JP4596937B2 - Water purification method using sodium hypochlorite - Google Patents

Description

  The present invention, for example, sterilizes miscellaneous bacteria contained in water such as seawater, river water, well water or tap water with sodium hypochlorite, and then purifies the water by reducing the sterilized water, The present invention relates to a method for purifying water using sodium hypochlorite that can be used as water used for aquaculture.

  Conventionally, as a method of electrolyzing water using alternating current, for example, a pair of electrodes made of a metal that lowers the oxidation-reduction potential in a liquid and at least one first grounding electrode are disposed, An alternating current is applied between the pair of electrodes, the frequency of the alternating current is controlled, and the first grounding electrode is periodically controlled from the ground potential to a positive potential to lower the redox potential of the liquid, There is a liquid AC electrolysis method in which a mesh-like second grounding electrode having a substantially box shape is disposed around the pair of electrodes and the first grounding electrode (see Patent Document 1).

  Further, as a method of electrolyzing water using alternating current and purifying water using sodium hypochlorite, for example, a step of preparing a culture tank for culturing seafood in seawater; Connecting an AC electrolytic treatment apparatus comprising an electrolytic chamber, an AC electrode disposed in the electrolytic chamber, and a mixture of a minute divided electrode body and a minute insulator filled between the AC electrodes to the line and the outlet line; Generating sodium hypochlorite by generating sodium hydroxide and chlorine in the gap of the mixture; sterilizing while contacting the sodium hypochlorite and the pathogenic virus in the gap of the mixture; In a gap between the mixture, the sodium hypochlorite and ammonium in the seawater are stirred and reacted to convert to sodium chloride, water and nitrogen. Pneumoniae comprising the steps of detoxifying; a step of circulating the detoxified seawater farming aquariums; consisting, there is a method of cultivating shellfish (see Patent Document 2).

JP 2003-236543 A JP 2003-52275 A

  However, in the known technique of Patent Document 2, an electrochemical treatment is performed in which sodium hydroxide and chlorine are generated by treatment by alternating current electrolysis to produce sodium hypochlorite. In the step of reducing sodium oxide, the chemical reaction of converting sodium hypochlorite and ammonium into sodium chloride, water, and nitrogen by stirring reaction is performed, and thus the reaction takes a long time. It has the problem that it requires.

  Therefore, there is a problem to be solved by reducing sodium hypochlorite by electrochemical treatment.

  The water purification method using sodium hypochlorite according to the present invention as a specific means for solving the problems of the conventional example described above includes a pair of alternating current electrodes in water containing sodium chloride, and a smaller area than the alternating current electrodes. A first ground electrode having the same area and a second ground electrode having a larger area than the total area of the pair of AC electrodes and capable of switching between a ground state and a non-ground state. The ground electrode is brought into an ungrounded state, and an alternating current is applied between the pair of alternating current electrodes and electrolyzed to generate sodium hypochlorite salt to sterilize the water. The most important feature is that the sodium hypochlorite salt is reduced to sodium chloride to purify the water by applying an alternating current between the pair of alternating current electrodes and performing electrolysis while switching to the grounded state.

  In the present invention, the pair of AC electrodes is formed using titanium, platinum, or a stable metal having no solubility made of platinum plated with platinum, and the first ground electrode and the second ground electrode are: Formed using a highly soluble metal made of magnesium, aluminum, iron, copper, zinc, brass, and stainless steel; the second ground electrode is formed in a cylindrical shape or a meshed cylindrical shape, and a pair of AC electrodes The sodium chloride contained in the water has a concentration of about 0.01% or more as an additional requirement.

  The method for purifying water using sodium hypochlorite according to the present invention includes a pair of alternating current electrodes in water containing sodium chloride, a first ground electrode having a smaller area to the same area than the alternating current electrodes, and the pair A second ground electrode having a larger area than the total area of the AC electrodes and capable of switching between a grounded state and a non-grounded state, placing the second grounded electrode in a non-grounded state, and After alternating current is applied between the AC electrodes and electrolyzed to generate sodium hypochlorite to sterilize the water, the second ground electrode is switched to the ground state, and between the pair of AC electrodes. Since the water is purified by reducing the sodium hypochlorite salt to sodium chloride by applying alternating current and electrolysis, electrochemical treatment is also performed in the step of reducing sodium hypochlorite. It can be simply an excellent effect that sodium hypochlorite more smoothly than to chemically react can be reduced.

