JPH0452407B2 - - Google Patents

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Publication number
JPH0452407B2
JPH0452407B2 JP58027723A JP2772383A JPH0452407B2 JP H0452407 B2 JPH0452407 B2 JP H0452407B2 JP 58027723 A JP58027723 A JP 58027723A JP 2772383 A JP2772383 A JP 2772383A JP H0452407 B2 JPH0452407 B2 JP H0452407B2
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JP
Japan
Prior art keywords
electrode
hydrogen ion
ion concentration
silver
measuring device
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 - Lifetime
Application number
JP58027723A
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Japanese (ja)
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JPS59154351A (en
Inventor
Makoto Noda
Toshio Akyama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NGK Insulators Ltd
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NGK Insulators Ltd
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Filing date
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Priority to JP2772383A priority Critical patent/JPS59154351A/en
Publication of JPS59154351A publication Critical patent/JPS59154351A/en
Publication of JPH0452407B2 publication Critical patent/JPH0452407B2/ja
Granted legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403Cells and electrode assemblies
    • G01N27/4035Combination of a single ion-sensing electrode and a single reference electrode

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

産業上の利用分野 本発明は、水溶液中の水素イオン濃度を測定す
る装置に関するものである。 更に詳しくは、高温度、高圧力条件下の水溶液
のPH値を測定する装置に関するものであつて、 水溶液中の水素イオン濃度測定用センサー、 各種工業用水の水質管理用のPH測定用及び 高温、高圧力条件下での直接測定用の水素イオン
濃度測定装置を提供するにある。 (従来の技術) 従来水溶液中の水素イオン濃度を測定するには
測定液中に指示電極として水素イオン選択性電極
と、比較電極を挿入して測定される。第1図には
従来の測定装置の概略を示す。 1は指示電極で水素イオンの選択性電極が用い
られる。2は比較電極で、内部に内部電極3と内
部電解質4を収納し、液絡部5を有している。6
は電位差計である。7は測定液である。 従来、水素イオン選択性電極としてはガラス電
極が用いられている。 ガラス電極の構造は周知の如く、水素イオン濃
度に感応するガラス感応膜を有し、内部に既知の
水素イオン濃度を有す電解質内部溶液を充填し、
この内部電解質溶液と接する内部電極をもち、前
記ガラス膜の内、外面間には、外部の測定液中の
水素イオン活量濃度に応じて、ネルンストの式に
従う電位差を発生する。 このようなガラス電極は、その特性を良く発揮
させるため、ガラスの水素イオン感応膜を極めて
薄く、均質にかつ膜内部に欠陥や歪が生じないよ
う製作されている。 このガラス感応膜は、水溶液の液性状によつて
は浸蝕されたりして、感応膜としての電池出力が
低下する等の劣化を起してしまう欠点がある。 また、特に測定液が高温度条件では、ガラス膜
の劣化は更に促進され、かつ熱的衝撃にも耐え難
く実質的には、これの用いられる液温度は最大
110〜130℃である。 一方、比較電極2としては、一般にカロメル電
極或いは銀−塩化銀電極等が用いられている。 例えば銀−塩化銀電極は周知の如く、ガラス等
で作られた容器2a内に電解質塩溶液4を満し、
その中に塩化銀を被覆した銀よりなる内部電極3
を浸漬し、電気化学的半電池を形成し、かつ容器
2aの一部に所謂液絡部5をもつている。 この液絡部5を介して被測定液7と比較電極2
の内部電解質4とは、イオンの拡散、伝導が達成
されている。 (発明が解決しようとする課題) 以上の技術構成故に実際の測定に際しては次の
ような欠点を本質的に有している。 1 液絡部5を介して内部電解質4のイオンが測
定液中に漏出する。このため被測定液7が汚染
されたり、真のイオン濃度を測定することがで
きない場合が生ずる。 2 液絡部5よりの漏出により内部電解質液4が
減少したり濃度の変化が起つたりして、比較電
極としての本来の基準電位が変動してしまうこ
とがある。 3 又液絡部5が閉塞したりすることも発生し、
この場合には前述の電気導通が得られなくな
り、測定を困難にしてしまう。 4 液絡部5での円滑な電気伝導を得るには、内
部液4は少なくとも被測定液7よりも正圧条件
であることが必要である。 以上のような欠点に対して、極力漏出を少くす
るような工夫として液絡部の構造を微細化した
り、電解質をゲル状化したりして内部電解質の変
質や減耗を防止したり、内部液に加圧を行う装置
を配置したりという各種方法が用いられている。
しかしながら内部に比較電極としての電位を安定
させるため電解質を有し液絡部が形成されている
従来の技術では上記欠点を払拭できるものではな
い。以上説明した通り従来の測定方法、技術にお
いては測定液が原子力発電所での炉水の1次冷却
水や、ボイラー水や化学プラント等でみられる高
温高圧条件下の場合、ここで用いることのできる
比較電極は特に液絡部でのトラブルが発生し、満
足されるものがないばかりか、PHの測定自体が極
めて困難なものである。 最近この技術に対して酸素イオン伝導性隔膜を
用いた新規な水素イオン濃度センサーが提案され
ている。 米国特許第4264424号明細書(特開昭56−77751
号公報)によれば、ガラス膜の代りに、特殊セラ
ミツクよりなる隔膜を用い、この隔膜の両面間に
発生する電位差を測定する方法が示されている
が、この特殊セラミツクの内部抵抗が極めて大き
いことに起因して、発生電位差が不安定であつて
測定の信頼性を欠くものの他、この測定を行うに
は、比較電極としてやはり従来の技術の液絡構造
をもつ電極が使用されている。このため、上述し
た如くの欠点が依然残つている。 本発明の目的は上述した従来の水素イオン濃度
測定技術のもつ欠点を克服する新規な水素イオン
濃度測定装置を提供するものである。 第1の目的は高温度の測定液を直接測定でき
る。 第2の目的は高圧力の測定液を直接測定でき
る。 第3の目的は比較電極として内部電解質をもた
ない。 第4の目的は所謂液絡構造をもたない。 第5の目的は極めてシンプルに設計でき、その
取扱いが簡便容易となる。 (課題を解決するための手段) 本発明は、測定装置の一方の電極端子に接続さ
れる端子をもつ水素イオン濃度測定用指示電極
と、他方の電極端子に接続される端子をもつた金
属電極体とを水溶液中に直接浸漬して両端子間に
発生する電位差を上記測定装置で測定することに
より水溶液中の水素イオン濃度を測定する装置に
おいて、水素イオン濃度測定用指示電極は一端開
放で他端に閉塞端を備えた容器とその内部に内部
電極と内部電解質とを有し、その閉塞端は少なく
とも酸素イオン伝導性固体電解質から形成され、
かつ、他方の金属電極体の上記水溶液に接触する
表面は銀、銀合金又は銀、銀合金の酸化物より選
択された何れかが被覆されていることを特徴とす
る水素イオン濃度測定装置である。 本発明に使用する酸素イオン伝導性固体電解質
は安定化ジルコニアが好ましい。 この安定化ジルコニアは本発明の実施例では約
150℃より動作する。この動作温度は安定化ジル
コニアの純度を増す等の手段により更に低温化で
きる。 一般的な安定化ジルコニアの動作温度は600℃
程度と高温であるが水素イオン濃度計としてはよ
り低温で動作する。これは、水素イオン濃度計と
して水溶液に使用する場合水溶液中の反応におけ
る H2OH++OH- ……(1) OH-H++O-- ……(2) (2)式のO--イオン量を直接測定しているのに対
し、一般的な気体中では安定化ジルコニアに設置
した触媒によりO2+4e-→2O--として一旦O--
イオン化させる必要があり、このエネルギー差に
より両者の相違が生じているものと発明者は推定
している。 金属電極体は銀、銀合金あるいは銀、銀合金に
その酸化物を被覆したもの又はアルミ、ニツケ
ル、銅、鉄等の金属地金の上に銀、銀合金を鍍金
或いは積層して被覆したもの或いは更にその外側
に銀、銀合金の酸化物を被着したものでもよい。 また金属電極体は液浸漬部の一部が少くとも絶
縁体で被覆されているもので、その基部が絶縁体
に取付けられ測定装置への取付部材となるもので
あればよい。 本発明の構成を更に詳しく説明する。 第2図には、高温度・高圧力条件下で測定で
き、かつ測定液中にイオン性電解質を漏出させな
い本発明の構成を示す。第2図において10は指
示電極で、20は金属電極体で両者は測定液15
に浸漬(接触)している。 この指示電極10は固体電解質でつくられた水
素イオン感応膜10Aをもつ一端閉塞とした中空
体構造をもつている。この固体電解質としては安
定化ジルコニアが好ましい。 この中空体の内側には、内部電極11と内部電
解質12が充填されている。 内部電極11は、塩化銀を被覆した銀が多くの
場合用いられているが他の金属を使用してもよ
い。 内部電解質12は、例えば塩化カリウム溶液等
の塩溶液が用いられる。又金属とその金属酸化物
との混合体でつくられた固体電解質も用いられ
る。 このように構成された指示電極10は、電気信
号取出し用の端子13をもつている。この端子1
3は内部電極11と電気的に接続されている。 又この中空体の開口端は接着等の手段で内部と
外部とが遮断、密封されることが望ましい。 金属電極体20は、銀あるいは銀合金又は、銀
及び銀合金の酸化物が表面に被覆された金属より
選ばれる。 この金属電極体20は、その表面の一部(又は
全部)が露出しており、かつ絶縁被覆部21と絶
縁部22をもつている。 絶縁部22は測定用容器16に取付けられるよ
うな取付部材を構成することもある。更に電気信
号取出し用端子23をもち、この端子23は金属
電極体20と電気導通している。 指示電極10と金属電極体20との間に発生す
る電位差は一方の端子13と他方の端子23に接
続された増巾器25を介して電圧計26で測定さ
れる。指示電極10は大きな内部抵抗をもつてい
るので、増巾器25は高入力抵抗をもち、電磁気
的なノイズの進入防止のため夫々の端子13,2
3からのリード線はシールド14,24を施して
ある。 指示電極10を構成する中空体を安定化ジルコ
ニア磁器でつくり、内部電解質12は塩化カリウ
ム溶液で、内部電極11は塩化銀(AgCl)を被
覆した銀でつくり、金属電極体20として銀を用
いて構成した本発明の指示電極10と金属電極体
20を測定液である水溶液中に浸漬したときの動
作機構を次に示す。 内部電解質12と接した内部電極11には電気
化学的単極電位が発生する。 指示電極10の感応膜部10Aの内、外面で
は、夫々の膜界面で電気化学的ポテンシヤルが発
生する。この発生ポテンシヤルは、夫々の界面で
のイオン種の平衡によつて規定される。 膜10A内面上の電位は、内部の電解質の水素
イオン濃度を定めると一定となる。 膜10A外面上の電位は、測定液15中のイオ
ン種の活量濃度がこの膜面上で平衡しているので
今イオン種を水素イオンに注目してみると、ここ
で平衡した水素イオンの活量濃度に依存したネル
ンストの式に従う電位が発生する。一般に、希薄
水溶液中の水素イオンの活量濃度は水素イオン濃
度に比例するので結局、この感応膜10A内外面
間には、測定液中の水素イオン濃度の対数に比例
したネルンストの式に従う電位差が発生する。又
この感応膜10Aの近くにおいた金属電極20の
表面でも水溶液中のイオン種の活量に相応した半
電池が構成され、この電極20には単極電位が発
生する。従つて、このように構成された装置は全
体として一つの電池として見ることができる。 この場合金属電極体20がつくる単極電位が測
定液中の水素イオンの濃度の影響を受けなけれ
ば、本発明の装置で測定された電位差は測定液中
の水素イオン濃度の対数に比例するものである。 本発明は、水溶液中の水素イオン濃度の影響を
受けにくく、しかも安定した電位を発生する金属
電極体を開発した。この場合の金属電極体として
は銀、銀合金又は銀及び銀合金の酸化物を表面に
被覆した金属または銅、アルミニウム、ニツケ
ル、鉄等の金属地金に銀又は銀合金を鍍金、被
覆、した金属体が上げられる。なお、比較電極と
して有効なものには銀、銀と銅の合金、銀とニツ
ケルの合金、銀の酸化物、銀と銅の酸化物がよ
く、これらの代表として銀及び銀と銅の合金が好
ましいのである。 以上述べた本発明よりなる指示電極と金属電極
体に、適切な取付具を装着して使用すると、本発
明の測定装置は従来技術に対し 比較電極のもつ内部電解質を測定液中に漏出
しない。 液絡構造をもたない。 接液体が物性的に安定な固体でできている。 というまつたく新規な水素イオン濃度測定装置を
提供することができる。 なお、第3図図中における符号のうち、第2図
と同一符号は同一又は類似する構成要素を示す。 (実施例) 本発明の具体的実施例について、以下に説明す
る。 実施例 1 第2図に示した本発明の構成において10は指
示電極で、8.5モルのイツトリアをドープして安
定化ジルコニアでその一端が閉塞し他端が開放し
た構造をしている筒状のセラミツクである。外径
8mmφ、内径6mmφ、長さ150mmで閉塞端部の肉
厚は4.5mmである。 20は金属電極体であり、太さ1mmφの銀線
で、約20mmが露出しその他はセラミツクコーテン
グされている。 指示電極10の内部には、内部電解質12と内
部電極11が収納されている。 内部電解質12は3モル/のKCl水溶液で、
内部電極11は、AgClを被覆した太さ1mmφの
銀線である。 第3図には、本発明の測定装置の性能を確認す
るための実験装置の構成を示す。第3図において
試験槽30はSUSでつくられ内容積が約1.8で、
測定液15として純水が約1.3入つている。こ
の試験槽30には、指示電極10と金属電極体2
0を測定液15に浸漬(接触)するよう適切な取
付具によつて装着し、両電極10,20の電極端
子は夫々テフロン被覆の同軸ケーブルにより高入
力抵抗をもつ増巾器25に接続され、増巾器25
の出力をペン書記録計によつて測定した。指示電
極10は一般に高い内部抵抗をもつため増巾器2
