JP4602198B2 - Preparation method of chlorine dioxide water - Google Patents

Description

  The present invention relates to a method for preparing chlorine dioxide water useful for sterilization and sterilization of circulating water systems such as circulating baths and cooling water systems, sterilization cleaning of containers and production / filling lines in food and beverage factories, and sterilization cleaning of tableware. About.

  In recent years, a method using chlorine dioxide as a water-based disinfectant / disinfectant is becoming widespread. This chlorine dioxide has a stronger bactericidal action than chlorine and is also excellent in bactericidal properties for biofilms (biological membranes). In a circulating water system, the entire system can be sterilized and washed without causing clogging of the filter. There is an advantage. Therefore, as means for producing this chlorine dioxide, the following methods (1) to (4) using a chlorite such as sodium chlorite as a main raw material are conventionally known.

(1) Method of directly reacting chlorite and acid 5NaClO ₂ + 4HCl → 4ClO ₂ + 5NaCl + 2H ₂ O
(2) Method of allowing sodium hypochlorite and acid to act on chlorite 2NaClO ₂ + NaClO + 2HCl → 2ClO ₂ + 3NaCl + H ₂ O
(3) Method of causing chlorine gas to act on chlorite 2NaClO ₂ + Cl ₂ → 2ClO ₂ + 2NaCl
(4) Method of electrolyzing aqueous chlorite solution NaClO ₂ + H ₂ O → ClO ₂ + NaOH + 1 / 2H ₂

  In the above methods (1) and (2), phosphoric acid, citric acid and the like can be used in addition to hydrochloric acid exemplified as the acid. However, a higher chlorine dioxide generation rate is obtained with a shorter reaction time as the pH is lower. Therefore, high-concentration chlorine dioxide water prepared by these methods shows strong acidity, and thus requires careful handling and lowers the pH of the aqueous system when added to the aqueous system to be disinfected. Therefore, depending on the type of water system, there is a problem and there is a concern that the wetted part made of metal may be affected. In addition, since the method (2) mixes three kinds of liquids of chlorite, sodium hypochlorite and acid, there is also a problem that it is complicated in operation and inferior in workability.

  On the other hand, the method (3) using chlorine gas needs to ensure sufficient safety in handling toxic chlorine gas, and is difficult to adopt from the viewpoint of workability and equipment cost. Further, the method (4) by electrolysis has a problem in terms of cost because it requires special equipment.

  In view of the above-mentioned circumstances, the present invention is a method capable of preparing a neutral chlorine dioxide water having a high concentration and easy handling at a low cost and relatively safe, and further, an effective concentration and generation of the chlorine dioxide water. The object is to provide a preparation method in which the amount can be easily controlled.

In order to achieve the above object, a method for preparing chlorine dioxide water according to claim 1 of the present invention introduces an aqueous chlorite solution into a reaction vessel charged with a molded product of trichloroisocyanuric acid as a solid chlorinating agent. reacted Te, chlorine dioxide water produced is characterized in Rukoto is derived from the reaction vessel.

The invention of claim 2 is the process for the preparation of chlorine dioxide water of the claim 1, by adjusting the introduction rate and the concentration of the chlorite solution, it is assumed to control the effective concentration or amount of production of chlorine dioxide generating .

The invention of claim 3 is characterized in that, in the method for preparing chlorine dioxide water of claim 2 , the aqueous chlorite solution is introduced into the reaction vessel with a residence time of 0.5 hours or more.

According to the invention of claim 1, high concentration chlorine dioxide water can be stably and continuously prepared with only two kinds of molded products of trichlorisocyanuric acid which is a chlorite aqueous solution and a solid chlorinated agent. In addition, since solid chlorinated chemicals are generally less dangerous and easy to handle than liquid sodium chlorite and hydrochloric acid, preparation can be performed with good workability and safety. Moreover, since the pH of the prepared chlorine dioxide water is in a substantially neutral range, even if it is added to the water system to be sterilized and sterilized as much as necessary, the pH of the water system is not lowered, and the metal wetted part is There is no fear of invading. In addition, a preparation device can be constructed very simply with a reaction vessel, a chlorite aqueous solution tank, and simple piping, and the preparation device is mounted on a self-propelled mobile type, hand-held trolley mounted on a vehicle such as a truck. It becomes easy to make it portable, portable, etc. that are unitized as a whole.

