JPS5811021B2 - ozone electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ozone electrode for measuring the concentration of ozone dissolved in a solution.

In recent years, the use of ozone's strong oxidizing action has been used as a method for removing environmental pollutants.

In particular, ozone has been used in many fields, including the oxidative decomposition, decolorization, and sterilization of harmful substances contained in wastewater related to water treatment, as well as the removal of nitrogen oxides and deodorization in gas treatment. There is.

In the various treatment methods described above, it is necessary to control the concentration of supplied ozone to optimal conditions from the viewpoint of reducing operating costs and suppressing secondary pollution caused by unreacted ozone.

Conventional methods for measuring the ozone concentration in gases include chemiluminescence and ultraviolet absorption methods, which are simple and accurate methods, but in order to measure the ozone concentration dissolved in a solution, it is necessary to sample an appropriate amount of the solution. After adding this to a neutral solution of potassium iodide to liberate iodine,
Methods such as measuring the absorbance of m or titrating with sodium thiosulfate have been adopted.

However, this method of measuring ozone concentration in a solution is cumbersome and time-consuming, and does not allow rapid measurement.
Moreover, ozone is easily decomposed and the coloring fades over time, resulting in large measurement errors.

In view of this, the present invention includes an oxygen detector having an oxygen permeable membrane, and the permeable membrane is provided with an ozone decomposition membrane made of a silicone rubber membrane or a fluororesin membrane in which activated carbon is dispersed and dissolved in a solution. The object of the present invention is to provide an ozone electrode that can quickly and accurately measure ozone concentration.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows an ozone electrode 1 according to the present invention. This ozone electrode 1 has a cylindrical holder 2 having an open end, and a cylindrical holder 2 having an open end, which serves both to seal the electrolytic solution 3 and to permeate oxygen. An oxygen permeable membrane 4 is provided, and an oxygen reduction electrode 5 made of platinum, gold, etc. and a counter electrode 6 are provided in the electrolytic solution 3 to form an oxygen detector 7. An ozone decomposition film 8 is formed to cover this.

In the figure, 9 is an O-ring, and 10 is a cap that is attached to the front end of the cylindrical holder 2 and supports the ozone decomposition membrane 8.

The electrolytic solution 3 is, for example, a saturated KCl solution, and the oxygen permeable membrane 4 for sealing the electrolytic solution 3 is made of, for example, fluororesin, polyethylene, silicone resin, or ceramics, but from the viewpoint of chemical stability. In particular, fluororesins are preferred.

Further, an ozone decomposition membrane that decomposes ozone O3 into oxygen gas is composed of a silicone rubber membrane or a fluororesin membrane in which powdered or fibrous activated carbon is dispersed.

As a method for manufacturing the above-mentioned ozone decomposition membrane, for example, 50 to 2,500 mesh, preferably 500 to 2,500 mesh of powdered or fibrous activated carbon is added to a solution of silicone rubber or fluororesin dissolved in a solvent such as acetone or benzene. A method of dispersing the ozone decomposition film 8 with a thickness of about 10 to 500 μm by dispersing the ozone decomposition film 8 by weight of 5 to 50 μm, then applying this dispersion onto a smooth flat plate such as glass, and heating it to sufficiently diffuse the solvent. There is.

Another method is to heat the silicone rubber or fluororesin to plasticize it, add and mix powdered or fibrous activated carbon, and then stretch the mixture onto a smooth flat plate and cool it. There is also a method of producing an ozone decomposition membrane by

The operation of the ozone electrode 1 having the above structure will now be explained.

When the ozone electrode 1 is arranged so that at least its tip side is immersed in the solution to be measured, oxygen dissolved in the solution passes through the ozone decomposition membrane 8 and the oxygen permeable membrane 4 and enters the electrolytic solution 3. Ozone dissolved in the solution is decomposed into oxygen when passing through the ozone decomposition membrane 8, and this decomposed oxygen, like the dissolved oxygen, permeates the oxygen permeable membrane 4 and enters the electrolytic solution 3.

The dissolved oxygen that has entered the electrolytic solution 3 in this way is reduced by the oxygen reduction electrode 5, and the oxygen concentration can be measured by reading the current value generated at this time.

Therefore, separately from this, the dissolved oxygen concentration in the solution is measured,
From the difference between this measured value and the oxygen concentration measured with the ozone electrode, the concentration of ion in the solution can be determined.

Furthermore, since the membrane base material of the ozone decomposition membrane is made of silicone resin or fluororesin, oxidative deterioration due to ozone is less likely to occur, and the service life can be extended.