5は高入力抵抗回路をもつており、指示電極10
と増巾器25を接続するリード線にはシールド3
7が施してある。又金属電極体20と増巾器25
とを接続するリード線も、電磁気的誘導雑音筒の
侵入防止の目的でシールド24が施してある。薬
液槽40,41,42は測定液の水溶液中のイオ
ン濃度を変化させるため例えば、薬液槽40には
酸性水溶液、薬液槽41には中性液、薬液槽42
にはアルカリ性水溶液という所定の薬液が入つて
おり、39は切換分岐部、38は薬液導入部で、
切換分岐部39を操作することによつて任意の薬
液を測定液中に導入させることができる。更に高
温度条件下や高圧力条件下での測定を行うため次
の機能、装置を有している。43は加熱部、44
は温度計、45は加熱装置よりなり測定液を加
温、温度コントロールさせ、かつ薬液導入部38
には、加圧送液できる加圧装置47が配置され、
試験槽30の内圧力を検出する圧力計46が取付
けられている。 試験槽30は、加圧容器を構成しているので、
これに取付けられる部材(指示電極10、金属電
極体20、圧力計46、温度計44並びに薬液導
入部38)は、その取付界面でこれらの圧力に十
分耐えるようなシール機能をもつて強固に装着さ
れている。 実験は、薬液槽40,41,42タンクの酸液
又はアルカリ液を適量測定液に流入させ測定液の
PH値を変化させたときの両電極間の発生電位差を
測定記録した結果を第4図に示した。 ここにおいて、水温は95℃にコントロールし
た。この時の電位差は+95mVを示した。 次に酸溶液をこの測定液に添加し、測定液のPH
値が2.4となつたとき、両電極間の発生電位差は
+340mVを示し、更にアルカリ溶液を添加して
測定液のPH値が11.8となつたときの電位差は−
163mVを示し、再度酸溶液を添加して測定液の
PH値が2.3となつたときの電位差は+344mVを示
した。また、測定液のPH変化に対して短時間で飽
和値に達し安定した電位差が得られた。 実施例 2 実施例1で説明した構成において、金属電極体
として1mmφの銀:銅=9:1の銀合金を用い
て、上記と同様な構成の測定システムを組立てて
測定液のPH値を変化させたときの両電極間に発生
する電位差を測定した。その結果を第1表に示
す。
INDUSTRIAL APPLICATION FIELD The present invention relates to an apparatus for measuring hydrogen ion concentration in an aqueous solution. More specifically, it relates to a device for measuring the PH value of an aqueous solution under high temperature and high pressure conditions, such as a sensor for measuring hydrogen ion concentration in an aqueous solution, a sensor for measuring PH value for water quality control of various industrial waters, and a high temperature, The present invention provides a hydrogen ion concentration measuring device for direct measurement under high pressure conditions. (Prior Art) Conventionally, the hydrogen ion concentration in an aqueous solution is measured by inserting a hydrogen ion selective electrode as an indicator electrode and a comparison electrode into the measurement liquid. FIG. 1 shows an outline of a conventional measuring device. Reference numeral 1 denotes an indicator electrode, which is a hydrogen ion selective electrode. A reference electrode 2 houses an internal electrode 3 and an internal electrolyte 4, and has a liquid junction 5. 6
is a potentiometer. 7 is a measurement liquid. Conventionally, a glass electrode has been used as a hydrogen ion selective electrode. As is well known, the structure of the glass electrode has a glass sensitive membrane that is sensitive to hydrogen ion concentration, and is filled with an electrolyte internal solution having a known hydrogen ion concentration.
It has an internal electrode in contact with this internal electrolyte solution, and generates a potential difference between the inner and outer surfaces of the glass membrane according to the Nernst equation depending on the hydrogen ion activity concentration in the external measurement liquid. In order to make good use of the characteristics of such a glass electrode, the glass hydrogen ion sensitive membrane is manufactured to be extremely thin and homogeneous, and without any defects or distortions inside the membrane. This glass sensitive membrane has the disadvantage that it may be eroded depending on the liquid properties of the aqueous solution, resulting in deterioration such as a decrease in the battery output as a sensitive membrane. In addition, especially when the temperature of the measurement liquid is high, the deterioration of the glass membrane is further accelerated and it is difficult to withstand thermal shock.
The temperature is 110-130℃. On the other hand, as the comparison electrode 2, a calomel electrode, a silver-silver chloride electrode, or the like is generally used. For example, as is well known, the silver-silver chloride electrode is made by filling a container 2a made of glass or the like with an electrolyte salt solution 4,
Internal electrode 3 made of silver coated with silver chloride
is immersed to form an electrochemical half cell, and has a so-called liquid junction 5 in a part of the container 2a. The liquid to be measured 7 and the reference electrode 2 are connected to each other via this liquid junction 5.
The internal electrolyte 4 achieves ion diffusion and conduction. (Problems to be Solved by the Invention) Due to the above-mentioned technical configuration, there are essentially the following drawbacks in actual measurement. 1 Ions of the internal electrolyte 4 leak into the measurement liquid via the liquid junction 5. For this reason, the liquid to be measured 7 may be contaminated or the true ion concentration may not be measured. 2. The internal electrolyte 4 may decrease or its concentration may change due to leakage from the liquid junction 5, which may cause the original reference potential of the reference electrode to fluctuate. 3. Also, the liquid junction 5 may become clogged,
In this case, the electrical continuity described above cannot be obtained, making measurement difficult. 4. In order to obtain smooth electrical conduction at the liquid junction 5, it is necessary that the internal liquid 4 is at least under a more positive pressure condition than the liquid to be measured 7. To address the above-mentioned drawbacks, we have tried to reduce leakage as much as possible by making the structure of the liquid junction finer, making the electrolyte gel-like, and preventing deterioration and depletion of the internal electrolyte. Various methods are used, such as arranging a device that applies pressure.
However, the above-mentioned drawbacks cannot be eliminated with the conventional technology in which a liquid junction is formed with an electrolyte in order to stabilize the potential as a comparison electrode. As explained above, in conventional measurement methods and techniques, when the measuring liquid is under high temperature and high pressure conditions such as primary cooling water of reactor water in nuclear power plants, boiler water, and chemical plants, it is difficult to use it here. The reference electrodes that can be used are not only unsatisfactory due to problems especially at the liquid junction, but also make the PH measurement itself extremely difficult. Recently, a new hydrogen ion concentration sensor using an oxygen ion conductive diaphragm has been proposed for this technology. U.S. Patent No. 4264424 (Japanese Unexamined Patent Publication No. 56-77751
