JPS623898B2 - - Google Patents
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- Publication number
- JPS623898B2 JPS623898B2 JP53161932A JP16193278A JPS623898B2 JP S623898 B2 JPS623898 B2 JP S623898B2 JP 53161932 A JP53161932 A JP 53161932A JP 16193278 A JP16193278 A JP 16193278A JP S623898 B2 JPS623898 B2 JP S623898B2
- Authority
- JP
- Japan
- Prior art keywords
- iodine
- residual chlorine
- electrode
- solution
- concentration
- 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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- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 claims description 54
- 229910052740 iodine Inorganic materials 0.000 claims description 52
- 239000011630 iodine Substances 0.000 claims description 51
- 239000000460 chlorine Substances 0.000 claims description 50
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 44
- 229910052801 chlorine Inorganic materials 0.000 claims description 44
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 41
- 239000007788 liquid Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 20
- 239000000243 solution Substances 0.000 claims description 18
- 239000012085 test solution Substances 0.000 claims description 18
- 238000012360 testing method Methods 0.000 claims description 17
- 239000012528 membrane Substances 0.000 claims description 16
- -1 iodine ions Chemical class 0.000 claims description 10
- 239000003115 supporting electrolyte Substances 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 20
- 238000001514 detection method Methods 0.000 description 12
- XMBWDFGMSWQBCA-UHFFFAOYSA-M iodide Chemical compound [I-] XMBWDFGMSWQBCA-UHFFFAOYSA-M 0.000 description 12
- 229910052697 platinum Inorganic materials 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 230000002452 interceptive effect Effects 0.000 description 4
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- NUIURNJTPRWVAP-UHFFFAOYSA-N 3,3'-Dimethylbenzidine Chemical compound C1=C(N)C(C)=CC(C=2C=C(C)C(N)=CC=2)=C1 NUIURNJTPRWVAP-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000011088 calibration curve Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000003411 electrode reaction Methods 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- WQDWFCGISCUJEK-UHFFFAOYSA-N [Cl].ClN Chemical compound [Cl].ClN WQDWFCGISCUJEK-UHFFFAOYSA-N 0.000 description 1
- 238000003928 amperometric titration Methods 0.000 description 1
- GCPXMJHSNVMWNM-UHFFFAOYSA-N arsenous acid Chemical compound O[As](O)O GCPXMJHSNVMWNM-UHFFFAOYSA-N 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000002496 iodine Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- JLKDVMWYMMLWTI-UHFFFAOYSA-M potassium iodate Chemical compound [K+].[O-]I(=O)=O JLKDVMWYMMLWTI-UHFFFAOYSA-M 0.000 description 1
- 239000001230 potassium iodate Substances 0.000 description 1
- 235000006666 potassium iodate Nutrition 0.000 description 1
- 229940093930 potassium iodate Drugs 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
Description
【発明の詳細な説明】
本発明は、被検液に緩衝液又は酸を加えて所定
のPHに調節し、さらに、適当量のヨウ化カリウム
溶液を加えて被検液中の残留塩素に対して一定比
率の遊離ヨウ素を生ぜしめ、この遊離ヨウ素の検
出により、主として上水道中の残留塩素の濃度を
測定する方法に関する。主として上水道中の残留
塩素測定法として、従来は、
オルト・トリジン法又はオルト・トリジン−
亜ひ酸法
ヨウ素滴定法
電流滴定法
回転白金電極によるポーラログラフ法
があるが、上記では塩素標準比色液をもとに比
色操作を行なうさいに個人差を生じ、妨害成分の
影響により信頼性が低く、かつオルト・トリジン
が有害である。では操作が、繁雑で、かつ低濃
度の残留塩素測定には不適当である。では、操
作が煩雑である。DETAILED DESCRIPTION OF THE INVENTION The present invention involves adding a buffer solution or an acid to a test solution to adjust the pH to a predetermined value, and then adding an appropriate amount of potassium iodide solution to remove residual chlorine in the test solution. This invention mainly relates to a method for measuring the concentration of residual chlorine in water supply by generating a certain ratio of free iodine and detecting this free iodine. Traditionally, the ortho-tolidine method or ortho-tolidine method was used to mainly measure residual chlorine in water supplies.
Arsenous acid method Iodometric titration method Amperometric titration method There are polarographic methods using a rotating platinum electrode, but in the above method, individual differences occur when performing colorimetric operations based on a chlorine standard colorimetric solution, and reliability is poor due to the influence of interfering components. is low and ortho-tolidine is harmful. This method requires complicated operations and is unsuitable for measuring residual chlorine at low concentrations. However, the operation is complicated.
