Evaluation of extractant-coated ferromagnetic microparticles for the recovery of hazardous metals from waste solution

A magnetically assisted chemical separation (MACS) process developed at Arg onne National Laboratory is a compact method for the extraction of transura nic (TRU) metals from, and volume reduction of, Liquid waste streams that e xist at many DOE sites. The MACS process utilized the selectivity afforded by solvent extractant/ion-exchange materials in conjunction with magnetic s eparation to provide a more efficient chemical separation. Recently, the pr inciple of the MACS process has been extended to the evaluation of acidic o rganophosphorus extractants for hazardous metal recovery from waste solutio ns. Moreover, process scale-up design issues were addressed in respect to p article filtration and recovery. Two acidic organophosphorus compounds have been investigated for hazardous metal recovery, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex(R) 272) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex(R) 301). These extractants coated onto magnetic microparticles demonstrated superior reco very of hazardous metals from solution as compared with data from solvent e xtraction experiments. The results illustrate the possibility for diverse a pplications of this technology far dilute waste streams. Preliminary proces s scale-up experiments with a high-gradient magnetic separator at Oak Ridge National Laboratory revealed the potential for very low microparticle loss rates.