Extraction of lanthanides by polysulfone microcapsules containing EHPNA. Ⅱ. Coaxial microfluidic method

Controllable preparation of small-size polysulfone microcapsules （MC） containing 2-ethylhexylphosphonic acid mono-2- ethylhexyl ester （EHPNA） by coaxial microfluidic method was focused on. N2 gas was used as continuous phase to disperse the polymer solution. The influence ofpolysulfone （PSF） content in the polymer solution and N2 gas flow rate on the structural properties and loading ratio of microcapsules was investigated. The mean diameter of prepared microcapsules was between 0.90 and 1.60 mm. Ultrasound method was adopted to import EHPNA into microcapsules. A very high extractant loading ratio of 6.21 g-EHPNA/g-PSF was achieved when the pore volume was 6.89 mL/g. The extraction performance was determined with lanthanides as the recovered components and with the prepared microcapsules as the separation agent. Close-packed microcapsules enjoyed a fast extraction kinetics. The maximum uptakes of La^3＋, Sm^3＋ and Er^3＋ were 3.02 ×10^4 mol/g, 8.05× 10^4 mol/g and 5.58× 10^4 tool/g, respectively. Microcapsules were reused seven times and showed very good stability. It is promising to apply the microcapsules into the extraction column and realize continuous operation.