等の、欠点を有し、現在工業的に広く用いられ
ている方法はである。 These are the methods that are currently widely used industrially and have drawbacks.
この回転白金電極によるポーラログラフ法で
は、被検液に適当なPH下でヨウ化カリウムを加
え、被検液中の残留塩素と反応させると、下記の
(1)〜(4)式によつて、残留塩素と等量のヨウ素を生
ずる。 In this polarographic method using a rotating platinum electrode, potassium iodide is added to the test solution under an appropriate pH and reacts with the residual chlorine in the test solution, resulting in the following:
Equations (1) to (4) produce iodine in an amount equivalent to residual chlorine.
遊離有効塩素
Cl2＋2I-→I2＋2Cl- ……(1)
結合性有効塩素（クロラミン）
NH2Cl＋2I-＋2H+→I2＋NH4Cl ……(2)
NHCl2＋4I-＋3H+→2I2＋NH4Cl＋Cl-
……(3)
NCl3＋6I-＋4H+→3I2＋NH4Cl＋2Cl-
……(4)
このヨウ素を電解還元して、流れる電流を測定
し、その電流値から残留塩素を求めるものであ
る。この電解還元電流は、白金カソード電極で次
なる反応が生ずる事によつて発生する。Free available chlorine Cl 2 +2I - →I 2 +2Cl - ...(1) Bound available chlorine (chloramine) NH 2 Cl+2I - +2H + →I 2 +NH 4 Cl ...(2) NHCl 2 +4I - +3H + →2I 2 +NH 4 Cl＋Cl - ...(3) NCl 3 +6I - +4H + →3I 2 +NH 4 Cl+2Cl - ...(4) This iodine is electrolytically reduced, the flowing current is measured, and residual chlorine is determined from the current value. It is. This electrolytic reduction current is generated by the following reaction occurring at the platinum cathode electrode.
I2＋2e-→2I- ……(5)
しかし、白金カソード電極において(5)の反応が
定常的に生じる為には即ち一定濃度のヨウ素溶液
において常に一定の電流が流れる為には、白金カ
ソード電極を回転させる必要がある。従つて、現
在工業的に広く使用されている残留塩素測定装置
は、第１図に示すような構造のものがほとんどで
ある。（尚、同図において、１は被検液タンク、
２は試薬タンク、P1，P2はポンプ、３は撹拌翼、
M1，M2はモータ、４はカソード電極、５はアノ
ード電極、６は仕切板、Ａは電流計である。）
ところがこの従来装置では次の欠点がある。 I 2 +2e - →2I - ...(5) However, in order for the reaction (5) to occur steadily at the platinum cathode electrode, that is, for a constant current to always flow in an iodine solution of a constant concentration, the platinum cathode electrode must be It is necessary to rotate the electrode. Therefore, most residual chlorine measuring devices currently in widespread industrial use have a structure as shown in FIG. (In the same figure, 1 is the test liquid tank,
2 is a reagent tank, P 1 and P 2 are pumps, 3 is a stirring blade,
M 1 and M 2 are motors, 4 is a cathode electrode, 5 is an anode electrode, 6 is a partition plate, and A is an ammeter. ) However, this conventional device has the following drawbacks.
カソード電極(4)を回転させる為の複雑な機構
を必要とする。 A complicated mechanism is required to rotate the cathode electrode (4).
工業用分析計として、その心臓部となる検出
器が複雑な可動部分を有するので信頼性の低下
をきたす。 As an industrial analyzer, the detector, which is the heart of the analyzer, has complicated moving parts, resulting in a decrease in reliability.
最大の欠点は、核心となる前記(5)式の電極反
応を行なわせる電極が、多種多様な妨害物質を
含む被検液に直接さらされる点にある。 The biggest drawback is that the electrode, which carries out the core electrode reaction of formula (5) above, is directly exposed to the test liquid containing a wide variety of interfering substances.
即ち、(5)式の電極反応が選択的に行なわれね
ばならないのに、被検液中の電解可能な妨害物
質に対しても同様な還元反応が生じ、その結果
大きな正の誤差を生じる事になる。 In other words, although the electrode reaction in equation (5) must be carried out selectively, a similar reduction reaction occurs for electrolyzable interfering substances in the test solution, resulting in a large positive error. become.