According to invention of Claim 2 , the effective density | concentration or produced | generated amount of the chlorine dioxide to produce | generate can be controlled easily and reliably by adjusting the introduction speed | rate and density | concentration of a chlorite aqueous solution.

According to the invention of claim 3, since the chlorite aqueous solution is introduced into the reaction vessel so as to have a residence time of a certain level or more, particularly high chlorine dioxide generation in a wide concentration range of the chlorite aqueous solution. Efficiency is obtained.

  As described above, the method for preparing chlorine dioxide water according to the present invention is a reaction between a chlorite aqueous solution and a solid chlorinated chemical, and easily prepares a high concentration of neutral chlorine dioxide water. There is a feature that can be done.

Examples of the chlorite of the aqueous chlorite solution used in this preparation method include sodium chlorite (NaClO ₂ ) and potassium chlorite (KClO ₂ ).

On the other hand, maintaining the solid under normal temperature, the solid chlorinating agent to produce chlorine dioxide reacts by contact with chlorite aqueous solution, a salt thereof with a chlorinating isocyanuric acid, and chlorinated hydantoins In the present invention, trichloroisocyanuric acid is used to obtain particularly good results.

  Thus, for example, when the chlorite is a sodium salt and the solid chlorinated drug is trichloroisocyanuric acid, the chlorine dioxide production reaction is represented by the following formula (A).

6NaClO ₂ + C ₃ N ₃ O ₃ Cl ₃
→ 6ClO ₂ + C ₃ N ₃ O ₃ Na ₃ + 3NaCl (A)

In order to prepare chlorine dioxide water , as shown in FIG. 1, a molded product T in which a solid chlorinated chemical powder has been made into a tablet shape by press molding or the like is loaded into a reaction vessel 1. By introducing the chlorite aqueous solution S from the solution tank 2 by the pump P, a liquid passing method is adopted in which the generated chlorine dioxide water C is led out from the reaction vessel 1.

  That is, according to this liquid flow method, the molded product T of the solid chlorinated drug reacts in the form of gradually dissolving in the introduced chlorite aqueous solution S. The reaction solution 1 can be continuously introduced into the reaction vessel 1 and a reaction solution corresponding to the introduction amount can be continuously led out from the reaction vessel 1 so that the chlorine dioxide water C can be continuously prepared. It is also possible to produce a certain amount of chlorine dioxide water C by a badge type.

  And in such a liquid flow system, the chlorine dioxide water preparation apparatus can be constructed very simply by the reaction vessel 1 and the solution tank 2 and a simple piping configuration, and of course, the fixed type apparatus is a movable type. Depending on the amount of chlorine dioxide water to be prepared, there are various configurations such as a self-propelled mobile type mounted on a vehicle such as a truck, a portable type mounted on a handcart, etc., and a portable type unitized as a whole. Is possible.

Shape of the molded product T of the solid chlorinating agent, size, density is not particularly limited, it may be appropriately set in accordance with the discharge amount Ltd. required in the continuous preparation and dissolve properties. However, if the size of the molded product T is reduced, the specific surface area is increased accordingly and the solubility is increased. Although the pump P is used in FIG. 1, the solution tank 2 is disposed above the reaction vessel 1, and the aqueous chlorite solution S in the reaction vessel 1 is supplied into the reaction vessel 1 by gravity, Supply / stop and flow rate adjustment may be performed by a valve interposed in the supply pipe.

  The effective concentration or production amount of the generated chlorine dioxide water C is the amount of the molded product T in the reaction vessel 1, the concentration and flow rate of the chlorite aqueous solution S to be introduced, the residence time of the aqueous solution S in the reaction vessel 1 ( It can be adjusted according to the flow rate). Further, it has been found that the pH of the chlorine dioxide water C falls within a substantially neutral range as shown in Examples described later. When the solid chlorinated agent is trichloroisocyanuric acid, if the residence time of the chlorite aqueous solution S in the reaction vessel 1 is set to 0.5 hours or more, 80% or more in a wide concentration range of the aqueous solution S It has been found that high chlorine dioxide generation efficiency can be obtained.

  The concentration of the chlorite aqueous solution S to be introduced may be adjusted by dilution in an appropriate container such as the solution tank 2 or the introduction of the diluted stock solution and the diluted water into the reaction container 1 You may make it adjust with a ratio.

