Efficient Extraction of Metal Ions Using a Recirculating Two‐Stage Flow Reactor

Abstract

AbstractWe report a simple flow reactor for the selective extraction of target metal ions from an aqueous solution, using passive mixers and liquid‐liquid separators. The extraction takes place in two stages. In the first stage, target metal ions are selectively transferred to an organic phase containing extractant molecules; and, in the second stage, an acid solution strips the metal ions from the organic phase and regenerates the (uncomplexed) extractant molecules, thereby allowing them to be recirculated through the reactor. Using aqueous mixtures of copper sulphate and nickel sulphate as test solutions, copper ion extraction rates of 98 % are achieved, using the copper‐selective phenolic oxime ligand 5‐(tert‐butyl)‐2‐hydroxybenzaldehyde oxime as a molecular extractant. The two‐stage, recirculating nature of the reactor minimises the use of both the extractant molecules and the supporting organic solvent, resulting in a greener, more economical process.