JP5416501B2 - Water quality measuring device - Google Patents
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本発明は、例えば水道水などの被測定液中に含まれる残留塩素等の所定成分の濃度を測定する水質測定装置に関するものである。 The present invention relates to a water quality measuring device that measures the concentration of a predetermined component such as residual chlorine contained in a measured liquid such as tap water.
この種の水質測定装置としては、例えば特許文献１に示すように、被測定液中に浸漬した作用極及び対極間に電圧を印加して、それら電極間を流れる電流により被測定液中の残留塩素濃度を測定するものがある。作用極としては金（Ａｕ）電極又は白金（Ｐｔ）電極が用いられ、対極としては銀／塩化銀（Ａｇ／ＡｇＣｌ）電極が用いられている。 As this type of water quality measuring device, for example, as shown in Patent Document 1, a voltage is applied between a working electrode and a counter electrode immersed in a liquid to be measured, and the residual in the liquid to be measured by a current flowing between the electrodes. Some measure the chlorine concentration. A gold (Au) electrode or a platinum (Pt) electrode is used as the working electrode, and a silver / silver chloride (Ag / AgCl) electrode is used as the counter electrode.
そして、残留塩素の測定中、作用極においては、被測定液中の金属イオン（例えば鉄イオン）が作用極から電子を受け取り還元されて、作用極表面に金属（例えば鉄）の薄膜が形成されてしまう（金属メッキ）。このように、金属メッキされてしまうと、被測定液中の塩素が作用極に到達した際に、作用極から電子を受け取らずに、鉄から電子を受け取ることになる。このとき、鉄はプラスイオンになり、塩素は塩化物イオンになる反応が起こり、作用極及び対極の間に電流が流れず、残留塩素の濃度を測定することができないという問題がある。 During the measurement of residual chlorine, at the working electrode, metal ions (for example, iron ions) in the liquid to be measured receive and reduce electrons from the working electrode, and a thin film of metal (for example, iron) is formed on the surface of the working electrode. (Metal plating). In this way, when the metal is plated, when chlorine in the liquid to be measured reaches the working electrode, it receives electrons from iron without receiving electrons from the working electrode. At this time, there is a problem that a reaction occurs in which iron becomes a positive ion and chlorine becomes a chloride ion, current does not flow between the working electrode and the counter electrode, and the concentration of residual chlorine cannot be measured.
そこで、作用極から金属メッキを除去するための洗浄方法として、例えば、作用極及び対極の電源を逆接続することによって、作用極を陽極、対極を陰極として、作用極に被膜した金属を溶解除去することが考えられる。 Therefore, as a cleaning method for removing the metal plating from the working electrode, for example, by reversely connecting the working electrode and the counter electrode power supply, the working electrode is used as the anode and the counter electrode as the cathode, and the metal coated on the working electrode is dissolved and removed. It is possible to do.
しかしながら、この方法では、対極の銀／塩化銀電極において、塩化銀が銀に還元されてしまい感度が大きく変化してしまうという問題がある。また、作用極においても金又は白金等の金属を用いた電極であれば、金属メッキと作用極間の結合が強く印加電圧を大きくする必要があるだけでなく、金属メッキを除去しにくいという問題がある。 However, this method has a problem that silver chloride is reduced to silver at the counter silver / silver chloride electrode, and the sensitivity greatly changes. Further, if the working electrode is an electrode using a metal such as gold or platinum, not only is the coupling between the metal plating and the working electrode strong and it is necessary to increase the applied voltage, but it is also difficult to remove the metal plating. There is.
また、特許文献２に示すように、対極となる第一の電極、作用極となる第二の電極及び第三の電極を有する残留塩素センサが考えられている。この残留塩素センサは、測定時は、第一の電極及び第二の電極を接続して電圧を印加することにより残留塩素を測定する。一方、被測定時においては、第二の電極及び第三の電極を接続して、第二の電極を陽極、第三の電極を陰極とするものである。 Further, as shown in Patent Document 2, a residual chlorine sensor having a first electrode as a counter electrode, a second electrode as a working electrode, and a third electrode is considered. At the time of measurement, the residual chlorine sensor measures residual chlorine by connecting a first electrode and a second electrode and applying a voltage. On the other hand, at the time of measurement, the second electrode and the third electrode are connected, and the second electrode is an anode and the third electrode is a cathode.
