WO2015026104A1

WO2015026104A1 - Hydrogen ion electrode composed of composite material of nano iridium oxide and polymer resin and enabling surface regeneration, ph sensor using same, and method for manufacturing same

Info

Publication number: WO2015026104A1
Application number: PCT/KR2014/007578
Authority: WO
Inventors: 박종만; 김문희
Original assignee: 주식회사 이지센싱
Priority date: 2013-08-20
Filing date: 2014-08-14
Publication date: 2015-02-26

Abstract

Provided are a hydrogen ion electrode composed of a composite material of polymer resin and nano iridium oxide, the composite material containing 1-10 nm sized nano iridium oxide particles and/or aggregates thereof which are dispersed to be electrically connected to each other in a moldable, thermoplastic, and hydrophobic polymer resin matrix; a pH sensor using the same; and a method for manufacturing the same. The surface of the hydrogen ion electrode shows very fast pH sensitivity when exposed to a sample solution, and the pH sensitivity is approximate to biphasic characteristics. Furthermore, regardless of high reproducibility of pH sensitivity, abrupt pH change, and repetitive use, very low hysteria, durability due to high physical strength, and high surface regeneration due to polishing are exhibited, and thus, the lifetime of the electrode can be extended and various sizes and shapes of electrodes can be easily manufactured.

Description

Surface reproducible hydrogen ion electrode composed of composite material of nano iridium oxide and polymer resin, PH sensor using same and method for manufacturing same

The present specification relates to a hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin and capable of surface regeneration by surface polishing, a pH sensor using the same, and a method of manufacturing the same.

PH is used as one of basic analysis items in various fields such as environment, food, medicine and medicine, and a pH sensor is used to measure this.

Conventionally, a pH selective glass film electrode has been used as a pH sensor. However, this electrode is fragile and difficult to activate when fouling.

That is, for example, if the sensor is exposed to environmental samples in the long term, such as for long term water quality monitoring systems, or if the properties of the sample itself can seriously cause surface contamination of the sensor, such as in soil analysis, food processing, etc. There is a problem of serious fouling, as well as the problem of deactivation of the pH sensor. Accordingly, there is a problem that the sensor must be replaced or activated periodically.

Metal oxide films formed on the metal electrode surface can be used for hydrogen ion concentration measurement because the redox potential of these oxides depends on the hydrogen ion concentration. Such metal oxides include TiO ₂ , RuO ₂ , RhO ₂ , SnO ₂ , Ta ₂ O ₅ , OsO ₂ , PdO ₂ , PtO ₂ or IrO ₂ (Non-Patent Document 1).

In hydrogen ion selective electrodes utilizing metal oxides, the reversible redox potential of the metal oxide is mostly dependent on the hydrogen ion concentration. The sputtering method, high temperature pyrolysis method, electrochemical oxidation method of metal wire, etc. are applied to manufacture these metal oxide film pH electrodes.

Typical electrochemical techniques include iridium (Ir) metal electrodes immersed in sulfuric acid solution, for example, oxidizing the electrode's iridium to iridium (IV) oxide while traversing the electrode potential between -0.25V and + 1.25V (vs. SCE). It's the way to go. Iridium oxide formed on the surface of the metal electrode is a hydrated iridium oxide, IrO ₂ · 4H ₂ O, Ir (OH) ₄ · 2H ₂ O, [IrO ₂ (OH) ₂ · 2H ₂ O] ^2- and the like. It is known to exhibit super-Nerntian responsiveness of about -90 dB / pH unit (Non-Patent Document 2).

In the case of the iridium oxide film electrode manufactured by sputtering or pyrolysis method on the surface of platinum, iridium, or a conductive metal electrode, it is known that the surface iridium oxide is anhydrous iridium oxide. A sensitivity of about −59 μs / pH is shown (Non-Patent Document 3).

In the case of the iridium oxide coating film electrode manufactured by the above sputtering or pyrolysis method, since the iridium oxide coating film is formed under a high temperature or high vacuum environment, microscopic uniformity of the coating film and micropores formed during pyrolysis exist to penetrate the solution. There is a problem that the time is long and as a result the delayed response speed is shown.

In addition, it is difficult to perform a complete exchange of the solution quickly when the measurement solution is exchanged, there is a problem such as a delay in the response time as well as a lack of reproducibility, and also shows a problem that greatly deviates from the theoretical response slope (-59.2mV / pH). In addition, when the surface is contaminated or the sensitivity of the electrode is lowered, it is difficult to take effective measures for regeneration of the electrode characteristics, thereby reducing the electrode life.

Recently, a modified glass or ceramic composite electrode has been disclosed, in which a conductive metal fine particle mixture is mixed with glass or ceramic powder, molded and sintered at high temperature (Non-Patent Document 4, Patent Document 1).

However, according to the research results of the present inventors, the above technique has a problem that the responsiveness of the electrode signal and the long time required for the surface equilibrium are slow, and the hysteresis of the rapid pH change is large. Since it is a method of mixing the ceramic powder and molding it and sintering at high temperature, manufacturing is difficult.

On the other hand, the hydrogen ion electrode which couple | bonded carbon black and micro iridium oxide particle | grains with the binder polymer resin was published (nonpatent literature 5).

