Preparation Of Functionalized Graphene Oxide And ItsPerformance Of Adsorption Of U(Ⅵ) In Aqueous Solution

Due to the large specific surface area, abundant oxygen-containing functional groups good thermal stability and mechanical properties, grephene oxide(GO)has wide potential application in adsorption of heavy metal ions in aqueous solution. Besides, the preparation method of GO is simple and the cost is low. Different modified GO adsorbents including the ethylenediamine tetraacetic acid disodium modified graphene oxide(EDTA-GO),amination graphene oxide(GO-NH2) and amidoxime graphene oxide(AO/GO) In my thesis have been prepared expected by change the shape and functional sites of GO, get environmental friendly adsorbents with high adsorption quantity, easy separation and good reusable. The SEM, EDS,XRD, FT–IR and TGA technology have been utilized to analyze the structure and properties of functionalized graphene oxide materials. The different condition such as the initial concentrations,initial pH values, contact time, temperature and ionic strength have been investigated to dicuss the t affect of adsorb U(VI) in aqueous solution In addition, we also discuss the adsorption kinetics, isotherms and thermodynamics to explore mechanism of adsorption of U(VI).Besides,the desorption and reuse properties of materials that prepared by GO also have been studied.The optimum pH of U(VI) adsorbed on EDTA-GO is 6.0 and the adsorption process is completed within 4.0 hours. Pseudo–second–order kinetics and Langmuir isotherms can well describe the process for EDTA-GO adsorb of U(VI) in aqueous solution, indicating chemical force is a power to control the adsorption and promoted the monolayer saturated adsorption amount to 212.77 mg·g-1. Thermodynamic study Show that the sorption process is endothermic and spontaneous. The influence of NaCl solution with different concentrations on the adsorption of U(VI) on EDTA-GO can be neglected. The elution rate can reach more than 80% using 1.0 mol·L-1HCl solution as the eluent. After four cycles ofadsorption-desorption, the adsorption capacity of EDTA-GO for U(VI) has a little change,demonstrates that EDTA-GO has excellent reusable.The optima pH of U(VI) adsorbed on GO-NH2 is 5.5 and the adsorption process reach equilibrium states within 4.0 hours. The adsorption kinetics result display that the adsorption followed pseudo–second–order kinetics,indicate that chemical force is a power to directe the adsorption. Adsorption isotherm study show that Langmuir isotherms can well describe the sorption process, monolayer saturated adsorption capacity is 22727mg·g-1. Thermodynamic function ΔH and ΔG indicate that the sorption process is endothermic and spontaneous. The influence of NaCl solution with different concentrations on the adsorption of U(VI) on GO-NH2 can be neglected. Adsorption-desorption experiment is performed using 1.0 mol·L-1HCl solution as eluent to desorption U(VI)adsorbed on GO-NH2, the elution rate can reach 90%. After three cycles of adsorption-desorption, the adsorption capacity of GO-NH2 for U(VI) has a little change,demonstrates that GO-NH2 has excellent reusable.The adsorption properties of AO/GO strong depended on solution pH. optima pH is5.0 for AO/GO adsorb of U(VI). The adsorption kinetics result display that adsorption process reach equilibrium states within 3.0 hours.,the adsorption followed pseudo–second–order kinetics, indicate that chemical force is a power to directe the adsorption. Adsorption isotherm study show that Langmuir isotherms can well describe the sorption process, monolayer saturated adsorption capacity is 285.71 mg·g-1.Thermodynamic study Show that the sorption process is endothermic and spontaneous.The impact of ionic strength on the adsorption of U(VI) on AO/GO can be neglected. 1.0mol·L-1HCl solution can well elute U(VI) adsorbed on GO-NH2, the elution rate is 84.3%.After three cycles of adsorption-desorption, the adsorption capacity of AO/GO for U(VI)has a little change, demonstrates that GO-NH2 has excellent reusable.