Extraction of samarium using a serpentine Y-junction microreactor with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl

In the modern industrialized rare earths production, solvent extraction facilities possess many problems such as long extraction time, large occupation area, high processing cost and so on. The present work attempts to extract samarium (III) from hydrochloric acid solution in a rectangular cross-section Y-junction microchannel, using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl (EHEHPA or P507). The effects of flow rate, channel length and width on the extraction efficiency, slug length and mass behavior of a liquid-liquid extraction system are assessed. The slug length decreased with increase in the flow rate, increased in channel length and channel width. The maximum extraction efficiency of 75.1% could be achieved at the longer channel length (pH = 1.5, channel width = 300 μm, flow rate = 10 μL/min). The volumetric mass transfer coefficients (k_La) of the microfluidic extractor was compared with the conventional extractor and found to be several orders of magnitude higher, authenticating the beneficial effects such as: Higher specific interfacial area and shorter diffusion length.