JP4880572B2 - Method for treating ethylene glycols - Google Patents

Description

  The present invention relates to a method for treating ethylene glycols. That is, the present invention relates to a treatment method for oxidizing and decomposing ethylene glycol, diethylene glycol or the like contained in industrial waste water or the like based on the Fenton method.

《Technical background》
Ethylene glycol, diethylene glycol, etc. consist of viscous colorless liquids, are easily soluble in polar solvents such as water, are used as solvents, antifreezes, softeners, lubricants, etc., and are also used as raw materials for synthetic fibers and plastics .
In addition to being a hardly decomposable organic compound, it has been pointed out to be harmful to the human body. From the viewpoint of preventing water pollution, establishment of purification technology for industrial wastewater containing ethylene glycol is desired. It is rare.

<Conventional technology>
Conventionally, for example, the following can be considered as a purification treatment technique for industrial wastewater containing such ethylene glycols.
a. Microbial treatment method: Ethylene glycol is biologically decomposed using microorganisms, and the generated excess sludge is treated.
b. Catalytic method: Ethylene glycol is decarboxylated to methane, carbon dioxide, etc. using platinum or other platinum group catalysts.
c. Activated carbon adsorption + coagulation sedimentation treatment method: After ethylene glycol is adsorbed on powdered activated carbon, it is degraded to an inorganic state and coagulated, precipitated, and separated as a compound with iron salt or the like.
d. Fenton treatment method (conventional method): Ethylene glycols are oxidized and decomposed by OH radicals generated by hydrogen peroxide and iron salt, that is, divalent iron ions, and thus aggregate, precipitate and separate.
e. In addition, UV / ozone treatment methods (photocatalyst and ozone are irradiated with ultraviolet rays to generate OH radicals) and RO membrane treatment methods are also conceivable.

《Information on prior art documents》
Examples of this type of conventional example include those disclosed in the following Patent Documents 1, 2, and 3. Patent Document 1 relates to a microbial treatment method, Patent Document 2 relates to a catalyst method, and Patent Document 3 relates to a Fenton treatment method.
JP 2002-210489 A Japanese Patent Laid-Open No. 7-232178 JP 2006-239507 A

By the way, the following problems have been pointed out with regard to such conventional purification techniques for industrial wastewater containing ethylene glycol.
<First problem>
First, the conventional Fenton treatment method has been pointed out that the treatment performance is poor and the running cost (chemical use cost) increases.
For example, hydrogen peroxide, which is a generation source of OH radicals, is easily wasted during the treatment, and a large amount of hydrogen peroxide has been added in advance. That is, hydrogen peroxide is easily decomposed into water and oxygen without generating OH radicals, and hydrogen peroxide is excessively added to cover this, resulting in poor efficiency. This problem becomes a major bottleneck when the Fenton treatment method is scaled up and applied to a large-scale treatment such as industrial wastewater and a large-capacity treatment.

<< Second problem >>
Secondly, the conventional Fenton treatment method has been pointed out that the post-treatment is also costly.
Since hydrogen peroxide is excessively added as described above, the residual content of hydrogen peroxide is high in the industrial waste water after the ethylene glycol is oxidized, decomposed and separated, and the ion concentration becomes very high. Therefore, in order to discharge as purified water, it is necessary to add a large amount of a neutralizing agent such as catalase as a post-treatment, which further increases the cost of using the chemical. This is also a big bottleneck when applying scale-up to large-scale processing and large-capacity processing.

《Third problem》
Thirdly, the conventional Fenton treatment method has also been pointed out that it is not easy to control the amount of chemical added.
That is, it was not easy to respond to fluctuations in the quality of supplied industrial wastewater and the like and to changes in the content of ethylene glycol, that is, to control the amount of hydrogen peroxide and iron salt added. Hydrogen peroxide and iron salt should be added in appropriate amounts, but the rate of addition has not been established, and they tend to be too little or too much. This is also a bottleneck in applying scale-up to large-scale processing and large-capacity processing.

《Fourth problem》
Fourthly, on the other hand, the following problems have been pointed out regarding the microbial treatment method, catalyst method, activated carbon adsorption + coagulation sedimentation treatment method, UV / ozone treatment method, RO membrane treatment method, etc. It was a bottleneck in applying scale-up to processing.
a. Microbial treatment method: Control of the environment of microorganisms is not easy, and complicated and delicate technology is required. Therefore, there are difficulties in stability of the treatment, taking up installation space and increasing the equipment cost. There was a problem that processing cost also increased.
b. Catalytic method: Since expensive platinum and other platinum group metals are used as a catalyst, there is a problem that the cost burden becomes excessive.
c. Activated carbon adsorption + coagulation sedimentation treatment method: It is difficult to reduce the processing capacity due to activated carbon breakthrough, and there are problems in processing stability, activated carbon replacement cost, installation space, equipment cost, etc.
d. UV / ozone treatment method: There were problems with poor OH radical production efficiency, equipment cost, power waste cost, UV lamp degradation, and the like.
e. RO membrane treatment method: In the membrane treatment, there is no change in the components of the ethylene glycol itself, and the treatment may become unstable due to clogging.

<< About the present invention >>
The processing method of ethylene glycols of this invention is made | formed in order to solve the subject of the said prior art example in view of such a situation.
In the present invention, first, OH radicals are efficiently generated, and the running cost is excellent. Second, the post-processing cost is excellent. Third, the chemical addition amount is easily controlled. Another object of the present invention is to propose a method for treating ethylene glycol, which is excellent in processing stability, initial cost and the like.

<About Claim>
The technical means of the present invention for solving such a problem is as follows.
The ethylene glycol treatment method according to claim 1 oxidizes and decomposes ethylene glycol contained in the water to be treated based on the treatment process of the Fenton method. Then, hydrogen peroxide, a divalent iron ion solution, and a pH adjuster are added to the water to be treated containing ethylene glycol.

Then, the entire amount of hydrogen peroxide is added to the treatment tank at the beginning of the reaction.
In the treatment tank, the divalent iron ion solution is intermittently added repeatedly by repeating a plurality of cycles after the addition of hydrogen peroxide, so that the OH radicals generated below return to water and are wasted. It works to avoid.
As for the pH adjuster, an acid pH adjuster is first added to the water to be treated supplied to the treatment tank in the pH adjustment tank, and divalent iron is added in the treatment tank after the addition of hydrogen peroxide. An alkaline pH adjuster is added each time the ionic solution is added in a divided manner, so that the water to be treated is maintained at a weak acidity of pH 3 to pH 5, and the reaction in which hydrogen peroxide is decomposed and wasted into water and oxygen is suppressed. It works as much as possible.