また、一般に電解電極の表面状態によつて電
解電流は大きく影響される。従つて、直接被検
液に電極を接するこの装置の場合、電極の汚染
が大問題となる。従つて電極を清浄に保つ為
に、ブラシ、ガラスビーズ、超音波、水ジエツ
ト洗浄などの附加的な機構を分析計に設けなけ
ればならない。 Further, in general, the electrolytic current is greatly influenced by the surface condition of the electrolytic electrode. Therefore, in the case of this device in which the electrodes are brought into direct contact with the sample liquid, contamination of the electrodes becomes a serious problem. Therefore, additional mechanisms such as brushes, glass beads, ultrasound, water jet cleaning, etc. must be provided in the analyzer to keep the electrodes clean.
回転機構、洗浄機構などの複雑な構造を有し
ている為に、検出部の容積が大きくなる結果、
滞留時間が長くなり、応答時間が遅い。またそ
の反応時間を早める為に被検液を多量に流すの
で、必然的に多量の試薬を添加する必要があ
り、長時間連続運転する為には非常に大きな試
薬貯留槽が必要となつて来る。その結果、装置
が大掛かりになりがちとなる。 Because it has a complicated structure such as a rotation mechanism and a cleaning mechanism, the volume of the detection part becomes large.
Longer residence time and slower response time. In addition, since a large amount of the test solution is flowed in order to speed up the reaction time, it is necessary to add a large amount of reagent, and a very large reagent storage tank is required for continuous operation for a long time. . As a result, the device tends to be bulky.
本発明は、上記従来欠点を解消する新規有用な
残留塩素測定方法を提供するもので、ヨウ化カリ
ウム溶液を被検液に添加し、残留塩素と当量のヨ
ウ素を生ぜしめるに至る過程については、前記従
来の回転白金電極によるポーラログラフ法とほぼ
同一であるが、その後の遊離ヨウ素検出方法を全
く異にするものであり、本発明の要旨は、
(1) 被検液に緩衝液又は酸を加えて所定のPHに調
節し、さらに、適当量のヨウ化カリウム溶液を
加えて被検液中の残留塩素に対して一定比率の
遊離ヨウ素を生ぜしめ、この遊離ヨウ素を、ガ
ス透過膜を用いて隔膜式ポーラログラフ電極に
て検出し該電極の電流出力でもつて被検液中の
残留塩素を測定する残留塩素測定方法。 The present invention provides a new and useful method for measuring residual chlorine that eliminates the above-mentioned conventional drawbacks.The process of adding potassium iodide solution to a test liquid and producing iodine equivalent to the residual chlorine is as follows: Although it is almost the same as the conventional polarographic method using a rotating platinum electrode, the subsequent free iodine detection method is completely different, and the gist of the present invention is as follows: Then, add an appropriate amount of potassium iodide solution to generate free iodine at a certain ratio to the residual chlorine in the test solution, and remove this free iodine using a gas permeable membrane. A residual chlorine measurement method that detects residual chlorine in a test liquid using a diaphragm-type polarographic electrode and measures the current output of the electrode.
(2) 上記(1)の測定方法において、隔膜式ポーラロ
グラフ電極の支持電解液としてヨウ素イオンを
主成分とする溶液を用いることを特徴とするも
の。(2) The measuring method of (1) above, characterized in that a solution containing iodine ions as a main component is used as the supporting electrolyte of the diaphragm type polarographic electrode.
(3) 上記(1)又は(2)の測定方法において被検液のヨ
ウ化カリウム濃度が５×10-4〜５×10-2mol／
となるように、ヨウ化カリウム溶液を被検液
に加えることを特徴とするもの、にある。(3) In the measurement method of (1) or (2) above, the potassium iodide concentration of the test solution is 5 × 10 -4 to 5 × 10 -2 mol/
A potassium iodide solution is added to the test solution so that
次に本発明の原理を第２図に基づいて説明す
る。被検液７にヨウ化カリウム水溶液を添加し、
残留塩素に対して一定比率の遊離ヨウ素を生ぜし
めると、この遊離ヨウ素は、液体中に溶存するガ
スと考える事が出来るので、第２図に示す如きガ
ス透過膜８を有する隔膜式ポーラログラフ電極９
を被検液７中に浸漬すると、ガス状の遊離ヨウ素
はガス透過膜８を透過し、隔膜式ポーラログラフ
電極９内に達する事ができる。一方、ガス透過膜
８の電極内部側の面には、ほとんど膜と密着する
様にカソード電極１０が設置され、かつ、膜８と
カソード電極１０の間隔内には毛管現象により支
持電解液３１が薄膜状に保持されている。従つ
て、ガス透過膜８を透過して来た遊離ヨウ素は、
薄膜状の支持電解液層を拡散して、カソード電極
１０に至る。さらに、カソード電極１０とアノー
ド電極１１間には外部より電解電圧Ｅ〔Ｖ〕が印
加されている為に、カソード電極面において前述
した(5)式の電解反応が生じ、外部回路に反応した
遊離ヨウ素の量に比例した電流が流れる訳であ
る。また、ガス透過膜を透過する遊離ヨウ素の量
は、物理的条件が同一の場合、被検液中の遊離ヨ
ウ素濃度に比例する。従つて、カソード電極１０
に到達し前記(5)式の電解反応を受けるヨウ素の量
は、被検液中の遊離ヨウ素濃度に比例する。即
ち、外部回路に流れる電流は、被検液中の遊離ヨ
ウ素濃度に比例する訳であり、結局被検液中の残
留塩素濃度が求められる事になる。 Next, the principle of the present invention will be explained based on FIG. Add potassium iodide aqueous solution to test solution 7,
When free iodine is generated at a certain ratio to residual chlorine, this free iodine can be considered as a gas dissolved in the liquid. Therefore, a membrane-type polarographic electrode 9 having a gas permeable membrane 8 as shown in FIG.
