Functionalization of polybenzimidizole membranes to impart negative charge and hydrophilicity

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

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Polybenzimidizole (PBI) is a promising material for membrane separations due to its high mechanical and thermal stabilities. Two drawbacks that can hinder the use of PBI membranes in water applications are low hydrophilicity and neutral charge at neutral pH values. To investigate methods to increase hydrophilicity and charge, PBI membranes were cast in the form of flat sheets using the phase-inversion technique and were functionalized with groups designed to modify the membrane surface. Specifically, three functional agents (taurine, para-phenylene diamine, and ethylene diamine) were chosen for surface modification based on their potential to impart charges and hydrophilicity on the PBI membrane. The surface of the PBI membrane was activated using 4-(chloromethyl) benzoic acid (CMBA). Characterization of the membrane was done using Fourier transform infrared spectroscopy in attenuated reflectance mode (FTIR-ATR), contact angle measurement, ζ potential, and environmental scanning electron microscopy (ESEM). Modification resulted in increased hydrophilicity and negative surface charge coverage. Pure water permeability was found to decrease by 33% after surface activation and by ∼70% after chemical modification as compared to that of the unmodified PBI membrane. Monovalent salt rejection was investigated using sodium chloride feed at concentrations from 3.4. mM to 100. mM and at pH values of 7 and 10. At both pH values salt rejection decreased exponentially with increasing concentration, and modified membranes provided higher rejections than unmodified membranes.

Original languageEnglish
Pages (from-to)195-203
Number of pages9
JournalJournal of Membrane Science
Volume363
Issue number1-2
DOIs
StatePublished - Nov 2010

Bibliographical note

Funding Information:
The authors would like to acknowledge grant NSF OISE 0832894 that supported the development of the collaboration on PBI FO research between The National University of Singapore and The University of Toledo. PBI Performance Products, Inc. (Charlotte, NC) is thanked for supplying PBI dope for the study. Professor Volodymyr Tarabara (Michigan State University) is also thanked.

Keywords

  • Charge
  • Functionalization
  • Hydrophilicity
  • Membrane separation
  • Polybenzimidizole

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science (all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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