As for the addition amount of hydrogen peroxide and divalent iron ions, the required number of moles actually prepared is more calculated based on the theoretical reaction value based on the reaction formula.
First, from the specific content of ethylene glycol contained in the water to be treated, the number of moles of the theoretical reaction value of OH radical is obtained as a reference, and then the actual required number of moles of OH radical is obtained based on this standard. From the required number of moles of OH radicals, the theoretical number of moles of reaction of hydrogen peroxide and divalent iron ions, which are OH radical products, is obtained as a reference, and The required number of moles of hydrogen peroxide and divalent iron ions that are actually prepared is calculated from this criterion.
The addition timing of hydrogen peroxide and divalent iron ions is when hydrogen peroxide is used up and hydrogen peroxide is exhausted from the water to be treated in the treatment tank. This is a time when divalent iron ions disappear from the water to be treated in the treatment tank after the previously added portion is used up.

As for the OH radical production reaction, hydrogen peroxide is reduced with divalent iron ions each time it is added in a divided manner, and in addition to the Fenton main reaction, in which OH radicals are produced, the hydrogen peroxide is further reduced. The generated hydroxide ions are oxidized by trivalent iron ions generated by the oxidation reaction of divalent iron ions to generate OH radicals, and the generated OH radicals are further covered. The reaction of reacting with the water of the treated water to generate new OH radicals and water is repeated in a chain, and the trivalent iron ions generated by the oxidation reaction of the divalent iron ions The reaction of reacting with hydrogen oxide to generate at least new OH radicals is repeated in a chain, and the generation of OH radicals ends when hydrogen peroxide is exhausted in the treatment tank.
Therefore, ethylene glycol or diethylene glycol contained in the water to be treated is oxidized and decomposed by the OH radicals thus generated, ethylene glycol becomes water and carbon dioxide, diethylene glycol becomes water, carbon dioxide and oxygen, Each is characterized by being mineralized.

<About the action>
Since the present invention comprises such means, the following is achieved.
(1) Water to be treated containing ethylene glycols such as ethylene glycol and diethylene glycol is supplied to the treatment apparatus. Then, ethylene glycols are oxidized and decomposed by a treatment method based on the Fenton method.
(2) This treatment apparatus includes a water to be treated supply means, a treatment tank, a post-treatment tank, and the like. The treatment tank is provided with hydrogen peroxide addition means, iron ion addition means, pH adjustment means, and the like.
(3) And the water to be treated is supplied to the treatment tank, but before that, sulfuric acid or the like is added from the pH adjusting means to make it weakly acidic at about pH 4.
(4) In the treatment tank, first, all the hydrogen peroxide is added from the hydrogen peroxide addition means to the water to be treated.
(5) Then, a divalent iron ion solution is dividedly added from the iron ion adding means, and for each divided addition, caustic soda or the like is added from the pH adjusting means, and the weak acidity of the water to be treated is maintained. .
(6) Now, in the treatment tank, hydrogen peroxide generates OH radicals using divalent iron ions as a catalyst. In this production reaction, since iron ions are added in portions, there is no possibility of a reaction that wastes OH radicals and iron ions. Further, since the atmosphere is weakly acidic, the catalytic function of iron ions is promoted, so that hydrogen peroxide is not decomposed or wasted into water and oxygen.
(7) OH radicals can also be generated by the reaction of trivalent iron ions and hydroxide ions generated by the above reaction.
(8) The OH radical is further reacted with the hydrogen peroxide produced by the above reaction by reacting the OH radical produced by the above reaction with the water to be treated. By doing so, each of them is repeatedly generated in a chain and newly generated.
(9) Now, in the treatment tank, ethylene glycols contained in the water to be treated are oxidized and decomposed by the strong oxidizing power of the OH radicals generated in this way, and thus low molecules such as water and carbon dioxide. Mineralized into compounds.
(10) Then, the water to be treated is drained outside through the post-treatment tank.
(11) In this processing method, the addition amount of the Fenton reagent or the like can be easily calculated from the reaction theoretical value, the configuration is relatively simple, and stable processing is possible.
(12) Now, the treatment method of the present invention exhibits the following effects.

<< First effect >>
First, OH radicals are efficiently generated without waste, and the running cost is excellent. That is, in the processing method of the present invention, first, a. OH radicals are efficiently generated by maintaining the weak acidity of the water to be treated, adding all of the hydrogen peroxide, split addition of divalent iron ions, and the like.
b. OH radicals can be chain-repeated and highly efficient by the reaction of trivalent iron ions and hydroxide ions, the reaction of generated OH radicals with water, the reaction of trivalent iron ions with hydrogen peroxide, etc. Is generated.
c. Like this conventional example, hydrogen peroxide is not decomposed and wasted into water and oxygen, and it is not necessary to add an excessive amount of hydrogen peroxide, reducing the cost of using chemicals such as Fenton's reagent. Is done.
With these a, b, and c, in the present invention, ethylene glycols can be easily and reliably oxidized, decomposed, and removed, and can be applied to scale-up, such as full-scale processing, large-scale processing, large-capacity processing, and practical use Easy.

<< Second effect >>
Secondly, the residual content of hydrogen peroxide is very low, reducing the post-treatment costs. That is, in the treatment method of the present invention, OH radicals are efficiently generated as described above, and ethylene glycols are oxidized, decomposed, and removed. The hydrogen peroxide is not excessively added as in the above-described conventional example, and the water to be treated has a small content of hydrogen peroxide after the treatment, and the post-treatment cost by the neutralizing agent is also reduced. .
From this aspect, the present invention also reduces the cost of chemical use, and opens the way to scale-up application to full-scale processing, large-scale processing, large-capacity processing, etc., that is, practical application.

《Third effect》
Thirdly, the chemical addition amount can be easily controlled. That is, in the treatment method of the present invention, the amount of hydrogen peroxide added corresponding to the ethylene glycol content, the amount of divalent iron ions added corresponding to the amount of hydrogen peroxide added, and the addition of a pH adjuster The amount and the like are easily calculated from the theoretical reaction value to obtain the required number of moles.
Therefore, an appropriate amount of chemicals can be added without excess and deficiency, and automatic control of these can be easily performed. For example, unlike the above-described conventional example, a situation in which divalent iron ions remain excessively or insufficient does not occur, and the processing performance is stabilized. From this aspect, the present invention can be easily applied to scale-up, that is, put into practical use for full-scale processing, large-scale processing, large-capacity processing, and the like.

<< 4th effect >>
Fourthly, it is excellent in processing stability and initial cost. That is, in the processing method of the present invention, all the other various problems that have been pointed out with regard to this type of conventional example are all solved.
For example, it is not easy to control the environmental environment of microorganisms, use expensive catalysts such as platinum, need to break through or replace activated carbon, poor OH radical generation efficiency, waste of power, UV lamp deterioration, etc. As well as improving the stability of the system, there is no problem in the installation space, and the equipment cost and other initial costs are reduced. From these aspects, the present invention supports the application of scale-up to full-scale processing, large-scale processing, large-capacity processing, etc., that is, practical use.
As described above, the effects exerted by the present invention are remarkably large, such as all the problems existing in this type of conventional example are solved.

