Mass transfer characteristics of vanadium species on the high-efficient solvent extraction of vanadium in microchannels/microreactors

[Display omitted] •V1 species perform lower interfacial disturbance degree.•V10 species possess greater interface migration capability.•The strengthening effect of microchannel is much stronger in mixed V4 and V10.•V4 species is the predominant vanadium species in the mass transfer process. The complex aqueous metal species distributions limit the purification technology. However, few researchers focus on the mass transfer about metal species. In this paper, the new microfluidic device Raydrop connecting with capillaries are used as microchannels/microreactors for the mass transfer characteristics investigation. The different vanadium solution conditions are applied for the two-phase interface and mass transfer coefficient study. It is proved that the smaller vanadium species, such as V1 species, perform lower interfacial disturbance degree, and their droplet size is larger and interfacial tension is more stable. Oppositely, V10 species possess greater interface migration capability on the liquid–liquid interface. The chemical reactions also behave positive effect on the interface transfer. Moreover, the different flow patterns, such as slug flow, droplet flow and annular flow, are decided by different reaction systems and flow rates. The strengthening effect of microchannel is much stronger in mixed V4 and V10 aqueous solution than that of single V4 and V10 aqueous solution no matter with and without reactions. While in the competitive extraction of vanadium and chromium, the HCrO4- and CrO42- species also reacted with H+, so the V4 species is the predominant vanadium species in the mass transfer process. This paper is promising for the understanding of mass transfer at molecular level.