According to the publication, a method is proposed in which a diaphragm made of a special ceramic is used instead of a glass membrane and the potential difference generated between the two sides of the diaphragm is measured, but the internal resistance of this special ceramic is extremely large. Due to this, the generated potential difference is unstable and the measurement is unreliable, and in order to carry out this measurement, a conventional electrode having a liquid junction structure is also used as a reference electrode. Therefore, the above-mentioned drawbacks still remain. An object of the present invention is to provide a new hydrogen ion concentration measuring device that overcomes the drawbacks of the conventional hydrogen ion concentration measuring techniques described above. The first purpose is to be able to directly measure high-temperature measurement liquids. The second purpose is to be able to directly measure high-pressure measurement liquids. The third purpose is to have no internal electrolyte as a reference electrode. The fourth purpose is not to have a so-called liquid junction structure. The fifth purpose is that it can be designed extremely simply and its handling is simple and easy. (Means for Solving the Problems) The present invention provides an indicator electrode for hydrogen ion concentration measurement having a terminal connected to one electrode terminal of a measuring device, and a metal electrode having a terminal connected to the other electrode terminal. In a device that measures hydrogen ion concentration in an aqueous solution by directly immersing the body in an aqueous solution and measuring the potential difference generated between both terminals with the above measuring device, the indicator electrode for hydrogen ion concentration measurement is open at one end and the other is open. A container having a closed end and an internal electrode and an internal electrolyte inside the container, the closed end being formed of at least an oxygen ion conductive solid electrolyte,
and a hydrogen ion concentration measuring device characterized in that the surface of the other metal electrode body that comes into contact with the aqueous solution is coated with one selected from silver, a silver alloy, or an oxide of silver or a silver alloy. . The oxygen ion conductive solid electrolyte used in the present invention is preferably stabilized zirconia. This stabilized zirconia is approximately
Operates from 150℃. This operating temperature can be further lowered by means such as increasing the purity of the stabilized zirconia. Typical stabilized zirconia operating temperature is 600℃
However, as a hydrogen ion concentration meter, it operates at a lower temperature. When used as a hydrogen ion concentration meter in an aqueous solution, H 2 OH + +OH - ......(1) OH - H + +O -- ......(2) O -- ion in formula (2) While the amount is directly measured, in a general gas, it is necessary to ionize O 2 +4e - →2O -- into O -- using a catalyst installed in stabilized zirconia, and this energy difference causes the two to ionize. The inventor estimates that there is a difference between the two. Metal electrode bodies are silver, silver alloys, silver or silver alloys coated with their oxides, or metal base metals such as aluminum, nickel, copper, iron, etc., coated with silver or silver alloys by plating or lamination. Alternatively, an oxide of silver or a silver alloy may be coated on the outside thereof. Further, the metal electrode body may be one in which at least a part of the liquid immersion part is covered with an insulator, and the base thereof is attached to the insulator and serves as a mounting member for the measuring device. The configuration of the present invention will be explained in more detail. FIG. 2 shows a configuration of the present invention that allows measurement under high temperature and high pressure conditions and prevents ionic electrolyte from leaking into the measurement liquid. In Fig. 2, 10 is an indicator electrode, 20 is a metal electrode body, and both are the measuring liquid 15.
immersed in (contact with) This indicator electrode 10 has a hollow body structure with one end closed and has a hydrogen ion sensitive membrane 10A made of a solid electrolyte. Stabilized zirconia is preferred as this solid electrolyte. The inside of this hollow body is filled with an internal electrode 11 and an internal electrolyte 12. The internal electrodes 11 are often made of silver coated with silver chloride, but other metals may also be used. For the internal electrolyte 12, a salt solution such as a potassium chloride solution is used, for example. Solid electrolytes made of mixtures of metals and metal oxides are also used. The indicator electrode 10 configured in this manner has a terminal 13 for taking out an electric signal. This terminal 1
3 is electrically connected to the internal electrode 11. Further, it is desirable that the open end of this hollow body is sealed and sealed between the inside and the outside by adhesive or other means. The metal electrode body 20 is selected from silver, a silver alloy, or a metal whose surface is coated with an oxide of silver and a silver alloy. This metal electrode body 20 has a part (or all) of its surface exposed, and has an insulating coating part 21 and an insulating part 22. The insulating portion 22 may also constitute a mounting member that can be attached to the measurement container 16. Furthermore, it has a terminal 23 for taking out an electric signal, and this terminal 23 is electrically connected to the metal electrode body 20. The potential difference generated between the indicator electrode 10 and the metal electrode body 20 is measured by a voltmeter 26 via an amplifier 25 connected to one terminal 13 and the other terminal 23. Since the indicator electrode 10 has a large internal resistance, the amplifier 25 has a high input resistance and is connected to the terminals 13 and 2 to prevent electromagnetic noise from entering.
The lead wires from 3 are shielded 14, 24. The hollow body constituting the indicator electrode 10 is made of stabilized zirconia porcelain, the internal electrolyte 12 is made of potassium chloride solution, the internal electrode 11 is made of silver coated with silver chloride (AgCl), and the metal electrode body 20 is made of silver. The operating mechanism when the constructed indicator electrode 10 and metal electrode body 20 of the present invention are immersed in an aqueous solution as a measurement liquid will be described below. An electrochemical unipolar potential is generated at the internal electrode 11 in contact with the internal electrolyte 12. On the inner and outer surfaces of the sensitive membrane portion 10A of the indicator electrode 10, an electrochemical potential is generated at the respective membrane interfaces. This generation potential is determined by the equilibrium of ionic species at each interface. The potential on the inner surface of the membrane 10A becomes constant when the hydrogen ion concentration of the internal electrolyte is determined. The potential on the outer surface of the membrane 10A is determined by the fact that the activity concentration of the ionic species in the measurement liquid 15 is balanced on this membrane surface. A potential according to the Nernst equation is generated depending on the activity concentration. Generally, since the activity concentration of hydrogen ions in a dilute aqueous solution is proportional to the hydrogen ion concentration, there is a potential difference between the inner and outer surfaces of the sensitive membrane 10A according