 ppm. However, if the supply amounts of tannin and acid were increased, the Cr (VI) concentration was reduced to the release reference value (0.05%).
ppm) or less.
【００２０】＜吸着したクロムの分析＞実施例１及び比
較例１で使用済みのそれぞれ吸着平衡に到達した２種の
吸着剤を模擬廃液から濾別し、吸着剤粒子間に残った余
剰の水分を除去した。撹拌槽に蒸留水１００ｍｌに入
れ、別の撹拌槽に１Ｍの塩酸溶液１００ｍｌを入れた
後、実施例１で使用済みの水分除去した吸着剤をそれぞ
れ二等分し、各撹拌槽に入れ、５００ｒｐｍで撹拌し
た。また比較例１で使用済みの水分除去した吸着剤は蒸
留水の入った撹拌槽中で５００ｒｐｍで撹拌した。撹拌
してから８時間経過後と３０時間経過後において、蒸留
水又は塩酸溶液中の全クロム量、六価クロム量及び三価
クロム量を上記クロム吸着性能を比較したときと同様の
方法で評価した。三価クロム量は全クロム量から六価ク
ロム量を減じて求めた。これらの結果を表１に示す。<Analysis of adsorbed chromium> The two kinds of adsorbents used in Example 1 and Comparative Example 1, each of which reached the adsorption equilibrium, were separated from the simulated waste liquid by filtration, and excess water remaining between the adsorbent particles was removed. Was removed. After putting 100 ml of distilled water in a stirring tank and 100 ml of a 1M hydrochloric acid solution in another stirring tank, the adsorbent used in Example 1 from which water was removed was divided into two equal parts, and put in each stirring tank at 500 rpm. And stirred. The adsorbent used in Comparative Example 1 from which water had been removed was stirred at 500 rpm in a stirring tank containing distilled water. Eight hours and 30 hours after stirring, the total chromium content, hexavalent chromium content and trivalent chromium content in distilled water or hydrochloric acid solution were evaluated in the same manner as when comparing the above chromium adsorption performance. did. The amount of trivalent chromium was determined by subtracting the amount of hexavalent chromium from the total amount of chromium. Table 1 shows the results.
【００２１】[0021]
【表１】 [Table 1]
【００２２】表１から明らかなように、実施例１で使用
した吸着剤から蒸留水中に溶離したクロム量はいずれも
僅かであり、その大部分は未吸着の六価クロムであっ
た。比較例１では吸着されたクロムの約９０％が蒸留水
によって溶離され、その大部分が六価クロムであった。
一方、塩酸溶液により実施例１で使用した吸着剤から溶
離したクロムは全吸着量の約７０％であって、その全て
が三価クロムであった。この結果から、比較例１では六
価クロムは還元されずに六価クロムの形態で吸着される
のに対して、実施例１では六価クロムは吸着剤上で三価
クロムに還元されていること、及びその吸着されている
クロムのほぼ全量が三価クロムであることを確認した。As is evident from Table 1, the amount of chromium eluted from the adsorbent used in Example 1 into distilled water was small, and most of the chromium was unadsorbed hexavalent chromium. In Comparative Example 1, about 90% of the adsorbed chromium was eluted by distilled water, and most of the adsorbed chromium was hexavalent chromium.
On the other hand, the amount of chromium eluted from the adsorbent used in Example 1 with the hydrochloric acid solution was about 70% of the total adsorbed amount, and all of them were trivalent chromium. From this result, in Comparative Example 1, hexavalent chromium is adsorbed in the form of hexavalent chromium without being reduced, whereas in Example 1, hexavalent chromium is reduced to trivalent chromium on the adsorbent. It was confirmed that almost all of the adsorbed chromium was trivalent chromium.
【００２３】＜実施例２＞模擬廃液として、六価クロム
濃度が実施例１と同一の１０００ｐｐｍ重クロム酸水溶
液を用い、これを６種類の異なるｐＨ（0.85, 1.83, 2.