Next, the present invention will be described in detail based on specific embodiments.
A water purification method using sodium hypochlorite according to an embodiment of the present invention will be described with reference to FIGS. The water purification method using sodium hypochlorite according to the present invention is based on the invention described in Japanese Patent Application Laid-Open Nos. 2003-236543 and 2004-263272 by the same applicant. However, in the present invention, sodium hypochlorite salt is generated to sterilize water, and the sodium hypochlorite salt is electrochemically reduced to purify water.

  In FIG. 1, a pair of AC electrodes 2a and 2b, a first ground electrode 3 and a second ground electrode 4 are disposed in water (for example, seawater) containing sodium chloride in an aquarium 1, and AC electrolysis is performed. An example of a circuit diagram that can perform the above is shown. The water containing sodium chloride preferably has a concentration of about 0.01% or more. When sodium chloride is not contained in the water, the concentration is about 0.01% or more. Sodium chloride (salt) may be added to the water, and the circuit diagram of FIG. 1 is an example. For example, Japanese Patent Application Laid-Open No. 2004-344746 by the same applicant may be used as long as it is a circuit capable of AC electrolysis of water. Any circuit such as the circuit shown in FIG. 4 may be used.

  The pair of AC electrodes 2a and 2b is preferably formed using, for example, a stable metal having no solubility such as titanium, platinum, or titanium plated with platinum. The second ground electrode 4 is preferably formed using a highly soluble metal such as magnesium, aluminum, iron, copper, zinc, brass, and stainless steel.

The first ground electrode 3 uses an electrode having a smaller area or the same area than each of the AC electrodes 2a and 2b, that is, an area (surface area) represented by Formula 1, and the second ground electrode 3 The ground electrode 4 uses an electrode (surface area) having an area larger than the total area of the pair of AC electrodes 2a and 2b, that is, an area represented by Formula 2, and further, the second ground electrode 4 Is preferably formed in a cylindrical shape or a mesh-like cylindrical shape, and is disposed so as to cover the periphery of the pair of AC electrodes 2a, 2b and the first ground electrode 3 as shown in FIG. It is.
(Formula 1)
Area of AC electrode 2a = area of AC electrode 2b ≧ area of first ground electrode 3 (Formula 2)
Total area of a pair of AC electrodes 2a, 2b <area of second ground electrode 4

  The reason why the areas of the first ground electrode 3 and the second ground electrode 4 are as shown in the formulas 1 and 2 is that the first ground electrode 3 and the second ground electrode 4 This is because, depending on the area, sodium hypochlorite is generated or sodium hypochlorite is reduced, but the detailed mechanism of the reaction of sodium hypochlorite reduction is not elucidated. Since atomic hydrogen (active hydrogen) generated from the first ground electrode 3 and the second ground electrode 4 reacts with oxygen of sodium hypochlorite, sodium hypochlorite is reduced. Therefore, at that time, it is assumed that the atomic hydrogen (active hydrogen) is increased by widening the areas of the first ground electrode 3 and the second ground electrode 4.

  A high frequency switch for converting a direct current from the direct current power source 5 into a high frequency alternating current and applying it to the pair of alternating current electrodes 2a and 2b via a variable resistor 6 between the pair of alternating current electrodes 2a and 2b and the direct current power source 5. 7a and 7b are connected. These high-frequency switches 7a and 7b are composed of transistors 8a and 9a and 8b and 9b, respectively. The pair of alternating current electrodes 2a and 2b are connected via a capacitor 10, and an alternating current is applied between the pair of alternating current electrodes 2a and 2b. The DC power source 5 can be used while being selectively adjusted in the range of 10 to 50 V depending on the use of the treated water.

