Halogen Recovery Of Photo-insensitive Halogenated Disinfection By-productions In Water By Vacuum Ultraviolet

The use of disinfection technology can effectively remove pathogenic microorganisms in drinking water and reduce the incidence of diseases such as cholera and typhoid.However,the use of disinfectants has created new problems.Disinfectants can interact with natural organic or inorganic substances present in water to generate new harmful substances-disinfection by-products(DBPs).Epidemiological studies have shown that some DBPs have harmful effect,which seriously harms human health;some DBPs even affect fertility and endanger the next generation,so it is important to detect the content of DBPs in water.Due to the many types of DBPs,it is difficult to analyze and detect them one by one,so some scholars have proposed a total indicator-total organic halogen(TOX)to indicate the content of DBPs.The traditional TOX analysis method has many disadvantages such as complicated operation and high cost.The research group proposed a new TOX analysis method(electrodialysis separation,UV photolysis conversion,and ion chromatography detection).This research focuses on the UV conversion part,and explores the relatively difficult method of vacuum ultraviolet(VUV)halogen recovery.The halogen recovery effect of DBPs was solved,and the VUV recovery halogen method was applied to real water samples(tap water and lake water).In addition,for the problem of excessive conversion of iodine ions during the photodegradation of organic iodine,this topic optimized the recovery method of iodine ions in organic iodine,and explored a one-step recovery method of iodide ions in the process of dehalogenating organic iodine by VUV.The main conclusions are as follows:The VUV recovery halogen method can effectively degrade chloroform,tribromomethane,monochloroacetic acid,and trichloroacetic acid,recover halogen ions.The recovery of chloride ions and bromine ions are 95%.The chloride and bromide ions are not converted during VUV and UV irradiation,which guarantees the effectiveness of the VUV recovery halogen method to re cover halogen ions by one step.The temperature increase during VUV photolysis of DBPs will not lead to dehalogenation of the four.The VUV recovery halogen method can also effectively convert the halogen element in organic halogens into negative monovalent halogen ions for one-step recovery in tap water.When the concentration of organic halogens is high,the standard recovery rate is low,and the recovery rate is still 90%.When the VUV dehalogenation technology is applied to lake water,its degradation a nd dehalogenation effect fluctuates greatly,and the recoveries of halogen ions are more than 80%.The effect of this technology is more stable in tap water and better than lake water.With the increase of the p H value of the iodine ion solution,the reten tion rate of iodine ions during VUV irradiation continued to increase,and the retention rate of iodide ions was close to 90% under the condition of p H>12.4.The experimental conditions for the one-step recovery of iodine ions were determined(p H>12.4).Under these conditions,the one-step recovery of iodide ions was achieved after photodegradation of organic iodine by VUV dehalogenation technology.While recovering iodine ions in one step,it has little effect on the recovery of ions in chlorinated and brominated DBPs.One step recovery method has certain applicability.