However, according to the research results of the present inventors, the hydrogen ion electrode is superior in physical stability and surface reproducibility as compared to the conventional glass electrode or polymer membrane electrode, but the manufacturing process is complicated by the addition of carbon black as a conductor. In addition, there is a problem in that the pH dependence of the polymer electrode for each lot produced a severe deviation in the range of 50 ~ 60 mV / pH depending on the electrode. In addition, there is a problem in that it shows a relatively high hysteresis of about 5 mV with respect to a sudden (large) pH change, and the measured pH due to repeated use shows a large error of about 0.1 pH unit.

[Preceding technical literature]

[Patent Documents]

(Patent Document 1): Korean Patent No. 776981

[Non-Patent Documents]

(Non-Patent Document 1): A. Fog, R. P. Buck, Sensors and Actuators, 1984, 5, 137-146

(Non-Patent Document 2): D. Midgly, Talanta, 1990, 37, 767-781

(Non-Patent Document 3): P. Van Hooudt, Z. Lewandowski, B. Little, Biotech. Bioeng. 1992, 40, 601-608

(Non-Patent Document 4): J. Park, J. Kim, H. Quan, Microchem. J. 2010, 95, 102-106

(Non-Patent Document 5): H. Quan, W. Kim, K.-C. Chung, J. Park, Bull. Korean Chem. Soc. 2005, 26, 1565-1568.

In exemplary embodiments of the present invention, in one aspect, the nano iridium particles on the surface of the electrode exposed to the solution as a pH electrode using the electrical conductivity of the nano-iridium oxide itself contained in the composite electrode without the help of carbon black as a conductor Not only is the pH response very fast and close to ideal (the pH dependence close to the theoretical value (-59.2 kW / pH)), the high reproducibility of the pH sensitivity, very low despite rapid (large) pH changes and repeated use A hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin exhibiting hysteresis, durability according to high physical strength, and high surface regeneration by polishing is provided.

In exemplary embodiments of the present invention, in another aspect, it is also provided to provide a pH sensor comprising the hydrogen ion electrode.

In another aspect of the present invention, in another aspect, to provide a method for producing the above-described hydrogen ion electrode in a very simple manufacturing process, unlike conventional complex manufacturing methods.

In exemplary embodiments of the present invention, in the moldable thermoplastic and hydrophobic polymer resin matrix, nano-iridium oxide particles having a size of 1 to 10 nm are in an individual particle state, or in an aggregate state in which the particles are aggregated, or in the individual particles and aggregates. Is a hydrogen ion electrode dispersed in a mixed state, wherein the nano iridium oxide particles are electrically connected in a matrix to enable surface regeneration of a composite material of nano iridium oxide and a polymer resin, which enables electrical conduction of the hydrogen ion electrode. It provides a hydrogen ion electrode.

In an exemplary embodiment, the nano iridium oxide particles of 1 to 10nm size are dispersed in individual particle states, and the individual particles are electrically connected to enable electric conduction of the hydrogen ion electrode.

In an exemplary embodiment, the nano iridium oxide particles of the 1 ~ 10nm size are dispersed in the aggregated aggregate state, the aggregates of the nano iridium oxide particles are electrically connected to enable the electrical conduction of the hydrogen ion electrode.

In an exemplary embodiment, the nano iridium oxide particles having a size of 1 to 10 nm are dispersed in a mixture of individual particle states and aggregated states, and the nano iridium oxide particles or aggregates are electrically connected in a matrix to form hydrogen ions. Enables electrical conduction of the electrode.

In an exemplary embodiment, the hydrogen ion electrode is made of 20 to 45% by weight of the nano iridium oxide particles and 80% to 55% by weight of the polymer resin.

In an exemplary embodiment, the hydrogen ion electrode may exhibit a hysteresis voltage of 1 to 2 mV due to a sharp (wide) pH change that increases the pH from 3 to 11 and then drops back to 3.

In an exemplary embodiment, the polymer resin may be a polymer resin or a polymer resin mixture having a glass transition temperature (T _g ) of 20 ° C. or more.

Exemplary embodiments of the invention also provide a pH sensor comprising a non-electrically conductive housing, the hydrogen ion electrode located within the housing and electrical contact means connected to the hydrogen ion electrode.

In one exemplary embodiment, the housing is a cylindrical housing, there is an open portion on one side of the cylindrical housing to expose the electrode sensitive portion to the outside, the electrical contact means on the other side of the cylindrical housing It is connected to the outside of the housing.

In exemplary embodiments of the present invention, a method of manufacturing the hydrogen ion electrode also includes a moldable thermoplastic and hydrophobic polymer resin, a group consisting of nano iridium oxide particles having a size of 1 to 10 nm and aggregates in which the nano iridium oxide particles are aggregated. Preparing a mixed solution of at least one and a water-soluble organic solvent selected from;

Adding water to the mixed solution and removing a water-soluble organic solvent to obtain a composite material of a polymer resin and a nano iridium oxide; And

It provides a method for producing a hydrogen ion electrode comprising a composite material of nano iridium oxide and a polymer resin, characterized in that it comprises a step of manufacturing a hydrogen ion electrode by heating the composite material.

In an exemplary embodiment, the manufacturing method further includes preparing the nano iridium oxide particles and / or aggregates, and using the nano iridium oxide particles and / or aggregates in a state of being dispersed in a water-soluble organic solvent. do.

In an exemplary embodiment, in the preparing method, in the preparing a mixed solution, the polymer resin is dissolved in a water-soluble organic solvent to prepare a mixed solution, and then the nano iridium oxide particles and / or aggregates are added to the mixed solution. Can be mixed and dispersed.

In an exemplary embodiment, in the preparing method, in the preparing a mixed solution, the nano iridium oxide particles and / or aggregates are mixed with a water-soluble organic solvent and dispersed to prepare a mixed solution, and then the polymer resin is mixed with the mixed solution. The solution can be mixed and dispersed.

