JPS5946678B2 - Method for producing metal peroxide water treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a water treatment agent, particularly a method for producing a water treatment agent comprising a metal peroxide which is used in the oxidation treatment of COD components such as alcohols and formaldehyde contained in wastewater. It is related to the method.

In recent years, reduction of COD in wastewater from factories, rivers, etc. has been required from the viewpoint of pollution prevention.

Conventionally, methods for reducing COD include activated sludge method, activated carbon adsorption method, ozone oxidation method, chlorine-photooxidation method, electrolytic flocculation method and electrolytic flotation method using soluble electrodes such as aluminum and iron. Some have been proposed and some have been implemented.

However, among these methods, the activated sludge method
Some substances are effective for reducing COD, but are not effective for COD or depending on their components.

In addition, the activated carbon adsorption method has little effect on organic substances that are highly hydrophilic COD components, such as low molecular weight alcohols.

Although the ozone oxidation method is effective for deodorizing, decolorizing, and sterilizing,
The oxidizing power is strong and not necessarily sufficient to reduce COD.

Although the chlorine photooxidation method is a treatment method with relatively strong oxidizing power, it requires a large amount of electricity and a long treatment time because it is used for dilute COD components or uses an ultraviolet generating lamp, for example.
This method requires a large amount of equipment and processing costs, and cannot be said to be an economically advantageous method.

In addition, the electrolytic treatment method has a high oxidation potential for low-molecular-weight hydrophilic organics (in reality, almost no oxidation due to an electric field can be expected, and the electricity cost is high (and is not suitable for treating large amounts of wastewater, etc.). None of these methods was necessarily satisfactory in terms of effectiveness or economy.

On the other hand, a method has been proposed in which a metal peroxide such as nickel peroxide is used to oxidize a COD component in the presence of a primary chlorite.

(For example, see Japanese Patent Application Laid-open No. 49-37465.) Although this method is considerably more effective than the conventional COD component reduction method described above, it may partially react with the wastewater itself during long-term use, or For example, if the supply of the required amount of hypochlorite becomes insufficient due to fluctuations in the amount of wastewater to be treated, the peroxide will be converted to a more stable lower oxide, and the COD component will not lose its activity. This will interfere with processing.

Once a metal peroxide is converted to a lower oxide, no matter how much it is brought into contact with hypochlorite in this state, it takes a considerable amount of time to convert it back to a metal peroxide. It is not appropriate to continue treating wastewater that still contains metal oxides.

As a result of various studies and examinations aimed at converting metal peroxides that have become low-level oxides into sufficiently active metal peroxides in a short period of time, the present inventor has found that it is possible to immediately oxidize the metal peroxides. However, by first generating metal hydroxide in water using a reducing agent such as sodium sulfite or hydrazine, and then oxidizing it with an oxidizing agent such as sodium hypochlorite under alkaline conditions, metal hydroxide can be easily and sufficiently removed. It has been found that the above object can be achieved by converting it into a peroxide.

(Thus, the present invention is characterized in that a metal oxide is converted into a metal hydroxide using a reducing agent in an aqueous medium, and then oxidized with an oxidizing agent under alkaline conditions to convert it into a metal peroxide. The present invention provides a method for producing a processing agent.

In the present invention, the metal oxide (C in an aqueous medium)
Reducing agents used in the conversion to metal hydroxides include sulfites such as sodium sulfite, potassium sulfite, calcium sulfite, hydrazine or H2, CO,
It is a reducing gas such as CH4, C3H8, etc.

Among these, sulfites such as sodium sulfite and hydrazine are preferred because they have a high reduction reaction rate and are easy to handle.

Further, the pH of the aqueous medium used when producing the metal hydroxide using a reducing agent is usually about 6 to 14, preferably about 7 to 13.

If the pH is lower than the above range, the generated metal peroxide may dissolve, which is not preferable.

The aqueous medium is usually water, but appropriate salts may be present as long as they do not impede the conversion of the metal oxide to its peroxide via the hydroxide.

Moreover, it is preferable to adopt a liquid temperature of 5 to 50° CY.

The obtained metal hydroxide is then oxidized with an oxidizing agent under alkaline conditions to convert it into a metal peroxide.

The oxidizing agent used in the present invention is suitably a hypochlorite such as sodium hypochlorite or calcium hypochlorite.