しかしながら、この残留塩素センサは、被測定時において作用極となる第二の電極への汚れの付着を防止するものであり、第二の電極に既に付着した金属メッキ等の汚れを除去するものではない。仮に、第二の電極に付着した金属メッキを除去するとしても、第二の電極が金属製の電極（具体的には白金電極）であり、電気化学洗浄を必要以上に行うと、金属メッキを溶かす以上に作用極自体も酸化して簡単に溶けてしまうという問題がある。 However, this residual chlorine sensor is intended to prevent dirt from adhering to the second electrode, which is the working electrode at the time of measurement, and to remove dirt such as metal plating already attached to the second electrode. Absent. Even if the metal plating attached to the second electrode is removed, the second electrode is a metal electrode (specifically, a platinum electrode). There is a problem that the working electrode itself is oxidized and easily melted more than it is melted.
さらに、上記特許文献１に示すように、セラミックビーズ等の研磨材のみを単独で用いて作用極に被膜された金属メッキを除去する方法も考えられている。 Furthermore, as shown in the above-mentioned patent document 1, a method of removing metal plating coated on the working electrode using only an abrasive such as ceramic beads is also considered.
しかしながら、金属メッキを除去することができるものの、作用極自体を研磨してしまい、作用極の消耗が速くなってしまうという問題がある。 However, although the metal plating can be removed, there is a problem that the working electrode itself is polished and the working electrode is consumed quickly.
そこで本発明は、上記問題点を一挙に解決するためになされたものであり、銀／塩化銀電極からなる対極の塩化銀を消耗することなく、作用極に形成された金属メッキなどの付着物を物理的にも電気化学的にも容易に除去可能にするとともに、作用極の洗浄に対する耐久性を向上させることをその主たる所期課題とするものである。 Therefore, the present invention has been made to solve the above problems all at once, and deposits such as metal plating formed on the working electrode without consuming the silver chloride of the counter electrode composed of the silver / silver chloride electrode. The main objective is to make it easy to remove the material both physically and electrochemically and to improve the durability of the working electrode with respect to cleaning.
すなわち本発明に係る水質測定装置は、被測定液中に浸漬した作用極及び対極間に電圧を印加して、それら電極間を流れる電流により被測定液中の所定成分濃度を測定する水質測定装置であって、前記作用極となるカーボン電極と、前記対極となる銀／塩化銀電極と、前記カーボン電極との間で電圧が印加され、前記カーボン電極を電気化学洗浄するための洗浄極と、前記カーボン電極に電源の負極を接続し、前記銀／塩化銀電極に電源の正極を接続した測定状態と、前記カーボン電極に電源の正極を接続し、前記洗浄極に電源の負極を接続した洗浄状態とを切り替える切替機構と、を備えていることを特徴とする。 That is, the water quality measurement apparatus according to the present invention applies a voltage between the working electrode and the counter electrode immersed in the liquid to be measured, and measures the concentration of a predetermined component in the liquid to be measured by a current flowing between the electrodes. A voltage is applied between the carbon electrode serving as the working electrode, the silver / silver chloride electrode serving as the counter electrode, and the carbon electrode, and a cleaning electrode for electrochemically cleaning the carbon electrode; Measurement state in which the negative electrode of the power source is connected to the carbon electrode, the positive electrode of the power source is connected to the silver / silver chloride electrode, and the cleaning in which the positive electrode of the power source is connected to the carbon electrode and the negative electrode of the power source is connected to the cleaning electrode And a switching mechanism for switching between states.
このようなものであれば、切替機構によってカーボン電極に電源の正極を接続し、前記洗浄極に電源の負極を接続した洗浄状態として、カーボン電極の洗浄時において銀／塩化銀電極に電圧を印加することがない。したがって、銀／塩化銀電極の塩化銀を消耗することなく、カーボン電極表面に形成された金属メッキを電気化学洗浄により除去することができる。ここで、金属製の作用極表面と金属メッキとの結合に比べて、カーボン電極表面と金属メッキとの結合が弱いことから、電気化学洗浄だけでなく、物理的な洗浄（例えば研磨洗浄）によっても金属メッキを除去し易くすることができる。また、作用極にカーボン電極を用いることにより、従来の金属製の作用極と同程度の性能を確保しながらも電気化学洗浄に対する強度を増すことができ、作用極の長寿命化を実現することができる。 If this is the case, a switching mechanism is used to connect the positive electrode of the power supply to the carbon electrode and connect the negative electrode of the power supply to the cleaning electrode, so that a voltage is applied to the silver / silver chloride electrode when cleaning the carbon electrode. There is nothing to do. Therefore, the metal plating formed on the surface of the carbon electrode can be removed by electrochemical cleaning without consuming the silver chloride of the silver / silver chloride electrode. Here, since the bond between the carbon electrode surface and the metal plating is weaker than the bond between the metal working electrode surface and the metal plating, not only electrochemical cleaning but also physical cleaning (for example, polishing cleaning). Also, the metal plating can be easily removed. In addition, by using a carbon electrode for the working electrode, it is possible to increase the strength against electrochemical cleaning while ensuring the same level of performance as a conventional metal working electrode, and to realize a longer working electrode life. Can do.