In an exemplary embodiment, in the preparation method, in the preparing a mixed solution, the polymer resin is dissolved in a water-soluble organic solvent to prepare a first mixed solution, and the nano iridium oxide particles and / or aggregates are water-soluble organic solvents. And a second mixed solution may be prepared by mixing and dispersing, and the first mixed solution and the second mixed solution may be mixed and dispersed.

In an exemplary embodiment, the polymer resin used in the production method is a moldable thermoplastic and hydrophobic polymer resin or polymer resin mixture having a glass transition temperature of 20 ° C. or higher, such as PMMA (polymethyl methacrylate) resin, PVC (Polyvinylchloride) resins or ABS (acrylonitrile butadiene styrene) resins or mixtures thereof.

In an exemplary embodiment, the water-soluble organic solvent used in the preparation method may be acetone, THF (tetrahydrofuran), DMF (dimethylformamide) or DMSO (dimethylsulfoxide).

In an exemplary embodiment, in the manufacturing method, the composite material may be pulverized to form a powder and then heat-molded.

In an exemplary embodiment, the manufacturing method may polish the surface of the prepared hydrogen ion electrode.

In an exemplary embodiment, in the preparation method, the surface of the prepared hydrogen ion electrode may be polished and stabilized in water (eg, deionized water).

In an exemplary embodiment, the manufacturing method may further comprise coupling the heat-formed hydrogen ion electrode into a non-electrically conductive housing and connecting electrical contact means to the hydrogen ion electrode.

The hydrogen ion electrode according to exemplary embodiments of the present invention not only makes the pH sensitization of nano iridium particles on the electrode surface exposed to the measurement sample solution very fast and close to ideal [theoretical value (-59.2 dl / pH) Close pH dependence (eg -59.6 or -59.7 mV / pH, correlation coefficient greater than 0.9999), high reproducibility (eg, 0.4-0.5% relative error), excellent surface reproducibility (eg, 0.4-0.5% relative error) Surface regeneration) and can exhibit very low hysteresis of 1-2 mV despite rapid (large) pH changes and repeated use.

In addition, since the hydrogen ion electrode according to the exemplary embodiments of the present invention not only exhibits durability according to high physical strength, but also exhibits high surface regeneration as described above, the electrode surface reproducible by simple polishing upon contamination or deactivation Play is possible.

In addition, according to the manufacturing method of exemplary embodiments of the present invention, nano iridium oxide particles are dispersed (individual particles are dispersed and / or, without resorting to a complicated manufacturing method requiring a conductor such as conventional carbon black). It is possible to provide a method for producing the above-described hydrogen ion electrode in a very simple manufacturing process consisting of only a matrix of polymer composite material in which aggregates of particles are dispersed).

The hydrogen ion electrode polishes and regenerates the surface in a water quality monitoring system that monitors the concentration of hydrogen ions in a solution for a long time, an online measurement system, or a pH measurement of a sample that causes serious contamination of the sensor surface such as food, soil, waste, and biological samples. It can be useful while going.

1 and 2 is a schematic diagram showing a pH sensor including a hydrogen ion electrode according to an embodiment of the present invention. 1 is a schematic perspective view of a pH sensor, and FIG. 2 is a schematic cross-sectional view.

3 and 4 are transmission electron microscope (TEM) photographs showing nano iridium oxide particles or aggregates prepared in Examples of the present invention. FIG. 3 shows aggregates with the scale bar sized at 10 nm, and FIG. 4 shows individual particles in the aggregates with scale bars at 2 nm.

5 is a graph showing the voltage change according to the pH change of the hydrogen ion electrode made of a composite material of nano iridium oxide and polymer resin in the embodiment of the present invention (reference electrode: Ag / AgCl). In FIG. 5, the X axis represents time (seconds) and the Y axis represents potential (mV).

6 is a graph showing the dependence of the electrode voltage on the pH change of the hydrogen ion electrode composed of nano iridium oxide and a polymer composite material in an embodiment of the present invention. In FIG. 6, the X axis represents pH and the Y axis represents potential (mV).

7 is a graph showing the response time according to the pH change of the hydrogen ion electrode made of nano iridium oxide and a polymer composite material in an embodiment of the present invention. In FIG. 7, the X axis represents time (seconds) and the Y axis represents potential (mV).

FIG. 8 is a graph showing the reproducibility of a hydrogen ion response slope according to surface polishing of a hydrogen ion electrode composed of nano iridium oxide and a polymer composite material in an embodiment of the present invention. In FIG. 8, the X axis represents the measurement cycle, and the Y axis represents the hydrogen ion response slope (mV / pH).

Figure 9 is a graph showing the stability over time of the hydrogen ion response slope of the hydrogen ion electrode composed of nano iridium oxide and polymer composite material in the embodiment of the present invention. In FIG. 9, the X axis represents the measurement primary and the Y axis represents the hydrogen ion response slope (mV / pH).

[Description of Drawing Reference]

11: hydrogen ion electrode 12: conductive bonding site

20: electrical contact means 30: housing

31: open area

Hereinafter, exemplary embodiments of the present invention will be described in detail.

In the present specification, the iridium oxide is an iridium oxide or a hydrated iridium oxide (IrO _y or IrO _y nH ₂ O; for reference, where y corresponds to 2 in the bulk composition but is a nano oxide having a very small particle size and a very large surface area. In the case of, the value cannot be specified).

