KR20140013326A - Metal oxide electrode for water electrolysis and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a metallic oxide electrode which is used to generate disinfectant which is harmless to human body by performing electrolysis of tap water and a manufacturing method thereof. Particularly, the present invention relates to a manufacturing method the metallic oxide electrode and the metallic oxide electrode which is manufactured thereby which comprise: (1) a step of preparing a base metal of electrode; (2) a step of etching in order to form surface profile in the base metal of electrode; (3) a step of cleaning the etching fluid with water; (4) a step of obtaining a coating fluid by mixing at least one kind which is selected form platinum (Pt) compound, iridium (Ir) compound, stannum (Sn) compound, titanium (Ti) compound and tantalum(Ta) compound in an organic solvent. (5) The following steps are included in order to form a coating layer in the base metal of electrode by using the coating fluid: (5-1) a step of drying after spreading the coating fluid in the base metal of electrode; (5-2) a step of firstly heat treating; (5-3) a step of forming a coating layer which has a thickness having the electrical efficiency for performing the electrolysis without detaching from the base metal of electrode by repeating the (5-1), (5-2) steps for 10-15 times; (6) a step of secondly heat treating. [Reference numerals] (AA) Preparing of base metal; (BB) Sanding treatment; (CC) First cleaning; (DD) Etching; (EE) Second cleaning; (FF) Drying; (GG) Preparing a coating fluid; (HH) Metallic chloride; (II) Isoprophylene alcohol; (JJ) Mixing (Stirring:30-60 minutes); (KK) Dispersing (Ultrasonic waves:30-60 minutes); (LL) Coating; (MM) Drying; (NN) First heat treating; (OO) Cooling; (PP) Final heat treating; (QQ) Repeating (10-15 times)

Description

Metal oxide electrode for tap water electrolysis and manufacturing method thereof

The present invention relates to a metal oxide electrode and a method of manufacturing the same, and more particularly to a metal oxide electrode for improving the electrolytic performance and harmfulness of the electrode used when electrolyzing tap water to generate a sterilizing agent and a method for producing the same. It is about.

In general, as the hygiene of the home is important, the attention of household fungicides has emerged, and the demand for disinfection and disinfection that is harmless to the human body is increasing. However, disinfection using chemicals, which is a conventional treatment method, has a high hazard to the human body, requires attention to use and handling, has a disadvantage of diluting to a constant concentration during use, and is not easy to maintain sterilization power. Complement the disadvantages of the conventional drug sterilization method, and easy to use and handle, electrolytic disinfectant disinfectant production method using an electrochemical oxidation, reduction reaction that is harmless to the human body has been applied. It is well known that hypochlorite with excellent sterilizing power can be obtained by electrolysis of brine or tap water.

The electrolysis unit cell is composed of a positive electrode and a negative electrode. When a direct current is applied to chlorine ions existing between the positive electrode and the negative electrode, the following electrode reactions occur.

Anode:

_{2H 2 O → O 2 ↑ +} 2H + + 2e - ... ... ... ... ... ... Scheme 1

_{^{2Cl - → Cl 2 + 2e -}} ... ... ... ... ... ... Scheme 2

Cathode:

^{_{2H 2 O + 2e - → H}} 2 ↑ + 2OH - ... ... ... ... ... ... Scheme 3

Reaction in solution

_{Cl 2 + H 2 O → HClO} + H + + Cl - ... ... ... ... ... ... Scheme 4

Oxygen gas (O ₂ ) and chlorine gas (Cl ₂ ) are generated as water or chlorine ions lose electrons at the anode surface, and the production rate of oxygen gas (O ₂ ) and chlorine gas (Cl ₂ ) is applied to the anode. Determined by the electrode catalyst. At the surface of the cathode, water molecules receive electrons to generate hydrogen gas (H ₂ ). Chlorine gas produced at the anode continues to react with water in solution to produce hypochlorous acid (HClO). The method of generating a disinfectant disinfectant by electrolysis has the advantage of being relatively simple to use the electrolyte contained in the water by electrochemical decomposition only by the operation of voltage and current.

However, electrolysis is important as the electrode surface reaction using the positive electrode and the negative electrode having conductivity, as can be seen in the reaction scheme is important to select the appropriate electrode for the positive electrode and the negative electrode. At the positive electrode, the generation of oxygen by the oxidation of water or OH ⁻ occurs competitively, and if it is not very acidic solution, the reaction potential of oxygen generation is lower than that of the chlorine generation reaction, making the chlorine generation reaction thermodynamically unstable. Therefore, the electrode used as the anode should use a large overpotential for oxygen generation and a small overpotential for chlorine generation. Such high oxygen overvoltage anode materials include platinum-based elements such as Pt, Ru, Ir, etc., but have a disadvantage of being very expensive.

