| In this research,we used?-nano-Al2O3as sorbent.The adsorption properties and mechanisms of y-nano-Al2O3toward Os(?)were systematically studied in thesis.The research contents and the experimental results are as follows:1.The effect of different sorbents on the adsorption behavior for osmium in aqueous solution was studied,and ??nano-Al2O3 was the best sorbent.The Os(?)ions can be adsorbed and desorbed quantitatively at proper pH values.The sorption has been optimized with respect to the pH.Adsorption percentage of Os(?)is over 99%at the pH 3.5.This paper mainly studied the optimal conditions of Os(?)preconcentration.The optimal conditions of adsorption method are as follows:The sorption was carried out after constant temperature shaking for 6 min with the sorbent dose of 10 mg at room temperature.2 mL 0.1 mol/L HCI was used for the desorption of os(?)on-nano-Al2O3 and the recovery reached 99%.The enrichment factor value of?-nano-Al2O3 was 10.2.The adsorption of Os(?)ions onto ?-nano-Al2O3 properly correlated with the pseudo-second-order rate equation.The rate constant of second-order adsorption of Os(?)was 0.16 mg/mg.min at normal temperature,the activation energy was 16.98 kJ/mol.The dynamic data indicated that the particle diffusion was not the solely the rate controlling process for Os(?);namely,the overall rate process appears to be influenced by both the boundary layer resistance and the intraparticle diffusion.3.The Langmuir model and D-R could describe the adsorption of ?-nano-Al2O3 to Os(?)ions successfully over the whole range of concentration studied.The Langmuir model could describe the sorption of ?-nano-Al2O3 to Os(?)ions.The equilibrium constants R:lies between 0 and 1,indicating the sorption could be easily ongoing.The values of Gibbs free energy and standard enthalpy(?G0<0,?H0?0)may be interpreted as the spontaneous endothermic adsorption process.The adsorption energy of ?-nano-Al2O3was 3.06 kJ/mol,which indicated that the process belongs to physical adsorption.4.The adsorption of Os(?)onto ?-nano-Al2O3 in aqueous solution were also studied with fixed-bed column.The practical application shows that the properties of?-nano-Al2O3 are excellent.In the given experimental conditions,experimental results can be well fitted with Bohart-Adams equation,Thomas equation and Yoon-Nelson equation.The regeneration and subsequent use of ?-nano-Al2O3 shows that the adsorption process can be applied with column.It is clear that ?-nano-Al2O3 is a good adsorbents for Os(?)and have great potential for the removal of noble metal ions from aqueous systems.5.The detection limits(3a)of determining Os(?)ions with ?-nano-Al2O3 as sorbent was 0.037 ?g/mL(n=11),and the relative standard deviations was 0.325%(n=11).?-nano-Al2O3 displayed an excellent selectivity for rhodium adsorption from the common metals including Pb2+,Co2+,Cd2+,Ni2+,Cu2+,Zn2+,Fe3+together.The proposed method was applied to the determination of trace amount of osmium in synthetic samples,and the results are in good agreement with the certified values. |
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