An innovatory technique based on
the process of selective permeation
across the membrane for the treatment of solutions containing polycarboxylic
acids strongly bonded with 241Am is formulated. The present
article illustrates the parametric results of the process of optimization
for the recovery or mitigation of 241Am activity from solutions
containing diethylenetriaminepentaacetic acid and lactic acid, applying
a methodology of the hollow-fiber renewable liquid membrane (HFRLM).
In the liquid-membrane (LM) phase, a cation exchanger-type organic
complexant, bis(2-ethylhexyl)hydrophosphoric acid (HDEHP), is incorporated
as an ion transporter. The optimized process conditions are as follows:
the LM phase containing 0.2 M (HDEHP)2/dodecane, pH of
feed solution 1.2 ± 0.05, receiving solution with the LM phase,
and 2 M HNO3 (1:4.5) in the form of emulsion. The flow
rates of recirculation are maintained as 30 and 20 LPH for solutions
of feed and receiving phases, respectively. With an overall mass transfer
coefficient, 2.43 × 10–3 cm min–1, 99.9% recovery of Am with its concentration upgradation > 10
times
is achieved. The separated product, Am(NO3)3, is amenable for precipitation as Am-oxalate, a precursor to yield
AmO2. After HFRLM treatment, the feed solution becomes
nonalpha waste for its rightful disposal. For process modeling, the
mass transfer coefficient of Am(III) is attributed to the multiple
mono- and biphasic chemical equilibria and a series of resistances
for ionic diffusion across the HFRLM system. This process has been
used successfully to alpha decontaminate, residual solution of the
simulated trivalent actinide–lanthanide separation with phosphorus-reagent
extraction from aqueous komplex process. In this, the alpha decontamination
factor obtained for a single-step operation of 8 h is 836. In the
two-step operation of HFRLM, the alpha activity in 5 L residual solution
is reduced from 2.34 × 108 to 1.01 × 103 BqL–1.