Description of the variation of retention versus pH in nanofiltration of organic acids

Nanofiltration can be used to recover chemicals, like VFAs, produced by the fermentation of biomass. Solution pH is a key parameter for as well recovery using nanofiltration. Current work reports an experimental investigation carried out with single and mixed solutions that contain acetic, propionic, butyric acids, at various concentrations pHs. It shown retention VFAs increases solution following S-shaped curve related VFA dissociation. Retentions decrease concentration, influence being negligible low values more significant high values. A simple model proposed calculate retentions versus different given filtration flux, considering dissociation dissociated undissociated solutes. Calculated fit ones, on condition consider solutes pKa slightly higher than theoretical up 1.24 units, or variation membrane charge pH, corresponding effective between 5.44 5.80. Both assumptions are supported previous investigations.