Study On The Purification Effect Of Polyaniline On Simulated Iodine Containing Wastewater

In recent years,radioactive elements have been widely used in industrial,military,energy,medical and agricultural fields.Among them,nuclear technology has the most application of radioactive elements,but it brings convenience to human society,but it also causes health and environmental risks,especially the gaseous,liquid and solid radioactive wastes generated in the application of nuclear technology,which brings potential harm to human beings and the environment.Among them,part of the radioactive iodine produced by nuclear facilities is released in the form of gaseous iodine,while the other part enters the waste water in the form of iodide ion,hypoiodate and iodine.The radioactive iodine in waste water has attracted extensive attention due to its characteristics such as wide range of water pollution,rapid diffusion and lasting harmness.At present,the main adsorption method and ion exchange method are used for the treatment of iodine in the atmosphere and water.The adsorption materials used in the adsorption method mainly include activated carbon,metal-organic framework,porous organic polymer,etc.However,the adsorption efficiency of activated carbon is low due to the competition between water and iodine at the adsorption site.The application of some metal-organic framework adsorbents in iodine capture and storage has been limited due to their poor water stability,high cost and high toxicity.Because of the strong affinity between Lewis basic nitrogen and Lewis acid iodine,different types of nitrogen-containing adsorbents have been widely used in the capture and storage of radioactive iodine in non-aqueous media.Polyaniline（PANI）is rich in nitrogen-containing functional groups,and the quinone structure of the nitrogen is Lewis base,while the iodine is Lewis acid.Therefore,it can be inferred that the interaction between the two will produce charge transfer to form the complex to achieve the purpose of removing the iodine.Based on this,this paper takes polyaniline as the research object.The effects of synthesis and reaction conditions of polyaniline on iodine removal properties were studied by static batch experiments.The structure of polyaniline was determined by FTIR characterization.The reaction path of I₂ removal from water by PANI and the existing form of I₂ on polyaniline were revealed by kinetic fitting,iodine direction experiment,XPS spectrum analysis and UV-Vis spectrum results.In order to improve the polyaniline under different concentrations of I₂ removal capacity,the preparation of phytic acid doped polyaniline（PANI/PA）,through the low temperature（400℃）,carbide KOH impregnation processing and high temperature activation（800℃）,the phytic acid doped polyaniline carbon-based adsorbent（PANI/PA-AC）,using static batch experiments,the different influence factors（such as synthetic conditions,reaction time,initial concentration of I₂,initial solution pH value,etc.）on the properties of material removal of I₂.The results showed that:The polyaniline prepared in this study can achieve good removal of I₂ in water within a wide pH range（3.0～7.0）where I₂ exists.In iodine solution of 100～500mg/L,the removal rate of polyaniline is about 80%.The adsorption process of I₂ on polyaniline is chemisorption.According to UV-Vis,XPS and iodine direction experiments,the reaction paths for the removal of I₂ by polyaniline were as follows:（1）the adsorption of I₂ accounted for 13.53%of the total removal amount,and 10.16%of I₂ may be doped on PANI in the form of I^-;（2）Part of I₂ exists in the form of I₃^-and I₂ after interaction with polyaniline;（3）The phytic acid-doped polyaniline carbonic adsorbents（PANI/PA-AC）prepared by two-step carbonization activation process have the characteristics of large specific surface area.Compared with PANI/PA-AC in I₂ solution of 200-500 mg/L,the I₂ removal rate of PANI/PA-AC reaches more than 89%,and the adsorption rate is faster.（4）PANI/PA-Ac is mainly chemisorption for I₂.