  The high frequency switch 7a, 7b is connected to a high frequency switching command circuit 12 comprising a flip-flop circuit for giving a high frequency switching command to the high frequency switches 7a, 7b via resistors 11a, 11b, respectively. A high frequency oscillation circuit 13 composed of a voltage controlled oscillator (VCO) whose oscillation frequency changes in response to a control signal is connected. A control circuit 14 incorporating a random voltage generator is connected to the high-frequency oscillation circuit 13.

  The high frequency oscillation circuit 13 is a variable frequency type oscillation circuit, and the oscillation frequency can be controlled by a voltage value of a control signal supplied to a voltage controlled oscillator (VCO). The frequency fluctuation range at this time is, for example, about 3 to 5 KHz above and below the center frequency (about 30 KHz).

  The control circuit 14 supplies a control voltage for controlling the oscillation frequency to the high-frequency oscillation circuit 13. The control circuit 14 includes a random signal generator, and outputs a control signal whose voltage value changes in accordance with the random signal generated by the random signal generator. The shift register 15 (SFR) has a 16-stage configuration, and the stored information can be read in parallel from the terminals Q0 to Q15. The shift operation of the shift register 15 (SFR) is controlled by a shift pulse supplied from the pulse generator 16 (PG) to the terminal CK of the shift register 15 (SFR). Further, the flip-flop 17 performs an inversion operation by the pulse of the pulse generator 16, and abrupt frequency fluctuation is performed each time the inversion is performed.

  The gate (GT) outputs a signal “1” if the signals input to both input terminals are the same, and outputs a signal “0” if they are different. This is a gate that performs a so-called exclusive OR operation, and acts as a coincidence detection circuit. One of the input terminals of the gate (GT) has a signal output from the even stage of the shift register 15 (SFR), for example, the terminal Q6 of the sixth stage, and the other has an odd stage, for example, the ninth stage. The signals output from the terminal Q9 are respectively input. The result of coincidence detection by the gate (GT) is input to the lowest 0th stage from the terminal D of the shift register 15 (SFR). By sequentially shifting this information upward, random number information is stored in the shift register 15 (SFR).

  The random number information stored in the shift register 15 (SFR) is taken out by a resistor r from about half of the appropriately selected stages. In this embodiment, signals are extracted from the first, third, eighth, tenth, and twelfth to fifteenth stages. The resistor r connects the terminals Q1, Q3, Q8, Q10, and Q12 to Q15 of these stages to a common connection point A. This connection point A is connected to a voltage controlled oscillator (VCO) constituting the high frequency oscillation circuit 13. On the other hand, the voltage controlled oscillator (VCO) is also connected to a flip-flop circuit 17 connected to the pulse generator 16.

  Therefore, when the pattern of the random number information stored in each of these stages changes, the combined value of the resistor r connected to the high level and the low level changes, so that the voltage at the connection point A fluctuates accordingly. Thus, a random signal is created. This operation may be reproduced using a computer or the like.

  The pulse generator 16 is configured to send a continuous pulse having a center frequency of 5 Hz, for example, and to change the pulse repetition period according to the voltage value of the signal input to the voltage controlled oscillator (VCO). This frequency fluctuation range is about several hertz above and below the center frequency. The voltage at the connection point A is applied to the terminal of the pulse generator 16 via the resistor r2. Therefore, in the pulse generator 16, the repetition period of the pulse varies according to the random signal from the shift register 15 (SFR). The shift register 15 (SFR) uses the output of the pulse generator 16 as a shift pulse. Therefore, the control signal output to the voltage controlled oscillator (VCO) changes its voltage value and fluctuation period at random, and the flip-flop circuit 17 creates a sudden change portion.

  Here, in this control circuit 14, the control signal is created using a pattern of random number information accumulated in about half of the stages of the shift register 15 (SFR), and the adopted stage is also biased, Further, as described above, as the input information of the shift register 15 (SFR), the coincidence detection result of information selected one by one from each of even and odd numbers is used. Frequently changing parts appear frequently, and the same change pattern is not repeated in a short period of time.