水質測定装置の具体的な構成としては、前記被測定液を流通させる流路が形成されたフローチャンバに前記銀／塩化銀電極、前記カーボン電極、及び前記洗浄極が設けられており、前記流路において、前記銀／塩化銀電極の上流側に前記カーボン電極が設けられていることが望ましい。このように銀／塩化銀電極及びカーボン電極を配置することにより、銀／塩化銀電極から溶け出した銀イオンがカーボン電極に到達しにくくすることができ、カーボン電極の表面に銀がメッキされることを防止することができる。 As a specific configuration of the water quality measuring apparatus, the silver / silver chloride electrode, the carbon electrode, and the cleaning electrode are provided in a flow chamber in which a flow path for circulating the liquid to be measured is formed. In the road, the carbon electrode is preferably provided upstream of the silver / silver chloride electrode. By arranging the silver / silver chloride electrode and the carbon electrode in this way, silver ions dissolved from the silver / silver chloride electrode can be made difficult to reach the carbon electrode, and silver is plated on the surface of the carbon electrode. This can be prevented.
より具体的には、前記被測定液を流通させる流路が形成されたフローチャンバに前記銀／塩化銀電極、前記カーボン電極、及び前記洗浄極が設けられており、前記フローチャンバ内の流路に前記被測定液の流れに伴って移動する電極研磨材が設けられ、前記作用極が、前記流路内において前記電極研磨材に当たる位置に設けられ、前記対極が、前記流路内において前記電極研磨材に当たらない位置に設けられていることが望ましい。これならば、洗浄時だけでなく、測定時においてもカーボン電極の付着物を除去することができる。このとき、作用極がカーボン電極であり、電極表面と金属メッキとの結合が弱いことから、電極研磨材を当てることによって電極表面から容易に金属メッキを除去することができる。また、電極研磨材が対極に当たらないように構成しているので、研磨による対極の消耗を防ぐことができる。 More specifically, the silver / silver chloride electrode, the carbon electrode, and the cleaning electrode are provided in a flow chamber in which a flow path for flowing the measurement liquid is formed, and the flow path in the flow chamber An electrode abrasive that moves with the flow of the liquid to be measured is provided, the working electrode is provided in a position that contacts the electrode abrasive in the flow path, and the counter electrode is provided in the flow path. It is desirable to be provided at a position where it does not hit the abrasive. In this case, the carbon electrode deposits can be removed not only during cleaning but also during measurement. At this time, since the working electrode is a carbon electrode and the bond between the electrode surface and the metal plating is weak, the metal plating can be easily removed from the electrode surface by applying an electrode abrasive. In addition, since the electrode abrasive is configured not to hit the counter electrode, it is possible to prevent consumption of the counter electrode due to polishing.
前記各電極が、前記フローチャンバにおいて独立して交換可能に配置されていることが望ましい。これならば、各電極を独立してフローチャンバに取り付けることができ、フローチャンバ内への適切な配置が可能となる。また、消耗又は故障などして交換する必要がある電極のみを交換すれば良いので、ランニングコストを低減することができる。 It is desirable that the electrodes are arranged independently and interchangeably in the flow chamber. If this is the case, each electrode can be independently attached to the flow chamber, and appropriate arrangement in the flow chamber becomes possible. In addition, since only the electrodes that need to be replaced due to wear or failure need to be replaced, the running cost can be reduced.
このように構成した本発明によれば、銀／塩化銀電極からなる対極の塩化銀を消耗することなく、作用極に形成された金属メッキなどの付着物を物理的にも電気化学的にも容易に除去可能にするとともに、作用極の洗浄に対する耐久性を向上させることができる。 According to the present invention configured as described above, deposits such as metal plating formed on the working electrode can be physically and electrochemically consumed without consuming the silver chloride of the counter electrode composed of the silver / silver chloride electrode. While being able to remove easily, durability with respect to washing | cleaning of a working electrode can be improved.
