1. chlorine dioxide generator
Properties and preparation of 1. 1 chlorine dioxide
Chlorine dioxide is an oxide of chlorine, which has a pungent smell similar to chlorine. The molecular formula is ClO2, the molecular weight is 67.457, the melting point is -59℃, and the boiling point is 1 1℃. It exists as a gas at room temperature and is a yellow-green gas. With the increase of concentration, the color becomes orange-red, and the gas chlorine dioxide is extremely unstable. Chlorine dioxide is easily soluble in water, and its solubility is 107.98mg/L/L at 20℃. It can be made into unstable liquid, and its liquid and gas are sensitive to temperature, pressure and light. When the air content is higher than 10%, the spark can be detonated [1]. Chlorine dioxide is an unstable compound, and it is also an unstable compound in air.
The methods of preparing chlorine dioxide by chlorine dioxide generator mainly include electrolytic method and chemical method. The widely used electrolysis method is diaphragm electrolysis, which uses salt as raw material to generate mixed solution containing chlorine dioxide, sodium hypochlorite, hydrogen peroxide and ozone under the action of electric field. The concentration of chlorine dioxide is generally only about 10-30%, and most of it is chlorine. Chemical methods mainly include two methods to generate chlorine dioxide from sodium chlorate and sodium chlorite. In the process of producing chlorine dioxide by sodium chlorate method, if chloride ion is used as reducing agent, the produced chlorine dioxide has the disadvantage of low purity, while the proportion of chlorine dioxide produced by sodium chlorite method is higher, generally above 90%.
1.2 Equipment and sterilization performance
The generators imported from abroad mainly include Tetralarent Company, Rio Lindo Company, Prominent Company of Germany, etc. Li et al. [3] reported the synergistic sterilization effect of chlorine dioxide cooperative sterilizer of Tetralarent Company. The generator uses electrolytic salt solution to generate chlorine dioxide, chlorine gas, ozone and hydrogen peroxide at the same time, which is dissolved in water and has synergistic sterilization effect, and its sterilization effect is better than any of the above disinfectants. The experimental results also show that the electrolytic voltage of the electrolyzer. Huan Pengcheng et al. [4] observed the disinfection effect of Vulcan Rio Linda T 140 chlorine dioxide generator in America. The concentration of chlorine dioxide generated by the generator can be adjusted to 2000-300mg /L, killing Escherichia coli and Staphylococcus aureus1mg/L for 3 minutes, and killing Bacillus subtilis var. The spore of Aspergillus Niger is 65438 0.25mg/L 5. Destroying HBsAg125mg/L for 2min, the minimum concentration of energy experiment is 400 mg/L, and 25% and 50% calf serum protective bacteria solution can affect the sterilization effect. At low concentration (10mg/L), the generator has slight corrosion to copper, carbon steel and aluminum, and basically has no corrosion to stainless steel.
The domestic chlorine dioxide generator has developed rapidly and the process is gradually mature [5]. At present, chlorine dioxide produced by electrolytic salt and positive and negative pressure chlorine dioxide generators produced by sodium chlorate and sodium chlorite methods have been used, and some products have obtained national patents. According to the working principle and operation characteristics of preparing chlorine dioxide mixed disinfectant by electrolysis, Ren [6] adopted single chip microcomputer technology and residual chlorine detector to realize the automatic control of the whole process of adding salt, discharging alkali and adjusting operation of chlorine dioxide disinfection equipment, which greatly improved the disinfection efficiency and the safe transportation of the equipment. Chlorine dioxide produced by chemical method has high content. The generator for producing chlorine dioxide by chemical method developed by Shi Laishun et al. [7] has the available chlorine content of 3246.6438 0 mg/L as determined by iodometry, and the solution contains chlorine dioxide and chlorine gas as detected by ultraviolet spectrophotometer and infrared spectrophotometer, in which chlorine dioxide accounts for 60%-70%. The germicidal efficacy of the aqueous solution showed that it contained 4.5-5.0 mg/L of active ingredients and acted on Staphylococcus aureus, Escherichia coli and Candida albicans in water for 65,438 0-2 minutes, and Bacillus subtilis was a variety. Niger contains 90 mg/L of active ingredients for 5 minutes. The antigenicity of HBsAg can be destroyed by the active ingredient containing 400 mg/L for 5 minutes. The performance of chlorine dioxide disinfectant in chlorine dioxide generator is unstable [8], and the degradation rate is 14.05% after storage for 3 days. However, if analytically pure sodium hydroxide is added to the disinfectant stock solution, the PH value is adjusted to 1 1.80, sealed and protected from light, and stored at room temperature (18 C-25.
Application of 1.3 in disinfection
At present, chlorine dioxide generator is mainly used for drinking water disinfection and sewage treatment. Chlorine-containing disinfectants used in traditional drinking water disinfection will produce a large number of halogenated hydrocarbons when treating raw water, including chloroform, chlorophenol, dichloroacetonitrile and other trihalomethanes.