to the Nernst equation, which is proportional to the logarithm of the hydrogen ion concentration in the measurement solution. Occur. Further, a half cell corresponding to the activity of the ionic species in the aqueous solution is formed on the surface of the metal electrode 20 placed near the sensitive membrane 10A, and a unipolar potential is generated in this electrode 20. Therefore, the device configured in this manner can be viewed as a single battery as a whole. In this case, if the unipolar potential created by the metal electrode body 20 is not affected by the concentration of hydrogen ions in the measurement liquid, the potential difference measured by the device of the present invention will be proportional to the logarithm of the hydrogen ion concentration in the measurement liquid. It is. The present invention has developed a metal electrode body that is not easily affected by the hydrogen ion concentration in an aqueous solution and generates a stable potential. In this case, the metal electrode body is a metal whose surface is coated with silver, a silver alloy, or an oxide of silver and a silver alloy, or a metal base metal such as copper, aluminum, nickel, or iron plated or coated with silver or a silver alloy. The metal body is raised. Examples of effective reference electrodes include silver, alloys of silver and copper, alloys of silver and nickel, oxides of silver, and oxides of silver and copper. Representative examples of these include silver and alloys of silver and copper. It is preferable. When the indicator electrode and metal electrode body according to the present invention described above are used with appropriate fittings attached, the measuring device of the present invention is different from the prior art in that the internal electrolyte of the reference electrode does not leak into the measuring liquid. Does not have a liquid junction structure. The liquid in contact with it is made of a physically stable solid. A strikingly new hydrogen ion concentration measuring device can be provided. Note that among the reference numerals in FIG. 3, the same reference numerals as those in FIG. 2 indicate the same or similar components. (Example) Specific examples of the present invention will be described below. Example 1 In the configuration of the present invention shown in FIG. 2, reference numeral 10 is an indicator electrode, which is a cylindrical electrode having a structure in which one end is closed with stabilized zirconia doped with 8.5 moles of ittria and the other end is open. It is ceramic. The outer diameter is 8 mmφ, the inner diameter is 6 mmφ, the length is 150 mm, and the wall thickness at the closed end is 4.5 mm. 20 is a metal electrode body, which is a silver wire with a thickness of 1 mmφ, about 20 mm of which is exposed, and the rest is coated with ceramic. An internal electrolyte 12 and an internal electrode 11 are housed inside the indicator electrode 10 . Internal electrolyte 12 is a 3 mol/KCl aqueous solution,
The internal electrode 11 is a silver wire coated with AgCl and having a thickness of 1 mmφ. FIG. 3 shows the configuration of an experimental device for confirming the performance of the measuring device of the present invention. In Fig. 3, the test tank 30 is made of SUS and has an internal volume of about 1.8.
Approximately 1.3 ml of pure water is contained as the measurement liquid 15. This test chamber 30 includes an indicator electrode 10 and a metal electrode body 2.
The electrode terminals of both electrodes 10 and 20 are connected to an amplifier 25 having a high input resistance by a coaxial cable coated with Teflon. , amplifier 25
The output was measured using a pen recorder. Since the indicator electrode 10 generally has a high internal resistance, the amplifier 2
5 has a high input resistance circuit, and the indicator electrode 10
A shield 3 is attached to the lead wire connecting the amplifier 25 and the amplifier 25.
7 has been applied. Also, the metal electrode body 20 and the amplifier 25
The lead wires connecting these are also covered with a shield 24 for the purpose of preventing electromagnetic induction noise from entering. The chemical tanks 40, 41, and 42 are used to change the ion concentration in the aqueous solution of the measurement liquid. For example, the chemical tank 40 contains an acidic aqueous solution, the chemical tank 41 contains a neutral solution, and the chemical tank 42
contains a predetermined chemical solution called alkaline aqueous solution, 39 is a switching branch part, 38 is a chemical solution introduction part,
By operating the switching branch 39, any chemical solution can be introduced into the measurement liquid. Furthermore, it has the following functions and equipment to perform measurements under high temperature and high pressure conditions. 43 is a heating section, 44
45 is a thermometer, and 45 is a heating device that heats and controls the temperature of the liquid to be measured, and a chemical liquid introduction part 38.
A pressurizing device 47 capable of pressurized liquid feeding is arranged at
A pressure gauge 46 is attached to detect the internal pressure of the test chamber 30. Since the test tank 30 constitutes a pressurized container,
The members attached to this (indicator electrode 10, metal electrode body 20, pressure gauge 46, thermometer 44, and chemical liquid introduction part 38) are firmly attached with a sealing function that can sufficiently withstand these pressures at the attachment interface. has been done. In the experiment, an appropriate amount of acid or alkaline solution from chemical tanks 40, 41, and 42 was poured into the measuring liquid.
Figure 4 shows the results of measuring and recording the potential difference generated between both electrodes when the PH value was changed. Here, the water temperature was controlled at 95°C. The potential difference at this time was +95 mV. Next, an acid solution is added to this measurement solution to determine the pH of the measurement solution.
When the value becomes 2.4, the generated potential difference between both electrodes shows +340mV, and when the pH value of the measurement solution becomes 11.8 after adding an alkaline solution, the potential difference is -
It showed 163mV, and the acid solution was added again to dilute the measurement solution.
The potential difference when the PH value reached 2.3 was +344 mV. In addition, a stable potential difference was obtained, reaching the saturation value in a short period of time with respect to pH changes in the measurement solution. Example 2 In the configuration described in Example 1, a measurement system with the same configuration as above was assembled using a 1 mm diameter silver:copper=9:1 silver alloy as the metal electrode body to change the PH value of the measurement liquid. The potential difference generated between the two electrodes was measured. The results are shown in Table 1.

