JPS6230838B2 - - Google Patents
Info
- Publication number
- JPS6230838B2 JPS6230838B2 JP11795177A JP11795177A JPS6230838B2 JP S6230838 B2 JPS6230838 B2 JP S6230838B2 JP 11795177 A JP11795177 A JP 11795177A JP 11795177 A JP11795177 A JP 11795177A JP S6230838 B2 JPS6230838 B2 JP S6230838B2
- Authority
- JP
- Japan
- Prior art keywords
- hexavalent chromium
- ferrous
- solution
- chromium
- liquid
- 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
Links
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 claims description 39
- 238000000034 method Methods 0.000 claims description 17
- 239000000243 solution Substances 0.000 claims description 13
- 239000000725 suspension Substances 0.000 claims description 7
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 6
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 16
- 239000007788 liquid Substances 0.000 description 15
- 239000011651 chromium Substances 0.000 description 12
- 239000002351 wastewater Substances 0.000 description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 7
- 229910052804 chromium Inorganic materials 0.000 description 7
- 238000006722 reduction reaction Methods 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 4
- 235000003891 ferrous sulphate Nutrition 0.000 description 3
- 239000011790 ferrous sulphate Substances 0.000 description 3
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000004277 Ferrous carbonate Substances 0.000 description 1
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- DUPIXUINLCPYLU-UHFFFAOYSA-N barium lead Chemical class [Ba].[Pb] DUPIXUINLCPYLU-UHFFFAOYSA-N 0.000 description 1
- 159000000009 barium salts Chemical class 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- IMBKASBLAKCLEM-UHFFFAOYSA-L ferrous ammonium sulfate (anhydrous) Chemical compound [NH4+].[NH4+].[Fe+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O IMBKASBLAKCLEM-UHFFFAOYSA-L 0.000 description 1
- RAQDACVRFCEPDA-UHFFFAOYSA-L ferrous carbonate Chemical compound [Fe+2].[O-]C([O-])=O RAQDACVRFCEPDA-UHFFFAOYSA-L 0.000 description 1
- 235000019268 ferrous carbonate Nutrition 0.000 description 1
- 229960004652 ferrous carbonate Drugs 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 229940062993 ferrous oxalate Drugs 0.000 description 1
- 229940116007 ferrous phosphate Drugs 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 description 1
- 229910000015 iron(II) carbonate Inorganic materials 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- 229910000155 iron(II) phosphate Inorganic materials 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- SDEKDNPYZOERBP-UHFFFAOYSA-H iron(ii) phosphate Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SDEKDNPYZOERBP-UHFFFAOYSA-H 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
Landscapes
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Removal Of Specific Substances (AREA)
Description
本発明は６価クロムを含む溶液又は懸濁液中の
６価クロムを連続的に還元処理する方法に関す
る。
６価クロムを含む溶液又は懸濁液から６価クロ
ムを除去する方法は、特に有害な６価クロムを含
む廃水の代表であるクロムメツキ廃水やクロメー
ト処理廃水、ソルト廃液、金属表面処理廃水など
の処理方法として広く研究されている。従来の主
な６価クロムの除去方法としては、廃水中に適当
な還元剤、例えば亜硫酸ガス、亜硫酸塩、第一鉄
塩などを用いて６価クロムを３価クロムに還元し
た後不溶性の化合物として沈澱除去したり、バリ
ウム塩や鉛塩を用いて６価クロムイオンから直接
不溶性の化合物を沈澱させたりする方法が知られ
ている。
本発明者らは、第一鉄塩を用いる６価クロムの
還元処理プロセスについて鋭意研究を進めて来
た。第一鉄塩を用いる、従来の６価クロムの還元
処理プロセスは、６価クロムを含む液中に大過剰
の第一鉄塩を添加しなければ廃液中の６価クロム
を完全に除去できないため大量の第一鉄塩をロス
するばかりでなく、生成スラツジ量が増えるとい
う問題があつた。
従つて、本発明の目的は、前述の従来の６価ク
ロムの還元処理方法の欠点を排除し、ほぼ理論量
の第一鉄塩を添加するだけで廃液その他の液中に
含まれる６価クロムを実質上完全に除去する６価
クロムの還元処理方法を提供することにある。
本発明の他の目的は、６価クロムを含む溶液又
は懸濁液中の６価クロムを連続的に還元処理する
６価クロムの連続処理方法を提供することにあ
る。
本発明に係る６価クロムの連続還元処理方法
は、６価クロムを含む溶液又は懸濁液中の６価ク
ロムを連続還元処理するに当り、前記溶液又は懸
濁液のPHを約4.5〜約8.5、好ましくは約5.5〜約
7.2の範囲内に保ちながら、系の酸化還元電位を
約−50〜約−150mV、好ましくは約−50〜約−
100mV、の範囲内に保持するよう第一鉄イオン
含有液を制御注入することから構成される。
液のPHが4.5未満の場合には、酸化還元電位
（ORP）の当量点附近での変化がシヤープでな
く、目的とする、実質的に理論量の第一鉄塩の添
加による６価クロムの連続還元処理プロセスが達