以下に本発明に係る水質測定装置の一実施形態について図面を参照して説明する。 An embodiment of a water quality measuring apparatus according to the present invention will be described below with reference to the drawings.
本実施形態に係る水質測定装置１００は、例えば水道水などの被測定液中に浸漬した作用極及び対極間に電圧を印加して、それら電極間を流れる電流により被測定液中の残留塩素濃度を測定する残留塩素測定装置であり、図１に示すように、作用極となるカーボン電極２と、対極となる銀／塩化銀電極３と、カーボン電極２との間で電圧が印加され、カーボン電極２を電気化学洗浄するための洗浄極４と、カーボン電極２及び銀／塩化銀電極３に測定電圧を印加する測定状態とカーボン電極２及び洗浄極４に洗浄電圧を印加する洗浄状態とを切り替える切替機構６とを備えている。なお、残留塩素測定装置１００は、図１においては図示しないが、銀／塩化銀電極からなる比較極５を有し、作用極２の比較極５に対する電位を、設定した一定値に保つように構成されている。 The water quality measurement apparatus 100 according to the present embodiment applies a voltage between a working electrode and a counter electrode immersed in a liquid to be measured such as tap water, and the residual chlorine concentration in the liquid to be measured by a current flowing between the electrodes. As shown in FIG. 1, a voltage is applied between the carbon electrode 2 serving as the working electrode, the silver / silver chloride electrode 3 serving as the counter electrode, and the carbon electrode 2, as shown in FIG. A cleaning electrode 4 for electrochemically cleaning the electrode 2, a measurement state in which a measurement voltage is applied to the carbon electrode 2 and the silver / silver chloride electrode 3, and a cleaning state in which a cleaning voltage is applied to the carbon electrode 2 and the cleaning electrode 4. And a switching mechanism 6 for switching. Although not shown in FIG. 1, the residual chlorine measuring device 100 has a comparison electrode 5 made of a silver / silver chloride electrode so that the potential of the working electrode 2 with respect to the comparison electrode 5 is kept at a set constant value. It is configured.
カーボン電極２は、固体状の水不透過性及び導電性を有するカーボンからなる電極であり、例えば、グラッシーカーボン、ダイアモンドライクカーボン（ＤＬＣ）、例えばホウ素等をドープして導電性を持たせたダイアモンド、グラファイトとカーボンの複合材料であるプラスチックフォームドカーボン（ＰＦＣ）を用いて構成されている。 The carbon electrode 2 is an electrode made of solid water-impermeable and conductive carbon. For example, glassy carbon, diamond-like carbon (DLC), such as diamond doped with boron or the like, is made conductive. In addition, it is made of plastic-formed carbon (PFC) which is a composite material of graphite and carbon.
洗浄極４は、作用極２と同様に、カーボン電極である。これにより、洗浄時において洗浄極４に形成された金属メッキを容易に除去することができるだけでなく、洗浄極４を長寿命化することができ、長期的に安定した測定、洗浄が可能となる。 The cleaning electrode 4 is a carbon electrode like the working electrode 2. As a result, not only can the metal plating formed on the cleaning electrode 4 be easily removed during cleaning, but the service life of the cleaning electrode 4 can be extended, and stable measurement and cleaning can be performed over a long period of time. .
切替機構６は、カーボン電極２（作用極）に電源の負極を接続し、銀／塩化銀電極３（対極）に電源の正極を接続して、作用極２及び対極３間に電流を流す測定状態と、カーボン電極２（作用極）に電源の正極を接続し、洗浄極４に電源の負極を接続して、作用極２を電気化学洗浄する洗浄状態と、を切り替えるものである。 The switching mechanism 6 is a measurement in which the negative electrode of the power source is connected to the carbon electrode 2 (working electrode), the positive electrode of the power source is connected to the silver / silver chloride electrode 3 (counter electrode), and a current flows between the working electrode 2 and the counter electrode 3. The state is switched between a cleaning state in which the positive electrode of the power source is connected to the carbon electrode 2 (working electrode) and the negative electrode of the power source is connected to the cleaning electrode 4 to electrochemically clean the working electrode 2.