《About drawing》
Hereinafter, the method for treating ethylene glycols of the present invention will be described in detail based on the best mode for carrying out the invention shown in the drawings.
FIG. 1 is a configuration flowchart for explaining the best mode for carrying out the present invention.

<< About ethylene glycols 1 >>
First, the ethylene glycol 1, which is a processing target of the processing method of the present invention, will be described.
Ethylene glycols 1 such as ethylene glycol (C ₂ H ₆ O ₂ ), diethylene glycol (C ₄ H ₁₀ O ₃ ), and polyethylene glycol [HO (CH ₂ CH ₂ O) nH] are more viscous than colorless and transparent liquids. It is a stable substance soluble in water and other polar solvents.
Ethylene glycols 1 are widely used as solvents, antifreezes, lubricants, softeners, etc., and are also used in the production of cosmetics, pharmaceuticals, and the like. Furthermore, raw materials for polyester-based synthetic fibers and polyethylene terephthalate (PET) It is also known as a raw material for plastics. Ethylene glycol, which is a kind of divalent alcohol, is produced from ethylene by a chlorohydrin method or a direct oxidation method. Diethylene glycol and polyethylene glycol are produced by dehydration condensation or polycondensation of ethylene glycol.
Such ethylene glycols 1 are hardly decomposable organic compounds and have recently been pointed out to be harmful to the human body, and from the viewpoint of preventing water pollution, the industry containing ethylene glycols 1 Purification of waste water is important.
In the present invention, the ethylene glycols 1 contained in the water to be treated 3 in such industrial wastewater or the like are treated.

<Outline of processing method>
The treatment method of the present invention oxidizes and decomposes the ethylene glycols 1 contained in the water 3 to be treated based on the improved Fenton process.
That is, in the treatment method of the present invention, the water containing ethylene glycol 1 is treated water 3. The ethylene glycols 1 contained in the fenton reagent hydrogen peroxide (H ₂ O ₂ ) and divalent iron ions (Fe ²⁺ ) were used to generate OH radicals (.OH) generated by the Fenton main reaction. Then, it is oxidized and decomposed by OH radicals generated by the incidental, secondary and chain reactions of the Fenton main reaction, and mineralized into low molecular weight compounds such as water and carbon dioxide.
And the processing method of this invention is equipped with the processing tank 4, the to-be-processed water supply means 5, the hydrogen peroxide addition means 6, the iron ion addition means 7, and the pH adjustment means 8 which were attached to this processing tank 4. ing.
Hereinafter, these will be described in detail.

<< About treated water supply means 5 etc. >>
First, the treated water supply means 5 and the like will be described. The treated water supply means 5 supplies the treated water 3 containing the ethylene glycols 1 to the treatment tank 4 as a treatment target.
That is, in the illustrated example, the treated water 3 is introduced into the raw water tank 9 of the treated water supply means 5, and the treated water 3 is supplied to the treated tank 4 via the raw water tank 9 and the pH adjustment tank 10. Is supplied. The treated water 3 introduced into the raw water tank 9 is subjected to pretreatment such as dust sludge removal and biological treatment in advance as necessary. In the pH adjusting tank 10, a pH adjusting agent is added from the attached pH adjusting means 8.
The pH adjusting means 8 adds a pH adjusting agent to the treated water 3 being supplied from the raw water tank 9 of the treated water supply means 5 to the treated tank 4 so as to reduce the treated water 3 to a predetermined weakness. After adjusting to acidity, it is supplied to the treatment tank 4. That is, the treated water 3 from the raw water tank 9 is often pH 6 or more, for example, so that the pH is adjusted to about pH 5 to about 3, typically about pH 4, so that an acid pH such as sulfuric acid is used as a pH adjuster. A modifier is used.
The reason for adjusting the pH in advance in this way is that, as will be described later, in order to ensure that the OH radical production reaction with hydrogen peroxide and divalent iron ions is performed efficiently as expected. is there.
In addition, the said pH adjustment tank 10 is used in the case of the large volume process of the to-be-processed water 3, a continuous process, the process of the high concentration ethylene glycol 1, etc.
The treated water supply means 5 and the like are as described above.

<About hydrogen peroxide addition means 6>
Next, the hydrogen peroxide addition means 6 attached to the processing tank 4 will be described. The hydrogen peroxide addition means 6 adds a total amount of an aqueous solution of hydrogen peroxide (H ₂ O ₂ ) to the treated water 3 in the treatment tank 4 as a Fenton reagent at the beginning of the reaction. Hydrogen peroxide is a source of OH radicals.
The amount of hydrogen peroxide added per reaction depends on the specific content and concentration of the ethylene glycol 1 to be treated contained in the treated water 3, but based on the theoretical reaction value. The actual required amount (necessary number of moles) calculated in a large amount is added all at once at the beginning of the reaction. The next addition is when hydrogen peroxide is exhausted from the water 3 to be treated in the treatment tank 4, that is, at the next reaction, and the whole amount is added in the same manner.
Thus, in this specification, the addition of the total amount means that 100% of the total amount of the drug necessary for the reaction is added all at once.
In this way, the entire amount of hydrogen peroxide is added from the hydrogen peroxide addition means 6.

<< About iron ion addition means 7 >>
Next, the iron ion addition means 7 attached to the processing tank 4 will be described. The iron ion adding means 7 intermittently repeats a plurality of cycles with respect to the water to be treated 3 of the treatment tank 4 after the addition of hydrogen peroxide as described above, thereby supplying a divalent iron ion (Fe ²⁺ ) solution to Fenton. Add in portions as reagents.
That is, substances that generate divalent iron ions in the liquid, such as ferrous sulfate heptahydrate (FeSO ₄ · 7H ₂ O), are typically used as such iron salts, but other anhydrous Salts and hydrated salts such as iron chloride (FeCl ₂ ) and hydrates thereof can also be used. The divalent iron ion functions as a catalyst for the OH radical generation reaction of hydrogen peroxide.
The amount of iron ion added per reaction is calculated based on the theoretical reaction value, but the actual required amount is larger, for example, about 0.5 mole per mole of hydrogen peroxide. .
Moreover, this iron ion is divided and added in multiple times. That is, the necessary amount for one reaction is not added in the whole amount, but is divided into about 3 to 7 times, for example, 5 times, and is added sequentially. As for the addition timing for each time, the next time is added at the stage where the previous addition is gone. Thus, in this specification, divided addition means that the amount of drug necessary for the reaction is added in multiple portions.

