Promotional effect of ammonium chloride functionalization on the performance of polyethersulfone/chitosan composite-based ultrafiltration membrane

Abstract

This study aims to determine the effect of ammonium chloride (NH4Cl) on the characteristics and performance of polyethersulfone (PES)/Chitosan (CS)-based ultrafiltration composite membranes. The PES membranes were synthesized using phase inversion technique in dimethylacetamide (DMAc) solvent. A mixture of chitosan solution (fixed concentration) and NH4Cl (concentration 100–400 ppm) with ratio 2:1 (v/v) were coated into the PES membrane. The synthesized membranes morphology and properties were characterized by FTIR, SEM, contact angle, mechanical properties, and porosity tests. The membrane performance parameters including water permeability, rejection, and antifouling properties were studied. Incorporation of NH4Cl modified the membrane morphology and improved membrane porosity (49.64–71.5 %). The decrease in the water contact angle (80.21° to 63.53°) has confirmed the improvement of membrane hydrophilicity. Moreover, improved mechanical properties (11–16 MPa) were observed due to NH4Cl addition. The incorporation of NH4Cl improved water flux and specific flux membranes in dead-end cell from 51.34 to 159.18 L/m2∙h and 22–26.53 L/m2∙h∙bar, respectively, and in the cross-flow cell from 82.38 to 182.53 L/m2∙h and from 16.47 to 36.51 L/m2∙h∙bar, respectively. The addition of NH4Cl into membrane remarkably improved the rejection of bovine serum albumine (75.90 %, to 96.79 %), methyl orange (47.18–89.29 %), and methylene blue (60.14–97.34 %) Composite membranes have good fouling resistance as indicated by an increase in the flux recovery ratio (53.58–70.67 %). It is inferred that the addition of NH4Cl improved the performance of PES/chitosan composite membranes in ultrafiltration.