Selective separation of Cu from large excess of Zn using a microfluidic platform

Abstract

A microfluidic platform, comprising a 800 μm diameter microbore tube connected to a 750 μm diameter opposed T-junction, to selectively extract copper from a large excess of zinc is reported. The effects of flow velocity (0.033 – 0.167 m/s) and ratio of the organic phase flow rate to the aqueous phase flow rate (O/A ratio, 1−2.5) on percent Cu extraction, Cu selectivity, stage efficiency, and overall volumetric mass transfer coefficient are studied. At O/A ratio of unity, maximum stage efficiency (98.90%) and maximum value of overall volumetric mass transfer (0.039 s−1) are obtained at flow velocity of 0.167 m/s. At these operating conditions, the values of % Cu extraction and Cu selectivity are 79.10% and 54.25%, respectively. Back extraction/stripping studies are also carried out to recover Cu in pure form in the strippant phase. Cu purity as high as 99% is obtained for O/A ratio of 1 and flow velocity of 0.167 m/s. High speed imaging studies are carried out to investigate the liquid-liquid two-phase flow pattern in the microchannels both during extraction as well as stripping.