When the sample is immersed in the test liquid 7, gaseous free iodine can pass through the gas permeable membrane 8 and reach the diaphragm type polarographic electrode 9. On the other hand, a cathode electrode 10 is installed on the electrode inner surface of the gas permeable membrane 8 so as to be in close contact with the membrane, and a supporting electrolyte 31 is formed within the gap between the membrane 8 and the cathode electrode 10 by capillary action. It is held in a thin film. Therefore, the free iodine that has passed through the gas permeable membrane 8 is
The thin supporting electrolyte layer is diffused to reach the cathode electrode 10. Furthermore, since an electrolytic voltage E [V] is applied from the outside between the cathode electrode 10 and the anode electrode 11, the electrolytic reaction of the above-mentioned formula (5) occurs on the cathode electrode surface, and the free This means that a current flows that is proportional to the amount of iodine. Further, the amount of free iodine that permeates through the gas permeable membrane is proportional to the free iodine concentration in the test liquid when the physical conditions are the same. Therefore, the cathode electrode 10
The amount of iodine that reaches and undergoes the electrolytic reaction of formula (5) is proportional to the free iodine concentration in the test liquid. That is, the current flowing through the external circuit is proportional to the free iodine concentration in the test liquid, and the residual chlorine concentration in the test liquid is ultimately determined.
又、本発明を実施するにあたつてヨウ化カリウ
ム溶液は、ヨウ化カリウム濃度が５×10-4〜５×
10-2mol／（とくに５×10-3mol／がのぞま
しい）となるように被検液に加えられる。その理
由を以下に説明する。もし被検液中にヨウ素イオ
ン（I-）が多量に存在する場合、遊離ヨウ素
（I2）はただちに下記に示す(6)式の反応によつてＩ
− ３なる錯体イオンを形成し、もはやヨウ素はガス
状態として存在していない為に気体透過膜を通過
しなくなり、従つて電解電流は発生し得なくな
る。 Further, in carrying out the present invention, the potassium iodide solution has a potassium iodide concentration of 5×10 -4 to 5×
It is added to the test solution at a concentration of 10 -2 mol/(especially preferably 5×10 -3 mol/). The reason for this will be explained below. If a large amount of iodine ions (I - ) are present in the test solution, free iodine (I 2 ) is immediately converted to I by the reaction of equation (6) shown below.
- 3 is formed, and since iodine no longer exists in a gaseous state, it no longer passes through the gas permeable membrane, and therefore no electrolytic current can be generated.
I2＋I-Ｉ− ３ ……(6)
そこで本発明者は研究、考察の結果、この(6)式
の反応が平衡反応であり、次の(7)式の如き平衡関
係に常にある事にまず着目した。 I 2 + I - I - 3 ...(6) Therefore, as a result of research and consideration, the present inventor has found that the reaction of equation (6) is an equilibrium reaction, and that there is always an equilibrium relationship as shown in equation (7) below. We first focused on
Ｋ＝〔Ｉ〓〕／〔Ｉ２〕〔Ｉ−〕＝7.1×10+2（25℃）
……(7)
ここで
〔Ｉ− ３〕：ヨウ素錯体イオン濃度
〔I2〕：遊離ヨウ素濃度
〔I-〕：ヨウ素イオン濃度
はじめに3.53×10-5mol／（これは残留塩素
が2.5（ppm〕の時に生ずるヨウ素濃度である。）
のヨウ素が存在した時ヨウ素イオンI-濃度が変る
につれ、ガス状の遊離ヨウ素I2がどの程度ヨウ素
錯体イオンＩ− ３に変化するかを前記第(7)式に基い
て計算したものが第３図である。この図からみれ
ばヨウ化カリウム濃度が10-4〜10-2mol／の間
で急激にI2（ガス状）からＩ− ３に変化し、
10-2mol／にあつては、Ｉ− ３が90％にも達し、I2
は残りの10％に過ぎない事になる。K=[I〓]/[ I2 ][I - ]=7.1×10 +2 (25℃)
...(7) Here, [I - 3 ]: Iodine complex ion concentration [I 2 ]: Free iodine concentration [I - ]: Iodine ion concentration Initially 3.53 × 10 -5 mol/(This means that the residual chlorine is 2.5 (ppm) ).This is the iodine concentration that occurs when
The amount of gaseous free iodine I2 that changes into iodine complex ion I - 3 as the iodine ion I - concentration changes when iodine is present is calculated based on equation (7) above. Figure 3. From this figure, when the potassium iodide concentration is between 10 -4 and 10 -2 mol/, it rapidly changes from I 2 (gaseous) to I - 3 .