【表】 実施例1、2で述べた方法の特性を第5図に示
した。第5図でAで実施例1、Bは実施例2で述
べた本発明装置の特性曲線であり、Cは高温度用
につくられたPH測定用のガラス電極と液絡部がダ
ブルジヤンクシヨンをもつ比較電極で測定した時
の特性曲線である。同図に示すように金属電極体
として銀及び銀合金を使用した場合共に従来の方
法による測定値とほぼ同等の測定値を得ることが
できた。 実施例 3 実施例1及び2で示した構造と同様な構造をし
ていてその表面に銀、銀合金の酸化物皮膜を形成
した金属電極体を製作した。 この酸化皮膜の形成は金属露出部を十分に洗浄
した後恒温槽内にて100℃、30分間の加温を行い、
更に380℃、1時間の加熱処理して形成した。 この二種類の表面に酸化皮膜が形成されている
金属電極体を用いて、上記と同様な構成の測定シ
ステムを組立てて、測定液のPH値を変化させたと
きの両電極間に発生する電位差を測定した。その
結果は第2表の通りであつた。 同表に示すように表面に酸化皮膜が形成されて
いる電極体を用いた場合でも酸化皮膜のない銀、
銀合金からできている電極体を用いた場合とほぼ
同等の電位差が測定され、しかも測定液のPH変化
に対して短時間で安定した電位差が測定された。
[Table] The characteristics of the method described in Examples 1 and 2 are shown in FIG. In Figure 5, A is a characteristic curve of the device of the present invention described in Example 1, B is a characteristic curve of the device of the present invention described in Example 2, and C is a double junction between the glass electrode for PH measurement and the liquid junction made for high temperatures. This is a characteristic curve when measured using a reference electrode with . As shown in the figure, when silver and silver alloys were used as the metal electrode bodies, measured values almost equivalent to those obtained by the conventional method could be obtained. Example 3 A metal electrode body having a structure similar to that shown in Examples 1 and 2 and having an oxide film of silver or a silver alloy formed on its surface was manufactured. This oxide film is formed by thoroughly cleaning the exposed metal parts and heating them at 100℃ for 30 minutes in a constant temperature bath.
Further, it was formed by heat treatment at 380°C for 1 hour. Using these two types of metal electrode bodies with oxide films formed on their surfaces, a measurement system with the same configuration as above is assembled, and the potential difference that occurs between the two electrodes when the PH value of the measurement liquid is changed. was measured. The results were as shown in Table 2. As shown in the same table, even when using an electrode body with an oxide film formed on the surface, silver without an oxide film,
Almost the same potential difference as when using an electrode body made of a silver alloy was measured, and moreover, a stable potential difference was measured in a short period of time regardless of the pH change of the measurement solution.