In addition, upon oxidation with an oxidizing agent, or with a pH of 7.5 to 14
, preferably a pH of about 8 to 13.

If the pH is lower than 7.5, the metal hydroxide to be oxidized will dissolve, the hypochlorite will decompose, and unnecessary chlorine gas will be generated, which is not preferable.

Examples of metal oxides that are raw materials for the metal peroxide used as water treatment agent A in the present invention include nickel, cobalt, copper, mancuff, zinc, cerium, lead, magnesium, aluminum, calcium, barium, strontium, Examples include oxides of metals such as titanium.

These oxides may be, for example, powdered to an appropriate size with or without a binder or granulated, or supported on a suitable carrier such as silica or alumina.

Furthermore, in the present invention, not only the treatment of metal peroxides used as water treatment agents that have been converted into lower oxides, but also the treatment of newly converted metal oxides into metal peroxides as raw materials. It goes without saying that this method can be applied.

The water treatment agent according to the present invention not only treats wastewater that already contains COD, but also collects components such as phenol and formalin contained in gases in an aqueous medium. When the aqueous medium contains COD components, it can also be applied to a process in which gas collection and treatment of the COD components are performed simultaneously.

Next, the present invention will be explained by examples.

Example 1 Particle size of 2 mol/l aqueous solution of nickel sulfate 0.2-0.5
The pore volume measured with a mercury intrusion porosimeter is 0.
A siliceous carrier zK9 of 5 CC/r was impregnated, and the resulting solution-impregnated carrier was diluted with 4% caustic soda aqueous solution of 151 for 3
The sample was immersed for an hour to convert nickel sulfate into hydroxide, and then immersed in a 12% sodium hypochlorite aqueous solution of 101 for 3 hours to convert it to nickel hydroxide peroxide.

This was washed with water to sufficiently remove adhering sodium hypochlorite and sodium sulfate, and a treatment agent was obtained.

The active oxygen content of the treatment agent thus obtained (the measurement method will be described later) is 3.6 X I O-'? The treatment agent was 1 oxygen atom/1.

This was placed in a glass reaction tube with an inner diameter of 35u and a length of 2m.
NaC10 was added at a concentration of 180 μ/l to chemical factory wastewater containing methanol and sodium formate as the main CODM components, and 60 μ/l was added from the top of the reaction tube.
- Introduced at a rate of 7 minutes and extracted from the bottom, C, O
The removal rate of DMn was 80%.

The removal rate of CODMn after passing the solution under the above conditions for 30 days was 30%, and the active oxygen content of the treatment agent at this time was 1.
．． The treatment agent was 3×10''4v oxygen atoms/V.

Thus, active oxygen content decreased and COD removal performance decreased. Half of the treatment agent was immersed in a 1% Na2SO3 aqueous solution for 12 hours, and then immersed in a 12% NaC10 aqueous solution for 2 hours. The active oxygen content of the treatment agent was 3.7. After recovering to X I O-' r oxygen atom/1 treatment agent, the same waste water was introduced again into the same reactor at a rate of 307 nl/min and extracted, and the removal rate of CODMn was 82%. .

For comparison, active oxygen was 1.3X as a result of the 30 days of water circulation.
The remaining half of the treatment agent, which became the 10''''4y oxygen atom/V treatment agent, was directly immersed in a 12% NaC10 aqueous solution for 6 hours without any reduction operation with an Na2SO3 aqueous solution, and the active oxygen of the treatment agent was 1. .4 X 10-'? This is an oxygen atom/V treatment agent, and when the same waste water was introduced into the same reactor as above at a rate of 30 yd/min and extracted, the removal rate of CODMn was 35%.

The method for measuring active oxygen in the treatment agent is as follows.

Weigh the processing agent ly correctly and place it in an Erlenmeyer flask with a stopper.
0 ml and add about 257 nl of distilled water.

After adding and dissolving about 21% of KI, add about 10% of 36% acetic acid aqueous solution.
Add rIll and leave in the dark for about 20 minutes.

0. Using IN sodium thiosulfate, the end point of the titration is the point at which the purple color of the starch indicator disappears.

The active oxygen content of the treatment agent is calculated using the following formula.

