Surface functionalization of polybenzimidazole membranes to increase hydrophilicity and charge

Michael Flanagan, Richard Hausman, Brett Digman, Isabel C. Escobar, Maria Coleman, Tai Shung Chung

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

12 Scopus citations


Forward osmosis is the movement of water across a selectively permeable membrane. The driving force for water permeation through the membrane is the difference in osmotic pressure between the feed and draw solutions. Polybenzimidazole (PBI) is a material with excellent chemical resistance and high mechanical and thermal stability that is a promising material for forward osmosis separations. Drawbacks associated with the use of PBI as a membrane material include low hydrophilicity and surface charge neutrality. In this study, PBI membranes were cast using the phase-inversion technique in the form of flat sheets, and membrane surfaces were functionalized using different modifying agents with the goal of increasing hydrophilicity and surface charge. The negative charge on the membrane surface was expected to yield an increased rejection of ions and of negatively charged particles in the feed solution, while increased hydrophilicity decreases fouling propensity. The surfaces of the membranes were activated with 4-(chloromethyl) benzoic acid (CMBA). The modifying agents selected for membrane functionalization included: taurine, para-phenylene diamine, and ethylene diamine. These modifying agents were selected for their potential to impart a charge on the PBI membrane when in near neutral pH environments. Membranes were characterized using Fourier transform infrared spectroscopy in attenuated reflectance mode (FTIR-ATR), ζ potential, environmental scanning electron microscopy (ESEM), and contact angle measurements. Functionalization, surface charge, and increased hydrophilicity were all verified. Pure water permeability and salt rejection were tested for comparison between both virgin and modified membranes. Monovalent salt rejection was investigated using various sodium chloride feed concentrations, and a range of pH values.

Original languageEnglish
Title of host publicationModern Applications in Membrane Science and Technology
Number of pages19
StatePublished - 2011

Publication series

NameACS Symposium Series
ISSN (Print)0097-6156
ISSN (Electronic)1947-5918

ASJC Scopus subject areas

  • Chemistry (all)
  • Chemical Engineering (all)


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