JP3312924B2 - Hypochlorite decomposition catalyst and method for producing hypochlorite decomposition catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, process effluent discharged during the production of sodium hypochlorite or hypochlorous acid contained in a waste liquid obtained by neutralizing chlorine gas with a sodium hydroxide solution. The present invention relates to a catalyst for decomposing hypochlorite such as sodium.

[0002]

2. Description of the Related Art Sodium hypochlorite is contained in process wastewater discharged during the production of sodium hypochlorite. In addition, when chlorine gas is brought into contact with an aqueous sodium hydroxide solution to neutralize the solution, sodium chloride is generated, and sodium hypochlorite is produced as a by-product. It will be.

By the way, the waste liquid containing sodium hypochlorite emits an off-flavor and generates chlorine gas when mixed with an acid solution such as hydrochloric acid. Become. Therefore, conventionally, secondary treatments such as decomposing the sodium hypochlorite contained by adding a reducing agent such as sodium sulfite or hydrogen peroxide solution to the wastewater or wastewater are performed. ing.

[0004]

However, the secondary treatment requires complicated treatment equipment, and the secondary treatment of the sodium hypochlorite-containing solution is industrially required in a large amount. There is a problem that equipment and operation costs increase due to consumption.

The present invention has been made under such circumstances, and it is an object of the present invention to simply and efficiently decompose hypochlorite without elution into a liquid to be treated. It is an object of the present invention to provide a hypochlorite decomposition catalyst which can be produced.

[0006]

SUMMARY OF THE INVENTION The hypochlorous acid according to the present invention
The method for producing a decomposition catalyst for
Etching waste liquid and iron after etching Kel material
And react with the following to form a composite metal of iron and nickel.
A chlorite decomposition catalyst is obtained. This
In such a configuration, for example, react with the etching waste liquid
Iron powder was used for iron, and nickel was deposited on the surface of the iron powder.
To obtain composite metal powder as hypochlorite decomposition catalyst
Is preferred.

[0007]

[0008]

According to the present invention, for example, sodium hypochlorite
As a catalyst for decomposition of the liquid to be treated in the liquid to be treated containing
For example, composite metal powder in which nickel is supported on iron powder (hereinafter referred to as “N
"i composite powder". ) And stir the liquid to be treated
By this, sodium hypochlorite in the liquid to be treated
It can be decomposed and converted into harmless sodium chloride and the like.

According to such a composite metal powder, for example, sodium hypochlorite in a liquid to be treated can be easily and efficiently decomposed into sodium chloride without adding a chemical such as sodium sulfite. The liquid to be treated can be made pollution-free. The reason is that, for example, in the case of a composite metal powder of nickel and iron, a local battery is formed in the liquid to be treated, so that the decomposition reaction of sodium hypochlorite is promoted and a part of the Ni composite powder is Oxidized by sodium chlorite to nickel oxide or iron oxide, etc.
It is presumed that the reaction of these with sodium hypochlorite further accelerates the decomposition reaction of sodium hypochlorite.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is an example of a cracking catalyst according to the present invention,
An example in which a sodium hypochlorite solution was actually treated using the i composite powder will be described.

Here, a method for producing the Ni composite powder will be described. For example, when a nickel material such as an invar material is etched with a ferric chloride solution, the waste liquid after the etching becomes nickel chloride (NiCl2) as shown in the following chemical formula 1.
And iron chloride.

[0013]

[Image Omitted] 2FeCl3 + Ni → NiCl2 + 2FeCl2 When iron scrap is put into the etching waste liquid, nickel is precipitated from the etching waste liquid on the surface of iron as shown in the following chemical formula 2, and the deposited nickel-iron composite metal By separating the powder from the etching waste liquid, a Ni composite powder is obtained.

