CN1666615A

CN1666615A - Preparation method of high concentration hypochlorous acid disinfecting liquid

Info

Publication number: CN1666615A
Application number: CN 200510023766
Authority: CN
Inventors: 郑国生; 周家春
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2005-02-02
Filing date: 2005-02-02
Publication date: 2005-09-14

Abstract

The invention discloses a preparation method of high concentration hypochlorous acid disinfecting liquid which comprises the steps of, (1) one-step electrolyzing by employing cation membrane mode, using 0.1-10% chlorine-containing metal salt as the electrolytic solution, (2) stopping electrolysis when the pH of the anode side formation liquid falls down to 3-7.

Description

Preparation method of high-concentration hypochlorous acid disinfectant fluid

Technical Field

The invention relates to a method for producing a high-concentration chlorine-containing disinfectant by electrolysis, in particular to a method for producing a hypochlorous acid disinfectant by electrolysis.

Background

The chlorine-containing disinfectant is one of the most commonly used effective sterilization products in agriculture, food industry and environmental protection, and the effective component of the chlorine-containing disinfectant is hypochlorous acid or hypochlorite. According to the research of the United states Environmental Protection Agency (EPA), the bactericidal capacity of hypochlorous acid under the same conditions is tens to hundreds times that of hypochlorites. In order to exert the maximum sterilization efficiency of hypochlorite, people use the products in an acidic environment as much as possible, even the hypochlorite is adjusted to be acidic by using acid products such as hydrochloric acid before use, so the operation not only increases the cost, but also is inconvenient in practical use.

The generation of hypochlorous acid disinfectant by electrolysis using common salt or the like is one of the hot spots of international social studies in recent years. At present, a diaphragm type electrolysis device is mostly adopted for producing hypochlorous acid disinfectant by an electrolysis method, hypochlorous acid and hydrochloric acid are formed on an anode side, and a sodium hydroxide solution is formed on a cathode side. Theoretically, chlorine dissolves in water to generate hydrochloric acid and hypochlorous acid in equimolar amounts, and only 50% of chloride ions generate the required hypochlorous acid. It is worth pointing out that the chlorine generated on the anode side exists in the solution in three forms of chlorine gas, hypochlorous acid molecules or hypochlorite under different acidity, the chlorine mainly exists in the form of hypochlorous acid in the solution at the pH value of 4-6, the chlorine in the form of hypochlorous acid in the solution is reduced to below 80% at the pH value of 2, and only 30% at thepH value of 1, most of the generated chlorine exists in the form of gas, and when the concentration of the gas chlorine in the water exceeds the saturation concentration, a large amount of chlorine is precipitated from the solution. The common diaphragm type electrolysis method for producing the disinfectant can generate high-concentration hydrochloric acid while generating high-concentration chlorine concentration, so that the phenomenon of chlorine gas escape is usually generated, and the escape phenomenon is rapidly intensified along with the increase of acidity. In addition, the high acidity of the hypochlorous acid disinfectant also limits the application of the hypochlorous acid disinfectant in many occasions, and production equipment is easy to be corroded by acid.

When the disinfectant is actually used, the effective chlorine concentration is generally 10-100 ppm. In order to achieve effective disinfection concentration and prevent chlorine gas precipitation caused by over-high acidity, the electrolysis end point of the disinfectant is generally controlled to be 2-2.7 of pH value. When this degree of electrolysis is reached, the content of available chlorine produced is generally about 60ppm, at which time chlorine gas is already precipitated and a distinct chlorine odor is exhibited. In order to maintain the hypochlorous acid form of the available chlorine, the pH value of the electrolytic disinfectant is required to be 3 to 7. If only a common diaphragm type electrolytic device is used, when the pH value is 3-7, the concentration of the effective chlorine in the disinfectant is very low and can not reach the concentration required by actual disinfection; the pH value of the electrolytic disinfectant is far lower than the pH value of 3-7 when the available chlorine reaches the concentration required by disinfection. In a word, the disinfectant is directly electrolyzed and produced only by the conventional common diaphragm mode, and the effects of simultaneously keeping the effective chlorine concentration at 10-100 ppm and the acidity at 3-7 are difficult to achieve. In consideration of the problems of electrolysis efficiency, chlorine overflow reduction and the like, the concentration of the salt solution adopted by the current common electrolysis method is usually 0.1-0.2%.

Disclosure of Invention

The invention aims to solve the technical problems of low hypochlorous acid content and strong acidity of the disinfectant in the conventional electrolytic production method of the hypochlorous acid disinfectant, provides a method for producing the high-concentration hypochlorous acid disinfectant by electrolysis, and enhances the practicability of the electrolytic production method of the hypochlorous acid disinfectant.

