Co, Mn and Cu usually coexist in the leachate of waste lithium ion batteries (LIBs). Extraction and separation of Co2+, Cu2+ and Mn2+ from sodium sulfate media by bis(2,4,4-trimethylpentyl) phosphinic acid, 2-ethylhexyl phosphinic acid mono-2-ethylhexyl ester and their mixtures in n-heptane have been investigated in detail. Synergistic enhancement coefficients, extraction reactions, infrared spectra, stripping properties and extraction selectivity were examined. A feasible separation process for recovery and separation of Mn, Cu and Co by the synergistic system was proposed and the mixed extractants could be used for reclaiming Mn, Cu and Co from the leachate of waste LIBs. (C) 2012 Elsevier B.V. All rights reserved.