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When a small amount of salt is added to tap water and electrolyzed through a diaphragm, the water generated at the anode has a quick-acting sterilization effect, and thus attracts attention.
Compared with general disinfectants, it has good performance in terms of safety and sterilization effect on organisms, but it is easily affected by ultraviolet rays and organic substances, and sometimes cannot achieve the expected effects.
1. The essence of electrolyzed acidic water
The method of activating water generally adopts electromagnetic properties, and the activation treatment process includes electrolysis method, high voltage treatment method, magnetic treatment method and other methods.
In order to promote the electrolysis of tap water, a small amount of salt is added, and the acidic water generated at the anode through the separator, especially the electrolytic acidic water as "sterilizing water", has been theoretically explained a lot.
This is only one of the so-called <functional water>, and the correct chemical term should be <anodic electrolytic salt water>. The functional water research and promotion consortium calls it "strongly acidic electrolyzed water". Here we call it <electrolyzed acidic water> for convenience.
As one of the indicators of the bactericidal performance of electrolyzed acidic water, the residual chlorine concentration is often mentioned. Practically all chlorides such as hypochlorite ion, hypochlorous acid, chlorine gas are included.
The development concept of electrolyzed acidic water is that the functional water with high bactericidal effect produced by electrolysis of tap water is hypochlorous acid solution.
The environment with the redox potential of 1100mv has greatly exceeded the limit of 900mv for the survival of microorganisms, so the microorganisms will die if they cannot survive. The idea under the assumption that microorganisms cannot survive in an environment of high redox potential (ORP). However, the research results show that although the redox potential is still an indicator value, it cannot fully represent everything 1).
2. The relationship between redox potential, pH value and hypochlorous acid concentration
Regarding redox potential, pH is an unavoidable question. Oxidized water is made from tap water as raw material, and there are various positive and negative ions. As a result, the relationship between the oxidation and reduction potential cannot be quantitatively expressed, but the relationship between the two can be qualitatively expressed as shown in the figure below.
To increase the redox potential, either increase the HOCI, or decrease the pH. The redox potential is correlated with pH and residual chlorine and does not change as an independent variable.
The compound form of chlorine in water is shown in the figure below.
At higher pH, dissociation accelerates to the right; at pH close to 2.7, approximately 90% will be in the form of HOCI (partially in chlorine). When electrolyzing brine, most of it will become HOCI at pH 5, and at pH 7.5, 1/2 will be HOCI, and 1/2 will exist in the form of OCI ions. When the pH of the solution tends to be acidic, chlorine gas will be generated, and when the pH of the solution tends to be alkaline, the proportion of hypochlorite ions will increase.
3. Sterilization mechanism
Bacteria are killed by chlorinating or oxidizing microbial proteins. Hypochlorous acid has a chlorination reaction to attach a chlorine component to a target and an oxidation reaction related to an oxygen component. In the latter, the hypochlorous acid solution tends to be acidic, and what kind of substance the hypochlorous acid will become after reacting with the organic matter, this changes according to different conditions.
The bactericidal power of hypochlorous acid is very strong. Compared with it, the bactericidal power of OCI ions is very weak, and CI ions have no bactericidal power. Chloride ions are not directly related to the bactericidal effect, and the chlorine that becomes an ion has neither oxidizing power nor bactericidal power. Therefore, the source of bactericidal power is not chloride ions, but hypochlorous acid in the pH range of acidic water. The hypochlorous acid in the electrolyzed acidic water has the effect of quickly killing bacterial cells. The principle is to destroy the enzymes of bacteria by releasing oxygen, to change the chemical properties of amino acids, and to destroy enzymes that are indispensable for oxidizing glucose, thereby causing adverse effects on the metabolic process, etc. There are many theories, it can be considered that is the result of the interaction of these mechanisms.