  The generated chlorine dioxide water C is accompanied by residual chlorine, and the lower the concentration of the chlorite aqueous solution S used, the higher the ratio of residual chlorine to chlorine dioxide. As a solution having a concentration of about 1% or more, a solution containing chlorine dioxide as a main component (a ratio of chlorine dioxide / free residual chlorine of 1 or more) can be obtained. Since baths and pools are basically sterilized by chlorine, it is advantageous that the chlorine dioxide water C used for disinfection of these facilities contains residual chlorine. Also, for example, in line washing in food factories, a high concentration sodium hypochlorite aqueous solution has been widely used in the past, but a large amount of rinsing water is required because the odor after washing due to the combination of chlorine and dirt is difficult to disappear On the other hand, even though this chlorine dioxide water C contains chlorine, chlorine dioxide decomposes the malodorous component and exhibits a deodorizing action. Savings.

Example 1
In the apparatus configuration shown in FIG. 1, a tablet T (diameter of about 30 mm, thickness of about 15 mm, weight) obtained by press-molding powder of trichloroisocyanuric acid (effective chlorine 90%) in a vertical cylindrical reaction vessel 1 (capacity: 670 ml). 30 g) 330 g (11 pieces) are charged, and a 2.5% sodium chlorite aqueous solution S (liquid temperature: 25 ° C.) is stored in the solution tank 2. The chlorine dioxide generation amount and pH of the chlorine dioxide water C introduced from the lower part and overflowed from the upper part of the reaction vessel 1 were measured. The results are shown in Table 1.

  The flow rate (introduced amount of sodium chlorite aqueous solution S) was changed in four stages as shown in Table 1, and the liquid residence time in the reaction vessel 1 was 335 ml from the capacity. The first and fourth stages are 2 hours, the second stage with a flow rate of 670 ml / hour is 1 hour, and the third stage with a flow rate of 170 ml / hour is about 4 hours. In addition, before starting the passage of the sodium chlorite aqueous solution S and after the end of the passage, tap water was passed through the reaction vessel 1 and the residual chlorine concentration generated from trichloroisocyanuric acid was measured. It was 2300 mg / L before the start of the liquid, and 1200 mg / L after the end of the entire liquid flow where the amount of trichloroisocyanuric acid was reduced to about 1/3.

  From the results in Table 1, in this preparation method, the liquid residence time in the reaction vessel 1 varies from 1 to 4 hours due to the change in the amount of sodium chlorite aqueous solution S introduced, and the trichloroisocyanuric acid in the reaction vessel 1 It can be seen that chlorine dioxide of around 12000 mg / L is stably generated even when the remaining amount is gradually reduced. In addition, since the chlorine dioxide water C to be produced is in a substantially neutral range of pH 5.8 to 7.2, even if it is added as much as necessary for the disinfection and sterilization to the target water system, The occurrence of various problems due to the acidification of the aqueous system can be avoided without changing the pH of the aqueous system, and there is no concern that the wetted parts made of metal will corrode with acid.

Reference Example When hydrochloric acid was added to an aqueous solution of sodium chlorite having a concentration of 2.5% to adjust to various pH values, and the change over time in the amount of chlorine dioxide generated was examined, the results shown in Table 2 were obtained.

  As shown in Table 2, the amount of chlorine dioxide tends to increase with time at any of pH 0.7, pH 1.5, and pH 2.7, and reaches a peak even after 5 hours at pH 1.5 and pH 2.7. Although not reached, it gradually decreases after 10 minutes at pH 0.1. From this result, in the conventional method of generating chlorine dioxide by the reaction of sodium chlorite and acid, the reaction efficiency is worse as the pH is higher even in the acidic region, and the amount of chlorine dioxide generated can be peaked in a short time. It can be seen that the pH needs to be set extremely low. However, if such strongly acidic chlorine dioxide water is used, various problems due to a significant pH drop occur depending on the aqueous system to be sterilized and sterilized, and corrosion due to an acid such as a metal wetted part is feared.

Example 2
In the apparatus configuration shown in FIG. 1, a vertical cylindrical reaction vessel 1 having a capacity of 1730 ml is used, and trichloroisocyanuric acid (effective chlorine 90%) powder is press-molded in the reaction vessel 1 with a diameter of about T 35 mm, thickness 18 mm, weight 30 g) 1200 g (40 pieces) are loaded, and the solution tank 2 contains a 2.5% sodium chlorite aqueous solution S (liquid temperature 20 ° C.). Is introduced into the reaction vessel 1 by the pump P at the respective flow rates shown in Tables 3 to 5 below, and chlorine dioxide (ClO ₂ ) in the chlorine dioxide water C derived from the reaction vessel 1 for each residence time indicated. The amount and pH of chlorite ion (ClO ₂ ⁻ ) were measured. The results are shown in Tables 3 to 5 together with the generation rate of chlorine dioxide (ClO ₂ ). The indicated height, residence time, and occurrence rate are as follows.

