Microscopic characterization of FO/PRO membranes - A comparative study of CLSM, TEM and SEM

Yi Ning Wang, Jing Wei, Qianhong She, Federico Pacheco Oreamuno, Chuyang Y. Tang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Osmotically driven membrane processes (including forward osmosis (FO) and pressure retarded osmosis (PRO)) have received increasing attention in recent decades. The performance of an FO/PRO membrane is significantly limited by internal concentration polarization, which is a strong function of the membrane support layer pore structure. The objective of the current study was to develop microscopic characterization methods for quantitative/semiquantitative analysis of membrane pore structure (both pore diameter and porosity distribution across membrane thickness). The use of confocal laser scanning microscopy (CLSM) for noninvasive characterization of the internal pore structure of FO/PRO membranes is reported for the first time. By performing optical sectioning, information on pore diameter, porosity depth profile and pore connectivity can be obtained. The CLSM porosity results are further compared to those obtained using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and reasonably good agreement was observed. A comparison of these characterization methods reveals their complementary nature, and a combination of these techniques may allow a more comprehensive understanding of membrane structure. The current study also provided a comprehensive insight into the pore structure of commercially available FO/PRO membranes.

Original languageEnglish (US)
Pages (from-to)9995-10003
Number of pages9
JournalEnvironmental Science and Technology
Issue number18
StatePublished - Sep 18 2012

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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