| Bromine is one of important chemical industrial material. Many kinds of bromine compounds have a special value in the national economy. Bromine is one of main chemical composition of concentrated seawater and its concentration is as nearly two times as that in seawater. Therefore, recovering bromine reasonably from concentrated seawater is not only may solve the problem of sustainable development resources, but also may reduce the marine environment pollution and promote the comprehensive utilization of chemistry resources of concentrated seawater. A novel method of recovering bromine absorbed on anion-exchange resin was studied in this paper, which costs few energy, has non-pollutions, dose not be influenced by season, and it is one kind of important application prospect technology of recovering bromine.In this paper, we selected 201×7 anion-exchange resin for recovering bromine. The adsorption rate of bromine was 98% at appropriately operating conditions and the adsorptive capacity was 2.489 mg/mL. Effects of time, temperature, pH and the amount of resin were investigated. The results indicated that the equilibrium time was 90 min; high temperature and low pH were benificial to the adsorption. The more resin we used, the better adsorptive rate we got. The thermodynamic behavior of bromine adsorption was researched. The results indicated that the experimental data were well fitted by Langmuir equation. The adsorption process was spontaneous for Gibbis free energy changeΔG < 0. The enthalpy changeΔH of the bromine adsorption process was positive, which indicated the process was endothermic. The entropy changeΔS > 0, indicated that the adsorption was an entropic increasing process. The dynamic behavior of bromine adsorption was researched. The results indicated that the dominant procedure was particle diffusion control and the apparent activation energy was 8.983 kJ/mol and reaction order was 0.5314. The stirring speed had little influence on the process and pH in the range 3.0～3.5 were advantaged to the reaction.The results of column dynamic adsorption show that the bromine could be efficiently adsorbed by 201×7 anion-exchange resin. Effects of flow rate, the height of column and concentration of concentrated seawater had been discussed in the researches. The results indicated that the suitable flow rate was 4.0 mL/min; the aspect ratio was 5.8 and the high concentration of concentrated seawater could be a positive factor for its competitive adsorption. The work behavior of ion exchange column was simulated and the simulated results fit experimental data well.The batch reducing experiment indicated that restoring time was 180 min and the reducing rate was 97.9%. The concentration of reducing agent was 1.0 mol/L and the reducing temperature was 25℃. Reduction rate constant was 0.012 min-1 and the apparent' activation energy was 7.183 kJ/mol. The dynamic elution experimental indicated that the concentration of eluent was 2.0 mol/L and the flow rate was 4.0 mL/min.
|
PDF Full Text Request