Therefore, there has been a demand for the development of electrodes having a relatively low cost while having excellent oxygen overvoltage and durability of platinum-based elements. The study of anode materials using metals such as titanium, zirconium, tantalum, molybdenum, columbium, tungsten, etc. as substitutes for platinum-based elements was conducted in the mid-20th century. Was done vigorously. These metals have high electrical conductivity and excellent durability in an acidic or alkaline aqueous solution, but have exhibited a problem of rapidly increasing resistance when electricity is applied. This is because an oxide film is formed on the surface of the electrode, and eventually the performance as an electrode is lost due to the growth of the oxide film. In the early 1950s, research on the oxide catalyst electrode having conductivity by injecting heterogeneous elements into the TiO ₂ lattice using the semiconducting properties of the oxide film of TiO ₂ formed on the surface of titanium began. As a result, the DSA (Dimensionally Stable Anode) electrode made by incorporating TiO ₂ into RuO ₂ was developed and commercialized. However, the DSA electrode has a problem in that RuO ₂ is eluted to RuO ₄ by oxygen generated at the anode, thereby losing catalytic activity and generating toxic substances harmful to the human body.

In order to solve such a problem, a general method of manufacturing an insoluble oxide catalyst electrode is a method of manufacturing an electrode by forming a coating layer by brushing or applying a metal chloride, nitride, hydrate, etc. providing a noble metal element on the surface of the electrode and forming a coating layer The activity varies depending on the type, ratio, heat treatment temperature, time of the added element, pretreatment method of the electrode, and the like.

Korean Patent No. 403235 discloses a method of preparing a coating liquid based on ruthenium-iridium-titanium and an electrode pretreatment method through hydrochloric acid etching without using an existing substrate etching method, oxalic acid. In addition, Korean Patent Application No. 10-2000-7014261 discloses a method for preparing a coating solution and a coating method based on H ₂ PtCl ₆ -RuCl ₄ -SnCl ₄ .

However, the characteristics of these electrodes provide a coating composition of the electrode having properties similar to those of electrodes using only platinum group elements, but basically have a problem of using Ru compounds, which are harmful to the human body.

The present invention provides a metal oxide electrode for producing hypochlorite with high efficiency and low power when electrolyzing tap water to generate a bactericide, and producing a bactericide that is harmless to a human body and a method of manufacturing the same.

In order to achieve the above object, the present invention is organic to at least one selected from platinum (Pt) compound, iridium (Ir) compound, tin (Sn) compound and titanium (Ti) compound, tantalum (Ta) compound in the electrode base material It provides a metal oxide electrode and a method of manufacturing the same, comprising a coating layer formed by coating and drying the coating solution mixed with a solvent on the electrode base material and repeating the first heat treatment several times, followed by a second heat treatment (final heat treatment). do.

The present invention can be used as an electrode material for electrolyzing tap water through a method of manufacturing a high-efficiency metal oxide electrode, hypochlorous acid can be generated with high efficiency and low power, and household sterilization field that produces a disinfectant that is harmless to the human body. Many applications are expected.

1 is a view schematically showing the process of the present invention.

In order to achieve the above object, the present invention will be described in detail. 1 is a view schematically showing the process of the present invention.

The present invention is the electrode base material; Coating and drying a coating solution obtained by mixing at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound in an organic solvent, A coating layer having a thickness having electrical efficiency necessary for electrolysis without peeling from the electrode base material by repeating the first heat treatment and then performing a second heat treatment (final heat treatment); It provides a metal mixed oxide electrode, characterized in that consisting of.

In addition, the electrode base material is titanium, characterized in that the etching to form a surface roughness, the etching solution is characterized in that the oxalic acid to form a surface roughness of the electrode base material.

In addition, at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound is a chloride, and the organic solvent is isopropyl alcohol. The first heat treatment is performed for 10 to 30 minutes at 300 to 400 ℃ temperature in an oxidizing atmosphere, the second heat treatment (final heat treatment) is performed for 1 to 3 hours at a temperature of 400 to 500 ℃ in an oxidizing atmosphere It is characterized by.

Also,

(1) preparing an electrode base material;

(2) etching to form surface roughness on the electrode base material;

(3) washing the etchant with pure water;

(4) obtaining a coating solution obtained by mixing at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound in an organic solvent;

(5) to form a coating layer on the electrode base material using the coating liquid,

    (5-1) applying the coating solution to the electrode base material and drying it;

    (5-2) first heat treatment;

   (5-3) repeating steps (5-1) and (5-2) 10 to 15 times to form a coating layer having a thickness having an electrical efficiency required for electrolysis without the coating layer peeling from the electrode base material ;

(6) Provided is a method for producing a metal oxide electrode, comprising the step of performing a second heat treatment (final heat treatment).

The electrode base material is titanium, and etching is carried out in step (2) to form fine unevenness so that coating adhesion is increased on the surface thereof, and the etching solution is 10% oxalic acid.

At least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound is a chloride, and the organic solvent is isopropyl alcohol.

