The Behavior And Mechanism For Synergism Adsorption Uranium(Ⅵ) On Modified Rice Stem And Modified Vermiculite

With the rapid development of the nuclear industry, the amount of radioactive wastewater produced in each process of nuclear is more and more. If we can’t dealt with radioactive wastewater properly, it will pose serious threat to ecological environment security and seriously endanger people’s health. It is getting more and more attention that how to well dealt with radioactive wastewater. For many years, people actively explored kinds of extensive, cheap, and environmentally friendly material to deal with radioactive wastewater.In this paper, modified rice stem and modified vermiculite were produced through different modification methods. The adsorption efficiency to uranium by modified rice stem and modified separately under different influencing factors as modified materials, p H, absorbent dose, adsorption time, initial concentration and temperature were studied. The thermodynamics and kinetics were analysed, and adsorption mechanism were discussed through FT-IR, SEM, EDS and XRD. Then modified rice stem in coordination with modified vermiculite adsorbing uranium were research to get the best synergy adsorption conditions. The conclusion is as follows:(1)The result showed that the rice stem can get well modified effect by 0.5mol/L Na OH. The best experimental conditions that PH is 4, adsorption time is 180 min, absorbent dose is about 5- 8 g/L, were got. The modified rice stem adsorb U(Ⅵ) well fit Langmuir isotherm model and pseudo-second-order equation. Surface adsorption is the predominant. The adsorption process is endothermic and spontaneous. Active groups of modified rice stem cellwalls can react with UO22+. Afte adsorption, surface morphology and part of the crystal structure of modified rice stem cellwalls changed.(2)Increasing the amount of adsorbent, time, and reducing the initial concentration of uranium can increased the removal rate of uranium.The adsorption equilibrium tends to be achieved in 120 min,and the best value of p H is about 6.5. The effects of the synergistic adsorption of uranium from aqueous solution using flocculant and modified vermiculite can be improved. The adsorption of uranium by organically modified vermiculite is a complex process,so Langmuir monolayer adsorption theory and Friendlies adsorption theory cannot fully explain the adsorption of adsorption process. The removal mechanism of uranium by using modifying vermiculite fits Langmuir adsorption law,and is in line with quasi—second order kinetic equation. It was confirmed by FT-IR that-OH and Si=O played an important role in the adsorption of uranium. SEM showed that the adsorption of uranium using modifying vermiculite cause the structure change.(3)The best adsorption condition of modified rice stem in coordination with modified vermiculite to deal with uranium is that PH value is about 5, adsorption time is about 16 min. The removal rate of uranium decreased and adsorption amount increased by increasing the concentration of uranium. With temperature increasing, the removal rate of uranium slightly raised, and the good adsorption effect can achieved in room temperature.