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The pH value of slightly acidic electrolyzed water is between 5.0 and 6.5, which is slightly acidic. It has a significant bactericidal effect on most bacteria and viruses, and is harmless to the human body. In this paper, combined with the author's experimental research, the research status and application prospects of slightly acidic electrolyzed water in the fields of food processing and preservation, medical treatment and agriculture are reviewed.
The purpose of disinfectant is to eliminate or inhibit microbial contamination. Its principle of action is to destroy cell membranes, block bacterial uptake of food and waste excretion, and passivate its key enzymes. The ideal disinfectant should have the characteristics of broad bactericidal spectrum, stable performance, not easy to be affected by various physical and chemical factors, non-corrosive to disinfected items, no residue after disinfection, low price, convenient transportation, and mass production and supply. At present, the chemical disinfectants used in the market mainly include peroxyacetic acid, chlorine-containing disinfectants, chlorine dioxide, ozone, ethanol, and Xinjieermin, etc. These disinfectants cannot fully meet the requirements of ideal disinfectants. Recent studies have shown that the new type of disinfectant slightly acidic electrolyzed water has the characteristics of strong sterilization ability, wide sterilization range, no pollution, no residue, safety, reliability, non-toxic and harmless to human body, no skin irritation, convenient preparation and low price. . Acid electrolyzed water (AEW) is acid water with oxidizing ability obtained by continuous electrolysis of electrolyte-containing water through a specific electrolytic cell. It is also called acidified potential water or electrolytic oxidized water [2]. Due to the difference between the production equipment and the electrolyte, different types of acidic electrolyzed water can be generated, which are mainly divided into strongly acidic electrolyzed water and slightly acidic electrolyzed water. In 2002, Japan designated strongly acidic electrolyzed water and slightly acidic electrolyzed water as food additives (fungicides) under the name of hypochlorous acid water.
Production principle
At present, there have been various disclosures and applications of electrolyzing solutions containing chloride ions such as salt and hydrochloric acid to generate electrolyzed water containing HClO. However, it is known that HClO exhibits the
strongest bactericidal effect when it exists in the state of a monomer, but the bactericidal effect depends on the balance relationship of the pH value of the liquid, and under alkaline conditions, it becomes ClO- which has almost no bactericidal effect, When the pH value is below 4, it becomes chlorine gas and dissipates in a short time. Therefore, it is necessary to maintain the pH value at about 5.0 to 6.5 in order to allow the presence of HClO having a stable bactericidal power. The pH value of slightly acidic electrolyzed water (SLAEW) can be maintained between 5.0 and 6.5. It is electrolyzed by a DC voltage of about 2V in a one-chamber type, that is, a non-diaphragm electrolytic cell. The concentration is 2% to 6% A colorless, transparent, non-viscous liquid generated from dilute hydrochloric acid. Chlorine gas and H+ are generated at the anode of the electrolytic cell, wherein H+ is dissolved in water to make the pH value of water 5.0-6.5; chlorine gas reacts with water to generate hydrochloric acid and hypochlorous acid (HClO), so that the effective chlorine concentration in water reaches 10-30mg/L; cathode Only hydrogen is produced. The safety of SLAEW is worthy of recognition, and it has been applied to food sterilization in Japan. In addition, the pH value of SLAEW is 5.0-6.5, which is close to neutral, and does not require high materials for transportation and storage, so it is convenient for popularization and application.
Disinfection mechanism
The available chlorine in SLAEW is HClO, which is further decomposed to form new ecological oxygen [O]. The new ecological oxygen has a strong oxidizing property, which denatures the proteins of bacteria and viruses, thus causing the death of pathogenic microorganisms. In the process of sterilization and virus killing, hypochlorous acid can not only act on the cell wall and virus shell, but also because the molecule of hypochlorous acid is small and uncharged, it can penetrate into the body of bacteria (viruses) and bacteria (viruses) body proteins, nucleic acids, Oxidative reactions occur with enzymes, etc., resulting in the death of pathogenic microorganisms.
Features of SLAEW
With the frequent use of acidic electrolyzed water, it has been found that the current acidic electrolyzed water, especially strong acid electrolyzed water, has the following main problems: the existing strong acid electrolyzed water production equipment has low efficiency and high equipment manufacturing and production operation costs; Its strong acidity (pH value < 2.7) is corrosive to metal equipment, which limits its popularization and application in livestock and poultry breeding; the physical and chemical properties of strong acid electrolyzed water are unstable, and the reduction speed is fast, which is not conducive to storage [5] -7]. Many studies have shown that slightly acidic electrolyzed water has the following characteristics [8]: the existing SLAEW generation device can operate continuously, and the products in the generation process are not easily left in the environment with the air evaporation, and have no pollution to the environment; In addition to effective chlorine, it no longer produces oxygen or ozone and does not generate chlorine-based higher oxides such as HCIO2, HCIO3, HCIO4 and other products, and the concentration of by-products such as dissolved oxygen, ozone and oxychloride is low, which is green and environmentally friendly; Hydrochloric acid and tap water are used as raw materials, and the cost is relatively low; the slightly acidic electrolyzed water produced is a colorless, transparent, non-viscous liquid containing HClO. It is odorless or has a slight chlorine odor, and its pH value is close to 7, so it is not harmful to the human body and is almost non-corrosive to objects. In addition, after the action of slightly acidic electrolyzed water, oxidation-reduction reaction occurs to generate water. Since the raw material does not contain salt, even if it is dried after use, there will be no salt concentration and crystallization. SLAEW is easy to be oxidized and decomposed when exposed to light. After being placed in a closed light-shielding environment for 40 days, the effective chlorine concentration is 78% of the initial value, so it needs to be stored in a cool and airtight condition.
