JPH0239740B2 - - Google Patents
Info
- Publication number
- JPH0239740B2 JPH0239740B2 JP57072131A JP7213182A JPH0239740B2 JP H0239740 B2 JPH0239740 B2 JP H0239740B2 JP 57072131 A JP57072131 A JP 57072131A JP 7213182 A JP7213182 A JP 7213182A JP H0239740 B2 JPH0239740 B2 JP H0239740B2
- Authority
- JP
- Japan
- Prior art keywords
- oxygen concentration
- electrolyte
- lead
- acetic acid
- concentration meter
- 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
Links
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 69
- 239000001301 oxygen Substances 0.000 claims description 53
- 229910052760 oxygen Inorganic materials 0.000 claims description 53
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 52
- 239000003792 electrolyte Substances 0.000 claims description 31
- 239000007864 aqueous solution Substances 0.000 claims description 13
- 239000007789 gas Substances 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 9
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 229910000464 lead oxide Inorganic materials 0.000 claims description 4
- 239000008151 electrolyte solution Substances 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- 229910052783 alkali metal Inorganic materials 0.000 claims description 2
- 150000001340 alkali metals Chemical class 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims 2
- 229910021529 ammonia Inorganic materials 0.000 claims 1
- 229910044991 metal oxide Inorganic materials 0.000 claims 1
- 150000004706 metal oxides Chemical class 0.000 claims 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical class [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 claims 1
- 239000001257 hydrogen Substances 0.000 description 24
- 229910052739 hydrogen Inorganic materials 0.000 description 24
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 22
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 14
- 239000000047 product Substances 0.000 description 11
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 8
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 7
- 239000001569 carbon dioxide Substances 0.000 description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 235000011056 potassium acetate Nutrition 0.000 description 4
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 239000001632 sodium acetate Substances 0.000 description 3
- 235000017281 sodium acetate Nutrition 0.000 description 3
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical class N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000003411 electrode reaction Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 229940046892 lead acetate Drugs 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- MFEVGQHCNVXMER-UHFFFAOYSA-L 1,3,2$l^{2}-dioxaplumbetan-4-one Chemical compound [Pb+2].[O-]C([O-])=O MFEVGQHCNVXMER-UHFFFAOYSA-L 0.000 description 1
- 239000005695 Ammonium acetate Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910000004 White lead Inorganic materials 0.000 description 1
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229940043376 ammonium acetate Drugs 0.000 description 1
- 235000019257 ammonium acetate Nutrition 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920000840 ethylene tetrafluoroethylene copolymer Polymers 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 150000002611 lead compounds Chemical class 0.000 description 1
- RYZCLUQMCYZBJQ-UHFFFAOYSA-H lead(2+);dicarbonate;dihydroxide Chemical compound [OH-].[OH-].[Pb+2].[Pb+2].[Pb+2].[O-]C([O-])=O.[O-]C([O-])=O RYZCLUQMCYZBJQ-UHFFFAOYSA-H 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
Landscapes
- 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)
- Measuring Oxygen Concentration In Cells (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
Description
【発明の詳細な説明】
本発明は酸素濃度計、特にガルバニツク式酸素
濃度計に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen concentration meter, and more particularly to a galvanic oxygen concentration meter.
酸素濃度計には、ガルバニツク式、ポーラログ
ラフ式、磁気式あるいはジルコニア固体電解質式
などさまざまな方式のものがある。 There are various types of oxygen concentration meters, such as galvanic type, polarographic type, magnetic type, and zirconia solid electrolyte type.
その中で、ガルバニツク式酸素濃度計は一般に
手軽で安価であり、かつ常温で作動するので、広
い分野で利用されている。 Among these, galvanic oxygen concentration meters are generally easy to use, inexpensive, and operate at room temperature, so they are used in a wide range of fields.
ガルバニツク式酸素濃度計は酸素の電気化学的
還元に有効な金属からなる正極と鉛からなる負極
と電解液とからなる電池で構成され、正極と負極
との間に一定の抵抗を接続したとき、そこに流れ
る電流と酸素濃度との間に直線性があることを利
用している。 A galvanic oxygen concentration meter consists of a battery consisting of a positive electrode made of a metal effective in the electrochemical reduction of oxygen, a negative electrode made of lead, and an electrolyte.When a certain resistance is connected between the positive and negative electrodes, It takes advantage of the fact that there is linearity between the current flowing there and the oxygen concentration.
