| Bromine is one of the important industrial raw materials and has wide application in the national economy. 99% of bromine exists in sea water. With more and more demand of bromine in modern life, bromine extraction engineering from seawater shows importance increasingly. The current technologies of bromine extraction from seawater generally have many defects such as high energy consumption, complex process and high cost. Therefore, searching high efficiency and low cost method to extracted bromine ion directly from seawater has the vital significance. In this thesis, the adsorption properties of bromine ion in seawater are studied mainly using 201×7 strongly basic styrene type anion exchange resin.In this thesis, five kinds of determination methods of bromine ion in seawater are compared. Considering the accuracy of determination results, reproducibility and the operation difficulty degree as well as avoids using dangerous chemicals and so on, methyl orange spectrophotometry surpasses other four methods. The results of methyl orange spectrophotometry are that Recovery rate is 99.7%, correlation coefficient of standard curve is 0.9998.According to resins in literatures, 201×7,201×4 and D201 anion exchange resins are selected as adsorbent. Adsorption effects of bromine ion in standard solution and artificial seawater using these resins are researched from the capacity of static saturation adsorption, the time of static saturated adsorption as well as resistance to physical rupture ability. Results show that, the balance time of static adsorption is 40 minutes, static saturation adsorption capacities of bromine ion standard solution,artificially thick seawater with 128.26 mg·L-1 Br– and artificially seawater with 65.03 mg·L-1 Br– are 33.25 mg·g-1,25.94 mg·g-1and 29.42 mg·g-1 respectively.This thesis studies the adsorption properties of 201×7 resin as adsorbent to remove Br– from artificially thick seawater (128.26 mg·L-1 Br–) by static adsorption experiment and static desorption experiment. Results show that, increasing resin mass can improve the adsorption capacity, but when resin mass reaches the 1.0 g, the adsorption capacity is not obviously improved. So, resin mass selected at 1.0 g in this experiment. Between 288 K 328 K, elevated temperature is beneficial to this adsorption process, but the growing rate of adsorption rate is not obvious. So, experiments are performed at 298 K. Apparent rate constant of this adsorption process is 1.7×10-3 s-1 at 298 K, therefore, the adsorption rate was mainly governed by liquid film diffusion. And the adsorption process fit well to Freundlich model.Through infrared spectroscopy, chemical reaction of Resin's skeleton structure doesn't occur. It could be concluded that adsorption mechanism is electrostatic attraction between Br– and ( )—N +CH33. The static saturation adsorption capacity of bromine ion in natural seawater is 27.72 mg·g-1. And 1.5 mol·L-1 Sodium citrate solution is selected as desorption agent with desorption rate being 79.68%.By dynamic adsorption experiment and dynamic desorption experiment, results show that, low flow velocity is beneficial to this adsorption process. The capacity of dynamic adsorption is 13.42 mg·g-1at 2.3 ml·min-1, less than the capacity of static saturation adsorption, which shows effect of static adsorption is best than dynamic adsorption. Low desorption flow velocity is beneficial to this desorption process, but desorption capacity per minute is not improved with the velocity slower. Dynamic desorption capacity is 49.41 mg and dynamic desorption rate is 63.49% at 3.2 ml·min-1, which are less than static desorption. The adsorption capacity in natural seawater increases as time goes on, but after 72 hours, it decreases. The adsorption capacity is 38.57 mg·g-1at 72 h. |
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