At 10 -2 mol/, I - 3 reaches 90%, and I 2
is only the remaining 10%.
そこで、ヨウ素のうちかなりの部分がガス状態
として存在している様な適当なヨウ素イオン濃度
に被検液を調節すれば、本発明のヨウ素検出法に
よつて残留塩素を測定できる事となる。そこで、
適当なヨウ素イオン濃度を決めるに当つて注意す
べき点がある。それは、前記(1)〜(4)式によつて残
留塩素の濃度に応じて種々の濃度のヨウ素が発生
するのであるから、ヨウ素濃度によらず常に一定
の割合で遊離ヨウ素が存在する様なヨウ素イオン
濃度に設定しなければならない事である。もし、
その割合が変化したならば、本発明の遊離ヨウ素
検出法では、残留塩素濃度に比例した電解電流出
力が得られない事になる。そこで遊離ヨウ素の存
在割合、即ち〔Ｉ− ３〕／〔I2〕を一定にする為には
前記(7)式において〔I-〕を一定値に維持すれば良
い。即ち、前記(1)〜(4)、(6)式によつてヨウ素イオ
ンが残留塩素量に応じて消費され、結局ヨウ素イ
オン濃度は減少する訳であるが、始めに添加する
I-の量が残留塩素量に比べて圧倒的に多ければ、
その減少するヨウ素イオンの量は全体から見れば
微々たるものなので、ヨウ素イオン濃度は一定と
みなせる訳である。上水道の残留塩素測定に関し
ては、水道施行規則により3ppm程度までの残留
塩素が測定可能であれば良く、これから生じるヨ
ウ素濃度は4.2×10-5〔mol／〕程度であり、ヨ
ウ素イオンをヨウ素濃度の百から千倍程度添加し
ておけば、残留塩素との反応によるヨウ素濃度の
減少はほとんど無視できるようになる。従つて計
算上ではヨウ素イオン濃度を4.2×10-3〜4.2×
10-2〔mol／〕にすれば良い事になる。 Therefore, residual chlorine can be measured by the iodine detection method of the present invention by adjusting the test liquid to an appropriate iodine ion concentration such that a considerable portion of the iodine exists in the gaseous state. Therefore,
There are some points to keep in mind when determining an appropriate iodine ion concentration. This is because iodine is generated at various concentrations depending on the concentration of residual chlorine according to equations (1) to (4) above, so free iodine always exists at a constant rate regardless of the iodine concentration. It is necessary to set the iodine ion concentration. if,
If the ratio changes, the free iodine detection method of the present invention will not be able to obtain an electrolytic current output proportional to the residual chlorine concentration. Therefore, in order to keep the abundance ratio of free iodine, ie, [I − 3 ]/[I 2 ] constant, it is sufficient to maintain [I − ] at a constant value in the above equation (7). That is, according to equations (1) to (4) and (6) above, iodine ions are consumed according to the amount of residual chlorine, and the iodine ion concentration eventually decreases, but when added at the beginning,
If the amount of I - is overwhelmingly larger than the amount of residual chlorine,
The amount of iodine ions that decreases is insignificant compared to the whole, so the iodine ion concentration can be considered constant. Regarding the measurement of residual chlorine in water supplies, according to the Water Supply Enforcement Regulations, it is sufficient if residual chlorine can be measured up to about 3 ppm, and the iodine concentration generated from this is about 4.2 × 10 -5 [mol/]. By adding 100 to 1,000 times more iodine, the decrease in iodine concentration due to reaction with residual chlorine becomes almost negligible. Therefore, in calculation, the iodine ion concentration is 4.2×10 -3 ~4.2×
It would be good to set it to 10 -2 [mol/].
