JP2003010687A - Oxidative decomposition catalyst for organic matter and treatment method for organic matter-containing wastewater using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an oxidative decomposition catalyst for organic matter having strong activity and a treatment method for organic matter-containing wastewater having excellent decomposition and removal effects of organic matter in wastewater using the catalyst. SOLUTION: The oxidative decomposition catalyst for organic matter is obtained by supporting Co and Cu on an inorganic porous carrier having ion exchange function so that Cu/(Co+Cu) becomes 0.005-0.3 (weight ratio) by ion exchange supporting treatment. The organic matter-containing wastewater is treated by passing organic matter-containing wastewater through a packed bed of the above catalyst in the coexistence of an oxidizing agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oxidative decomposition catalyst for organic substances and a method for treating organic substance-containing wastewater using the catalyst. More specifically, the present invention relates to a highly active oxidative decomposition catalyst for organic matter and a method for treating organic matter-containing wastewater having an excellent effect of decomposing and removing organic matter in wastewater using the catalyst.

[0002]

2. Description of the Related Art Industrial wastewater discharged from chemical factories, food factories and the like often contains organic substances such as alcohols, fatty acids, polymer compounds, surfactants and solvents. The discharge of wastewater containing organic matter causes environmental pollution.
It is necessary to treat the wastewater to decompose and remove organic substances. As a method for removing organic matter from water, conventionally, activated sludge treatment, oxidation treatment with an oxidizing agent such as hydrogen peroxide or ozone,
Combustion processing is performed. In the activated sludge treatment, operating conditions are likely to be complicated because microorganisms are used, and the treatment effect may be significantly changed due to fluctuations in the quality of wastewater. Further, it is difficult to treat organic components having low biodegradability. Oxidizing treatment with an oxidizing agent is economically disadvantageous in that an attempt is made to completely remove a high-concentration organic substance, since an excessive amount of the oxidizing agent is required in excess of the theoretical amount. The burning process is
It requires a large amount of energy for heating, which is not economically disadvantageous, but also leads to environmental pollution due to an increase in carbon dioxide emission. For this reason, attempts are being made to improve the method for treating wastewater containing organic substances. The present inventors previously disclosed in Japanese Patent Publication No. 58-8307.
As a method for decolorizing and removing organic matter from organic wastewater, the organic wastewater is brought into contact with a catalyst obtained by contacting a carrier with cobalt ions and / or nickel ions and then with a chlorine agent in the presence of a chlorine agent. Suggested a method. This method exerts an excellent effect in treating human waste or organic wastewater obtained by denitrifying treated human waste water, but it has been desired to develop a more active catalyst.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly active oxidative decomposition catalyst for organic matter and a method for treating wastewater containing organic matter, which is excellent in decomposition and removal effect of organic matter in wastewater using the catalyst. It was made.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the coexistence of a small amount of copper in a conventional cobalt-supported catalyst markedly enhances the catalytic activity. It was found that the present invention was completed based on this finding. That is, the present invention is
(1) Co is added to the inorganic porous carrier having an ion exchange function.
And Cu, Cu / (Co + Cu) is 0.005-0.3
The oxidative decomposition catalyst for organic substances according to claim 1, wherein the oxidative decomposition catalyst for organic substances is obtained by carrying out ion-exchange loading treatment so that the (weight ratio) is (2), and the inorganic porous carrier is zeolite or apatite. (3) Oxidative decomposition catalyst of the organic substance according to item 1, which is obtained by converting Co and Cu into oxides after the ion-exchange supporting treatment, and (4) conversion into oxides using hypochlorite. In the coexistence of an oxidant in the packed bed of the oxidative decomposition catalyst of the organic substance according to the third aspect, and (5) the oxidative decomposition catalyst of the organic substance according to the first, second, third or fourth aspect. Disclosed is a method for treating organic matter-containing wastewater, which comprises passing organic matter-containing wastewater.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the catalyst for oxidative decomposition of organic substances of the present invention, cobalt (Co) and copper (Cu) are added to an inorganic porous simple substance having an ion exchange function, and Cu / (Co + Cu) is 0.1.
It is a catalyst obtained by carrying out an ion-exchange supporting treatment so as to be 005 to 0.3 (weight ratio). There is no particular limitation on the inorganic porous carrier having an ion exchange function used in the present invention, for example,
Aluminosilicate compounds such as zeolite, apatite, zirconia, zirconium phosphate oxide (ZrO ₂
· P ₂ O _5), zirconium salts, alumina, and the like. Among these, zeolite and apatite can be preferably used. Zeolite is a substance represented by the general formula M _{2 / n} O · Al ₂ O ₃ · xSiO ₂ · yH ₂ O, M is Na, K, Ca or Ba, and n is its valence, x Is 2 to 10 and y is 2 to 7. Zeolites have a structure in which alkali metal, alkaline earth metal, and water molecules are contained in the pores of a three-dimensional network structure formed by (Al, Si) O ₄ tetrahedra sharing the apex, and the cation exchange ability is Have. In the present invention, the zeolite to be used is not particularly limited, and both natural zeolite and synthetic zeolite can be used. For example, faujasite (X type,
Y type), mordenite, ZSM-5, offretite, ferrierite, erionite, A type, chabazite, clinoptilolite and the like. Among these, faujasite (X type, Y type), mordenite,
Type A and clinoptilolite can be particularly preferably used. Zeolite has an ion exchange capacity of 4.7 m for type X
eq / g, Y type 3.7 meq / g, mordenite 2.3 meq
/ G, A type is 5.5 meq / g, clinoptilolite is 2.
It is 2 meq / g. Apatite is a hexagonal mineral represented by the general formula A ₅ (XO ₄ ) ₃ Z _q , which is also called apatite, where A is Ca or Pb, X is As, P or V, Z is F,
Cl or OH. The apatite used in the present invention is not particularly limited, and any of fluoroapatite, chlorapatite, hydroxyapatite and carbonate apatite can be used.

