Modeling of fluoride rejection from aqueous solution by nanofiltration process: single and binary solution

Abstract

This study was aimed at the investigation of fluoride (F-) rejection from single and binary solution by nanofiltration process (NF). The influence of various parameters such as the effect of solution pH, initial F- concentration, applied pressure, feed flux, and accompanying cations and anions in feed water has been reported. Besides, the solute rejection and Spiegler-Kedem models were applied for the better understanding of NF performance. In a single solution, the laboratory study demonstrated F- rejections with NF membranes to be higher than 85. Moreover, as applied pressure and feed flux increased F- rejection was observed to increase marginally whereas the opposite trend was observed when initial F- concentration in feed water was increased. Further, the depletion of F- rejection at 15 mg/L of F- was found to be associated with the presence of co-existing cation and anion in the feed water. The estimated average of pore radius and Delta x/A(k) of the NF membrane were 0.12 +/- 0.02 nm and 47.84 +/- 25.22 mm, respectively.