Xv Active oxygen of treatment agent--X 5 1) Example 2 2 mol/l aqueous solution of nickel sulfate particle size 0.2-0.5
The pore volume measured with a mercury intrusion porosimeter was 0.5.
cc,/r of perilla support 2 was impregnated with 9, and the resulting solution-impregnated support was soaked with 4% caustic soda aqueous solution of 151 with 3
After soaking for 3 hours in a 12% sodium hypochlorite aqueous solution of lOl to convert nickel hydroxide into nickel peroxide, rinse thoroughly with water and use the treatment agent. And so.

The active oxygen content of the obtained treatment agent was 3.4×IF'.

The same amount of this was filled into the same reaction tube as in Example 1, and the same waste water was similarly introduced into the reaction tube and taken out.
The removal rate was 82%.

After the solution was passed under the above conditions for 30 days, the CODMn removal rate was 35%, and the active oxygen content of the treatment agent at this time was 1.5 x 10-'.

The active oxygen content of the treatment agent decreased after immersing half of the treatment agent in a 0.4% hydrazine aqueous solution for 12 hours and then immersing it in a 12% NaC10 aqueous solution for 2 hours. recovered to 3.7 X I O-', and when the same waste water was introduced again into the same reactor at a rate of 30 yd/min and extracted, the removal rate of CODMn was 80
%Met.

For comparison, active oxygen was 1.5 as a result of the 30 days of water circulation.
After immersing the remaining half of the treatment agent, which became X I O-', in a 12% NaC10 aqueous solution for 6 hours without reducing it with a hydrazine aqueous solution, the active oxygen of the treatment agent was 1.
7 x 10""', which was used in the same reactor as above and the same waste water was 3077271! The removal rate of CODMn was 38% when it was introduced and extracted at a rate of 1/min.

Example 3 2 mol/l aqueous solution of cobalt chloride particle size 0.2-0.5
wl1, a silica/alumina carrier with a pore volume of 0.45 CC1/V measured with a mercury intrusion porosimeter was impregnated into two parts, and the resulting solution-impregnated carrier was immersed in a 4% caustic soda aqueous solution of 151 for 3 hours to form a cobalt chloride solution. was converted into a hydroxide, and then immersed in a 12% sodium hypochlorite aqueous solution of 1O1 for 3 hours to convert cobalt hydroxide into cobalt peroxide, and then thoroughly washed with water to obtain a treatment agent.

The active oxygen content of the obtained treatment agent was 4. It was OX IF'.

The same amount of this was filled into the same reactor core tube as in Example 1, and the same waste water was introduced into the reaction tube and extracted.
The removal rate was 75%.

After the solution was passed under the above conditions for 30 days, the CODMn removal rate was 30%, and the active oxygen content of the treatment agent at this time was 1.6 x 10-4.

After half of the treatment agent whose active oxygen content decreased and COD removal performance decreased for 12 hours in a 1% Na2SO3 aqueous solution and immersed in a 2% NaClO aqueous solution for 2 hours, the active oxygen content of the treatment agent decreased to 3. When the temperature was restored to 9X10-4, the same waste water was again introduced into the same reactor at a rate of 30-7 minutes, and extracted, the removal rate of CODMn was 77%.

For comparison, active oxygen was 1.6 as a result of the 30 days of water circulation.
The remaining half of the processing agent that became X 10-4 was converted into Na2S.
03 12% NaCl without reduction operation with aqueous solution
The active oxygen content of the treatment agent after being immersed in an aqueous solution for 6 hours was 1.7 X l O-4, and the same waste water was treated using the same reaction apparatus as above. The removal rate of CODMn was 32% when it was introduced and extracted at a rate of 1/min.

Claims (1)

[Scope of Claims] 1. A process in which a metal oxide is converted into a metal hydroxide in an aqueous medium using a reducing agent, and then oxidized with a hypochlorite under alkaline conditions and converted into a metal peroxide. A method for producing a characteristic metal peroxide water treatment agent. 2 Metal oxides include nickel, cobalt, copper, manganese,
The method according to claim 1, wherein the reducing agent is a type of oxide selected from zinc, cerium, lead, magnesium, aluminum, calcium, barium, strontium, and titanium. 3. The reducing agent is sulfite, hydrazine, H21CO ,C
H,, c3n8, the method according to claim 1. 4. The method according to claim 1, wherein the metal oxide is supported on a silica or alumina support.