The reason why the divalent iron ions are added separately is as follows: a, b, c. First a. If the total amount is added, in the chemical reaction to be described later, the OH radical is wasted at the same time as the intended positive reaction from the original system using hydrogen peroxide as a reactant to the production system using OH radical as a product. Reaction is likely to occur. That is, a reaction in which surplus OH radicals return to water easily occurs, loss occurs, and iron ions used for generating OH radicals are wasted. On the other hand, when the addition is divided, such a reaction is suppressed and the waste of iron ions is eliminated.
B. OH radicals have a very short reaction time due to their intense reaction, and have a very short life. When the total amount is added in a divided manner, OH radicals are generated each time, and the corner of the treated water 3 in the treatment tank 4 is generated. I will come across. Therefore, the oxidation and decomposition of ethylene glycols 1 can be ensured, made efficient and expedited accordingly.
C. When the addition is divided, the remaining hydrogen peroxide is smaller than the total addition, and accordingly, the post-treatment cost by the neutralizing agent is reduced accordingly.
In this way, divalent iron ions and the like are dividedly added from the iron ion adding means 7.

<About pH adjusting means 8>
Next, the pH adjusting means 8 attached to the processing tank 4 will be described. The pH adjusting means 8 adjusts the pH of the water to be treated 3 before being supplied from the water to be treated supplying means 5 to the treatment tank 4 and the water to be treated 3 after being supplied to the treatment tank 4 as described above. An agent is added to maintain the water to be treated 3 at a weak acidity of about pH 4, for example.
That is, the pH adjusting means 8 adds an acid pH adjuster such as sulfuric acid (H ₂ SO ₄ ) before the addition of hydrogen peroxide, and after the addition of hydrogen peroxide, An alkaline pH adjuster such as caustic soda (NaOH) is added.

The reasons for maintaining the water to be treated 3 at about pH 3 to about pH 5 typically about pH 4 are as follows: a, b, c.
First a. As will be described later, it functions to suppress a wasteful decomposition reaction of hydrogen peroxide into water and oxygen that inhibits the intended reaction. With this, b. It functions to promote electron donation of divalent iron ions to hydrogen peroxide. C. It functions to promote and ensure the incidental, secondary, and chain-repeated OH radical generation reactions described below. With these a, b, and c, generation of OH radicals proceeds efficiently.
On the other hand, first, the treated water 3 from the raw water tank 9 of the treated water supply means 5 is often, for example, pH 6 or higher, and therefore, as described above, in the pH adjusting tank 10, Sulfuric acid is added to adjust the pH to about 4, for example.
Then, after the fact, when divalent iron ions are added in the treatment tank 4, the pH of the water to be treated 3 is lowered to, for example, about 2.8 and the acidity is excessively increased. For each divided addition, for example, caustic soda is added to adjust the pH of the water to be treated 3 to about pH 4, for example.
The pH adjusting means 8 is as described above.

<< Reaction in Treatment Tank 4 (OH Radical Generation: Part 1) >>
Next, the chemical reaction (generation of OH radicals: part 1) in the treatment tank 4 will be described. In this treatment method, first, in the treatment tank 4, the water to be treated 3 is stirred and flowed down, and the added hydrogen peroxide is reduced with divalent iron ions added as a catalyst. OH radicals are generated.
The generation of such OH radicals will be further described in detail. In the treatment tank 4, OH radicals are generated based on the following chemical formulas 1 and 2 (chemical formula 3). This is the Fenton main reaction.

These will be further described in detail. In this Fenton main reaction, the divalent iron ions (Fe ²⁺ ) sequentially added from the iron ion addition means 7 in the reaction formula of the above chemical formula 1 maintain the treated water 3 in a weakly acidic atmosphere having a pH of about 4, for example. Therefore, as a catalyst, electrons (e ⁻ ) are sequentially donated to the hydrogen peroxide (H ₂ O ₂ ) of the above reaction formula 2 as a catalyst, and the self oxidizes to trivalent iron ions ( Fe ³⁺ ).
Therefore, in the reaction formula of Chemical Formula 2, all of the hydrogen peroxide initially added from the hydrogen peroxide addition means 6 is sequentially supplied with electrons based on the chemical formula of Chemical Formula 1, and in each case, OH radical (.OH) And hydroxide ions (OH ⁻ ) are produced. When the reaction formulas of Chemical Formula 1 and Chemical Formula 2 are synthesized together, the reaction formula of Chemical Formula 3 is obtained.
By the way, in such a reaction, since the to-be-processed water 3 is maintained in the weakly acidic atmosphere as mentioned above, it is suppressed that hydrogen peroxide is decomposed | disassembled into water and oxygen, and wasted. On the other hand, if it is not maintained in a weakly acidic atmosphere, hydrogen peroxide becomes water molecules (H ₂ O) while generating oxygen (O) in the nascent stage according to the following reaction formula 4; The reaction formula of Chemical Formula 2 (Chemical Formula 3) is wasted without generating OH radicals. It should be noted that oxygen in this nascent stage is out of the system as oxygen molecules (O ₂ ) when there is no oxidation target.
In the treatment tank 4, first, OH radicals are generated by such a Fenton main reaction.

<< Reaction in treatment tank 4 (generation of OH radicals: 2) >>
Next, the chemical reaction (generation of OH radical: part 2) in the treatment tank 4 will be described. Secondly, in the treatment tank 4, OH radicals (.OH) can be generated also by the following reaction formulas 5 and 6.
That is, in the treatment tank 4, first of all, OH radicals are generated by the Fenton main reaction in the reaction formula of the chemical formula 3 (Chemical formula 1, Chemical formula 2). OH radicals can also be generated incidentally, secondaryly, or chained by the reaction formula of ## STR5 ##

This will be further described in detail. In the treatment tank 4, the hydroxide ions (OH ⁻ ) generated by the reduction reaction of hydrogen peroxide are converted into trivalent iron ions (Fe ³⁺ ) generated by the oxidation reaction of divalent iron ions. Oxidized to generate OH radicals (.OH).
That is, the trivalent iron ion generated by the chemical formula 1 is converted into an electron (e ⁻ ) from the hydroxide ion generated by the chemical formula 2 according to the chemical formula 5 and chemical formula 6 above. OH radicals are generated, and they are reduced to divalent iron ions and returned.
In this way, when not only the reaction formula of Chemical Formula 3 (Chemical Formula 1, Chemical Formula 2) but also the chemical formulas of Chemical Formula 5 and Chemical Formula 6 occur in a chain-balanced manner, OH radicals are generated more efficiently. The
Secondly, in the treatment tank 4, OH radicals can be generated by such a reaction.

