Sorption of uranium(VI) and thorium(IV) by Jordanian bentonite

Purification of raw bentonite was done to remove quartz. this includes mixing the raw bentonite with water and then centrifuge it at 750 rpm; this process is repeated until white purified bentonite is obtained. xrd,xrf,ftir,and sem techniques will be used for the characterization of purified bentonite. the sorption behavior of purified jordanian bentonite towards uo 2 2 + and th 4+ metal ions in aqueous solutions was studied by batch experiment as a function of ph,contact time,temperature,and column techniques at 25.0 °c and ph = 3. the highest rate of metal ions uptake was observed after 18 h of shaking,and the uptake has increased with increasing ph and reached a maximum at ph = 3. bentonite has shown high metal ion uptake capacity toward uranium(vi) than thorium(iv). sorption data were evaluated according to the pseudo- second-order reaction kinetic. sorption isotherms were studied at temperatures 25.0 °c,35.0 °c,and 45.0 °c. the langmuir,freundlich,and dubinin-radushkevich (d-r) sorption models equations were applied and the proper constants were derived. it was found that the sorption process is enthalpy driven for uranium(vi) and thorium(iv). recovery of uranium(vi) and thorium(iv) ions after sorption was carried out by treatment of the loaded bentonite with different concentrations of hno 3 1.0 m,0.5 m,0.1 m,and 0.01 m. the best percent recovery for uranium(vi) and thorium(iv) was obtained when 1.0 m hno 3 was used. © 2013 fawwaz i. khalili et al.