9, 4.19, 4.99, 8.28）に調整した。３０個のバイヤル
瓶を用意し、５個の瓶毎に同一にｐＨ調整された模擬廃
液各４０ｍｌを入れた。次いで上述した５種類の第１吸
着剤〜第５吸着剤をそれぞれ０．５ｇ採取し、３０個の
瓶に入れた。全ての瓶を３０℃の恒温槽に入れ、３昼夜
振とうした。瓶から模擬廃液を取出し、吸着剤１ｇに吸
着されたクロムのモル数ｍ1と模擬廃液１ｍｌに残留す
るクロムのモル数ｍ2を測定し、次の式（４）により分
配比Ｋdを算出した。 Ｋd ＝ ｍ1／ｍ2 …… （４） この模擬廃液の初期ｐＨと分配比Ｋdの関係を図２に示
す。図２から明らかなように、ｐＨが１．８３において
全ての吸着剤が分配比が１０００以上と高い吸着性能を
示し、ｐＨ＝２付近が最適であった。この吸着性能をク
ロムの吸着容量で表すと、ｐＨ＝３〜５の弱酸性域にお
いて乾燥したタンニン１ｇ当り１００〜１２５ｍｇのク
ロムを吸着し、ｐＨ＝１．８３の強酸性域においては乾
燥したタンニン１ｇ当り１８５〜２００ｍｇの高い値で
クロムを吸着していた。またｐＨ＝１．８３では含水率
が低い程、分配比が高い傾向を示した。<Example 2> As a simulated waste liquid, a 1000 ppm aqueous solution of dichromic acid having the same hexavalent chromium concentration as in Example 1 was used, and was used at six different pHs (0.85, 1.83, 2.
9, 4.19, 4.99, 8.28). Thirty vials were prepared, and each of the five bottles was filled with 40 ml of the same simulated waste liquid whose pH was adjusted in the same manner. Next, 0.5 g of each of the above-mentioned five types of the first to fifth adsorbents was collected and placed in 30 bottles. All bottles were placed in a thermostat at 30 ° C. and shaken for 3 days and nights. Taken out simulated waste liquid from the bottle, to measure the number of moles m 2 of chromium remaining in simulated waste liquid 1ml the moles m 1 chromium adsorbed on the adsorbent 1g, calculates a distribution ratio K d by the following equation (4) did. K d = m 1 / m 2 (4) FIG. 2 shows the relationship between the initial pH of the simulated waste liquid and the distribution ratio K d . As is clear from FIG. 2, when the pH was 1.83, all the adsorbents exhibited high adsorption performance with a distribution ratio of 1000 or more, and the optimum was around pH = 2. When this adsorption performance is represented by the adsorption capacity of chromium, 100-125 mg of chromium is adsorbed per 1 g of tannin dried in a weakly acidic region of pH = 3-5, and dried tannin is absorbed in a strongly acidic region of pH = 1.83. Chromium was adsorbed at a high value of 185 to 200 mg / g. At pH = 1.83, the lower the water content, the higher the distribution ratio.
【００２４】＜実施例３＞実施例１と同様に第３吸着剤
を用いて吸着試験を行った。先ず重クロム酸ナトリウム
を蒸留水に溶解して六価クロム濃度が１０００ｐｐｍの
模擬廃液を調製した。この模擬廃液を過塩素酸でｐＨ２
に調整した。このｐＨ調整した模擬廃液２００ｍｌを撹
拌槽に入れ、３０℃に保ち、５００ｒｐｍで撹拌した。
撹拌しながら、第３吸着剤５ｇを撹拌槽に入れ、所定時
間毎に少量の模擬廃液を採取した。採取した液における
六価クロムの量をジフェニルカルバジド法により測定し
た。その結果を図３に示す。六価クロム濃度は時間の経
過とともに減少し、この第３吸着剤によって模擬廃液か
ら六価クロムが回収可能であることを確認した。<Example 3> An adsorption test was performed using the third adsorbent in the same manner as in Example 1. First, sodium bichromate was dissolved in distilled water to prepare a simulated waste liquid having a hexavalent chromium concentration of 1000 ppm. This simulated waste solution is pH 2 with perchloric acid.
Was adjusted. 200 ml of this pH-adjusted simulated waste liquid was put into a stirring tank, kept at 30 ° C., and stirred at 500 rpm.
While stirring, 5 g of the third adsorbent was put into a stirring tank, and a small amount of simulated waste liquid was collected every predetermined time. The amount of hexavalent chromium in the collected liquid was measured by the diphenylcarbazide method. The result is shown in FIG. The hexavalent chromium concentration decreased over time, and it was confirmed that hexavalent chromium could be recovered from the simulated waste liquid by the third adsorbent.
