Efficiency of hollow fiber modules for nondispersive chemical extraction

In this work the efficiency of hollow fiber solvent extraction for the system Me(ao)/bis(2-ethylhexyl) phosphate (DEPA) in isododecane (Me = Cd, Ni, Zn) has been studied from two points of view: wastewater treatment and hydrometallurgy. It was possible to achieve 2-4 orders of magnitude decrease of metal concentration in the aqueous phase by extraction in a single-pass flow mode. Furthermore the attainable phase ratios permit very high enrichment of metallic species (ca. 3 orders of magnitude) in the circle extraction-reextraction. Previously performed thorough studies on the kinetics and mechanism of the mass transfer in the investigated system (interfacial reaction, transport-limited process) allowed predictive modeling of hollow fiber reactive extraction. The necessary values of mass transfer coefficient were calculated using correlations existing in the literature, which were checked experimentally. The obtained results of extraction were compared with those for a pulsed sieve-plate column and an ideal mixer-settler cascade. It was shown that one module (54 cm length, 9000 fibers, or 25 cm and 31000 fibers) can replace an extraction column of 6 m length and two to four ideal stages. Presented results indicate the use of hollow fiber modules as high performance extraction devices.