Extraction of Fe3+ from NaH2PO4 solution in a spiral microchannel device

To remove Fe3+ from NaH2PO4 solution for purification, the effect of the initial pH of NaH2PO4 solution, temperature, flow velocity, residence time and the ratio of organic phase to aqueous phase (O/A) are investigated using the spiral microchannel device with 1 mm inner diameter and adjustable length. It is found that there is a maximum percentage extraction at pH 3.5, the reactive extraction between Fe3+ and D2EHPA is endothermic and the mechanism can be proposed as Fe-(a)(3+)+ (HA)(J(O))reversible arrow (FeH(J-1)A(J))((0))(2+) + H-(a)(+). With the increase of flow velocity, the slug length decreases, and more intense dispersion of organic phase in aqueous phase can be obtained. The overall volumetric mass transfer coefficient increases with temperature and flow velocity, decreases with residence time. And the percentage extraction increases with temperature, flow velocity, residence time and phase ratio of O/A. The percentage extraction increases with the increase of extraction times and about 90% percentage extraction can be obtained after three stage extraction.