【００２５】また吸着剤を入れてから２７時間後に少量
の模擬廃液を採取してｐＨを測定したところ、ｐＨ＝
７．９であった。このことから重クロム酸塩から酸素が
脱離したために模擬廃液中の水素イオンが消費され、廃
液のｐＨが中性から弱アルカリ性に変化することを確認
した。吸着剤を入れてから２７時間経過して吸着平衡を
確認した後、０．１Ｍの硝酸水溶液を加えて模擬廃液の
ｐＨを２に調整した。模擬廃液中の六価クロム濃度が低
下し、再び吸着剤への吸着が開始された。吸着剤を入れ
てから５３時間後の模擬廃液のｐＨは６．９であり、ほ
ぼ中性で吸着平衡になった。このことから、酸を供給し
て模擬廃液を酸性に保つことにより六価クロムの三価ク
ロムへの還元が進行し吸着剤への吸着が継続することを
確認した。Further, 27 hours after putting the adsorbent, a small amount of the simulated waste liquid was collected and the pH was measured.
7.9. From this, it was confirmed that hydrogen ions in the simulated waste liquid were consumed because oxygen was desorbed from the dichromate, and the pH of the waste liquid changed from neutral to weakly alkaline. After a lapse of 27 hours from the addition of the adsorbent and the confirmation of the adsorption equilibrium, a 0.1 M aqueous nitric acid solution was added to adjust the pH of the simulated waste liquid to 2. The hexavalent chromium concentration in the simulated waste liquid decreased, and adsorption to the adsorbent was started again. The pH of the simulated waste liquid 53 hours after the addition of the adsorbent was 6.9, which was almost neutral, and reached an adsorption equilibrium. From this, it was confirmed that the reduction of hexavalent chromium to trivalent chromium progressed and the adsorption to the adsorbent was continued by supplying acid to keep the simulated waste liquid acidic.
【００２６】[0026]
【発明の効果】以上述べたように、本発明によれば、酸
性溶液中で六価クロムを三価クロムに還元可能な水酸
基、ベンゼン環構造、炭化水素構造及びエーテル構造か
らなる群より選ばれた１種又は２種以上の反応基を有
し、酸化後に前記反応基が少なくとも還元された三価ク
ロムの吸着部位となるクロム吸着剤と、ｐＨを１以上３
未満に調整したクロム含有廃液とを接触させることによ
り、六価クロムを吸着剤により三価クロムに比較的短時
間で還元して吸着し、処理後の廃液中の六価クロムの含
有量を極めて少なくすることができる。この結果、処理
済みの廃液をそのまま河川や海洋に放出できる程度の水
質にすることができる。As described above, according to the present invention, a compound selected from the group consisting of a hydroxyl group capable of reducing hexavalent chromium to trivalent chromium in an acidic solution, a benzene ring structure, a hydrocarbon structure and an ether structure is provided. A chromium adsorbent having one or two or more reactive groups, the reactive group being an oxidation site of trivalent chromium having at least reduced after oxidation;
By contacting with a chromium-containing waste liquid adjusted to less than 3, hexavalent chromium is reduced and adsorbed to trivalent chromium in a relatively short time by an adsorbent, and the content of hexavalent chromium in the treated waste liquid is extremely reduced. Can be reduced. As a result, it is possible to make the water quality such that the treated waste liquid can be discharged to a river or ocean as it is.
【図１】実施例１及び比較例１のクロム吸着状況を示す
図。FIG. 1 is a view showing a chromium adsorption state in Example 1 and Comparative Example 1.
【図２】実施例２の模擬廃液の初期ｐＨと分配比Ｋdの
関係を示す図。FIG. 2 is a view showing the relationship between the initial pH of a simulated waste liquid of Example 2 and a distribution ratio Kd .
【図３】実施例３のクロム吸着状況を示す図。FIG. 3 is a view showing a chromium adsorption state in Example 3.