4. Acidity of acidic electrolyzed water
The pH of the acid water produced by electrolysis is about 2.7, which is due to the acidity of hydrochloric acid. Compared with concentrated hydrochloric acid (12N), this level of hydrochloric acid can be said to be very dilute. Because hydrochloric acid is a volatile acid, there is little residue and little adverse effect on human skin and mucous membranes. Therefore, the concentrated hydrochloric acid will not cause burns to the skin, and the irritation to the skin is very slight.
5. The influence of the presence of organic matter on the bactericidal effect
When using electrolyzed acidic water for daily clinical use, it should be noted that the presence of organic substances such as blood will drastically reduce the bactericidal effect.
pH cannot be used as an indicator of bactericidal effect. The redox potential is related to residual chlorine, so the redox potential can be used as an indicator to a certain extent, but fundamentally, the bactericidal effect is greatly affected by the amount of hypochlorous acid. When a trace amount of serum is added to the electrolytic acid water, the bactericidal effect will drop sharply.
6. Sustainability of the effect of electrolyzed acidic water
Hypochlorous acid is an unstable substance, and its reactive oxygen species have a short lifespan and will be decomposed by light, air, and other factors.
The effect retention time, the definition itself is the same, and it will be different according to the different types of manufacturing machines.
When storing strongly acidic electrolyzed water at room temperature, it should be kept in an airtight place away from light, and its period is 60 days. About the period
For the number of days, please refer to the following. Storage conditions are only in closed containers for a period of 15 days;
In the case of an open container, the period is 32 hours.
Whether it is hypochlorous acid or sodium hypochlorite, it will be reductively decomposed due to the influence of heat, ultraviolet rays, etc., resulting in a weakening of the redox potential. Moreover, it is easy to cause the weakening of the redox potential when it comes into contact with organic substances. While this substance has strong oxidizing ability, it has poor stability. Therefore, it is recommended to store in a cool place.
Using the principle that chlorine will make potassium iodide starch test paper turn blue and purple, it can be used as a simple method to detect the bactericidal power.
When the electrolyzed acid water is poured into the liquid storage tank and used, the residual chlorine concentration will be weakened due to the open container. Therefore, it needs to be replaced with a new one every time it is used.
7. Acute toxicity and chronic toxicity
It has been reported that electrolyzed acidic water has a destructive effect on various cultured cells and human lymphocytes. This destructive effect on cells is caused by chlorine, and its effect is small compared to other disinfectants.
In the future, electrolyzed acidic water is recognized as a medical product, and it needs to be tested for acute toxicity, sub-
Acute toxicity, primary skin irritation, continuous skin irritation, variability, reproductive toxicity, eye irritation, sensitization, etc. No studies have reported that this substance has any effect on living organisms
particularly toxic.
8. Regarding use in hospitals
The three major elements of traditional disinfectants are contact time, use temperature, and concentration. Compared with traditional disinfectants, there are no special requirements for the relationship between the three major elements and electrolyzed acidic water. Therefore, it is necessary to formulate a new concept for the electrolysis of acidic water.
A method to evaluate its disinfection effect based on in vitro results is being discussed. The effect of water clustering on the washing effect is expected. This electrolyzed acidic water can be understood as <washing water with bactericidal effect>.
8.1 Daily usage
1) After washing the non-metals once, it is used for the dipping method
2) Hygienic hand washing under running acidic water
3) Sterilize ingredients and utensils in the kitchen
When acid water is used for daily handwashing, in some cases with dry and rough hands, the number of bacteria increases after handwashing. Handwashing with acidic water cannot kill the bacteria attached to the fingers, and is not suitable for finger disinfection in the operating room.
8.2 For clinical treatment
At present, the safety to living organisms has not been confirmed, and it has not been recognized as a medical material; and there must be organic substances attached to the mucous membranes, so the effect of acidic water may be affected.
The following concentrated uses are mentioned in the Society's reports and literature. ① Wipe test on the patient, ② at the wound
setting, ③ oral care, ④ bedsore care, ⑤ atopic dermatitis, bacterial dermatitis ⑥ field of stomatology.
