Separation of In3+and Fe3+from sulfate solutions using D2EHPA in a laminar microreactor

A microfluidic solvent extraction method is put forward to solve the problems existing in the conventional solvent extraction of indium, such as large waste of extractant, fire hazards, etc. Experiments were performed in a series of microreactors to separate In3+ and Fe3+ from sulfate solutions using D2EHPA as the extractant. The effect of main parameters such as different contact times, microchannel sizes, interface to volume ratios and pH values on the indium extraction efficiency was investigated. The results show that the smaller the channel size, the more the beneficial diffusion and mass transfer. Specifically, in a microchannel, with a size of 100 μm × 50 μm × 120 mm, almost 100% extraction efficiency was reached with contact time about 0·5 s. The mean mass transfer rate can be as high as 0·291 g m− 2 s− 1, and the ratio of mean mass transfer rate of In3+ to that of Fe3+ can be as high as 29·76.