posted on 2021-02-19, 13:03authored byMinerva Monroy-Barreto, Ana Nelly Bautista-Flores, Nadia M. Munguia Acevedo, Eduardo Rodriguez de San Miguel, Josefina de Gyves
Extraction
and recovery of palladium continues to be a technologically
and economically challenging task, particularly in the recycling process
of palladium from scrap automotive catalytic converters. In this work,
extraction and transport of palladium(II) from HCl media with and
without KSCN in the feed and/or in the stripping solutions by tris(2-ethylhexyl)
phosphate (TEHP) and tris(2-ethylhexyl) phosphate (TEHP)–triisobutylphosphine
sulfide (CYANEX 471X) mixture were studied in two- (liquid and membrane
extraction) or three-phase (polymer inclusion membrane, PIM) configurations.
Regarding PIMs, the efficiency factors (permeability, selectivity,
and stability) were determined. Numerical data analysis revealed that
the transport of palladium is achieved by a complex mechanism in which
the solvating effects of TEHP and TEHP–CYANEX 471X are coupled
to chloride ion co-transport and thiocyanic acid counter-transport.
Palladium recovery from a spent automotive catalytic converter was
accomplished (approximately 90%) with excellent separation from Pt(IV),
Fe(III), Al(III), and other components via the studied membrane systems.