JPH06142659A - Method for removing residual chlorine in city water - Google Patents

Abstract

PURPOSE:To easily and surely remove the residual chlorine in city water by bringing the city water into contact with metal titanium at >=90 deg.C, thereby efficiently removing the chrominated lime smells of the city water. CONSTITUTION:The residual chlorine in the city water is removed by bringing the city water into contact with the metal titanium at >=90 deg.C. Namely, the hypochlorous acid or hypochlorite ions existing as the residual chlorine in the city water are brought into reaction with titanium, by which the residual chlorine is finally converted to HC1 and TiO2 and is removed. The by-produced HC1 is brought into reaction with CaCO3 and MgCO3 existing in the city water and is thereby converted to CaCL2 and MgCl2. Further, the metal titanium of a large surface area having granular or porous surfaces is used in order to accelerate such reaction. As a result, the residual chlorine in the city water is easily and surely removed, by which the chlominated lime smells of the city water are efficiently removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Tap water is sterilized with chlorine to eliminate the infectivity of pathogenic microorganisms.

As a result of chlorine being added at the water purification plant, residual chlorine having a bactericidal effect remains in the water flowing out of the water tap at the end.

The free residual chlorine of water in the water supply is
It is stipulated by the Water Supply Law so as to be maintained at 0.1 mg / L or more.

Usually, effective residual chlorine in water tends to gradually change to chlorine ions having no bactericidal effect. Therefore, there is a tendency to increase the injection amount of chlorine in order to maintain the effective residual chlorine concentration in the water supply pipe. is there. For this reason, tap water containing a sufficiently high concentration of residual chlorine for sterilization exhibits a so-called chlorine odor.

The problem of the odor of khaki is also a problem in applications such as recent jar pots in which water is used after boiling. The aim is to increase the boiling time, but it is still not effective enough.

[0006] The present invention relates to a method for removing residual chlorine promptly during boiling in an instrument using boiling water such as a jar pot. Specifically, metallic titanium in boiling water is used. Or
Alternatively, it is intended to remove non-dissociated hypochlorous acid and hypochlorite ions existing as residual chlorine by chlorine ionization by circulating boiling water in contact with the surface of titanium metal.

[0007]

2. Description of the Related Art As a method for removing residual chlorine in tap water in a jar pot, a method of lengthening the boiling time of the jar pot and a method of circulating boiling water in granular activated carbon to remove hypochlorous acid or There is a method of reacting chlorite ion with activated carbon to oxidize the activated carbon.

The method of lengthening the boiling time seems to be the simplest and the best, but if the boiling time is extended to such an extent that it does not pose a practical problem, a clear removal effect cannot be obtained.

Also in the method using activated carbon, activated carbon has a problem that powdery fine powder is produced and mixed when it is used in boiling water because its peeling from the surface is severe in view of its crystal structure. In order to solve this, it is necessary to subject the activated carbon surface to a special surface treatment, and this step is necessary and a coating layer is formed on the surface, which causes problems such as deterioration of original performance. .

[0010]

DISCLOSURE OF THE INVENTION In the present invention, residual chlorine is removed by contacting granular particles of metallic titanium, such as titanium sponge, or those formed into porous moldings with water in a boiling state. It is something to be removed.

Generally, chlorine added to tap water chemically reacts with water to form hypochlorous acid (HOCl) and hydrogen chloride (HC).
l) is generated. At a pH of about 7, about 70% of the generated hypochlorous acid is non-dissociated hypochlorous acid, which is the main body of bactericidal action, and the rest is said to be dissociated into hypochlorite ion (OCl ⁻ ).

The HOCl and OCl ^- have a bactericidal action and become residual chlorine which gives a so-called chlorine odor.

On the surface of titanium metal in water at 90 ° C. or higher, hypochlorous acid or hypochlorite ion is reduced to chlorine ion, and residual chlorine is removed. Since this reaction proceeds fairly quickly in boiling water, it can be treated in a short time and does not generate fine powder unlike activated carbon. Moreover, titanium metal is harmless to the human body as it is used as a biomaterial.

[0014]

According to the present invention, metal titanium is brought into contact with tap water at 90 ° C. or higher to react hypochlorous acid or hypochlorite ion present as residual chlorine with titanium, Finally HCl and TiO
_The HCl, which is converted into ₂ and removed, still reacts with CaCO ₃ and MgCO ₃ existing in tap water, and 2HCl + CaCO ₃ → CaCl ₂ + H ₂ O + CO ₂ 2HCl + MgCO ₃ → MgCl ₂ + H ₂ O + CO ₂ It becomes MgCl ₂ or CaCl ₂ .

In order to cause the above reaction to occur better, it is more effective that the metallic titanium has a granular or porous surface and has a larger surface area, but it may be rod-shaped or plate-shaped. .

Further, this reaction occurs in water that has been boiled at 90 ° C. or higher, and at room temperature this reaction is unlikely to occur.

In addition to titanium metal, iron, zinc, copper, brass,
Aluminum, metal silicon, manganese, etc. have the same effect, but iron, zinc, etc. are leached out a lot and the water becomes turbid, and when left in water, severe rusting occurs. Further, copper, brass, manganese, aluminum, etc. have a risk of damaging the human body.

Although metallic silicon has no problem in terms of harm to the human body, it is inferior to titanium in that it is difficult to handle such as workability.

It can be said that titanium metal is most suitable for this application because it does not react with water at room temperature and is harmless to the human body.

[0020]

[Example] Using an electric jar pot, titanium sponge 10 was added to 2.4 L of tap water having a residual chlorine concentration of 1.0 ppm.
Pour 0 g, boil from room temperature, hold at 92 ℃ after boiling,
The residual chlorine concentration was measured every time after the start of holding.

As a control, the same treatment was performed without adding titanium sponge. The results are shown in the graph of FIG. The present invention shows that residual chlorine can be removed to almost zero in a short time (about 15 minutes). It should be noted that the water treated according to the present invention had no odor of chlorine, but the control-treated water had a slight odor of chlorine.

[Brief description of drawings]

[Fig. 1] Titanium sponge was added to tap water, and after boiling, 92
It is a graph which shows the time-dependent change of the residual chlorine concentration when hold | maintaining at (degree C).

Claims (1)

[Claims] 1. A method for removing residual chlorine in tap water, which comprises contacting tap water with metallic titanium at 90 ° C. or higher.