<< Reaction in Treatment Tank 4 (Generation of OH radical: Part 3) >>
Next, the chemical reaction (generation of OH radicals: part 3) in the treatment tank 4 will be described. In the treatment tank 4, in addition to the first and second described above, new OH radicals are generated incidentally, secondary, and chained by the third reaction.
That is, the OH radicals generated by the reaction formulas of Chemical Formula 3 (Chemical Formula 1, Chemical Formula 2) and Chemical Formula 5 and Chemical Formula 6 react with the water of the water 3 to be treated, and new OH radicals and water are converted. The reaction to be generated is repeated in a chain according to the following reaction formulas 7 and 8.

These will be further described in detail. First, in a neutral to alkaline atmosphere, OH radicals extract hydrogen atoms from water molecules and oxidize them to generate oxygen molecules, and are themselves reduced to water molecules.
On the other hand, in an acidic atmosphere, the OH radical (.OH) withdraws electrons (e ⁻ ) from water molecules (H ₂ O) according to the above reaction formula (7) and converts itself into hydroxide ions (OH ⁻ ). However, this abstraction reaction radically splits and activates water molecules to generate new OH radicals (.OH) and protons (H ⁺ ). The generated hydroxide ions and protons disappear by generating new water (H ₂ O) in the reaction formula of the above formula 8.
Since the water 3 to be treated in the treatment tank 4 is maintained in a weakly acidic atmosphere, new OH radicals are generated in this way. Further, based on the OH radicals thus generated, A series of reactions like this occur in a chain, and the subsequent process is repeated in a chain.
That is, once OH radicals are generated by the reaction formulas such as Chemical Formula 3, etc., OH radicals are obtained semipermanently by a chain reaction afterwards using this as an initiation reaction and reaction initiator. The OH radicals excluding the amount consumed in the oxidation and decomposition processes of ethylene glycols 1 are repeatedly generated and disappeared together with proton chain formation and disappearance. Considering that the OH radical has a very short lifetime, the significance of such repeated generation is great.
Thirdly, in the treatment tank 4, OH radicals are also generated by such a reaction.

<< Reaction in Treatment Tank 4 (OH Radical Generation: Part 4) >>
Next, the chemical reaction (generation of OH radical: part 4) in the treatment tank 4 will be described. In the treatment tank 4, in addition to the first, second, and third described above, OH radicals are newly generated incidentally, subsidiaryly, and continuously by the following reaction.
That is, the reaction in which trivalent iron ions generated by the oxidation reaction of divalent iron ions react with hydrogen peroxide to newly generate OH radicals or the like is represented by the following chemical formulas 9 and 10. The reaction formula (reaction formula of Formula 11) is repeated in a chain.

These will be further described in detail. The trivalent iron ion (Fe ³⁺ ) generated by the reaction formula of Chemical Formula 3 (Chemical Formula 1) reacts with hydrogen peroxide (H ₂ O ₂ ) by the reaction formula of Chemical Formula 9 above. The iron ion is reduced to a divalent iron ion (Fe ²⁺ ), and a superoxide anion (.O ₂ ⁻ ), which is an ion generated by combining oxygen molecules with electrons, is generated.
Then, according to the reaction formula of the above chemical formula 10, this radical superoxide anion can react with hydrogen peroxide to generate an OH radical (.OH). When the reaction formulas of the chemical formulas 9 and 10 are synthesized together, the chemical formula of the chemical formula 11 is obtained.
Thus, as long as the hydrogen peroxide that was the source of OH radical generation in the reaction formula of Chemical Formula 3 (Chemical Formula 2) remains, the OH radicals are oxidized in the process of oxidation and decomposition of ethylene glycols 1. Even if it has been consumed up, as long as hydrogen peroxide remains, new OH radicals are generated in a chain semipermanently based on the hydrogen peroxide. Will continue. Considering that the OH radical has an extremely short lifetime, the significance of such generation continuation is great.
However, in order to ensure that the reaction formula of Chemical Formula 11 (Chemical Formula 9, Chemical Formula 10) occurs, even a weakly acidic atmosphere that does not decompose hydrogen peroxide into water and dissolved oxygen (see the chemical formula of Chemical Formula 4), A pH operation is required, such as adding caustic soda or the like to the water to be treated 3 of the treatment tank 4 by the pH adjusting means 8, and it is necessary to move the pH value to the alkali side.
Furthermore, although the divalent iron ion generated by the reaction formula of Chemical Formula 11 (Chemical Formula 9) lowers the pH, the necessary pH operation is performed in order to coexist with hydrogen peroxide that is stably present in the weakly acidic atmosphere as described above. If carried out, the generation of OH radicals can be expected by the Fenton main reaction of the reaction formula such as Chemical Formula 3 above.
In the treatment tank 3, fourthly, OH radicals are also generated by such a reaction.

<< Reaction in treatment tank 4 (oxidation and decomposition of ethylene glycols 1) >>
Next, oxidation, decomposition, and mineralization of ethylene glycols 1 by OH radicals will be described. In this treatment method, in the treatment tank 4, the ethylene glycols 1 contained in the water to be treated 3 are oxidized and decomposed by the OH radicals generated in the Fenton main reaction and others, thereby becoming mineralized. Is done.
These will be described in more detail. The OH radical, that is, the hydroxy radical (.OH) has a strong oxidizing power as is well known. That is, it has an extremely strong electron (e ⁻ ) deprivation ability, oxidation ability, that is, activation ability and decomposition ability, which is unparalleled as an active oxygen species, and is highly reactive with radicals. In addition, since the reaction is intense, its existence time is a very short-lived chemical species.
Now, the OH radicals dispersed in the water phase oxidize the ethylene glycols 1 contained in the water to be treated 3 and eventually decompose. That is, the OH radical follows the chain process of oxidation with respect to the organic structure of ethylene glycol 1 and the intermediate structure of the decomposition process, for example, targeting the hydrogen atom H. , Molecular bonds are sequentially cut, decomposed, and broken, and finally oxidized, decomposed, and mineralized into inorganic low-molecular compounds. As will be described in detail later, ethylene glycol is oxidized, decomposed and mineralized into water and carbon dioxide, and diethylene glycol is oxidized into water, carbon dioxide and oxygen, respectively.
In the treatment tank 4, the ethylene glycols 1 are thus oxidized, decomposed and mineralized.