The technical scheme of the invention is as follows: a preparation method of high-concentration hypochlorous acid disinfectant fluid comprises the following steps: a. adopting a cation diaphragm mode for one-step electrolysis, wherein the electrolysis stock solution is chlorine-containing metal salt with the concentration of 0.1-10%, and the electrolyte at the anode side is formed by mixing cathode side generated solution and the chlorine-containing metal salt; b. and stopping electrolysis when the pH value of the anode side generation liquid is reduced to 3-7.

The chlorine-containing metal salt is preferably NaCl or KCl.

The invention has the beneficial effects that: the electrolytic reaction of aqueous sodium chloride solution is generally as follows:

the electrode reaction in the dc electric field is:

anode:

cathode:

in the presence of an ion exchange membrane between the two electrodes, the hydroxide ions are progressively enriched on the cathode side due to the consumption of hydrogen ions, forming a NaOH solution.

The chlorine generated on the anode side reacts as follows: the generated HCl and HClO are subjected to neutralization reaction with NaOH in the anode side electrolyte to generate NaCl and NaClO, and the generated NaCl is continuously electrolyzed. And after NaOH is completely neutralized, continuously neutralizing NaClO by using HCl generated by electrolysis to generate HClO, and stopping electrolysis until the pH value is reduced to 3-7.

By adopting the steps, the invention utilizes the chlorine-containing metal salt with the concentration of 0.1-10% to electrolyze to generate the disinfectant fluid with hundreds to tens of thousands of ppm of effective chlorine, effectively overcomes the defects of low hypochlorous acid content, strong acidity of the disinfectant fluid and the like in the hypochlorous acid disinfectant fluid produced by the existing electrolytic method, and has obvious advantages in the aspects of use safety, convenience, cost saving, storage, transportation and the like. In addition, the anode side electrolysis stock solution uses part of the cathode side production solution, so that the effects of environmental protection and water saving are achieved.

Detailed Description

The present invention is described in further detail below with reference to examples: a preparation method of high-concentration hypochlorous acid disinfectant fluid comprises the following steps: a. adopting a cation diaphragm mode for one-step electrolysis, wherein the electrolysis stock solution is chlorine-containing metal salt with the concentration of 0.1-10%, and the electrolyte at the anode side is formed by mixing cathode side generated solution and the chlorine-containing metal salt; b. and stopping electrolysis when the pH value of the anode side generation liquid is reduced to 3-7. The chlorine-containing metal salt is preferably NaCl or KCl.

Example 1

In the first step, electrolyte with pH of 12.98 and NaCl concentration of 1% is prepared from cathode side production liquid, NaCl and water.

And secondly, placing the electrolyte on the anode side of a cation diaphragm electrolytic cell for electrolysis, wherein the pH of the electrolyte is continuously reduced along with the electrolysis, and when the pH reaches 5.5, the effective chlorine in the electrolysis generated solution is 3829ppm, and the pH of the cathode side is 13.38.

Example 2

In the first step, electrolyte with pH of 12.75 and NaCl concentration of 1% is prepared from cathode side production liquid, NaCl and water.

And secondly, placing the electrolyte on the anode side of a cation diaphragm electrolytic cell for electrolysis, wherein the pH of the electrolyte is continuously reduced along with the electrolysis, and when the pH reaches 6.2, the available chlorine in the electrolysis generated solution is 3049ppm, and the pH of the cathode side is 13.21.

Example 3

In the first step, electrolyte with pH of 12.83 and NaCl concentration of 1% is prepared from cathode side production liquid, NaCl and water.

And secondly, placing the electrolyte on the anode side of a cation diaphragm electrolytic cell for electrolysis, wherein the pH value of the electrolyte is continuously reduced along with the electrolysis, and when the pH value reaches 6.5, the available chlorine in the electrolysis generated solution is 3561ppm, and the pH value on the cathode side is 13.26.

The above description is only a basic description of the present invention, and any equivalent changes made according to the technical solution of the present invention should fall within the protection scope of the present invention.

Claims

1. A preparation method of high-concentration hypochlorous acid disinfectant fluid is characterized by comprising the following steps:

a. adopting a cation diaphragm mode for one-step electrolysis, wherein the electrolysis stock solution is chlorine-containing metal salt with the concentration of 0.1-10%, and the electrolyte at the anode side is formed by mixing cathode side generated solution and the chlorine-containing metal salt;

b. and stopping electrolysis when the pH value of the anode side generation liquid is reduced to 3-7.

2. The method for preparing high concentration hypochlorous acid disinfectant fluid according to claim 1, wherein the chlorine-containing metal salt is preferably NaCl or KCl.