18 Starting from a real Proton Exchange Membrane Fuel Cell (PEMFC) leachate, separation of the 19 strategic metals platinum(IV) and cobalt(II) was carried out using two distinct strategies applying ionic 20 liquids (ILs), either via solvent extraction (SX) or acidic aqueous biphasic system (AcABS). The 21 versatility of ILs and their ability to provide original solutions to common issues in the field of used 22 device recycling is illustrated, with both approaches critically compared. The highly hydrophobic 23 tetradecylpyridinium bis(trifluoromethanesulfonyl)imide ([C 14 pyr][NTf 2 ]) was synthesized and applied 24 to the separation of Pt/Co. This solvent was able to selectively extract over 98% of Pt(IV) from the 25 PEMFC leachate in one step while leaving Co(II) in the aqueous phase and exhibited the highest 26 reported partition of Pt(IV) in a [NTf 2 ]-based IL. In a second approach, the AcABS based on the fully 27 water-miscible tributyltetradecylphosphonium chloride ([P 44414 ]Cl), HCl and water, is compatible with 28 the concentrated nature of the leachate and extracts both platinum(IV) and cobalt(II) quantitatively. In 29 a second stage, a selective precipitation step enabled the recovery of platinum(IV) in the form of an 30 organometallic complex whilst leaving the co-extracted cobalt(II) in solution. This work represents the 31 2 first utilization of an AcABS for the recycling of a real waste technological object. These two different 32 types of ILs in both cases resulted in an efficient separation of Pt(IV) from Co(II), using two very 33 different pathways. The merit and transferability of each approach is critically compared, and 34 suggestions are made as to the suitable condition range for each technique. 35 36