CN1128096C

CN1128096C - Process for preparing stable ClO2 solution based on hydrochloric acid

Info

Publication number: CN1128096C
Application number: CN 99112023
Authority: CN
Inventors: 施来顺; 戴振国; 刘靖民; 王永芳; 谢朝仁; 赵吉云
Original assignee: Shandong Polytechnic University
Current assignee: Shandong Polytechnic University
Priority date: 1999-01-15
Filing date: 1999-01-15
Publication date: 2003-11-19
Anticipated expiration: 2019-01-15
Also published as: CN1261051A

Abstract

The present invention relates to a production method for a chlorine dioxide solution on the basis of the stability of hydrochloric acid. In the method of the present invention, sodium chlorate is used as an oxidizing agent and hydrochloric acid is used as a reducing agent for carried out reaction, and mixed gas of chlorine dioxide and chlorine is generated; then, the mixed gas is purified by a sodium chlorite solution, and pure chlorine dioxide gas is generated; the pure chlorine dioxide gas is stabilized and absorbed by sodium hydroxide (or sodium carbonate) and oxydol, and the stable chlorine dioxide solution is prepared. The method is carried out under the condition of negative pressure generated by a water jet injector, and the operation is continuous feeding. Compared with the similar technologies, the method has the advantages of simple operation, less device investment, high chlorine dioxide purity, etc.

Description

Stable chlorine dioxide solution production method based on hydrochloric acid

(I) technical field

The invention relates to a method for producing stable chlorine dioxide solution.

(II) background of the invention

Chlorine dioxide is a broad-spectrum disinfectant, but is not suitable for small and dispersive users because the chlorine dioxide is unstable in property, difficult to store and needs to be prepared and used on site. The stable chlorine dioxide solution can overcome the defect, so the development of the stable chlorine dioxide solution production method with simple process equipment and less investment is imperative. The generation method of chlorine dioxide is more, and the main raw material used is sodium chlorate. According to the difference of the reducing agent, the method can be divided into the following steps: the Mathieson method, which uses sulfur dioxide as a reducing agent and sulfuric acid as a medium, has the disadvantages of low yield and much waste acid. The R2 method uses sodium chlorate, sodium chloride and sulfuric acid as raw materials, wherein the sodium chloride is used as a reducing agent. The sodium chloride reacts with sulfuric acid to generate hydrogen chloride, and then sodium chlorate is further reduced to obtain chlorine dioxide. This process generates a large amount of wasteliquid containing sulfuric acid and sodium sulfate, and the recovery and disposal thereof are troublesome. The Solvey method uses sodium chlorate, sulfuric acid and methanol as raw materials, wherein the methanol is used as a reducing agent. The yield of the chlorine dioxide is 85-90%. The R8 method has been put into operation in 1985 in the United states, the used raw materials are the same as those of the Solvey method, the production capacity is improved due to the adoption of a unit reactor of reaction, namely evaporation and crystallization, and the conversion rate of the reaction is improved to more than 95 percent. The process has the advantages of simple operation, easy control, high production efficiency and the like. However, this process requires evaporation of water and consumes a large amount of steam. Chinese patent ZL93111202.8 and Chinese patent ZL97233737.7 disclose a novel technology of a negative-pressure aeration chlorine dioxide generator production process, and the technology takes sodium chlorate as an oxidant and hydrochloric acid as a reducing agent. Regarding the production method of stable chlorine dioxide, the chinese patent office discloses CN1075298A a method for producing high-concentration stable chlorine dioxide, which uses sodium chlorate, sulfuric acid and methanol as reaction raw materials, and sodium percarbonate solution as an absorption stabilizer. The disadvantages are that: the reaction is not stable and difficult to operate.

Disclosure of the invention

The invention aims to provide a method for producing high-purity stable chlorine dioxide solution with simple operation.