Nano iridium oxide herein includes nano iridium oxide particles or aggregates thereof.

In the present specification, the aggregate refers to the aggregation of nano iridium oxide particles to form a cohesive unit that is distinguished from each other.

Exemplary embodiments of the present invention are hydrogen ion electrodes in which nano iridium oxide particles having a size of 1 to 10 nm are dispersed in a moldable thermoplastic and hydrophobic polymer resin matrix, wherein the nano iridium oxide particles are electrically connected in a matrix to form hydrogen ions. Provided is a hydrogen ion electrode capable of surface regeneration made of a composite material of nano iridium oxide and a polymer resin that enables electrical conduction of an electrode.

Specifically, the surface reproducible hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin according to an exemplary embodiment of the present invention, nano-iridium having a size of 1 to 10 nm in a moldable thermoplastic and hydrophobic polymer resin matrix A hydrogen ion electrode in which oxide particles are dispersed (dispersed in an individual particle state and / or in a cohesive state in which the particles are partially aggregated), wherein nano iridium oxide particles and / or their dispersed in the polymer resin matrix Aggregates are present so that at least some or all of them are electrically connected in the polymer matrix, thereby enabling electrical conduction of the hydrogen ion electrode. As such, the structure in which the nano-sized nano iridium oxide particles and / or their aggregates of 1 to 10 nm are dispersed to be electrically connected in the polymer matrix of the hydrogen ion electrode may provide a significant advantage in comparison with the conventional hydrogen ion electrodes. Turned out to be.

That is, in the case where the surface of the hydrogen ion electrode is regenerated by polishing or the like (usually, the sensitivity is poor upon surface regeneration due to polishing), the hydrogen ion electrode exposed to the surface is contacted and connected in the polymer resin matrix to enable electrical conduction. 1-10 nm nano iridium oxide particles and / or aggregates thereof (which become hydrogen ion sensitive materials) can be readily reacted to the sample solution (quickly reacting pH sensitive equilibrium with the sample solution). In addition, it can increase the reproducibility of immediate response and lower the hysteresis even in case of repeated use or rapid pH change.

In addition, in the polymer resin matrix in which the nano iridium oxide particles and / or aggregates thereof are dispersed, substantially no pores exist so that penetration of the sample solution through the pores of the sample solution at the surface (the surface to be the electrode sensitive portion) is substantially achieved. While rarely occurring, the sample solution may be in rapid contact with the nano iridium oxide particles and / or aggregates thereof dispersed as described above.

In an exemplary embodiment, nano iridium oxide particles of 1-10 nm size are dispersed in a matrix in individual particle states and are electrically contacted, connected (ie, forming a path of electrical conduction) to the electrical of the hydrogen ion electrode. You can make evangelism possible.

In an exemplary embodiment, nano iridium oxide particles of 1-10 nm size may form aggregate units of nano iridium oxide particles, the aggregate units at least in part contacting and interconnecting (to form a path of electrical conduction) hydrogen Electrical conduction of the ion electrode can be enabled. As such, when the nano iridium oxide aggregated unit in which the nano iridium oxide particles having the size of 1 to 10 nm are aggregated is dispersed in the polymer resin matrix, there is an advantage in that the electrode sensitive part may provide a large specific surface area to contact the sample solution.

In an exemplary embodiment, the individual particle states and aggregates may be in a mixed state, and the particles and / or aggregates may be in contact with each other (to form a path of electrical conduction) to enable electrical conduction of a hydrogen ion electrode. It can be done.

As described above, in order to achieve near ideal pH sensitivity, high reproducibility, excellent surface reproducibility, low hysteresis, etc., the size of the nano iridium oxide particles of the composite material of exemplary embodiments of the present invention is 1-10 nm, or 2-2. 10 nm, or 2 to 5 nm, or 2 to 4 nm. In addition, when the size of the nano iridium oxide particles is smaller than 1nm, there is a difficulty in separation filtration (collection) of the nano iridium oxide particles, when larger than 10nm it is difficult to manufacture a composite electrode material and the electrode properties may be reduced. In addition, the nano iridium oxide particles may have a size of 2 to 10 nm, or 2 to 5 nm, or 2 to 4 nm in terms of preparing nano iridium oxide particles and composite electrode materials and maintaining electrode characteristics.

In an exemplary embodiment, the hydrogen ion electrode may be dispersed in the polymer resin in the nano iridium oxide aggregates, thereby increasing the pH from 3 to 11 and then dropping back to 3, such as rapid (large) pH change or repeated use. Nevertheless, it can show very low hysteresis of 1 ~ 2mV. This hysteresis characteristic is very excellent compared to the conventional iridium oxide coating electrode, iridium oxide and glass or ceramic composite electrode.

In an exemplary embodiment, the hydrogen ion electrode may be made of 20 to 45% by weight of the nano-iridium oxide particles having a size of 1 ~ 10nm and 80 to 55% by weight of the polymer resin. For reference, the nano iridium oxide weight can be measured through a method such as thermogravimetric analysis. When the nano iridium oxide particles having a size of 1 to 10 nm are less than 20% by weight, the electrical conductivity required by the hydrogen ion electrode may not appear, and when the content exceeds 45% by weight, the physical stability of the hydrogen ion electrode may be decreased. An increase may appear, which may cause a problem of desensitization.