具体的な構成は、作用極２及び対極３を接続する第１の回路上７に設けられた第１のスイッチ６１と、作用極２及び洗浄極４を接続する第２の回路上８に設けられた第２のスイッチ６２とからなる。なお、第１の回路上６１には、測定時において作用極２及び対極３に測定電圧を印加するための測定用電源９及び当該回路上を流れる電流を検出する電流検出部１０が設けられている。この測定用電源９及び電流検出部１０はポテンシオスタットの一部である。また、第２の回路上８には、洗浄時において作用極２及び洗浄極４に洗浄電圧を印加するための洗浄用電源１１が接続されている。なお、本実施形態では、測定用電源９及び洗浄用電源１１を分けて設けているが、１つの電源で測定電圧及び洗浄電圧をそれぞれの電極に印加するように回路構成しても良い。 Specifically, the first switch 61 provided on the first circuit 7 that connects the working electrode 2 and the counter electrode 3 and the second circuit 8 that connects the working electrode 2 and the cleaning electrode 4 are provided. The second switch 62 is provided. The first circuit 61 is provided with a measurement power source 9 for applying a measurement voltage to the working electrode 2 and the counter electrode 3 at the time of measurement, and a current detection unit 10 for detecting a current flowing on the circuit. Yes. The measurement power supply 9 and the current detection unit 10 are part of a potentiostat. Further, a cleaning power source 11 for applying a cleaning voltage to the working electrode 2 and the cleaning electrode 4 at the time of cleaning is connected to the second circuit 8. In the present embodiment, the measurement power source 9 and the cleaning power source 11 are provided separately, but a circuit configuration may be adopted in which the measurement voltage and the cleaning voltage are applied to the respective electrodes with a single power source.
本実施形態では、測定用電源９により作用極２に印加する測定電位は一定であり、その測定電位は比較極５に対して−０．３〜−０．５Ｖである。また、洗浄用電源１１による作用極２に対する洗浄極４の洗浄電位は−２．５〜−５．０Ｖである。この洗浄電位は断続的に印加するようにしている。例えば、周波数約１０Ｈｚで印加する。これにより、作用極２に付着している付着物（具体的には金属メッキ）は印加直後に素早く溶解し、作用極２周囲の水等の電気分解が生じることを防ぐことができる。 In this embodiment, the measurement potential applied to the working electrode 2 by the measurement power source 9 is constant, and the measurement potential is −0.3 to −0.5 V with respect to the comparison electrode 5. Further, the cleaning potential of the cleaning electrode 4 with respect to the working electrode 2 by the cleaning power supply 11 is −2.5 to −5.0V. This cleaning potential is applied intermittently. For example, it is applied at a frequency of about 10 Hz. Thereby, the deposit | attachment (specifically metal plating) adhering to the working electrode 2 melt | dissolves quickly immediately after application, and it can prevent that electrolysis of the water etc. around the working electrode 2 arises.
そして、測定時においては、第１のスイッチ６１を閉じ、第２のスイッチ６２を開けることにより、作用極２及び対極３に測定電圧が印加されて両極２、３間に電流が流れ測定状態が形成される。一方、第１のスイッチ６１を開け、第２のスイッチ６２を閉じることにより作用極２及び洗浄極４に洗浄電極が印加されて両極２、４間に電流が流れ洗浄状態が形成される。なお、このとき作用極２においては、Ｘ→Ｘ＋＋ｅ−の反応が生じる。なおＸは金属を示す。これにより、洗浄状態において作用極２表面に被膜された金属を溶解させることができる。 At the time of measurement, by closing the first switch 61 and opening the second switch 62, a measurement voltage is applied to the working electrode 2 and the counter electrode 3, and a current flows between both the electrodes 2 and 3, and the measurement state is established. It is formed. On the other hand, by opening the first switch 61 and closing the second switch 62, the cleaning electrode is applied to the working electrode 2 and the cleaning electrode 4, and a current flows between both the electrodes 2, 4 to form a cleaning state. At this time, a reaction of X → X + + e − occurs at the working electrode 2. X represents a metal. Thereby, the metal coated on the surface of the working electrode 2 can be dissolved in the cleaning state.
しかして本実施形態の水質測定装置１００は、被測定液を流通させる流路Ｌが形成されたフローチャンバＦＣを有し、当該フローチャンバＦＣに作用極２、対極３、比較極５、及び洗浄極４が設けられている。 Therefore, the water quality measurement apparatus 100 of the present embodiment has a flow chamber FC in which a flow path L through which a liquid to be measured is circulated is formed. The working electrode 2, the counter electrode 3, the comparison electrode 5, and the cleaning are provided in the flow chamber FC. A pole 4 is provided.
