Applied Basic Research On Bromine Extraction From Concentrated Seawater By D201 Strong Base Anion Exchange Resin

Bromine is an important basic chemical raw material. It is widely used,but short in national economy. The main industrial techniques for theextraction of bromine are high energy consumption, high cost, and highpollution, etc. Therefore, the development of new industrial techniques withlow energy consumption, low cost, and low pollution for the extraction ofbromine has attracted much attention recently. With the advantages asmentioned above, the method of ion exchange extraction of bromine hasshown the important application prospect. In this paper, applied basic researchon the extraction of bromine from desalinated seawater by D201 strong baseanion exchange resin was performed. This work should contribute to thesustainable development of bromine industry, the reducing of marineenvironmental pollution, and the comprehensive utilization of chemicalresources of desalinated seawater.The resin selective experiments showed D201 resin had a betteradsorptive capability than 201×7 resin or 201×4 resin. Using D201 resin, thestatic and dynamic adsorption experiments were conducted. The staticadsorption experiments implemented the adsorption thermodynamic andkinetic studies for the extraction of bromine from desalinated seawater. Theresults indicated that the maximum adsorptive capacity of wet D201 resin was0.105 g/mL, and the adsorption equilibrium data were well fitted with Henrytypeadsorption isotherm equation. Both the adsorption and desorptionprocess were endothermic, the increase of temperature favored two processes.The enthalpy changeΔH of the adsorption process was 7.746 kJ/mol, and thedesorption process wasΔH = 3.508 kJ/mol. The adsorption process wasparticle diffusion control, and the desorption process was controlled by liquid film diffusion.The dynamic adsorption experiments showed that the length of ionexchange band remained constant for a certain ion exchange system underconstant temperature and flow rate conditions, i.e., the height and diameter ofresin bed had no effect on the length of ion exchange band. When thetemperature was 25℃and the flow rate was 5 mL/min, the length of ionexchange band was 12.32 cm. The breakthrough leakage of resin bed couldbe controlled by the cascade operation of adsorption column, and threecolumns were determined by the length of ion exchange band. The stabilitytest showed that D201 resin had the superior performance of adsorption anddesorption, the long lifetime, and the high mechanical strength. Under theoptimum operation conditions, the repeated experiments were carried out andthe experiment data showed the good repeatability. This proved that thetechnological conditions for the extraction of bromine from desalinatedseawater by D201 resin was effective and stable.