Synthesis Of High-Pure Chlorine Dioxide By Solid Heterogeneous Catalysis Method And Its Application In Removing Organic Pollutants In Tap Water

Chlorine dioxide?ClO₂?as a disinfectant is gradually replacing the liquid chlorine disinfectants because there is no carcinogen,teratogenesis and mutagen substances harming human health such as trihalomethanes?THMs?in the process of disinfection,and having good ability of sterilization.ClO₂ have been using as disinfection in drinking water in many developed countries,but it is rarely used in China because of the lower CIO2 production technology.In general,chlorine dioxide produced by a liquid phase syntesis method using sodium chlorate and sodium chlorite as the raw materials in the higher concentration acid media.It is high cost and no enough product purity.Therefore,it is the more important to find a novel method for producing high purity ClO₂ with the lower cost,which will be very helpful to eliminate the health problems in drinking water and greatly improve the living environmental quality of Chinese people.To solve this problem,we select potassium chlorate and oxalic acid as raw materials using the transition metals supported ZSM-5 as catalysts by solid-phase reaction method to prepare high-purity chlorine dioxide.It can avoid strong acid corrosion of the equipment and simplifying processing and shortening the reaction time for the preparation of ClO₂-No chlorine and other impurities in the product were detected,the optimized experimental conditions:the mole rario KClO3 to C2H4O2 is 1:1.2;reaction temperature of 75 ?;particle size of raw marerials of 200-250 mesh.The purity of chlorine dioxide prepared by this method can reach more than 99.9%.The purity of the product was estimated by Five-step iodometry,the national standard,and which is used to investigate the stability of chlorine dioxide,chlorate and chlorite in different temperature and pH conditions.The results show that chlorine dioxide can be stable and safest<25 ? in the airtight because chlorine dioxide?>1 g/L?will be volatile during storage.Chlorate and chlorite is very stable in water.Chlorine dioxide prepared by this method can also be used for oxidation treatment of benzene,phenol,quinone and aniline in water.The effects of the various factors,such as reaction time,mole ratio of ClO₂ to the organic molecules,pH and reaction temperature on the oxidation reaction were explored.The experimental results showed that ClO₂ can oxidize benzene to carbon dioxide,phenol to quinone,aniline to azobenzene,o-toluidine to o-methyl amino phenol,N-methyl aniline to N-methyl phenol and farther to quinine,but quinone cannot be oxidized by ClO₂.