【表】 比較実験例 1 以上に示した実施例と同様な手段を用いて、金
属電極体の材質、形状を変えて製作した場合につ
いても実験を行つた。金属電極体として白金を用
いた場合の比較実験では、測定液のPH値を純水→
PH2.2(酸性)→PH11.9(アルカリ性)→PH2.1(酸
性)に順次変化させると第6図に示すように発生
する電位差はPH変化時点で急激な変化を示すがそ
の値は安定せず漸次変化する急激なカーブをな
し、しかも測定液のPH値に対応した安定な電位差
を示さなかつた。 以上のことより、ある種の金属よりなる金属電
極を直接水溶液中に浸漬することで水溶液のPH値
が測定でき、又水溶液中の水素イオン濃度を測定
できることを示すものである。 比較実験例 2 実施例で説明した指示電極と金属電極を加熱、
加圧のできる圧力容器にとりつけその耐圧力性を
試験したところ温度200℃、圧力15.5Kg/cm2Gの
条件においても何等異常を示すものではなかつ
た。 本発明の装置によれば、指示電極、金属電極共
に材質的には安定したセラミツクと金属固体より
つくられ、構造的には前述したようなシンプルな
ものであるので、水溶液中の水素イオン濃度測定
やPH測定に適用すると、以下に述べる如く、極め
て優れた特徴と効果がある。 (1) 比較電極としての内部電解質をもたない、こ
れ故に液絡部をもたない。 (2) 測定液を汚染しないので測定液本来の水素イ
オン濃度の測定ができる。 (3) 高温度の液中で使用できる。 (4) 高圧力条件下の液中で使用できる。 (5) 極めてコンパクトに設計でき、その取扱いが
簡便容易となる。 (6) 液絡部のもつ本質的欠陥を一掃する。 (7) 使用中に特性変化が発生したりしたときに
は、金属電極表面を磨くとか洗浄とかの手段で
容易に特性の回復が可能となり、寿命の向上が
図れる。 以上説明したように本発明の水素イオン濃度測
定装置は、水溶液中の水素イオン濃度測定用セン
サー、各種工業水の水質管理用のPH測定、高温、
高圧力条件下での水溶液中の水素イオン濃度の直
接測定等に利用でき工業上有用である。
[Table] Comparative Experimental Example 1 Using the same method as in the above-described embodiments, experiments were also conducted in which metal electrode bodies were manufactured with different materials and shapes. In a comparative experiment using platinum as a metal electrode body, the PH value of the measurement solution was changed from pure water to
When changing the pH sequentially from PH2.2 (acidic) to PH11.9 (alkaline) to PH2.1 (acidic), the potential difference generated shows a sudden change at the time of the PH change, as shown in Figure 6, but the value remains stable. It formed a steep curve that gradually changed without any change, and moreover, it did not show a stable potential difference corresponding to the PH value of the measured solution. From the above, it is shown that by directly immersing a metal electrode made of a certain metal in an aqueous solution, the PH value of the aqueous solution can be measured, and the hydrogen ion concentration in the aqueous solution can also be measured. Comparative Experiment Example 2 Heating the indicator electrode and metal electrode explained in the example,
When it was installed in a pressurized pressure vessel and its pressure resistance was tested, no abnormality was observed even under conditions of a temperature of 200°C and a pressure of 15.5 kg/cm 2 G. According to the device of the present invention, both the indicator electrode and the metal electrode are made of stable ceramic and metal solid materials, and the structure is simple as described above, so it is possible to measure the hydrogen ion concentration in an aqueous solution. When applied to PH measurement, it has extremely excellent features and effects as described below. (1) It does not have an internal electrolyte as a reference electrode, and therefore does not have a liquid junction. (2) Since the measurement solution is not contaminated, the original hydrogen ion concentration of the measurement solution can be measured. (3) Can be used in high temperature liquids. (4) Can be used in liquids under high pressure conditions. (5) It can be designed to be extremely compact and its handling is simple and easy. (6) Eliminate essential defects in the liquid junction. (7) When characteristics change during use, the characteristics can be easily restored by polishing or cleaning the metal electrode surface, and the lifespan can be improved. As explained above, the hydrogen ion concentration measuring device of the present invention can be used as a sensor for measuring hydrogen ion concentration in an aqueous solution, a PH measurement for water quality management of various industrial waters, a high temperature sensor,
It can be used for direct measurement of hydrogen ion concentration in aqueous solutions under high pressure conditions, and is industrially useful.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は、従来の測定装置の概略を示す構成
図、第2図は、本発明の構成を示すための説明
図、第3図は、本発明においてその性能を調査す
るために用いた試験装置の概略説明図、第4図は
本発明の銀電極を使用し、測定液のPHを酸性、ア
ルカリ性、酸性に順次変化したときの電位差測定
図、第5図は、本発明の実施例による測定結果を
示すグラフで水溶液のPH値の変化に対応した出力
電位差の関係を示す特性図である。第6図は白金
電極(比較例)を使用し、第5図と同様に液を純
水、酸性、アルカリ性、酸性に順次変化したとき
の電位差測定図である。 1……指示電極、2……比較電極、3……内部
電極、4……内部電解質、5……液絡部、6……
電位差計、10……指示電極、11……内部電
極、12……内部電解質、13……端子、14…
…シールド、15……測定液、16……測定用容
器、20……金属電極体、21……絶縁被覆部、
22……絶縁部、23……端子、24……シール
ド、25……増巾器、26……電圧計、30……
試験槽、37……シールド、38……薬液導入
部、39……切換(分岐)部、40,41,42
……薬液槽、43……加熱部、44……温度計、
45……加熱装置、47……加圧装置。
FIG. 1 is a configuration diagram showing an outline of a conventional measuring device, FIG. 2 is an explanatory diagram showing the configuration of the present invention, and FIG. 3 is a test used to investigate the performance of the present invention. A schematic explanatory diagram of the device, Figure 4 is a potential difference measurement diagram when the pH of the measuring solution was changed sequentially from acidic to alkaline to acidic using the silver electrode of the present invention, and Figure 5 is a diagram of the potential difference measurement according to an example of the present invention. FIG. 3 is a graph showing the measurement results, and is a characteristic diagram showing the relationship between the output potential difference corresponding to the change in the PH value of the aqueous solution. FIG. 6 is a potential difference measurement diagram when a platinum electrode (comparative example) is used and the liquid is sequentially changed to pure water, acidic, alkaline, and acidic in the same way as FIG. 5. 1... Indicator electrode, 2... Reference electrode, 3... Internal electrode, 4... Internal electrolyte, 5... Liquid junction, 6...
potentiometer, 10... indicator electrode, 11... internal electrode, 12... internal electrolyte, 13... terminal, 14...
... Shield, 15 ... Measurement liquid, 16 ... Measurement container, 20 ... Metal electrode body, 21 ... Insulation coating part,
22... Insulation section, 23... Terminal, 24... Shield, 25... Amplifier, 26... Voltmeter, 30...
Test tank, 37... Shield, 38... Chemical solution introduction part, 39... Switching (branching) part, 40, 41, 42
...chemical tank, 43 ... heating section, 44 ... thermometer,
45... Heating device, 47... Pressurizing device.