In an exemplary embodiment, the polymer resin is a moldable thermoplastic and hydrophobic polymer resin having a glass transition temperature (T _g ) of 20 ° C. or higher that can be dissolved in a water-soluble organic solvent or a mixture of polymer resins having the above characteristics. Such resins can be, for example, PMMA (polymethylmethacrylate) resins, PVC (polyvinylchloride) resins or ABS (acrylonitrile butadiene styrene) resins or mixtures thereof. The resins will have a solid phase within the electrode operating temperature range below the glass transition temperature (T _g ).

Exemplary embodiments of the invention also provide a pH sensor comprising a housing, the hydrogen ion electrode located within the housing and electrical contact means connected to the hydrogen ion electrode. The hydrogen ion electrode contacts the sample to be measured to become an electrode sensitive portion. That is, the sensor may be dispersed in the moldable thermoplastic and hydrophobic polymer matrix so that the nano iridium oxide particles and / or aggregates thereof are electrically connected to each other, thereby making the electrode sensitive portion a composite material which may have electrical conductivity. do.

1 and 2 are schematic diagrams illustrating a pH sensor including a hydrogen ion electrode according to an exemplary embodiment of the present invention. 1 is a schematic perspective view of a pH sensor, and FIG. 2 is a schematic cross-sectional view.

The hydrogen ion electrode 11 described above is formed into, for example, a cylindrical shape, and comes into contact with a sample on one surface to form an electrode sensitive portion. The other side of the hydrogen ion electrode is connected to the electrical contact means 20 such as a conductive metal wire or a metal rod. In this case, the electrical contact means 20 may be connected to the hydrogen ion electrode 11 through the conductive adhesive portion 12 made of silver paste or silver epoxy. The hydrogen ion electrode can be mounted in a non-electrically conductive housing 30, for example plastic, to form a pH sensor. The housing 30 has an open portion 31 formed at one side thereof, and the hydrogen ion electrode 11 serving as the electrode sensitive portion is exposed to the sample solution through the open portion 31.

In exemplary embodiments of the present invention, a method of manufacturing the hydrogen ion electrode may also include a moldable thermoplastic and hydrophobic polymer resin, nano-iridium oxide particles having a size of 1 to 10 nm, and / or aggregates and water-soluble organic particles of the nano-iridium oxide particles. Preparing a mixed solution of a solvent; Adding water to the mixed solution and removing a water-soluble organic solvent to obtain a composite material of a polymer resin and a nano iridium oxide; And forming a hydrogen ion electrode by heating the composite material to provide a method of manufacturing a hydrogen ion electrode comprising a composite material of nano iridium oxide and a polymer resin.

This manufacturing method can be molded and manufactured in various sizes and shapes at a low temperature compared to the pH electrode manufactured by conventional pyrolysis, sputtering, high temperature firing, etc., and also there is no addition and dispersion of carbon black as a conductor. It is very easy to manufacture and has the advantage of exhibiting improved pH sensitivity and reproducibility, low hysteresis and the like. In addition, the prepared hydrogen ion electrode may have the electrical conductivity required for the pH electrode due to the electrical conductivity of the nano iridium oxide particles, even though it does not include carbon black as a conductor.

In detail, first, nano iridium oxide particles and / or aggregates of 1 to 10 nm in size used in exemplary embodiments of the present invention are synthesized by, for example, a synthesis method of reducing an iridium precursor, or distilled water into a commercial nano iridium oxide powder. It may be prepared by grinding and dispersing by adding ultrasonic waves.

The thermoplastic and hydrophobic polymer resin should maintain physical strength at room temperature and be easy to manufacture. In this regard, a moldable thermoplastic and hydrophobic polymer resin having a glass transition temperature (T _g ) of 20 ° C. or more or a mixture thereof may be used. Such resins can be, for example, PMMA (polymethylmethacrylate) resins, PVC (polyvinylchloride) resins or ABS (acrylonitrile butadiene styrene) resins or mixtures thereof. The resins will have a solid phase within the electrode operating temperature range below the glass transition temperature (T _g ).

The water soluble organic solvent may be, for example, acetone, THF (tetrahydrofuran), DMF (dimethylformamide) or DMSO (dimethylsulfoxide).

On the other hand, in the mixed solution manufacturing process, if necessary to control the hardness of the electrode, non-conductive and inert fine powder, such as titanium dioxide (TiO ₂ ), may be further added in a range that does not impair the technical features of the present invention.

When preparing a mixed solution of the polymer resin, the prepared nano iridium oxide particles and / or aggregates thereof and the water-soluble organic solvent, the polymer resin medium is dissolved in a water-soluble organic solvent and uniformly dispersed to prepare a mixed solution, and then nano Iridium oxide particles and / or aggregates thereof can be mixed and evenly dispersed in the mixed solution.

Alternatively, nano iridium oxide particles and / or aggregates thereof are mixed with a water-soluble organic solvent and evenly dispersed to prepare a mixed solution, and then the polymer resin is mixed into the mixed solution and nano iridium oxide particles and / or aggregates thereof are mixed with the polymer. It can be dispersed evenly in the resin medium.

Alternatively, a first mixed solution obtained by dissolving the polymer resin in a water-soluble organic solvent is prepared and uniformly dispersed, and a second mixed solution in which the nano iridium oxide particles and / or aggregates thereof are mixed with a water-soluble organic solvent and dispersed is prepared and evenly distributed. After dispersion, the first mixed solution and the second mixed solution may be mixed and the nano iridium oxide particles and / or aggregates thereof may be evenly dispersed in the polymer resin medium.