<< About the post-treatment tank 11 >>
Next, the post-treatment tank 11 will be described. A post-treatment tank 11 is attached to the treatment tank 4 described above. And the to-be-processed water 3 after ethylene glycol 1 is oxidized and decomposed | disassembled by the above-mentioned to the post-processing tank 11 is discharged | emitted from the processing tank 4, a required process is performed, and it drains outside.
Such a post-treatment tank 11 will be further described in detail. The illustrated post-treatment tank 11 includes a neutralization tank 12, a precipitation tank 13, a coagulation sedimentation tank 14, a filtration tank 15, a pH adjustment tank 16, a treatment water tank 17, and the like in order toward the downstream.
These will be further described in detail. First, the treated water 3 that has been subjected to the oxidation and decomposition treatment of the ethylene glycols 1 is discharged from the treatment tank 4 to the neutralization tank 12 of the post-treatment tank 11.
In the neutralization tank 12, a pH adjuster such as caustic soda is added to the water 3 to be treated, and the pH is adjusted to the optimum value for the inorganic flocculant. When hydrogen peroxide remains even in the treated water 3, a neutralizing agent such as catalase is added in order to avoid water pollution.
Next, in the sedimentation tank 13, the colloidal complex with iron contained as a residue in the water to be treated 3 flowing in from the neutralization layer 12 is solid-liquid separated and precipitated and removed in the lower part.
In the next coagulation sedimentation tank 14, for example, polyaluminum chloride (PAC, Al ₂ (OH) _n Cl _6-n ) or chloride chloride is used as the inorganic coagulant for the treated water 3 flowing from the upper part of the sedimentation tank 13. Diiron (FeCl ₃ ) is added and stirred. Thus, the colloidal complex remaining in the water to be treated 3 without being precipitated in the settling tank 13 is agglomerated and solid-liquid separated to be precipitated and removed.
In addition, when the residual amount of trivalent iron ions (Fe ³⁺ ) generated by the Fenton method in the water to be treated 3 is large, the iron ions (Fe ³⁺ ) function as an inorganic flocculant. The addition of is unnecessary.
If necessary, a storage sedimentation tank is provided next to the aggregation sedimentation tank 14, and for example, an anion is added as a polymer flocculant so that the colloidal complex is further agglomerated, blocked, and solid-liquid separated. , And precipitation and removal may be attempted.
Then, the water to be treated 3 sequentially passes through the filtration tank 15, the pH adjustment tank 16, and the treated water tank 17. Thus, the treated water 3 is further purified, adjusted to a pH value suitable for external drainage, and then drained from the treated water tank 17 to be discharged.
The post-treatment tank 11 is as described above.

《Action etc.》
The method for treating ethylene glycols 1 of the present invention is configured as described above. Therefore, it becomes as follows.
(1) The treated water 3 containing ethylene glycols 1 such as ethylene glycol, diethylene glycol, and polyethylene glycol is supplied to the treatment device 2.
Then, the treatment apparatus 2 is used to purify the treated water 3 by oxidizing and decomposing the ethylene glycols 1 by a treatment method based on the treatment process of the Fenton method.

(2) And this processing apparatus 2 is equipped with the raw | natural water tank 9, the pH adjustment tank 10, the processing tank 4, the post-processing tank 11, etc. of the to-be-processed water supply means 5 in order.
A pH adjusting means 8 is attached to the pH adjusting tank 10. The treatment tank 4 is provided with hydrogen peroxide adding means 6, iron ion adding means 7, pH adjusting means 8, and the like.

  (3) The treated water 3 is supplied from the raw water tank 9 of the treated water supply means 5 to the treatment tank 4. In addition, before the water 3 to be treated is supplied to the treatment tank 4, an acid pH adjuster such as sulfuric acid is added from the pH adjustment unit 8 in the pH adjustment tank 10, so that the acidity of pH 3 to pH 5 such as about pH 4 is weakly acidic. It is said.

  (4) First, an aqueous solution of hydrogen peroxide is added from the hydrogen peroxide addition means 6 to the water to be treated 3 supplied to the treatment tank 4. The total amount of hydrogen peroxide is added at the beginning of the reaction.

(5) In the treatment tank 4, after the hydrogen peroxide is added in this way, a divalent iron ion solution is added from the iron ion addition means 7 to the water to be treated 3. This addition is performed by repeating a plurality of cycles intermittently divided into a plurality of times by divided addition during the reaction after the addition of hydrogen peroxide.
Further, for each divided addition of iron ions, an alkaline pH adjusting agent such as caustic soda is added from the pH adjusting means 8 so that the water to be treated 3 always maintains a weak acidity of about pH 4, for example. That is, the water to be treated 3 is adjusted to an optimum pH for generating OH radicals.

(6) Now, in the treatment tank 4, OH radicals are generated based on the following first, second, third and fourth reactions.
First, the total amount of hydrogen peroxide added as described above is reduced by divalent iron ions added in portions as a catalyst, and OH radicals are generated each time the addition is performed.
That is, by the Fenton main reaction in the reaction formula of Chemical Formula 3 (Chemical Formula 1, Chemical Formula 2), the divalent iron ion donated an electron to hydrogen peroxide to become a trivalent iron ion, and the electron was donated. Hydrogen peroxide generates OH radicals.
The generation of OH radicals is carried out efficiently without waste, since there is no risk of wasteful reaction of OH radicals and divalent iron ions because divalent iron ions are added in portions. Is done.
In addition to this, the generation of OH radicals is more efficiently and reliably performed by being maintained in a weakly acidic atmosphere having a pH of about 4. That is, under the weak acid atmosphere, first, electron donation of divalent iron ions is promoted, and further, hydrogen peroxide is decomposed into water and oxygen by the reaction formula (4) and is wasted. Suppressed and avoided, generating full-capacity OH radicals.

(7) Second, OH radicals are hydroxylated by a reduction reaction of hydrogen peroxide with trivalent iron ions generated by an oxidation reaction of divalent iron ions in the treatment tank 4. Ions can also be generated by oxidation.
That is, OH radicals can be generated by the reaction formulas of Chemical Formula 5 and Chemical Formula 6 based on the trivalent iron ions and hydroxide ions generated by the reaction formula of Chemical Formula 3 (Chemical Formula 1, Chemical Formula 2). From this aspect, OH radicals are efficiently generated. The OH radicals are also generated in a chain every time iron ions are dividedly added.

(8) OH radicals are also generated by the following third and fourth. That is, other than the Fenton main reaction of (6) above, it continues to be efficiently generated by incidental, secondary, and chain reactions.
Third, OH radicals generated by the reaction formulas of the chemical formula 3 react with the water of the water 3 to be treated according to the chemical formulas of the chemical formulas 7 and 8, so that new OH radicals are repeated in a chain. Generated.
Fourthly, the trivalent iron ion generated by the reaction formula of Chemical Formula 3 (Chemical Formula 1) and hydrogen peroxide react by the reaction formula of Chemical Formula 11 (Chemical Formula 9 and Chemical Formula 10). New OH radicals are repeatedly generated in a chain.
Note that the generation of the first, second, third, and fourth OH radicals ends when the hydrogen peroxide of the Fenton reagent is exhausted in the processing tank 4.

