BORON VOLATILIZATION AND ITS ISOTOPE FRACTIONATION DURING EVAPORATIONOF BORON SOLUTION

Evaporation experiments were undertaken to determine the volatility of parts-per-million concentrations of boron in water and dilute HCl in the presence and absence of equimolar mannitol and/or cesium. Multiple 10 mL aliquots prepared identically were evaporated to various extent s or just to dryness and heated 10-20 min after reaching dryness under filtered air at 60 degrees C. Boron was only retained quantitatively in water during evaporation and after reaching dryness in the presence of equimolar mannitol and cesium. Boron was retained quantitatively i n dilute HCl solution during evaporation, without mannitol or cesium. But it could be retained when the dilute HCl just reached dryness and thereafter only in the presence of equimolar mannitol. Isotopic measur ements of the evaporating solutions and residues indicate that the hea vier isotope, B-11, is preferentially lost from the near-neutral and a cidic solutions examined. The results are pertinent for procedures req uiring preconcentration of boron.