Evaluation of mass transfer for metal removal via a liquid membrane-based process in a hollow-fiber membrane contactor

The extraction of metals using membrane-based solvent extraction processes offers many advan-tages over conventional technology. Hollow-fiber contactors have demonstrated great potential in large-scale application of this concept in extracting and recovering dissolved metals. In this process, the metal is extracted from an aqueous solution to an organic solvent through the walls of porous fibers. The organic solution can be composed of a diluent alone or a carrier dissolved in a diluent. The overall mass transfer of the extracted component is an important parameter that will provide guidelines in designing such a process. The value of the overall mass transfer coefficient can be calculated using correlation and analysis of the experimental data. In this work, a simplified equation is derived and is applied to the extraction of metals using liquid membranes in a hollow-fiber contac-tor. The analysis was conducted on the experimental data of (i) extraction of boron from groundwa-ter using sunflower-based liquid membrane and (ii) extraction of zinc using a kerosene-based liquid membrane (literature data). The values of the overall mass transfer coefficient determined from the simplified equation are smaller, compared to those calculated from the mass transfer correlations in the literature.