このフローチャンバＦＣは、図２に示すように、上部に接続された導入ポートＰ１と、当該導入ポートＰ１に対向して上部に設けられた導出ポートＰ２と、内部に導入ポートＰ１及び導出ポートＰ２を連通する流路Ｌが形成されたチャンバ本体ＦＣ１と、を備えている。なお、流路Ｌを流れる被測定液の流量は例えば５００〜１５００ｃｃ／ｍｉｎである。 As shown in FIG. 2, the flow chamber FC includes an introduction port P1 connected to the upper part, a derivation port P2 provided at the upper part facing the introduction port P1, and an introduction port P1 and an derivation port P2 inside. And a chamber main body FC1 in which a flow path L communicating therewith is formed. The flow rate of the liquid to be measured flowing through the flow path L is, for example, 500 to 1500 cc / min.
流路Ｌは、上下方向に延設されており、その下部には、セラミックビーズ等の電極研磨材１２が収容される研磨材収容部Ｌ１が形成されている。また、研磨材収容部Ｌ１を形成するチャンバ本体ＦＣ１の底部は分離可能であり、電極研磨材１２を交換可能に構成している。この流路Ｌにおいて、導入ポートＰ１から流路Ｌに導入された被測定液は、下方に向かって流れ、研磨材収容部Ｌ１で折り返して、上方に向かって流れ、導出ポートＰ２から導出される。 The flow path L is extended in the up-down direction, and an abrasive material accommodating portion L1 for accommodating the electrode abrasive material 12 such as ceramic beads is formed in the lower part thereof. Further, the bottom of the chamber main body FC1 that forms the abrasive accommodating portion L1 can be separated, and the electrode abrasive 12 can be replaced. In this flow path L, the liquid to be measured introduced into the flow path L from the introduction port P1 flows downward, turns back at the abrasive material storage portion L1, flows upward, and is led out from the lead-out port P2. .
また、導入ポートＰ１には、導入された被測定液を研磨材収容部Ｌ１に案内するための内部配管１３が接続されている。これにより、導入ポートＰ１から導入された被測定液は、内部配管１３を通って電極研磨材１２に当たり易くし、それにより電極研磨材１２が舞い上がるように構成している。 The introduction port P1 is connected to an internal pipe 13 for guiding the introduced liquid to be measured to the abrasive accommodating part L1. As a result, the liquid to be measured introduced from the introduction port P <b> 1 is easy to hit the electrode abrasive 12 through the internal pipe 13, and thereby the electrode abrasive 12 is soared.
そして少なくとも作用極２、比較極５及び対極３は、流路Ｌにおける被測定液の流れ方向（図２中の矢印Ａ）に沿って、上流側から作用極２、比較極５及び対極３の順で配置されている。 At least the working electrode 2, the comparison electrode 5, and the counter electrode 3 are arranged so that the working electrode 2, the comparison electrode 5, and the counter electrode 3 are arranged from the upstream side along the flow direction (arrow A in FIG. Arranged in order.
より詳細には、作用極２は研磨材収容部Ｌ１内部又はその近傍において、被測定液の流れ方向に対して対向するように配置される。つまり、作用極２は、被測定液の流れに伴って移動する電極研磨材１２が当たる位置に配置されている。これにより、被測定液の流れによって舞い上がった電極研磨材１２が作用極２に当たり、作用極２表面の付着物が除去される。このとき、作用極２がカーボン電極２により構成されていることから、電極研磨材１２の接触により付着物が除去され易い。また、作用極２に対して斜めから電極研磨材１２が当たるように配置して、作用極２表面の摩耗を可及的に小さくしている。なお、図２において作用極２は、作用極ホルダ１４の先端部に交換可能に取り付けられたチップ状をなすものである。作用極ホルダ１４は、チャンバ本体ＦＣ１の側壁に脱着可能に取り付けられる。 More specifically, the working electrode 2 is disposed inside or near the abrasive container L1 so as to oppose the flow direction of the liquid to be measured. That is, the working electrode 2 is disposed at a position where the electrode abrasive 12 that moves with the flow of the liquid to be measured hits. As a result, the electrode abrasive 12 that has been swollen by the flow of the liquid to be measured hits the working electrode 2 and the deposits on the surface of the working electrode 2 are removed. At this time, since the working electrode 2 is composed of the carbon electrode 2, deposits are easily removed by contact with the electrode abrasive 12. Moreover, it arrange | positions so that the electrode abrasive | polishing material 12 may strike diagonally with respect to the working electrode 2, and the abrasion of the working electrode 2 surface is made as small as possible. In FIG. 2, the working electrode 2 has a chip shape that is replaceably attached to the tip of the working electrode holder 14. The working electrode holder 14 is detachably attached to the side wall of the chamber body FC1.