【図４】吸着剤であるワットルタンニンの推定構造式を
示す図。FIG. 4 is a view showing an estimated structural formula of wattle tannin which is an adsorbent.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中野 義夫 静岡県浜松市広沢２丁目46番44号 (72)発明者 竹下 健二 東京都町田市南つくし野２丁目14番地３ ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Nakano 2-46-44 Hirosawa, Hamamatsu-shi, Shizuoka (72) Inventor Kenji Takeshita 2- 14-3 Minami Tsukushino, Machida-shi, Tokyo
Claims (2)
ムに還元可能な水酸基、ベンゼン環構造、炭化水素構造
及びエーテル構造からなる群より選ばれた１種又は２種
以上の反応基を有し、酸化後に前記反応基が少なくとも
還元された三価クロムの吸着部位となるクロム吸着剤を
用意する工程と、 (b) 六価クロムを含有する廃液をｐＨ１以上３未満の酸
性溶液に調整する工程と、 (c) 前記ｐＨ調整した廃液と前記クロム吸着剤とを接触
させて前記廃液中の六価クロムを三価クロムに還元して
前記クロム吸着剤に吸着させる工程とを含むクロム含有
廃液の処理方法。(A) one or more reactions selected from the group consisting of a hydroxyl group capable of reducing hexavalent chromium to trivalent chromium in an acidic solution, a benzene ring structure, a hydrocarbon structure and an ether structure; A step of preparing a chromium adsorbent having a group and serving as an adsorption site for trivalent chromium in which the reactive group has been reduced at least after oxidation; and (b) an acidic solution having a pH of 1 or more and less than 3 And (c) contacting the pH-adjusted waste liquid with the chromium adsorbent to reduce hexavalent chromium in the waste liquid to trivalent chromium and adsorbing to the chromium adsorbent. Treatment of chromium-containing waste liquid.
の六価クロムの濃度を測定する工程と、 (e) 前記(d)工程で測定した廃液中の六価クロムの濃度
が所定値以上であるときに前記廃液のｐＨを１以上３未
満に再調整した後、前記ｐＨ再調整した廃液と前記(a)
工程で用意したクロム吸着剤又は前記(c)工程で廃液と
接触したクロム吸着剤とを再接触させて前記廃液中の六
価クロムを三価クロムに還元する工程とを更に含み、 廃液中の六価クロムの濃度が所定値未満になるまで、前
記(d)工程と前記(e)工程を繰返す請求項１記載のクロム
含有廃液の処理方法。(2) a step of measuring the concentration of hexavalent chromium in the waste liquid after being brought into contact with the chromium adsorbent; and (e) a step of measuring the concentration of hexavalent chromium in the waste liquid measured in the step (d). When the pH of the waste liquid is readjusted to 1 or more and less than 3 when the pH is equal to or more than a predetermined value, the pH-adjusted waste liquid and the (a)
Re-contacting the chromium adsorbent prepared in the step or the chromium adsorbent contacted with the waste liquid in the step (c) to reduce hexavalent chromium in the waste liquid to trivalent chromium. The method for treating a chromium-containing waste liquid according to claim 1, wherein the steps (d) and (e) are repeated until the concentration of hexavalent chromium becomes less than a predetermined value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23929297A JPH1177028A (en) | 1997-09-04 | 1997-09-04 | Processing of chromium-containing wastewater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23929297A JPH1177028A (en) | 1997-09-04 | 1997-09-04 | Processing of chromium-containing wastewater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH1177028A true JPH1177028A (en) | 1999-03-23 |
Family
ID=17042574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23929297A Pending JPH1177028A (en) | 1997-09-04 | 1997-09-04 | Processing of chromium-containing wastewater |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH1177028A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11169602A (en) * | 1997-12-12 | 1999-06-29 | Mitsubishi Materials Corp | Combustion device for adsorbed adsorbent |
| JP2001096104A (en) * | 1999-07-29 | 2001-04-10 | Univ Kansai | Method and apparatus for removing organic matter in liquid |
| WO2009031568A1 (en) * | 2007-09-03 | 2009-03-12 | Yuken Industry Co., Ltd. | Composition for chemical treatment and member with chemical conversion coating formed by treatment therewith |
| CN104192938A (en) * | 2014-09-11 | 2014-12-10 | 中国科学院山西煤炭化学研究所 | Method for removing hexavalent chromium from brown coal |
| CN105032374A (en) * | 2015-06-24 | 2015-11-11 | 山东大学 | Method for preparing graphene oxide-based high polymer gel capable of selectively adsorbing dyes in wastewater |
| CN105217719A (en) * | 2015-11-17 | 2016-01-06 | 梅庆波 | The treatment process of heavy metal chromium in a kind of leather-making waste water |
| CN105233812A (en) * | 2015-09-29 | 2016-01-13 | 安徽省绿巨人环境技术有限公司 | Preparation method of adsorbent for removing trivalent chromium ions from wastewater |
-
1997
- 1997-09-04 JP JP23929297A patent/JPH1177028A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11169602A (en) * | 1997-12-12 | 1999-06-29 | Mitsubishi Materials Corp | Combustion device for adsorbed adsorbent |