Subsequently, excess water is added to the mixed solution to remove the water-soluble organic solvent, and the composite material of the nano iridium oxide and the polymer resin in which the nano iridium oxide particles and / or aggregates are evenly dispersed can be separated (or precipitated) from the solvent. have.

Next, the composite material is molded by pressurizing heating to prepare nano iridium oxide and a polymer resin composite hydrogen ion electrode material having electrical conductivity. Here, the pressurized heating molding is preferably made at a temperature below the thermal decomposition temperature of the medium polymer to be used. Meanwhile, in an exemplary embodiment, the composite material may be pulverized to form a powder and then heat-molded.

In an exemplary embodiment, the surface of the prepared hydrogen ion electrode may be polished, and may also be stabilized in deionized water after polishing.

A hydrogen ion electrode made of the composite material by encapsulating the composite material hydrogen ion electrode material of the nano-iridium oxide and the polymer resin manufactured as described above at one end of a non-conductive housing such as a non-conductive cylindrical plastic having an inner diameter of the electrode material or larger. An electrode sensitive portion 11, and forms an electrical contact means 20 such as a conductive metal wire or a rod on the opposite side thereof, and makes electrical contact, and the electrical contact means 20 is measured outside the housing 30. Can be connected to In addition, a contact portion 12 made of conductive silver paste or silver epoxy may be further included between the hydrogen ion electrode 11 and the electrical contact means 20 (see FIGS. 1 and 2).

Alternatively, the composite material hydrogen ion electrode material is molded and encapsulated inside one end of the nonconductive plastic housing by a heat forming method, and polished to form an electrode sensitive portion made of the composite material hydrogen ion electrode material, and the electrical contact to the other. After drilling a hole for the conductive silver paste or silver epoxy using a conductive metal wire or rod to make electrical contact with the sensitive part may be connected to the measuring device on the other side.

Hereinafter, specific embodiments according to exemplary embodiments of the present invention will be described in more detail. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common in the art while making the disclosure of the present invention complete. It is to be understood that the invention is intended to facilitate the practice of the invention.

<실시예 1> <Example 1>

나노 이리듐 산화물 제조 실시예Nano Iridium Oxide Preparation Example

First, 2 g of (NH ₄ ) ₂ IrCl ₆ was added to a 500 ml round bottom flask, 250 ml of deionized water was added to dissolve, and the solution was slowly added with 0.1 M NaOH while stirring well with a magnetic spoon. Adjust to ~ 9.

Mount the condenser in the round bottom flask and stir at 95 ℃ using a water bath, heat for 30 minutes, and cool to room temperature.

The solution turns from a brown to dark blue solution containing precipitated suspension. While measuring pH again, 0.1M NaOH was added to adjust the pH to 8-9, and then heated at 95 ° C. for 30 minutes, and then cooled to room temperature.

Repeating this process 6-7 times, the pH of the solution no longer changes from 8 to 9, and the 1-10 nm nano iridium oxide particles and / or aggregates formed in the solution are collected, washed and again dispersed in acetone.

3 and 4 are transmission electron microscope (TEM) photographs showing aggregates in which nano iridium oxide particles prepared in Examples of the present invention are aggregated. FIG. 3 shows the size of the scale bar at 10 nm, and FIG. 4 is an enlarged picture of the scale bar at 2 nm.

Meanwhile, instead of the above method, for example, nano iridium oxide particles may be prepared by the following method.

나노 이리듐 산화물 제조 변형예Nano Iridium Oxide Manufacturing Variation

50 ml of distilled water is added to 1 g of commercial nano iridium oxide powder, which is ground and dispersed using ultrasonic waves. In order to select nano iridium oxide having a small particle size, 300 ml of deionized water is added to the pulverized nano iridium oxide, and the iridium oxide is dispersed using an ultrasonic wave and a magnetic stirrer.

Wait 10 seconds for the large iridium oxide aggregates to settle and pour the unimmersed nano iridium oxide supernatant into another beaker.

The dispersion in which the nano iridium oxide is dispersed is divided into a centrifuge tube and rotated at 3000 rpm for 15 minutes to sink the nano iridium oxide, and then the supernatant is removed to recover the nano iridium oxide, washed, and dispersed in acetone.

For reference, in the manufacturing process of nano iridium oxide, a water-soluble organic solvent such as THF, DMF, DMSO, or the like may be used instead of acetone depending on the solubility of the polymer.

나노 이리듐 산화물 및 고분자 수지의 복합 재료의 제조Preparation of Composite Material of Nano Iridium Oxide and Polymer Resin

The PMMA resin is placed in a glass container, acetone is added, a small magnetic paddle bar is sealed, sealed and stirred well with a magnetic paddle to completely dissolve the polymer resin to prepare a polymer solution having a weight ratio of 25% (first mixed solution preparation).

Acetone is added to the nano iridium oxide prepared in the previous example to add a volume ratio of about 1: 3 and evenly dispersed (preparation of a second mixed solution).

After mixing the first mixed solution and the second mixed solution so that the weight ratio of the nano iridium oxide and the polymer resin solid component is 0.37: 0.63, the nano iridium oxide is completely dispersed in the polymer solution using an eccentric stirrer. Mix until

When the polymer solution in which the nano iridium oxide is dispersed is slowly added to the excess water, the water-soluble solvent acetone is removed from the polymer mixture in which the nano iridium oxide is dispersed and precipitated as a solid to form a composite material composed of the nano iridium oxide and the polymer resin. . The composite material thus extracted is dried and ground using a grinder to form a powder.

