Solvent extraction performance of Sm (III) using a T-junction microreactor with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl (EHEHPA)

Solvent extraction of samarium (III) from hydrochloric acid solution using a T-junction microreactor, with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl (EHEHPA or P507) as the extractant has been investigated. Initially, the effect of aqueous pH, channel width, and channel length on the extraction of samarium was analyzed, and the maximum extraction efficiency (82.5%) was obtained under the optimal conditions: pH of 2.0, width of 1.6 mm and length of 1 m. Moreover, the slug flow was analyzed by using the photo imaging system, which shows that slug length tends to slightly increase with the increase of aqueous acidity and channel width. However, the channel length did not show significant effect on the slug length. Volumetric mass transfer coefficient (k(L)a) initially increases with the increasing of pH value but decreases after the pH surpasses 2.0. Increasing the flow rate shows a positive effect in promoting volumetric mass transfer coefficient while enhancing the channel width and length shows negative effect. The maximum mass transfer coefficient (0.05527 s(-1)) can be obtained with the residence time of 14.84 s, which is almost at the inlet of the channel. The study on the mass transfer behavior of samarium extraction in the T-junction can provide reference values for other researchers.