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Abstract:Competitive adsorption of Pb 2+ , Cd 2+ and Zn 2+ ions on sodium dodecyl sulfate (SDS) in binary mixtures were investigated compared with non-competitive adsorption in the unitary metal solution in micellar-enhanced ultrafiltration at a temperature of 25 • C. Mutual interference effects were investigated based on the removal rate, the Langmuir Competitive Model (LCM) and equilibrium adsorption capacity ratios, q e /q m , which indicated the presence of other metal ions. The results indicated that the removal rate and adsorption capacity of Pb 2+ were higher than that of the other metal ions in unitary and binary systems. The effects on SDS micelles for Cd-Pb and Zn-Pb combinations were found to be antagonistic. However, it was a favorable effect for the Cd-Zn combination, and the metal ions sorption followed the order: Pb 2+ > Cd 2+ > Zn 2+ . The behavior of non-competitive and competitive adsorption for Cd 2+ and Zn 2+ in a single system and in the presence of Pb 2+ were well described by LCM. Moreover, the LCM showed poor fitting to non-competitive and competitive adsorption of Pb 2+ in a single solution and in the presence of Cd 2+ or Zn 2+ . In conclusion, the removal of Pb 2+ in the presence of Zn 2+ or Cd 2+ showed greater efficacy than that of Cd 2+ or Zn 2+ in the presence of Pb 2+ .