従来のガルバニツク式酸素濃度計の寿命は一般
に６ケ月〜10ケ月と非常に短かいのが欠点であつ
た、これは電解液として、水酸化カリウムあるい
は水酸化ナトリウムの水溶液が用いられていたこ
とに由来する。以下この点について説明する。 The disadvantage of conventional galvanic oxygen concentration meters was that they generally had a very short lifespan of 6 to 10 months.This was due to the fact that an aqueous solution of potassium hydroxide or sodium hydroxide was used as the electrolyte. Originates from This point will be explained below.
すなわちアルカリ電解液を用いた場合、正極で
は、
O2＋2H2O＋4e-→4OH- …(1)
なる反応が起り、負極では
2Pb＋4OH-→2PbO＋2H2O＋4e- …(2)
なる反応が起る。負極反応生成物であるPbOは電
解液中に溶解して、鉛極の表面は常に更新され
る。ところが、電解液が負極反応生成物で飽和さ
れると、負極表面は不働態化され、負極の過電圧
が増大するために、正極と負極との間に流れる電
流が変化し、酸素濃度と電流との一定の関係が崩
れ、酸素濃度計の寿命が尽きる。 That is, when an alkaline electrolyte is used, the following reaction occurs at the positive electrode: O 2 +2H 2 O+4e - →4OH - (1), and the following reaction occurs at the negative electrode: 2Pb+4OH - →2PbO+2H 2 O+4e - (2). PbO, a negative electrode reaction product, is dissolved in the electrolyte, and the surface of the lead electrode is constantly renewed. However, when the electrolyte is saturated with negative electrode reaction products, the negative electrode surface becomes passivated and the overvoltage of the negative electrode increases, causing a change in the current flowing between the positive and negative electrodes, causing a change in oxygen concentration and current. The constant relationship between the two will be broken, and the life of the oxygen concentration meter will end.
従来、アルカリ電解液を用いたガルバニツク式
酸素濃度計の寿命が短かかつたのは、負極生成物
であるPbOのアルカリ水溶液に対する溶解度がた
かだか0.1モル／程度と小さかつたからに他な
らない。 Conventional galvanic oximeters using alkaline electrolytes had short lifespans because the solubility of PbO, the negative electrode product, in alkaline aqueous solutions was as low as 0.1 mol/at most.
これに対してガルバニツク式酸素濃度計の電解
液として、酢酸が用いられている例もある。（特
開昭49−53891）
電解液として酢酸水溶液を用いた場合には、正
極では
O2＋4H+＋4e-→2H2O …(3)
なる反応が起り、負極では
2Pb＋2H2O→2PbO＋4H+＋4e- …(4)
なる反応が起る。 On the other hand, there are examples in which acetic acid is used as the electrolyte in galvanic oxygen concentration meters. (JP 49-53891) When an acetic acid aqueous solution is used as the electrolyte, the following reaction occurs at the positive electrode: O 2 +4H + +4e - →2H 2 O …(3), and at the negative electrode, the reaction 2Pb + 2H 2 O → 2PbO + 4H + + 4e - …(4) A reaction occurs.
いずれにしても、負極の反応生成物は、アルカ
リ電解液を用いた場合と同様に酸化鉛（PbO）で
ある。 In any case, the reaction product of the negative electrode is lead oxide (PbO), as in the case of using an alkaline electrolyte.
酸化鉛（PbO）の酢酸水溶液に対する溶解度
は、2.1モル／であり、アルカリ電解液に対す
る溶解度の約20倍となる。したがつて酢酸を電解
液とすれば、ガルバニツク式酸素濃度計の寿命は
非常に長くなることが推定される。ところが従来
酢酸を電解液としたガルバニツク式酸素濃度計は
実用に供されていないし、その寿命についての文
献も見当たらない。 The solubility of lead oxide (PbO) in an acetic acid aqueous solution is 2.1 mol/about 20 times the solubility in an alkaline electrolyte. Therefore, it is estimated that if acetic acid is used as the electrolyte, the life of the galvanic oxygen concentration meter will be significantly longer. However, conventional galvanic oxygen concentration meters using acetic acid as an electrolyte have not been put into practical use, and no literature has been found regarding their service life.
これは酢酸水溶液の電導度が小さすぎて、（18
℃，３モル／で16×10-4Ω-1cm-1）酸素濃度計
の内部抵抗が大きくなりすぎるためである。 This is because the conductivity of the acetic acid aqueous solution is too low (18
This is because the internal resistance of the oxygen concentration meter becomes too large.