成できない。液のPHが8.5を越えた場合には、６
価クロムと第一鉄塩との反応効率が悪く、大過剰
の第一鉄塩を添加する必要があり好ましくない。
然るに、本発明に従えば、液のPHを約4.5〜約
8.5、好ましくは約5.5〜約7.2の範囲内に制御して
６価クロムの第一鉄塩による還元反応を実施する
ので、当量点附近で酸化還元電位がシヤープに変
化し（酸化還元電位の落差が大きく）、酸化還元
電位を約−50〜約−150mVの範囲内に保持する
ように６価クロム含有液に第一鉄塩を制御注入す
ることによつて液中の６価クロムを連続プロセス
で完全に還元することができる。液の酸化還元電
位をかかる値に制御することによつて、第一鉄塩
の使用量を理論量の1.5倍以内に抑えることがで
きる。
本発明方法で用いる第一鉄塩の種類には、特に
限定はなく、例えば、硫酸第一鉄が最も一般的で
あるが、他に水溶性塩では、塩化第一鉄、硫酸第
一鉄アンモニウム、硝酸第一鉄等、難溶性塩で
は、水酸化第一鉄、炭酸第一鉄、リン酸第一鉄、
シユウ酸第一鉄、硫化第一鉄等の一般の第一鉄塩
を使用できる。またこれらの純粋溶液に限らず、
これらの第一鉄塩を含有する一般廃液、例えば製
鉄工業等の酸洗廃液、鋼業の鉄鉱石廃水等も使用
できる。
本発明方法における、６価クロムの処理機構は
６価クロムを第一鉄イオンにより、３価クロムに
還元すると同時に、３価クロムを難溶性の水酸化
物として、凝集沈澱分離するものであり、基本反
応式は次式の通りである。
Cr＋3Fe2+→Cr3+＋3Fe3+ ……(1)
Cr3+＋3OH-→Cr（OH）3↓ ……(2)
Fe3+＋3OH-→Fe（OH）3↓ ……(3)
以下に本発明の実施例を説明する。
実施例 １
撹拌機、PHメータ（電気化学計器製MG―７
型、ガラス電極）およびORPメータ（電気化学
計器製HG―２型）、甘コウ基準電極および合金指
示電極）を備えた容積20の反応槽中で
K2CrO7水溶液（６価クロム濃度として40mg／
）中の６価クロムの連続還元処理実験を行つ
た。液のPHを水酸化ナトリウムを用いて約７に制
御し乍ら、硫酸第一鉄水溶液（FeSO4濃度3.5重
量％、PH１）を系のORPが約−100mVになるよ
う制御注入した。K2Cr2O7水溶液の反応槽への供
給速度は0.6／minであつた。反応槽出口液中
の６価クロム濃度を、JIS―Ｋ―0102に準拠して
測定したところ、６価クロムは検出されなかつ
た。
上記実験において液のPHを約11にした以外は全
く同様にしてK2Cr2O7水溶液の連続還元実験を行
なつたところ、出口液中の６価クロム濃度は７
mg／であつた。
また液のPHを約３に保ち乍ら、上記実験を繰り
返したところ、硫酸第一鉄水溶液の添加による酸
化還元電位の変化が顕著に見られず、大過剰の硫
酸第一鉄水溶液を加えてもORP制御不能であつ
た。
実施例 ２
実施例１で述べたようにしてソルト廃水（全ク
ロム38.3mg／、６価クロム23mg／、PH11.6）
に含まれる６価クロムの連続還元処理を行つた。
系のPHおよびORPは下表に示すような値に制御
して実験した。液のPHは硫酸又は苛性ソーダ水溶
液を用いて調整した。出口液中の６価クロム濃度
は下表に示す通りであつた。
The present invention relates to a method for continuously reducing hexavalent chromium in a solution or suspension containing hexavalent chromium. A method for removing hexavalent chromium from a solution or suspension containing hexavalent chromium is a method for treating chromium plating wastewater, chromate treatment wastewater, salt wastewater, metal surface treatment wastewater, etc., which are representative of wastewater containing particularly harmful hexavalent chromium. This method has been widely studied. The main conventional method for removing hexavalent chromium is to reduce hexavalent chromium to trivalent chromium using an appropriate reducing agent such as sulfur dioxide gas, sulfite, ferrous salt, etc. in wastewater, and then remove the insoluble compound. There are known methods in which insoluble compounds are directly precipitated from hexavalent chromium ions using barium salts or lead salts. The present inventors have been conducting intensive research on a reduction treatment process for hexavalent chromium using ferrous salt. The conventional reduction treatment process for hexavalent chromium using ferrous salt cannot completely remove hexavalent chromium from the waste liquid unless a large excess of ferrous salt is added to the liquid containing hexavalent chromium. There was a problem that not only a large amount of ferrous salt was lost, but also the amount of sludge produced increased. Therefore, an object of the present invention is to eliminate the drawbacks of the conventional hexavalent chromium reduction treatment method described above, and to reduce hexavalent chromium contained in waste liquids and other liquids by simply adding approximately the stoichiometric amount of ferrous salt. An object of the present invention is to provide a method for reducing hexavalent chromium, which substantially completely removes hexavalent chromium. Another object of the present invention is to provide a continuous treatment method for hexavalent chromium, which continuously reduces hexavalent chromium in a solution or suspension containing hexavalent chromium. In the continuous reduction treatment method for hexavalent chromium according to the present invention, in continuously reducing hexavalent chromium in a solution or suspension containing hexavalent chromium, the pH of the solution or suspension is reduced to about 4.5 to about 8.5, preferably about 5.5 to about