In the present invention, there is no particular limitation on the method of carrying out the ion exchange supporting treatment of cobalt and copper on the inorganic porous carrier having an ion exchange function. For example, the inorganic porous carrier is an aqueous solution containing a cobalt salt and a copper salt. Alternatively, an aqueous solution containing a cobalt salt and a copper salt may be passed through a column packed with an inorganic porous carrier in a transient or circulating manner. Examples of the cobalt salt include cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt acetate. As the copper salt, for example,
Examples thereof include copper chloride, copper sulfate, copper nitrate and copper acetate. It is preferable that the inorganic porous carrier carrying the ion exchange of cobalt and copper is washed with water to remove the attached cobalt and copper by contacting with an aqueous solution containing a cobalt salt and a copper salt. In the present invention, the ratio of cobalt (Co) and copper (Cu) to be ion-exchanged and supported on the inorganic porous carrier is 0.0 / Cu / (Co + Cu) (weight ratio).
05-0.3, and more preferably 0.01-0.25.
And more preferably 0.02 to 0.2. Cu
If / (Co + Cu) (weight ratio) is less than 0.005 or more than 0.3, the catalytic activity of the organic compound as an oxidative decomposition catalyst may decrease. The ratio of cobalt and copper to be ion-exchanged and supported on the inorganic porous carrier is determined based on the relationship between the solid surface of the inorganic porous carrier and the exchange equilibrium of metal ions in the aqueous solution, that is, the solid-liquid partition coefficient.
It is preferable to experimentally determine the cobalt concentration and the copper concentration of the aqueous solution so as to obtain (Co + Cu).
In the present invention, the amount of cobalt and copper to be ion-exchanged and supported on the inorganic porous carrier is preferably 1% by weight or more, and more preferably 2% by weight or more, as the total amount of cobalt and copper supported. If the total supported amount of cobalt and copper is less than 1% by weight, the catalytic activity of the organic compound as an oxidative decomposition catalyst may be insufficient. The upper limit of the total supported amount of cobalt and copper to be carried by ion exchange is determined by the ion exchange capacity of the inorganic porous carrier used, but normally the supported amount is preferably less than 90% of the ion exchange capacity. The ion exchange operation may be complicated in order to make the total supported amount of cobalt and copper 90% or more of the ion exchange capacity of the inorganic porous carrier.