酢酸水溶液が実用に供されなかつたもうひとつ
の理由は、正極から水素が発生し易いからであ
る。すなわち正極の水素発生平衡電位は次の(5)式
で与えられる。 Another reason why aqueous acetic acid solutions have not been put to practical use is that hydrogen is easily generated from the positive electrode. That is, the hydrogen generation equilibrium potential of the positive electrode is given by the following equation (5).
ここで、
EH……25℃における水素発生平衡電位
PB2……水素の分圧
PH……電解液のPH
つまり(5)式において、PHが小さくなればなるほ
ど、正極の水素発生平衡電位が貴になり、それだ
け正極から水素が発生し易くなる。酢酸水溶液の
ようにPHが小さい溶液を電解液とすると、殊に酸
素濃度の低い検知気体の酸素濃度を測定する場合
には正極の電位がかなり卑となるので、水素が発
生し易くなる。 Here, E H ...Equilibrium hydrogen generation potential at 25℃ P B2 ...Partial pressure of hydrogen PH...PH of the electrolyte In other words, in equation (5), the smaller the PH, the more the equilibrium hydrogen generation potential of the positive electrode increases. The higher the concentration of hydrogen, the more likely it is that hydrogen will be generated from the positive electrode. When a solution with a low pH, such as an aqueous acetic acid solution, is used as the electrolyte, the potential of the positive electrode becomes quite base, especially when measuring the oxygen concentration of a sensing gas with a low oxygen concentration, making it easy to generate hydrogen.
なお、電解液として、酢酸と酢酸ソーダと酢酸
鉛の混合水溶液を用いる例［アール，エルスワー
ス，「ザ・ケミカルエンジニア」（Ｒ，Elsworth，
The Chemical Engineer，）２月号，63−71
（1972）］もあるが、この場合には、酢酸と酢酸ソ
ーダとの混合比が5.0M対0.5Mであるため、PHが
３であり（第65頁右欄）やはり水素が発生する。 An example of using a mixed aqueous solution of acetic acid, sodium acetate, and lead acetate as the electrolyte [R, Ellsworth, "The Chemical Engineer"]
The Chemical Engineer, February issue, 63-71
(1972)], but in this case, since the mixing ratio of acetic acid and sodium acetate is 5.0M to 0.5M, the pH is 3 (page 65, right column), and hydrogen is also generated.
上記引例では、センサが密閉されていなくて、
開放構造をとつていることが明示されている（第
65頁左欄、図１および図１の下部の段落）。した
がつて、水素が発生していても、そのことが認識
されていないことが推定されるし、またあまり問
題とならない。これは、この引例に記載されてい
る酸素センサが溶存酸素の測定のみを対象として
いることと無関係ではない。いずれにしても、気
相中の酸素濃度を測定する場合を含めて、一般に
密閉型にすることが望ましいが、密閉型の酸素セ
ンサの場合には、上述の電解液のPHでは水素が発
生するし、そのことが、決定的な問題となる。 In the above cited example, the sensor is not sealed,
It is clearly stated that it has an open structure (No.
Page 65 left column, Figure 1 and the bottom paragraph of Figure 1). Therefore, even if hydrogen is generated, it is presumed that it is not recognized and does not pose much of a problem. This is not unrelated to the fact that the oxygen sensor described in this reference is intended only for measuring dissolved oxygen. In any case, it is generally desirable to use a closed type oxygen sensor, including when measuring oxygen concentration in the gas phase, but in the case of a closed type oxygen sensor, hydrogen is generated at the pH of the electrolyte described above. However, this becomes a crucial issue.
本発明は、ガルバニツク式酸素センサの寿命が
電解液の酸化鉛に対する溶解度によつて決定され
ることと電解液の組成を適切に選択しないと正極
から水素が発生するという発見に基づいてなされ
たものであり、酢酸とアルカリ金属もしくはアン
モニアの酢酸塩と酸化鉛もしくは鉛塩との混合水
溶液であり、かつそのPHが４〜７の混合水溶液を
電解液とすることによつて、寿命が非常に長く、
かつ水素の発生が起こらない密閉型のガルバニツ
ク式酸素濃度計を提供するものである。 The present invention was made based on the discovery that the life of a galvanic oxygen sensor is determined by the solubility of the electrolyte in lead oxide, and that hydrogen is generated from the positive electrode if the composition of the electrolyte is not appropriately selected. It is a mixed aqueous solution of acetic acid, alkali metal or ammonia acetate, and lead oxide or lead salt, and by using the mixed aqueous solution with a pH of 4 to 7 as the electrolyte, it has a very long life. ,
The present invention also provides a closed type galvanic oxygen concentration meter that does not generate hydrogen.