나노 이리듐 산화물 및 고분자 수지의 복합 재료로 이루어진 수소 이온 전극 제조Preparation of Hydrogen Ion Electrode Composed of Composite Material of Nano Iridium Oxide and Polymer Resin

The prepared nano-iridium oxide-PMMA polymer composite powder was placed in a mold having a diameter of 2 to 4 mm, and heated and pressed at 150 ° C. to form a nano-iridium oxide-polymer composite having a weak electrical conductivity of about 3 to 4 mm in length. Materials Hydrogen ion electrode materials are prepared.

The nano-iridium oxide-polymer composite material manufactured by molding is encapsulated at one end of a non-conductive cylindrical plastic having an inner diameter corresponding to the diameter of the electrode material to form the nano-iridium oxide-polymer composite electrode sensitive portion, and the conductive silver paste is coated. Insert metal wire or rod to make electrical contact, and fix the entrance of the group with adhesive. The electrode sensitive surface is ground finely with 2000 grit SiC sandpaper and then finally polished with 0.3 micron alumina abrasive. The electrode polished surface of the sensitive part is stabilized by immersing it in deionized water.

<실험예> Experimental Example

전극의 감응 특성 확인Check the response characteristics of the electrode

The response characteristic of the hydrogen ion electrode (denoted by electrode # 29: containing 37% of nano iridium oxide as a result of thermogravimetric analysis) composed of the composite material of the nano iridium oxide and the polymer resin prepared above was measured.

Soak a commercial pH glass electrode in a universal buffer solution containing 0.01 M phosphate-boric acid-acetic acid-potassium chloride, adjust the pH to 3, add potassium hydroxide and nitric acid, and change the pH in the range of 3-11. The potential was measured with respect to the Ag / AgCl (3.0 M KCl) reference electrode, and the results are shown in FIG. 2. At this time, the pH was increased to pH 11, and then nitric acid was added again to change the pH to 3 repeatedly.

As shown in Figure 5, it can be seen that the potential of the electrode is quickly stabilized to a new potential in accordance with the pH change of the solution.

As shown in the last part of FIG. 5, after the step of pH change experiment, the pH of the solution was drastically adjusted to 11, and then the electrode was immediately reacted when the pH was measured and the pH was changed to 3 again. It can be seen that after the hysteresis of the stabilization.

Meanwhile, electrode potentials corresponding to respective pHs measured in FIG. 5 are shown in FIG. 5.

The nano-iridium oxide-polymer modified composite hydrogen ion electrode according to the exemplary embodiments of the present invention showed a slope of −59.7 ㎷ / pH unit and was found to be very close to the theoretical value of −59.2 ㎷ / pH unit.

전극 신호의 응답성 확인Confirm responsiveness of electrode signal

In order to confirm the response speed of the prepared composite material of the nano iridium oxide and the polymer resin hydrogen electrode (marked as electrode # 29: 37% nano iridium oxide as a result of thermogravimetric analysis), 0.01M of universal buffer solution The pH was adjusted to 3.04 and the solution was stirred well, and a certain amount of 0.1 M NaOH solution was quickly added to change the pH of the solution to 6.99 near 7, and the response characteristics of the electrode over time were recorded. After adding a certain amount of 0.1M HCl again, the pH of the solution was changed to 2.97 near 3, and the pH of the solution was changed to 6.91 by adding 0.1M NaOH.

Typically, the response characteristic of the electrode signal is calculated as τ ₉₀ , when the electrode potential reaches 90% of the stable potential value, but in the case of the response characterization experiment of this embodiment, the mixture of 0.1 M HCl solution or 0.1 M NaOH solution is added. The exact value of τ ₉₀ was impossible to estimate because it showed a faster response than the time required. This is because the pH electrode of embodiments of the present invention exhibits immediate sensitivity.

전극의 표면 재현성 확인Check surface reproducibility of electrode

The surface of the prepared electrode (denoted by electrode # 29: thermogravimetric analysis contains 37% of nano iridium oxide) was polished with 2000 grit SiC sandpaper, and then polished with 0.3 micrometer alumina abrasive. After immersing and stabilizing one electrode in deionized water, the measurement of the pH sensitivity change of the electrode by polishing was repeated 8 times after the polishing process for measuring the sensitivity of the electrode in

pH

4, 7, 10 solution. Indicated.

As can be seen from FIG. 8, the average slope (pH / pH unit) of the pH sensitivity was -58.12 mW / pH unit, and showed an excellent relative standard deviation (rsd) of 0.5%.

전극의 감응도의 재현성 확인Confirm reproducibility of electrode sensitivity

The result of investigating the change in the sensitivity of the electrode according to the long-term use of the prepared composite material of the iridium oxide and polymer resin hydrogen ion electrode (indicated by electrode # 29: 37% nano iridium oxide) is shown in FIG.

In Fig. 9, the electrode sensitivity at

pH

4, 7,10 is repeatedly measured over 26 days and the electrode sensitivity calculated from the results is also shown. The electrode was measured daily and stored in distilled water.

As a result of analyzing the results of FIG. 9, the average slope of the electrode sensitivity was -58.44 mV / pH, and the relative standard deviation was 0.91%, indicating that the sensitivity was reproducible over a long period of time.

In addition, a composite hydrogen ion electrode 1 month after initial use (marked as electrode # 29: containing 37% of nano iridium oxide as a result of thermogravimetric analysis) was used for 20 times at

pH

4, 7, and 10 buffers. The average value of the pH response slope calculated from the measured value was -58.69 mV / pH unit, and the relative standard deviation of the slope (rsd) was 0.44%, and the reproducible pH sensitivity was confirmed.