The heat treatment of step (5-2) is carried out for 10 to 30 minutes at 300 ~ 400 ℃ temperature in an air atmosphere, the final heat treatment of (6) is 1 to 3 hours at a temperature of 400 ~ 500 ℃ in an oxidizing atmosphere While it takes place.

The present invention made as described above provides a method of lowering the surface potential of the electrolytic electrode by coating iridium, platinum, tin, manganese, titanium, tantalum and the like having excellent electrical conductivity on a titanium electrode base material having fine unevenness.

The heat treatment of step (5-2) is performed to give a bonding force between the coating liquid and the electrode base material dried at a low temperature, the final heat treatment of step (6) is enough to grow the coated oxide particles to excellent bond strength and surface strength It is intended to give, in this case it is good to supply oxygen to the oxygen atmosphere.

The reason for repeating steps (5-1) and (5-2) in step (5-3) is 10 to 15 times, when the number of coatings is small, the formation of the coating layer is not sufficiently developed, and thus used as a coating electrode base material during electrolysis. The coating layer may be peeled from the titanium electrode base material, and if the number of coating is too high, the electrical conductivity is lowered due to excessive growth of the oxide layer, and thus a high voltage is required.

That is, if the coating thickness is thick enough, coating may be done a small number of times. If the thickness of the coating layer is too thick, and the electrical conductivity is low, it is difficult to secure the electrical efficiency required for the electrolysis. It should be as thick as possible.

Then, titanium is selected as an electrode base material, and platinum, iridium, tin, manganese, titanium, tantalum, and the like are selected as coating materials as follows. That is, since the titanium electrode base material has an acid resistance and chemical resistance and has a relatively high melting point (1668 ° C.), the titanium electrode base material does not deteriorate due to temperature change during electrode coating and heat treatment by pyrolysis.

However, when titanium is used directly as an anode material, the titanium surface is anodized by application of current, and a titanium dioxide (TiO ₂ ) layer, which is an oxide film of metal titanium, is formed so that no current flows. Therefore, by injecting the hetero atoms in the crystal lattice of the titanium dioxide oxide will the addition of elements such as iridium, platinum, tin, manganese, titanium, tantalum to increase the electrical conductivity, and, in order not to produce a harmful RuO ₄ to the human body No Ru compound was added.

As described above, the specific process of the present invention has been described as an example, but the present invention is not limited to the process described and illustrated by way of example, and the general knowledge in the technical field to which the present invention belongs without departing from the spirit of the present invention. Various changes and modifications will be made by those who possess.

Claims (10)

An electrode base material;
Coating and drying a coating solution obtained by mixing at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound in an organic solvent, A coating layer having a thickness having electrical efficiency necessary for electrolysis without peeling from the electrode base material by repeating the first heat treatment and then performing a second heat treatment (final heat treatment); A metal mixed oxide electrode, characterized in that consisting of. The metal oxide electrode as claimed in claim 1, wherein the electrode base material is titanium and is etched to form a surface roughness. The metal oxide electrode according to claim 1, wherein the etching solution is oxalic acid to form the surface roughness of the electrode base material. The method of claim 1, wherein at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound is a chloride, and the organic solvent is isopropyl. Metal oxide electrode, characterized in that the alcohol. The method of claim 1, wherein the first heat treatment is performed for 10 to 30 minutes at 300 to 400 ℃ temperature in an oxidizing atmosphere, the second heat treatment (final heat treatment) at a temperature of 400 to 500 ℃ in an oxidizing atmosphere 1 to 3 Metal oxide electrode, characterized in that made for a time. (1) preparing the electrode base material
(2) etching to form surface roughness on the electrode base material
(3) washing the etchant with pure water
(4) obtaining a coating solution obtained by mixing at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound in an organic solvent;
(5) to form a coating layer on the electrode base material using the coating liquid,
(5-1) applying the coating solution to the electrode base material and drying
(5-2) first heat treatment step
(5-3) repeating steps (5-1) and (5-2) 10 to 15 times to form a coating layer having a thickness having an electrical efficiency required for electrolysis without the coating layer peeling from the electrode base material
(6) A method for producing a metal oxide electrode, comprising the step of performing a second heat treatment (final heat treatment). The method of claim 6, wherein the electrode base material is titanium. The method of claim 6, wherein the etching solution used in the step (2) is oxalic acid. The method of claim 6, wherein in step (4), at least one selected from a platinum (Pt) compound, an iridium (Ir) compound, a tin (Sn) compound, a titanium (Ti) compound, and a tantalum (Ta) compound is a chloride, The organic solvent is a method for producing a metal oxide electrode, characterized in that the isopropyl alcohol. The method of claim 6, wherein the first heat treatment in the step (5-2) is carried out for 10 to 30 minutes at 300 ~ 400 ℃ temperature in an oxidizing atmosphere, the second heat treatment (final heat treatment) in the step (6) Method for producing a metal oxide electrode, characterized in that made for 1 to 3 hours at a temperature of 400 ~ 500 ℃ in the atmosphere.

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