Research On Adsorption Mechanism Of Bromine From Concentrated Seawater By D201 Resin And Analytical Methods Of Bromine

In this paper, we discussed the ion exchange thermodynamics and kinetics in order to study the adsorption mechanism of bromine from concentrated seawater by D201 resin, while the analytical methods of bromine were also compared for the further research on the mechanism.In the part of thermodynamics, we discussed the relationship of equilibrium concentration and equilibrium adsorption capacity, then calculated the thermodynamic functions (?H, ?G and ?S). The results indicated that the Langmuir adsorption equation was suited for this type of adsorption much better. The enthalpy change ?H of the bromine adsorption process was positive and between 20 and 40 kJ/mol, which indicated the process was the hydrogen adsorption. The adsorption process was spontaneous for the Gibbis free energy change ?G < 0. The entropy change ?S > 0, indicated that the adsorption was an entropic increasing process.In the part of kinetics, we measured the value of Qt in the process of adsorption at different temperature and initial concentration, calculated the activation energy Ea and the parameters of intra-partical and film diffusion and discussed the effect of temperature and initial concentration on adsorption. The results indicated that the very adsorption was fit for the first-order adsorption kinetics. This process was controlled by the two intra-partical and film diffusion, and the value of Ea was 13.1 kJ/mol. The rate and equilibrium adsorption capacity increased with the increasing of initial concentration. The increases of temperature were good for the adsorption, while had nothing to do with the rate.Finally, we did respectively discuss the operating conditions on ion chromatography, spectrophotometry and ion selective electrode. We also compared their precision. The results indicated that choosing 1.7mmol / L sodium carbonate and 1.8 mmol / L sodium bicarbonate to be eluent, 0.1mol / L sulfuric acid to be renewable liquid, 1.5mL/min to be their rates and 20μL to be injected for Ion chromatography were better. As to spectrophotometry, we chose 6mL concentrated sulfuric acid and 0.5mL hydrogen peroxide oxidation respectively. ion selective electrode, the volume ratio of buffer solution and sample solution was 2:1. The RSD% of three methods were 4.02, 2.34 and 3.23, which indicated that they were all applicable to the analysis of bromide concentration, and the best one was spectrophotometry.