As described above, in the hydrogen ion electrode according to the embodiments of the present invention, the nano-iridium oxide aggregate is dispersed in the polymer resin matrix described above, so that the pH response of the electrode surface exposed to the measurement sample solution may be very fast and close to the ideal. In addition, in particular, it has a high reproducibility with such a fast and near ideal sensitivity, and may exhibit very low hysteresis of 1 to 2 mV despite rapid pH change and repeated use. In addition, it can exhibit not only durability due to high physical strength, but also high surface regeneration by polishing, and reproducible electrode surface can be reproduced by simple polishing in case of contamination or deactivation. The lifetime of the hydrogen ion electrode can be significantly extended.

The present invention relates to a hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin and capable of surface regeneration by surface polishing, a pH sensor using the same, and a manufacturing method thereof. The hydrogen ion electrode polishes and regenerates the surface in a water quality monitoring system that monitors the concentration of hydrogen ions in a solution for a long time, or in an online measurement system, or in a pH measurement of a sample that causes severe contamination of the sensor surface such as food, soil, waste, and biological samples It can be useful while going.

Claims

Hydrogen ions in which nano iridium oxide particles having a size of 1 to 10 nm are dispersed in an individual particle state, or in an aggregate state in which the particles are aggregated, or in a state in which the individual particles and aggregates are mixed in a moldable thermoplastic and hydrophobic polymer resin matrix. As an electrode,

And the nano iridium oxide particles are electrically connected in a matrix to enable electrical conduction of the hydrogen ion electrode. The surface reproducible hydrogen ion electrode comprising a composite material of nano iridium oxide and a polymer resin.
The method of claim 1,

The nano iridium oxide particles having a size of 1 to 10 nm are dispersed in individual particle states, and the individual particles are electrically connected to each other to enable electrical conduction of a hydrogen ion electrode. Surface reproducible hydrogen ion electrode made of composite material.
The method of claim 1,

The nano-iridium oxide composite material of the nano-iridium oxide and the polymer resin, characterized in that the nano-iridium oxide particles of the size of 1 ~ 10nm are dispersed in the aggregated state, the aggregates are electrically connected to enable the electrical conduction of the hydrogen ion electrode Surface renewable hydrogen ion electrode consisting of.
The method of claim 1,

The nano iridium oxide particles having a size of 1 to 10 nm are dispersed in a mixture of individual particle states and aggregate states, and the particles or aggregates are electrically connected to each other to enable electrical conduction of a hydrogen ion electrode. A surface reproducible hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin.
The method of claim 1,

The hydrogen ion electrode is a surface renewable hydrogen ion electrode made of a composite material of nano iridium oxide and polymer resin, characterized in that the hysteresis voltage is 1 ~ 2mV according to the pH change to increase the pH from 3 to 11 and then back to 3 .
The method of claim 1,

The hydrogen ion electrode is a surface renewable hydrogen ion electrode made of a composite material of nano iridium oxide and polymer resin, characterized in that the nano-iridium oxide particles 20 to 45% by weight and the polymer resin 80% to 55% by weight.
The method of claim 1,

The polymer resin is a surface renewable hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin, characterized in that the glass transition temperature (T g ) is 20 ° C or more of a polymer resin or a mixture of polymer resins.
Non electrically conductive housing,

The hydrogen ion electrode according to any one of claims 1 to 7 located in the housing and

PH sensor, characterized in that it comprises an electrical contact means connected to the hydrogen ion electrode.
The method of claim 8,

The housing is a cylindrical housing,

On one side of the cylindrical housing there is an open portion for exposing the hydrogen ion electrode to the outside,

PH sensor, characterized in that the electrical contact means is connected to the outside of the housing on the other side of the cylindrical housing.
Preparing a mixed solution of at least one water-soluble organic solvent selected from the group consisting of a moldable thermoplastic and hydrophobic polymer resin, nano iridium oxide particles having a size of 1 to 10 nm and aggregates in which the nano iridium oxide particles are aggregated;

Adding water to the mixed solution and removing a water-soluble organic solvent to obtain a composite material of a polymer resin and a nano iridium oxide; And

The method of manufacturing a hydrogen ion electrode comprising a composite material of nano iridium oxide and a polymer resin, characterized in that it comprises the step of heating the composite material to produce a hydrogen ion electrode.
The method of claim 10,

In the mixed solution preparation step, the polymer resin is dissolved and dispersed in a water-soluble organic solvent to prepare a first mixed solution, and one or more of the nano iridium oxide particles and aggregates are mixed with a water-soluble organic solvent and dispersed to form a second mixed solution. The method for producing a hydrogen ion electrode comprising a composite material of nano iridium oxide and a polymer resin, wherein the first mixed solution and the second mixed solution are mixed and dispersed.
The method of claim 10,

The composite material is pulverized to form a powder and heat-molded to produce a hydrogen ion electrode, the method for producing a hydrogen ion electrode consisting of a composite material of nano iridium oxide and a polymer resin.
The method of claim 10,

Method for producing a hydrogen ion electrode made of a composite material of nano iridium oxide and a polymer resin, characterized in that the surface of the prepared hydrogen ion electrode is stabilized in water after polishing.
The method according to any one of claims 10 to 13,

The manufacturing method further comprises the step of mounting the heat-molded hydrogen ion electrode in a non-electrically conductive housing and connecting electrical contact means to the hydrogen ion electrode. Method for producing a hydrogen ion electrode consisting of.