The present invention is achieved as follows. The production method comprises a chlorine dioxide generator, a purifier, an absorption tower, a water ejector and a residual liquid tank. Preparing 25-40% aqueous solution of sodium chlorate, and continuously adding sodium chlorate and hydrochloric acid into the negative pressure aeration chlorine dioxide generator through a charging titration valve according to the proportion of 1: 0.7-1.4 to generate mixed gas of chlorine dioxide and chlorine. The reaction is as follows:

and purifying the generated chlorine dioxide and chlorine gas mixed gas by using a 20-40% sodium chlorite aqueous solution to convert chlorine gas into chlorine dioxide, thereby generating pure chlorine dioxide gas. The reaction is as follows:

the purified pure chlorine dioxide gas is subjected to stable and repeated absorption by taking 1-3% of sodium hydroxide or 5-8% of sodium carbonate and 0.5-1.5% of hydrogen peroxide as circulating absorption liquid, and then the stable chlorine dioxide solution can be prepared. The sodium hydroxide or sodium carbonate and hydrogen peroxide can be added at one time or added continuously in batches. The residual liquid generated by the chlorine dioxide generator is led out from the generator and neutralized by sodium hydroxide solution, and disinfectant by-products can be produced for other uses. The negative pressure of the system is generated by a water ejector, so that the chlorine dioxide generator and the purifier operate under the negative pressure condition.

The invention is provided with the explosion-proof plugs at the top of the residual liquid tank and the purifier to ensure the safety of the production process. In order to ensure the continuous operation of the production process, the residual liquid tank, the purifier and the chlorine dioxide generator are connected in a two-stage parallel mode.

Compared with the prior art, the invention has the following advantages: continuous production, no residual liquid discharge, no environmental pollution, less equipment investment, small occupied area and high purity of chlorine dioxide.

(IV) detailed description of the preferred embodiments

The present invention is described in detail below:

the chlorine dioxide generator takes sodium chlorate as an oxidant and hydrochloric acid as a reducing agent to react, the sodium chlorate is prepared into 25-40% aqueous solution, and the aqueous solution and the hydrochloric acid are continuously added into the chlorine dioxide generator under the condition of negative pressure according to the proportion of 1: 0.7-1.4; the raffinate produced in the generator automatically flows into a raffinate tank, which may be neutralized with aqueous sodium hydroxide. And purifying the mixed gas of chlorine dioxide and chlorine generated in the generator by a 20-40% sodium chlorite aqueous solution after flowing through a purifier to generate pure chlorine dioxide gas. And (3) introducing the purified pure chlorine dioxide gas to an absorption device, and taking 1-3% of sodium hydroxide or 5-8% of sodium carbonate and 0.5-1.5% of hydrogen peroxide as circulating absorption liquid to perform stable and repeated absorption so as to prepare stable chlorine dioxide solution. The circulating absorption liquid repeatedly absorbs chlorine dioxide gas in the water ejector, the absorption tower and the circulating pump, and finally stable chlorine dioxide solution with the pH value of 8.2-9.2, the chlorine dioxide content of more than 2.0 percent and the chlorine dioxide purity of more than 98 percent can be prepared. If the system pressure is too high, the explosion-proof plug is started, and the safety of the production process is ensured. In the repeated absorption process, if the temperature of the circulating absorption liquid is too high, the circulating absorption liquid can be cooled by cooling water, and the temperature of the circulating absorption liquid is preferably controlled to be below 30 ℃.

Claims

1. The stable chlorine dioxide solution production method based on hydrochloric acid uses sodium chlorate as an oxidizing agent, hydrochloric acid as a reducing agent and sodium chlorite as a purifying agent, and the production method comprises a chlorine dioxide generator, a purifier, an absorption tower, a water injector and a residual liquid tank, and is characterized in that: (1) preparing 25-40% aqueous solution of sodium chlorate, and continuously adding sodium chlorate and hydrochloric acid into a chlorine dioxide generator under the negative pressure condition according to the proportion of 1: 0.7-1.4; (2) purifying the mixed gas of chlorine dioxide and chlorine generated in the generator by using a 20-40% sodium chlorite aqueous solution under the negative pressure condition to generate pure chlorine dioxide gas; (3) the pure chlorine dioxide gas is stably and repeatedly absorbed by using 1-3% of sodium hydroxide and 0.5-1.5% of hydrogen peroxide as circulating absorption liquid.

2. A stable chlorine dioxide production process as claimed in claim 1, characterized in that the sodium hydroxide used can also be replaced by 5-8% sodium carbonate.

3. A stable chlorine dioxide production process as claimed in claim 1, characterized in that explosion-proof plugs are provided at the top of the residue tank and the purifier.

4. A stable chlorine dioxide production process as claimed in claim 1, characterized in that the residue tank and the purifier are connected to the chlorine dioxide generator in a two-stage parallel connection.

5. A stable chlorine dioxide production process as claimed in claim 1, characterized in that the circulating absorption liquid is cooled with cooling water, the reaction temperature of the circulating absorption liquid being controlled below 30 ℃.