[0014]

FIG. 1 shows an embodiment of the present invention in 2 liters of a sodium hypochlorite-containing solution (hereinafter referred to as a “sodium hypochlorite solution”) having an effective chlorine concentration of about 12 wt% to about 13 wt%. Such Ni
Decomposition rate when 3 g of the composite powder was charged to decompose sodium hypochlorite and decomposition rate when other reagents such as NiCl2.6H2O were charged and decomposed were calculated. FIG. 4 is a characteristic diagram showing a relationship between the effective chlorine concentration (wt%) and the effective chlorine concentration (wt%). The curves represented by (1) to (6) in FIG. 1 are Ni composite powder, Ni ferrite, and CoCl2.6H2, respectively.
The graph shows changes over time in the effective chlorine concentration when O, NiCl2.6H2O, FeCl2 treated Fe powder and N2O3 are introduced into the sodium hypochlorite solution at a temperature of about 15 DEG C. to 20 DEG C.

As can be seen from FIG. 1, Ni composite powder, Ni ferrite and CoCl
The decrease rate of the effective chlorine concentration over time when each of 2.6H2O was charged was extremely higher than the decrease rate when each of the other reagents such as N2O3 was charged. Composite powder, Ni ferrite and CoCl2.6
It can be said that H2O is excellent as a catalyst for decomposing sodium hypochlorite when focusing only on the decomposition rate of sodium hypochlorite.

However, among these three, Ni ferrite has the problems that the manufacturing process is complicated and that the price is generally higher than that of the Ni composite powder.
Since Cl2.6H2O is a consumable catalyst in which the Co component elutes in the liquid to be treated, it must always be additionally supplied.
If this Co component is taken into the human body, it is harmful, and there is a problem that secondary processing must be performed. On the other hand, since the Ni composite powder does not have such a problem, it can be said that it is extremely excellent as a catalyst for decomposing sodium hypochlorite as compared with the other reagents.

Next, the deterioration (life as a catalyst) of the Ni composite powder will be described. FIG. 2 is a characteristic diagram showing the results of a test on the deterioration of the Ni composite powder. The curves represented by (1) to (3) in FIG.
2 l, 8 l, 16 l of sodium hypochlorite solution having about 12 ° C. and effective chlorine concentration of about 12% to 13% are decomposed, and then 2 l of the sodium hypochlorite solution is further decomposed. FIG. 5 is a characteristic diagram showing a decomposition rate at the time of performing the process in a relationship between a processing elapsed time (minutes) and an effective chlorine concentration (wt%).

As can be seen from FIG. 2, there is no significant difference in the rate of decrease in the effective chlorine concentration over time in each of the above cases.
Therefore, from this result, it can be said that the Ni composite powder is less deteriorated even when used for a long time, and that the catalyst life as a decomposition catalyst for sodium hypochlorite is long. Next, the separability of the Ni composite powder from the sodium hypochlorite solution will be described.
The i-composite powder is a composite metal powder in which nickel is supported on iron powder as described in the section of “action”, and since iron powder, which is a carrier supporting nickel, has strong magnetism, for example, The Ni composite powder can be easily separated from the sodium hypochlorite solution by bringing a magnetic substance such as a magnet into contact with the treatment tank of the sodium hypochlorite solution from the outside. Therefore, it can be said that the Ni composite powder is excellent also in the separability from the sodium hypochlorite solution.

Here, the liquid to be treated is decomposed with the Ni composite powder to recover the treatment liquid, and Ni is removed from the liquid to be treated.
FIG. 3 shows an example of an apparatus for separating the composite powder. FIG.
Reference numeral 1 denotes a decomposition treatment tank for decomposing a liquid to be treated such as sodium hypochlorite. A filter cloth 2 is provided near the bottom of the decomposition treatment tank 1, and a decomposition treatment tank is provided. For example, an electromagnet 3 serving as a separation unit for separating the Ni composite powder from the liquid to be treated is detachably attached to the outer peripheral portion of the side surface of the first side. Near the center of the bottom surface of the decomposition processing tank 1, there is provided a drainage passage 6 for draining the processing liquid from the decomposition processing tank 1 via a valve 4 and a pump 5.

The liquid to be treated is supplied into the decomposition treatment tank 1 by a pumping means such as a pump (not shown).
After charging the Ni composite powder and agitating the liquid to be treated by a stirring means (not shown) for a predetermined period of time, the Ni composite powder is attracted to the electromagnet 3 side of the inner wall of the decomposition processing tank 1 by operating the electromagnet 3. You. Then, while the Ni composite powder is attracted to the electromagnet 3 side, the processing liquid in the decomposition processing tank 1 is pumped through a pump 5 or the like to, for example, a tank (not shown) to collect the processing liquid. The Ni composite powder can be more easily separated.