  When the switch of the DC power supply 5 of the AC electrolysis apparatus configured as described above is turned on, the control circuit 14 operates as described above, and a control signal corresponding to the random signal is sent to the high-frequency oscillation circuit 13, The oscillation frequency is controlled and changes randomly. A high-frequency signal that randomly changes is supplied from the high-frequency oscillation circuit 13 to the high-frequency switching command circuit 12. When a random high-frequency signal is given to the high-frequency switching command circuit 12, a high-frequency switching command is issued from the high-frequency switching command circuit 12, and is given alternately to the high-frequency switches 7a and 7b, and these high-frequency switches 7a and 7b have a high cycle. A high-frequency alternating current that is randomly turned on and off is formed and applied alternately to the pair of alternating current electrodes 2 a and 2 b disposed in the liquid in the water tank 1.

  Here, the oscillation frequency sent from the high-frequency oscillation circuit 13 changes its voltage value and the duration of the voltage value completely at random, and frequently has a very fluctuating portion where the voltage value rapidly rises and then drops rapidly. Contains.

  As described in Japanese Patent Application Laid-Open No. 11-300358, when the transmission frequency is changed in this manner, white deposits on the electrode surface are significantly less than when the transmission frequency is not changed. It was confirmed by.

  In short, since there are few white deposits on the electrode surface, it is possible to prevent the effect of lowering the redox potential of water from being lowered even when used for a long time. Therefore, it is better to change the transmission frequency in the same manner as in JP-A-11-300388.

  The first ground electrode 3 may be in a grounded state, but may be connected to the timer circuit 18 using a pulse signal as shown in FIG. 1, for example. The timer circuit 18 is connected to the grounded electrode of the DC power supply 5 and one of the pair of AC electrodes 2a and 2b, and is connected to the grounded electrode by the pulse signal of the timer circuit 18 and AC. The electrode is switched, and the first ground electrode 3 is periodically applied with an alternating current from the ground potential. Thus, by temporarily applying an alternating current to the potential of the first ground electrode 3, the scale adsorbed on the first ground electrode 3 can be removed and cleaned.

  Thus, the time for applying alternating current to the first ground electrode 3 may be shorter than the time for grounding, and the time for applying alternating current is about 1/10 to the time for grounding. For example, when the grounding state is about 20 minutes, it takes about 10 seconds to make the potential positive when the grounding state is about 20 minutes. By cleaning the first ground electrode 3 in this way, adhesion of scales and the like can be further prevented, and the efficiency of AC electrolysis can be maintained higher.

  The second ground electrode 4 is connected to one end of the switching means 19, and the other end of the switching means 19 is grounded. Therefore, by switching the state of the switching means 19, the second ground electrode 4 can be selectively switched between the ground state and the non-ground state.

  These circuits are housed in the circuit housing portion 20 shown in FIG. 2, and the pair of AC electrodes 2 a and 2 b, the first ground electrode 3, and the second ground electrode 4 are connected to the outside of the circuit housing portion 20. It is good also as an apparatus provided in.

  The operation of the water purification method using sodium hypochlorite according to the present invention in the circuit thus connected will be described. With the pair of AC electrodes 2a and 2b, the first ground electrode 3 and the second ground electrode 4 disposed in the water containing sodium chloride in the water tank 1, the switching means 19 is switched to switch to the second ground. The electrode 4 is not grounded, and electrolysis is performed by applying an alternating current between the pair of alternating current electrodes 2a and 2b.

When electrolysis is performed with alternating current when the second ground electrode 4 is in a non-grounded state in this way, on the instantaneous anode side of alternating current,
(Formula 3)
2NaCl → Cl ₂ + 2Na ⁺ + 2e
(Formula 4)
Cl ₂ + H ₂ O + 2Na ⁺ → NaClO + NaCl + 2H ⁺
(Formula 5)
2H ₂ O → O ₂ + 4H ⁺ + 4e
(Formula 6)
NaCl + H ₂ O → NaClO + 2H ⁺ + 2e
On the other hand, on the cathode side where the alternating current is instantaneous,
(Formula 7)
2H ⁺ + 2e → H ₂
(Formula 8)
Cl ₂ + 2Na ⁺ + 2e → 2NaCl
(Formula 9)
NaClO + 2H ⁺ + 2e → NaCl + H ₂ O
Reaction occurs.