(9) Now, the OH radicals thus generated have a very strong oxidizing power. Therefore, in the treatment tank 4, ethylene glycols 1 such as ethylene glycol, diethylene glycol, polyethylene glycol and the like contained in the water to be treated 3 are oxidized and decomposed by the OH radicals to be mineralized into low molecular compounds. End up.
For example, ethylene glycol is mineralized to water and carbon dioxide, and diethylene glycol is mineralized to water, carbon dioxide, and oxygen.

(10) In the water 3 to be treated, the ethylene glycol 1 contained therein is mineralized in this way into water, carbon dioxide or the like, and is discharged from the treatment tank 4 to the post-treatment tank 11. The illustrated post-treatment tank 11 includes a neutralization tank 12, a sedimentation tank 13, a coagulation sedimentation tank 14, a filtration tank 15, a pH adjustment tank 16, a treated water tank 17, and the like.
Since hydrogen peroxide is effectively used for generating OH radicals as described above, the residual amount after the treatment is very small, and the use of the neutralizing agent in the neutralization tank 12 is negligible or absent ( For example, the residual peroxide ion concentration is about 0 to 3% or less of the hydrogen peroxide used).
And the to-be-processed water 3 is adjusted to the state which can be drained by passing through the post-treatment tank 11, and is drained outside.

(11) In this treatment method, as described above, the ethylene glycols 1 contained in the water to be treated 3 are mineralized based on the treatment process of the Fenton method and the like, but this is easily and easily realized.
That is, the amount of chemicals added such as hydrogen peroxide, divalent iron ions, and Fenton's reagent such as a pH adjuster is easily calculated from the theoretical reaction value, and is about several times larger than the theoretical reaction value. However, it is actually added as a necessary amount, so that the addition amount is optimized.
The treatment apparatus 2 is provided with a raw water tank 9 and a post-treatment tank 11 with a treatment tank 4 as the center, and a hydrogen peroxide addition means 6, an iron ion addition means 7, a pH adjustment means 8 and the like. It consists of the structure which was made. That is, in this processing method, the processing device 2 having a relatively simple configuration is used, and stable processing is possible.
The operation of the present invention is as described above.

<Oxidation and decomposition processes of ethylene glycol>
Here, regarding the processing method of the present invention, the details of the oxidation and decomposition processes of ethylene glycol, which is an application example thereof, will be described.
That is, one example of the above-mentioned place entitled “Reaction (oxidation and decomposition of ethylene glycols 1) in the treatment tank 4” is theoretically verified.
Ethylene glycol (C ₂ H ₆ O ₂ ) contained in the water to be treated 3 follows the chain process of Chemical Formula 12 to Chemical Formula 14 described below, including the organic structure of an unstable intermediate of the decomposition process. As a result, they are sequentially oxidized with OH radicals (.OH), and thus decomposed and mineralized into water (H ₂ O) and carbon dioxide (C 0 ₂ ).

The reaction formulas of Chemical Formulas 12 to 14 are as follows. First, ethylene glycol, which is a starting material, is oxidized by the reaction formula of Chemical Formula 12 in which alcohol OH at both ends is deprived of hydrogen atoms by OH radicals, and the OH radicals are returned to water. At the same time, the oxygen atom is double-bonded with the carbon atom, thereby forming formaldehyde (H—CHO).
Then, the reaction formula proceeds to Chemical Formula 13, and formaldehyde is oxidized by depriving of hydrogen atoms by OH radicals, and the OH radicals are returned to water and the next OH radicals are attached to formic acid (H-COOH). It becomes. In the reaction formula of Chemical Formula 14, formic acid is oxidized and decomposed into carbon dioxide (CO ₂ ) and water (H ₂ O) by OH radicals.
In this way, ethylene glycol is theoretically oxidized, decomposed, and mineralized by following the chain process of the reaction formulas of Chemical Formula 12 to Chemical Formula 14.
By the way, when the place explained above is summarized (that is, when each reaction formula is added up), the following general reaction formula of Chemical Formula 15 is obtained.

In the general reaction formula of Chemical Formula 15, 1 mol of ethylene glycol is theoretically decomposed and mineralized by 10 mol of OH radicals into 8 mol of water and 2 mol of carbon dioxide.
In this example, 10 mol of OH radicals may be prepared in advance as a theoretical reaction value, but the actual required amount is prepared, for example, several times as many as that. Of course, the same applies to hydrogen peroxide, divalent iron ions, and the like, which are OH radical products.
Details of the oxidation and decomposition processes of ethylene glycol are as described above.

≪About oxidation and decomposition process of diethylene glycol≫
Next, regarding the treatment method of the present invention, details of oxidation and decomposition processes of diethylene glycol, which is an application example thereof, will be described.
That is, one example of the above-mentioned place entitled “Reaction (oxidation and decomposition of ethylene glycols 1) in the treatment tank 4” is theoretically verified.
Diethylene glycol (C ₄ H ₁₀ O ₃ ) contained in the water to be treated 3 is obtained by following the chain process of Chemical Formula 16 to Chemical Formula 19 described below, including the organic structure of an unstable intermediate of the decomposition process. Then, it is sequentially oxidized with OH radicals (.OH), so that it is decomposed and mineralized into water (H ₂ O), carbon dioxide (C 0 ₂ ) and oxygen (O ₂ ).

The reaction formulas of the chemical formulas 16 to 19 are as follows. First, diethylene glycol, which is a starting material, is oxidized by the reaction formula of Chemical Formula 16 in which alcohols OH at both ends are deprived of hydrogen atoms by OH radicals, and the OH radicals are returned to water. At the same time, the oxygen atom is double-bonded with the carbon atom, thereby forming formaldehyde (H—CHO).
Then, when the generation of the formaldehyde, the bonding electrons are to C-C single bond cleavage movement, by the following OH radicals _{attach, HO-CH 2 -O-CH} 2 -OH is generated. The generated HO—CH ₂ —O—CH ₂ —OH has the following reaction formula 17: Oxidation and decomposition by OH radicals cause the hydrogen atom of the OH group to return to water and formaldehyde Generated. At that time, oxygen (O ₂ ) is also generated derivatively.
Next, the process proceeds to the reaction formula of Chemical Formula 18, and formaldehyde generated by the chemical formulas of Chemical Formula 16 and Chemical Formula 17 is oxidized by depriving of hydrogen atoms by OH radicals, and the OH radicals are returned to water. By attaching the OH radical, formic acid (H-COOH) is obtained. In the reaction formula of chemical formula 19, formic acid is oxidized and decomposed into carbon dioxide (CO ₂ ) and water (H ₂ O) by OH radicals.
In this way, diethylene glycol is theoretically oxidized, decomposed, and mineralized by following the chain process of the reaction formulas of Chemical Formula 16 to Chemical Formula 19.
By the way, when the place explained above is summarized (that is, when each reaction formula is added up), the following general reaction formula of Chemical Formula 20 is obtained.

