Emulsion liquid membrane for simultaneous extraction and separation of copper from nickel in ammoniacal solutions

Abstract

The separation of copper and nickel in ammonia solution is challenging in hydrometallurgy. In this work, an emulsion liquid membrane (ELM) was constructed using M5640 as an extractant, Span 80 as a non-ionic surfactant, and kerosene as a solvent for the selective separation of Cu(II) and Ni(II) in ammoniacal/ammonium chloride solutions. First, the stability of the emulsion liquid membrane was evaluated, and the parameters were optimized by response surface methodology (RSM). Subsequently, the critical factors affecting the separation of copper and nickel in ammonia solution, including extractant concentration, feed pH, internal phase concentration, and emulsification speed, were systematically studied. The results show that > 99.9 % of Cu(II) migrates from the feed phase to the internal phase, while only < 4.2 % of Ni (II) migrates. The separation coefficient of Cu(II) and Ni(II) reaches 114,000, indicating that the emulsion membrane can effectively separate Cu(II) and Ni(II) in an ammonia medium. Furthermore, the discussion on the separation mechanism shows that the difference in the reaction kinetics of Cu(NH3)42+ and Ni(NH3)62+ with M5640 is the main reason for the selective separation of Cu(II) and Ni(II) in ammonia solution.