酢酸に酢酸カリ、酢酸ソーダ、酢酸リチウムあ
るいは酢酸アンモニウムの如き酢酸塩を添加する
と、酢酸単独の場合に比較して電導度が大巾に上
る。例えば酢酸単独の場合（18℃、３モル／）
には16×10-4Ω-1cm-1だつた電導度が、４モル／
の酢酸カリを混入すると1250×10-4Ω-1cm-1と
２桁上昇する。 Addition of an acetate such as potassium acetate, sodium acetate, lithium acetate, or ammonium acetate to acetic acid greatly increases the conductivity compared to acetic acid alone. For example, in the case of acetic acid alone (18℃, 3 mol/)
has a conductivity of 16×10 -4 Ω -1 cm -1 , which is 4 mol/
When potassium acetate is mixed in, the value increases by two orders of magnitude to 1250×10 -4 Ω -1 cm -1 .
酢酸の濃度は４〜10モル／の範囲、酢酸塩の
濃度は、１〜10モル／の範囲が適当である。 The concentration of acetic acid is suitably in the range of 4 to 10 mol/, and the concentration of acetate is suitably in the range of 1 to 10 mol/.
一方、酢酸単独あるいは、少量の酢酸塩を添加
しても、そのPHは２〜３と非常に小さく、酢酸塩
をかなり添加し、PHを４〜７にもつていくと、正
極からの水素発生の可能性が極めて小さくなる。 On the other hand, even if acetic acid alone or a small amount of acetate is added, the pH is very low at 2 to 3. If a large amount of acetate is added and the pH is raised to 4 to 7, hydrogen generation from the positive electrode occurs. The possibility of this becomes extremely small.
また酢酸と酢酸塩との混合溶液を用いると酢酸
根の緩衝作用により溶液のPH変化が少ないので、
酸素濃度計の出力が安定し易いという長所につな
がる。 In addition, when a mixed solution of acetic acid and acetate is used, there is little change in the pH of the solution due to the buffering effect of the acetic acid group.
This leads to the advantage that the output of the oxygen concentration meter is easily stabilized.
酢酸と酢酸塩との混合水溶液によつて、PHを７
に近づけることにより水素発生の可能性は小さく
なるが、鉛イオンの添加によつて正極からの水素
発生はより完全に回避される。 Adjust the pH to 7 with a mixed aqueous solution of acetic acid and acetate.
However, by adding lead ions, hydrogen generation from the positive electrode can be more completely avoided.
つまり酸素濃度がほとんど０％に近い領域で
は、酸素濃度計の正極と負極とは抵抗を介して接
続されているので、同一の電位となる。したがつ
て、鉛負極の電位をより貴にもつていつてやれば
それだけ水素発生の可能性が小さくなる。鉛の平
衡電位は次式のように表わされ、
EPb／Pb++＝−0.367＋0.0296log〔Pb++〕（VVS
SEC）…(6)
ここで
EPb／Pb++……25℃における鉛の平衡電位
〔Pb++〕……電解液中の鉛イオンの活量
鉛イオン添加量が多ければ多いほど鉛極の電
位、換言すれば正極の電位がより貴になることが
わかる。 In other words, in a region where the oxygen concentration is almost 0%, the positive and negative electrodes of the oximeter are connected via a resistor, so they have the same potential. Therefore, the more noble the potential of the lead negative electrode is, the lower the possibility of hydrogen generation. The equilibrium potential of lead is expressed as follows: EPb/Pb ++ = −0.367 + 0.0296log [Pb ++ ] (V VS
SEC)...(6) Here, EPb/Pb ++ ... Equilibrium potential of lead at 25℃ [Pb ++ ]...Activity of lead ions in the electrolyte The greater the amount of lead ions added, the more It can be seen that the potential, in other words, the potential of the positive electrode becomes more noble.