Moreover, since activated carbon is used as the decomposition agent in the ozone decomposition membrane, the membrane base material is less susceptible to oxidative deterioration, which prevents poisoning effects, and the activated carbon body is also less susceptible to poisoning effects, resulting in a significant reduction in ozone decomposition ability. Improvement can be achieved.

Furthermore, the ozone electrode 1 having the above structure can be used to construct a direct reading type ozone concentration current measuring device as shown in FIG.

This device connects an ozone electrode 1 shown in FIG. 1 and a correction oxygen electrode 11 in which the ozone decomposition membrane 8 is not provided on the ozone electrode 1 to a subtraction calculation circuit 12 in parallel.
A display device 13 is connected to this arithmetic circuit 2.

This direct reading type ozone concentration measuring device calculates the output current from the ozone electrode 1 and the output current from the correction oxygen electrode 11 in a subtraction calculation circuit 12, and displays the ozone concentration in the solution on the display device 13. It is.

In addition, in the above description, the oxygen detector 7 constituting the ozone electrode 1
Although the oxygen reduction electrode 5 and the counter electrode 6 are provided in the electrolytic solution 3, the present invention is not limited to this, and any device having a mechanism for detecting the oxygen concentration may be used. good.

Next, specific examples of the present invention will be described.

As shown in FIG. 1, an oxygen permeable membrane 4 made of polytetrafluoroethylene (PTFE) is provided at the tip of a cylindrical holder 2 containing a saturated KCl solution as an electrolyte 3, and the electrolyte 3 is made of platinum. An oxygen detector 7 is formed by arranging an oxygen reduction electrode 5 and a counter electrode 6 made of silver, and an ozone decomposition membrane 8 having the following structure is closely attached to the outer surface of the oxygen permeable membrane 4 so as to cover it. The ozone electrode 1 was formed.

This ozone decomposition membrane 8 is attached to 20g of silicone rubber by RTV.
Thinner (trade name manufactured by Toshiba Silicone Corporation) 2 g, RTV catalyst (trade name manufactured by Toshiba Silicone Corporation) 0.1 g and 500
After adding 2 g of Metsushiyun's powdered activated carbon (ozone decomposer) and mixing thoroughly, the mixture was coated on a glass plate to a uniform thickness, and further heated at 50°C for 5 hours until it was 65 mm thick. It is made into a sheet.

Further, an oxygen detector 7 without an ozone decomposition membrane 8 provided on the ozone electrode 1 is used as a correction oxygen electrode 11, and as shown in FIG. By connecting this and the display device 13, a direct reading type ozone concentration measuring device as shown in FIG. 2 was assembled.

In addition, the ozone concentration in water adjusted to 20°C was 1.0 g/m3 (No. 1), 5.0 g/m3 (No. 1), and 5.0 g/m3 (No.
No. 2), 7.0 g/m3 (No. 3), 8.5 g/m3
m3 (No, 4) and 10 g/m3 (No, 5) of ozonized air were injected, and after 20 minutes, the above-mentioned ozone electrode 1 and correction oxygen electrode 11 were inserted into the solution to be measured. Ozone concentration was measured.

The oxygen concentration thus measured by the ozone electrode 1 is Appm, the oxygen concentration measured by the corrected oxygen electrode 2 is Bppm, and the ozone concentration in the solution (A-B).
The ppm values are shown in the table below.

In addition, in order to confirm the effects of the present invention, ozone concentrations measured by a conventional method using potassium iodide are also listed in the same table.

As is clear from the above results, the ozone electrode according to the present invention can measure the ozone concentration in a solution with high accuracy using an extremely simple structure, and is also capable of measuring the ozone concentration in a solution using conventional methods using potassium iodide or sodium thiosulfate. It can be measured in a much shorter time than the conventional method, and has remarkable effects such as being able to efficiently control ozone concentration in various wastewater treatments using ozone.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an ozone electrode according to the present invention,
FIG. 2 is a circuit diagram of a direct reading type ozone concentration measuring device using an ozone electrode according to the present invention. 1... Ozone electrode, 2... Cylindrical holder, 3...
Electrolyte solution, 4... Oxygen permeable membrane, 5... Oxygen reduction electrode, 6
...Counter electrode, 7...Oxygen detector, 8...Ozone dispersion membrane, 9...O ring, 10...Cap, 11...
- Correction oxygen electrode, 12... Arithmetic circuit, 13... Display device.

Claims (1)

[Claims] 1. An ozone electrode comprising an oxygen detector having an oxygen permeable membrane, the oxygen permeable membrane being provided with an ozone decomposition membrane made of a silicone rubber membrane or a fluororesin membrane in which activated carbon is dispersed.