以上において理論的考察を行なつたが、次に実
験結果に基づいて説明を行う。第７図は35〔℃〕
において2.5〔ppm〕の残留塩素を含む被検液を
所定のPHに調整後、ヨウ化カリウム溶液を加えて
いつた時の隔膜式ポーラログラフ電極の出力電流
の変化を示したものである。ヨウ素イオン濃度が
10-4〔mol／〕迄は、残留塩素量に対して等量
以下であり、ヨウ素イオンは全て遊離ヨウ素に変
るために徐々に上昇する。（10-4〔mol／〕近
傍では、ヨウ素イオンが残留塩素に対して等量に
なり、残留塩素は全て反応し遊離ヨウ素となるた
めに最大値を取る。さらに10-4〔mol／〕以上
では、前述の如くヨウ素錯体イオンの生成に基づ
いて遊離ヨウ素が減少する事を示している。 Theoretical considerations have been made above, and next we will provide an explanation based on experimental results. Figure 7 is 35 [℃]
This figure shows the change in the output current of the diaphragm polarographic electrode when a potassium iodide solution was added to the test solution containing 2.5 [ppm] of residual chlorine after adjusting it to the specified pH. Iodine ion concentration
Up to 10 -4 [mol/] is less than the equivalent amount to the amount of residual chlorine, and it gradually increases because all iodine ions are converted to free iodine. (At around 10 -4 [mol/], the amount of iodine ions becomes equal to the residual chlorine, and all the residual chlorine reacts and becomes free iodine, so the maximum value is reached. Furthermore, at 10 -4 [mol/] or more This shows that free iodine decreases due to the formation of iodine complex ions, as described above.
理論に基づいた第３図とは若干異なる事が分か
り、10-4〜10-1〔mol／〕の広いヨウ素イオン
濃度範囲で遊離ヨウ素からヨウ素錯体イオンに変
化している事がわかる。そこで、10-3〔mol／
〕のヨウ素イオン濃度において、残留塩素の検
量線を取つたものが第８図であり、充分な直線性
が得られる事が判明した。この直線性は通常の被
検液温度である20〜35〔℃〕の温度範囲で成立し
ている。 It can be seen that there is a slight difference from Figure 3, which is based on theory, and that free iodine changes to iodine complex ions over a wide iodine ion concentration range of 10 -4 to 10 -1 [mol/]. Therefore, 10 -3 [mol/
Figure 8 shows the calibration curve of residual chlorine at the iodine ion concentration of 20%, and it was found that sufficient linearity could be obtained. This linearity is established in the temperature range of 20 to 35 [°C], which is the normal temperature of the test liquid.
なお、前記ヨウ素イオン濃度は、実用上５×
10-4〜５×10-2〔mol／〕の範囲でも充分可能
である。 Note that the iodine ion concentration is practically 5×
A range of 10 -4 to 5×10 -2 [mol/] is also sufficient.
次に、電解槽内の支持電解液としては、一般に
隔膜式のポーラログラフ電極で用いられている塩
化カリウムのようなイオン性物質が好ましいと考
えられるが、種々研究の結果、ヨウ素イオンを主
成分とする水溶液たとえばヨウ化カリウム水溶液
が好ましい事がわかつた。本発明者の研究によれ
ば、たとえば0.1mol／塩化カリウム溶液を用い
た場合、残留塩素が高濃度になるにつれて第４図
中のａに示す様な非直線性を示すのである。一
方、たとえば0.1mol／ヨウ化カリウム溶液を用
いると、同図中のｂのような直線に改良され、ヨ
ウ素イオンの存在が必要であることが判明した。 Next, as the supporting electrolyte in the electrolytic cell, it is thought that an ionic substance such as potassium chloride, which is generally used in diaphragm-type polarographic electrodes, is preferable, but as a result of various studies, it has been found that iodine ions are the main component. It has been found that an aqueous solution, such as an aqueous potassium iodide solution, is preferable. According to the research conducted by the present inventors, for example, when a 0.1 mol/potassium chloride solution is used, as the concentration of residual chlorine increases, nonlinearity as shown in a in FIG. 4 is exhibited. On the other hand, when a 0.1 mol/potassium iodide solution was used, for example, the line was improved to a straight line as shown in b in the figure, indicating that the presence of iodine ions was required.
