Continuous solvent sublation for the removal of uranyl ions from dilute aqueous solutions

A separation technique which is called ''Solvent Sublation'' was studied for removing uranyl ions from aqueous solutions at 298 K with di(2-ethylhexyl) phosphate (D2EHPA) in heptane or D2EHPA containing trioctylphosphine oxide (TOPO) in kerosene. The effects of operating factors on the percent removal of U(VI) were examined in counter-current flotation operation. Furthermore, the adsorption capacity of U(VI) per unit specific surface area was examined in terms of the gas holdup and bubble diameter. (1) The percent removal of U(VI) lowered with increasing electrolyte concentration, but increased with addition of sodium dodecyl benzenesulfonate (DBS) as a collector. However, the effect of DBS concentration on the percent removal of U(VI) lowered as the gas flow rate (u(G)) increases. The removals from aqueous solution of UO22+ dissolved in sea water were found to be about 80% without addition of DBS at u(G) = 0.265 cm s(-1) and u(W) = 0.106 cm s(-1). (2) The gas holdup (epsilon(G))) increased with increasing gas flow rate, liquid flow rate (u(W)) and ionic strength; little effect of DBS concentration on epsilon(G) was found. (3) The gas bubble diameter increased with increasing gas flow rate, but decreased as the ionic strength increases. The effects of liquid flow rate and DBS concentration on the percent removal of U(VI) were of little significance. (4) The adsorption capacity of U(VI) per unit specific surface area of gas bubble dispersion increased with an increase in the flow rate ratio of liquid to gas (u(W)/u(G)), and attained to a plateau as an equilibrium value, which decreased as an ionic strength increases.