| JP2001096104A (en) * | 1999-07-29 | 2001-04-10 | Univ Kansai | Method and apparatus for removing organic matter in liquid |
| WO2009031568A1 (en) * | 2007-09-03 | 2009-03-12 | Yuken Industry Co., Ltd. | Composition for chemical treatment and member with chemical conversion coating formed by treatment therewith |
| JP4568863B2 (en) * | 2007-09-03 | 2010-10-27 | ユケン工業株式会社 | Composition for chemical conversion treatment and member having chemical conversion film formed by the treatment |
| JPWO2009031568A1 (en) * | 2007-09-03 | 2010-12-16 | ユケン工業株式会社 | Composition for chemical conversion treatment and member having chemical conversion film formed by the treatment |
| US8916007B2 (en) | 2007-09-03 | 2014-12-23 | Yuken Industry Co., Ltd. | Composition for chemical conversion treatment and member having a chemical conversion coating formed by the treatment |
| CN104192938A (en) * | 2014-09-11 | 2014-12-10 | 中国科学院山西煤炭化学研究所 | Method for removing hexavalent chromium from brown coal |
| CN105032374A (en) * | 2015-06-24 | 2015-11-11 | 山东大学 | Method for preparing graphene oxide-based high polymer gel capable of selectively adsorbing dyes in wastewater |
| CN105233812A (en) * | 2015-09-29 | 2016-01-13 | 安徽省绿巨人环境技术有限公司 | Preparation method of adsorbent for removing trivalent chromium ions from wastewater |
| CN105217719A (en) * | 2015-11-17 | 2016-01-06 | 梅庆波 | The treatment process of heavy metal chromium in a kind of leather-making waste water |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Wang et al. | Chromium speciation in tannery effluent after alkaline precipitation: Isolation and characterization | |
| Ghimire et al. | Adsorptive separation of arsenate and arsenite anions from aqueous medium by using orange waste | |
| DE2724954C2 (en) | Process for the decontamination of alpha and beta-active process water | |
| Xu et al. | Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: efficiency, intermediates, and toxicity | |
| Waite et al. | Oxidation and coagulation of wastewater effluent utilizing ferrate (VI) ion | |
| JPH1177028A (en) | Processing of chromium-containing wastewater | |
| CA1331226C (en) | Cation extraction process and application thereof to aqueous effluent treatment | |
| US6666972B2 (en) | Method for treating wastewater containing heavy metals with used iron oxide catalyst | |
| RU2115180C1 (en) | Adsorption technique using tannic acid | |
| AU644303B2 (en) | Method of preparing insoluble hydrolysable tannin and method of treating waste liquid with the tannin | |
| Xu et al. | Chelation of heavy metals by potassium butyl dithiophosphate | |
| Almeida et al. | Chromium precipitation from tanning spent liquors using industrial alkaline residues: a comparative study | |
| Singh et al. | The use of hematite for chromium (VI) removal | |
| DEMPSEY | The protonation, calcium complexation, and adsorption of a fractionated aquatic fulvic acid | |
| JPS6245394A (en) | Simultaneous removal of arsenic and silicon | |
| CN106045007A (en) | Water treatment method capable of controlling iodination disinfection by-products by catalyzing ozone oxidation of hardly-degradable iodinated organic matters via persulfate | |
| CA2072821C (en) | Method of preparing metal element adsorbent and method of adsorbing and separating metal element using the same | |
| RU2226726C2 (en) | Method for recovering liquid radioactive wastes of nuclear power plant | |
| CN108579658A (en) | The adsorbent of dichromate ion in a kind of removal waste water | |
| JP2004008854A (en) | Insolubilization method of heavy metal or the like in polluted soil | |
| JP2007029925A (en) | Treating method of boron-containing waste water | |
| JP2001179266A (en) | Method for treating selenium-containing water | |
| JP3144160B2 (en) | How to remove radioactive materials in water | |
| JP5497226B1 (en) | Method and apparatus for treating desalted dust containing cesium | |
| Poudel | Adsorptive Removal of Metallic and Non-Metallic Pollutants from Water by Chemically Modified Natural ION Exchanger |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040108 |
|
| A977 | Report on retrieval |
Effective date: 20051130 Free format text: JAPANESE INTERMEDIATE CODE: A971007 |
|
| A131 | Notification of reasons for refusal |
Effective date: 20051213 Free format text: JAPANESE INTERMEDIATE CODE: A131 |
|
| A02 | Decision of refusal |
Effective date: 20060411 Free format text: JAPANESE INTERMEDIATE CODE: A02 |