次に本発明の一実施例を第５図に示す。同図に
おいて、１２はヨウ化カリウム溶液（0.03mol／
）のタンク、１３は試薬ポンプ、１４は校正用
標準濃度液（この実施例ではヨウ素酸カリウム溶
液、3.03ppm）のタンク、１５は被検液導入口、
１６は電磁弁、１７は被検液ポンプ、１８は一定
温度にするための熱交換器、１９は隔膜式ポーラ
ログラフ電極を有する検出部、２０は該検出部１
９よりの信号を処理する電気回路、２１は該電気
回路２０よりの信号を記録する記録計、２２は電
磁弁１６により校正用標準液と被検液を切換える
ための制御装置である。そして、前記検出部１９
を第６図に示す。同図において、２４は被検液導
入口（なお導出口は図において導入口の真後にあ
る。）、２５はマグネチツクスターラー２６により
駆動されて被検液を撹拌する撹拌翼、２３は隔膜
式ポーラログラフ電極、２７は、ガス透過膜（た
とえば多孔質テフロン膜よりなり、市販品として
は住友電工製のフロロポアがあげられる。）であ
つて、その外面２７１のみが被検液と接する。２
８，２９は前記透過膜２７の内面２７２側に設け
られたカソード電極及びアノード電極であつて、
電解槽３０内の支持電解液３１中に浸漬されてい
る。前記透過膜内面２７２とカソード電極２８と
は密接状態で設けられており、その間隙（数ミク
ロン程度）内には毛管現象により支持電解液３１
が薄膜状に保持される。 Next, one embodiment of the present invention is shown in FIG. In the same figure, 12 is a potassium iodide solution (0.03mol/
) tank, 13 is a reagent pump, 14 is a tank for calibration standard concentration solution (in this example, potassium iodate solution, 3.03 ppm), 15 is a test liquid inlet,
16 is a solenoid valve, 17 is a sample liquid pump, 18 is a heat exchanger for maintaining a constant temperature, 19 is a detection unit having a diaphragm type polarographic electrode, and 20 is the detection unit 1
9 is an electric circuit for processing the signal from the electric circuit 20; 21 is a recorder for recording the signal from the electric circuit 20; and 22 is a control device for switching between the calibration standard solution and the test solution using the electromagnetic valve 16. Then, the detection section 19
is shown in Figure 6. In the figure, 24 is a sample liquid inlet (the outlet is located directly behind the sample inlet), 25 is a stirring blade that is driven by a magnetic stirrer 26 to stir the sample liquid, and 23 is a diaphragm type. The polarographic electrode 27 is a gas permeable membrane (for example, made of a porous Teflon membrane; a commercially available product is Fluoropore manufactured by Sumitomo Electric Industries, Ltd.), and only its outer surface 271 is in contact with the sample liquid. 2
8 and 29 are a cathode electrode and an anode electrode provided on the inner surface 272 side of the permeable membrane 27,
It is immersed in a supporting electrolyte 31 in an electrolytic cell 30. The inner surface 272 of the permeable membrane and the cathode electrode 28 are provided in close contact with each other, and the supporting electrolyte 31 flows into the gap (about several microns) due to capillary action.
is retained in the form of a thin film.
尚、前記カソード電極２８は白金によりデイス
ク状に、アノード電極２９は白金によりラセン状
にそれぞれ形成されており、又、アノード電極２
９は、カソード電極２８の20倍以上の表面積を有
するようにしてある。 The cathode electrode 28 is formed of platinum in a disk shape, and the anode electrode 29 is formed of platinum in a spiral shape.
9 has a surface area 20 times or more that of the cathode electrode 28.
本発明では、従来の回転白金電極によるポーラ
ログラフ法の持つ欠点を全て解消し、長時間にわ
たつて極めて安定に残留塩素濃度を測定し得るよ
うになつた。 The present invention eliminates all the drawbacks of the conventional polarographic method using a rotating platinum electrode, and makes it possible to measure the residual chlorine concentration extremely stably over a long period of time.
即ち、
残留塩素検出部のカソード電極を回転させる
必要がない。 That is, there is no need to rotate the cathode electrode of the residual chlorine detection section.
残留塩素検出部の構造が非常に簡単である。 The structure of the residual chlorine detection section is very simple.
残留塩素検出部の電解電極は、ガス透過膜に
よつて隔離されているので、被検液と接するこ
とがなく、水溶性の妨害物質の影響を一切受け
る事がない。 Since the electrolytic electrode of the residual chlorine detection section is isolated by a gas permeable membrane, it does not come into contact with the test liquid and is not affected by water-soluble interfering substances.
電極の被検液によつて汚染されることがなく
従つて、複雑な洗浄機構が不要となる。 The electrode is not contaminated by the test liquid, and therefore a complicated cleaning mechanism is not required.