When used for bladder cleaning and bedsore treatment, the cleaning effect is more expected than the sterilization effect. In use, it is also necessary to pay attention to the removal of the leachate and necrotic substances before use.
Sodium hypochlorite on the market has a pH of 8.2, a HOCI of 15%, and an OCI of 85% at a concentration of 200 PPM that is actually used. There is a HOCI of 30PPM, which is the same as the available chlorine concentration of acidic electrolyzed water
(HOCI is 30PPM) basically the same. A big problem when used in large quantities for intra-abdominal cleaning. Therefore, under the circumstance that the safety of acid water has not been recognized at present, it is necessary to be cautious when it is used to clean the internal organs of the body cavity.
8.3 Environmental Pollution Caused by Abandonment
When electrolyzed acidic water comes into contact with the object to be sterilized, the oxidation-reduction potential and residual chlorine concentration will decrease.
However, the pH value is basically not affected and remains very low, so it cannot meet the drainage standard. Therefore, when a large amount is discarded, the pH of the microbial treatment tank in the sewage treatment facility will decrease, which will adversely affect the activated sludge, and there is a possibility of damaging the drainage pipe, so it is necessary to pay attention.
In this case, it is recommended to stir and neutralize the strongly alkaline reduced water produced at the same time when the electrolyzed acidic water is produced, and then discharge it.
8.4 Notes on use
The electrolysis of acidic water generates chlorine gas, so it is necessary to take measures against gas emission in manufacturing plants and storage containers. In particular, there is about 100PPM of chlorine in the upper space air of the storage container, and about 3PPM of chlorine near the bottom of the sink.
The chlorine gas produced by the electrolysis of acid water is heavier and toxic than air, so there will be great problems in the storage tank with a large volume and the closed room, so the ventilation problem of the production workshop and the working environment must be paid attention to.
Hypochlorous acid has a corrosive effect on metals and decolorization of fibers according to its oxidation effect. Corrosion-resistant materials include titanium, glass pottery, hard and soft plastic, polyvinylidene chloride, polyethylene resin, fluorine resin, etc.
9. Electrolysis of reactive oxygen species in acidic water
As other functions of electrolyzed acidic water, there are many reports on the treatment of atopic dermatitis and refractory wounds, but there are some phenomena that cannot be explained only by the bactericidal effect. This shows that in addition to the cleaning and sterilization effect on surface diseases, there may be other effects.
The effect of functional water is not only the bactericidal power, but also the removal of wound and necrotic tissue and the removal of bad odor.
The effect of other debridement, as well as the promotion of granulation formation and the reduction of leaching fluid, both promote the effect of skin blood flow. The active oxygen in acidic water as functional water includes, O -, ·O -, ·OH, 1O, HO, etc.
It can be produced from water, Hradical and OHradical, and 2Oradical can be produced from O2, and the latter can produce hydrogen peroxide (H2O2) after reaction with water. These Radicals have a very short lifespan, but OH radicals in the preservation solution of electrolyzed acidic water can exist stably for a long time.
On the other hand, this reactive oxygen species has adverse effects on organisms, such as destroying genes and killing cells with pharmacological effects. For the reason of appeal, when acid water is used in living organisms, care must be taken to use it on specific lesions within a short period of time.
10. Problems in the evaluation of the function of electrolyzed acidic water
Regarding the bactericidal effect, it can be understood as the effect of sodium hypochlorite through past research, but the hypochlorous acid in acid water has not been quantified, and the material balance of CI2 has not been fully discussed.
Therefore, it is necessary to prepare an aqueous solution of hypochlorous acid having the same concentration of hypochlorous acid as that of acidic water, and then to compare the sterilization effects. Also, a strong acid electrolyzed water (pH 2.7, ORP 1000mV) was produced with an unexpected electrolyte from NACI, and a comparative study of the bactericidal effect was conducted.