  The water in the water tank 1 can be sterilized by NaClO (sodium hypochlorite) generated in the formula 4. The sterilization with sodium hypochlorite sodium salt may be as little as a few minutes.

  Next, the switching means 19 is switched to place the second ground electrode 4 in a grounded state, and an alternating current is applied between the pair of AC electrodes 2a and 2b to perform electrolysis.

When electrolysis is performed with alternating current when the second ground electrode 4 is in the ground state in this way, on the instantaneous cathode side of alternating current,
(Formula 10)
NaClO + 2H ⁺ + 2e → NaCl + H ₂ O
(Formula 11)
2H ₂ O + 2 e → H ₂ + 2OH ⁻
Is generated outside the second ground electrode 4 (Equation 12).
2NaCl → Cl ₂ + 2Na ⁺ + 2e
(Formula 13)
Cl ₂ + H ₂ O + 2Na ⁺ → NaClO + NaCl + 2H ⁺
(Formula 14)
2H ₂ O → O ₂ + 4H ⁺ + 4e
(Formula 15)
NaCl + H ₂ O → NaClO + 2H ⁺ + 2e
Therefore, sodium hypochlorite is efficiently reduced to sodium chloride and the water is purified.

  In this way, not only the process of generating sodium hypochlorite but also the process of reducing sodium hypochlorite can be electrochemically treated, so that it is simply chemically reacted. Therefore, sodium hypochlorite can be reduced more smoothly than before, and water can be easily and quickly sterilized and purified.

It is an example of the circuit diagram used when operating the purification | cleaning method of the water using the sodium hypochlorite which concerns on embodiment of this invention. It is the perspective view which expanded and showed schematically the apparatus provided with a pair of alternating current electrode used for the circuit, the 1st ground electrode, the 2nd ground electrode 4, etc. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water tank 2a, 2b A pair of alternating current electrode 3 1st ground electrode 4 2nd ground electrode 5 DC power supply 6 Variable resistance 7a, 7b High frequency switch 8a, 8b, 9a, 9b Transistor 10 Capacitor 11a, 11b Resistance 12 High frequency switching command Circuit 13 High-frequency oscillation circuit 14 Control circuit 15 Shift register 16 Pulse generator 17 Flip-flop 18 Timer circuit 19 Switching means 20 Circuit housing part

Claims (4)

Switching between a pair of AC electrodes in water containing sodium chloride, a first ground electrode having a smaller area or the same area than the AC electrode, and a larger area than the total area of the pair of AC electrodes and a ground state and a non-ground state A second ground electrode capable of being disposed;
The second ground electrode is brought into a non-ground state, and an alternating current is applied between the pair of alternating current electrodes and electrolyzed to generate sodium hypochlorite and sterilize the water,
The second ground electrode is switched to a ground state, and the water is purified by reducing the sodium hypochlorite salt to sodium chloride by applying an alternating current between the pair of alternating current electrodes and performing electrolysis. A water purification method using sodium hypochlorite as a feature. The pair of alternating current electrodes are formed using a stable non-soluble metal made of titanium, platinum, or titanium plated with platinum,
The first ground electrode and the second ground electrode are formed using a highly soluble metal made of magnesium, aluminum, iron, copper, zinc, brass, and stainless steel. Water purification method using sodium hypochlorite sodium salt. The second ground electrode is
Formed into a cylindrical shape or a cylindrical shape of mesh,
The water purification method using sodium hypochlorite according to claim 1 or 2, wherein the water is disposed so as to cover the periphery of the pair of AC electrodes and the first ground electrode. Sodium chloride contained in the water is
The method for purifying water using sodium hypochlorite according to claim 1, wherein the concentration is about 0.01% or more.

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