Studies of halide ions mass transfer in nanofiltration — application to selective defluorination of brackish drinking water Original Research Article

The article deals with the possibilities of treating highly fluorinated brackish drinking waters using a polyamide nanofiltration (NF) membrane. Our approach is based on the phenomenological model of Spiegler, Kedem and Katchalsky under a dilute solution condition but neglecting the charges carried by the membrane used (denoted NF45 from Dow, USA). We have calculated the phenomenological parameters, (the membrane reflection coefficient) and Ps (the solute permeability), and observed that can be linked to the hydration energy of halide ions. Furthermore, appeared to be linked to a kind of electrolyte. Then values are highly dependent on the nature of the anion present in the salty solutions. If NF is generally dedicated to the elimination of divalent ions, the present work studied the potentialities of selectively separating the following single halide salts: NaF, NaCl, Nal, LiF and LiCl. For the first time we have checked that selective defluorination can be attained using aNF membrane showing a predominantly solution-diffusion mass transfer.