7.2, while maintaining the redox potential of the system from about -50 to about -150 mV, preferably from about -50 to about -
It consists of a controlled injection of a ferrous ion-containing solution to maintain it within a range of 100 mV. When the pH of the liquid is less than 4.5, the change in the oxidation-reduction potential (ORP) near the equivalence point is not sharp, and the desired change in hexavalent chromium due to the addition of a substantially stoichiometric amount of ferrous salt is observed. A continuous reduction treatment process cannot be achieved. If the pH of the liquid exceeds 8.5,
The reaction efficiency between the valent chromium and the ferrous salt is poor, and it is necessary to add a large excess of the ferrous salt, which is not preferable.
However, according to the present invention, the pH of the liquid is reduced to about 4.5 to about
8.5, preferably within the range of about 5.5 to about 7.2, and the reduction reaction of hexavalent chromium with ferrous salt is carried out, so the redox potential changes sharply near the equivalence point (the drop in redox potential ), the hexavalent chromium in the liquid is removed by a continuous process by controlled injection of ferrous salt into the hexavalent chromium-containing liquid to maintain the redox potential within the range of about -50 to about -150 mV. can be fully refunded. By controlling the redox potential of the liquid to such a value, the amount of ferrous salt used can be kept within 1.5 times the theoretical amount. The type of ferrous salt used in the method of the present invention is not particularly limited; for example, ferrous sulfate is the most common, but other water-soluble salts include ferrous chloride, ferrous ammonium sulfate, etc. , ferrous nitrate, and other sparingly soluble salts include ferrous hydroxide, ferrous carbonate, ferrous phosphate,
Common ferrous salts such as ferrous oxalate and ferrous sulfide can be used. In addition to these pure solutions,
General wastewater containing these ferrous salts, such as pickling wastewater from the iron industry, iron ore wastewater from the steel industry, etc. can also be used. The processing mechanism for hexavalent chromium in the method of the present invention is to reduce hexavalent chromium to trivalent chromium using ferrous ions, and at the same time, to separate trivalent chromium by coagulation and precipitation as a hardly soluble hydroxide. The basic reaction formula is as follows. Cr＋3Fe 2+ →Cr 3+ +3Fe 3+ ……(1) Cr 3+ ＋3OH - →Cr(OH) 3 ↓ ……(2) Fe 3+ ＋3OH - →Fe(OH) 3 ↓ ……(3) Below Examples of the present invention will be described below. Example 1 Stirrer, PH meter (MG-7 manufactured by Denki Kagaku Keiki)
K 2 CrO 7 aqueous solution (40 mg as hexavalent chromium concentration) in a reaction tank with a volume of 20 equipped with an ORP meter (Model HG-2 manufactured by Denki Kagaku Keiki), Amakou reference electrode and alloy indicator electrode). /
) was conducted to continuously reduce hexavalent chromium. While the pH of the solution was controlled to about 7 using sodium hydroxide, a ferrous sulfate aqueous solution (FeSO 4 concentration 3.5% by weight, PH 1) was controlled and injected so that the ORP of the system was about −100 mV. The feed rate of the K 2 Cr 2 O 7 aqueous solution to the reaction tank was 0.6/min. When the concentration of hexavalent chromium in the reaction tank outlet liquid was measured in accordance with JIS-K-0102, no hexavalent chromium was detected. A continuous reduction experiment of K 2 Cr 2 O 7 aqueous solution was carried out in exactly the same manner as in the above experiment except that the pH of the liquid was set to about 11, and the concentration of hexavalent chromium in the outlet liquid was 7.
