Recovery of highly pure copper from waste cupronickel by electrolysis separation with low energy consumption: The role of deep eutectic solvent

Schematic diagram for the recycling of waste 90/10 cupronickel in 1 M CuCl+ChCl-EG DES. [Display omitted] •Separation of Cu from waste 90/10 cupronickel was feasible by electrorefining.•A mixture of [CuCl2]− and [CuCl3]2− species were formed in ChCl-EG DES.•Highly pure Cu (99.99 wt%) can be obtained at cell voltage of 0.4 V and 363 K.•Low energy consumption of 169.18 kW·h·t−1 was obtained.•Separation mechanism was proposed and the role of the DES electrolyte was revealed. The recovery of waste cupronickel not only can solve related environmental concerns but also facilitates the separation of valuable metals and reduces extra exploitation of natural ore resources. Here, high-efficiency and low-energy-consumption separation of copper (Cu) from waste 90/10 cupronickel (Ni ∼ 10 %) by electrolysis was clarified in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). Electrochemistry showed that Cu can be dissolved feasibly as monovalent Cu(I), forming species such as [CuCl2]− and [CuCl3]2−, while Ni was restrained and entered into anode slime at controlled potential. Compared with Ni(II), Cu(I) can be easily reduced to Cu0, and elevating temperature can accelerate ions transportation and reduction rates. Potentiostatic electrolysis at bath voltage of 0.4 V found that highly pure Cu (99.9918 wt%) was obtained and the current efficiency reached up to 99.71 % with low specific energy consumption (169.18 kW·h·t−1). A separation mechanism model of Cu from waste 90/10 cupronickel was proposed and the role of the DES was revealed, which possessed strong coordination ability and fast transport capacity for Cu(I), as well as significant potential difference between Cu and Ni. This strategy represents a promising and economical technique for recycling waste Cu-based alloy and extracting highly pure metals.