Regarding the therapeutic effect on atopic dermatitis, etc., it is necessary to compare the therapeutic effect with an aqueous solution of hypochlorous acid having the same concentration of hypochlorous acid as that of strongly acidic electrolyzed water.
In addition, the electrolytic solution other than NACI was used to produce strongly electrolyzed water with the same pH and potential, and the therapeutic effect was observed. When the effect of the hypochlorous acid aqueous solution does not change, it can be used as a material for confirming the therapeutic effect of active oxygen.
It is difficult to describe and prove the clinical effect of promoting wound healing, and evaluation is performed in consideration of the influence of the natural healing power possessed by the living body. The details of the active oxygen in the electrolyzed acidic water will require further studies in the future.
11. The debut of new electrolyzed water
The general performance of the models on the market is that the pH is 2.3-3.2 (average 2.7), the effective chlorine concentration is 7-50PPM, the redox potential is 1000-1200mV (average 1100), and the oxygen concentration is about 10PPM. The function of electrolyzing acidic water is determined based on the above four factors.
But recently, <weak acid electrolyzed water> with pH5.5, redox potential of 800-1000mV, and effective chlorine concentration of more than 50PPM has appeared. This is produced by electrolysis in the vicinity of pH 5.5, where the content of hypochlorous acid is the highest. The sterilization effect of this weakly acidic electrolyzed water is the same as that of diluting sodium hypochlorite to 200PPM, and it can effectively utilize residual chlorine.
<Neutral electrolyzed water> is a solution in the weakly acidic neutral range of pH 5.5-7. No matter which one is, from the perspective of redox potential, it is beyond the limit of microbial survival.
In the case of weak acid, in the inactivation test stored at room temperature, the residual chlorine concentration is very high, and the effect can be maintained for a long time and is stable. In particular, the chlorine concentration in the gas accumulated in the upper layer of the storage container is 100PPM in the case of strongly acidic electrolyzed water, compared to 1PPM in weakly acidic electrolyzed water, which shows that residual chlorine is not easily volatile in a weakly acidic environment .
In the deactivation test caused by organic matter, the conventional electrolytic acid water lost its bactericidal effect when the organic matter concentration was 0.1%, but the weakly acidic electrolyzed water did not lose its bactericidal effect when the organic matter concentration was 10 times the concentration of 1.0%. Indicates that weakly acidic electrolyzed water is not prone to deactivation caused by organic matter. In terms of the effect of combined use with general disinfectants (generally used pH5-8), weakly acidic electrolyzed water is more beneficial.
In terms of metal corrosiveness, the corrosiveness of weakly acidic electrolyzed water is also lower. In the case of weak acidity, the corrosion potential is about 470-600mV, and the potential of sodium hypochlorite (concentration 200PPM) is 800mV. The former has a lower corrosion potential. Therefore, the corrosion-resistant steel (SUS-316) is usually used at the temperature
Under, corrosion will not occur. In the test on metal corrosion, it was found that it gradually weakened in the following order: sodium hypochlorite, strong acid electrolyzed water, weak acid electrolyzed water.
Weak acid electrolyzed water has made up for the shortcomings of the past acid water, and has attracted attention as a new acid water.
Compared with the conventional disinfectants, it has the possibility of being widely used in the medical industry and various other fields after grasping the characteristics of drainage hazards, safety to living organisms, and bactericidal effects. However, the acute toxicity of cytotoxicity and chlorine gas is undeniable, so it is necessary to have a correct understanding of it.
It has been recognized in vitro for its strong sterilization effect, but it is thought that it will be difficult to use it as a substitute for the disinfectant used in daily life. Three factors, such as the amount of organic matter attached to the object to be disinfected, the type and the amount of bacteria, will affect the sterilization effect. In addition, on the issue of the indicator of bactericidal effect, pH has no indicator function at all, and redox potential can be used as an indicator to some extent. But the essence of bactericidal properties is hypochlorous acid.