そして、流路Ｌにおいて作用極２の下流側に比較極５及び対極３がこの順で設けられている。これにより、対極３から溶け出した銀イオンが作用極２に到達しにくくし、作用極２表面に銀がメッキされることを防止している。 A comparison electrode 5 and a counter electrode 3 are provided in this order on the downstream side of the working electrode 2 in the flow path L. This makes it difficult for the silver ions dissolved from the counter electrode 3 to reach the working electrode 2 and prevents the surface of the working electrode 2 from being plated with silver.
ここで、比較極５は作用極２に可及的に近いことが望ましいが、電極研磨材１２が当たることによる消耗を防ぐために、電極研磨材１２が当たらない限度で作用極２に近接配置している。また、対極３はこの比較極５の下流側に設けられており、電極研磨材１２が当たることによる消耗を防ぐために、電極研磨材１２が当たらない位置に配置されている。洗浄極４は流路Ｌのいずれの位置に配置しても良いが、電極研磨材１２による付着物の除去効果を得るためには電極研磨材１２が移動する範囲内、具体的には研磨材収容部Ｌ１内部又はその近傍に配置することが望ましい。 Here, it is desirable that the comparative electrode 5 be as close as possible to the working electrode 2. ing. Further, the counter electrode 3 is provided on the downstream side of the comparison electrode 5 and is disposed at a position where the electrode abrasive 12 does not contact in order to prevent wear due to the electrode abrasive 12 being applied. The cleaning electrode 4 may be disposed at any position in the flow path L. However, in order to obtain the effect of removing the deposits by the electrode abrasive 12, the electrode abrasive 12 is moved, specifically, the abrasive. It is desirable to arrange in the accommodating part L1 or its vicinity.
なお、本実施形態では、対極３、比較極５及び洗浄極４は、故障時以外に取り外し又は交換の必要がないため、背面部の収容ボックス１５に取り付けられて収容されている（図３参照）。そして、収容ボックス１５をチャンバ本体ＦＣ１から取り外すことによって、対極３、比較極５及び洗浄極４を一挙にチャンバ本体ＦＣ１から取り外すことができるように構成している。なお、対極３、比較極５又は洗浄極４それぞれは、独立して収容ボックス１５から取り外すことができ、これにより、各極３、４、５をチャンバ本体ＦＣ１から取り外すこともできる。 In the present embodiment, the counter electrode 3, the comparison electrode 5, and the cleaning electrode 4 do not need to be removed or replaced except when they are out of order, so that they are attached and accommodated in the accommodation box 15 on the back side (see FIG. 3). ). Then, by removing the storage box 15 from the chamber body FC1, the counter electrode 3, the comparison electrode 5 and the cleaning electrode 4 can be removed from the chamber body FC1 all at once. Each of the counter electrode 3, the comparison electrode 5, and the cleaning electrode 4 can be detached from the storage box 15 independently, whereby each of the electrodes 3, 4, and 5 can be detached from the chamber body FC1.
＜本実施形態の効果＞
このように構成した本実施形態に係る水質測定装置１００によれば、切替機構６によってカーボン電極２に洗浄用電源１１の正極を接続し、前記洗浄極４に電源１１の負極を接続した洗浄状態として、カーボン電極２の洗浄時において銀／塩化銀電極３に電圧を印加することがない。したがって、銀／塩化銀電極３の塩化銀を消耗することなく、カーボン電極２表面に形成された金属メッキを電気化学洗浄により除去することができる。ここで、金属製の作用極２表面と金属メッキとの結合に比べて、カーボン電極２表面と金属メッキとの結合が弱いことから、電気化学洗浄だけでなく、物理的な洗浄（例えば研磨洗浄）によっても金属メッキを除去し易くすることができる。また、作用極２にカーボン電極２を用いることにより、従来の金属製の作用極２と同程度の性能を確保しながらも電気化学洗浄に対する強度を増すことができ、作用極２の長寿命化を実現することができる。
<Effect of this embodiment>
According to the water quality measuring apparatus 100 according to the present embodiment configured as described above, a cleaning state in which the switching mechanism 6 connects the positive electrode of the cleaning power supply 11 to the carbon electrode 2 and connects the negative electrode of the power supply 11 to the cleaning electrode 4. As a result, no voltage is applied to the silver / silver chloride electrode 3 when the carbon electrode 2 is cleaned. Therefore, the metal plating formed on the surface of the carbon electrode 2 can be removed by electrochemical cleaning without consuming the silver chloride of the silver / silver chloride electrode 3. Here, since the bond between the surface of the carbon electrode 2 and the metal plating is weaker than the bond between the surface of the metal working electrode 2 and the metal plating, not only electrochemical cleaning but also physical cleaning (for example, polishing cleaning) ) Also facilitates removal of the metal plating. In addition, by using the carbon electrode 2 for the working electrode 2, the strength against electrochemical cleaning can be increased while ensuring the same level of performance as the conventional working electrode 2 made of metal, and the life of the working electrode 2 is extended. Can be realized.