測定装置全体が非常にコンパクトになつたた
め、応答が速く、（実験によれば、従来の回転
白金電極によるポーラログラフ法では数分を要
したのに対し、本発明方法では１分以内であつ
た。）被検液の流量や試薬の消費が従来の約1/5
〜1/10に減少した。 Because the entire measuring device has become very compact, the response is fast (according to experiments, the time required by the method of the present invention was within one minute, whereas the conventional polarographic method using a rotating platinum electrode required several minutes). ) Test solution flow rate and reagent consumption are approximately 1/5th compared to conventional methods.
It decreased to ~1/10.
第１図は従来方法を示す説明図、第２図は本発
明の原理を説明する図、第３図はヨウ化カリウム
濃度と遊離ヨウ素の反応率との関係を示すグラ
フ、第４図は残留塩素濃度と電解電流との関係を
示すグラフ、第５図は本発明の一実施例を示すフ
ローチヤート、第６図は検出部の縦断面図、第７
図は実験結果を示すグラフ、第８図は残留塩素の
検量線を示す図である。
７……被検液、８，２７……ガス透過膜、９，
２３……隔膜式ポーラログラフ電極、１０，２８
……カソード電極、１１，２９……アノード電
極、１９……検出部、３１……支持電解液。
Figure 1 is an explanatory diagram showing the conventional method, Figure 2 is a diagram explaining the principle of the present invention, Figure 3 is a graph showing the relationship between the potassium iodide concentration and the reaction rate of free iodine, and Figure 4 is a graph showing the residual A graph showing the relationship between chlorine concentration and electrolytic current, FIG. 5 is a flowchart showing an embodiment of the present invention, FIG. 6 is a longitudinal cross-sectional view of the detection section, and FIG.
The figure is a graph showing the experimental results, and FIG. 8 is a diagram showing the calibration curve of residual chlorine. 7... Test liquid, 8, 27... Gas permeable membrane, 9,
23...Diaphragm type polarographic electrode, 10,28
... Cathode electrode, 11, 29 ... Anode electrode, 19 ... Detection section, 31 ... Supporting electrolyte.
Claims (1)
節し、さらに、適当量のヨウ化カリウム溶液を加
えて被検液中の残留塩素に対して一定比率の遊離
ヨウ素を生ぜしめ、この遊離ヨウ素を、ガス透過
膜を用いた隔膜式ポーラログラフ電極にて検出し
該電極の電流出力でもつて被検液中の残留塩素を
測定する残留塩素測定方法。 ２ 隔膜式ポーラログラフ電極の支持電解液とし
てヨウ素イオンを主成分とする溶液を用いること
を特徴とする特許請求の範囲第１項に記載の残留
塩素測定方法。 ３ 被検液のヨウ化カリウム濃度が５×10-4〜５
×10-2mol／となるように、ヨウ化カリウム溶
液を被検液に加えることを特徴とする特許請求の
範囲第１項又は第２項に記載の残留塩素測定方
法。[Claims] 1. Add a buffer or acid to the test solution to adjust the pH to a predetermined value, and then add an appropriate amount of potassium iodide solution to adjust the pH at a certain ratio to the residual chlorine in the test solution. A method for measuring residual chlorine in which free iodine is generated, the free iodine is detected with a diaphragm-type polarographic electrode using a gas-permeable membrane, and residual chlorine in a test liquid is measured by the current output of the electrode. 2. The method for measuring residual chlorine according to claim 1, characterized in that a solution containing iodine ions as a main component is used as the supporting electrolyte of the diaphragm type polarographic electrode. 3 Potassium iodide concentration of the test solution is 5 × 10 -4 ~ 5
The method for measuring residual chlorine according to claim 1 or 2, characterized in that a potassium iodide solution is added to the test liquid so that the residual chlorine concentration is x10 -2 mol/.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16193278A JPS5587942A (en) | 1978-12-26 | 1978-12-26 | Measuring rdevice of residual chlorine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16193278A JPS5587942A (en) | 1978-12-26 | 1978-12-26 | Measuring rdevice of residual chlorine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5587942A JPS5587942A (en) | 1980-07-03 |
| JPS623898B2 true JPS623898B2 (en) | 1987-01-27 |
Family
ID=15744769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16193278A Granted JPS5587942A (en) | 1978-12-26 | 1978-12-26 | Measuring rdevice of residual chlorine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5587942A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59191669U (en) * | 1983-06-06 | 1984-12-19 | 電気化学計器株式会社 | Residual chlorine measuring device |
| JP3748388B2 (en) * | 2001-04-11 | 2006-02-22 | 弘隆 小宮 | Acid gas detector |
-
1978
- 1978-12-26 JP JP16193278A patent/JPS5587942A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5587942A (en) | 1980-07-03 |
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