JPH06206065A - Removal of halogenated hydrocarbon - Google Patents

Abstract

PURPOSE:To enhance the removal ratio of trihalomethane and to decompose trihalomethane by active oxygen generated from an, anode at the time of the electrolysis of water to prevent the re-dissolution thereof by applying positive charge to activated carbon and adsorption removing halogenated hydrocarbon. CONSTITUTION:In the removal of halogenated hydrocarbon, at first, a usual activated carbon water purifier 1, an anode 5 and a cathode 6 are inserted and the cathode 6 is covered with a cloth diaphragm 7 to be insulated. Activated carbon 4 is well received in the water purifier 1 so that the particles thereof come into contact with the anode 5 directly and indirectly. In this case, since the cathode 6 is insulated, the activated carbon in the water purifier 1 entirely becomes a form charged with positive electricity. When water is injected from a water inlet 2, water is distributed by a fluffy polymer 8 to pass the activated carbon bed of positive potential and trihalomethane or bacteria of negative potential is adsorbed. In this case, since cathode water is also mixed to be issued, pH or redox potential does not change as the whole of water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing halogenated hydrocarbons (trihalomethanes) in water, especially tap water.

[0002]

2. Description of the Related Art Although tap water is purified with activated carbon, hollow fiber membranes, ceramic filters, etc., it mainly removes free chlorine, but there has been no method for completely removing halogenated hydrocarbons (trihalomethane). In addition, halogenated hydrocarbons are mixed in the semiconductor wastewater, but there is no suitable removal method.

[0003]

DISCLOSURE OF THE INVENTION According to the present invention, a halogenated hydrocarbon (trihalomethane), which has hitherto been considered to be difficult to completely remove, is given a positive charge to the activated carbon to adsorb a halogenated hydrocarbon which is easily negatively charged to the activated carbon. It provides a safe water by increasing the removal rate in a form that is easy to handle.

[0004]

[Means for Solving the Problems] Activated carbon partially adsorbs halogenated hydrocarbons (generic name: trihalomethane), but this is not sufficient and the adsorption rate remains at about 60 to 80%. The present invention uses an electrochemical method to increase this adsorption rate to 95-100.
It is a method of approaching to%. It is known that halogenated hydrocarbons (hereinafter referred to as trihalomethanes) generally have a negative potential. Therefore, when a positive potential is applied to activated carbon, the halogenated hydrocarbon is adsorbed on the activated carbon. This method is the same when the anode is made a porous electrode and water is passed through it. However, it is necessary that the carbon layer in the electrode has fine holes to form an activated carbon layer. In the case of electrolysis of pure water, OH ⁻ is discharged at the anode, a reaction of 2OH → H ₂ O + O occurs, and active oxygen is generated. At this time, the adsorbed trihalomethane is oxidatively decomposed by the generated active oxygen, so there is no danger of redissolving, but the adsorption rate is poor with ordinary activated carbon only, and the adsorbed trihalomethane remains adsorbed, so the temperature of the water may change. There is a risk of redissolving.

Bacteria, when present in water, have a negative potential due to the zeta potential. Therefore, bacteria are also easily adsorbed on activated carbon having a positive potential. Besides, OH
^-Is also discharged to become OH and active oxygen is generated, so bacteria are also sterilized. On the other hand, H ⁺ ions are discharged at the cathode,
It becomes an atom and the liquid becomes reducible. If water with trihalomethane and sterilization removed through the anode is discharged through the cathode, P
It should be similar to H, ORP raw water, and should have trihalomethane removed, small clusters and good body water.

[0006]

The method of the present invention will be described in detail with reference to the drawings. First, an anode 5 and a cathode 6 are inserted into an ordinary activated carbon water purifier as shown in FIG. The anode is covered with a cloth diaphragm 7 for insulation. Activated carbon 4
Is filled well so that the particles of each activated carbon come into direct and indirect contact with the anode. In this case, since the cathode 6 is insulated by the cloth diaphragm 7, the activated carbon in the water purifier is all positively charged. When water is injected from the water inlet 2 in this way, it is distributed by the cotton-like polymer 8 and adsorbs trihalomethane or sterilizer having a negative potential while passing through the activated carbon layer having a positive potential. The purified water passes through the cotton-like polymer 8 and the water outlet 3
Get out more. In this case, the cathode water also comes out as a mixture,
The pH and redox potential of the water as a whole do not change. However, compared to ordinary activated carbon, the electric attraction force is added and the trihalomethane removal rate is improved.
Na

FIG. 2 shows a modification of the method of FIG. 1, in which the electrolytic cell is divided into an anode cell 11 and a cathode cell 12. There is a diaphragm 13 between them, which allows ions to pass but hardly water. Water enters through the inlet 9 and the anode 14 and conductive fibers (activated carbon fibers, etc.) 1
Granular activated carbon that is electrically connected at 8 and has a positive potential 1
Adsorbed on 7. At this time, conductive fibers (such as activated carbon fibers)
Is used to improve the contact between the anode and the granular activated carbon. Trihalomethane with a negative potential is easily adsorbed on activated carbon with a positive potential, but bacteria contained in water are also negatively charged due to the zeta potential, and they are also adsorbed on activated carbon. Moreover, water is ionized into a small amount of H ⁺ and OH ⁻ , and the negative ion OH ⁻ is discharged on the surface of the activated carbon having a positive potential to generate active oxygen. This active oxygen has a very strong oxidizing power and oxidizes and decomposes bacteria and trihalomethane adsorbed on the activated carbon.