たとえば５モル／の酢酸と４モル／の酢酸
カリの混合水溶液における鉛負極の電位は約−
0.92V（vs SCE）となり、同じPH（6.1）における
水素発生平衡電位（−0.60V vs SCE）より卑で
あるため、正極からの水素発生の可能性が若干残
されているが、上述の電解液に0.1モル／の酢
酸塩を添加すると鉛極の電位は−0.59V（vsSCE）
となり水素発生平衡電位より貴になるので、水素
は絶対発生しなくなる。 For example, in a mixed aqueous solution of 5 mol/acetic acid and 4 mol/potassium acetate, the potential of the lead negative electrode is approximately -
0.92V (vs SCE), which is less noble than the hydrogen generation equilibrium potential (-0.60V vs SCE) at the same pH (6.1), so there is still some possibility of hydrogen generation from the positive electrode. When 0.1 mol/acetate is added to the solution, the potential of the lead electrode becomes -0.59V (vsSCE)
Since the potential is nobler than the hydrogen generation equilibrium potential, hydrogen will never be generated.
電解液に添加すべき鉛化合物としては、酸化鉛
あるいは鉛塩が適当であるが、殊に酢酸鉛がよ
い。添加量としては0.01〜１モル／の範囲がよ
い。 As the lead compound to be added to the electrolytic solution, lead oxide or lead salt is suitable, and lead acetate is particularly preferred. The amount added is preferably in the range of 0.01 to 1 mol/.
以上述べたように、本発明は寿命が長く、内部
抵抗が低く、かつ水素発生が起らない酸素濃度計
を提供するものであが、そればかりでなく、検体
雰囲気中に炭酸ガスを含む場合にも使用できる酸
素濃度計を提供できるという点にも長所がある。 As described above, the present invention provides an oxygen concentration meter that has a long life, low internal resistance, and does not generate hydrogen. Another advantage is that it can provide an oxygen concentration meter that can be used for
すなわち、従来のようにアルカリ電解液を用い
た酸素濃度計の場合、検体雰囲気中に比較的多量
の炭酸ガスが含まれているときには、負極では、
前述の(2)式のように、PbOが生成する代りに、不
溶性の炭酸鉛（PbCO3）あるいは塩基性炭酸鉛
（Pb2CO3（OH）2）が生成し、負極の過電圧が著し
く大きくなつてしまつて酸素濃度を測定し得なく
なるという欠点があつた。 In other words, in the case of a conventional oxygen concentration meter that uses an alkaline electrolyte, when the sample atmosphere contains a relatively large amount of carbon dioxide, the negative electrode
As shown in equation (2) above, instead of PbO, insoluble lead carbonate (PbCO 3 ) or basic lead carbonate (Pb 2 CO 3 (OH) 2 ) is generated, and the overvoltage at the negative electrode becomes significantly large. The disadvantage was that it became too old to measure oxygen concentration.
これ対し、本発明では酸性電解液を用いている
ので炭酸塩は生成せず、本発明にかかる酸素濃度
計は炭酸ガスを多量に含む雰囲気中の酸素濃度を
測定することができる。 In contrast, in the present invention, since an acidic electrolyte is used, carbonate is not generated, and the oxygen concentration meter according to the present invention can measure the oxygen concentration in an atmosphere containing a large amount of carbon dioxide gas.
酸素濃度計の構造はたとえば第１図で示され
る。 The structure of the oximeter is shown in FIG. 1, for example.
第１図において、正極１は銀、白金、金等酸素
の還元に有効な金属からなつている。あるいは
銅、ニツケル等の金属にこれらの金属をメツキし
てもよい。負極２は高純度の鉛からなつている。
３は電解液である。 In FIG. 1, a positive electrode 1 is made of a metal effective in reducing oxygen, such as silver, platinum, or gold. Alternatively, metals such as copper and nickel may be plated with these metals. The negative electrode 2 is made of high purity lead.
3 is an electrolytic solution.
防水性隔膜４は、ポリエチレン、ポリプロピレ
ン、ポリ四弗化エチレン、四弗化エチレン−六弗
化プロピレンコポリマー、四弗化エチレン−エチ
レンコポリマー等のプラスチツクフイルムからな
り、Ｏ−リング５で以てポリ塩化ビニル製のホル
ダー６に固定されている。 The waterproof diaphragm 4 is made of a plastic film such as polyethylene, polypropylene, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, etc., and is made of polychloride with an O-ring 5. It is fixed to a vinyl holder 6.