In the present invention, it is preferable that the inorganic porous carrier is ion-exchanged with cobalt and copper, and then cobalt and copper are converted into oxides. There is no particular limitation on the oxidizing agent used in the conversion treatment of cobalt and copper oxides,
For example, hypochlorite, hypochlorite, chlorine, ozone, hydrogen peroxide, etc. can be mentioned. Among these, hypochlorite can be preferably used because it can be easily handled as an aqueous solution. Examples of the hypochlorite include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, barium hypochlorite and the like. There is no particular limitation on the method for converting the cobalt and copper ion-exchanged and supported on the inorganic porous carrier into the oxide, and for example, the inorganic porous carrier ion-supported on cobalt and copper is immersed in an aqueous solution containing an oxidizing agent. Alternatively, an aqueous solution containing an oxidant can be passed through a column filled with an inorganic porous carrier in which cobalt and copper are ion-exchanged and carried in a transient or circulating manner. In the conversion treatment of cobalt and copper, which are ion-exchanged and supported on the inorganic porous carrier, into the oxide, the inorganic porous carrier, which carries ion-exchanged cobalt and copper, is contacted with an alkaline aqueous solution in advance and then contacted with an aqueous solution of an oxidizing agent. Alternatively, it is preferably contacted with an aqueous solution of an oxidizing agent containing an alkali. It is possible to efficiently proceed the conversion treatment to the oxide by converting cobalt and copper into hydroxide by bringing them into contact with an alkali and further converting into oxide by the action of the oxidizing agent. There is no particular limitation on the degree of conversion treatment of cobalt and copper into oxides. For example, cobalt may be cobalt oxide (II) CoO, cobalt oxide (III) CoO (OH), dicobalt oxide (III) cobalt (I).
I) Co ₃ O ₄ , cobalt peroxide CoO _2, etc. can be converted, and copper is copper (II) Cu ₂ O, copper (III) oxide
It can be converted into CuO, copper peroxide CuO _{2, and the} like. By converting cobalt and copper into oxides and increasing the valences of cobalt and copper, it is possible to enhance the catalytic activity of the organic substance as an oxidative decomposition catalyst.

In the method for treating organic matter-containing wastewater of the present invention, the organic matter-containing wastewater is passed through the packed bed filled with the organic matter oxidative decomposition catalyst in the presence of an oxidizing agent. There is no particular limitation on the organic matter-containing wastewater to which the method of the present invention is applied, for example, alcohol used for rinsing semiconductor substrates for semiconductors, wastewater containing a surfactant, wastewater containing endocrine disrupting chemicals, phenol, etc. Examples thereof include wastewater of a chemical factory that contains it, wastewater of a food factory that contains various organic substances, and wastewater obtained by denitrifying treated human waste water. In the method of the present invention, the oxidizing agent to be coexisted with the organic matter-containing wastewater is not particularly limited, and examples thereof include hypochlorite, hypochlorite, chlorine, ozone, hydrogen peroxide and the like. Among these, hypochlorite can be preferably used because it can be easily handled as an aqueous solution. Examples of the hypochlorite include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, barium hypochlorite and the like. The amount of the oxidant to coexist is preferably 1.1 to 3 times by weight, and preferably 1.2 to 2.5 times by weight, the theoretical amount necessary for oxidatively decomposing the organic matter contained in the waste water. Is more preferable. In the method of the present invention, there is no particular limitation on the method of passing the organic substance-containing wastewater in the coexistence of an oxidant into the packed bed of the organic substance oxidative decomposition catalyst, and for example, either an upward flow or a downward flow is possible. In the case of upward flow, the catalyst packed bed can be a fixed bed or a fluidized bed. There is no particular limitation on the rate of passage of the organic matter-containing wastewater to the catalyst packed bed, but the space velocity at the time of water passage can be set according to the target water quality of the treated water, and the space velocity is generally 0.5-1.
It is preferably 0h ^-1 , more preferably ¹ to 7h ^-1 . The oxidative decomposition catalyst of an organic substance of the present invention is a catalyst in which a small amount of copper is allowed to coexist in a cobalt catalyst, and has a strong catalytic activity against the oxidative decomposition of an organic substance due to the cocatalyst effect of copper. By passing the organic substance-containing wastewater in the coexistence of the oxidizing agent into the packed column of the organic substance oxidative decomposition catalyst of the present invention, the organic substances in the wastewater can be effectively oxidatively decomposed and removed.