Claims (1)

【特許請求の範囲】 1 測定装置の一方の電極端子に接続される端子
をもつ水素イオン濃度測定用指示電極と、他方の
電極端子に接続される端子をもつた金属電極体と
を水溶液中に直接浸漬して両端子間に発生する電
位差を上記測定装置で測定することにより水溶液
中の水素イオン濃度を測定する装置において、水
素イオン濃度測定用指示電極は一端開放で他端に
閉塞端を備えた容器とその内部に内部電極と内部
電解質とを有し、その閉塞端は少なくとも酸素イ
オン伝導性固体電解質から形成され、かつ、他方
の金属電極体の上記水溶液に接触する表面は銀、
銀合金又は銀、銀合金の酸化物より選択された何
れかが被覆されていることを特徴とする水素イオ
ン濃度測定装置。 2 固体電解質は安定化ジルコニアである特許請
求の範囲第1項記載の水素イオン濃度測定装置。 3 金属電極体は金属地金の上に銀、銀合金ある
いはその酸化物を被覆又は積層した複合金属体で
ある特許請求の範囲第1項記載の水素イオン濃度
測定装置。 4 金属電極体は絶縁体に取付けられ、この絶縁
体が測定装置への取付部材となる特許請求の範囲
第1項又は第3項記載の水素イオン濃度測定装
置。 5 上記金属電極体の液浸漬部の少なくとも一部
が絶縁体で被覆されている特許請求の範囲第1項
又は第3項記載の水素イオン濃度測定装置。
[Claims] 1. An indicator electrode for hydrogen ion concentration measurement having a terminal connected to one electrode terminal of a measuring device and a metal electrode body having a terminal connected to the other electrode terminal are placed in an aqueous solution. In a device for measuring hydrogen ion concentration in an aqueous solution by directly immersing it and measuring the potential difference generated between both terminals with the measuring device, the indicator electrode for hydrogen ion concentration measurement has one end open and the other end closed. The container has an internal electrode and an internal electrolyte therein, the closed end of which is formed of at least an oxygen ion conductive solid electrolyte, and the surface of the other metal electrode body that contacts the aqueous solution is made of silver,
A hydrogen ion concentration measuring device characterized in that it is coated with one selected from a silver alloy or an oxide of silver or a silver alloy. 2. The hydrogen ion concentration measuring device according to claim 1, wherein the solid electrolyte is stabilized zirconia. 3. The hydrogen ion concentration measuring device according to claim 1, wherein the metal electrode body is a composite metal body in which silver, a silver alloy, or an oxide thereof is coated or laminated on a metal base metal. 4. The hydrogen ion concentration measuring device according to claim 1 or 3, wherein the metal electrode body is attached to an insulator, and this insulator serves as a mounting member to the measuring device. 5. The hydrogen ion concentration measuring device according to claim 1 or 3, wherein at least a portion of the liquid immersion portion of the metal electrode body is coated with an insulator.
JP2772383A 1983-02-23 1983-02-23 Hydrogen ion concentration measuring apparatus Granted JPS59154351A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2772383A JPS59154351A (en) 1983-02-23 1983-02-23 Hydrogen ion concentration measuring apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2772383A JPS59154351A (en) 1983-02-23 1983-02-23 Hydrogen ion concentration measuring apparatus

