Effect of molecular weight of polyacrylic acid (PAA) on polyethersulfone membrane structure and performance

Research output: Contribution to conferenceAbstract


The novel method of modification of polyethersulfone (PES) ultrafiltration membranes is proposed. This method involves the use of aqueous solutions of polyacrylic acid (PAA) of different molecular weights (Mn=5.1×103 g·mol–1, Mn=490×103 g·mol–1) as a coagulant in non-solvent induced phase inversion process (NIPS). Addition of PAA (0.05–1.5 wt%) to the coagulation bath leads to marked changes in permeability and hydrophilicity of the surface of membrane selective layer. When the coagulation bath contains 0.5 wt% of PAA (Mn=5.1×103 g·mol–1) the rejection coefficient for polyvinulpyrrolidone (PVP К-30, Mn=40 kDa) decreases from 95% (for pristine PES membrane) to 80% (for membrane modified by PAA) and pure water flux (PWF) increases from 55 to 150 l·m-2·h-1. The presence of 0.1 wt% PAA (Mn=490×103 g·mol–1) in the coagulation bath results in an increase in PWF up to 220 l·m-2·h-1 and a decrease in rejection coefficient down to 35%. Water contact angles of the surface of the selective layer of modified membranes decreased down to 33o, for membranes, modified with PAA of higher molecular weights, and down to 43o for for membranes, modified by PAA with lower molecular weight (Mn=5.1×103 g·mol–1). The presence of PAA on the surface of PES membranes is confirmed by the FTIR spectroscopy. The membranes obtained by using PAA solution were pH-sensitive and pH-reversible, while the PWF of the initial membranes did not respond to the pH of feed solution. The SEM analysis of the structure of the membranes reveals marked difference in the morphology along cross section between the pristine and modified membranes. The suppression of macrovoids formation in the supporting layer of membrane with an increase in the concentration of PAA in the coagulation bath was noted. Fouling resistance behavior was studied using bovine serum albumin (BSA) solution in phosphate buffer. It was found that PAA addition to the coagulation bath enhances the fouling resistance of the modified membranes. The best fouling resistance with respect to BSA fouling is observed for the membranes with maximum hydrophilicity.

This work was supported by the Belarusian Republican Foundation for Fundamental Research, Grant No. X18MС-018 and STINT Grant no. IB 2017-7377.


External organisations
  • Institute of Physical Organic Chemistry of the National Academy of Sciences of Belarus
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Engineering and Technology
  • Chemical Engineering


  • Membrane, Membrane development
Original languageEnglish
Number of pages1
Publication statusPublished - 2019 Apr 8
Publication categoryResearch
EventEngineering with Membranes 2019: Membranes for a sustainable future - Hotel Skansen, Båstad, Sweden
Duration: 2018 Apr 82019 Apr 10


ConferenceEngineering with Membranes 2019
Abbreviated titleEWM 2019
Internet address