Improving Strontium Removal from Solution by Controlled Reflux Foam Separation

Controlled reflux was studied as a method for improving the efficiency of removing strontium from solution by foam separation. Tests were performed with solutions containing ⁸⁵S, 10⁻⁶ M Sr²⁺ carrier, and 90 to 100 ppm of the surfactant sodium dodecyl benzene sulfonate (NaDBS) in either distilled water or 0.005 M NaOH to 0.005 M Na₂CO₃ solution. Nearly constant feed rates were maintained at about 40 gal/ft² of column cross section per hour. With these conditions, the volume reduction factor was increased to 3700 (from a value of ≈ 30 for nonrefluxing systems) and the strontium decontamination factor was in excess of 10³. In general, the volume reduction was inversely proportional to the gas/liquid volume ratio but directly proportional to the percent of foam reflux; the strontium decontamination factor, however, did not change very much within the throughput range studied.