防水性隔膜４は、検体気体あるいは溶液中の酸
素の拡散を適度に制約する働きと、電解液の漏出
を防止する機能をもつている。 The waterproof diaphragm 4 has the function of appropriately restricting the diffusion of the sample gas or oxygen in the solution, and the function of preventing leakage of the electrolyte.
正極１と負極２とは、抵抗７を介して接続さ
れ、の抵抗７を流れる電流、換言すれば抵抗７の
両端部の電圧によつて酸素濃度が測定される。 The positive electrode 1 and the negative electrode 2 are connected through a resistor 7, and the oxygen concentration is measured based on the current flowing through the resistor 7, in other words, the voltage across both ends of the resistor 7.
以下本発明の一実施例について詳述する。 An embodiment of the present invention will be described in detail below.
実施例：第１図に示す構造の酸素濃度計におい
て、正極として、作用面積が0.2cm2の白金板を用
い、負極として、作用面積が５cm2の鉛を用いた。
防水隔膜としては厚さ20μの四弗化エチレン−六
弗化プロピレンコポリマー膜を用いた。 Example: In an oxygen concentration meter having the structure shown in FIG. 1, a platinum plate with an active area of 0.2 cm 2 was used as the positive electrode, and a lead plate with an active area of 5 cm 2 was used as the negative electrode.
As the waterproof diaphragm, a tetrafluoroethylene-hexafluoropropylene copolymer membrane with a thickness of 20 μm was used.
また電解液として５モル／の酢酸と４モル／
の酢酸カリウムと0.1モル／の酢酸との混合
水溶液を用い、電解液量を６mlとした。電解液の
PHは6.2であつた。酸素濃度計の内部抵抗は100Ω
であつた。 In addition, as an electrolyte, 5 mol/acetic acid and 4 mol/
An aqueous mixed solution of potassium acetate and acetic acid was used, and the amount of electrolyte was set to 6 ml. of electrolyte
The pH was 6.2. The internal resistance of the oxygen concentration meter is 100Ω
It was hot.
次に本発明の実施例によつて得られた酸素濃度
計と従来品である４モル／の水酸化カリウム水
溶液を電解液とした酸素濃度計との寿命試験比較
をおこなつた。 Next, a life test comparison was conducted between the oxygen concentration meter obtained according to the embodiment of the present invention and a conventional oxygen concentration meter using a 4 mol/aqueous potassium hydroxide solution as an electrolyte.
試験の組合わせは次のようにした。 The test combinations were as follows.
Ａ：従来品、空気中
Ｂ：従来品、10％炭酸ガス、21％酸素、69％窒
素中
Ｃ：本発明品、空気中
Ｄ：本発明品、10％炭酸ガス、21％酸素、69％
窒素中
試験結果を第２図に示す。 A: Conventional product, in air B: Conventional product, 10% carbon dioxide, 21% oxygen, 69% nitrogen C: Inventive product, in air D: Inventive product, 10% carbon dioxide, 21% oxygen, 69%
Figure 2 shows the test results in nitrogen.
すなわち、従来の水酸化カリウムの水溶液を電
解液として酸素濃度計よりも、本発明にかかるそ
れの方が、圧倒的に寿命が長いことがわかる。ま
た従来品の場合、炭酸ガスが存在すると、極端に
寿命が短かくなるのに対し、本発明品の場合には
炭酸ガスの影響が認められないことがわかる。 That is, it can be seen that the life of the device according to the present invention is overwhelmingly longer than the conventional oxygen concentration meter using an aqueous solution of potassium hydroxide as the electrolyte. Furthermore, in the case of the conventional product, the presence of carbon dioxide gas causes an extremely short life, whereas in the case of the product of the present invention, no influence of carbon dioxide gas is observed.
一方、４モル／の酢酸水溶液の単独を電解液
とした酸素濃度計と実施例で得られた酸素濃度計
をそれぞれ0.01％の酸素濃度の気体雰囲気中にお
いたとき、前者の場合には正極から水素の発生が
観察されたのに対し、後者の場合には水素は発生
しなかつた。 On the other hand, when the oxygen concentration meter using only 4 mol/aqueous acetic acid solution as the electrolyte and the oxygen concentration meter obtained in the example were placed in a gas atmosphere with an oxygen concentration of 0.01%, in the case of the former, the positive electrode Hydrogen evolution was observed, whereas in the latter case no hydrogen was evolved.