Height: Percentage of the height of the tablet T loading layer occupying the inner height of the reaction vessel 1, and gradually decreases as the tablet T is depleted due to the flow of liquid.
Residence time is the time required for the sodium chlorite aqueous solution S to pass through the tablet T loading layer in the reaction vessel 1, and as the height of the loading layer decreases due to depletion due to liquid passage. Shorter.
Occurrence rate: Percentage of chlorine dioxide produced with respect to chlorite ions derived from the introduced sodium chlorite aqueous solution S.

  As is apparent from the results of Tables 3 to 5, trichloroisocyanuric acid in the reaction vessel 1 was obtained at any flow rate of the 2.5% sodium chlorite aqueous solution S at 480 mL / hour, 960 mL / hour, and 1920 mL / hour. Until the height of the tablet T, that is, the remaining amount is about 30%, high-concentration chlorine dioxide is stably generated with high generation efficiency.

Example 3
In the same apparatus configuration as in Example 2 (reaction vessel 1 capacity 1730 ml), the same trichloroisocyanuric acid tablet T as in Example 2 was loaded into the reaction vessel 1 to a height of 80% and stored in the solution tank 2 A sodium chlorite aqueous solution S (liquid temperature 20 ° C.) having a concentration of 6 is introduced into the reaction vessel 1 by a pump P at the indicated flow rate, and in the chlorine dioxide water C derived from the reaction vessel 1 for each indicated flow rate. The amount and pH of chlorine dioxide (ClO ₂ ) and chlorite ions (ClO ₂ ⁻ ) were measured. The results are shown in Table 6 together with the generation rate and generation amount of chlorine dioxide (ClO ₂ ) and the chlorite ion residual rate.

As shown in Table 6, by setting the residence time to 0.5 hours or more, high chlorine dioxide generation of about 80% or more in the total concentration range of the sodium chlorite aqueous solution S of 0.11 to 5% the rate has been obtained, et al. Further, from the table, it can be seen that the residual chlorite ion is reduced to 1% or less when the residence time is 1 hour or more.

Example 4
In the same apparatus configuration as Example 2 (reaction vessel 1 capacity 1730 ml), the reaction vessel 1 was charged with 1200 g of the same trichloroisocyanuric acid tablet T as in Example 2, and chlorite having a concentration of 1.25% and 2.5%. Each of the aqueous sodium acid solutions S having the liquid temperature shown in Table 7 below was introduced into the reaction vessel 1 by a pump P at a flow rate of 960 mL / hour, and the carbon dioxide in the chlorine dioxide water C derived from the reaction vessel 1 was introduced. The amount of chlorine (ClO ₂ ) and chlorite ion (ClO ₂ ⁻ ) was measured. The results are shown in Table 7 together with the chlorine dioxide generation rate and the chlorite ion residual rate.

  As shown in the above table, even if the liquid temperature of the sodium chlorite aqueous solution S is 30 to 40 ° C., the chlorine dioxide generation rate is almost the same as that at the same liquid temperature of 20 ° C., but the chlorite ion residual rate is It is falling. Therefore, in facilities such as baths and pools that require attention to the chlorite ion concentration, there are many cases where the temperature environment is about 30 to 40 ° C. It is advantageous to decrease in the temperature range.

It is a schematic diagram which shows the adjustment apparatus of the chlorine dioxide water employ | adopted as the Example of this invention.

Explanation of symbols

1 Reaction vessel 2 Solution tank C Chlorine dioxide water P Pump S Sodium chlorite aqueous solution T Trichloroisocyanuric acid tablet

Claims (3)

  Chlorine dioxide water characterized in that an aqueous chlorite solution is introduced into a reaction vessel charged with a molded product of trichloroisocyanuric acid as a solid chlorinating agent and reacted, and the generated chlorine dioxide water is led out from the reaction vessel Preparation method.   2. The method for preparing chlorine dioxide water according to claim 1, wherein the effective concentration or amount of generated chlorine dioxide is controlled by adjusting the introduction rate and concentration of the chlorite aqueous solution. The method for preparing chlorine dioxide water according to claim 2 , wherein the chlorite aqueous solution is introduced into the reaction vessel with a residence time of 0.5 hours or more.

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