When the operation of the electromagnet 3 is stopped after the treatment liquid is recovered, the Ni composite powder sucked into the inner wall of the decomposition treatment tank 1 falls on the filter cloth 2, but falls on the filter cloth 2. While the liquid to be treated can be decomposed in the same manner as described above using the Ni composite powder as it is, if the Ni composite powder is deteriorated and replaced, the N powder dropped on the filter cloth 2 is removed.
By recovering the i-composite powder and adding new Ni-composite powder, the Ni-composite powder can be easily replaced.

Next, the dissolution property of the Ni composite powder into the sodium hypochlorite solution will be described. Regarding the treatment solution obtained by separating sodium hypochlorite with Ni composite powder,
Qualitative analysis was performed several times for each of Fe, Ni, Cu, Mn, Zn and Cr, but none of these components was detected. Therefore, it can be said from this analysis result that there is no elution of the Ni composite powder into the sodium hypochlorite solution.

According to the above embodiment, the Ni composite powder is decomposable for sodium hypochlorite, non-degradable as a catalyst for decomposing sodium hypochlorite, separability from sodium hypochlorite solution, and In the comprehensive evaluation of non-elution in sodium hypochlorite solution, it is extremely superior to the other reagents described above, so that sodium hypochlorite solution can be easily and efficiently detoxified. . In addition, this Ni
By decomposing sodium hypochlorite with the composite powder, the secondary treatment as described in the section of “Conventional Technology” is not required, and the Ni composite powder has a long catalyst life, thereby improving the economical efficiency of the treatment. Owing to the excellent separation property from the hypochlorite solution, the recovery process from the hypochlorite solution can be easily performed. Further, since the Ni composite powder is excellent also in non-elution property, for example, it is possible to decompose the hypochlorite and the like in drinking water, so that the selectivity of the liquid to be treated is improved.

In the above, the present invention is not limited to the treatment of a sodium hypochlorite solution, but is also applicable to the treatment of a hypochlorite solution such as a potassium hypochlorite solution. The composite metal of iron and nickel is not limited to the Ni composite powder, but may be, for example, an alloy or oxide in which iron and nickel are mixed.

[0025]

The decomposition catalyst according to the present invention has excellent decomposability of hypochlorite, so that hypochlorite can be decomposed in a short time to eliminate pollution.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the relationship between the elapsed time and the effective chlorine concentration for the decomposition rate of sodium hypochlorite for each of the reagents such as Ni composite powder and NiCl2.6H2O.

FIG. 2 is a characteristic diagram showing a decomposition rate of each specimen in a deterioration test of a Ni composite powder in a relationship between an elapsed time and an effective chlorine concentration.

FIG. 3 is an explanatory view showing an example of an apparatus for decomposing a liquid to be treated and separating Ni composite powder from the liquid to be treated.

[Description of Signs] 1 Decomposition tank 2 Filter cloth 3 Electromagnet 6 Drainage passage

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yu Awaya 1-7 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Inside Tsurumi Soda Co., Ltd. (56) References D. Gokhale "Hypo chlorite waste management in chl (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-37/36 C02F 1/58 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. An etching waste liquid after etching a nickel material using a ferric chloride solution is reacted with iron to obtain a hypochlorite decomposition catalyst comprising a composite metal of iron and nickel. A method for producing a catalyst for decomposing hypochlorite, characterized in that: 2. The hypochlorite according to claim 1, wherein the iron reacting with the etching waste liquid is iron powder, and the composite metal is a composite metal powder obtained by depositing nickel on the surface of the iron powder. For producing a cracking catalyst. 3. A hypochlorous acid comprising a composite metal of iron and nickel obtained by reacting iron with an etching waste liquid after etching a nickel material using a ferric chloride solution. Salt decomposition catalyst. 4. The hypochlorite according to claim 3, wherein the composite metal is a composite metal powder obtained by reacting an etching waste liquid with iron powder to deposit nickel on the surface of the iron powder. Cracking catalyst.