以上詳述せる如く、本発明は寿命が非常に長
く、炭酸ガスの影響を受けず、しかも水素の発生
が起らない酸素濃度計を提供するもので、その工
業的価値極めて大である。 As detailed above, the present invention provides an oxygen concentration meter that has a very long life, is not affected by carbon dioxide gas, and does not generate hydrogen, and has extremely great industrial value.
なお、上述の試験例では気相中の酸素濃度を測
定する場合について述べたが、溶液中の溶存酸素
を測定する上でも本発明にかかる酸素濃度計の利
点が発揮される。 In addition, although the above-mentioned test example described the case of measuring the oxygen concentration in the gas phase, the advantages of the oxygen concentration meter according to the present invention are also exhibited when measuring dissolved oxygen in a solution.
第１図は、本発明の一実施例にかかる酸素濃度
計の断面構造を示し、第２図は、本発明品と従来
品との寿命試験結果の比較を示す。
１……正極、２……負極、３……電解液、４…
…防水隔膜、５……Ｏリング、６……ホルダー、
７……抵抗、Ａ，Ｂ……従来品、Ｃ，Ｄ……本発
明品。
FIG. 1 shows a cross-sectional structure of an oxygen concentration meter according to an embodiment of the present invention, and FIG. 2 shows a comparison of life test results between the product of the present invention and a conventional product. 1... Positive electrode, 2... Negative electrode, 3... Electrolyte, 4...
...Waterproof diaphragm, 5...O ring, 6...Holder,
7...Resistance, A, B...Conventional products, C, D...Products of the present invention.
Claims (1)
金属酸化物を正極とし、鉛を負極とし、酢酸とア
ルカリ金属もしくはアンモニアの酢酸塩との混合
水溶液であつて、かつそのPHが４〜７である混合
水溶液を電解液としてなることを特徴とする気体
中あるいは溶液中の酸素濃度を測定するための酸
素濃度計。 ２ 特許請求の範囲第１項記載の酸素濃度計にお
いて、電解液中に酸化鉛もしくは鉛塩を添加して
なることを特徴とする酸素濃度計。[Scope of Claims] 1. A mixed aqueous solution of acetic acid and an acetate of an alkali metal or ammonia, with a metal or metal oxide highly active in reducing oxygen as a positive electrode, lead as a negative electrode, and its PH An oxygen concentration meter for measuring the oxygen concentration in a gas or solution, characterized in that the electrolyte is a mixed aqueous solution in which the ratio is 4 to 7. 2. The oxygen concentration meter according to claim 1, characterized in that lead oxide or lead salt is added to the electrolytic solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57072131A JPS58187846A (en) | 1982-04-27 | 1982-04-27 | Oxygen densitometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57072131A JPS58187846A (en) | 1982-04-27 | 1982-04-27 | Oxygen densitometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58187846A JPS58187846A (en) | 1983-11-02 |
| JPH0239740B2 true JPH0239740B2 (en) | 1990-09-06 |
Family
ID=13480432
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57072131A Granted JPS58187846A (en) | 1982-04-27 | 1982-04-27 | Oxygen densitometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58187846A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005080954A1 (en) | 2004-02-20 | 2005-09-01 | Gs Yuasa Corporation | Electrochemical oxygen sensor |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5917145A (en) * | 1982-07-21 | 1984-01-28 | Japan Storage Battery Co Ltd | Galvanic cell type oxygen concentration meter |
| JPS59204754A (en) * | 1983-05-07 | 1984-11-20 | Koumiyou Rikagaku Kogyo Kk | Galvanic cell type oxygen sensor |
| JPS60100043A (en) * | 1983-11-05 | 1985-06-03 | Japan Storage Battery Co Ltd | Polarograph type oxygen densitometer |
| CN108204968B (en) * | 2018-02-08 | 2019-10-08 | 华南师范大学 | A kind of application of chip in glucose and uric acid are done while being detected |
| CN117929502A (en) * | 2018-10-17 | 2024-04-26 | 麦克赛尔株式会社 | Electrochemical oxygen sensor |
-
1982
- 1982-04-27 JP JP57072131A patent/JPS58187846A/en active Granted
Non-Patent Citations (1)
| Title |
|---|
| THE CHEMICAL ENGINEER=1972 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005080954A1 (en) | 2004-02-20 | 2005-09-01 | Gs Yuasa Corporation | Electrochemical oxygen sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58187846A (en) | 1983-11-02 |
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