Adsorption And Desorption Research On Bromine Extraction From Concentrated Seawater By D201Strong Base Anion Exchange Resin

This paper discussed the process of the adsorption and desorption onbromine extraction from concentrated seawater by D201strong base anionexchange resin and the theoretical model was also studied.The H, G, the apparent activation energy Ea, the apparent rateconstant k, the reaction order and rate determine steps in the staticadsorption and desorption process were studied. The results indicated thatthe Henry isothermal adsorption equation was suit for this type of the D201.The static adsorption was controlled by particle diffusion. The increasingtemperature was beneficial to the adsorption and desorption process.However, the increase of the bromine initial concentration had nothing todo with the solution dynamics. The static desorption was controlled byliquid film diffusion. The desorption rate increased rapidly with theincrease of initial concentration of the reducing agent, and the staticreduction rate could reach about99.3%.The fixed bed was used to the ion exchange column for studying theinfluencing factors of the adsorption and desorption process, such as theinitial bromine concentration, the initial operation flow rate, the reductantconcentration and flow rate, the eluent concentration and flow rate and so on. The results declared that the adsorption process of the resin bedutilization η1was about0.5525and the exchange high degree HLwas563.2mm. The dynamic adsorption rate increased with the increasing of theinitial seawater bromine concentration. Therefore, choosing200mg/L asthe initial concentration and15L/h as the liquid flow rate of the brominesolution were better. The experimental results showed that the optimumconditions for the reducing agent were1.5mol/L of the concentration and7.5L/h of the liquid flow rate. In addition, the HCl solution at theconcentration of2.0mol/L and the liquid flow rate of7.5L/h might be moresuitable.According to the assumptions and the laws, especially the material lawof conservation, the law of phase equilibrium, the liquid film diffusionequation and the particle diffusion equation, the ion exchange fixed bedadsorption-desorption model was built based on the boundary and initialconditions. Two groups of approximate solution were defined and had agood agreement with the experiment data. The results indicated that themodel and its approximate solution can be reflected the conditions of thefixed bed truly.