The water exiting the anode tank essentially has the property of acidic ionized water, but the active oxygen produced is oxidative decomposition of trihalomethanes, oxidative decomposition of bacteria, and the production of CO ₂ by reaction with activated carbon. Is used, and as time passes, oxygen molecules are generated by the binding of active oxygens, so
The amount of active oxygen decreases, and the properties of acidic ionized water become considerably weaker. When calcium lactate or the like is added to this water and sent to the cathode tank, calcium ion water is generated in the cathode tank and active oxygen is completely disappeared, and water having characteristics as alkaline ion water is obtained. In the device of FIG. 1 in which the anode and the cathode coexist in the same electrolytic cell, the PH and O of the water obtained
The RP is essentially unchanged, but in the device of FIG. 2, the anode tank and the cathode tank are separated by a diaphragm, and when the reaction in the anode tank is completed, the property as acidic ionized water is considerably lost. Is treated in a cathode tank, the treated water has the property of alkaline ionized water.

The method of the present invention is a method in which a positive potential is applied to activated carbon and trihalomethane having a negative potential is electro-adsorbed on the activated carbon. Further, it also has an action of oxidatively decomposing the trihalomethane adsorbed by the anodic reaction of water electrolysis to prevent redissolution of trihalomethane, which is a problem in adsorbing activated carbon. This method also has an effect of adsorbing free chlorine as an ordinary activated carbon and reducing water clusters by an ordinary electrolysis. Trihalomethane is a general term for organic chlorine and bromine compounds such as chloroform, bromodichloromethane, dibromochloromethane, and bromoform, and each has a form in which three hydrogen atoms in the methane molecule are replaced with chlorine or bromine. Chlorine and bromine have seven outermost electrons, and they tend to capture one electron and bring it closer to eight stabilizing electrons. Therefore, in terms of potential, it will have a negative potential,
As it is attracted to the activated carbon with a positive potential, the trihalomethane adsorption capacity increases. In this case, activated carbon can be added to and adsorbed in the cathode tank, but rather, it is better to add a conductive substance such as carbon fiber having no adsorption ability in order to simply increase the electrode area in order to produce alkaline ionized water. In addition, the volume can be made smaller than that of the anode tank to improve efficiency. In actual use, when flowing water, the electrolysis voltage is raised to 3 to 12 V to cause the reaction to proceed quickly, but when water is stopped, it is reduced to 1 to 3 V to stop the generation of germs and restart. It is a time advantage.

[0010]

【Example】

(Example 1) Using the apparatus shown in FIG. 1, 194 g of activated carbon was added, and 60 l of water containing 10 ppm of chloroform was flown at a voltage of 9 V and a flow rate of 2 l / min. The water temperature was 6.5 ° C. For comparison, the same device was used for adsorption under the same conditions without applying voltage. The results are shown below. The analysis method was 366 μm using pyridine-caustic soda.
Colorimetric method.

(Example 2) Using the apparatus shown in FIG. 2, 346 g of granular activated carbon was added, and a test of voltage 9V, 6V, 0V was conducted. The results are shown below.

(Example 3) 0.2 pp of treated water of Example 2
m was further introduced into the apparatus of FIG. 2 and the second treatment was performed. The analytical method was a colorimetric method using pyridine-caustic soda, but it was below the detection limit (0.05 ppm).

[0013]

EFFECTS OF THE INVENTION There has been no suitable method for removing trihalomethanes, and it was about 60 to 80% by activated carbon adsorption. According to the method of the present invention, a positive potential is applied to activated carbon to adsorb trihalomethane or the like, which tends to be negatively charged. This is a method in which electric adsorption is added to the adsorption capacity of conventional activated carbon, and trihalomethane is decomposed by active oxygen generated at the anode during water electrolysis to prevent redissolution.
This method has an advantage that bacteria other than trihalomethane are sterilized, and can be used as alkaline ionized water by passing it through a cathode.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a water purifier A according to the present invention.

FIG. 2 is an explanatory diagram of a water purifier B according to the present invention.

[Explanation of symbols]

1. Water purifier 2. Water inlet
3. Water outlet 4. Activated carbon 5. anode
6. Cathode 7. Fabric diaphragm 8. Cotton-like polymer
9. Water inlet 10. Water outlet 11. Anode tank 1
2. Cathode tank 13. Diaphragm 14. Anode 1
5. Cathode 16. Three-way cock 17. Granular activated carbon 1
8. Activated carbon fiber 19. Conductive fiber

Claims (3)

[Claims] 1. A method for removing a halogenated hydrocarbon, which comprises applying a positive charge to activated carbon to adsorb and remove the halogenated hydrocarbon. 2. The method for removing halogenated hydrocarbon according to claim 1, wherein activated carbon is added to the water electrolysis tank, and the positive electrode and activated carbon are brought into conduction with each other by contacting activated carbons or by carbon fibers. 3. A method of adding granular activated carbon to an anode cell for water electrolysis, supplying a positive potential to the activated carbon with carbon fiber or activated carbon fiber or conductive fiber to pass water, and then passing water to the cathode cell. Item 2. A method for removing a halogenated hydrocarbon according to Item 1.