Modelling of ammonium fumarate recovery from model solutions by nanofiltration and reverse osmosis

Abstract

Total recycle (TR) and batch (B) recovery of ammonium fumarate from aqueous model solutions was studied in a pilot plant equipped with a spiral-wound thin-composite reverse osmosis (RO) and nanofiltration (NF) membranes at 40 °C and feed input absolute pressure ( P i) of about 60 and 20–40 bar, respectively. Modelling of both membrane processes under total recycle and batch testing was successfully carried out on the basis of the Spiegler–Kedem model, thus allowing the negative effect of solute concentration on solvent permeation flux ( J v) to be reconstructed with average percentage errors between experimental and calculated J v data of 8 and 13%, respectively. Such models allowed the most appropriate membrane process for a given solute concentration ratio ( ϕ) and recovery efficiency to be selected. If no reduction in the water intrinsic membrane hydraulic permeability ( L pWo) was accounted for, the performance of the RO module would overcome that of the NF module for any ϕ value in the range 1–4. In the case of a 30% reduction in L pWo, the performance of the NF module would become remunerative with respect to the RO module for ϕ values ranging from 1 to 2.45 on condition that the solute recovery efficiency was of the order of 90%.