なお、本発明は前記実施形態に限られるものではない。 The present invention is not limited to the above embodiment.
例えば、前記実施形態では、作用極、対極及び比較極を有するポーラログラフ法を用いた残留塩素測定装置について説明したが、比較極を有さないポーラログラフを用いたものであっても良いし、ガルバニセル法を用いた残留塩素測定装置であっても良い。 For example, in the above-described embodiment, the residual chlorine measuring device using the polarographic method having the working electrode, the counter electrode, and the reference electrode has been described. It may be a residual chlorine measuring device using
また、前記実施形態の水質測定装置としては、被測定液中の溶存酸素濃度を測定する溶存酸素測定装置であっても良い。 Further, the water quality measuring device of the embodiment may be a dissolved oxygen measuring device that measures the dissolved oxygen concentration in the liquid to be measured.
その他、本発明は前記実施形態に限られず、その趣旨を逸脱しない範囲で種々の変形が可能であるのは言うまでもない。 In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
１００・・・水質測定装置（残留塩素測定装置）
２ ・・・作用極（カーボン電極）
３ ・・・対極（銀／塩化銀電極）
４ ・・・洗浄極
６ ・・・切替機構
９ ・・・測定用電源
１１ ・・・洗浄用電源
ＦＣ ・・・フローチャンバ
Ｌ ・・・流路
１２ ・・・電極研磨材
100 ... Water quality measuring device (residual chlorine measuring device)
2 ... Working electrode (carbon electrode)
3 ... Counter electrode (silver / silver chloride electrode)
4 ... Cleaning electrode 6 ... Switching mechanism 9 ... Measurement power supply 11 ... Cleaning power supply FC ... Flow chamber L ... Flow path 12 ... Electrode polishing material
Claims (5)
前記作用極との間で電圧が印加され、前記作用極を電気化学洗浄するためのカーボン電極からなる洗浄極と、
前記作用極に電源の負極を接続し、前記対極に電源の正極を接続した測定状態と、前記作用極に電源の正極を接続し、前記洗浄極に電源の負極を接続した洗浄状態とを切り替える切替機構と、を備え、
前記被測定液を流通させる流路が形成されたフローチャンバに、前記対極、前記作用極及び前記洗浄極が設けられるとともに、前記被測定液の流れに伴って移動する電極研磨材が設けられており、
前記流路の上流側から順に前記作用極及び前記対極が配置されて、前記作用極が、前記流路内において前記電極研磨材に当たる位置に設けられており、
前記電源が、前記洗浄状態において、前記作用極に対する前記洗浄極の洗浄電位を、断続的に印加するものである被測定液測定装置。 A voltage to be measured is applied between a working electrode made of a carbon electrode immersed in the liquid to be measured and a counter electrode made of a silver / silver chloride electrode, and the concentration of a predetermined component in the liquid to be measured is measured by a current flowing between the electrodes. A liquid measuring device,
A voltage is applied between the working electrode and a cleaning electrode comprising a carbon electrode for electrochemically cleaning the working electrode;
Switching between a measurement state in which the negative electrode of the power source is connected to the working electrode and a positive electrode of the power source is connected to the counter electrode, and a cleaning state in which the positive electrode of the power source is connected to the working electrode and the negative electrode of the power source is connected to the cleaning electrode A switching mechanism,
The counter chamber, the working electrode, and the cleaning electrode are provided in a flow chamber in which a flow path for flowing the liquid to be measured is formed, and an electrode abrasive that moves along with the flow of the liquid to be measured is provided. And
The working electrode and the counter electrode are arranged in order from the upstream side of the flow path, and the working electrode is provided at a position in the flow path that contacts the electrode abrasive,
The power supply is, in the above cleaning state, the cleaning potential of the cleaning electrode with respect to the working electrode, test liquid measurement device is shall be intermittently applied.
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