Modelling and Prediction of Permeate Flux in the Ultrafiltration Recovery of Sodium Lignosulfonate from Aqueous Solution

Modelling and data fitting for the prediction of permeate flux during ultrafiltration (UF) of a model feed solution of sodium lignosulfonate was carried out following resistance in series, gel polarization and Kedem Katchalsky equations. The experiments were conducted in a laboratory UF unit equipped with PES/HFUF asymmetric membrane under specific operating conditions by altering some parameters including solute concentration, transmembrane pressure (TMP), and cross flow velocity (CFV). The maximum experimental permeate flux was observed at TMP of 3.92 bar and CFV 0.527 ms-1 was 19.6 × 10-6 m3m-2s-1. The theoretical and experimental volumetric flux was plotted, and their extent of resemblance was compared and validated statistically. The study sheds light on the effective upcycling of sodium lignosulfonate from spent liquor via ultrafiltration.