In the general reaction formula of Chemical Formula 20, 1 mol of diethylene glycol is theoretically mineralized to 16 mol of water, 4 mol of carbon dioxide and 1/2 mol of oxygen by 22 mol of OH radicals.
In this example, OH radicals may be prepared in advance in an amount of 22 mol as a theoretical reaction value, but the actual required amount is prepared several times, for example, several times as much. Of course, the same applies to hydrogen peroxide, divalent iron ions, and the like, which are OH radical products.
The details of the oxidation and decomposition processes of diethylene glycol are as described above.

Here, an example of the processing method of the present invention will be described.
In this example, after supplying 1 L of treated water 3 containing ethylene glycol as a sample A to a treatment tank 4 at a room temperature of 26 ° C., the amount of chemical addition is changed for each of the samples B, C, and D. Fenton treatment.
First, the test conditions are as follows <Sample B>
・ Sulfuric acid (H ₂ SO ₄ ) (60%): 0.090 mL / L
Hydrogen peroxide (H ₂ O ₂ ) (35%): 0.694 mL / L
Ferrous sulfate (FeSO ₄ · 7H ₂ O): 1.110 g / L
・ Caustic soda (NaOH) (25%): 1.035 mL / L
<Sample C>
・ Sulfuric acid (H ₂ SO ₄ ) (60%): 0.090 mL / L
Hydrogen peroxide (H ₂ O ₂ ) (35%): 1.388 mL / L
Ferrous sulfate (FeSO ₄ · 7H ₂ O): 2.220 g / L
・ Caustic soda (NaOH) (25%): 1.035 mL / L
<Sample D>
・ Sulfuric acid (H ₂ SO ₄ ) (60%): 0.090 mL / L
Hydrogen peroxide (H ₂ O ₂ ) (35%): 0.347 mL / L
Ferrous sulfate (FeSO ₄ · 7H ₂ O): 0.555 g / L
・ Caustic soda (NaOH) (25%): 1.035 mL / L
That is, with respect to hydrogen peroxide and ferrous sulfate, which are generation sources of OH radicals in the Fenton reaction, in Sample B, the addition amount is 1/2 of the theoretical value described above (for example, refer to the reaction formula of Chemical Formula 3). In sample C, it was added according to the theoretical value, and in sample D, it was added at 1/4 of the theoretical value. For sulfuric acid and caustic soda, the same amount was added to each sample.
Under such test conditions, regarding the content of ethylene glycol contained in the water to be treated 3 and other analysis items, the sample A before the Fenton treatment and the samples B, C, and D after the Fenton treatment As a result of the measurement, the following data in Table 1 was obtained.

From the results shown in Table 1, it was confirmed by data that ethylene glycol was oxidized, decomposed, and mineralized into water and carbon dioxide, and hardly existed in the water to be treated 3.
In addition, according to the data of COD-Cr analysis (CHEMICAL OXYGEN DEMAND chemical oxygen demand test using potassium dichromate), TOC analysis (TOTAL ORGANIC CARBON total organic carbon content test), electric conductivity data, etc. The mineralization of ethylene glycol was supported. The electrical conductivity increases in proportion to the amount of Fenton reagent and pH adjuster added.
About an Example, it is as above.

The ethylene glycol treatment method according to the present invention is a configuration flow diagram for explaining the best mode for carrying out the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ethylene glycol 2 Treatment apparatus 3 Water to be treated 4 Treatment tank 5 Treatment water supply means 6 Hydrogen peroxide addition means 7 Iron ion addition means 8 pH adjustment means 9 Raw water tank 10 pH adjustment tank 11 Post-treatment tank 12 Neutralization tank 13 Precipitation tank 14 Coagulation sedimentation tank 15 Filtration tank 16 pH adjustment tank 17 Treated water tank

Claims (1)

A treatment method that oxidizes and decomposes ethylene glycol contained in water to be treated based on the Fenton process. Hydrogen peroxide and divalent iron ions are treated against water to be treated containing ethylene glycol. A solution and a pH adjuster are added,
Hydrogen peroxide is added in the treatment tank at the beginning of the reaction,
In the treatment tank, the divalent iron ion solution is intermittently added repeatedly by repeating a plurality of cycles after the addition of hydrogen peroxide, so that the OH radicals generated below return to water and are wasted. Function to avoid
As for the pH adjuster, an acid pH adjuster is first added to the water to be treated supplied to the treatment tank in the pH adjustment tank, and divalent iron is added in the treatment tank after the addition of hydrogen peroxide. An alkaline pH adjuster is added each time the ionic solution is added in a divided manner, so that the water to be treated is maintained at a weak acidity of pH 3 to pH 5, and the reaction in which hydrogen peroxide is decomposed and wasted into water and oxygen is suppressed. Function as
The amount of hydrogen peroxide and divalent iron ions added is calculated based on the theoretical reaction value based on the reaction formula.
First, from the specific content of ethylene glycol contained in the water to be treated, the number of moles of the theoretical reaction value of OH radical is obtained as a reference, and then the actual required number of moles of OH radical is obtained based on this standard. From the required number of moles of OH radicals, the theoretical number of moles of reaction of hydrogen peroxide and divalent iron ions, which are OH radical products, is obtained as a reference, and The actual required number of moles of hydrogen peroxide and divalent iron ions to be prepared is calculated more than this standard,
The addition timing of hydrogen peroxide and divalent iron ions is when hydrogen peroxide is used up and hydrogen peroxide is exhausted from the water to be treated in the treatment tank. When the previously added portion is used up, the divalent iron ions disappear from the water to be treated in the treatment tank.
As for the OH radical production reaction, hydrogen peroxide is reduced with divalent iron ions each time it is added in a divided manner, and in addition to the Fenton main reaction, in which OH radicals are produced, the hydrogen peroxide is further reduced. The generated hydroxide ions are oxidized by trivalent iron ions generated by the oxidation reaction of divalent iron ions to generate OH radicals, and the generated OH radicals are further covered. The reaction of reacting with the water of the treated water to generate new OH radicals and water is repeated in a chain, and the trivalent iron ions generated by the oxidation reaction of the divalent iron ions The reaction of reacting with hydrogen oxide to at least generate new OH radicals is repeated in a chain, and generation of OH radicals is terminated when hydrogen peroxide is exhausted in the treatment tank,
Therefore, ethylene glycol or diethylene glycol contained in the water to be treated is oxidized and decomposed by the OH radicals thus generated, ethylene glycol becomes water and carbon dioxide, diethylene glycol becomes water, carbon dioxide and oxygen, A method for treating ethylene glycol, characterized in that each is mineralized.

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