mg/. In addition, when the above experiment was repeated while maintaining the pH of the solution at approximately 3, no significant change in the redox potential was observed due to the addition of the ferrous sulfate aqueous solution. ORP was also out of control. Example 2 Salt wastewater was prepared as described in Example 1 (total chromium 38.3 mg/, hexavalent chromium 23 mg/, PH 11.6)
The hexavalent chromium contained in the chromium was continuously reduced.
The experiment was conducted by controlling the PH and ORP of the system to the values shown in the table below. The pH of the liquid was adjusted using sulfuric acid or aqueous caustic soda solution. The concentration of hexavalent chromium in the outlet liquid was as shown in the table below.
【表】【table】
【表】
☆ 比較実験
[Table] ☆ Comparative experiment
Claims (1)
ロムを連続還元処理するに当り、前記溶液又は懸
濁液のPHを約4.5〜約8.5の範囲内に保ちながら、
系の酸化還元電位を約−50〜約−150mVの範囲
内に保持するよう第一鉄イオン含有液を制御注入
することを特徴とする６価クロムの連続処理法。 ２ 前記PH範囲が約5.5〜約7.2である特許請求の
範囲第１項記載の処理法。 ３ 前記酸化還元電位の範囲が約−50〜約−
100mVである特許請求の範囲第１項もしくは第
２項記載の処理法。[Claims] 1. In continuously reducing hexavalent chromium in a solution or suspension containing hexavalent chromium, while maintaining the pH of the solution or suspension within the range of about 4.5 to about 8.5. ,
A method for continuous treatment of hexavalent chromium, characterized by controlling injection of a ferrous ion-containing solution so as to maintain the redox potential of the system within the range of about -50 to about -150 mV. 2. The treatment method according to claim 1, wherein the PH range is about 5.5 to about 7.2. 3 The range of the redox potential is about -50 to about -
The treatment method according to claim 1 or 2, wherein the voltage is 100 mV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11795177A JPS5451972A (en) | 1977-10-03 | 1977-10-03 | Method of continuously treating sexivalent chrome |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11795177A JPS5451972A (en) | 1977-10-03 | 1977-10-03 | Method of continuously treating sexivalent chrome |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5451972A JPS5451972A (en) | 1979-04-24 |
| JPS6230838B2 true JPS6230838B2 (en) | 1987-07-04 |
Family
ID=14724263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11795177A Granted JPS5451972A (en) | 1977-10-03 | 1977-10-03 | Method of continuously treating sexivalent chrome |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5451972A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3437686C2 (en) * | 1984-10-15 | 1986-10-02 | Hoechst Ag, 6230 Frankfurt | Process for the reduction of metal ions in aqueous solutions |
| US5292435A (en) * | 1992-09-28 | 1994-03-08 | Klaus Schwitzgebel | Equipment and process for solid waste minimization in chromium and heavy metal removal from groundwater |
| US5427692A (en) * | 1993-11-29 | 1995-06-27 | General Electric Company | Removal of chromium from solution using ferrous sulfate and barium nitrate |
| US6607651B2 (en) | 1998-09-10 | 2003-08-19 | Cws Parts Company | Process and system for treating the discharge stream from an ion exchanger |
-
1977
- 1977-10-03 JP JP11795177A patent/JPS5451972A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5451972A (en) | 1979-04-24 |
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