[0009]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Comparative Example 1 (Preparation of catalyst) 500 g of clinoptilolite natural zeolite having a particle size of 0.5 to 1.0 mm was added to a 7.8 wt% cobalt sulfate aqueous solution 70.
After immersing in 0 mL for 17 hours to carry out ion exchange loading treatment,
The liquid is poured out by decantation, and then 5 parts of pure water are added.
The cobalt adhering to the zeolite surface was completely washed away by washing 3 times with 00 mL. The supported amount of cobalt was 2.5% by weight. Then, the zeolite supporting cobalt by this ion exchange supporting treatment is immersed in 500 mL of an aqueous solution containing 6.3% by weight of sodium hypochlorite and 3.7% by weight of sodium hydroxide for 5 hours to convert cobalt into an oxide. Then, after activation treatment, it was washed with 10 L of pure water. Examples 1 to 5 (Preparation of catalyst) In the same manner as in Comparative Example 1 except that an aqueous solution containing cobalt sulfate and copper sulfate was used instead of the cobalt sulfate aqueous solution,
Five kinds of catalysts having a total supported amount of cobalt and copper of 2.5% by weight and a ratio of copper to the total amount of cobalt and copper of 0.02 to 0.2 (weight ratio) were prepared. Comparative Examples 2 to 3 (Preparation of catalyst) In the same manner as in Comparative Example 1 except that an aqueous solution containing cobalt sulfate and copper sulfate was used instead of the cobalt sulfate aqueous solution,
Two kinds of catalysts having a total supported amount of cobalt and copper of 2.5% by weight and a ratio of copper to the total of cobalt and copper of 0.4 or 0.6 (weight ratio) were prepared. Comparative Example 4 (Catalyst performance evaluation test) A catalyst performance evaluation test was performed using synthetic wastewater prepared by dissolving 25 mg / L of phenol in pure water. Oxygen consumption (CO
D _Mn ) is 44.0 mg / L, and organic carbon (TOC)
Is 19.1 mg / L. An acrylic resin column having an inner diameter of 30 mm was packed with 250 mL of the catalyst prepared in Comparative Example 1 (packing height 350 mm), and sodium hypochlorite was added to the above-mentioned synthetic wastewater so as to be 500 mg / L, and the flow rate was 1 , 3
An upward flow was performed at 75 mL / h (SV 5.5 h ^-1 ). The treated water was sampled 5 hours after the passage of the liquid, and the water quality was analyzed.
The treated water had COD _Mn of 12.0 mg / L and TOC of 11.9, and the removal rates were 73% and 37%, respectively. Example 6 (Catalyst performance evaluation test) The catalyst prepared in Example 1 was subjected to a performance evaluation test in the same manner as in Comparative Example 1. COD _Mn of treated water is 8.7 m
The g / L and TOC were 10.4 mg / L, and the removal rates were 80% and 45%, respectively. Examples 7 to 10 (Catalyst performance evaluation test) With respect to the catalysts prepared in Examples 2 to 5, a performance evaluation test was performed in the same manner as in Comparative Example 1. Comparative Examples 5-6 Performance evaluation tests were conducted on the catalysts prepared in Comparative Examples 2-3 in the same manner as in Comparative Example 1. The results of Examples 6 to 10 and Comparative Examples 4 to 6 are shown in Table 1. In addition, Cu / (C
The relationship between (o + Cu) (weight ratio) and COD _Mn of treated water is shown in FIG.

[0010]

[Table 1]

As shown in FIG. 1, when the cobalt-only supported oxidative decomposition catalyst was used, COD _{Mn of} 44.0 mg /
COD _Mn of treated water obtained by treating L synthetic wastewater is 12.0 mg
The COD _Mn of the treated water sharply decreases by coexisting a small amount of copper, while it decreases only to / L.
Estimated from the curve in the drawing, the COD _Mn of the treated water is 10 mg / L when Cu / (Co + Cu) is about 0.005, and the COD of the treated water is C when Cu / (Co + Cu) is about 0.05.
The minimum value of OD _Mn is 7.6 mg / L, and Cu / (Co + C
When u) exceeds 0.05, the COD _Mn of the treated water gradually rises as the amount of copper increases, and when Cu / (Co + Cu) is about 0.3, the COD _Mn of the treated water becomes 10 mg / L. .

[0012]

The oxidative decomposition catalyst of an organic substance of the present invention is a catalyst in which a small amount of copper is made to coexist in a cobalt catalyst, and has a strong catalytic activity against the oxidative decomposition of an organic substance due to the cocatalyst effect of copper. . By passing the organic substance-containing wastewater in the coexistence of the oxidizing agent into the packed column of the organic substance oxidative decomposition catalyst of the present invention, the organic substances in the wastewater can be effectively oxidatively decomposed and removed.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between Cu / (Co + Cu) (weight ratio) and COD _Mn of treated water.

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Claims (5)

[Claims] 1. An inorganic porous carrier having an ion exchange function, Co and Cu, and Cu / (Co + Cu) 0.005.
An oxidative decomposition catalyst for an organic substance, characterized by being subjected to an ion-exchange supporting treatment so as to have a weight ratio of up to 0.3 (weight ratio). 2. The catalyst for oxidative decomposition of organic substances according to claim 1, wherein the inorganic porous carrier is zeolite or apatite. 3. The catalyst for oxidative decomposition of organic substances according to claim 1, which is obtained by converting Co and Cu into oxides after the ion-exchange supporting process. 4. The oxidative decomposition catalyst for an organic substance according to claim 3, wherein the conversion to an oxide is carried out using hypochlorite. 5. An organic matter containing an organic matter-containing wastewater in the presence of an oxidizing agent through a packed bed of the organic matter oxidative decomposition catalyst according to claim 1, claim 2, claim 3 or claim 4. Treatment method of contained wastewater.