Publications (2)

Publication Number Publication Date
JPS59154351A JPS59154351A (en) 1984-09-03
JPH0452407B2 true JPH0452407B2 (en) 1992-08-21

Family

ID=12228934

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2772383A Granted JPS59154351A (en) 1983-02-23 1983-02-23 Hydrogen ion concentration measuring apparatus

Country Status (1)

Country Link
JP (1) JPS59154351A (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3507183C1 (en) * 1985-03-01 1990-11-15 Drägerwerk AG, 2400 Lübeck Metal / metal oxide measuring electrode for pH measurement
JPH0656375B2 (en) * 1987-12-23 1994-07-27 東伸工業株式会社 Zirconia electrode and pH measuring device
US5502388A (en) * 1993-02-04 1996-03-26 Hoechst Aktiengesellschaft Method of measuring the pH value of a test solution with glass-electrode measuring cells and of simultaneously calibrating the measuring cells
KR100759926B1 (en) 2005-01-19 2007-09-18 대윤계기산업 주식회사 Hydrogen ion-selective membrane and method for preparing thereof
DE502006008890D1 (en) * 2006-12-22 2011-03-24 Mettler Toledo Ag Method and device for monitoring an electrochemical half-cell

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5214475U (en) * 1975-07-18 1977-02-01
JPS5677751A (en) * 1979-10-12 1981-06-26 Gen Electric Sensor for hydrogen ion

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5214475U (en) * 1975-07-18 1977-02-01
JPS5677751A (en) * 1979-10-12 1981-06-26 Gen Electric Sensor for hydrogen ion

Also Published As

Publication number Publication date
JPS59154351A (en) 1984-09-03

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